~ GEPA

llllll

United Sta tes Center fo r Env i ronrventa l Env i ronmen ta l Pro tec t ion Research In fo rma t ion Agency C inc inna t i OH 45268

Tech no logy Tra n$ f er

Handbook

llllllll llllll

Improving POTW Performance Using the Composite Correct ion Program Approach

E PA -6 2 5 /6 - 84 -0 08

HANDBOOK

IMPROVING POTW PERFORMANCE U S I N G THE

COMPOSITE CORRECTION PROGRAM APPROACH

U. S. ENVIRONMENTAL PROTECTION AGENCY

C e n t e r f o r E n v i r o n m e n t a l R e s e a r c h I n f o ma t i on C i n c i n n a t i , O h i o 45268

O c t o b e r 1984

NOTICE

This document has been reviewed i n accordance w i t h t h e U.S. Environmental P r o t e c t i o n Agency's peer and a d m i n i s t r a t i v e review pol i c i e s and approved f o r p u b l i c a t i o n . Mention o f t rade names o r commercial products does n o t c o n s t i t u t e endorsement or recommendation f o r use.

ii

FOREWORD

The formation of the Environmental Protection Agency marked a new era of environmental awareness i n America. T h i s Agency's goals a re national i n scope and encompass broad responsibility i n the areas of a i r and water pollution, solid wastes, pesticides, hazardous wastes, and radiation. A v i t a l part of EPA's national pollution control e f fo r t i s the constant development and dissemination o f new technology.

I t i s clear tha t only the most effective design and operation of pollution contra1 f a c i l i t i e s will be adequate to ensure continued protection of th i s Nation's natural resources. I t i s essential t h a t we achieve the maximum performance possible of existing Pub1 ic ly Owned Treatment Works (POTWs) t o achieve maximum benefit from our expenditures.

The purpose of this Handbook i s t o provide POTW owners/administrators and the engineering community w i t h a new source of information t o be used i n improving the . performance of POTWs th rough application of the Composite Correction Program ( C C P ) approach. I t i s the intent of the manual to supplement the existing body o f knowledge i n this area.

This Handbook is one of several pub1 ications a v a i l ab1 e from Techno1 ogy Transfer to describe techno1 ogical advances and present new information.

i i i

I

ACKNOWLEDGMENTS

Many i n d i v i d u a l s c o n t r i b u t e d t o t h e preparat ion and rev iew o f t h i s Handbook. Contract admin i s t ra t i on was provided by the U.S. Environmental P r o t e c t i o n Agency (EPA) , Center f o r Environmental Research Informat ion, C inc inna t i , Ohio.

CONTRACTOR-AUTHORS

Major Aut ho r s :

CONTRACT SUPERVISORS

P r o j ec t O f f i c e r :

Reviewers:

TECHNICAL PEER REVIEWERS

Bob A. Hegg, James R. Schultz, and Kerwin L. Rakness, Process Appl i c a t i o n s Inc., F o r t Co l l ins, C O

Denis J. Luss ier , EPA-CERI, C inc inna t i , OH

Jon H. Bender, EPA-MERL, C inc inna t i , OH Char1 es E. Gross , EPA-OWPO, Washington, DC Torsten Rothman, Dynamac Corp. , Rockvi l l e , MD

Thomas M. Rachford, Gannett F1 eming Environmental Engineers,

Stephen Poloncsik, EPA Region 5, Chicago, I L Walter G. G i l b e r t , EPA-OWPO, Washington, DC

Inc. , Harr isburg , PA

i v

CO NT ENT S

ChaDter

3

4

5

FOREWORD ACKNOWLEDGMENTS LIST OF FIGURES LIST OF TABLES

I NTRO D UC T I 0 N

1.1 Purpose and Scope 1.2 Background 1.3 Overview 1.4 References

APPROACH TO CONDUCTING COMPREHENSIVE PERFORMANCE EVALUATIONS

iii i v

v i i v i i i

2.1 Ob jec t ive 5 2.2 Me thodol ogy 5 2.3 Personnel C a p a b i l i t i e s f o r Conducting CPEs 12 2.4 Es t ima t ing CPE Costs 13 2.5 References 1 4

HOW TO CONDUCT COMPREHENSIVE PERFORMANCE EVALUATIONS

3.1 In t roduc t i on 3.2 I n i t i a l A c t i v i t i e s 3.3 Data C o l l e c t i o n 3.4 Eva lua t i on o f Major U n i t Processes 3.5 Eval u a t i o n of Performance-Limi t i n g Factors 3.6 Performance Eval u a t i o n 3.7 Presentat ion t o POTW A d n i n i s t r a t o r s and S t a f f 3.8 CPE Report 3.9 Example CPE 3.10 CPE Resu l ts 3.11 CPE Worksheets 3.12 References

APPROACH TO CONDUCTING COMPOSITE CORRECTION PROGRAMS

4.1 Ob jec t i ve 4.2 Methodol ogy 4.3 Persennel Capabil i t i e s ' f o r Conducting CCPs 4.4 Es t imat ing CCP Costs 4.5 References

HOW TO CONDUCT COMPOSITE CORRECTION PROGRAMS

5.1 I n t r o d u c t i o n 5.2 CCP A c t i v i t i e s

16 16 20 25 45 56 58 59 61 69 69 69

71 72 74 76 77

78 78

V

CONTENTS (cont inued)

Page Chapter

5

APPENDIX

A

B .

C

D

E

F

G

H

I

HOW TO CONDUCT COMPOSITE CORRECTION PROGRAMS (Cont. )

5.3 I n i t i a l S i t e V i s i t 79 5.4 Improving Design Performance-Limi t i n g Factors 83 5.5 Improving Maintenance Performance-Limi t i n g Factors 85 5.6 Improving Admin i s t ra t i ve Performance-Limi t i n g Factors 86 5.7 Improving Operational Performance-Limi t i n g Factors 86 5.8 Example CCP 103 5.9 CCP Resul ts 106 5.10 References 108

CPE CLASSIFICATION SYSTEM, CHECKLIST AND G U I DELI NES FOR PERFORMANCE-L I M I T I NG FACTORS 110

CPE SUMMARY SHEET FOR RANKING PERFORMANCE-L IMITING FACTORS 127

EXAMPLE CPE REPORT 130

DATA COLLECTION FORMS USED I N CONDUCTING CPEs 137

GUIDELINES FOR FIELD ESTIMATING EQUIPMENT POWER USAGE 182

PROCEDURE FOR CONVERTING STANDARD OXYGENATION RATES TO ACTUAL OXYGENATION RATES 185

EXAMPLE FORMS FOR ESTABLISHING A PREVENTIVE MAINTENANCE PROGRAM FOR SMALL POTWs 190

DESIGN RELATED PERFORMANCE-LIMITING FACTORS IDENTIFIED I N ACTUAL CPEs 196

EXAMPLE PROCESS MONITORING SLNMARY FOR AN ACTIVATED SLUDGE POTW 208

EXAMPLE PROCESS MONITORING SUMMARY FOR AN RBC POTW 214

PARAMETERS USED TO MONITOR THE ABF TREATMENT PROCESS 21 9

SUSPENDED GROWTH MAJOR UNIT PROCESS EVALUATION WORKSHEET 225

TRICKLING FILTER MAJOR UNIT PROCESS EVALUATION WORKSHEET 2 35

RBC MAJOR UNIT PROCESS EVALUATION WORKSHEET 242

0 ABF MAJOR UNIT PROCESS EVALUATION WORKSHEET

v i

250

LIST OF FIGURES

Number Page -

2 -1

3-1

3 -2

3-3

4-1

5-1 5-2

5-3 5-4 . 5 -5 5 -6 5-7

5 -8

F-1

CPE/CCP Schematic of Activities

E f f e c t of Aeration Basin DO Concentrations on Sludge S e t t l ing Characteristics

Typical Return Sludge Flow Rates w i t h Various C l a r i f i e r Surface Overflow Rates

Flow Diagram of POTW i n Example CPE

Re1 a t i o n s h i p s of Performance-Limi t i n g Fac tors t o Achieving a Performance Goal

Typical Schedul i ng of Onsi te and Of f s i te Invol vement Sample Process Control and Performance Moni t o r i n g

Representat ions of Act ivated S1 udge Floc Act ivated Sludge Mass Control Using MCRT Act ivated Sludge Mass Control Using Total Sludge Mass Si mpl i f i ed Acti vated S1 udge Proces Process Control Tes t ing a t a 950 I3 /d Oiagram Contact

Graphical Representat ion of Improved Performance from

Form f o r a Small POTW

S t a b i l i z a t i o n POTW

a Successful CCP

Atmospheric Pressure a t Various A1 t i tudes

6

52

54 62

73

80

82 80 91 92 93

99

107

189

v i i

LIST OF TABLES

Number

2-1

2 -2

3-1 3-2

3 -3 3 -4

3 -5

3 -6

3 -7

3-8 a

3-9

3-10

3-11 3-1 2

3-13 3-14 3-15

3-16

3-1 7

3-18 3-19 3-20 3-21

3-22

4-1

5 -1 5-2 ~

C l a s s i f i c a t i o n System f o r P r i o r i t i z i n g Performance-Limi t i n q Factors Typical Costs f o r Conducting CPEs

Pre l im inary P lan t In fo rmat ion t o C o l l e c t by Telephone Parameters f o r Scor ing Capabil i ty o f Ae ra t i on Basins

i n Suspended Growth POTWs Typica l Standard Oxygen Transfer Rates Parameters f o r Scor ing C a p a b i l i t y o f C l a r i f i e r s i n

Suspended Growth POTWs Typical Ranges f o r Return Ac t iva ted S1 udge Pumping

Capaci t ies C r i t e r i a fo r Scor ing Sludge Handling Capab i l i t y f o r

Suspended Growth POTWs Typical U n i t S1 udge Product ion Val ues f o r Suspended

Growth POTWs Typical S1 udge Concentrations f o r Suspended Growth

POTW s Guide1 ines f o r Eval ua t ing Capaci ty o f E x i s t i n g S1 udge

Handling Processes M i s c e l l aneous U n i t Val ues Used i n Eval ua t i ng Capacity

o f Sludge Handling C a p a b i l i t y Suspended Growth Major Uni t Process Capacity Eval ua t i on Parameters f o r Scor ing Aerator Capabil i ty f o r T r i c k l i n g

F i l t e r POTWs Parameters f o r Scor ing Aerator C a p a b i l i t y f o r RBC POTWs Parameters f o r Scoring Aerator Capab i l i t y f o r ABF POTWs Parameters f o r Scoring C a p a b i l i t y o f C l a r i f i e r s i n T r i c k l i n g F i l t e r s and RBCs C r i t e r i a f o r Scoring S1 udge Handling Capab i l i t y f o r

Typical U n i t S1 udge Product ion Val ues and Sludge

T r i ck1 i n g F i l t e r Major U n i t Process ,Capacity Eval u a t i o n RBC Major U n i t Process Capacity Eval u a t i o n ABF Major U n i t Process Capaci ty Eval u a t i o n Typical Mean Cel l Residence Times f o r Suspended Growth

Suspended Growth Major U n i t Process Capacity Eval ua t ion

F ixed F i l m POTWs

Concentrations f o r F ixed F i l m POTWs

POTW s

f o r Example CPE

Typical Costs f o r Conducting a CCP

Typical CCP F a c i l i t a t o r Involvement Process Control Mon i to r ing a t a Small Ac t iva ted

Sludge P lan t

9 13

18

26 27

29

30

31

32

33

34

35 36

38 39 40

41

42

43 44 44 44

51

67

76

80

98

v i i i

LIST OF TABLES (cont inued)

Number Paqe

c-1 S p r i n g f i e l d, KS POTW Major U n i t Process Eva1 u a t i o n 132 c -2 Sp r ing f i e ld , KS POTW Capacity P o t e n t i a l 133

E - 1 Worksheet f o r Ca lcu la t i on o f Power Factor 183

F-1 Typica l Values o f Alpha Used f o r Es t imat ing AOR/SOR 187 F -2 Oxygen Sa tu ra t i on a t Standard Pressure and Actual

Water Temperature 188

i x

CHAPTER 1

INTRODUCTION

1.1 Purpose and Scope

This Handbook provides in fo rmat ion on methods t o economically improve t h e performance o f e x i s t i n g p u b l i c l y owned treatment works (POTWs). It i s ''how-to" o r i en ted and descr ibes an approach t h a t POTW owners can use t o achieve improvements i n t reatment w i thout major c a p i t a l expenditures. The approach cons is t s o f an eva lua t ion phase and a performance improvement phase.

The ev'aluat ion phase i s a thorough review and ana lys is o f a POTW's design c a p a b i l i t i e s and associated admin is t ra t ion , operat ion, and maintenance prac t ices . It i s conducted t o p rov ide in fo rmat ion f o r POTW admin is t ra to rs t o make dec is ions regard ing e f f o r t s necessary t o improve performance. The pr imary o b j e c t i v e i s t o determine i f s i g n i f i c a n t improvements i n t reatment can be achieved w i thou t making major cap4 t a l expenditures. This o b j e c t i v e i s accomplished by assessing t h e c a p a b i l i t y o f major u n i t processes and by i d e n t i f y i n g and p r i o r i t i z i n g those f a c t o r s t h a t l i m i t performance and can be co r rec ted t o improve performance.

The performance improvement phase i s a systemat ic approach t o e l i m i n a t i n g those f a c t o r s t h a t l i m i t performance i n e x i s t i n g POTWs. I t s major b e n e f i t i s t h a t i t opt imizes t h e c a p a b i l i t y o f e x i s t i n g f a c i l i t i e s t o perform b e t t e r and/ o r t r e a t more wastewater.

Th is document has been prepared f o r the b e n e f i t o f POTW owners and admin is t ra tors . It i s expected t h a t consu l tan ts f o r POTWs, regu la to ry personnel, and admin is t ra to rs o f p r i v a t e l y owned t reatment works w i l l a lso f i n d the in fo rmat ion usefu l . Th is Handbook focuses on POTWs t r e a t i n g t y p i c a l municipal wastewater compat ib le w i t h common b i o l o g i c a l wastewater t reatment . It has been w r i t t e n main ly f o r POTWs w i t h flows up t o about 40,000

Uni ted States (1). The scope o f t h e Handbook i s f u r the r focused on mechanical p l a n t s us ing ac t i va ted sludge (suspended growth), t r i c k l i n g f i l t e r s ( f i x e d f i l m ) , and v a r i a t i o n s o f these processes f o r secondary t reatment. Va r ia t i ons o f suspended growth processes inc luded are:

m p5°ces /d (10 ses mgd), which inc ludes over 95 percent of e x i s t i n g POlWs i n the

- P lug f l o w - Contact s t a b i l i z a t i o n - Ox ida t ion d i tches -- Complete mix - Tapered ae ra t i on - Step feed - Extended ae ra t i on

1

Fixed f i l m Drocesses inc luded a r e :

- Conventional rock f i 1 t e r s - Ac t iva ted b i o f i l t e r s (ABFs) - P l a s t i c media f i l t e r s - Rotat ing b i o l o g i c a l con tac tors (RBCs) - Redwood media f i l t e r s

1.2 Background

A 1980 General Accounting O f f i c e r e p o r t i nd i ca ted t h a t 87 percent o f 242 POTWs surveyed were i n v i o l a t i o n o f t he e f f l u e n t requirements i n t h e i r d ischarge pe rm i t ( 2 ) . A t 9 o f the 15 POTWs studied f u r t h e r , ope ra t i on and maintenance

'problems were determined t o be a s i g n i f i c a n t cause o f poor performance. A comprehensive na t iona l study t o i d e n t i f y and q u a n t i f y the s p e c i f i c causes o f inadequate POTW performance was conducted i n t h e l a t e 1970s (3-6). This study, i n v o l v i n g s i t e v i s i t s t o 287 f a c i l i t i e s and d e t a i l e d evaluat ions o f 103 o f these f a c i l i t i e s , i d e n t i f i e d t h e most predominant problems a t POTWs. The top f a c t o r s i d e n t i f i e d inc luded problems i n a l l four major areas t h a t a f f e c t p l a n t performance: design, admin i s t ra t i on , operat ion, and maintenance. A major conc lus ion from t h i s study i s t h a t each POTW usua l l y has a number o f perfoimance-1 i m i t i n g problems t h a t are unique t o t h a t f a c i l i t y .

I n response t o these needs, a program t h a t e f f e c t i v e l y e l im ina tes a l l performance-1 i m i t i n g fac to rs a t an i n d i v i d u a l POTW has been devel oped and demonstrated. It i s c a l l e d t h e Composite Cor rec t ion Program (CCP) because i t b r i n g s together the p o s i t i v e fea tures of many i n d i v i d u a l programs t o c o r r e c t a l l the s p e c i f i c per fo rmance- l im i t ing problems i d e n t i f i e d a t a sub jec t p lan t .

CCPs have been successfu l ly demonstrated a t a number o f f a c i l i t i e s (6-8). The most successful of these demonstrations have occurred i n POTWs where a combination o f minor design changes, process adjustments, operator t r a i n i n g , and appropr ia te admin i s t ra t i ve ac t ions 1 ed t o improving p l an t performance t o the des i red l e v e l .

App l i ca t i on o f t h e CCP approach has been made more a t t r a c t i v e by recen t congressional act ions. I n December 1981, t h e EPA Const ruc t ion Grants Program was changed t o p rov ide ( s t a r t i n g October 1984) f o r 55 percent ra the r than 75 percent as the Federal funding share f o r POTW c o n s t r u c t i o n (9 ) . I n add i t ion , t he Federal share o f p lanning and design phases w i l l no t be p a i d u n t i l t h e cons t ruc t i on phase i s approved and funded (10) . These changes, and t rends a t both t h e na t iona l and State l e v e l s , make i t more impor tant than ever t o achieve maximum u t i l i z a t i o n o f e x i s t i n g f a c i l i t i e s and t o avoid o r delay the need f o r capi t a l improvement p ro jec ts .

It i s apparent t h a t improved performance i s n o t achievable i n some f a c i l i t i e s w i thou t making s i g n i f i c a n t c a p i t a l improvements. To i d e n t i f y f a c i l i t i e s where performance cou ld be improved us ing a nonconstruction-oriented approach, a Comprehensive Performance Eva1 u a t i o n (CPE 1 phase was devel oped. A CPE i s performed t o determine i f a CCP cou ld r e s u l t i n s i g n i f i c a n t improvement i n p l an t performance and/or capaci ty .

2

The 1981 changes to the E P A Construction Grants Program also added the requirement t h a t , one year a f t r being placed i n operation, grantees e i ther cer t i fy t h a t their f a c i l i t i e s are capable of meeting the treatment levels for which they were designed or propose a corrective course of action (10). A CPE, w i t h i t s emphasis on identification of problems, and a C C P , w i t h i t s emphasis on making existing p l a n t s perform t o t he i r optimum level , can be valuable t o o l s f o r POTW owners t o use i n satisfying t h i s g r a n t requirement.

1.3 Overview

Many par t ies are involved i n achieving optimum performance from wastewater treatment f a c i l i t i e s (11). The following discussion provides perspective t o the roles of these parties.

A recent project conducted t o develop a strategy t o improve POTW Derformance and achieve compliance w i t h effluent permit requirements concluded t h a t local owners and administrators of wastewater treatment f a c i l i t i e s should be made more aware t h a t they are clearly responsible for the i r p lan t ' s performance ( 8 ) . . Compliance w i t h effluent permit requirements was found t o be o n l y a secondary objective o f many local administrators. Often the i r primary concerns were obtaining facil i t y grants, avoiding problems w i t h State and Federal regulatory personnel, and providing safe working conditions f o r empl oyees. A1 though each of these concerns i s important , 1 oca1 facil i t y administrators must recognize tha t t he i r primary objective i n treating wastewater i s t o achieve the required effluent q u a l i t y . Once local p r io r i t i e s have been focused toward cost-effectively achieving adequate treatment , owners can direct their technical staffs or consultants toward the ultimate goal . Technical assistance i s available from a variety of sources: engineers, operators, suppliers, contractors, t ra iners , contract operators, and financial consultants.

I t i s assumed tha t POTW owners and adninistrators have already recognized a need to improve the performance of the i r wastewater treatment f a c i l i t i e s and will use this Handbook to economically accomplish the required wastewater ef f l uent qual i ty .

1.4 References

When an NTIS number is cited i n a reference, t h a t reference is available from:

National Technical Information Service 5285 Port Royal Road S p r i n g f i el d , VA 22161 (703) 487-4650

3

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

The 1980 Needs Survey - Conveyance, Treatment and Control o f Municipal Wastewater, Combined Sewer Overflows , and Stormwater Runoffs, Summary of

Environmental P ro tec t i on Agency, O f f i ce o f Water Program Operations, Washington, DC, 1981.

Technical Data. EPA-430/9-81-008, NTIS NO. PB-82-131533, U.S.

Cost ly Wastewater Treatment P l a n t s F a i l t o Perform as Expected. CED-81-9, Report by t h e Comptrol ler General o f t h e Uni ted States, Washington, DC, 1980.

Hegg, B. A. , K. L. Rakness, and J. R. Schultz. Evaluat ion o f Operat ion and Maintenance Factors L i m i t i n g Municipal Wastewater Treatment P l a n t Performance. EPA-600/2-79-034, N T I S No. PB-300331, U.S. Environmental P r o t e c t i on Agency , Mun i c i pal Env i ro nmental Research Lab0 r a t o r y , C i n c i n n a t i , OH, 1979.

Gray, A. C. , J r . , P. E. Paul , and H. D. Roberts. Evaluat ion o f Operat ion and Maintenance Factors L i m i t i n g B i o l o g i c a l Wastewater Treatment P1 ant Performance. EPA-600/2-79-087, N T I S No. PB-297491, U.S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C i n c i n n a t i , OH, 1979.

Hegg, B. A,, K. L. Rakness, J. R. Schul tz, and L. D. Demers. Evaluat ion o f Operation and. Maintenance Factors L i m i t i n g Municipal Wastewater Treatment P l a n t Performance - Phase 11. EPA-600/2-80-129, NT IS No. PB-81-112864, U.S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1980.

Hegg, B. A., K. L. Rakness, and J. R. Schul tz. A Demonstrated Approach f o r Improving Performance and R e l i a b i l i t y o f B i o l o g i c a l Wastewater

Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1979.

Treatment P1 ants. EPA-600/2-79-035, NTIS NO. PB-300476, U.S.

Hegg, B. A., K. L. Rakness, and J . R. Schultz. The CCP Way t o B e t t e r E f f l uents. Water Engineering and Management, 12910 40-43, September 1982.

Schultz, J. R., 6. A. Hegg, and C. S. Zickefoose. Colorado CCP Demonstration and Development o f Areawide Compl iance Strategy. D r a f t r e p o r t , U. S. Environmental P r o t e c t i o n Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1983.

Municipal Wastewater Treatment Construct ion Grant Amendments o f 1981. P u b l i c Law 97-117, December 29, 1981.

Grants f o r Construct ion o f Treatment Works; I n t e r i m and Proposed Rules. 40 CFR P a r t 35, Vol. 47, No. 92, May 12, 1982.

11.. H i l l , W. R. , T. M. Regan, and C. S. Zickefoose. Operation and Maintenance o f Water P o l l l i t i o n Control F a c i l i t i e s - A WPCF White Paper. JWPCF 51~899-906, 1979.

4

CHAPTER 2

APPROACH TO CONDUCT I NG COMPR EHENS I VE PERFORMANCE EVALUATIONS

2.1 Ob jec t ive

The o b j e c t i v e o f a Comprehensive Performance Eva lua t ion (CPE) i s t o e s t a b l i s h whether a major f a c i l i t y upgrade i s necessary o r i f a Composite Cor rec t i on Program (CCP) i s capable o f producing the des i red e f f l u e n t qua1GL’ -

2.2 Methodology

A CPE achieves the above o b j e c t i v e through several a c t i v i t i e s : eva lua t ion o f the major u n i t processes; i d e n t i f i c a t i o n o f a1 1 performance- l imi t i n g fac to rs ; p r i o r i t i z a t i o n o f performance-1 i m i t i n g factors ; assessment o f a b i l i t y to improve performance w i th a CCP; and r e p o r t i n g CPE r e s u l t s . Althouqh these are d i s t i n c t a c t i v i t i e s , some o f them are conducted concur ren t ly with others. For example, eva lua t i on o f the major u n i t processes and i d e n t i f i c a t i o n o f performance-1 i m i t i n g f a c t o r s are genera l l y conducted a t t he same time.

Although t h i s Handbook presents a l l t h e i n fo rma t ion requ i red t o conduct a CPE, many references are a v a i l a b l e on techniques f o r eva lua t ion o f t reatment p l a n t performance, r e l i a b i l i t y , e tc . (1-14). It i s recommended t h a t these references be consul ted f o r f u r t h e r s p e c i f i c s on the subject .

2.2.1 Evaluat ion o f Major U n i t Processes

Major u n i t processes are evaluated t o assess the general a b i l i t y o f the CCP approach, as opposed t o a major cons t ruc t i on approach, to achieve des i red performance l e v e l s . If the CPE i n d i c a t e s t h a t the major u n i t processes a re adequate, a major p l a n t expansion o r upgrade i s n o t necessary and a p roper l y conducted CCP should achieve the des i red performance. I f , on the o ther hand, the CPE shows t h a t major u n i t processes are inadequate, owners should consider the expansion o f these processes as the focus fo r achieving des i red performance.

Resul ts o f eva lua t ion o f major u n i t processes can be summarized b y c a t e g o r i z a t i o n o f p l a n t type, as i l l u s t r a t e d i n F igu re 2-1.

5

FIGURE 2-1

CPE/CCP SCHEMATIC OF ACTIVITIES

, Type 1 Type 2

Major Unit Processes Major Unit Processes Are Adequate Are Marginal

P O W Administrators Recognize Need To

Improve Plant Performance

r 1

CPE Evaluation of

Major Unit Processes

Upgrade c

Type 3 Major Unit Processes I Are Inadequate

Do Not Implement CCP- Evaluate Options for a

Major Upgrade Including Facility and Financing

Alternatives

I

Type 1 p l a n t s are those POTWs where a CPE shows tha t current performance d i f f i cu l t i e s are not caused by l imitations i n the size or capabi l i t ies of the existing major u n i t processes. In these cases, the major problems are related t o p l a n t operation, maintenance, or administration, or t o problems t h a t can be corrected w i t h only minor f ac i l i t y modifications. POTWs t ha t f a l l i n t o t h i s category are most l ikely to achieve desired performance through the imp: ementation of a nonconstruction-ori ented CCP.

Identification of a POTW a s Type 2 represents a si tuation where the marginal capacity o f major u n i t processes will potentially prohibit the ab i l i ty to achieve the desired performance level. For Type 2 f a c i l i t i e s , implementation of a C C P will lead to improved performance b u t may not achieve required performance levels without significant physical p l a n t improvements.

A Type 3 p l a n t i s one i n which the existinq major u n i t processes are inadequate. A1 t h o u g h other 1 imi t i n g factors may ex i s t , such as the operators' process control capability, minor design features, o r the administration's unfamil i ari t y w i t h pl a n t needs, performance cannot be expected to improve significantly u n t i l Dhysical 1 imitations of major u n i t processes are el iminated. In this case, implementation of a nonconstruction-oriented C C P i s of limited value and i s n o t recommended. Owners w i t h a Type 3 f a c i l i t y would best meet the i r needs by p u r s u i n g development of wastewater treatment f a c i l i t i e s suitable for handling present and future waste loads as well as addressing factors identified i n the CPE. A more detailed study of treatment a1 ternatives and financing mechanisms would be warranted. CPEs t h a t identify Type 3 f a c i l i t i e s are s t i l l of benefit t o POTW administrators i n tha t the need for construction i s clearly defined f o r f a c i l i t y owners. A d d i t i o n a l l y , the C P E provides an understanding of the capabi l i t ies and weaknesses of existing operation and maintenance practices and administrative pol ic ies . POTW owners can use this information to evaluate use of existing f a c i l i t i e s as part of any major p l a n t upgrade and as a guide1 ine for optimizing operation, maintenance, and admini stration.

2.2.2 Identification of Performance-Limi t i n g Factors

Whereas the evaluation of major u n i t processes i n a plant i s used t o broadly categorize performance potential by assessing only 'physical f a c i l i t i e s , the identification of performance-1 imi t i n g factors focuses on one f a c i l i t y and the factors unique to tha t f ac i l i t y .

To ass i s t i n th i s identification, a l i s t of 70 different factors t ha t could potentially l imit a POTW's performance i s provided f n Appendix A (1). These factors are divided i n t o the categories of administration, maintenance, design, and operation. Suggested definit ions of each factor are also provided. T h i s l i s t was developed as a resu l t of many plant studies and i s provided for convenience and reference. If a1 ternate names or definit ions provide a c learer understanding to those involved i n conducting a C P E , they shou ld be used instead. If different terms are used, each factor should be defined and these definit ions should be readily available to those conductinq the CPE and those interpreting the resul ts .

7

Note t h a t the l i s t includes factors on capacity of major u n i t processes. If the evaluation o f major u n i t processes resu l t s i n a Type 2 or Type 3 c lassi f icat ion, these same limitations shou ld be documented i n the l i s t of factors 1 imi t i n g the POTW's performance. Completing the identification of factors is d i f f i c u l t i n t h a t true problems i n a POTW are often masked. This concept i s i l lus t ra ted i n t h e following discussion.

A contact stabil ization p l a n t was routinely losing sludge solids over the final c l a r i f i e r weirs, through the chlorine contact tank, and t o the receiving stream, resulting i n noncompliance w i t h the plant ' s permit. I n i t i a l observations could lead t o the conclusion t h a t the p l a n t had an inadequately sized final c l a r i f i e r . However, further investigation indicated t h a t the solids lo s s was a resu l t of the operator 's routinely wasting less sludge than was produced. I t was determined t h a t , t o properly control the sludge mass, increased operator time and additional equipment to adequately monitor and waste activated sludge to the digester would be required. I t was further determined tha t the digester was undersized and would not provide adequate residence time f o r complete digestion.

The most obvious problem i s the operator's lack of knowledge of how t o apply the concept of sludge mass control. The needed labora tory equipment was w i t h i n the approved budget for the f ac i l i t y and therefore was not assessed as a major problem. Plant administrators indicated tha t they could not afford additional operator time. This administrative pol icy was a significant factor 1 i m i t i n g performance. The undersized digester was not a significant problem i n this case because unlimited cropland for disposal of par t ia l ly digested sludqe was avail ab1 e. (Note: Disposal of par t ia l ly digested sludge on cropland can no longer be considered a permanent solution since enactment of Federal regulations for land disposal of POTW sludges) . I t was concluded t h a t four factors contributed to the solids loss t ha t caused poor p l a n t ef f l uent qual i ty:

1. Inadequate operator knowledge to apply the concept of sludqe mass control.

2. Restrictive adninistrative pol icy tha t prohibited needed opera to r t i me.

3. Inadequate test equipment.

4. Inadequate digester capacity.

The above discussion i l l u s t r a t e s t h a t a comprehensive analysis of a performance problem i s essential to identify the true performance-1 imi t i n g factors. If the in i t ia l obvious problem of lack of c l a r i f i e r capacity had been ident i f ied, improper corrective actions and unnecessary expenditures o f funds would likely have occurred. In almost a l l CPEs, several factors are identified as 1 i m i t i n g performance. I n i t i a l l y , each factor identified should be listed w i t h o u t regard to order of severity.

8

It i s emphasized t h a t the purpose o f i d e n t i f y i n g Derformance-l imi t i n q f a c t o r s i s to i d e n t i f y , as accurate ly as poss ib le , causes o f poor performance unique t o a p a r t i c u l a r p l a n t . Observation t h a t a f a c t o r does n o t meet the " i n d u s t r y standard'' does n o t n e c e s s a r i l y c o n s t i t u t e cause f o r i d e n t i f y i n g t h a t f a c t o r as 1 i m i t i n q the POTW I s performance. An actual l i n k between Door p l a n t performance and an i d e n t i f i e d f a c t o r must e x i s t .

2.2.3 P r i o r i t i z a t i o n o f Performance-Limi t i n g Fac to rs

A f t e r t h e f a c t o r s t h a t l i m i t performance have been i d e n t i f i e d , they are p r i o r i t i z e d as t o t h e i r adverse e f f e c t on achieving des i red p l a n t performance. The purposes o f t h i s p r i o r i t i z a t i o n are t o e s t a b l i s h t h e type o f fo l lowup a c t i v i t i e s necessary t o achieve compliance and the emphasis t h a t would have t o be p u t on each fac to r . I f t h e h ighes t rank ing factors , i .e. , those having t h e most negat ive impact on performance, a r e r e l a t e d t o phys ica l l i m i t a t i o n s i n u n i t process capac i t y , i n i t i a l c o r r e c t i v e ac t i ons are d i r e c t e d toward de f i n ing p l a n t m o d i f i c a t i o n s and ob ta in ing a d m i n i s t r a t i v e funding and a c t i o n f o r t h e i r imp1 m e n t a t i o n . I f the h ighes t rank ing f a c t o r s are process c o n t r o l o r i en ted , the i n i t i a l emphasis o f fo l lowup a c t i v i t i e s would be d i r e c t e d toward p l ant-speci f i c operator t r a i n i n g .

The p r i o r i t i z a t i o n o f f ac to rs i s accomplished by a two-step process. F i r s t , a l l f a c t o r s t h a t have been i d e n t i f i e d a re i n d i v i d u a l l y assessed w i t h regard t o adverse impact on p l a n t performance (Table 2-11; second, those f a c t o r s r e c e i v i n g "A 'S ' ' and " B ' s " a r e l i s t e d i n order o f p r i o r i t y .

TABLE 2-1

CLASSIFICATION SYSTEM FOR P R I O R I T I Z I N G PERFORMANCE-LIMITING FACTORS

R a t i n g

A

B

C

Adverse E f f e c t of F a c t o r on P l a n t Performance

Major e f f e c t on long-term r e p e t i t i v e b a s i s

Minimum e f f e c t on r o u t i n e bas i s o r major e f f e c t on a p e r i o d i c bas i s

M i n o r e f f e d t

Each f a c t o r p rev ious l y i d e n t i f i e d as l i m i t i n g performance i s now assigned an "A," -''By" o r "C" r a t i n g . The c h e c k l i s t o f f a c t o r s i n Appendix A inc ludes a column to en te r t h i s r a t i n g .

9

The factors that receive an "A" are the major problems tha t cause a performance deficiency. They should be the central focus of any subsequent program t o improve p l a n t performance. An example of an ' ' A " factor would be "ultimate sludge d i sposa l " f a c i l i t i e s , i .e. , dry ing beds, t h a t are too small t o allow routine wast ing of sludge from an activated sludge POTW.

All "6" factors ( a s well as ' 'A's") typically m u s t be eliminated before a p l a n t will achieve consistent desired performance. Two categories of factors receive a I 'B" r a t i n g :

1. Those t h a t routinely contribute to poor plant performance b u t are not the major problems. An example would be a shortage o f person-hours to ccmplete required process control testing i n a small activated sludge p l a n t where the underlying problem i s t h a t the operator does n o t understand how t o r u n o r interpret the tests o r understand the need for a better tes t ing program.

2. Those t h a t cause a major degradation of p l a n t performance, b u t o n l y on a periodic bas i s . Typical examples are an inadequate spare parts inventory tha t causes excessive process downtime once or twice a year, or marginal oxygen transfer capacity t h a t causes an oxygen shortage only d u r i n g the hot tes t month of the year. As a comparison, the example "A" factor above ("ult imate sludge disposal") would receive a "6" rating i f adequate drying bed capacity were available i n the summer b u t winter weather inhibited d r y i n g bed use.

Factors tha t receive a " C " r a t i n g can be shown to contribute to a performance problem b u t their e f fec t i s minor. They would l ike ly be corrected w i t h l i t t l e e f fo r t and/or time d u r i n g followup ac t iv i t i e s . For example, i f a c r i t i ca l process stream were accessible, b u t d i f f i c u l t t o sample, i t c o u l d indirectly contribute b poor performance by making process control l e s s convenient and more time consuming. The problem would n o t be a major focus of a subsequent corrective program. As a further comparison, the example " A " factor above ( " u l t i m a t e s ludge disposal") would receive a " C a m r a t i n g i f adequate drying bed capacity were available b u t cleaning the beds w i t h a f ron t loader has crushed several underdrain t i l e s .

In the i l l u s t r a t ion presented i n Section 2.2.2, "inadequate operator knowledge t o apply the concept of sludge mass control" i s assigned an ''A" because of i t s continuous detrimental e f fec t on p l a n t performance; "adninistrative pol icy" a "6" because of i t s routinet e f fec t ; and "testing equipment" a ' IC" because i t s e f fec t i s only a minor contributing factor. "Inadequate digester size" i s given a "6" because i t made proper sludge mass control more d i f f i cu l t and labor intensive. I t i s not given an "A" because i t d i d n o t limit performance i n a major way since adequate sludge disposal capacity i s available by u t i l i z i n g nearby cropland.

Once each identified factor i s assessed individually and assigned an ''A," ' ' B y " o r "C" classif icat ion, those receiving "A's" and "6 's ' ' are l i s t ed on a one-page summary sheet i n order of priority. This requires t h a t the evaluator assess a l l the "A'S'' and I lBIsl l t o determine the most serious cause of poor performance, second most serious, etc. A summary sheet f o r r ank ing the

10

p r i o r i t i z e d f a c t o r s l i m i t i n g p l a n t performance i n order o f s e v e r i t y i s presented i n Appendix B. This process i s e f f e c t i v e i n reducing the i d e n t i f i e d fac to rs t o a one-page summary and serves as a va luab le re ference f o r the nex t step o f the CPE: assessing a b i l i t y t o improve p l a n t performance.

2.2.4 Assessing Ab i l i ty t o Improve Performance

By d e f i n i t i o n o f a CCP, a l l per fo rmance- l im i t ing f a c t o r s can t h e o r e t i c a l l y be e l iminated. Nevertheless, i t i s necessary to s p e c i f i c a l l y assess the a b i l i t y o f a CCP to improve performance i n each POlW. An e f f e c t i v e approach i s t o eval uate each i d e n t i f i e d f a c t o r i n d i v i d u a l l y t o determine whether there are any p r a c t i c a l reasons a f a c t o r cannot be addressed. Examples o f f ac to rs t h a t may n o t be feas ib le to address a re replacement of key personnel , d r a s t i c increases i n funding, o r extensive t r a i n i n g o f owners o r admin is t ra to rs t o support POTW needs.

Some f a c t o r s have a v a r i e t y of p o t e n t i a l so lu t i ons o r combinations o f c o r r e c t i v e ac t ions t h a t can e f f e c t i v e l y address the problem. For example, an a c t i v a t e d sludge c l a r i f i e r may be improved by i n s t a l l i n g b a f f l e s t o decrease s h o r t k i r c u i t i n g , by u t i l i z i n g p a r t i a l f l o w equa l i za t i on to reduce hydraul i c peaks, o r by swi tch ing t o o ther ac t i va ted sludge mass modes t o b e t t e r con t ro l sludge s e t t l i n g c h a r a c t e r i s t i c s and t o reduce c l a r i f i e r loading. Often a combinat ion o f these c o r r e c t i v e ac t ions would be appropr iate. The systematic assessment o f the p r i o r i t i z e d factors helps assure t h a t a l l f ac to rs can r e a l i s t i c a l l y be addressed, thus p rov id ing the bas is f o r the comprehensive approach t o improving performance.

It i s the p r i o r i t i z a t i o n and assessment phase o f a CPE t h a t requ i res maximum a p p l i c a t i o n o f the evaluators ' judgment and experience. It should be noted t h a t i t i s o f t e n necessary t o l a t e r modify the o r i g i n a l c o r r e c t i v e steps and requirements as new o r add i t i ona l i n fo rma t ion becomes a v a i l ab le dur ing the conduct o f a CCP phase.

A CPE conducted a t an ac t i va ted sludge p l a n t i d e n t i f i e d t h e major performance-1 i m i t i n g f a c t o r s as:

This concept i s i l l u s t r a t e d by the fo l l ow ing :

1. Inadequate operator understanding t o make process adjustments t o c o n t r o l sludge s e t t l i n g c h a r a c t e r i s t i c s .

2. Inadequate s t a f f i n g t o make operat ional adjustments.

3. Inadequate program t o keep equipment func t i on ing cont inuously .

Based on these fac to rs , a CCP was implemented to improve performance o f the e x i s t i n g f a c i l i t i e s . It was decided t h a t t h i s p l a n t cou ld perform bes t when the a c t i v a t e d sludge s e t t l i n g r a t e was r e l a t i v e l y slow. The p l a n t ope ra to r ' s understanding was improved through t r a i n i n g , and he became capable of making process c o n t r o l adjustments to achieve the des i red slower sludge s e t t l i n g rate. Once the des i red slower sludge s e t t l i n g r a t e was achieved, poor c l a r i f i e r performance was observed and

11

effluent quality deteriorated. Further investigation indicated t h a t modifications made a year ea r l i e r t o the c l a r i f i e r i n l e t baffles were a1 lowing short-circuiting t o occur. This short-circuiting only became apparent a f te r the slower set t l ing had been achieved. These baff le modifications were reassessed and changed to reduce short-circui t i n 9 and e f f l uent quality improved dramatical l y .

In t h i s i l l u s t r a t ion , a minor design modification was determined to be a performance-limiting factor. This factor was not identified i n the oriqinal C P E . An awareness tha t i t may not be possible to identify a l l performance- l i m i t i n g factors i n the C P E , as well as an awareness t h a t the CCP approach allows fur ther definition and identification of factors d u r i n g i t s implementation, i s an important aspect of assessing a POTW's capabili ty t o achieve improved performance.

2.2.5 CPE Report

The resul ts of a CPE should be sunmarized i n a b r ie f , written report t o provide guidance for f ac i l i t y owners and administrators. An example i s included i n Appendix C. A typical C P E report i s 8-12 pages i n length and includes the following topics:

- Facil i t y background - Major process evaluation - Performance-limiting factors - Projected impact of a C C P - C C P costs

A CPE report should not provide a l i s t of specific recommendations for correcting individual performance-1 imi t i n g factors. T h i s often leads to a piecemeal approach to corrective actions h e r e the goal of improved performance i s not met. For Type 1 and Type 2 plants, the necessity of comprehensively addressing the combination of factors identified by the CPE through the implementation of a CCP should be stressed. For Type 3 p l a n t s , a recommendation for more detailed study to support the anticipated upgrade may be warranted.

2.3 Personnel Capabilities for Conducting CPEs

Persons responsible for conducting CPEs should have a know1 edge o f wastewater treatment, including the following areas:

- Regul atory requirements - Process control - Process design - Sampl i n g

- Microbiol ogy - - Laboratory testing

1 2

Hydraul i c p r i n c i p l e s Opera t o r t r a i n i ng Wastewater f a c i l i ty budget ing Safety Ma i n t e nance Man ag eme n t

Consul t i n g engineers who r o u t i n e l y work w i t h POTW design and s t a r t u p , and regu la to ry agency personnel w i t h experience i n eva lua t ing wastewater t reatment f a c i l i t i e s , represent the types o f personnel w i t h adequate backgrounds t o conduct CPEs. This Handbook i s no t intended as a quide to the design o r opera t ion o f POTWs.

2.4 Es t imat ing CPE Costs

The c o s t o f conduct ing a CPE depends on t h e s ize and type o f f a c i l i t y . Ac t iva ted sludge p lan ts tend to be more complex than t r i c k l i n g f i l t e r p l a n t s o r o ther f i x e d f i l m f a c i l i t i e s . Guidel ines f o r es t imat ing CPE cos ts and person-days a re presented i n Table 2-2. These est imates a re f o r con t rac t i nq w i t h aaconsul tant who normal ly performs t h i s type o f service. The c o s t to a community f o r conduct ing a CPE w i t h munic ipa l employees would probably be l e s s than the amounts shown i n Table 2-2. However, municipal employees may n o t have the necessary q u a l i f i c a t i o n s o r may be t o o c lose to the e x i s t i n g operat ion t o be able t o perform a t r u l y o b j e c t i v e evaluat ion.

TABLE 2-2

TYPICAL COSTS FOR CONDUCTING CPEsa

Type and S ize o f F a c i l i t y

Typica l Person-days Typical Cost

Onsi t e (1984 $1

Suspend d Growth:b,c ~ 8 0 0 a / d (9.2 mgd) 2 800-8,000 m / d (0.2-2 mgd) 8,000-38,000 d / d (2.0-10 mgd) 7

5 1,500- 3,000

4,000-16,000 2,000-10,000

F i xed Fi1m:d <2,000 $ /d (035 mgd) 2 1,500- 4,000 2,000-38,000 m /d (0.5-10 mgd) 5 3,000-1 2,000

aFor c o n t r a c t consu l tan t . b Inc ludes a1 1 v a r i a t i o n s o f ac t i va ted sludge. -cABF systems, which combine suspended and f i x e d growth, r e q u i r e an

dIncludes t r i c k l i n g f i l t e r s w i t h bo th p l a s t i c and rock media and WCs. e f f o r t s i m i l a r to ac t i va ted sludge.

1 3

n

2.5 References

When an N T I S number i s c i t e d i n a re ference, t h a t re ference i s ava i l ab le from:

Nat ional Technical In fo rmat ion Serv ice 5285 P o r t Royal Road Spr ing f i e ld , VA 22161 (703) 487-4650

1. Hegg, 6. A., K. L. Rakness, J. R. Schul tz, and L. D. Demers. Evaluat ion o f Operation and Maintenance Factors L i m i t i n g Municipal Wastewater Trealment P lan t Performance - Phase 11. EPA-600/2-80-129, N T I S No. P6-81-112864, U. S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1980.

2. Culp, G. L. and N. F. Helm. F i e l d Manual f o r Performance Eva lua t ion and Troubleshoot ing a t Municipal Wastewater Treatment F a c i l i t i e s . EPA-430/9-78-001, NTIS No. PB-279448, U.S. Environmental P ro tec t i on Agency, O f f i c e o f Water Program Operations, Washington, DC, 1978.

3. -Process Design Manual : Wastewater Treatment F a c i l i t i e s fo r Sewered Small Communi t i e s . EPA-625/1-77-009, U. S. Environmental P ro tec t i on Agency, Center f o r Environmental Research In format ion, C inc inna t i , OH, 1977.

4. H in r ichs , D. J. Inspectors Guide fo r Evaluat ion o f Municipal Wastewater

Environmental P ro tec t i on Agency, Of f i ce o f Water Program Operations, Washington, DC, 1979.

Treatment P1 ants. €PA-4 30/9 -7 9 -01 0, NT IS NO. PB -80 -1 3860 5, U . S .

5. Schultz, D. W . and V. B. Parr . Eva lua t ion and Documentation o f Mechanical R e l i a b i l i t y o f Conventional Wastewater Treatment P lan t Components. EPA-600/2-82-044, NT IS No. PB-82-227539, U.S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1982.

6. Niku, S., E. D. Schroeder, G. Tchobanoglous, and F. J . Samanieqo. Performance o f Ac t iva ted Sludge Processes: R e l i a b i l i t y , S t a b i l i t y and V a r i a b i l i ty. EPA-600/2-81-227, NT IS No. PB-82-108143, U.S. Environmental P ro tec t ion Agency, Mun i c i pal Environmental Research Lab0 r a tory, C inc inna t i , OH, 1981.

7. Haugh, R., S. Niku, E. D. Schroder, and G. Tchobanoglous. Performance o f Tr ick1 i n g F i l t e r Plants: R e l i a b i l i t y , S t a b i l i t y and V a r i a b i l i t y . EPA-600/2-81-228, NT IS No. PB 82-109174, U.S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C inc innat i , OH, 1981.

8. Handbook f o r a t Municipal Env i r o m e n t a Informat ion,

I d e n t i f i c a t i o n and Cor rec t i on o f Typica l Design De f i c ienc ies Wastewater Treatment F a c i l i t i e s . EPA-625/6-82-007. U. S.

P ro tec t i on Agency, Center f o r Environmental Research C inc innat i , OH, 1982.

14

9. B a l l , R. O., M. Ha r r i s , and K. Deeny. Evaluat ion and Control o f Sidestreams Generated i n Pub1 i c l y Owned Treatment Works. EPA-600/2 -82 -01 6 , NT I S No. PB -82 -1 952 72, U . S. Env i r o m e n t a1 Protec t i o n Agency, Municipal Environmental Research Laboratory, C inc innat i , OH, 1982.

10. Energy Management Diagnost ics. EPA-430/9-82-002, N T I S No. PB-82-198219, U.S. Environmental P ro tec t i on Agency, O f f i c e o f Water Program Operations, Washington, DC, 1982.

11. Comprehensive Diagnost ic Eva1 u a t i o n and Selected Management Issues. EPA-430/9-82-003, NTIS No. PB-82-212770, U. S. Environmental P ro tec t i on Agency, O f f i c e o f Water Program Operations, Washington, DC, 1982.

12. Contract Operations. EPA-430/9-82-004, NTIS No. PB-82-197161, U.S. Environmental P ro tec t i on Agency, O f f i c e o f Water Program Operations, Washington, DC, 1982.

13. Wastewater U t i l i ty Recordkeepi ng, Reportinq, and Management In fo rmat ion Systems . E PA-430 /9-82 -006, NT IS No. PB -83 -1093 48 , U. S. Env i r o nmen t a1 Pro tec t i on Agency, O f f i c e o f Water Program Operations, Washington, DC, 1'983.

14. New Engl and Wastewater Management Guide - U t i l i ty Management System. Ava i l ab le from the New England Water P o l l u t i o n Control Commission.

15

CHAPTER 3

HOW TO CONDUCT COMPREHENSIVE PERFORMANCE EVALUATIONS

3.1 I n t r o d u c t i o n

This chapter provides guidance f o r persons conducting Comprehensive Performance Evaluat ions (CPEs). If a person associated d i r e c t l y w i t h t h e POTW i s the evaluator conducting the CPE, some o f the steps may n o t be necessary.

3.2 I n i t i a l A c t i v i t i e s

To determine t h e magnitude o f t h e f ie ldwork requi red, and t o make t h e o n s i t e a c t i v i t i e s most product ive, as much i n i t i a l in fo rmat ion as poss ib le should be gathered by telephone. This in fo rmat ion inc ludes bas ic data on t h e POTW and sources f o r any needed add i t iona l in format ion.

3.2.1 Personnel

The eva lua tor should obta in the names o f those persons associated w i t h the POW who w i l l be t h e primary sources o f in fo rmat ion f o r t h e CPE. The POTW superintendent, manager, o r o ther person i n charge o f the wastewater t reatment f a c i l i t y should be i d e n t i f i e d . I f d i f f e r e n t persons are responsib le f o r p l a n t maintenance and process c o n t r o l , they should a1 so be i d e n t i f i e d .

The person most knowledgeable about the d e t a i l s o f the POTW budget should be i d e n t i f i e d by name, p o s i t i o n , and physical loca t ion . A 1- t o 2-hour meeting w i t h t h i s person dur ing the f ie ldwork w i l l have to be scheduled t o ob ta in a copy o f t h e budget and discuss it. I n many small communities, t h i s person i s most o f t e n the c i t y c l e r k ; i n l a r g e r communities, the u t i l i t i e s d i r e c t o r , wastewater superintendent, o r person o f s i m i l a r t i t l e can usua l ly prov ide t h e b e s t in fo rmat ion on the budget.

The key a d m i n i s t r a t i v e person o r persons should a lso be i d e n t i f i e d . I n many small communities o r s a n i t a t i o n d i s t r i c t s , an operator o r p l a n t super intendent may r e p o r t d i r e c t l y t o the e lected governing a d m i n i s t r a t i v e body, u s u a l l y the c i t y counc 1 o r d i s t r i c t board. I n l a r g e r cmmuni t ies , t h e key acbnin is t ra t ive person i s o f t e n the d i r e c t o r o f p u b l i c works, c i t y manager, o r o ther nonelected acbninistrator. I n a l l cases, the acbnin is t ra tor (s) who has t h e a u t h o r i t y to e f f e c t a change i n p o l i c y o r budget f o r the POTW should be i d e n t i f i ed

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If a consu l t i ng engineer i s c u r r e n t l y invo lved w i t h the POTW, t h a t i n d i v i d u a l should be informed o f t h e CPE and be prov ided a copy o f the f i n a l r e p o r t f o r comment. Normally, t h e consu l t i ng engineer w i l l not be d i r e c t l y invo lved i n conduct o f the CPE. An except ion may occur i f the re i s an area o f t h e eval u a t i o n t h a t coul d be suppl emented by the exper t i se ava i l ab1 e through the consu l tan t .

3.2.2 Wastewater Treatment P1 an t

The i n i t i a l i n fo rma t ion conta ined i n Table 3-1 should be obtained by telephone t o est imate f i e l d t ime required. The p l a n t super intendent and/or c h i e f operator should be t h e contac t f o r t h i s in format ion. This in fo rmat ion should be c o l l e c t e d bear ing i n mind t h a t some of the data may l a t e r be found t o be inaccurate. Generally, t h e data t h a t a c h i e f operator can prov ide extemporaneously o r from a r e a d i l y a v a i l a b l e re ference i s s u f f i c i e n t a t t h i s time.

I r r e g u l a r i t i e s t h a t may warrant spec ia l cons idera t ion when p lanning o r conduct ing the f i e l dwork should be i d e n t i f i e d , and more s p e c i f i c quest ions shouldabe asked t o de f ine t h e p o t e n t i a l e f f e c t on t h e evaluat ion. Frequent ly occu r r i ng i r r e g u l a r i t i e s inc lude: major process o r pieces o f equipment out o f serv ice; key persons on vacat ion o r scheduled f o r o ther p r i o r i t y work; and new o r uncommon treatment *processes.

The s i n g l e t r i c k l i n g f i l t e r , a e r a t i o n basin, o r f i n a l c l a r i f i e r being out o f serv ice w i l l probably necess i ta te postponing f i e l dwork i n small p lants . I n p l a n t s w i t h two o r more dup l ica te u n i t processes, a CPE can be conducted w i t h one u n i t o u t o f serv ice i f t h e r e s u l t s o f t h e eva lua t ion are needed before normal opera t ion can be resumed.

3.2.3 Performance

An i n d i c a t i o n o f pas t p l a n t o v e r a l l performance should be obtained f rom p l a n t personnel. Most l i k e l y , a CPE w i l l n o t be conducted unless a performance problem i s a t l e a s t suspected. However, an eva lua tor should no t expect to l e a r n on the telephone t h e exact d e t a i l s of a performance problem. That i s , a f t e r a l l , t he purpose o f the CPE.

3.2.4 Scheduling

The major c r i t e r i o n f o r schedul ing the t ime f o r a CPE should be the a b i l i t y t o g e t commitment o f l o c a l personnel a v a i l a b i l i t y . Usual ly, one-hal f to two- th i rds o f the t ime scheduled f o r f ie ldwork w i l l r e q u i r e the a v a i l a b i l i t y and he lp o f these persons.

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TABLE 3-1

PRELIMINARY PLANT INFORMATION TO COLLECT BY TELEPHONE

P l a n t Name

Phone Contact

P o s i t i o n

Phone No. Date

Design Flow Cur ren t Flow

Serv ice Populat ion

Year P1 an t B u i l t

D i r e c t i o n s t o P lan t

Most Recent Upgrade

Major Processes ( t ype and s i ze ) :

Pre l i m i n ary t reatment

Pr imary t reatment

Secondary t reatment

Aera t ion bas i n

T r i c k 1 i n g f i l t e r

C1 a r i f i e r

D i s i n fec t i o n

S1 ud treatment

Unusual processes o r equipment

Any processes o r major equipment c u r r e n t l y n o t operat ional

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TABLE 3-1 (cont inued)

Who does performance m o n i t o r i n g t e s t s ?

Who does process c o n t r o l t e s t s ?

What process c o n t r o l t e s t equipment i s a v a i l a b l e ?

P1 a n t coverage (8 am-5 pm, 24 h r , e t c . )

Work hours o f key i n d i v i d u a l s

Known c o n f l i c t s w i t h schedul i n g f i e l dwork

Contact f o r schedul ing f i e 1 dwork

A d m i n i s t r a t o r o r owner ( respons ib le o f f i c i a l )

Who has records on the budget?

Who i s consul t a n t ?

I n f o r m a t i o n resources ( a v a i l a b i l i t y ) :

As-bui l t c o n s t r u c t i o n plans

O&M manual

Mon i to r i ng records

Equipment 1 i t e r a t u r e

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Scheduling should be coord inated w i t h the a v a i l a b i l i t y o f a t l e a s t the major process c o n t r o l decisionmaker , t h e major admin i s t ra t i ve deci sionmaker , and t h e person most knowledgeable o f the p l a n t budget. A commitment o f t ime from these key persons i s essent ia l t o the successful conduct o f a CPE. I t may a l so be b e n e f i c i a l t o in form State and Federal regu la to ry personnel o f the CPE schedule t o avoid poss ib le in te r fe rence w i t h enforcement a c t i v i t i e s . Respons ib i l i t y f o r t h i s task should be c l e a r l y i d e n t i f i e d between the evaluator and l o c a l personnel du r ing t h e schedul ing o f a c t i v i t i e s .

i lu r ing the f ie ldwork , t h e process c o n t r o l decisionmaker should be prepared t o devote a t l e a s t h a l f o f h i s /he r t ime to the evaluat ion. The admin i s t ra t i ve decisionmaker should be ava i l ab le f o r 1 hour f o r a k i c k o f f meeting, several hours f o r reviewing the budget, another several hours f o r t a l k i n g about general admin is t ra t ion , and 1-2 hours f o r a summary meeting.

The persons requ i red f o r t h e conduct o f a CPE are the eva lua tor should make every e f f o r t to inc lude a ensure success o f t he CPE.

o f ten very busy ; however , 1 necessary i n d i v i d u a l s t o

3.3 .Data C o l l e c t i o n

I n i t i a l o n s i t e CPE a c t i v i t i e s are l a r g e l y devoted t o c o l l e c t i o n o f data requ i red f o r l a t e r eva lua t ion o f the POTW. As a courtesy, and t o promote e f f i c i e n t data c o l l e c t i o n , t h e f ie ldwork i s i n i t i a t e d w i t h a k i c k o f f meeting and a p l a n t tour . These a c t i v i t i e s a r e fo l lowed by a per iod o f t ime where a l a rge amount o f d e t a i l e d data on t h e POTW i s gathered.

3.3.1 K i c k o f f Meeting

A s h o r t meeting o f key POTW personnel ( i n c l u d i n g key admin is t ra to rs ) and t h e eva lua to r should be he ld t o i n i t i a t e the f ie ldwork. The major purposes o f t h i s meeting are to exp la in and gain support f o r t h e CPE e f f o r t , t o coord ina te and e s t a b l i s h the schedule, and t o i n i t i a t e the admin i s t ra t i ve eva lua t i on a c t i v i t i e s . The ob jec t i ves o f t h e CPE should be presented along w i t h t h e proposed a c t i v i t i e s . Spec i f i c meeting t imes w i t h nonpl an t personnel should be scheduled. In format ion and resource requirements should be spel l e d ou t . Spec i f i c items t h a t a re requ i red and may n o t be r e a d i l y a v a i l a b l e are: budget in fo rmat ion t o p rov ide a complete overview of cos ts associated w i t h wastewater t reatment; schedule o f sewer use and tap charges; discharge pe rm i t (NPDES) f o r the POTW; h i s t o r i c a l mon i to r ing data ( 2 years ) ; u t i l i t y b i l l s (1 year ) ; sewer use ordinance ( i f app l icab le ) ; and any f a c i l i t y p lans o r o ther engineer ing s tud ies completed on t h e e x i s t i n g f a c i l i t y . Admin is t ra t i ve f a c t o r s should be noted dur ing t h i s meeting, such as the p r i o r i t y put on Emi t compliance, f a m i l i a r i t y w i t h p l a n t needs, and p o l i c i e s on increased funding. These i n i t i a l percept ions o f t e n prove va luable when formal ly eva lua t ing admin i s t ra t i ve f a c t o r s l a t e r i n the CPE e f f o r t .

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3 . 3 . 2 P l a n t Tour

A p l a n t tour should follow the kickoff meeting. The objectives of the t o u r are t o familiarize the evaluator w i t h the physical ' p l a n t , make a preliminary assessment of design operational f l ex ib i l i t y of the existing u n i t processes, and provide an i n i t i a l basis for discussions on performance, process control, and maintenance. A walk-through tour following the flow of wastewater i s suggested. I t i s then appropriate t o tour the sludge treatment and disposal f a c i l i t i e s , followed by the support f a c i l i t i e s such as maintenance areas and laboratories. The evaluator should note the sampling points established throughout the p l a n t for bo th process control and compliance moni t o r i n g . Suggestions t o help the evaluator meet the objectives of the p l a n t tour are provided i n the following sections.

3.3.2.1 Prel iminary Treatment

Major components of prel iminary treatment typical ly i ncl ude coarse screening o r comminution, gr i t removal, and flow measurement.

A1 t h o u g h inadequate screening rarely has a direct e f fec t on p l a n t Performance, i f , for example, surface mechanical aerators must be s h u t down twice a day to remove rags i n an activated sludge plant w i t h marginal oxygen transfer capacity, i t could become a siqni ficant performance-1 i m i t i n g factor. Screening could be an identified area tha t could improve performance w i t h minor design improvements ( a t l ea s t i n a small p l a n t t h a t could u t i l i ze hand- cleaned bar screens). Indications of screening problems are:

- P l u g g i n g ( w i t h rags) of raw sewage or primary sludge pumps

- P1 ugging of trick1 i n g f i l t e r dis t r ibutors

- Rag b u i l d u p on surface mechanical aerators

- P l u g g i n g of activated sludge return pumps where primary c l a r i f i e r s are not used

Grit removal generally only has an indirect e f fec t on plant performance. For example, inadequate gri t removal can cause excessive wear on pumps or other downstream equipment resulting i n excessive downtime, and rep1 acement/repair costs, and could deprive c r i t i ca l processes of needed operator time.

Raw wastewater flow measurement facil i t i e s are important to accurately establish plant loadings. The plant tour should be used to observe the primary measuring device and t o ask several questions regarding plant flows. If flow i s turbulent or nonsymmetrical through flumes and over weirs commonly used as primary flow measurement devices, the flow records are immediately questionable. I f flow i s nonturbulent and symmetrical, there i s a good chance the primary device is sufficiently accurate. The evaluator should always p l a n t o check the accuracy of flow measurement l a t e r d u r i n g the fieldwork.

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3.3.2.2 Primary C l a r i f i c a t i o n

The value o f pr imary c l a r i f i c a t i o n i n r e l a t i o n t o o v e r a l l p l a n t performance i s i n decreasing the load on subsequent secondary t reatment processes. As such, the evaluator should determine what performance mon i to r ing o f t he pr imary processes i s conducted. As a minimum, s u f f i c i e n t data to ca lcu la te averaqe BOD5 loadings on the secondary p o r t i o n o f t he p l a n t should be ava i lab le . The areas o f major concern t h a t should be discussed dur ing the tour are f l e x i b i l i ty a v a i l able f o r changing operat ional f unc t i ons and c l a r i f i e r pe info rma nce . The major operat ional va r iab le t h a t a f f e c t s pr imary c l a r i f i e r performance and can be c o n t r o l l e d i n most p l a n t s i s sludge removal. The evaluator should d iscuss the process con t ro l method used to ad jus t sludge withdrawal. I n general, pr imary c l a r i f i e r s work best w i t h a minimun o f sludqe i n t h e c l a r i f i e r ( low sludge de ten t ion times and low b lanke t l e v e l ) . The p r a c t i c a l l i m i t f o r min imiz ing the sludge i n t h e c l a r i f i e r i s when the sludge becomes t o o t h i n , i .e. , t o o much water f o r the sludge handl ing f a c i l i t i e s . A pr imary sludge concent ra t ion o f greater t han 5 percent t o t a l s o l i d s i s an i n d i c a t i o n t h a c primary c l a r i f i e r performance may be improved hy increased sludge pumpinq and warrants f u r t h e r i nves t i ga t i on . A pr imary sludge concent ra t ion o f l e s s than 3 percent t o t a l s o l i d s i nd i ca tes the re i s l i k e l y l i t t l e oppor tun i ty t o improve performance w i t h increased sludge pumping. The operat ional approach used t o improve primary c l a r i f i e r performance must be weighed against the impact on the s l udge hand1 i ng processes.

The surface over f low r a t e (SOR), which i s t h e d a i l y average f l o w d i v ided by c l a r i f i e r surface area (CSA), can be a good i n d i c a t o r o f the performance t h a t can be expected from a pr imary c l a r i f i e r hand l ing t y p i a1 domestic wastewater. A c l a r i f i e r operat ing a t an SOR o f l e s s than 25 %/m2/d (600 gpd/sq f t) w i l l t y p i c a l l y remove 35-45 percent o f t h e BOD5 i n domestic wastewater. A c l a r i f i e r operat ing a t an SOR o f 25-40 m3/m2/d (600-1,000 gpd/sq f t ) w i l l t y p i c a l l y remove 25-35 percent o f t h e BODS.

3.3.2.3 Aerator

The term "ae ra to r " i s used i n t h i s Handbook t o descr ibe the u n i t process t h a t prov ides the conversion o f d isso lved and suspended organic mat te r to s e t t l e a b l e microorganisms. Examples o f an aera tor are: ae ra t i on basin, t r i c k 1 i n g f i l t e r , and r o t a t i n g b i o l o g i c a l con tac tor (RBC). The aera tor represents a c r i t i c a l process i n t h e wastewater f l ow stream i n determining o v e r a l l p l a n t performance capabi l i ty. Eva1 u a t i o n o f POTW capabi l i ty w i l l r e q u i r e ca re fu l ana lys i s o f t he ae ra to r u n i t i n a l l p lants . Dur ing the p l a n t tour , t he eva lua tor should determine i f c u r r e n t operat ing cond i t ions represent normal cond i t i ons and i n q u i r e about what opera t iona l f l e x i b i l i t y i s ava i lab le . For example: Can t r i c k l i n g f i l t e r s be run i n p a r a l l e l as we l l as ser ies? Can r e c i r c u l a t i o n be provided around t h e f i l t e r o n l y ? Can ae ra t i on basins be operated i n a contac t s t a b i l i z a t i o n mode as we l l as p lug f low and complete m i x?

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3.3.2.4 Secondary C l a r i f i c a t i o n

I n a l l b i o l o g i c a l wastewater t reatment p lan ts , t h e main f u n c t i o n o f secondary c l a r i f i c a t i o n i s to separate the sludge s o l i d s from the t rea ted wastewater. Another purpose i s t o th icken the sludge be fore removal from t h e c l a r i f i e r . C h a r a c t e r i s t i c s t h a t should be noted on the p l a n t tour a re con f igu ra t i on , depth, and opera t iona l f l e x i b i l i t y .

The evaluator should note t h e general c o n f i g u r a t i o n o f t h e c l a r i f i e r , i nc lud ing shape, s l udge removal mechanism, and we i r and launder arrangement. A c i r c u l a r c l a r i f i e r w i t h a "donut" launder l oca ted several f e e t from t h e c l a r i f i e r w a l l and a siphon-type, r a p i d withdrawal sludge c o l l e c t o r t y p i c a l l y prov ides optimum performance. A long, narrow, rec tangu lar c l a r i f i e r w i t h e f f l u e n t we i rs on ly a t the end and countercurrent sludge removal should s ignal an immediate concern about c l a r i f i e r performance. C1 a r i f i e r s w i t h depth l e s s than 3 m (10 f t ) p rov ide l i m i t e d sludge storage and th icken ing c a p a b i l i t y and c rea te concerns about capac i ty , espec ia l l y i n a c t i v a t e d sludge p lan ts .

The SOR ca be used t o roughly est imate f i n a l c l a r i f i e r capaci ty. An SOR l e s s

c l a r i f i e r capaci ty. A s i g n i f i c a n t l y h igher SOR would mean t h a t o the r processes would have to be f a i r l y conserva t ive to make the system perform adequately, and they should be evaluated w i t h cons idera t ion o f t h i s h igher c l a r i f i e r loading.

than 25 m 3 /m2/d (600 gpd/sq f t ) f o r a c i r c u l a r c l a r i f i e r i nd i ca tes good

When t o u r i n q a c t i v a t e d sludge f a c i l i t i e s , t he eva lua tor should become f a m i l i a r w i t h operat ion and f l e x i b i l i t y o f t h e r e t u r n sludge scheme: how sludge i s withdrawn from the c l a r i f i e r ; a b i l i t y t o operate a t h igher o r lower loadings; a v a i l a b i l i t y o f r e t u r n sludge f l o w measurement; and f l e x i b i l i t y t o d i r e c t r e t u r n sludge to d i f f e r e n t ae ra t i on basins o r p o i n t s i n the f low stream.

3.3.2.5 D i s i n f e c t i o n

D i s i n f e c t i o n f a c i l i t i e s should be toured t o become f a m i l i a r w i t h the process and equipment a v a i l able and because inspec t i on o f d i s i n f e c t i o n f a c i l i t i e s o f t e n provides i n s i g h t i n t o performance o f the secondary t reatment process. Where d i s i n f e c t i o n i s requi red, nea r l y a l l POTWs use ch lo r i ne as t h e d i s i n f e c t a n t and incorporate a c h l o r i n e contac t bas in o f s u f f i c i e n t s ize to prov ide 10 minutes t o 2 hours o f con tac t time.

I n b i o l o g i c a l wastewater t reatment f a c i l i t i e s t h a t p e r i o d i c a l l y l ose sludge so l i d s over the f i n a l c l a r i f i e r weirs, c h l o r i n e contac t basins general l y con ta in a bu i l dup o f sludge so l ids . I f more than 5-10 cm (2-4 i n ) o f sludge has b u i l t up on the bottom o f the basin, t h e r e i s a good chance t h a t s i g n i f i c a n t so l i d s l o s s i s occu r r i ng from the secondary c l a r i f i e r .

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3.3.2.6 Sludge Handling Capab i l i t y

The e v a l u a t o r ' s major concern w i t h sludge handling f a c i l i t i e s i s i n i d e n t i f y i n g any po ten t i a l "bot t lenecks" and p o s s i b l e a1 t e r n a t i v e s i f capac i ty problems a re ind ica ted . During t h e p l a n t t o u r , the eva lua to r should become f a m i l i a r w i t h the general f low pa t t e rn of sludge from the po in t a t w h i c h i t i s removed from the primary and secondary c l a r i f i e r s to the poin t of f i n a l disposal . All return flow streams should be identified d u r i n g the tou r and the p lan t personnel should be quest ioned regard ing each s t r e a m ' s volume and strength and the a v a i l a b i l i t y o f d a t a . Re tu rn superna tan t streams from anaerobic digesters a r e the most common return streams t h a t cause performance problems. Supernatant from aerob ic digesters and f i l t r a t e from dewatering ope ra t ions are gene ra l ly not a s e r ious problem.

3.3.2.7 Laboratory

The l abora to ry should be included a s p a r t of the p lan t tour. Performance monitor ing and process cont ro l t e s t i n g should be discussed w i t h l abo ra to ry personnel. Avai lable ana ly t i ca l c a p a b i l i t y should a1 so be determined. Sampling and ana ly t i ca l suppor t a r e o f t e n e s s e n t i a l p a r t s of the eva lua t ion e f f o r t and the eva lua to r should determine what level of suppor t i s a v a i l a b l e from the l abora to ry f o r the CPE.

3.3.3 Detailed Data Gathering

Following the p l a n t tour, a major e f f o r t i s i n i t i a t e d to c o l l e c t a l l da ta necessary t o assess the performance po ten t i a l of the existing f a c i l i t i e s . T h i s d a t a c o l l e c t i o n e f f o r t may require two o r three persons f o r 3-7 days i n a 1 a rge r p l a n t , and one o r two persons f o r 1-2 days i n a small er p l an t .

Information is c o l l e c t e d to document p a s t performance, process design , maintenance, management, budget, p rocess c o n t r o l , and admin i s t r a t ive pol icies. Co l l ec t ing information f o r many of these items requires the a s s i s t a n c e of POTw and o t h e r personnel. As such, the da ta ga the r ing should be scheduled around their a v a i l a b i l i t y . The time when key personnel a r e no t a v a i l a b l e should be used by the e v a l u a t o r to i n i t i a l l y review documents such a s O&M manuals and cons t ruc t ion p l ans , to summarize notes and ques t ions f o r POTW personnel , and t o check completeness o f d a t a c o l l e c t i o n .

The forms i n Appendix D have proven to be va luab le working guidelines f o r the d a t a c o l l e c t i o n e f f o r t (1-2). The items covered by these forms a r e l isted bel ow:

- General POTW Information, Fonn 0-1 - Adminis t ra t ive Data, Form D-2

2 4

- Design Data, Form D-3 - Operations Data, Form D-4 - Maintenance Data, Form D-5 - Performance Data, Form D-6

When c o l l e c t i n g data us ing these forms, t h e eva lua tor should be aware t h a t t h e data a re t o be used to evaluate the performance CaDab i l i t y o f the e x i s t i n g POTW. The eva lua tor should cont inuous ly be asking "HOW does t h i s a f f e c t p l a n t performance?" I f the area o f i n q u i r y i s d i r e c t l y r e l a t e d to p l a n t performance, such as a c l a r i f i e r design o r an a c h i n i s t r a t i v e p o l i c y t o c u t e l e c t r i c a l costs to an unreasonable l e v e l , the eva lua tor should spend s u f f i c i e n t t ime and e f f o r t t o f u l l y understand and de f ine the e f f e c t on p l a n t performance. If the area o f i n q u i r y i s n o t d i r e c t l y r e l a t e d to p l a n t performance, such as an opera to r ' s c e r t i f i c a t i o n o r the appearance o f t he p l a n t grounds, t he c o n d i t i o n should be noted and e f f o r t s d i r e c t e d toward areas t h a t s p e c i f i c a l l y impact performance.

Completion o f Form D - 1 requ i res t h a t values be se lected to represent c u r r e n t D l a n t hydrau l i c and organic loadings. Peak month loads should be used f o r these c a l c u l a t i o n s t o be compat ib le w i t h t h e d e f i n i t i o n o f secondary t reatment requirements used as the bas is f o r t h i s Handbook. In POTWs where special a1 l o w a k e has been made f o r h igh i n f i l t r a t i o n / i n f l o w , such as permi t ted bypassing above a selected f low, t h a t f l ow a t which secondary t reatment i s requ i red should be used.

3.4 Eva lua t i on o f Major U n i t Processes

Once data c o l l ec t ion has been subs tan t ia l l y completed, data eval ua t ion i s i n i t i a t e d . I n i t i a l focus i s on eva lua t ion o f the POTW's major u n i t processes t o determine t h e general a p p l i c a b i l i t y o f a CCP to improve Performance, i.e., d e f i n e the f a c i l i t y as Type 1, 2, o r 3 as descr ibed i n Chapter 2.

Performance cannot be improved to a des i red leve l unless e x i s t i n q ma,ior processes have adequate capaci ty to handle c u r r e n t loadings. The t h r e e bas ic un i t processes whose c,apaci t i e s most f requen t l y a f f e c t b i o l o g i c a l wastewater t reatment p l a n t performance are: a e r a t o r ( t he u n i t t h a t provides f o r t h e convers ion o f nonset t leab le organics) , the c l a r i f i e r ( s o l i d s / l i q u i d separator) , and the sludge hand1 i n g system (1-4).

A p o i n t system i s used t o quant i f y t h e eva lua t ion o f these th ree bas ic u n i t processes. Key l oad ing and process parameters a r e ca l cu la ted and r e s u l t s f o r each parameter assigned a score by comparison wi th standard tab les . Subsequently, each o f the th ree major u n i t processes receives a t o t a l score by adding together the p o i n t s assigned t h e l oad ing and process parameters. The t o t a l s a re then compared w i t h standards t o assess whether a Type 1, Type 2, o r Type 3 c a p a b i l i t y i s i n d i c a t e d f o r t h a t u n i t process. The o v e r a l l p l a n t type i s determined by the ''weakest l i n k " among the th ree major process areas. It must -be remembered i n us ing t h i s p o i n t system t h a t t h i s s i m p l i f i c a t i o n can prov ide Val uahle assi stance bu t cannot rep lace the o v e r a l l judgment and experience o f t h e evaluator.

25

3.4.1 Suspended Growth Major U n i t Processes

Suspended growth f a c i l i t i e s inc lude those p l a n t s using v a r i a t i o n s of the a c t i v a t e d s ludge process . The three s i g n i f i c a n t u n i t processes w i t h i n these types of f a c i l i t i e s t h a t determine capac i ty and performance a re the a e r a t i o n bas in , secondary c l a r i f i e r , and s ludge handling system.

3.4.1.1 Aeration Basin

Parameters t h a t a r e used f o r scor ing the c a p a b i l i t y o f an a e r a t i o n basin a re : hydraul i c de ten t ion time, organic 1 oading, and oxygen ava i l ab i l i ty . The po in t system f o r scor ing these parameters i s presented i n Table 3-2. To obta in the necessary parameters , information i s requi red on wastewater flow t o the a e r a t i o n bas in , a e r a t i o n basin BOD5 loading , a e r a t i o n basin l i q u i d volume, and oxygen t r a n s f e r capac i ty .

TABLE 3-2

PARAMETERS FOR SCORING CAPABILITY OF AERATION BASINS IN SUSPENDED GROWTH POTWs*

Current Operat i na Condit ion

Hydraul ic Detent ion Time, hr:

24 10

5 3

Organic Loading, kg BODg/mS/d (1 b/d/1,000 cu f t ) :

0.24 (15) 0.40 (25 ) 0.80 (50) 1.28 (80)

Oxygen A v a i l a b i l i t y , kg 02/kg BOD5 load:

2.5 1.5 1.2 1.0 0.8

Po in t s

10 (max. ) 6 0

-6

10 (max.) 6 0

-6

10 (max.) 5 0 -5

-10 ~ ~~~~~~~

* I n t e r p o l a t e t o nearest whole number between loadings 1 i s t e d .

26

Oxygen t r a n s f e r capac i ty i s usua l ly the most d i f f i c u l t information t o obta in i f the o r i g i n a l engineering da ta a r e not a v a i l a b l e o r i f there i s some reason t o ques t ion the o r i g i n a l design da ta based on c u r r e n t cond i t ions . General ly , the eva lua t ion proceeds by using a v a i l a b l e da t a on oxygen t r a n s f e r capac i ty and assuming i t is c o r r e c t unless the t r a n s f e r capac i ty appears t o be marginal. I f oxygen t r a n s f e r capac i ty appears marginal , further i n v e s t i g a t i o n i s warranted. Any of the fol lowing cond i t ions would lead an eva lua to r t o suspect marginal oxygen t r a n s f e r :

- Diff icul ty i n maintaining m i n i m u m D O

- Continuous opera t ion of a l l blowers, o r a l l a e r a t o r s set a t h i g h speed

- Design da ta showing less than 1.4 kg oxygen t r a n s f e r capac i ty per

I f design oxygen t r a n s f e r capac i ty i s unavai lab le o r i s believed suspect, oxygen t r a n s f e r r a t e s presented i n Table 3-3 can be used t o e s t ima te oxygen t r a n s f e r capaci t ies.

kg ac tua l BOD5 load

TABLE 3-3

TYPICAL STANDARD OXYGEN TRANSFER RATESa

Aerat ion System

Coarse bubble d i f f u s e d Fine bubb le diffuser$ Surface mechanical a e r a t o r s Submerged turbine a e r a t o r s d J e t ae ra to r se

Standard Oxygen Trans fe r Rate

l b 02/hp-hr

2.0 6.5 3.0 2.0 2.8

"Guidance f o r a d j u s t i n g t o f ie ld cond i t ions i s

bFor 2.7-3.6 m (9-12 f t ) submergence. cFor 18-26 w/m3 (0.7-1.0 hp-hr/ lOO cu f t ) . dInc ludes both blower and mixer horsepower. e Inc l udes both blower and pump horsepower.

presented i n Appendix F.

27

- Additional d a t a required to make the estimate are f ie ld measurements t o calculate wire horsepower and calculations t o adjust oxygen transfer rates from standard conditions to the local conditions of the subject plant. The oxygen transfer capacity ( k g / d ) i s equal t o the wire horsepower (from Appendix E ) times the actual oxygen transfer rate ( l b / h p - h r , from Appendix F ) times 24 h r / d times 0.454 k g / l b . When u s i n g Table 3-3 and Appendixes E and F, the evaluator shoul d remember that d a t a obtained through these estimating procedures are only approximate, b u t generally have the same degree of accuracy w i t h which oxygen demands can be predicted.

Once d a t a are available on wastewater flows, BOD5 of influent t o the aeration b a s i n , aeration basin volume, and oxygen transfer capacity, the f o l l owing cal cul ations shoul d be completed by the eval uator:

Aeration Basi n Vol ume verage Daily Wastewater Flow Hydraulic Detention Time i n Aerator = A

Oxygen Transfer Capacity = B O D 5 Loading Oxygen Avail abil i ty

When the above calculations have been completed for the subject POTW, the resu l t s are compared to the values given i n Table 3-2 and appropriate points are assigned each parameter. If the parameters for the subject POTW fa l l between the values l i s t e d , interpolation is used to assign appropriate points.

3.4.1.2 Secondary C1 ar i f i e r s

Parameters t ha t are used for scoring the capabili ty o f suspended growth secondary c l a r i f i e r s are: configuration, SOR, depth, return sludge removal mechanism, and return sludge control. The scoring system for these parameters is presented i n Table 3-4. The configuration score addresses the influence of the weir location on the r i s e ra te of the sludge blanket. A lower score is assigned when the effect ive c l a r i f i e r surface area i s judged t o be decreased due to the location o f eff luent weirs and launders. o r example, a c l a r i f i e r 15 m long and 3 m wide ( to ta l surface area of 45 $1 w i t h a $ wo-sided 1 - m wide weir located 1 m from the end is judged to have 9 of launder coverage [ ( 3 m wide) x (1 m + 1 m + 1 m ) ] , o r only 20% of the surface area. The parameter that needs to be determined to complete the c l a r i f i e r ' s evaluation i s SOR:

Flow from the C la r i f i e r 1 a n f i e r Surface Area SOR =

28

TABLE 3-4

PARAMETERS FOR SCORING CAPABILITY OF CLARIFIERS I N SUSPENDED GROWTH POTWs

Current ODerati na Condi t ion P o i n t s

Conf igurat ion:

C i r c u l a r w i t h "donut" o r i n t e r i o r 1 aunders 10 C i r c u l a r w i t h we i rs on w a l l s 7 Rectangular w i t h 33% covered w i t h 1 aunders 0 Rectangular w i t h 20% covered w i t h launders -5 Rectangular w i t h launder a t o r near end -10

Surface Overflow Rate, m 3 2 /m /d (gpd/sq f t ) :

12 (300) 20 (500) 27 (650) 33 (800) 41 (1,000) 49 (1,200)

Depth a t Weirs, m ( f t ) :

4.6 (15) 3.7 (12) 3.0 (10) 2.4 (8) 2.1 (7)

Return S1 udge Removal :

C i r c u l a r , r a p i d withdrawal C i r c u l a r , scraper to hopper Rectangul ar , cocurrent scraper Rectangular, countercurrent scraper No mechanical removal

15 10 5 0

-10 -1 5

10 4 0 -5

-1 0

10 8 2 0 -5

Return Ac t iva ted S1 udge Control :

Actual RAS f l o w range completely w i t h i n recommended RAS

Actual RAS f l o w range completely w i t h i n recanmended RAS

50% o f recommended RAS f l o w range covered by actual RAS

50% o f recommended RAS f l o w range covered by actual RAS

Actual RAS f l o w range completely ou ts ide recommended

f l o w range; c a p a b i l i t y t o meaSure RAS f l o w

f low range; no c a p a b i l i t y t o measure RAS f l o w

f l o w range; c a p a b i l i t y t o measure RA

f l o w range; no c a p a b i l i t y t o measure RAS f l o w

RAS f l o w range -5

10

7

5

0 ~

29

Evaluation of return activated sludge control i s based on the ab i l i t y t o control the return activated sludge f low ra te volume w i t h i n the range normally recommended f o r the particular type of activated sludge plant. Typical ranges for return activated sludge pumping ra tes are presented i n Table 3-5.

TABLE 3-5

TYPICAL RANGES FOR RETURN ACTIVATED SLUDGE PUMPING CAPACITIES

Process Type Return Activated S1 udge % of average daily wastewater flow

Conventional A.S. and ABF

Ex tended Aeration ( p l u g . flow o r complete m i x )

(including oxidation ditches) 50-100 Contact Stabil ization 50-125

25-75

3.4.1.3 S1 udge Hand1 i n g Capabil i t y

The capabili ty of s ludge handling f a c i l i t i e s associated w i t h an activated sludge plant i s scored by the cont ro l lab i l i ty of the wasting process and the capabil i t y o f the avail able sludge treatment and disposal f a c i l i t i e s . Scoring for sludge handling capabili ty i s not as straightforward as for the aerator or c l a r i f i e r . T h i s i s because the capacity of existing f a c i l i t i e s cannot be easi ly assessed due t o the var iab i l i ty t h a t ex is t s i n Precalculated "standards" f o r process or loading parameters. To evaluate the sludge hand1 ing capacity, the evaluator must f i r s t calculate expected s ludge production based on current loadings to the wastewater treatment processes. The evaluator then assesses the capabili ty o f the existing sludge f a c i l i t i e s t o handle the calculated s ludge production.

The c r i t e r i a and point system f o r evaluating sludge handling capabili ty a re presented i n Table 3-6. As indicated by the lower p o i n t s al located, cont ro l lab i l i ty i s much less important than capacity.

30

TABLE 3-6

CRITERIA FOR S C O R I N G SLUDGE HANDLING CAPABILITY FOR SUSPENDED GROWTH POTWs

Current Operat ing Condit ion

C o n t r o l l a b i l i t y :

Automated sampl i n g and volume con t ro l Metered volume and hand sampling Hand measured vol ume and hand sampl i ng Sampl i n g o r volume measurement by hand not p rac t i ca l

Capaci ty:

150% of ca l cul a ted long-term average sl udge product ion 125% of c a l c u l a t e d long-term average sludge production 100% of cal cul a ted long-term average sl udge product ion

75% o f c a l c u l a t e d long-term average sludge production 50% of ca l cul a t ed long-term average sl udge product ion

P o i n t s

25 20 15 0

-1 0

C o n t r o l l a b i l i t y of the wasting process i s ind ica t ed by the type o f waste sludge volume measurement and the type of waste sludge sampling a v a i l a b l e . The optimum cont ro l f o r an ac t iva t ed s ludge wast ing system inc ludes automatic volume cont ro l and automatic sampling. A p o s i t i v e displacement pump and automatic sampler, both con t ro l l ed by an accura te and precise c lock , i s an example of t h i s type o f c o n t r o l .

Most small a c t i v a t e d sludge plants can manually measure a wasted volume ( r i s e i n holding tank o r digester, o r the number of tank trucks f i l l ed ) and manually sample (from a t a p o r the open end of the waste sludge l ine) . Most l a r g e r p l a n t s have flow measuring and t o t a l i n g devices on waste sludge lines.

Capaci ty of existing sludge handling f a c i l i t i e s i s evaluated using the fol lowing procedures:

I I - Calcu la t e expected sl udge product ion. I

- Establ i sh capaci t y of exi s t i n g sl udge hand1 i ng u n i t processes.

- Determine percentage of the c a l c u l a t e d sludge production each u n i t p rocess can handle.

- Ident i fy the "weakest l i n k " p rocess a s the ove ra l l capac i ty of the - existing sludge handling f a c i l i t i e s and compare to scor ing va lues

i n Table 3-6.

31

Expected sludge product ion i s ca lcu la ted us ing cur ren t BOD5 loadings (un less bel ieved inaccurate) and t y p i c a l u n i t sludge product ion V a l ues f o r t h e e x i s t i n g wastewater t reatment processes ( 5 ) . Typical u n i t sludge product ion values f o r var ious processes are shown i n Table 3-7. For example, an o x i d a t i o n d i t c h removing about 1,000 kg BOD /d would be expected t o have an

TSS/kg BOD5 removed). average sludge product ion of about 650 kg T ‘5 S/d (1,000 kg BOD5/d x 0.65 kg

TABLE 3-7

TYPICAL UNIT SLUDGE PRODUCTION VALUES FOR SUSPENDED GROWTH POTWs

Process Type

Primary C1 a r i f i c a t i o n 1.7

k g TSS (s ludge) /kg BOD5 removed

a Act iva ted S1 udge w/Primary C1 a r i f i c a t i o n 0.7

Act ivated S1 ud e w/o Primary C l a r i f i c a t i o n Conventional i 0.85 Ex tended Aera t ionb 0.65 Contact S t a b i l i z a t i o n 1.0

aIncludes tapered aerat ion, step feed, p l u g f low, and

b I n c l udes o x i d a t i o n d i t c h . complete mix w i t h wastewater de ten t ion times < l o hours.

I f p l a n t records inc lude sludge product ion data, t h e actual u n i t sludge product ion value should be compared t o the t y p i c a l value. If a discrepancy greater than 15 percent e x i s t s between these values, f u r t h e r evaluat ion i s warranted. The most common causes o f inaccurate recorded sludge product ion are:

- Excessive s o l i d s l o s s over t h e f i n a l c l a r i f i e r we i rs - Inaccurate waste volume measurement - I n s u f f i c i e n t waste sampling and concentrat ion analyses - Inaccurate determinat ion o f BOD removed

Using the determined u n i t sludge product ion values and actual BOD5 removals for the subject p l a n t , t h e expected mass o f sludge produced per day can be ca lcu lated. To complete the scor ing o f sludge handl ing c a p a b i l i t y , the expected volume o f sludge produced per day should a lso be ca lcu lated.

32

Typical waste sludge concent ra t ions f o r ac t iva t ed s ludge p l a n t s a r e presented i n Table 3-8 and can be used t o conver t the expected mass of sludge produced per day t o the expected volume of s ludge produced per day.

TABLE 3-8

TYPICAL SLUDGE CONCENTRATIONS FOR SUSPENDED GROWTH POTWs

Sludge Type Waste Concentrat ion mg/l

P r i mary 50,000

Act i va ted Return S1 udge/Co nventional 6,000 Return S1 udge/Extended Aeration 7,500 Return S1 udge/Contact S t ab i l i z a t i o n 8,000

Separa te waste hopper i n secondary c la r i f ie r 12,000 a Return S1 udge/smal 1 p l a n t w i t h low SOR* 10,000

Returns can often be s h u t o f f for s h o r t per iods to h i ken waste sludge i n c l a r i f i e r s w i t h SORs less than 20 $/m5/d (500 gpd/sq f t ) .

*

The c a p a c i t y of each of the components of the sludge handling process must be eva lua ted w i t h respect to i t s a b i l i t y t o handle the ca l cu la t ed long-term average sludge production for c u r r e n t loadings. Any process t h a t may become a "bot t leneck" shoul d be considered c r i t i c a l . Typical components found i n a c t i v a t e d sludge fac i l i t i es a r e : t h i cken ing , d i g e s t i o n , dewatering, haul ing , and d isposa l .

Guidel ines for the capac i ty evaluation of the components o f the e x i s t i n g sl udge handl i ng processes are provided i n Tables 3-9 and 3-10. The guide1 ines provided i n Table 3-9 are used to compare e x i s t i n g f a c i l i t y capac i ty t o expected sludge oduction. For example, an e x i s t i n g ae rob ic d i g e s t e r w i t h a volume of 380 my (100,000 gal 1 i n a p l a n t w i t h a c a l c u l a t e d waste s ludge volume of 19 $/d (5,000 ga l /d ) would have a hydraul ic de ten t ion time of 20 days. This is 133 percent of the gu ide l ines provided for aerobic d i g e s t e r s i n Table 3-9. T h u s , th is component of the s ludge handling process i n this p a r t i c u l a r POTW would have capac i ty f o r 133 percent of the long-term average sludge production. I f the aerobic d i g e s t e r proved to have the lowest capac i ty t o handle long-term average s ludge product ion of a l l the components of the sl udge handl i n g processes i n this POTW, s ludge handl ing c a p a b i l i t y would score 22 p o i n t s ( i n t e r p o l a t e d from Table 3-6) . The s ludge handling c a p a b i l i t y eva lua t ion i s i l l u s t r a t e d as par t of the C P E example presented i n Sec t ion 3.9.

33

TABLE 3-9

GUIDELINES FOR EVALUATING CAPACITY OF E X I S T I N G SLUDGE HANDLING PROCESSES

Process

Grav i ty Thickeners P r i m a r y S1 udge Ac t iva ted S1 udge Pr imary + Ac t iva ted F ixed F i l m Pr imary + F ixed F i lm

D i ssolved A i r F1 o t a t i o n Primary S1 udge q c t i v a t e d S1 udge Primary + Ac t iva ted F ixed F i l m Primary + F ixed F i l m

Digesters Aerobic Anaerobic

S ing le Stage Two Stage

Drying Beds

Mechanical Dewatering S ing le U n i t Mu1 ti p l e Uni t s

L i q u i d S1 udge Haul Short Haul ( < 3 km) Long Haul (>20 km)

Parameters That Can Be Used t o Represent 100% o f Required

S1 udge Hand1 i n g Capaci tya - 125 kg/m2/d ( 2 5 lb /d /sq ft) 20 k g / d / d ( 4 l b /d /sq f t ) 50 kg/m2/d (10 lb /d /sq f t ) 40 kg/t$/d (8 l b / d / s q ft) 75 kg/m2/d (15 lb /d /sq f t )

15 days' hydrau l i c de ten t ion timeb

40 days ' hydraul i c de ten t ion t ime 30 days' combined hydraul i c detent ion t ime

Worst season turnover t ime

30 hours o f operation/week 60 hours o f operation/week ( w i t h one u n i t

out o f serv ice)

6 t r ips /day maximum 4 t r i p s / d a y maximum

aCapacity o f e x i s t i n g u n i t processes should n o t be downgraded t o these values i f good operat ion and process performance are documented a t h igher loadings. a1 1 sludge product ion has been successful ly thickened i n a g r a v i t y a c t i v a t d sludge th ickener f o r t h e past year a t an average load ing of

--to have 100% o f requ i red capaci ty. bHydraul i c de ten t ion t ime = Vol ume of d igester /Vol ume o f waste sludge

expected t o be produced.

For example, i f records appear accurate and show t h a t

25 kg/m f / d ( 5 l b / d / s q ft), the e x i s t i n g th ickener should be considered

34

TABLE 3-10

MISCELLANEOUS UNIT VALUES USED I N EVALUATING C A P A C I T Y OF SLUDGE HANDLING CAPABILITYa

Aerobic Digesters Fol 1 owing Extended Aerat ion (MCRT>20 days)

Aerobic Digesters Fol 1 owing Conventional A. S. (MCRTc12 days)

Anaerobic D i gesters f o r A c t i v i t e d + Primary, and F ixed F i l m (Supernat ing Capabil i t y Useabl e)

Digesterb HDT days

10 15 20

>3 0

10 15

>2 0

20 30 40

V o l a t i l e Sol i d s Content o f Waste Ac t iva ted S1 udge,

Convention a 1 ( MCRT 4 2 days ) Extended Aerat ion (MCRT>20 days)

Total Sol ids Output Sol ids Reduction Concentrat ion

% mg/l

10 12,000

35 20 , 000

20 15,000 30 17,000

20 35 40

12,000 15,000 17 , 000

25 Equal t o i n p u t 35 10% greater than i n p u t 45 20% greater than i n p u t

80% 70 %

aValues i n t a b l e are intended f o r use i n a l l o w i n g an eva lua t ion o f sludge handl ing c a p a b i l i t y t o proceed i n the absence o f a v a i l a b l e p l a n t data. o ther v a r i a b l e s can a f f e c t t h e values of t h e parameters shown.

bHydraul ic de ten t ion t ime = Volume o f digester/Volume o f waste sludge expected t o be produced.

Many

3.4.1.4 Suspended Growth Major U n i t Process Anal y s i s

Once i n d i v i d u a l major u n i t processes are evaluated and given a score, these r e s u l t s should be recorded on a summary sheet, as shown i n Table 3-11, and compared w i t h standards f o r each major u n i t process and the t o t a l p lan t . This ana lys is r e s u l t s i n the subject POTW being ra ted a Type 1, Type 2, o r Type 3 f a c i l i t y , as described i n Chapter 2. The sum o f the p o i n t s scored f o r a e r a t i o n basin, secondary c l a r i f i e r , and sludge handl ing c a p a b i l i t y must be 60 o r above f o r the subject POTW t o be designated a Type 1 f a c i l i t y . Furthermore, regard less of t o t a l po in ts , t h e aera tor must score a t l e a s t 13 points , t h e secondary c l a r i f i e r a t l e a s t 25 po in ts , and sludge handl ing c a p a b i l i t y a t l e a s t 10 p o i n t s f o r the p l a n t t o be considered Type 1.

35

TABLE 3-11

SUSPENDED GROWTH MAJOR UNIT PROCESS CAPACITY EVALUATION

P o i n t s Required* P o i n t s Scored Type 1 Type 2 T W

Aera t ion Basin 13-30 0-1 2 4 Secondary C1 ari f i e r 25-55 0-24 <O S1 udge Handl ing Capabil i t y 10-30 0- 9 4

Total 60-115 20-59 <2 0

Each u n i t process a s well as the overall t o t a l po in t s must f a l l i n the designated range f o r the p l an t to achieve the Type 1 o r Type 2 r a t i n g .

*

I f the s u b j e c t POTW meets the cr i ter ia f o r a Type 1 p l a n t , the eva lua t ion has ind ica t ed t h a t a l l major processes have adequate capac i ty for a CCP t o be ab le t o br ing the p l a n t i n t o compliance. If the total i s less t h a n 60 p o i n t s , or i f any one major u n i t process scores less t h a n i t s m i n i m u m , the f a c i l i t i e s must be designated as Type 2 or Type 3.

The m i n i m u m c r i t e r i a f o r a Type 2 p l a n t a r e 20 t o t a l p o i n t s and z e r o f o r each ind iv idua l process. I f the to t a l i s less t h a n 20, or i f any major process scores a nega t ive value, the POTW must be considered inadequate and the p l a n t designated as Type 3. Type 3 p lan ts gene ra l ly r e q u i r e major cons t ruc t ion before they can be expected t o meet secondary treatment e f f l u e n t limits.

A suspended growth POTW t h a t scored the fol lowing during the eva lua t ion of major u n i t processes would meet the cr i ter ia f o r a Type 3 p l a n t :

Aeration Basin 14 p o i n t s Secondary C1 a r i f i e r -8 p o i n t s

10 p o i n t s S1 udge Handl i ng Capabil i t y

Total 16 poin ts -

The p o i n t system i n Table 3-11 has been developed to a i d i n a s ses s ing the c a p a b i l i t y of a POTW's major physical fac i l i t i es . I t cannot replace the overall judgment and experience of the evaluator, w h i c h i s often the deciding factor i n determining the a p p l i c a b i l i t y of a CCP.

36

3.4.2 F i xed F i l m Major U n i t Processes

F ixed f i l m f a c i l i t i e s inc lude those p l a n t s us ing rock o r p l a s t i c media p l u s those us ing the RBC o r ABF v a r i a t i o n s o f the bas ic . t r i c k l i n g f i l t e r process. The u n i t process i n f i x e d f i l m wastewater t reatment p l a n t s t h a t most s i g n i f i c a n t l y a f f e c t s capac i ty and performance i s the "aera tor " p o r t i o n of the p lan t , i.e., the amount and type o f t r i c k l i n g f i l t e r media, RBC media, e tc . Other s i g n i f i c a n t u n i t processes are the secondary c l a r i f i e r and sludge hand1 i ng capabi 1 i ty .

3.4.2.1 Aera tor

a. T r ick1 i n g F i l t e r s

An approach t o develop ' 'equivalency" i s used to evaluate the capac i ty o f t r i c k l i n g f i l t e r s o f vary ing y d i f types. The u n i t surface area fo r common rock mkdia i s t y p i c a l l y 43 m /m (13 sq f t / c u f t ) (6 ) . This i n fo rma t ion can be used t o conver t data from t r i c k 1 i n g f i l t e r s w i t h a r t i f i c i 1 media t o equ iva len t volumes o f common rock media. For example, 1,000 $ $3,500 cu f t ) o f a p l a s t i c media w i t h a s p e c i f i c su r fa e area o f 8 8 /m (27 sq

(7,300 cu f t ) o f common rock media. U n i t surface area in format ion f o r var ious media types i s genera l l y a v a i l ab le i n manufacturers ' 1 i t e r a t u r e .

f t / c u f t ) i s equ iva len t to (89/43) x (1,000 m 5 ) o r 2,070 m

Using the equivalency c a l c u l a t i o n , organic load ings can be ca l cu la ted f o r a1 1 types o f media. Despite f i x e d f i l m performance being a f u n c t i o n o f sur face area, load ings f o r t r i c k l i n g f i l t e r s a re t y p i c a l l y expressed as mass o f BOD5 per volume o f media. The vo lumetr ic l oad ing can be ca l cu la ted us ing t h e equiva l ency c a l c u l a t i o n presented above. Resul t s can be compared w i t h c r i t e r i a i n Table 3-12 t o compute a "score" f o r the t r i c k l i n g f i l t e r .

The capac i t y o f a t r i c k l i n g f i l t e r can be s i g n i f i c a n t l y decreased i f t h e media becomes plugged. Ponding on the f i l t e r i s a common i n d i c a t o r o f p lugging and i s genera l l y due t o overgrowth o f microorganism mass o r d i s i n t e g r a t i o n o f t h e media. The eva lua tor should inspec t the f i l t e r i n several p laces by removing media t o a depth o f a t l e a s t 15 cm (6 i n ) t o ensure t h a t pondinq o r p lugging underneath the upper l a y e r o f rocks i s n o t occur ing.

b. RBCs

Parameters f o r scor ing RBCs a re presented i n Table 3-13 (7 ) . The key parameters t o be evaluated are: o rgan ic l oad ing on t h e f i r s t stage and on the e n t i r e system; number o f stages provided; and whether o r no t sidestreams from anaerobic- sludge treatment are received. Organic l oad ing used f o r eva lua t i ng RBCs i s so lub le BOD5 (SBOD5) per u n i t o f media. If data are no t ava i lab le , SBOD5 i s est imated f o r t y p i c a l domestic wastewater as one-hal f

37

TABLE 3-12

PARAMETERS FOR SCORING AERATOR CAPABILITY FOR TRICKLING FILTER POTWs

Current Operating Condition

Organic Loading, kg BODs/m3/d (lb/d/1,000 cu f t ) : a

0.16 (10) 0.32 (20) 0.48 (30) 0.80 (50) 1.12 (70)

Recirculation, r a t i o to raw flow:

2: 1 1: 1 No ne

Points Covered t-il t e r

Freezing o r Nonfreeti ng Tempera t u res Tempera t u resb

20 15 20 0 10

-10 -5 -20 -1 0

3 2 0

Anaerobic Si destreams:c

Not returned ahead of the t r ickl ing f i l t e r 0 Returned to the wastewater stream ahead of the t r ick l ing f i l t e r -1 0

aBased on primary e f f luent nd common rock media having a spec i f ic

bTemperatures below freezing f o r more than one month. CSupernatant from anaerobic digesters o r f i l trate/concentrate from

surface area of about 43 &/m3 (13 sq f t /cu f t ) .

the dewatering processes following anaerobic digesters.

the primary e f f luent total BODg. If s ignif icant industrial contributions are present i n the system, SBOD5 should be determined by testing.

Surface area data f o r RBCs are generally available i n manufacturers' l i t e r a t u r e or i n plant O&M manuals. If these sources a re unavailable o r do not contain the needed information, the manufacturer's representative or the manufacturer should be contacted to obtain the data.

First-stage media loading i s calculated by d i v i d i n g the mass of SBOD5 going to i t by the total surface area of only the f i r s t - s tage media. System media loading is calculated by dividing the total SBOD5 load to the RBCs by the total surface area of a l l RBC media. In most cases, the mass of SBOD5 will be the same for these calculations. They should only be different i n plants where some of the SBOD5 load i s bypassed around the f i r s t stage.

30

TABLE 3-13

PARAMETERS FOR SCORING AERATOR CAPABILITY FOR RBC POTWsa ( 7 )

Current Operat ing Condi t ion P o i n t s

F i rs t -S tage Loading, g SBODg/d/d (1 b/d/1,000 sq f t ) :

12 (2.5) 20 (4.0) 29 (6.0)

System Loading, g SBOD5/d/d ( lb/d/1,000 sq f t ) :

2.9 (0.6) 4.9 (1.0) 7.3 (1.5)

Number o f Stages:

4 3 2

Anaerobic Sidestreams:b

Not re turned ahead o f RBC Returned t o wastewater stream

ahead o f RBC

10 0

-6

10 0

-6

10 7 4

0

-1 0

aInc ludes mechanical and a i r d r i v e RBCs. bsupernatant from anaerobic d iges ters o r f i l t r a t e / c o w e n t r a t e

from the dewatering processes f o l l owing anaerobic d igesters .

c. ABFs

Parameters f o r evaluat ing ABF aera tors a re presented i n Table 3-14 (8). The key parameters are: b i o c e l l organic load ing and a e r a t i o n bas in de ten t ion time. A c r i t e r i o n o f 1 esser importance i s r e c i r c u l a t i o n d i r e c t l y around the b i o c e l l . Organic loadings on the b i o c e l l are c a l c u l a t e d i n a manner s i m i l a r to t r i c k l i n g f i l t e r loadings: pr imary e f f l u e n t BOD5 i s d i v i d e d by t h e volume o f the b i o c e l l media. Aerat ion bas in de ten t ion t ime i s c a l c u l a t e d i n a manner s i m i l ar to a c t i v a t e d sludge aera t ion basin hydraul i c de ten t ion t ime: t h e a e r a t i o n basin l i q u i d volume i s d i v i d e d by the average d a i l y wastewater f low. Sludge r e c i r c u l a t i o n i s n o t inc luded i n t h e c a l c u l a t i o n .

39

TABLE 3-14

PARAMETERS FOR SCORING AERATOR C A P A B I L I T Y FOR ABF POTWs (8 )

Current Operat ing Condi t ion Po in ts

B i o c e l l Organic Loading, kg BOD5/m3/d (1 b/d/1,000 cu f t ) :

1.6 (100) 2.4 (150) 2.8 (175) 3.2 (200) 4.0 (250) 4.8 (300)

15 10

5 0

-5 , l o

Aera t ion Basin Detent ion Time, hours:

4 20 3 15 2 1 2 1 5 0.75 0 0.5 -1 0

Oxygen A v a i l a b i l i t y i n Aerat ion Basin, kg 02/kg BOD5 t o B i o c e l l :

1.0 0.75 0.5 0.4 0.3

R e c i r c u l a t i o n - D i r e c t l y Around B i o c e l l , r a t i o t o raw f low:

1: 1 No ne

10 7 3 0

-1 5

3 0

Oxygen a v a i l a b i l i t y i n t h e aera t ion bas in o f an ABF p l a n t i s c a l c u l a t e d by d i v i d i n g mass o f oxygen t r a n s f e r capac i ty by the t o t a l mass o f BOD5 app l ied t o t h e b i o c e l l . This i s done because t h e removal a t t r i b u t e d t o t h e b i o c e l l versus t h a t occur r ing i n the a e r a t i o n bas in i s n o t e a s i l y d is t ingu ished. Most ABF p l a n t s prov ide f o r r e c i r c u l a t i o n d i r e c t l y around t h e b i o c e l l . R e c i r c u l a t i o n i s c a l c u l a t e d as a r a t i o t o raw f low.

40

3.4.2.2 Secondary C1 a r i f i e r

C r i t e r i a f o r scor ing t h e c a p a b i l i t y o f secondary c l a r i f i e r s i n t r i c k 1 i n q f i l t e r and RBC p l a n t s a r e presented i n Table 3-15. The c a l c u l a t i o n s r e q u i r e t h a t wastewater f l o w r a t e and t h e c l a r i f i e r c o n f i g u r a t i o n , surface area, and depth be known (see Sect ion 3.4.1.2). For ABF p lants , t h e c r i t e r i a f o r suspended growth secondary c l a r i f i e r s presented i n Table 3-4 are more appropr ia te and shoul d be used.

TABLE 3-15

PARAMETERS FOR SCORING CAPABILITY OF*CLARIF IERS I N TRICKLING FILTERS AND RBCs

I Current Ooerat i nq Cond i t ion

Conf igura t ion :

C i r c u l a r w i t h "donut" o r i n t e r i o r launders C i r c u l a r w i t h wei rs on w a l l s Rectangul a r w i t h 33% covered w i t h 1 aunders Rectangul a r w i t h 20% covered w i t h launders Rectangul a r w i t h 1 aunder a t o r near end

Surface Overf low Rate, m3/$/d (gpd/sq f t ) :

12 (300) 20 (500) 27 (650) 33 (800) 41 (1,000) 49 (1,200)

Depth a t Weirs, m ( f t ) :

3.7 (12) 3.0 (10) 2.1 (7)

P o i n t s

10 7 0 -5

-1 0

15 10 5 0

-1 0 -1 5

5 3 0

F o r ABF p lan ts , c r i t e r i a f o r suspended growth c l a r i f i e r s (Table 3-4) should be used.

*

41

3.4.2.3 S1 udge Hand1 ing Capabil i t y

C r i t e r i a f o r scor ing sludge handl ing c a p a b i l i t y a s s o c i a t e d w i t h f i xed f i lm p l a n t s a r e presented i n Table 3-16. The c r i t e r i a f o r c o n t r o l l a b i l i t y i n Table 3-16 a re se l f -explana tory . The capac i ty of sl udge handl ing a s s o c i a t e d w i t h f i x e d f i l m i s eva lua ted using the same four -s tep approach presented i n Sec t ion 3.4.1.3 f o r suspended growth POTWs.

TABLE 3-16

CRITERIA FOR SCORING SLUDGE HANDLING CAPABILITY FOR FIXED FILM POTWs

Current ODeratina Condit ion

Control l a b i l i ty :

Automated sampl i ng and vol ume cont ro l Metered vol ume and hand sampl i ng Hand measured volume and hand sampling Sampl ing or vol ume measurement by hand not practical

Capaci t y :

125% of c a l c u l a t e d 1 ong- term average sl udge production 100% of c a l c u l a t e d long-term average s ludge product ion

75% of c a l c u l a t e d long-term average sludge product ion 50% of c a l c u l a t e d long-term average sl udge oroduct ion

Points

25 15 5

-1 0

D i f f e r e n t u n i t s ludge product ion Val ues a re used i n determining expected sludge production from f ixed f i l m f a c i l i t i e s . A summary of t yp ica l u n i t s ludge product ion values f o r the va r ious types o f f ixed f i l m p l a n t s i s presented i n Table 3-17.

Frequent ly , secondary sludge from f ixed f i lm fac i l i t i es i s re turned to the primary clarifiers. Typical underflow concen t r a t ions o f the combined sl udqe from the primary c l a r i f i e r are shown i n Table 3-17 a s well as s ludge concen t r a t ions from the individual f i x e d f i l m processes.

The g u i d e l i n e s presented i n Tables 3-9 and 3-10 can be used to h e l p an eva lua to r determine the capac i ty 1 imits of e x i s t i n g sl udge treatment and d isposa l f a c i l i ties.

42

TABLE 3-17

TYPICAL UN IT SLUDGE PRODUCTION VALUES AND SLUDGE CONCENTRATIONS FOR FIXED FILM POTWs

Process TVDe

Primary C1 ari f i c a t i o n

Trickl ing Fi l ter RB C ABF

Sludge Type

Primary Primary + Trickl ing F i l te r Primary + RBC Primary + ABF t r i c k 1 ing F i l t e r RB C ABF

kg TSS (s ludge) /kg BOD5 removed

1.7

1.0 1.0 1.0

Waste Concentrati on, mq/l

50,000 45,000 45,000

30,000 30,000

35,000

12,000

3.4.2.4 Fixed F i l m Major U n i t Process Analysis

Once major f ixed f i l m processes are eva lua ted , t hey should be summarized and compared to s tandards f o r each type o f f ixed f i lm f a c i l i t y . Tables 3-18, 3-19, and 3-20 can be used f o r this purpose.

The s t anda rds are arranged similar t o those f o r suspended growth f a c i l i t i e s presented i n Table 3-11 and d iscussed i n Sec t ion 3.4.1.4. T h i s a n a l y s i s results i n the s u b j e c t POTW being r a t ed Type 1, Type 2, or Tvpe 3 , as descr ibed i n Chapter 2. Using these t a b l e s , the s u b j e c t p l a n t mus t score the m i n i m u m number of p o i n t s l i s t e d f o r each indiv idua l process and t h e m i n i m u m number t o t a l p o i n t s f o r a l l processes f o r the p l a n t t o q u a l i f y for a s p e c i f i c p l a n t type. For example, a t r i c k l i n g f i l ter p l a n t scor ing the fol lowing would meet the cr i ter ia f o r a Type 1 f a c i l i t y f o r ove ra l l po in ts , aerator, and secondary c la r i f ie r , bu t would be c l a s s i f i e d Type 2 because of i t s s c o r e for sl udge hand1 i ng capabi 1 i t y .

Trickl ing Fil ter 21 po in t s Secondary C1 a r i f i er 27 p o i n t s S1 udge Hand1 i ng Capabi 1 i t y - 6 p o i n t s

Total 54 points

43

TABLE 3-18

TRICKLING FILTER MAJOR UNIT PROCESS CAPACITY EVALUATION

Po in ts Required* Type 1 1 Y 7 m Po in ts Scored

'I Aera t o r'l 17-23 0-1 1 <O Secondary C1 a r i f i e r 17-30 0-16 <O S1 udge Handl i n g Capabil i t y 10-3 0 0- 9 <o

To t a l 45-83 15-44 <15

TABLE 3-19

RBC MAJOR W I T PROCESS CAPACITY EVALUATION

Po in ts Required* Po in ts Scored Type 1 Type 2 Type 3

I' Ae r a t o r I' 14-30 0-13 <O Secondary C1 a r i f i e r 17-30 0-1 6 <O S1 udge Handl i ng Capabi 1 i ty 10-30 0- 9 <O

Tota l 48-90 15 -47 <15

TABLE 3-20

ABF MAJOR UNIT PROCESS CAPACITY EVALUATION

Po in ts Requi red* Po in ts Scored Type 1 Type 2 -7 j 6n

"Aerator" 15-48 0-1 4 <O Secondary C1 a r i f i e r 20-55 0-19 <O S1 udge Handl i n g Capabil i ty 10-30 0- 9 <O

To ta l <15 50-133 15-49

Each u n i t process as we l l as t h e ove ra l l t o t a l p o i n t s must f a l l i n t h e designated range f o r the p l a n t t o achieve the Type 1 o r TyDe 2 ra t i ng .

*

44

3.5 Eva1 u a t i o n o f Performance-Limi t i n g Factors

The i d e n t i f i c a t i o n o f performance-l imi t i n g fac to rs should be completed a t a l o c a t i o n other than the POTW so t h a t a l l p o t e n t i a l f a c t o r s can be discussed o b j e c t i v e l y . The check1 i s t o f performance-1 i m i t i n g f a c t o r s presented i n Appendix A, as we l l as the gu ide l ines f o r i n t e r p r e t i n g these fac to rs , p rov ide the s t r u c t u r e f o r an organized rev iew o f problems i n t h e sub jec t POTW. The i n t e n t i s t o i d e n t i f y as c l e a r l y as poss ib le the f a c t o r s t h a t most accurate ly descr ibe t h e causes o f 1 i m i ted performance. For example, poor a c t i v a t e d sludge operat ion may be causing poor p l a n t performance because the operator i s improper ly apply ing a c t i v a t e d sludge concepts. I f t h e operator i s s o l e l y responsib le f o r process c o n t r o l dec is ions as we l l as f o r t e s t i n g f o r these decis ions, the f a c t o r o f improper a p p l i c a t i o n o f concepts should be i d e n t i f i ed.

Often, operator i n a b i l i t y can be t raced to another source, such as an O&M manual con ta in ing inaccurate in fo rmat ion o r a technica l consu l tan t who provides r o u t i n e assistance to the operator. I n t h i s case, improper a p p l i c a t i o n o f concepts p l u s t h e source o f t h e problem (O&M manual o r improper technica l guidance) should be i d e n t i f i e d as per formance- l imi t ing fac to rs , since b o t h must be cor rec ted i n a CCP to achieve des i red p l a n t performance.

Whereas t h e c h e c k l i s t and gu ide l ines i n Appendix A prov ide t h e s t r u c t u r e f o r t h e i d e n t i f i c a t i o n of. performance-l imi t i n g f a c t o r s , notes taken dur ing the p l a n t tour and d e t a i l e d data-gather ing a c t i v i t i e s ( i n c l u d i n g t h e completed forms from Appendix D ) prov ide the technica l resources f o r i d e n t i f y i n g these fac to rs .

Each f a c t o r i d e n t i f i e d as l i m i t i n g performance should be weighed w i t h respect t o impact on p l a n t performance and assigned an "A," "6," o r "C" r a t i n g as discussed i n Sect ion 2.2.3. Fur ther p r i o r i t i z a t i o n i s accomplished by completing the summary sheet presented i n Appendix 6. General ly, o n l y those f a c t o r s r e c e i v i n g e i t h e r an ''A" o r "B" r a t i n g are p r i o r i t i z e d on t h i s sheet.

Add i t iona l guidance f o r i d e n t i f y i n g and p r i o r i t i z i n g performance-1 i m i t i n g f a c t o r s i s provided i n the f o l l o w i n g sect ions f o r the general areas o f admin is t ra t ion , design, operat ion, and maintenance.

3.5.1 Admini s t r a t i o n Factors

The budget i s t h e mechanism whereby POTW owners/administrators genera l l y implement t h e i r ob ject ives. Therefo're, eval u a t i o n and d iscuss ion o f the budget i s an e f f e c t i v e mechanism f o r i d e n t i f y i n g a d m i n i s t r a t i v e performance-1 i m i t i n g f a c t o r s . For t h i s reason, e a r l y dur ing the o n s i t e f ie ldwork t h e evaluator should schedule a meeting w i t h t h e key POTW decisionmaker and the "budget person." Th is meeting should be scheduled to occur a f t e r t h e evaluator i s t e c h n i c a l l y f a m i l i a r w i t h t h e p lan t .

45

Nearly every POTW budget i s set up differently so i t helps t o review the budge t w i t h the assistance of p l a n t personnel t o real i stical l y rearrange the budge t l i n e items i n t o categories emphasizing various costs. Forms for col lect ing budget d a t a are presented i n Appendix D. Analysis of these d a t a can be supported by comparison w i t h typical values for wastewater treatment plants (1)(4)(9)(10). POTWs larger t h a n 8,000 m3/d (2 mgd) i n size usually have budgets t h a t clearly describe wastewater treatment costs. Budgets for smaller POTWs are often combined w i t h budgets for other u t i l i t i es , such as wastewater collection, water treatment and distribution, or even street repairs and maintenance. For this reason, i t i s often more d i f f i c u l t and time consuming t o establ ish real i s t ic costs for small POTWs.

Key POTW administrators should be ident i f ied and interviews scheduled w i t h t h e m as described i n Section 3.2.1. As a general rule, the POTW operating staff should not attend the interviews w i t h POTW administrators because their presence may i n h i b i t open discussion.

The evaluation of a b i n i strative performance-1 imi t i n g factors i s by nature subjective. Typ-ically, a l l administrators verbally support goals o f low costs, safe working condi t ions , good treatment performance, h i g h employee morale, etc. An important question t h a t the evaluator must ask i s , "Where does good treatment f i t i n ? " Often this question can be answered by observing the priority of items implemented or supported by administrators. The ideal situation i s one i n w h i c h the abinistrators func t ion w i t h fu l l awareness t h a t they w a n t t o achieve desired performance as an end product of their wastewater treatment efforts. Improving working conditions, lowering possible costs, and other similar goals would be pursued w i t h i n the realm of f i r s t achievinq adequate performance.

A t the other end of the spectrum i s an administrative attitude t h a t ''we just raised the monthly rates 100 percent las t year; we aren't spending another dime on t h a t p l an t . " POTW administration can be judged by the following cri teria:

Excel 1 ent: Re1 i ab ly provides adequate wastewater treatment a t

Normal : Provides best possible treatment w i t h the money

1 owest reasonable cost.

avail ab1 e.

Poor: Spends as l i t t l e as possible w i t h no correlation made to achieving adequate p l a n t performance.

Administrators who f a l l i n t o the ''poor'' category t y p i c a l l y are identified as c o n t r i b u t i n g to inadequate performance during the factor identification activities.

Technical problems identified by the p l a n t staff or the C P E evaluator, and the potential costs associated w i t h correcting these problems, often serve as the basis for assessing administrative factors 1 i m i t i n g p l a n t performance. For example, the plant staff may have correctly identified needed minor modifications for the f a c i l i t y and presented those needs t o the POTW

46

admin is t ra tors , b u t had t h e i r request turned down. The eva lua tor should s o l i c i t t h e other s ide o f t h e s t o r y from t h e admin is t ra to rs t o see i f t h e a d m i n i s t r a t i v e pol i c y i s indeed nonsupport ive i n c o r r e c t i n g the problem. There have been many instances i n which operators o r p l a n t superintendents have convinced admin is t ra to rs t o spend money t o ' 'cor rect" problems t h a t r e s u l t e d i n no improvement i n p l a n t performance.

Another area i n which a d n i n i s t r a t o r s can s i g n i f i c a n t l y , even though i n d i r e c t l y , a f f e c t p l a n t performance i s through personnel mot ivat ion. If admin is t ra to rs encourage professional growth through support o f t r a i n i n g , t a n g i b l e awards f o r i n i t i a l o r upgrading c e r t i f i c a t i o n , etc., a Dosi t i v e in f luence ex is ts . If, however, a d n i n i s t r a t o r s e l i m i n a t e o r skimp on essent ia l operator t r a i n i n g , downgrade operator posi t i o n s through substandard sal a r ies , o r otherwise prov ide a negat ive i n f l u e n c e on operator morale, admin is t ra tors can have a s i g n i f i c a n t det r imenta l e f f e c t on o v e r a l l p l a n t performance.

3.5.2 Design Factors

Data gathered dur ing the p l a n t tour , completed Form D-3, and the prev ious ly completed eva lua t ion o f major u n i t process c a p a b i l i t i e s prov ide t h e bu lk o f the in fo rmat ion needed to complete the i d e n t i f i c a t i o n and p r i o r i t i z a t i o n o f des ign-re la ted performance-1 i m i t i n g factors . However, t o complete t h e eva lua t ion o f design f a c t o r s i n many CPEs, t h e eva lua tor must make f i e l d i n v e s t i g a t i o n o f t h e operat ional f l e x i b i l i t y o f t h e var ious u n i t processes.

F i e l d i n v e s t i s a t i o n s should be completed i n cooperat ion w i t h t h e POTW operator. The evaluator must n o t make any changes ' u n i l a t e r a l l y . Any f i e l d t e s t i n s des i red should be discussed w i t h t h e oDerator. whose cooperat ion should-be obtained i n making any needed changes. ' T h i s approach i s essent ia l since t h e eva lua tor may wish to implement changes t h a t , w h i l e improving p l a n t performance, c o u l d be det r imenta l to s p e c i f i c equipment a t the p l a n t . The operator has worked w i t h the equipment, r e p a i r e d past f a i l u r e s , and read the manufacturers' l i t e r a t u r e and i s i n the b e s t p o s i t i o n t o evaluate any adverse impact o f proposed changes.

F i e l d i n v e s t i g a t i o n o f process f l e x i b i l i t y de f ines t h e 1 i m i t a t i o n s o f t h e equipment and processes and a lso promotes a b e t t e r understanding o f the t ime and d i f f i c u l t y requ i red to implement b e t t e r process c o n t r o l . Th is i s i l l u s t r a t e d by the f o l l o w i n g discussion:

A 380 $ /d (0.1 mgd) extended a e r a t i o n f a c i l i t y has a i r l i f t sludge r e t u r n pumps t h a t have been operated t o p rov ide r e t u r n r a t e s o f 200-300 percent o f i n f l u e n t f low ra tes . The eva lua tor des i red to know i f r e t u r n s could be he ld under 100 percent s ince t h i s would s u b s t a n t i a l l y reduce s o l i d s load ing on the f i n a l c l a r i f i e r and p o t e n t i a l l y improve c l a r i f i e r performance.

Discussions w i t h the p l a n t operator revealed t h a t he had p r e v i o u s l y t r i e d to reduce the r e t u r n r a t e by reducing the a i r to the a i r l i f t r e t u r n pumps. The operator abandoned the ideas because t h e a i r l i f t s

47

repeatedly plugged overnight when l e f t a t the low rates. The evaluator convinced the operator t o again t r y reducing returns so t h a t the limits of return sludge flow control available could be defined.

An a i r l i f t pump consists of a vertical pipe w i t h one end submerqed, usually 2-3 m (6-10 f t ) , i n the basin from which l i q u i d i s t o be pumped and an a i r supply t h a t introduces a i r i n t o the pipe near i t s lower end. Air introduced i n t o the pipe decreases the specific g rav i ty of the pipe contents ( a i r bubble and l i q u i d mixture), and the heavier l i q u i d i n the surrounding basin forces the air/ l iquid mixture u p the pipe. The pumping force created i s proportional to the differential weight inside and outside the pipe. Increased flow i s achieved by increasing the amount of a i r introduced thus reducing the specific g rav i ty of the mixture further and increasing the d r i v i n g force.

The air rate was i n i t i a l l y reduced to produce a return flow rate of 100 percent of incoming wastewater flow as measured by a bucket and stopwatch. The a i r l i f t return pumps plugged completely i n less t h a n 2 hours because, as the sludge thickened due to reduced flow, the specific g rav i ty increased. The air rate t h a t produced the desired flow w i t h thinner sludge was no longer adequate. The flow was reset to 100 percent by increasing the airflow substantially above the previous setting. An hour la ter the return flow rate was measured as 220 percent. Because the pumping rate affects specific g rav i ty and specific g r a v i t y , i n turn, affects the pumping rate, a "snowballing" effect was produced when the a i r l i f t pump was changed i n either direction. These resul t s supported the operator's contention t h a t return flow rates could n o t be controlled a t reasonable levels.

The a i r supply was again adjusted t o provide a flow rate halfway between the current and the desired rate. This setting allowed better control t o be exercised b u t p lugg ing s t i l l occurred w i t h existing sludge characteristics a t return sludge flows of less t h a n about 125 percent. I t was concluded t h a t this was the practical lower limit for return sludge flow rate control w i t h the existing fac i l i t i es and sludge character. To maintain a return sludge i n the range of 125-150 percent required frequent checking, including an evening check n o t before asked o f the operator. In th i s manner, p a r t - b u t not a l l - of the design 1 imi t a t ion could be overcome w i t h increased operator attention.

The areas i n a POTW t h a t frequently require field investigations t o determine process f l exibil i t y are:

1. Suspended Growth Systems

- Control of return sludge flow rate w i t h i n the ranges presented i n Table 3-5

- Control of aeration basin DO w i t h i n the ranges presented i n Figure 3-1

- S1 udge mass cont ro l by wasting expected sludge product ion presented i n Table 3-7, and ac tua l waste concen t r a t ions o r r e p r e s e n t a t i v e waste concen t r a t ions shown i n Table 3-8

- F1 ow spl i t t i n g t o prevent unnecessary over1 oading of ind iv idua l process units

- Avai lab le mode changes t o provide maximum use of existing f a c i l i t ies :

o Contact s t a b i l i z a t i o n when the f i n a l c l a r i f i e r appears t o be the most 1 imi t ing process

o P l u g flow when oxygen t r a n s f e r i s marginal

2. Tr ick1 ing Filters

- A1 t e r n a t e d isposa l methods f o r anaerobic d i g e s t e r supe rna tan t

- Abi l i t y t o lower sludge levels i n c l a r i f i e r s without t h i n n i n g o u t s ludge to concen t r a t ions t h a t would cause s ludge t rea tment o r handl ing probl ems

- Reci rcu la t ion to the f i l t e r without excess hydraul ic l oads on the primary .or secondary c l a r i f i ers

3. RBCs

- A1 t e r n a t e disposal methods f o r anaerobic d i g e s t e r superna tan t

- A b i l i t y t o lower s ludge levels i n c l a r i f i e r s without t h inn ing o u t sludge t o concen t r a t ions t h a t would cause sludge treatment o r handl ing problems

- Abil i t y t o r e d i s t r i b u t e individual s t a g e load ings t o provide u n i t loadings w i t h i n the ranges shown i n Table 3-13

4. ABFs - - Control o f return sludge flow r a t e s w i t h i n 50-100 percent of

inf luent flow

- A b i l i t y t o waste a precise mass o f s ludge on a d a i l y basis

- A b i l i t y t o spread a d a y ' s s ludge wasting over a 24-hour per iod ,

- A b i l i t y t o provide r e c i r c u l a t i o n d i r e c t l y around the b ioce l l

o r a t l e a s t an extended period o f time

- A b i l i t y t o maintain a e r a t i o n basin DO a t 2-3 mg/l

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3.5.3 Operat ion Fac to r s

S i g n i f i c a n t performance-1 imi t ing f a c t o r s o f t e n exist i n the process con t ro l a c t i v i t i e s of POTW u n i t processes ( 4 ) ( 1 1 ) . The approach and methods used i n maintaining process cont ro l can s i g n i f i c a n t l y a f f e c t the performance o f p l a n t s t h a t have adequate physical f a c i l i t i e s . This s e c t i o n provides guidance t o eva lua to r s f o r i d e n t i f i c a t i o n and p r i o r i t i za t ion o f opera t iona l f a c t o r s t h a t 1 imi t pl a n t performance.

The e v a l u a t o r s t a r t s c o l l e c t i n g data f o r the process cont ro l eva lua t ion by iden t i fy ing the key POTW person f o r process con t ro l s t r a t e g i e s implemented a t the p l an t . The p l a n t tour and da ta-ga ther ing phases a l s o provide oppor tuni ty t o a s s e s s the process cont ro l appl ied . In a d d i t i o n , the process cont ro l c a p a b i l i t y of an ope ra to r capac i ty eva lua t ion . I f an their re1 a t i v e influence on i s indica ted . An approach fol lowing s e c t i o n s .

3.5.3.1 Suspended

can be’ s u b j e c t i v e l y assessed d u r i n g the process ope ra to r recognizes the u n i t process f u n c t i o n s and p l a n t performance, a good grasp o f process cont ro l to eva lua t ing process cont ro l i s discussed i n the

Growth F a c i l i t y Process Control

The process c o n t r o l s t h a t should be a v a i l a b l e to an ope ra to r of an a c t i v a t e d sludge f a c i l i t y a r e : sludge mass c o n t r o l , a e r a t i o n basin DO c o n t r o l , and return sludge r a t e con t ro l . Techniques and approaches t o improving these c o n t r o l s a r e presented i n Chapter 5.

a. Sludge Mass Control

The a c t i v a t e d sludge process removes c o l l o i d a l and d isso lved o rgan ic m a t t e r from wastewater r e s u l t i n g i n a net inc rease i n the s ludge s o l i d s i n the system. Control o f the amount o f s ludge maintained i n the system by wasting (removing) excess s ludge is a key element i n c o n t r o l l i n g p l a n t performance. All v a r i a t i o n s of the a c t i v a t e d s ludge process require s ludge mass cont ro l and p e r i o d i c wast ing. In l ine w i t h this requirement , an o p e r a t o r who proper ly understands a c t i v a t e d s ludge mass con t ro l should be ab le to show the eva lua to r a recorded h i s t o r y o f a c o n t r o l l e d s ludge mass, e.g., r eco rds o f mean cell residence time ( M C R T ) , mixed l i q u o r v o l a t i l e suspended s o l i d s ( M L V S S ) , p l o t s of a e r a t i o n t a n k concen t r a t ion i n the a e r a t i o n bas in , t o t a l mass o f s ludge i n the pl a n t , etc.

The fol lowing a r e common i n d i c a t o r s t h a t s ludge mass cont ro l i s no t app l i ed adequately a t an a c t i v a t e d s ludge p lan t :

- A s ludge mass i n d i c a t o r parameter o r c a l c u l a t i o n (MLVSS, MCRT, ~ t o t a l sludge units) i s no t r u n on a r o u t i n e basis (12) . Routine

would be d a i l y f o r an g,OOO d / d ( 2 mgd) o r l a r g e r p l a n t and 3 times a week f o r a 400 m / d (0.1 mgd) p lan t .

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- Only a sett led sludge t e s t i s used to determine w a s t i n g requirements, e.g., waste i f the 30-minute set t led sludge volume i n a graduated cy1 inder i s greater t h a n 600 mg/l.

- The operator does not re la te mass control to control of sludge se t t l i n g character is t ics and sludge removal performance, i .e. , sludge character.

- Significantly l e s s mass i s wasted t h a n produced; i .e . , the c l a r i f i e r s lose sol ids over the weirs routinely.

- Poor performance pers is ts and the mass of sludge maintained provides an MCRT significantly out of the ranges i n Table 3-21.

TABLE 3-21

TYPICAL MEAN CELL RESIDENCE TIMES FOR SUSPENDED GROWTH POTWs

Process Type

Convent i on a1 Aer a t i on Extended Aeration Contact Stabil i zation

Typical MCRT day S

6-12 20-40 10-30

b . Aeration Basin DO Control

The aeration b a s i n DO level i s a significant factor i n promoting the growth of e i ther filamentous or zoogleal-type sludge organisms (13). Higher DO tends to speed up or slow down the relat ive populations of these major organism types toward primarily zoogleal . Conversely, 1 ower DO encourages the growth of filamentous organisms and a b u l k y , slow se t t l i n g sludge.

A general guide1 ine for re la t ing sludge character is t ics t o DO concentration i n an aeration basin is presented i n Figure 3-1. This information can be used to evaluate the DO control approach a t the POTW under study.

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FIGURE 3-1

EFFECT OF AERATION BASIN 00 CONCENTRATIONS ON SLUDGE SETTLING CHARACTERISTICS

4

. 3

- \

E) 0 2 n 25 m 3

1

Oxygen Uptake Rate, mglllhr

52

The fo l lowing are common indicators t h a t aeration basin DO control i s n o t appl ied adequately a t an activated sl udge p l a n t :

- DO testing i s n o t run on the aeration bas in on a routine basis. Routine ranges from daily fo r an 8,000 m3/d ( 2 mgd) o r larger plant t o weekly for a 400 d / d (0.1 mgd) p l a n t .

- The operator does not understand or use the relationship between D O and sludge character; i .e . , sludge se t t l ing i s very slow and DO i s very low, or sl udge se t t l i n g i s very f a s t , ef f l uent i s t u r b i d , and DO i s very h i g h .

c. Return Sludge Control

The objective of return sludge control i s t o optimize sludge distribution between the aerator and secondary c l a r i f i e r to achieve and maintain good sludge character. The anoxic condition of the sludge i n the secondary cl ari f i e r s i s usually not conducive t o producing desired sludge character.

--Thus, return sludge flow ra te control should be used t o maximize the sludge mass and sludge detention time i n the aeration basins and minimize the sludge mass and sludge detention time i n the c l a r i f i e r s .

The fo l lowing are common indicators t ha t return sludge flow ra te control - i s - not adequately applied a t an activated sludge plant:

- Returns are operated outside the ranges (especially higher) indicated i n Table 3-5 and Figure 3-2.

- The operator believes tha t a h i g h sludge blanket condition i n a f i na l c l a r i f i e r can categorically be improved by increasing the sludge return rate.

- MLSS concentrations fluctuate widely on a d i u r n a l basis, b u t return rates are n o t adjusted throughout the day to account for d iurna l flow variations.

- The operator has n o t devised a method t o estimate or measure the return sludge flow rate i f measurement was n o t provided for i n the original design.

- The operator does not realize tha t increasing the return sludge flow rate increases the solids loading to the final c l a r i f i e r and decreases the se t t l ing time i n the final c l a r i f i e r .

3.5.3.2 Fixed F i l m Facil i t y Process Control

There i s a lesser amount of process control t ha t can be applied to fixed fi lm f a c i l i t i e s than to suspended growth f a c i l i t i e s . However, because fixed film

53

E

FIGURE 3-2

T Y P I C A L RETURN SLUDGE FLOW RATES W I T H VARIOUS C L A R I F I E R SURFACE OVERFLOW RATES

$ ii 80 0

c

0 ' I I 1 I 1 I 1 1 8 12 16 20 24 28 32 36 40

Secondary Clarifier Surface Overflow Rate, mVm*/d

54

f a c i l i t y performance is so dependent on media l o a d i n g , process control , which may a t f i r s t seem unimportant, can make a s ignif icant difference i n plant performance. The following are common indicators t ha t process control a t a fixed film fac i l i t y i s not opt imum ( 1 ) ( 4 ) :

- Sludge blankets i n e i ther the primary or secondary c l a r i f i e r s are maintained a t a h i g h l eve l , i . e . , >0.3 m (1 f t ) .

- Organic loads from return process streams are n o t minimized despite poor p l a n t performance.

- Lack o f good maintenance, indicated by:

0

0

c- . 0

Distributors on trickl i n g f i l t e r s are plugged, d i s t r ibu tor seals are n o t fixed.

F i l t e r media i s par t ia l ly plugged and measures chlorination, flooding, and recirculation are not used the problem.

or 1 eaky

such as to address

Trick1 ing f i 1 ter underdrain col lec tor out1 e t s a re submerged or a i r vents are plugged.

- High recirculation, which increases primary or secondary c l a r i f i e r overfl ow rate.s , i s provided w i thout regard to cl ari f i e r overloading. Some trickl.ing f i l t e r plants provide recirculation t h a t i s directed to the raw wet-well and must pass t h r o u g h the primary c l a r i f i e r a second time as well as the t r ickl ing f i l t e r . Likewise, some t r ickl i n g f i l t e r s provide recirculation t h r o u g h the secondary c l a r i f i e r sludge return t o the head of the plant. Recirculation provided by these methods should not be used.

3.5.4 Maintenance Factors

General information on POTW maintenance i s gathered d u r i n g the detailed data collection phase and i’s recorded on Form D-5. However, the evaluation of maintenance performance-1 imi t i n g factors i s done throughout the CPE by observation and questioning concerning the re1 i a b i l i ty and service requirements o f pieces of equipment c r i t i ca l to process control and t h u s performance. If these units are out of service routinely or for extended periods of time, maintenance practices may be a d i rec t cause of , or a significant contributlng cause to , a performance problem. An adequate spare p a r t s inventory, to prevent undue %del ays i n restoring c r i t i ca l process functions while awaiting arrival of parts on order, i s essential t o the conduct of a good maintenance proqram. Equipment breakdowns a re often used as excuses for process control problems. For example, one operator of an activated sludge plant blamed the repeated loss of sludge over the f ina l c l a r i f i e r weirs on the periodic breakdown of one sludge return pump. Even w i t h one pump out of service, the return sludge capacity was over 200 percent of influent flow. The real cause of the sludge loss was inadequate process

5 5

c o n t r o l , i n c l u d i n g inadequate sludge mass c o n t r o l and excess ive ly h i g h r e t u r n s l udge f l o w ra tes .

Observation and documentation are necessary p o r t i o n s o f t h e approach u t i 1 i z e d t o evaluate emergency and p reven t i ve maintenance p rac t i ces . Impor tant aspects are examination and v e r i f i c a t i o n o f spare p a r t s i n v e n t o r i e s and recordkeeping systems. An example approach t o a p reven t i ve maintenance schedul i n 9 system t h a t has been a p p l i e d success fu l l y a t several p l a n t s i s presented i n Appendix G. A good p reven t i ve maintenance program inc ludes a schedule to d i s t r i b u t e the workload evenly. Eva lua t i on o f these i tems prov ides a bas i s f o r d i scuss ion from which the s p e c i f i c r e s u l t s o f maintenance, o r l a c k o f maintenance, o f t he u n i t processes can be assessed. This approach i s i l l u s t r a t e d by the f o l l o w i n q :

A p o o r l y per forming t r i c k 1 i n g f i 1 t e r p l a n t has acceptable organic loadings t o the f i l t e r and very capable secondary c l a r i f i e r s , b u t a l so has a l a r g e b u i l d u p o f sludge i n b o t h the pr imary and secondary c l a r i f i e r s . The excessive amount o f s l udge i n t h e c l a r i f i e r s i n d i c a t e s t h a t inadequate process c o n t r o l by the opera to r m igh t be c o n t r i b u t i n g t o - _ _ poor p l a n t performance. However, i f sludge i s n o t removed adequately because the heated anaerobic d i g e s t e r s a re upset every t ime t h a t more than a normal amount o f sludge i s added, a d i g e s t e r ope ra t i on o r l oad ing problem cou ld be suspected. F u r t h e r i n v e s t i g a t i o n revealed t h a t the b o i l e r i s being operated manually and j u s t d u r i n g t h e day because the opera to r had t r i e d unsuccessfu l ly t o f i x the automatic c o n t r o l s. Thus , inadequate maintenance i s i n f a c t a cause o f poor p l a n t performance.

The above d iscuss ion i l l u s t r a t e s how a maintenance-related problem can i n i t i a l l y be i d e n t i f i e d as something e l se and requ i res c a r e f u l eva lua t i on t o i d e n t i f y the t r u e cause o f poor p l a n t performance. Often, i n v e s t i g a t i o n o f maintenance schedul i n g records, work o rde r procedures, and spare p a r t s i n v e n t o r i e s prov ides an adequate assessment o f maintenance p rob l ems 1 i m i t i n g performance. The eva lua to r must, t h e r e f o r e , eval uate maintenance d u r i n q a1 1 phases o f t h e CPE and should n o t expect to i d e n t i f y these f a c t o r s s o l e l y i n a formal eval u a t i o n o f maintenance procedures.

3.6 Performance Eva1 u a t i o n

The p l a n t performance e v a l u a t i o n i s d i r e c t e d toward two goals: 1) establ i s h i ng , o r v e r i f y i n g , t h e magni tude o f a POTW' s performance problem; and 2 ) p r o j e c t i n g the l e v e l o f improved treatment t h a t can be expected as the r e s u l t o f implementing a CCP.

3.6.1 Magnitude o f the Performance Problem

During the CPE, t h e evaluator should develop a c l e a r understanding o f t h e performance problem associated w i t h the sub jec t POTW. As a f i r s t step o f t h i s assessment, recorded h i s t o r i c a l performance data can be used. These data are

56

available from copies of NPDES permit reports i n small POTWs and from monthly monitoring summary sheets i n 1 arger POTWs.

Once his tor ical data are reviewed, the evaluator should attempt to verify the accuracy of the reported plant performance. I t should be stressed t h a t the purpose i s not t o blame the individual responsible, b u t rather t o a s s i s t i n i d e n t i f y i n g and substantiating the true cause( s) of poor plant performance.

The evaluator can i n d i r e c t l y co l l ec t data to es tabl ish authenticity of the monitoring results throughout the CPE. For example, major u n i t processes are assessed fo r the i r capabili ty to achieve desired performance. If a POTW i s rated a Type 3 pl ant ( inadequate major process capabil i t y ) , recorded excel 1 ent e f f l uent qual i t y shoul d be suspect. If recorded performance i s consi s t en t w i t h the results of the overall evaluation, the va l id i ty and accuracy of the data are reinforced. Limitations of these comparisons a re their subjective nature.

Fortunately , recorded monitoring data accurately represent the t rue performance i n many plants. Small activated sludge plants have been shown t o have the most variance between h i s tor ical records and actual performance.

In small activated sludge plants - such as package extended aeration plants and contact s tab i l iza t ion plants and oxidation ditches - several days' or even an en t i r e week's sludge production can be l o s t a s the result of sludge b u l k i n q i n a single afternoon. Effluent SS may be l e s s than 10 mg/l before and a f t e r b u l k i n g occurs, b u t may reach 1,000-2,000 mg/l while b u l k i n g . Yet there i s suf f ic ien t time between b u l k i n g periods t o co l l ec t more than enough samples to meet permit monitoring requirements and show a good effluent quali ty. T h i s s i tua t ion is frequently revealed d u r i n g the evaluation of major u n i t processes when expected sludge production i s compared to actual sludge wasted o r when b u l k i n g i s actually observed d u r i n g the CPE.

Another sampl i n g procedure tha t can result i n nonrepresentative monitoring i s sometimes seen i n f ixed film f a c i l i t i e s where performance degrades significantly d u r i n g peak daytime loads. Samples collected from 6 a.m. t o 10 a.m. may meet the required compositing c r i t e r i a (e.g. , three samples a t 2-hour increments") , b u t would probably indicate better than overall average eff luent quality. Likewise, samples collected from Noon t o 4 p.m. may indicate worse than actual average eff luent quali ty.

Occasionally, e r ro r s i n laboratory procedures will cause a discrepancy between reported and actual eff luent quali ty. A quick review by an evaluator experienced i n laboratory procedures may ident i fy a problem and a s s i s t the analyst as well as provide the evaluator i n s i g h t in to what the true analytical results should be. Major test parameters c r i t i c a l fo r completion o f the CPE are influent BOD5 and flow. The evaluator can roughly check both BOD5 and flow data by calculating a per capita BOD5 contribution. Per capita BOD5 contributions are usually 0.07-0.09 k g (0.15-0.20 1 b ) / d for typical domestic wastewater. When estimating BOD5 loads to a plant without actual data, or checking reasonableness of existing plant data, loads from s igni f icant industrial contributors must be added t o the calculated per capi ta loads.

57

3.6.2 Projected Improved Performance w i t h a CCP

The plant performance t h a t i s achievable through implementation o f a C C P i s i n i t i a l l y estimated by evaluating the capabil i t y of major u n i t processes. If major u n i t processes are def ic ient i n capacity, secondary treatment cannot be achieved w i t h a CCP and the existing POTW i s incapable of achieving the desired performance; i .e . , i t i s a Type 3 plant.

I f the evaluation of major u n i t processes shows tha t the major f a c i l i t i e s have adequate capacity, the CCP approach i s applicable and can l ike ly be used t o achieve improved POTW performance; i .e., i t i s a Type 1 or Type 2 plant. For pl ants of t h i s type, a1 1 other performance-1 imi t i n g factors a re considered as possible t o correct w i t h adequate training of the appropriate POTW personnel. The training i s addressed toward the operational s t a f f for improvements i n pl ant process control and maintenance; toward the POTW administration f o r improvements i n administrative pol i c i e s and budget 1 imitations; and toward b o t h operators and adninis t ra tors to achieve minor design modi f icat ions. "Training" as used i n this context describes a c t i v i t i e s whereby information is

- - - - provided to f a c i l i t a t e understanding and encourage implementation of the C C P approach.

Once the p lan t ' s major u n i t process capabili ty has been established and the performance-1 imi t i n g factors have been identified and priori t ized, the evaluator is i n a position to assess the potential for improved performance w i t h implementation of a CCP. During this e f f o r t , the evaluator must assess the prac t icabi l i ty and potential time frame necessary to address each identi f ied factor. Additional ly , i t i s necessary to project 1 eve1 s of e f f o r t , a c t i v i t i e s , time frame, and costs associated w i t h the CCP implementation. On occasion, for Type 1 and Type 2 plants, the approach to addressing a performance-limiting factor may be so unreasonable as t o discourage a recommendation to implement a C C P ; i . e . , the number and/or magnitude of minor modifications exceeds the POTW's f u n d i n g capabili ty.

3.7 Presentation to POW Adninistrators and Staff

Once the evaluator has completed the fieldwork f o r the CPE, a meeting should be h e l d w i t h the POTW adninis t ra tors and s ta f f . A presentation of preliminary CPE results should include brief descriptions of the following:

- Evaluation of major u n i t processes (Type 1, 2, o r 3 ) - Priori t i zed performance-1 imi t i n g factors - Performance potential w i t h a CCP

I f a CCP appears warranted, the evaluator should discuss the specific performance-limiting factors t h a t the C C P will address and ask fo r local o f f i c i a l s ' s u p p o r t on how the identified factors can be eliminated. The a t t i t ude of the s t a f f i s c r i t i c a l to the success of the C C P , par t icular ly i n border1 ine cases where the evaluator feel s a CCP can def in i te ly he1 p . b u t where process control has to be precise and requires f u l l cooperation from the POTW

58

operating s t a f f . If the s taff i s n o t behind the CCP approach, the CCP wi l l take longer, require more qualified leadership, and may have t o include some POTW personnel changes to be successful. The adminis t ra tors s h o u l d realize these requirements before deciding on a course of action.

In general , i t i s desirable to present a l l f i n d i n g s a t the meeting w i t h local o f f i c i a l s . This approach eliminates s u r m s e s when the CPE report i s received and begins the cooperative approach necessary for implementing a CCP. In s i tuat ions where administrative or s t a f f factors a re d i f f i c u l t to present, the evaluator must use good judgment i n presenting the resul ts . Throughout the discussions, the evaluator must remember t h a t the purpose of the CPE i s t o identify and describe facts to be used t o improve the current s i tuat ion, n o t t o place blame for any p a s t or current problems.

I t shou ld be made clear t h a t , d u r i n g conduct of the C C P , other factors are often identified and must be addressed t o achieve the desired performance. The CCP approach targets plant performance as the end p o i n t , and any factors that interfere w i t h achieving this goal must be addressed whether they were identified d u r i n g the CPE o r no t . This understanding i s often missed by local o f f i c i a l s , and e f fo r t s may be developed to address only the items priorit ized

---during the CPE. The evaluator should s t r e s s t ha t a local commitment must be made to achieving the desired improved performance, not to addressing a " laundry 1 ist" of currently identified problems.

3 .8 C P E Report

The objective of a CPE report i s t o summarize the CPE findings and conclusions. I t i s particularly important t h a t the report be kept brief so tha t the maximum amount of resources are used for the evaluation rather t h a n f o r preparing an all- inclusive report. The report should present the impor tan t CPE conclusions necessary to allow the decisionmaking o f f i c i a l s to progress toward achieving desired performance from the i r fac i l i ty . E i g h t to twelve typed pages a re generally suff ic ient for the text of a CPE report. An example C P E report i s presented i n Appendix C. Typical contents are:

- Introduction - Facil i t y background - Major u n i t process eval uation - Performance-1 imi t i n g factors - Projected impact of a CCP - CCP cos ts

The CPE report should be distributed' t o POTW administrators and key plant personnel, as a m i n i m u m . Further distribution of the report, e.g., to the design engineer or regulatory agencies, depends on the circumstances of the C P E b u t should be done a t the direction, or w i t h the awareness, of local admi n i s t r a to r s .

59

3 .8 .1 Introduction

The introduction of the C P E report shou ld be brief and cover the fo l lowing topics:

- Reason(s) f o r the CPE - Objectives of the C P E - P1 a n t eff luent performance requirements

3 . 8 . 2 Facil i t y Background

T h i s section s h o u l d include general information about the POTW t h a t will serve a s the reference basis for the remainder of the report. The fo l lowing information shoul d be included as a m i n i m u m :

- POTW description ( o x i d a t i o n ditch, RBC, e t c . ) - Design and current flows - Age of p l a n t and dates of upgrades - Service p o p u l a t i o n - Significant indus t r i a l wastes - Significant i n f i l tration/inflow - U n i t process a n d / o r flow diagram - S t a f f number and p l a n t coverage

c-

3 . 8 . 3 Major U n i t Process E v a l u a t i o n

T h i s section should include a description of the p l a n t type (Type , 2 , o r 3 ) and a summary of data sources for calculating current loading. For example, ''current loadings were calculated using p l a n t 1 aboratory resul ts for concentrations and plant flow records lowered by 10 percent to adjust for h i g h cal i bration of flow recording equi pment .'I

Results should be presented for each major u n i t process (aerator , secondary c l a r i f i e r , sludge h a n d l i n g capabi l i ty) . The evaluator may choose to present capacit ies of other u n i t processes i f these data are pertinent to assessing the POTW' s treatment capabil i t y .

3 .8 .4 Performance-Limi t i n g Factors

Factors l i m i t i n g performance tha t were identified d u r i n g the CPE should be l i s ted . Generally, the more serious factors (those receiving "A" o r "B" r a t ings ) are l i s t ed i n order of p r i o r i t y and short , two- or three-sentence explanations of each are incl uded.

60

3.8.5 P ro jec ted Impact o f a CCP

The expected impact o f a CCP on p l a n t performance i s discussed b r i e f l y w i t h re fe rence t o t reatment requirements. Any a d d i t i o n a l bene f i t s , such as reduc t i on i n energy consumption, improved safety , etc. , should a1 so be i nd i ca ted .

3.8.6 C C P Costs

Costs associated w i t h a CCP should be p ro jec ted as accura te ly as poss ib le . Ranges o f cos ts can be used i f an eva lua tor does no t f ee l comfor tab le p r o j e c t i n g s p e c i f i c d o l l a r amounts. Each c o s t p ro jec ted should be i nd i ca ted as a "one-time" o r ' 'annual" cos t . Costs f o r a CCP f a c i l i t a t o r ( c o n s u l t a n t ) o r f o r a p i p i n g m o d i f i c a t i o n are examples o f "one-time" costs . Increased sludge handl ing and e l e c t r i c a l o r chemical c o s t s are examples o f ' 'annual" cos ts .

3.9 Example CPE

A 4,500 d / d (1.2 mgd) o x i d a t i o n d i t c h serves a p r i m a r i l y r e s i d e n t i a l community w i t h a popu la t i on o f 8,500. The wastewater i s ma in ly domestic. The c i t y counc i l was n o t i f i e d by t h e State h e a l t h department t h a t a d i s t r i c t engineer ' -s f i e 1 d i nspec t i on r e p o r t has conf i rmed data prov ided i n the c i t y ' s sel f-moni t o r i n g r e p o r t s t h a t improved POTW performance i s requ i red t o meet the c i t y ' s NPDES p e r m i t requirements o f 30 mg/l (30-day maximum) f o r BOD5 and TSS.

A f t e r research ing several a1 te rna t i ves , t h e pub1 i c works d i r e c t o r recommended t o the c i t y counc i l t h a t a CPE be conducted t o determine the causes o f t h e i r performance problem and prov ide d i r e c t i o n i n se lec t i ng c o r r e c t i v e act ions. A consu l tan t who specia l i z e s i n conduct ing CPEs and CCPs was subsequently h i r e d t o conduct t he CPE.

3.9.1 P l a n t Data

A f l ow diagram i s presented i n F igure 3-3. The f o l l o w i n g data were ex t rac ted f rom the completed data c o l l e c t i o n forms as presented i n Appendix D.

DESIGN DATA

Design Flow:

Hydraul i c Capaci ty:

Organic Loading:

4,500 d / d (1.2 mgd)

11,300 $ /d (3.0 mgd)

900 k g (2,000 l b ) BOD5/d 900 k g (2,000 l b ) TSS/d

61

F I G U R E 3-3

FLOW D I A G R A M O F POTW I N EXAMPLE C P E

Raw Wastewater

Mechanical Bar 4 Screen

62

Prel iminary Treatment: Mechanical Bar Screen, Aerated Gri t Chamber

F1 ow Measurement: Parshall Flume, Sonic Level Sensor, S t r i p Chart Recorder

Volume - 4,500 2 (160,000 cu f t ) 02 Transfer - 1,800 k g (4,000 l b ) /d

Oxidation Ditch:

@ 38" C (100" F) w i t h 2.0 mg/l residual DO b rush rotors

Final C1 a r i f i e r s : Number of C1 a r i f i e r s - 2 Diameter -30 .7 m (35.0 f t ) Area - 90 (962 sq f t ) each Sidewater Depth - 2.7 m (9.0 f t ) Center Depth - 3.1 m (10.5 f t ) Center Feed and Peripheral Weirs

Di sinfection:

-- ~ .

S1 udge Return:

Number of Chlorinators - 2 Capacity - 113 k g (250 I b ) / d each Contact Basin - 142 d (37,500 gal )

C1 ari f i e r Scraper t o Center Hopper Number of Vortex Pumps - 2 Flow Control - 1.9-5.7 m3 (500-1,500 gal)/min Measurement - 90" V-notch Weir w/o Recording Sampling - Manual (3 Weir

Aerobic Digester: Volume - 680 m3 (180,000 g a l ) Sludge Removal - Bottom Pipe to Drying Beds Supernatant Removal - Mu1 ipl e-port Drawoff t o

Oxidat ion Ditch

S1 udge Drying Beds: Number of Beds - 8 Size - 15.2 m x 45.0 m (50 f t x 150 f t ) Dried Sludge Buried t o 0.5 m (1.5 ft) Summer Drying Time - 3 weeks Winter Drying El iminated December-March Subnatan t Returned t o Head of Plant

CURRENT LOADING

F1 ow:

Influent BODS:

Infl uent TSS:

190 mg/l or 680 k g (1,500 l b ) / d

205 mg/l o r 740 kg (1,600 1 b ) / d

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3.9.2 Major U n i t Process Eva1 u a t i o n

AERATOR

Hydrau l i c Detent ion Time: [(160,000 cu f t x 7.5)/(950,000 gpd)] x 24 = 30 h r

From Table 3-2, Score = 10 Do in ts

Organic Loading: [(1,500 lb/d)/(160,000 cu f t ) ] x 1,000 = 9.4 lb/d/1,000 cu f t

From Table 3-2, Score = 10 Do in ts

Oxygen A v a i l a b i l i t y : (4,000 l b 02/d)/(1,500 kg BODs/d) = 2.6 l b 02 / l b BOD5

From Table 3-2, Score = 10 p o i n t s

Aera tor Subto ta l = 10 + 10 + 10 = 30 p o i n t s

c- .

SECONDARY CLARIFIER

Conf igurat ion: C i r c u l a r w i t h Weirs on Wall

From Table 3-4, Score = 7 p o i n t s

Surface Overflow Rate: (950,000 gpd)/(1924 sq f t ) = 494 gpd/sq f t

From Table 3-4. Score = 10 Do in ts

Depth a t Weirs: 9.0 f t

From Table 3-4. Score = -3 Do in ts ~~

Return Sludge Removal: Scraped t o Center Hopper

From Table 3-4. Score = 8 p o i n t s

Return S1 udge Contro l :

From Table 3-5, Typica l Range i s 50-100% o f Raw Wastewater Flow.

Desired Range = (50% x 0.95 mgd) t o (100% x 0.95 mgd) = 0.47-0.95 mgd

Actual Range = (500 gpm x 1,440 x 10-6) t o (1,500 gpm x 1,440 x 10-6) = 0.72-2.16 mgd

Actual Return Sludge Control i s 50% (0.72 t o 0.95 mgd) o f Desired Range.

64

Return S1 udge Measurement Provided.

From Table 3-4. Score = 5 p o i n t s

Secondary C l a r i f i e r Subto ta l = 7 + 10 - 3 + 8 + 5 = 27 p o i n t s

SLUDGE HANDLING CAPABILITY

Control 1 ab i l i t y : Waste Vol ume Manual l y Calcu la ted Waste Stream Manual l y Sa'mpl ed

From Table 3-6, Score = 2 p o i n t s

Capacity:

a . Expected Sludge Production

U n i t Sludge Product ion, From Table 3-7:

BOD5 Removed = ( i n f l u e n t BOD5 - E f f l u e n t BOD5 Achievable*) x Flow

0.65 l b TSS/lb BOD5 removed

c- .

= (190 mg/l - 15 m g / l ) x (0.95 mgd) x (8.34) = 1,385 l b / d

Expected Sludge Mass = (0.65 l b TSS/lb BOD51 x (1 ,385 l b BODg/d)

Expected Sludge Concentrat ion, From Table 3-8: 7,500 mg/l

Expected Sludge Volume = (900 l b / d ) / ( 7 , 5 0 0 mg/l x 8.34 x

= 900 l b TSS/d

= 14,400 gpd

b. Percentage of Expected Sludge Product ion Each Process Can Handle

1. Aerobic Digester

From Table 3-9, s tandard f o r eva lua t ing aerobic d i g e s t e r s i s a hydraul i c de ten t ion time o f 15 days.

Sludge Volume Ex i s t ing Diges te r Can Handle = (180,000 ga1) / (15 days) = 12,000 gpd

Percentage of Expected S1 udge Production = (12,000 gpd)/( 14,4000 gpd) = 83 percent

*Assumed value f o r a well opera ted oxida t ion d i t c h f a c i l i t y .

65

2. Dry ing Beds

From Table 3-9, t h e standard f o r eva lua t i ng d ry ing beds i s the worst season turnover t ime as demonstrated by pas t experience. E s s e n t i a l l y , no d r y i n g i s experienced from December through March so t h a t beds operate o n l y as storage d u r i n g t h a t per iod. r e q u i r e d must f i r s t be c a l cu l ated.

Storage volume

D iges te r Hydraul i c Detent ion Time = D iges te r Vol ume/Sl udge Volume HDT = (180,000 ga1)/(14,400 gpd)

= 12 days

From Table 3-10, f o r HDT = 12 days, t o t a l s o l i d s r e d u c t i o n o f 14% and ou tpu t s o l i d s concen t ra t i on o f about 13,000 mg/l i s expected.

Sludge t o Dry ing Beds = (900 l b TSS/d) x (1.00 - 0.14) = 774 l b / d

Sludge Volume = (774 lb/d)/ (13,000 mg/l x 8.34 x = 7,140 gpd

Storage Capaci ty o f E x i s t i n g Beds = (8) x (50 f t x 150 f t x 1.5 f t ) = 90,000 cu f t

Storage Capaci ty A v a i l a b l e = (90,000 cu f t x 7.5)/(7,140 gpd) = 94 days

Storage Capacity Required = 31 (December) 31 (January) 28 (February) 30 (March)

= days

Drying bed capac i t y i s a v a i l a b l e f o r 8 months o f t h e year, b u t o n l y 78% (94/121) of r e q u i r e d storage capac i t y i s a v a i l a b l e du r ing the w i n t e r 4 months.

E x i s t i n g D r y i n g Bed Adequacy = [(4/12) x (7811 + [(8/12) x (loo)] = 26 + 67 = 93 percent

3. Haul ing

From discussions w i t h the POTW s t a f f and admin i s t ra to rs , "Haul ing d r i e d sludge i s n o t a problem. crew down to the p l a n t to help out."

I f we have to , we can g e t t he s t r e e t

Haul ing Adequacy = 100 percent

4. L a n d f i l l

From discussions w i t h the POTW s t a f f and admin i s t ra to rs , "If we can g e t i t through t h e beds, we can g e t r i d o f i t a t t h e l a n d f i l l .I'

L a n d f i l l Adequacy = 100 percent

66

c-

From the c a p a c i t y e v a l u a t i o n , the aerobic d i g e s t e r is the ''weakest l i n k " a t 83 percent capac i ty .

From Table 3-6, Score = 3 p o i n t s

Sludge Handling Capab i l i t y Sub to ta l = 2 + 3 = 5 po in t s

Scores f o r each major u n i t process a r e presented i n Table 3-22.

TABLE 3-22

SUSPENDED GROWTH MAJOR UNIT PROCESS CAPACITY EVALUATION FOR EXAMPLE CPE

P o i n t s Required P o i n t s Scored Tvoe 1 TVDe 2 TVDe 3

" I " I " .

Aeration Basin 30 13 -30 0 -12 <O Secondary C1 a r i f i e r 27 25-55 0-2 4 <O S1 udge Hand1 ing Capabil i t y 5 10-30 0- 9 <O

To t a l 62 60-115 20-59 <2 0

The da ta i n Table 3-22 i n d i c a t e t h a t the aerator, secondary c l a r i f i e r , and t o t a l p o i n t s scored f o r the example POTW a r e sufflcient to r a t e a Type 1 p l a n t . However, the p o i n t s scored for s ludge handling c a p a b i l i t y a r e only s u f f i c i e n t for a Type 2 r a t i n g . Therefore , the overall p l a n t r a t i n g i s Type 2. This r a t i n g i n d i c a t e s t h a t a C C P i s gene ra l ly a p p l i c a b l e and t h a t improvement i n p l a n t performance is l i k e l y , b u t t h a t improvement i n performance to the des i r ed 1 eve1 w i t h o u t any upgrade o f major processes cannot be determined u n t i l a CCP i s imp1 emented.

3.9.3 Performance-Limi t i n g Fac tors

T h e fol lowing performance-1 imi t i n g f a c t o r s were i d e n t i f i e d during the CPE and given rankings o f "A" or 'IB." Further ranking o f these i d e n t i f i e d f a c t o r s was a l s o completed a s i nd ica t ed by the number assigned to each f a c t o r .

1. Operator Applicat ion of Concepts and Tes t ing t o Process Control ( " A 1 ' )

Less s ludge was wasted t h a n was produced on a r o u t i n e b a s i s . Excess sludge p e r i o d i c a l l y bulked from the f i n a l c l a r i f i e r s . Mixed l i q u o r concen t r a t ions were monitored r o u t i n e l y , b u t the concept of control 1 i n g t o t a l s ludge mass a t a des i r ed level was no t implemented. Operation o f

67

return sludge flow rates a t excessively h i g h ra tes , typically 150-200 percent of wastewater flow, contributed to solids loss.

2. Sludge Wasting Capability ( " B " )

An undersized digester and dry ing beds t h a t do n o t provide adequate sludge disposal capabil i t y d u r i n g winter months resu l t i n inadequate sl udge wasting capacity .

3. Improper Technical Guidance ("B")

The above process control and inadequate sludge disposal si tuation continued despite annual p l a n t inspections by .the State d i s t r i c t engineer. "Periodic solids loss' ' was given the same emphasis i n the annual inspection reports as p l a n t housekeeping, timely submi t ta l of monitoring reports, leveling and cleaning of c l a r i f i e r weirs, and other items far removed from the true performance-1 imi t i n g problems and potential solutions.

4. Clar i f ie r ( " B " )

The final c l a r i f i e r s have sidewater depths of only 2.7 m (9.0 f t ) . T h i s shallow depth promises loss of sludge solids and makes precise sludqe mass and return control mandatory.

5. Performance Monitoring ( I 'B ' ' )

Performance monitoring samples were collected only d u r i n g periods when c l a r i f i e r s were n o t b u l k i n g sludge to conceal performance problems.

6. Familiarity w i t h Plant Needs ( " B a t )

Administrators were not famil i a r enough wi t h the plant requirements for performance and operations t o recoghie t h a t a performance problem even existed.

7. Process Control 1 a b i l i ty ( "B" )

Oversized return activated sludge pumps were provided i n the p l a n t design. This promoted poor operation w i t h excessively h i g h return flows and would require a modification to improve process control.

3.9.4 Potential Impact of a C C P

The most serious of the performance-limiting factors identified were process control oriented. The evaluation of major u n i t processes resulted i n a Type 2 r a t i n g because of marginal , b u t n o t drast ical ly def ic ient , sludge hand1 i n g capability. The POTW appears to be a good candidate for a CCP. T h i s recommendation should be presented to the c i ty council. Performance of the POTW can be improved w i t h a CCP. Cont inual compliance will depend on the

68

a b i l i t y t o dispose of adequate quant i t ies of waste sludge. Documentation of improved performance may be d i f f i c u l t because exis t ing monitor ing data do not r e f l e c t true pas t e f f luen t quali ty.

3.10 C P E Results

The success of conducting CPE a c t i v i t i e s can be measured by POTW administrators selecting an approach and imp1 ementing a c t i v i t i e s t o achieve the required performance from the i r wastewater treatment faci l i t y . If def in i te followup a c t i v i t i e s are not i n i t i a t e d within a reasonable time frame, the objectives of conducting a CPE cannot he achieved.

3.11 C P E Worksheets

Worksheets t h a t can be used fo r evaluating POTW capabi l i ty a r e presented in These worksheets are used to evaluate the capacity of

ex is t ing major u n i t processes, i .e. , ae ra tor , secondary c l a r i f i e r , and sludge handling system, and determine whether the POTW i s a Type 1, Type 2 , or Type 3 pl a n t .

c- Appendices L through 0.

3.12 References

When an NTIS number i s c i ted in a reference, t h a t reference i s avai lable from:

Na ti o nal Tec hn i c a1 In fo rma t i o n Se rv i c e 5285 Port Royal Road Springfi el d , VA 22161 ( 703 1 487 -4650

1.

2.

3.

Hegg, B. A . , K. L. Rakness, and J. R. Schultz. Evaluation of Operation and Maintenance Factors Limiting Municipal Wastewater Treatment P1 a n t Performance. EPA-600/2-79-034, NTIS No. PB-300331, U. S. Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnat i , OH, 1979.

Gray, A. C., J r . , P. E. Paul , and H. D. Roberts. Evaluation of Operation and Maintenance Factors Limiting Biological Wastewater Treatment P1 a n t Performance. EPA-600/2-79-087, NTIS No. PB-297491, U.S. Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnati, O H , 1979.

Hegg, B. A . , K. L. Rakness, and J. R. Schultz. A Demonstrated Approach f o r Improving Performance and Re1 iabi l i t y of Biological Wastewater

Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnati, OH, 1979.

Treatment P1 ants. EPA-600/2-79-035, NTIS NO. PB-300476, U.S.

69

4. Hegg, B. A., K. L. Rakness, J . R. Schu l t z , and L. D. Demers. Evaluat ion of Operation and Maintenance Fac to r s Limit ing Municipal Wastewater Treatment P1 a n t Performance - Phase 11. EPA-600/2-80-129, NTIS No. PB-81-112864, U.S. Environmental P ro tec t ion Agency, Municipal Environmental Research Laboratory, Cinc inna t i , OH, 1980.

5. Schu l t z , J . R . , B. A. Hegg, and K. L. Rakness. R e a l i s t i c Sludge JWPCF Production f o r Act ivated S1 udge P l a n t s W i t h o u t Primary C l a r i f i e r s .

54(10): 1355-1360, 1982.

6. Process Design Manual , Wastewater Treatment Fac i l i t ies for Sewered Small Communities. EPA-625/1-77-009. U.S. Environmental P ro tec t ion Agency, Center f o r Environmental Research Information, Cinc inna t i , OH, 1977.

7. Brenner, R. C., J . A. Heidman, E. J . Opatken, and A. C. Pe t r a sek , J r . Design Information on Rotat ing Biological Contactors . EPA-600/2-84-106, NTIS No. PB-84-199561, U.S. Environmental P ro tec t ion Agency, Municipal Environmental Research Laboratory, C inc inna t i , O H , 1984.

c- 8. Rakness, K. L. , J. R. Schul tz , B. A. Hegg, J. C. Cranor, and R. A. N i s be t . F u l l Sca le Evaluat ion o f Act ivated Bio-Fil ter Wastewater Treatment Process. EPA 600/2-82-057, NTIS No. PB-82-227505, U. S. Environmental P ro tec t ion Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1982.

9. A - Guide t o the Se lec t ion of Cos t -Effec t ive Wastewater Treatment Systems. EPA-430/9-75-002, NTIS Report No. PB-244417, U.S. Environmental P ro tec t ion Agency, Of f i ce of Water Program Operat ions, Washington, D C , 1975.

10. Process Design Manual, S1 udge Treatment and Disposal. EPA-625/1-79-011, U. S. Environmental Protect ion Agency, Center for Environmental Research Informat ion , C inc inna t i , OH, 1979.

11. S c h u l t z , J . R. Act ivated Sludge - Troubleshoot ing Techniques. Presented a t Rocky Mountain Water and Wastewater P l an t Opera tor ' s School, Boulder, CO, 1983.

12. West, A. W . Operational Control Procedures f o r the Act ivated Sludge Process - P a r t I 1 IA, Calcu la t ion Procedures. EPA-330/9-74-001C, NTIS No. PB-231598, U. S . Environmental Protection Agency, Cinc inna t i , OH, 1973.

13. Palm, J. C., D. Jenkins, and D. S. Parker. The Re la t ionsh ip Between Organic Loading, Dissolved Oxygen Concent ra t ion , and S1 udge S e t t l e a b i l i t y i n the Completely-Mixed Act ivated S1 udge Process. Presented a t the 5 1 s t Annual Conference, Water Pol 1 u t ion Control Federat ion, Anaheim, C A , 1978.

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CHAPTER 4

APPROACH TO CONDUCTING COMPOSITE CORRECTION PROGRAMS

4.1 Objective

The overall objective of a Composite Correction Program ( C C P ) i s t o improve the performance of an existing POTW (1). If the resu l t s of a Comprehensive Performance Evaluat ion ( C P E ) indicate a POTW i s a Type 1 p l a n t (see Figure 2-11, then the existing major u n i t processes have been determined t o be adequate to meet current treatment requirements. For Type 1 f a c i l i t i e s , the C C P focuses on systematically el imina t ing performance-1 imi t i n g factors to

---achieve the desired effluent qua l i ty . This can be done w i t h o u t long-term p l a n n i n g or major plant modifications ( 2 ) .

For Type 2 p l a n t s , the existing major u n i t processes have been determined t o be marginal b u t improved performance i s l ikely through the use of a C C P and the POTW may meet performance objectives w i t h o u t a major p l a n t upgrade. For these plants, the CCP focuses on. clearly defining the optimum capability of existing f a c i l i t i e s .

A factor t h a t influences the conduct of a CCP a t Type 2 plants i s the projected future growth i n the service area. In an area w i t h l i t t l e projected growth, there i s generally more incentive t o make existing f a c i l i t i e s perform adequately t o meet long-term needs. Also, implementation time i s n o t as important i n low- or no-growth areas. A CCP of 12 months' durat ion t h a t leads t o 1 ong- term adequate performance w i t h existing f a c i l i t i e s i s general l y we1 1 worth the time. Even i f the CCP does not achieve the desired effluent qua l i ty and some construction i s indicated, p l a n t administrators can be confident t h a t any such construction i s indeed necessary.

In a growth s i tuat ion, implementation of a CCP for a Type 2 p l a n t should closely parallel analysis of future treatment needs. The POTW s h o u l d be p l a n n i n g expansion while the existing p l a n t capability i s being verified by a CCP. This parallel e f fo r t will allow administrators t o make knowledgeable short-term decisions t h a t will be compatible w i t h long-term needs.

For Type 3 p lan t s , major construction i s indicated and a more comprehensive s tudy i s warranted rather t h a n a CCP. A study of t h i s type would look a t long- term needs, treatment a1 ternatives, potential 1 ocation changes, financing mechanisms, and other factors beyond the scope of a CCP.

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4.2 Methodol ogy

The methodology for conducting a C C P i s a combination of implementation of a c t i v i t i e s t h a t s u p p o r t process requirements and systematic training of the s t a f f and adnini s t r a to r s responsible f o r wastewater treatment (2-4).

4.2.1 C P E Results

The bas i s for implementation and training e f fo r t s i s the priorit ized l i s t of performance-1 imi t i n g factors t ha t was devel oped d u r i n q the CPE (see Section 2.2.3). For example, i f al l of the priorit ized factors were process control oriented ( h i g h l y u n l ikely) , the in i t i a l CCP e f f o r t would naturally be directed toward operator training i n process control. More commonly, a combination of performance-limiting factors i s identified d u r i n g the CPE and a combination of imp1 ementation/training ac t iv i t i e s i s therefore required. In a d d i t i o n , performance-limi t i n g factors not identified i n a CPE often become apparent d u r i n g conduct of the C C P and must be addressed to achieve the desired level -- of treatment ( 3 ) .

4.2.2 Process Control Basi s

The are-as i n which performance-limi t i n g factors have been broadly qrouped (admini s t ra t ion , design, operation, and maintenance) are a1 1 important in tha t a factor i n any one of these areas can individually cause poor performance. Although no one area i s more important t h a n any other, i t helps when implementing a CCP t o understand the relationship of these areas to each other and the the goal of achieving a good, economical effluent.

A d m i n i s t ra t ion , design, and maintenance ac t iv i t i e s a l l lead to a pl a n t physically capable of achieving desired performance. I t i s the operation, or more specifically the process control, t ha t takes a physically capable p l a n t and produces adequately treated wastewater, a s indicated by Figure 4-1.

A CCP continually focuses toward the goal of achieving desired p l a n t eff luent quality. I t often becomes d i f f i c u l t to pr ior i t ize the changes needed to achieve this performance level , .due to the typical mu1 t i p l e performance- l i m i t i n g factors t ha t exist. However, by focusing on the needs of the biological treatment process, as established through process control e f for t s , p r ior i t ies fo r changes t o achieve improved performance can be developed.

For example, i f good performance i n an extended aeration activated sludge plant cannot be maintained because bulky sludge has developed as a resu l t of inadequate oxygen transfer capability , bet ter performance requires meeting the oxygen deficiency. Limi ta t ions i n meeting process needs (inadequate D O ) establish the need for design changes. The p l a n t must be improved to the p o i n t where i t i s capable of providing an adequate level of DO t o allow desired performance to be achieved.

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FIGURE 4-1

RELATIONSHIP OF PERFORMANCE-LIMITING FACTORS T O ACHIEVING A PERFORMANCE GOAL

J I Administration 1 I Design 1 Maintenance

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On the o the r hand, a p l a n t may e x h i b i t ex tens i ve l i m i t a t i o n s i n qrounds maintenance and housekeeping. I f these 1 i m i t a t i o n s do n o t i n t e r f e r e w i t h meeting the needs o f the b i o l o g i c a l t reatment process, l o w p r i o r i t y f o r addressing these 1 i m i t a t i o n s i s i nd i ca ted .

F igu re 4 - 1 and the above example i l l u s t r a t e how the process c o n t r o l bas i s can be used to p r i o r i t i z e improvements i n phys ica l f a c i l i t i e s . Proposed improvements must a l l e v i a t e a d e f i c i e n c y i n t h e e x i s t i n g " incapable p lan t , " as i d e n t i f i e d by process requirements, so t h a t proqress toward the performance goal can be pursued. I n t h i s i~a,' t h e m o z t d i rect . a p v , Jach 9 i;nprovei' performance i s imp1 emented. Nonperformance-re1 ated improvements can p rooer l y be delayed u n t i l t he p l a n t has achieved the t reatment o b j e c t i v e f o r which i t i s intended.

4.2.3 Long-Term Involvement

Implementat ion o f a CCP i s a long-term e f f o r t , t y p i c a l l y i n v o l v i n g one year, f o r several reasons:

I n h e r e n t l y 1 ong response t imes associated w i t h making changes and ach iev ing s t a b i l i t y i n b i o l o g i c a l systems. B i o l og i ca l systems t y p i c a l l y respond s lowly t o process c o n t r o l adjustments t h a t a f f e c t t he environment i n which the microorganism p o p u l a t i o n 1 ives. New environmental c o n d i t i o n s eventual l y r e s u l t i n changes i n t h e re1 a t i v e numbers o f d i f f e r e n t microorganisms. A1 though some changes can be accomplished f o r a c t i v a t e d sludge systems i n t h e p e r i o d o f t h r e e t o f i v e MCRTs i t i s n o t uncommon f o r some changes t o take weeks and even months be fo re des i red s h i f t s i n mic roorgani sm popul a t i o n s a r e accompl i shed (6 1.

Time r e q u i r e d t o make phys i ca l and procedural changes. This i s e s p e c i a l l y t r u e f o r those changes r e q u i r i n g f i n a n c i a l expendi tures where governing board o r counc i l approval i s necessary.

Greater e f f e c t i v e n e s s o f r e p e t i t i v e t r a i n i n g techniques. Operator and a d n i n i s t r a t o r t r a i n i n g can be conducted under a v a r i e t y o f ac t u a l opera ti ng and admi n i s t r a t i ve experiences . Time r e q u i r e d f o r i d e n t i f i c a t i o n and e l i m i n a t i o n o f any a d d i t i o n a l pe r fo rmance- l im i t i nq f a c t o r s t h a t may be found d u r i n g the CCP.

4.3 Personnel Capabil i t i e s f o r Conducting CCPs

Persons responsib le f o r conduct ing a CCP must have a comprehensive understanding o f wastewater t reatment (see Sec t ion 2.3) as we l l as extens ive hands-on experience i n b i o l o g i c a l wastewater t reatment ope ra t i ons and s t rong capabi l i t i e s i n personnel mo t i va t i on . A u t h o r i t a t i v e understanding o f and experience i n , b i o l o g i c a l wastewater processes are necessary because t h e

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c u r r e n t s t a t e - o f - t h e - a r t i n b i o l oq i ca l t reatment leaves room f o r much i n d i v i d u a l judgment i n b o t h design and process c o n t r o l . For example, re ferences can be found t o support the use o f a v a r i e t y o f a c t i v a t e d sludge process c o n t r o l s t ra teg ies . Those responsib le f o r implementing a CCP must have s u f f i c i e n t process experience to determine which o f these i s most a p p l i c a b l e t o t h e POTW i n question. Leadership and m o t i v a t i o n a l s k i l l s are r e q u i r e d to implement changes requi red. These i n d i v i d u a l s must implement changes, d i r e c t a c t i v i t i e s , prov ide t r a i n i n g , se t p r i o r i t i e s , exerc ise judgment, and, i n general , f a c i l i t a t e those func t i ons t h a t l e a d to improved performance. The term " f a c i l i t a t o r " w i l l t h e r e f o r e be used t o descr ibe those i n d i v i d u a l s respons ib le f o r imp1 ementing a CCP.

I n d i v i d u a l s who r o u t i n e l y work i n the area o f improving wastewater t reatment p l a n t performance w i l l l i k e l y be bes t q u a l i f i e d t o be CCP f a c i l i t a t o r s . These persons are, t y p i c a l l y , engineers o r operators who have focused t h e i r careers on wastewater t reatment p l a n t t roub leshoo t ing and have gained experience i n c o r r e c t i n g d e f i c i e n c i e s a t several p l a n t s o f va r ious types. It i s impor tan t t h a t CCP f a c i l i t a t o r s have experience i n a v a r i e t y o f p l a n t s because t h e a b i l i t y t o recognize t r u e causes o f l i m i t e d performance i s a s k i l l developed on ly through experience. S i m i l a r l y , t h e successful implementation o f a

e- c o s t - e f f e c t i v e CCP i s g r e a t l y enhanced by experience.

By the very n a t u r e o f t he CCP approach, t h e CCP f a c i l i t a t o r must o f t e n address improved operat ion, maintenance, and minor design m o d i f i c a t i o n s w i t h personnel a1 ready respons ib le f o r these wastewater t reatment funct ions. A ' 'worst case s i t u a t i o n " i s one i n which t h e POTW s t a f f i s t r y i n g to prove t h a t " t h e f a c i l i t a t o r c a n ' t make i t work e i t h e r . " The CCP f a c i l i t a t o r must be able to g e t a l l p a r t i e s i nvo l ved t o focus on t h e common goal of achieving des i red p l a n t performance.

A CCP f a c i l i t a t o r must be able to conduct t r a i n i n g i n b o t h formal classroom and on-the- job s i t u a t i o n s . T r a i n i n g c a p a b i l i t i e s must a1 so be b road ly based, i.e., e f f e c t i v e w i t h b o t h the opera t i ng as w e l l as the a d m i n i s t r a t i v e personnel. When addressing process c o n t r o l 1 i m i t a t i o n s , t r a i n i n g must be geared to the s p e c i f i c process c o n t r o l dec i s iomakers . Some may be inexper ienced and u n c e r t i f i e d ; o t h e r s may have considerable experience and c r e d e n t i a l s. A d m i n i s t r a t i v e " t r a i n i n g " i s o f t e n a m a t t e r o f c l e a r l y p r o v i d i n g i n fo rma t ion t o j u s t i f y o r support CCP a c t i v i t i e s . A1 though many a d m i n i s t r a t o r s a r e competent, successful , and experienced, some may n o t know what t h e i r f a c i l i t i e s r e q u i r e i n terms o f manpower; minor m o d i f i c a t i o n s , o r s p e c i f i c funding needs.

CCP f a c i l i t a t o r s can be e i t h e r consu l tan ts o r u t i 1 i ty empl oyees. When l o c a l a d m i n i s t r a t o r s decide to use a c o n s u l t a n t to implement t h e CCP, they should conduct i n t e r v i e w s and check references thoroughly. Near ly every CCP i n v o l v e s c o r r e c t i o n o f some a d n i n i s t r a t i v e f a c t o r s , actual expenses t o the POTW, and c o u l d i n v o l v e a subs tan t i a l c o n s t r u c t i o n c o s t i f the CCP i s n o t capable o f b r i n g i n g t h e POTW to t h e des i red l e v e l o f treatment. As such, t he a d m i n i s t r a t o r s should have complete confidence i n the a b i l i t i e s of t he CCP f a c i l i t a t o r . An impor tant a t t r i b u t e o f a consu l tan t p r o v i d i n g CCP serv ices i s the a b i l i t y t o exp la in problems and p o t e n t i a l s o l u t i o n s c l e a r l y t o a v a r i e t y o f audiences, b o t h techn ica l and nontechnical .

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When l o c a l admin i s t ra to rs decide to conduct a CCP w i t h o u t the serv ices o f ou ts ide personnel, they should recognize t h a t some inhe ren t problems may e x i s t . The i n d i v i d u a l s implementing the CCP, f o r example, o f t e n f i n d i t d i f f i c u l t to prov ide an unbiased assessment o f t h e area i n which they normal ly work: ope ra t i ng personnel tend to look a t design and a d m i n i s t r a t i o n as problem areas; a d n i n i s t r a t o r s t y p i c a l l y f e e l t h e opera t i ng personnel should be a b l e to do b e t t e r w i t h what they have; t h e engineer who designed a f a c i l i t y i s o f t e n r e l u c t a n t to a h i t design l i m i t a t i o n s , e tc . These b iases should be recognized and discussed be fore personnel c l o s e l y assoc iated w i t h the POTW i n i t i a t e a CCP.

4 .4 Es t ima t ing CCP Costs

CCP c o s t s vary w ide ly depending on t h e s i ze and complex i ty o f t he f a c i l i t y , who imp1 ements the CCP, t h e number and na ture o f performance- l imi t i n g fac to rs , and t h e c a p a b i l i t y and cooperat ion a v a i l a b l e from the POTW techn ica l and a d m i n i s t r a t i v e s t a f f . The c o s t o f a CCP f a l l s i n t o two main areas: 1 ) c o s t o f a consu l tan t to implement t h e CCP; and 2 ) c o s t o f implementinq a c t i v i t i e s to -- suppor t the CCP e f f o r t , such as minor p l a n t mod i f i ca t i ons , a d d i t i o n a l s ta f f ing , more t e s t i n g equipment, and c e r t a i n process changes. Est imated c o s t s f o r us ing a CCP c o n s u l t a n t a r e presented i n Table 4-1.

TABLE 4-1

TYPICAL COSTS FOR CONDUCTING A CCPa

F a c i l i t v

F i x e d Fi lm:c <2,000 d / d (0 5 mgd) 2,000-38,000 d / d (0.5-10 mgd)

CCP Consu l tan t Cost - 3,000- 20,000 5,000- 50,000

15,000-1 00,000

3,000- 25,000 5,000- 80,000

aFor c o n t r a c t f a c i l i t a t o r . b I n c l udes a1 1 v a r i a t i o n s o f a c t i v a t e d sludge, and ABF systems. CInc ludes t r i c k l i n g f i l t e r s w i t h bo th p l a s t i c and rock media and

RBCs .

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Wide ranges a r e presented i n Tabl e 4-1 because the performance-1 imi t i n g f a c t o r s g e n e r a l l y vary widely from p l a n t t o p l a n t and r e q u i r e d i f f e r e n t t ypes and amounts of t r a i n i n g before they can be e l imina ted .

The costs of implementing a c t i v i t i e s t o support the C C P e f f o r t and f o r ope ra t ing the POTW a t a higher level of performance are d i f f i c u l t t o general ize. They must be developed on an individual POTW b a s i s s i n c e they a r e more dependent on the p a r t i c u l a r performance-1 imi t i n g f a c t o r s than the size or type of f a c i l i t y . In most CCPs these c o s t s equal o r exceed the typica l c o s t s of a C C P c o n s u l t a n t , a s presented i n Tabl e 4-1.

4 .5 References

When an NTIS number i s c i t e d i n a r e f e r e n c e , t h a t r e fe rence i s a v a i l a b l e from:

National Technical Information Se rv ice 5285 P o r t Royal Road Spr ing f i e ld , VA 22161 (703) 487-4650 -- . .

1. Hegg, B. A . , K. L. Rakness, and J. R. Schul tz . Evaluat ion of Operat ion and Maintenance Fac to r s L i m i t i n g Municipal Wastewater Treatment P1 a n t Performance. EPA-600/2-79-034, NTIS No. PB-300331, U. S . Environmental Pro t e c t i o n Lab ora t o ry , Cincinnat i , OH, 1979.

2. Hegg, B. A. , K. L. Rakness, and J. R. Schul tz . The C C P Way t o Better E f f l u e n t s . Water Engineering and Management, 129(10):40-43, 1982.

Ag enc y , Mu n i c i pa 1 En v i r o nmen t a1 Re search

3. Hegg, B. A. , K. L. Rakness, and J . R. Schul tz . A Demonstrated Approach f o r Improving Performance and Re1 i ab i l i t y o f Biological Wastewater

Environmental P ro tec t ion Agency, Municipal Environmental Research Laboratory, Cinc inna t i , OH, 1979.

Treatment P1 a n t s . EPA-600/2-79-035, NTIS NO. PB-300476, U.S.

4. Gray, A. C. , J r . , P. E. Paul , and H. D. Roberts. Evaluat ion o f Operation and Maintenance Fac to r s L i m i t i n g Biol ogical Wastewater Treatment P1 a n t Performance. EPA-600/2-79-087, .NTIS No. PB-297491 , U.S. Environmental P ro tec t ion ' Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1979.

5. Palm, J . C., D. Jenkins, and D. S. Parker . The Rela t ionship Between Organic Loading, Dissolved Oxygen Concent ra t ion , and S1 udge S e t t l e a b i l i t y i n the Completely-Mixed Act ivated Sludge Process . Presented a t the 5 1 s t Annual Conference, Water Poll u t ion Control Federat ion, Anaheim, C A , 1978.

6. Jenkins, D. and W . E. Garr ison. Control of Act ivated Sludge by Mean Cell Residence Time. JWPCF 40(11) : 1905-1919, 1968.

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CHAPTER 5

HOW TO CONDUCT COMPOSITE CORRECTION PROGRAMS

5.1 I n t r o d u c t i o n

This chapter presents techniques, schedules, and guide1 ines t h a t have been success fu l l y used i n implementing Composite C o r r e c t i o n Programs (CCPs). The methods presented should n o t be taken as t h e o n l y workable methods, s ince exper ience has shown t h a t no s i n g l e approach w i l l work a t every POTW (1). When implementing a CCP, i t must be remembered t h a t t h e concept o f c o r r e c t i n q -- Ferformance-1 i m i t i n g f a c t o r s u n t i l the des i red POTW Performance i s achieved must remain t h e c o n t r o l l i n g guidance, w i t h t h e s p e c i f i c s l e f t t o t h e CCP f a c i l i t a t o r .

5.2 C C P A c t i v i t i e s

A CCP f a c i l i t a t o r shoul d schedule per iods o f onsi t e involvement i n te rspe rsed w i t h o f f s i t e 1 i m i ted involvement. Dur ing t h e ons i te per iods, t h e f a c i l i t a t o r assumes a l eadersh ip r o l e i n making process c o n t r o l decis ions, ass ign ing r e s p o n s i b i l i t i e s , t r a i n i n g POTW s t a f f , and checking progress. When n o t ons i te , POTW personnel a re responsib le f o r t h i s l eadersh ip and the CCP f a c i l i t a t o r moni tors t h e i r progress as we l l as t h e process c o n t r o l and performance o f the p l a n t .

The CCP shoul d be scheduled and imp1 emented us ing the f o l 1 owing t o o l s , keeping t h e i r advantages and 1 i m i t a t i o n s i n mind:

- Telephone c a l l s , because o f convenience and low cos t , f o r r o u t i n e mon i to r i ng o f CCP progress. Use o f the telephone promotes acceptance by POTW personnel o f r e s p o n s i b i l i t y f o r making c r i t i c a l p l a n t observat ions, i n t e r p r e t i n g data, and summarizing impor tant i n d i c a t o r s and conclusions. The e f f e c t i v e n e s s o f telephone c a l l s i s l i m i t e d i n t h a t the CCP f a c i l i t a t o r must r e l y on observat ions o f t he POTW personnel r a t h e r than h i d h e r own. To ensure common understanding of the telephone conversat ions, t h e CCP f a c i l i t a t o r should a1 ways summari ze impor tant p o i n t s , deci s ions t h a t have been reached, and ac t i ons t o be taken subsequent t o the c a l l . Roth the CCP f a c i l i t a t o r and POTW personnel should keep w r i t t e n phone logs.

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- S i t e v i s i t s t o verify or c la r i fy p l a n t s ta tus , indicate major process control changes, t e s t completed f a c i l i t y modifications, provide onsite operator t r a i n i n g , and report progress t o POTW administrators. Specific dates for s i t e v i s i t s should be scheduled a s indicated by the p l a n t status and t r a i n i n g requirements.

- Written reports t o promote c l a r i t y and continuity. Because the cost of written reports depletes f u n d s available for action- oriented work by b o t h the POTW s t a f f and the CCP f a c i l i t a t o r , on ly concise, quarterly status reports are recommended. Short (1-page) written summaries shou ld also be prepared for each f a c i l i t y modification. In i t i a l ly , these may be prepared by the C C P f a c i l i t a t o r , b u t t h i s responsibil i ty should ultimately be transferred t o the POTW s t a f f .

- F i n a l CCP report to summarize ac t iv i t i e s , since a l l major recommendations should have been implemented d u r i n g the CCP. Current status of the POTW performance and capacity s h o u l d be presented.

-- The approach of interspersing onsi t e w i t h o f f s i t e involvement i s i l lus t ra ted i n Figure 5-1. As the C C P progresses, fewer s i t e visi ts and telephone c a l l s should be used. T h i s i s i n l i ne w i t h the transfer of responsibil i ty back to the permanent POTW s ta f f . Typical levels of e f f o r t required by CCP f a c i l i t a t o r s are presented i n Table 5-1. For any particular POTW, the level of e f fo r t i s dependent on the specific performance-limiting factors.

5.3 I n i t i a l S i te Visit

The i n i t i a l si te v i s i t i s used to establish the working relationship between the CCP f a c i l i t a t o r and the POTW s t a f f and administration. A good working relationship - based on m u t u a l respect , communication, and understanding of the CCP - greatly enhances the potential fo r a successful CCP.

5.3.1 C P E Results

I f the CCP f a c i l i t a t o r was not involved i n the C P E , 25-50 percent of the i n i t i a l s i t e visi t time may be required to re-create or confirm the conclusions of the CPE.

A CCP i s often implemented by individuals more experienced i n identifying and correcting factors 1 i m i t i n g POTW performance than those who conducted the C P E . Dur ing the in i t i a l s i t e visi t , the CCP f a c i l i t a t o r should schedule time w i t h key plant personnel and key administrators t o discuss confirmation and/or modification of the original performance-limi t i n g factors identified i n the CPE. T h i s discussion s h o u l d also address the Type 1 or Type 2 s ta tus of the POTW and the improvement i n plant performance and/or capacity expected from implementation of a CCP.

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FIGURE 5-1

TYPICAL SCHEDULING OF ONSITE AND OFFSITE INVOLVEMENT

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2

Telephone Consultation

. . I

Onsite Consul tat ion I

Months of Involvement

TABLE 5-1

TYPICAL CCP FACILITATOR INVOLVEMENT

I n i t i a l S i t e Telephone Add i t iona l F a c i l i t y S i ze and Type* V i s i t Consul t a t i o n S i t e V i s i t s

days no. /wk no. /y r i n i t i a l end

Suspended Growth : 3,800 d / d (1 mgd). 3- 5 2 -6 2 -4 4-1 2

38,000 d / d (10 mgd) 4-10 3-8 2 -4 6-20

F ixed F i l : 3- 8 5-12

2- 5 1-3 1-4 4-10 2-3 1-4

3,800 m J / d (1 mgd) 38,000 m3/d (10 mgd)

* Suspended growth f a c i l i t i e s have g rea te r process c o n t r o l fl e x i b i l i t y and t y p i c a l l y r e q u i r e a g rea te r l e v e l o f e f f o r t by t h e CCP f a c i l i t a t o r .

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The i n i t i a l s i t e v i s i t should a lso be used t o beain the e l i m i n a t i o n o f a l l major pe r fo rmance- l im i t i ng f a c t o r s ( r a t e d "A" o r "B" i n t h e CPE) and as many o the r f a c t o r s as poss ib le . It i s u s u a l l y most advantageous t o f i r s t work on improving process c o n t r o l . E x i s t i n g process c o n t r o l t e s t i n g should be reviewed and mod i f i ed so t h a t a l l necessary process c o n t r o l elements a re adequately moni tored. Sampl i n g frequency and l o c a t i o n , c o l 1 e c t i o n procedures , and l a b o r a t o r y analyses should be standardized so t h a t subsequent data c o l l e c t e d by POTW personnel and reviewed by t h e CCP f a c i l i t a t o r can be used t o evaluate the r e s u l t s o f CCP a c t i v i t i e s and represent the complete process c o n t r o l mon i to r i ng needs o f t h e POTW. New o r mod i f i ed sampling o r analyses procedures should be demonstrated by the CCP f a c i l i t a t o r and then performed by p l a n t personnel under t h e superv i s ion o f t h e CCP f a c i l i t a t o r .

5.3.2 M o n i t o r i n g Equipment

Any needed sampling o r t e s t i n g equipment should be obtained. The CCP f a c i l i t a t o r shoul d a s s i s t the POTW personnel i n o b t a i n i n g any requ i red a d m i n i s t r a t i v e approvals.

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5.3.3 Process Contro l Summaries

The CCP f a c i l i t a t o r should, w i t h the help o f p l a n t personnel , d r a f t a p rec i se weekly summary form f o r process c o n t r o l parameters and performance mon i to r i ng r e s u l t s . Monthly records are of ten a v a i l a b l e , b u t monthly data are too i n f r e q u e n t t o a l l ow t i m e l y process c o n t r o l adjustments. POTW personnel should prov ide t h e weekly summaries t o t h e CCP f a c i l i t a t o r throughout t h e CCP.

I n some small p lan ts , process c o n t r o l and mon i to r i ng r e s u l t s can o f t e n be recorded on a s i n g l e page. An example orocess c o n t r o l form used bo th f o r i n - p l a n t records and as a summary sent t o t h e CCP f a c i l i t a t o r i s shown i n F igu re 5-2.

5.3.4 Process Control Adjustments

The CCP f a c i l i t a t o r should, as much as poss ib le , i n i t i a t e process c o n t r o l adjustments du'r ing t h e i n i t i a l s i t e v i s i t . Where process c o n t r o l s are g ross l y o u t o f l i n e , e.g., 300 pe rcen t est imated r e t u r n sludge f lows, the CCP f a c i l i t a t o r should i n i t i a t e adjustments toward more reasonable values a t t h e e a r l i e s t poss ib le time. F i n e tun ing ' o f process c o n t r o l and t r a i n i n g o f t he POTW s t a f f cannot l e g i t i m a t e l y progress u n t i l t h i s f i r s t l e v e l o f e f f o r t i s i n i t i a t e d .

Dur ing major process c o n t r o l adjustments, every e f f o r t should be made to minimize adverse impact on t h e POTW opera to rs ' morale. Recommendations f o r process c o n t r o l changes should be explained i n terms o f a t tempt ing t o opt imize p l a n t c a p a b i l i t i e s through process adjustments w i t h bo th t h e CCP f a c i l i t a t o r

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F I G U R E 5-2

SAMPLE PROCESS CONTROL AND PERFORMANCE M O N I T O R I N G FORM FOR A S M A L L P O W

Week o f 19 PI ant Name

Ueekly Tue Wed Thur F r i Sat Sun Hon

Date Average

Flow, m3/d Return Flow, m3/d Aeration Basin Temp., OC Aeration Basin DO, mg/I Digester DO, mg/l Digester Temp. , % Aeration Basin Solids, mg/I Aeration Basin Mass, kg Return Sludge Conc., mg/I Cla r i f i e r Solids COnc., mg/l Cla r i f i e r Mass, kg Total Mass, kg m a i n Setting Sludge, m l / l Eff luent Turbidity, NTU Waste volume, m3 Waste Solids Conc., mg/l Waste Mass, kg Sludge Age, days Oxygen Uptake Rate, mg/l/hr Disposal Volune, 2 Disposal Sol ids Conc. , mg/I D i sposa I Mass , kg

Raw TSS, mg/l Final Q, mg/l Final TSS, mg/I Fecal C o l i , no./100 m i Final CI2, mg/I

Raw Q J mg/I

and POTW o p e r a t o r s involved i n a l l a spec t s . Even w i t h th i s approach, a CCP f a c i l i t a t o r should not expect t o ob ta in immediate complete support from POTW personnel on a l l changes. A response such a s "well , l e t ' s t r y i t then and see'' i s o f t en the best t h a t can be expected. Some changes may be made w i t h on ly the degree of consensus expressed by the s ta tement: ' ' I d o n ' t t h i n k i t ' l l work , b u t we can t r y i t . "

5.3.5 Minor Design Changes

Any minor design changes ident i f ied a s necessary by the C P E and confirmed by the CCP f a c i l i t a t o r should be i n i t i a t e d during the i n i t i a l s i te v i s i t . Minor design changes o f t e n require s i g n i f i c a n t amounts of time f o r approvals , de l ive ry o f p a r t s o r equipment, o r cons t ruc t ion . I t i s necessary, t h e r e f o r e , t o s t a r t the process a s soon a s needs a re ident i f ied so t h a t the e f fec t of any changes can be eva lua ted d u r i n g the ma jo r i ty o f the CCP.

5.4 Improving Design Performance-Limi t i n g Fac to r s c- -

The performance of Type 1 and Type 2 POTWs can o f t e n be improved by making minor mod i f i ca t ions o r a d d i t i o n s to the o r i g i n a l design. Examples o f design l i m i t a t i o n s identified i n a CPE a r e included i n Appendix H. Examples of common minor mod i f i ca t ions implemented d u r i n g CCPs a re :

- Return sludge flow measurement i n small a c t i v a t e d sludge POTWs

- Sample t a p s on sl udge drawoff 1 ines

- P i p i n g t o ope ra t e i n a l t e r n a t i v e a c t i v a t e d s ludge modes ( p l u g flow, c o n t a c t s t a b i l i z a t i o n , e t c . )

- Pip ing t o provide r e c i r c u l a t i o n without overloading c l a r i f i e r s

- Time c locks on waste and return sludge pumps

- Bypasses on "pol i sh ing" ponds

- Supplemental a i r i n a e r a t i o n bas ins

- Suppl emental sludge disposal - usual l y 1 and appl i c a t i o n capabi l i t y

5.4.1 I d e n t i f i c a t i o n and Justi f i c a t i o n

The CCP f a c i l i t a t o r and POTW personnel must be a b l e to j u s t i f y each proposed modi f ica t ion based on the r e s u l t i n g increased capac i ty o r o p e r a b i l i t y the modi f ica t ion will provide. The degree o f j u s t i f i c a t i o n required f o r each modi f ica t ion usua l ly v a r i e s w i t h the a s s o c i a t e d c o s t s and specific p l a n t

03

circumstances. For example, 1 i t t l e j u s t i f i c a t i o n may be r e q u i r e d t o convince a super intendent to add a sampling t a p i n a sludge l i n e i f t h e necessary s t a f f and t o o l s t o do the j o b are already a v a i l a b l e . The same tap would r e q u i r e more j u s t i f i c a t i o n i f a pa r t - t ime opera to r would have t o buy o r r e n t t o o l s and complete the i n s t a l l a t i o n on h i s / h e r own t ime o r o b t a i n a u t h o r i z a t i o n f o r a d d i t i o n a l p a i d t ime.

5.4.2 Imp1 ementation

The CCP f a c i l i t a t o r should ensure t h a t each minor design m o d i f i c a t i o n o r a d d i t i o n i s f o r m a l l y documented i n w r i t i n g . This documentation i s more va luable i n terms o f t r a i n i n g and commitment i f i t i s comDleted by POTW personnel . It should inc lude:

- Purpose o f the proposed change

- D e t a i l e d d e s c r i p t i o n o f the change

c- . - Q u a n t i t a t i v e c r i t e r i a f o r eva lua t i ng success o r f a i l u r e o f the change

- I n d i v i d u a l ( s ) responsib le f o r complet ing t h e change

- Cost est imate

- A n t i c i p a t e d improvement i n p l a n t performance

- Schedule

Another r o l e o f t h e CCP f a c i l i t a t o r i s t o a s s i s t POTW personnel i n understanding and implementing t h e i r responsib l i t y i n regard to the mod i f i ca t i on . I d e a l l y , t h e C C P f a c i l i t a t o r should be a techn ica l and managerial reference throughout the implementat ion o f t he m o d i f i c a t i o n , and the POTW s t a f f should have, o r develop, t h e techn ica l exper t i se , a v a i l a b l e t ime, and m o t i v a t i o n to complete the m o d i f i c a t i o n . I f t h e r e i s a breakdown i n complet ing assigned r e s p o n s i b i l i t i e s , t h e CCP f a c i l i t a t o r must become more aggressive i n assur ing complet ion o f the m o d i f i c a t i o n .

5.4.3 Assessment

F o l l o w i n g complet ion o f a minor mod i f i ca t i on , the CCP f a c i l i t a t o r should per form an e v a l u a t i o n o f t h e improved POTW c a p a b i l i t y . Th is assessment should compare the q u a n t i t a t i v e c r i t e r i a es tab l i shed f o r the p r o j e c t w i t h the c a p a b i l i t y o f t he actual m o d i f i c a t i o n . A one-page summary i s o f t e n h e l p f u l i n in forming, and ma in ta in ing support from, POTW personnel and admin i s t ra to rs .

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5.5 Improving Maintenance Performance-Limi t i n g Factors

P l a n t maintenance can generally be improved i n nearly a l l POTWs, b u t i t i s a serious performance-limiting factor i n only a small percentage of them (2-4) . Nevertheless, adequate maintenance i s essential to achieve consistent effluent q u a l i t y . As such, a C C P f a c i l i t a t o r may end u p improving the maintenance program d u r i n g a C C P t o ensure t h a t improved performance achieved d u r i n g a CCP i s maintained afterwards.

The f i r s t step i n addressing maintenance factors t h a t 1 imi t p l a n t performance is t o review any undesirable resu l t s of the current maintenance effor t . I f p l a n t performance i s degraded as a resu l t of equipment breakdowns t h a t could have been avoided w i t h better preventive maintenance, the problem i s easi ly documented. Likewise, i f h i g h cost of major corrective maintenance is experienced, a need for improved preventive maintenance i s eas i ly recognized. These si tuations should have been identified d u r i n g the CPE when f i l l i n g out the appropriate form i n Appendix D and identifying and p r i o r i t i z i n g performance-1 imi t i n g factors. However, many POTWs lacking good maintenance programs do not have such obvious evidence directly correlating poor

-maintenance practices w i t h poor performance. For these POTWs , maintenance would not have been identified a s a significant factor l i m i t i n g performance.

Once the need for improved preventive maintenance i s established, the next step i s t o ga in the. commitment of the plant operating s t a f f . Simply formalizing recordkeeping will generally improve maintenance practices t o an acceptabl e -1 eve1 i n many POTWs , particul arl y small e r ones.

A suggested four-step procedure for devel oping a maintenance recordkeepi ng system i s to: 1 ) l i s t a l l equipment; 2 ) gather manufacturers' l i t e r a tu re on a l l equipment; 3 ) complete equipment information summary sheets for a l l equipment; and 4 ) develop time-based preventive maintenance schedules.

A l i s t of equipment can most easi ly be developed by touring the POW. As new equipment i s purchased i t can be added t o the l i s t . E x i s t i n g manufacturers' l i t e r a tu re should be inventoried to identify missing b u t needed materials. Maintenance l i t e r a tu re can be obtained from the factory (usually a source i s identified on the equipment nameplate) or from local equipment representatives.

A n equipment information sheet i s presented i n Appendix G. Once sheets are completed for each piece of equipment, a time-based schedule can be developed. This schedule typically includes daily, weekly, monthly, quarterly, semiannual , and annual checkoff 1 i s t s of required maintenance tasks. An example of this scheduling system i s a l so presented i n Appendix G.

In many small POTWs, the number of pieces of equipment i s so small that scheduling i s not c r i t i c a l . In larger plants, preventive maintenance ac t iv i t i e s should be spaced to provide an even workload throughout the year. Similarly, a l l monthly maintenance ac t iv i t i e s s h o u l d be scheduled for accompl i shment over the en t i r e 4-week period.

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The above system f o r devel oping a maintenance recordkeepi ng system has worked success fu l l y a t several small POTWs. However, t he re are many o the r good maintenance references a v a i l ab le f o r use by CCP f a c i l i t a t o r s and POTW s t a f f s ( 5 - 7 ) .

5.6 Improving A d m i n i s t r a t i v e Performance-Limit ing Factors

Frequent ly encounteyed a d m i n i s t r a t i v e f a c t o r s t h a t 1 i m i t p l a n t performance are a d m i n i s t r a t o r s who a re unfami l i a r w i t h p l a n t needs and pol i c i e s t h a t c o n f l i c t w i t h p l a n t needs. For example, such i tems as minor m o d i f i c a t i o n s , t e s t i n g equipment, expanded operator coverage, o r increased u t i 1 i ty c o s t s may be recognized by p l a n t ope ra t i ng personnel as performance-1 i m i t i n g f a c t o r s b u t changes cannot be pursued due to l a c k o f a p p r e c i a t i o n o f t h e i r importance by nontechnical admin i s t ra to rs . Near ly a1 1 POTW admin i s t ra to rs want to p rov ide adequate t reatment capac i t y and performance. Thei r support and understanding i s essen t ia l t o t h e successful implementat ion o f a CCP. The f o l l o w i n g techniques have proven usefu l i n overcoming a d m i n i s t r a t i v e 1 i m i t a t i o n s :

- I n v o l v e p l a n t a d m i n i s t r a t o r s f rom t h e s t a r t o f t h e CCP. The i n i t i a l s i t e v i s i t should i nc lude t ime w i t h key admin i s t ra to rs a t the p l a n t to increase t h e i r understanding o f p l a n t processes and p rob l ems.

c- .

- Educate a d m i n i s t r a t o r s i n the fundamental s o f b i o l oq i ca l wastewater t reatment and i n the s p e c i f i c needs of t h e p l a n t ' s processes. Admin i s t ra to rs may be re1 u c t a n t t o pursue c o r r e c t i v e ac t i ons because o f l a c k o f understanding o f t reatment processes and the r o l e t h e des i red change p lays i n improv ing such processes.

- L i s t e n c a r e f u l l y t o t h e concerns o f a d m i n i s t r a t o r s so t h a t t hey can be addressed du r inq the CCP . Some o f t h e i r concerns o r ideas may be t e c h n i c a l l y u i impor tan t , b u t must be addressed t o ensure cont inued progress o f the CCP.

- Use techn ica l data based on process needs t o persuade admini s t r a t o r s t o take approp r ia te act ions; do n o t r e l y on " a u t h o r i t y . " A1 t e r n a t i v e s should be presented, when poss ib le , and the a d m i n i s t r a t o r s l e f t w i t h t h e decis ion.

5.7 Improving Operat ional Performance-Limi t i n g Fac to rs

Improvement o f POTW opera t i ons du r ing a CCP i s achieved by p r o v i d i n g t r a i n i n g w h i l e improved process c o n t r o l procedures, t a i l o r e d f o r the p a r t i c u l a r p l a n t , are developed and implemented. The i n i t i a l t r a i n i n g e f f o r t s should be d i r e c t e d a t the ke process c o n t r o l decisiornnakers. I n most p l a n t s w i t h f lows

a l l major process c o n t r o l dec is ions. I n these cases, on-the- job t r a i n i n g i s u s u a l l y more e f f e c t i v e than classroom t r a i n i n g and i s recommended. As t h e

l e s s than 1,900 m 3 / d (0.5 mgd), one person t y p i c a l l y makes and implements

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number of operators t o be trained increases w i t h D lan t s ize , the need f o r and effectiveness of combining classroom training w i t h on-the-job t r a i n i n g a1 so i nc rease s . As discussed i n Chapter 4 , process control i s the primary goal i n implementing a CCP because i t represents the essential step t h a t enables a capable plant to achieve the ultimate goal of cost-effectively producing a good q u a l i t y effluent. A detailed discussion of process control for suspended growth and fixed f i lm facil i t i e s i s therefore presented.

5.7.1 Suspended Growth Process Control

Process control of suspended growth facil i t i e s can be achieved t h r o u g h control o f the following important parameters associated w i t h the process:

- Activated sludge mass - Return sludge flow - Aeration basin DO

These items can be ut i l ized to apply ''pressure" to the biological environment. I f a particular pressure is held for an adequate lenqth of time t o qet biological system response, a desired change i n activated sludge character is t ics - such as se t t l ing velocity - will resul t . The inter- relationships between sludge character is t ics , pressure, and time for biological system response to occur re la t ive to sludge mass control , return sludge control , and DO control are discussed i n the following sections.

5.7.1.1 Activated S1 udge Characteristics

The primary objective of activated sludge process control i s achieving good performance by maintaining proper sludge character. Sludge character is defined as those physical and biological character is t ics of a sludge tha t determine i t s ab i l i t y to remove organic material from wastewater. Good sludge character requires filamentous and zoogleal bacteria t o be i n proper balance. Enough filaments should be present to form a skeleton for the floc par t ic les , b u t the filaments should n o t extend significantly beyond the floc.

More filaments tend to produce a slower se t t l i ng , larger sludge floc tha t produces a c learer supernatant. Too many f i 1 aments, however, produce a sl udge t h a t will not adequately s e t t l e and thicken i n the final c l a r i f i e r , often causing sludge to be carried over the c l a r i f i e r weirs. Having fewer filaments produces a more rap id se t t l ing sludge b u t also leaves more t u r b i d i t y . The f a s t e r se t t l ing , small sludge floc exhibits discrete se t t l ing and produces " p i n floc" o r "straggler floc" as well as higher tu rb id i t ies .

A representation of a microscopic view of this desirable type of sludge i s shown i n Figure 5-3.

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FIGURE 5-3 REPRESENTATIONS OF ACTIVATED SLUDGE FLOC

Desirable Activated Sludge Floc

Filament Backbone

Undesirable Slow-Settling Activated Sludge Floc

Filament Backbone

Extended Filament

Undesirable Fast-Settling Activated Sludge Floc

Dispersed Particle

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I t i s d e s i r a b l e t o obta in good s o l i d s / l i q u i d and the good s ludge th ickening c h a r a c t e r i s t i c s of a f a s t e r sett l ing s ludge along w i t h the h i g h q u a l i t y effluent produced by a slower set t l ing sludge. T h i s i s achieved by con t ro l of the s ludge c h a r a c t e r t o obta in the best balance of f a s t - and s low-se t t l i ng c harac t e ri s t i c s . S e t t l i n g tests can be used to monitor the s ludge cond i t ions shown i n F igure 5-3.

5.7.1.2 Act iva ted S1 udge Mass Control

Act ivated s ludge mass i s c o n t r o l l e d to achieve and maintain desired sludge c h a r a c t e r and, a s such, represents a c r i t i c a l a spec t of good process c o n t r o l . There a re severa l ways t o con t ro l s ludge mass i n a POW. These v a r i a t i o n s p u t emphasis on d i f f e r e n t c a l c u l a t i o n s o r different cont ro l parameters , b u t the bas i c o b j e c t i v e o f each i s t o obta in the desired mass o f microorganisms i n the system.

-Some mass cont ro l techniques a r e based on the assumption t h a t s ludge can best handle diurnal and day-to-day v a r i a t i o n s i n influent wastewater strength and the c y c l i c na tu re of sludge growth r a t e s by main ta in ing r e l a t i v e l y c o n s t a n t MLVSS concent ra t ion . Another technique a t t empt s to a d j u s t s ludge mass t o produce a desired food t o microorganism r a t i o (F/M). Yet another a t tempts t o maintain a c o n s i s t e n t average age of the a c t i v a t e d sludge i n the system, i .e. , mean cell res idence time (MCRT).

Mass cont ro l by monitor ing only the MLSS o r MLVSS concen t r a t ion i n the a e r a t i o n basin and wast ing s ludge t o maintain a desired level assumes t h a t v a r i a t i o n s i n the amount of s ludge i n the secondary c l a r i f i e r s i s in s ign i f i c a n t . A preferred approach includes secondary sl udge i n the mass cont ro l moni toring program.

The F/M method of s ludge mass cont ro l i s d i f f i c u l t t o implement because a method t o quick ly and accu ra t e ly monitor the food po r t ion o f th i s parameter i s n o t commonly a v a i l a b l e . Typ ica l ly , BOD5 o r chemical oxyqen demand ( C O D ) a r e used to i n d i c a t e the amount of food ava i l ab le . The BOD5 test r e q u i r e s f ive days t o complete and i s t h e r e f o r e u n s a t i s f a c t o r y f o r process cont ro l purposes. Although the COD test can be completed i n only several hours, i t requires equipment and l abora to ry c a p a b i l i t i e s t h a t a r e not usua l ly a v a i l a b l e i n small er pl an t s .

Mass con t ro l using the MCRT approach can be set up t o include the mass o f s ludge i n the a e r a t i o n basin and the secondary c l a r i f i e r (10). A v a r i a t i o n of this technique i s to select a desired level of t o t a l mass f o r the system ( i . e . , both the a e r a t i o n basin and secondary c l a r i f i e r ) and a d j u s t the amount of sludge wasted to approach the selected t o t a l mass. I t i s recommended t h a t one of these two s t r a t e g i e s be selected f o r c o n t r o l l i n g s ludge mass. The fol lowing d iscuss ion identifies the differences between the two s t r a t e g i e s .

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Activated sludge mass control using the MCRT approach requires t h a t the t o t a l sludge mass be measured each day and t h a t t o t a l be divided by the target MCRT. This calculated mass i s then attempted to be wasted. Actual MCRTs are calculated by d i v i d i n g the t o t a l sludge mass i n the system by the actual sludge mass wasted. Actual d a t a for a 3-week period of sludge mass control using the MCRT approach are shown i n Figure 5-4. During this period the target MCRT was kept constant a t 10 days. The da t a i n Figure 5-4 show t h a t fairly constant MCRT can be maintained. An advantage of mass control by this method i s t h a t i t requires d a i l y wasting.

Sludge mass control using the total mass i n the system approach requires t h a t wasting be varied depending on increases or decreases i n the t o t a l sludge mass. For example, i f the t o t a l sludge mass was increasing above the selected target level, wasting would be increased u n t i l the desired sludge mass was again achieved. Actual da t a for a 3-week period of sludge mass control using the target t o t a l mass approach are shown i n Figure 5-5. An important observation from Figure 5-5 i s t h a t total mass was held relatively constant despite i n d i v i d u a l MCRTs ranging from 10 t o i n f i n i t y (no wasting t h a t day) . Control of t o t a l sludge mass can be a useful process control parameter, especially i n activated sludge plants where wasting i s n o t done every day.

c- -

5.7.1.3 Return Sludge Flow Rate Control

The return sludge flow rate determines the distribution of sludge between the aeration basin and secondary clarifier. In general, return sludge flow rate control should be used t o maximize the sludge mass and sludge detention time i n the aeration basin and minimize the sludge mass and sludge detention time i n the f ina l clarifier. This represents the optimum condi t ion for an aerobic b io logica l treatment system and can be summarized as maximizing the sludge distribution ratio (aerator sludge mass divided by clarifier sludge mass).

A general misconception concerning the use of return sludge flow rates for process control is t h a t increasing the flow of return sludge decreases the sludge b l a n k e t level i n the secondary clarifier. This i s not as straightforward as i t f i r s t appears. W i t h i n the normal range of operation for sludge settl i n g characteristics, increasing the return rate will remove the sludge mass from the clarifier faster. However, the return sludge ultimately contributes to the t o t a l hydraulic load t o the clarifier and therefore t o the t o t a l solids load on the clarifier from the aeration basin (see Figure 5-6).

Depending on the sl udge settl i n g characteristics, increased sol ids 1 oad ing on the clarifier may or may not increase the solids mass i n the clarifier i n conjunct ion w i t h the faster solids .removal rate. A l t h o u g h the sludge detention time i n the clarifier may go down, the sludge mass i n the clarifier may go up. When the mass of sludge i n the clarifier i s increased along w i t h the rate of sludge removal, the objective of maximizing the sludge distribution ratio is obviously n o t achieved. The positive aspect o f a decreased detention time i n the clarifier must be weighed aga ins t the negative aspect of a decreased sludge distribution ratio and a decreased sludge detention time i n the aerator.

90

11

11

1

0

0

0 0 0

0 0 0

0

0

0 0

0

0 0

0

0 0

0

0

I I /I

I I,

91

26

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al A

ctiv

ated

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dge

Mas

s, k

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0

$2

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N-

A 0-

A

A-

A

VI

-

A a-

A

-4 A-

m

A a-

0

0

0

0 0

0

0

0

0

0

0

0

0

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0

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0

MC

RT,

day

s

FIGURE 5-6

SIMPLIFIED ACTIVATED SLUDGE PROCESS DIAGRAM

Q Aeration

Basin Clarifier

Q + R

Two l e v e l s o f improved sludge r e t u r n c o n t r o l are t y p i c a l l y encountered when implementing a CCP: gross adjustments t o b r i n g the opera t i on i n t o normal opera t ing ranges fo l lowed by f i n e tun ing t o op t im ize performance. Thus, a g ross l y o u t o f l i n e r e t u r n r a t e should f i r s t be adjusted t o f a l l i n the middle o f t he approp r ia te range presented i n Table 3-5.

Most a c t i v a t e d sludge p l a n t s w i t h f lows l e s s than 7,500 m3/d (2.0 mgd) a re designed conserva t i ve l y enough t h a t , a t wastewater f lows l e s s than design, gross adjustments t o b r i n g t h e sludge r e t u r n r a t e w i t h i n normal ranges o f t e n p rov ide s u f f i c i e n t l y improved c o n t r o l . Furthermore, most p l a n t s t h a t have been determined t o be Type 1 (major u n i t processes are adequate) are conserva t i ve l y enough loaded t h a t such gross adjustments may be a l l t h a t i s necessary f o r c u r r e n t 1 oadings. The appl i c a b i l i t y and r e s u l t s o f gross sludge r e t u r n adjustments a r e i l l u s t r a t e d by the f o l l o w i n g d iscuss ion:

+ bA

An a c t i v a t e d sludge p l a n t was exper ienc ing almost cont inuous problems w i t h sludge b u l k i n g i n t h e f i n a l c l a r i f i e r . Th is cont inued desp i te repeated e f f o r t s by the p l a n t super in tendent t o c o n t r o l the f i lamentous na ture o f t h e sludge. The super in tendent had c h l o r i n a t e d and dumped t h e e n t i r e a c t i v a t e d sludge mass t o p o l i s h i n g ponds tw ice and was now cons ide r ing adding c l a y as a s e t t l i n g a id .

93

Review of p l a n t operation indicated t h a t the return s ludge flow ra tes were about 150 percent of the raw wastewater flow rate. After a discussion of the advantages of a lower return rate, the superintendent reduced the return sludge rate to about 50 percent of the raw wastewater flow. Solids loss from the c l a r i f i e r s stopped i n about 3 hours.

T h i s gross return rate adjustment d i d not solve a l l of the p l a n t problems, b u t i t d i d significantly improve process control and performance. A t the higher return ra te , hydraulic loading to the f i n a l c l a r i f i e r had been 2.5 times the raw wastewater flow. After the adjustment, the hydraulic loading was reduced to 1 .5 times the raw wastewater flow. Although overflow rates were not affected, detention time i n the c l a r i f i e r f o r se t t l ing was increased by 67 percent and sol ids l o a d i n g t o the c l a r i f i e r was reduced by 40 percent. T h i s greatly enhanced the sol ids/l iquid separation function of the c l a r i f i e r .

Most Type 2 plants (major u n i t processes a re margina l ) or plants where gross return sludge flow adjustments do not produce the desired resu l t s will require a higher level of return sludge flow control, such as diurnal adjustments based on variations i n wastewater flow and sludge character t ha t occurs due to variations i n POTW l o a d i n g s over a 24-hour period.

Fine t u n i n g return sludge flow ra tes i s an area i n which several differing philosophies exis t within the technical c0mmunit.y. A complete explanation of each i s beyond the scope of this Handbook. The selection of a specific technique, and evaluation of the resu l t s , i s best l e f t to the ski l l and judgment- o f an experienced CCP f a c i l i t a t o r .

5.7.1.4 Aeration Basin DO Control

Oxygen levels i n an aeration basin can be used t o promote or hinder the growth rates of filamentous organisms i n the activated sludge process (8-111. DO control can therefore be used to promote the desired balance between f i l amentous and zoogleal microorganisms, control sludge character, and improve p l a n t performance.

In most activated sludge plants, regardless of size,. the greatest single use of energy is for aeration and mixing i n the aeration basin. The desire to cut energy and associated costs while m a i n t a i n i n g good performance makes the decision as to how much oxygen to use a c r i t i ca l one. Some guidelines and t e s t s t h a t have been used to aid i n making this decision i n other plants are presented below.

Oxygen supply i n an aeration basin can be thought of as satisfying two needs: oxygen demand and residual DO. Typically, these are sat isf ied without different ia t ion, b u t an understanding of b o t h may be helpful when evaluating oxygen needs. Oxygen demand is the mass of oxygen required to meet BOD and n i t r i f ica t ion demand and maintain a viable microorganism population. The required residual DO i s t h a t mass of oxygen needed t o provide the environment that produces good sludge character. The residual DO, which ex is t s i n an

94

a e r a t i o n bas in when the oxyqen demand i s s a t i s f i e d , v a r i e s w i t h the type of process. General ly, t h e h igher t h e organ ic l oad ing r a t e on t h e a c t i v a t e d sludge system, t h e h igher the res idua l DO w i l l be when the demand i s met. A general g u i d e l i n e f o r res idua l bu l k DO i s shown i n F igure 3-1. Higher oxygen r a t e s are, i n general, assoc iated w i t h a c t i v a t e d sludge systems t h a t have h igher organic loadings.

Operat ing experience has shown t h a t DO becomes a growth-1 i m i t i n g f a c t o r f o r zoogleal - type microorganisms be fo re becoming a l i m i t i n g f a c t o r f o r f i lamentous microorganisms. Do c o n t r o l a t l o w l e v e l s i n an a e r a t i o n bas in can t h e r e f o r e be used to apply pressure to s h i f t sludge c h a r a c t e r i s t i c s toward slower s e t t l i n g . Conversely, h igher DO l e v e l s can be used t o apply pressure f o r f a s t e r s e t t l ing.

I f a dec i s ion i s made t o lower DO by reducing aera t ion , proPer tes ing i s essen t ia l as i t i s a necess i ty t o recognize when too l i t t l e oxygen i s being t rans fe r red . Tests t h a t w i l l be most b e n e f i c i a l are res idua l DO measurements and oxygen uptake r a t e t e s t s (12). Residual DO measurements should be taken i n i t i a l l y a t several l o c a t i o n s throughout the ae ra t i on bas in and v e r i f i e d p e r i o d i c a l l y t o determine a sample p o i n t t h a t can be considered ''average.''

When determin ing res idua l DO, i t i s impor tan t t o take measurements several t imes du r ing the day t o be co inc iden t w i t h d i u r n a l f l o w v a r i a t i o n s , s ince res idua l DO demand t y p i c a l l y va r ies w i t h 1 oadings. Where 24-hour opera tor coverage o r in -bas in DO meters w i t h recorders a re ava i l ab le , d i u r n a l f l u c t u a t i o n s should be ob ta inab le as o f t e n as needed. I n o the r p l a n t s , a few "spec ia l DO tes ts ' ' i n the middle o f the n i g h t may be s u f f i c i e n t . The importance o f g e t t i n g DO readings f o r a l l major p l a n t l o a d c o n d i t i o n s i s t h a t anoxic , o r DO-def ic ient , c o n d i t i o n s promote the growth o f f i l amentous organisms lead ing t o bu l ky sludge character .

-_ . .

I n general , p l a n t s opera t ing a t low DO l e v e l s d u r i n g peak l o a d i n g may s t i l l p rov ide good t reatment i f cons iderab ly h ighe r W r e s i d u a l s e x i s t be fo re the day 's peak l oad ing i s received. For example, a p l a n t may operate very success fu l l y w i t h a DO o f 0.4-0.6 mg/l du r ing the day i f the morninq DO i s 1.0-1.5 mg/l. Th i s d a i l y f l u c t u a t i o n i n DO l e v e l s can produce t h e des i red mix o f zoogl ea1 and f i 1 amentous organi sms.

The oxygen uptake t e s t can a lso be used as a measure o f adequacy of oxygen t r a n s f e r (13). For example, i f t h e oxygen uptake t e s t i n d i c a t e s an oxygen demand s i g n i f i c a n t l y g r e a t e r than 0.65 k g O2/kg BOD5 removed p lus 0.1 k g 02/kg t o t a l sludge i n an a c t i v a t e d sludge system, the t e s t may be i n d i c a t i v e o f an inadequate oxygen supply. Th i s ana lys i s i s i l l u s t r a t e d by the fo l l ow ing .

An a c t i v a t e d sludge f a c i l i t y was removing approximately 240 k g (530 l b ) BODg/d w i t h a t o t a l sludge mass i n the ae ra t i on bas in and secondary c l a r i f i e r o f about 2,000 k g (4,500 l b ) . The c a l c u l a t e d oxygen demand i s [ (240 k g BODg/d) x (0.65 k g 0 /kg BOD 11 + [(2,0OO k g sludge) X

However, t h e measured oxygen uptake i n the 760 n? (200,000 ga l ) a e r a t i o n bas in was 30 mg/ l /hr , o r 550 k g (1,200 l b ) 02/d, o r 150 percent o f c a l c u l a t e d

(0.1 kg 02/kg sludge/d)] , o r 35% k g (7 8 3 l b ) 02/d.

95

oxygen demand. Th is i n d i c a t e d t h a t the r e a l i s t i c oxygen requirements are n o t be ing met w i t h t h e c u r r e n t res idua l DO o f 0.5-0.8 mg/l. Oxygen supply was increased, t u r b i d i t y o f the e f f l u e n t dropped, and the oxyqen demand measured by t h e oxygen uptake r a t e decreased t o 110 percent o f the c a l cu l a ted demand.

The above i l l u s t r a t e s t h e use of a successful t roub leshoot ing technique f o r i d e n t i f y i n g and c o r r e c t i n g a DO def ic iency . L i k e r e t u r n sludge c o n t r o l , t h e c a p a b i l i t y t o use DO c o n t r o l t o f i n e tune a c t i v a t e d sludge processes i s a f u n c t i o n o f the exper ience and techn ica l judgment o f the CCP f a c i l i t a t o r .

5.7.1.5 Process Control Pressure

As discussed i n Sec t ion 5.7.1.1, o v e r a l l ac t i va ted sludge p l a n t t reatment performance i s p r i m a r i l y a func t i on of t h e sludge character . Process c o n t r o l t e s t s and adjustments should be made w i t h the purpose o f ach iev ing chanqes i n t h e d i r e c t i o n o f des i rab le sludge character . The s p e c i f i c process c o n t r o l s

- - - d iscussed e a r l i e r (s ludge mass, s ludge re tu rns , and ae ra t i on bas in DO) are used t o apply a ' 'pressure" t o change sludge charac ter by changing t h e environment f o r the sludge mass.

When a change i n sludge charac ter i s desired, a combinat ion o f opera t iona l adjustments may be necessary t o p rov ide enough pressure t o achieve t h a t des i red range. For example, i f sludge s e t t l i n q has slowed t o an undesi rab le l e v e l and a wet weather season (which w i l l cause h igher average and peak c l a r i f i e r hydrau l i c load ings) i s approaching, i t would be advantageous t o expedi te e f f o r t s to increase t h e s e t t l i n g ra te . Simultaneous adjustments of several process c o n t r o l parameters coul d p rov ide more pressure i n the des i red d i r e c t i o n than making a change i n o n l y one c o n t r o l . I n general , a r a i s e i n the s ludge inventory , a r a i s e i n ae ra t i on bas in DO, and more f requent r e t u r n r a t e adjustments t o minimize sludge mass and sludge de ten t ion t ime i n t h e c l a r i f i e r would a l l be appropr ia te to achieve f a s t e r s e t t l i n g and b e t t e r c l a r i f i e r performance i n a minimal t ime under t h e h igher h y d r a u l i c l oad ing cond i t ions .

5.7.1.6 Time f o r B i o l o g i c a l System Response

When ad jus t i ng process c o n t r o l a t a c t i v a t e d sludge p lan ts , i t i s impor tan t to r e a l i z e t h a t changes i n sludge charac ter develop s lowly and t ime must be a l lowed f o r the b i o l o g i c a l system to respond to the pressures appl ied. Adjustments may change t h e environment of t h e a c t i v a t e d sludge very qu i ck l y , b u t a cons iderab ly l onger pe r iod o f t i m e may be requ i red be fore sludge charac ter changes t o r e f l e c t t h e new environment. For example, i f low DO i n a d i f f u s e d a i r ae ra t i on bas in i s be l i eved t o be a cause o f s l o w - s e t t l i n g sludqe, i t would be appropr ia te t o increase t h e oxygen t r a n s f e r by i nc reas ing blower output . Two changes should be monitored, one immediate and one long-term. Mixed l i q u o r DO measurements a few hours a f t e r t h e change as w e l l as t h e nex t

96

day should i n d i c a t e whether the increased blower output selected was s u f f i c i e n t t o change t h e environment (DO l e v e l ) i n t h e a e r a t i o n basin, b u t i t may take several weeks o f sludge s e t t l i n g t e s t s t o determine i f t h a t new environment a p p l i e d enough pressure t o cause the sludge to s e t t l e more r a p i d l y .

There i s a tendency t o r e t u r n t o s ta tus quo i f a des i red r e s u l t i s n o t achieved qu ick l y . I n the above example, a person us ing a t r i a l and e r r o r approach may decide a f t e r 3 days o f h ighe r DO t h a t a d d i t i o n a l a e r a t i o n was the wrong adjustment and a waste o f energy. However, a person d i r e c t i n g a CCP must have enough experience and conf idence t o hol d the changed environmental c o n d i t i o n s l ong enough t o produce t h e des i red r e s u l t . I f t h e des i red change i n sludge character has n o t s t a r t e d t o take p lace i n a l e n g t h o f t ime equal t o two o r t h r e e MCRTs, a d d i t i o n a l pressure should be appl ied. As a general re ference, a t ime equal to th ree t o f i v e MCRTs may be necessary t o produce changes i n sludge cha rac te r due t o process c o n t r o l adjustments.

An apprec ia t i on f o r t h e t ime r e q u i r e d f o r a b i o l o g i c a l system t o respond t o new pressures shauld be a major t r a i n i n g o b j e c t i v e o f t he CCP e f f o r t t o improve process c o n t r o l . Graphing mon i to r i ng r e s u l t s t o produce t rend c h a r t s can enhance t h i s apprec iat ion.

5.7.1.7 Ac t i va ted S1 udge Tes t i ng

A c t i v a t e d sludge p l a n t mon i to r i ng f o r e f f e c t i v e process c o n t r o l must i n c l u d e s l udge cha rac te r , s l udge mass, r e t u r n s l udge , and DO. Several references are a v a i l ab1 e f o r s e l e c t i n g t e s t s and t h e i r frequency f o r a c t i v a t e d s l udge p l a n t s (9 ) (14) (15).

The t e s t s and schedule shown i n Table 5-2, developed f o r a 190 m3/d (50,000 gpd) p l a n t ope ra t i ng under h i g h l y v a r i a b l e c o n d i t i o n s due t o d r a s t i c c l i m a t e changes and wide seasonal popu la t i on f l u c t u a t i o n s , are app l i cab le t o many small a c t i v a t e d sludge p lan ts . The concept of p r o v i d i n g two d i f f e r e n t frequency schedules i s a compromise between t h e des i rab le h igher f requencies and the minimum operator t ime t y p i c a l l y a l l o c a t e d t o t h i s f u n c t i o n i n small f a c i l i t i e s . Under normal ope ra t i ng cond i t i ons , w i t h l i t t l e s t r e s s on t h e processes, t h e ' ' rou t ine" frequency i s adequate. When the system i s under s t ress, t h e ' l c r i t i c a l " frequency i s appropr iate. This occurs d u r i n g t r a n s i t i o n s t o h igher loadings, d u r i n g peak seasonal populat ions, and can occur unp red ic tab l y i f bu lky sludge cha rac te r develops o r equipment f a i l s .

Even i n small a c t i v a t e d sludqe p l a n t s a concentrated process c o n t r o l e f f o r t based on r e l i a b l e t e s t i n g and understanding o f process fundamentals i s necessary, as i l l u s t r a t e d by the p r cess c o n t r o l t e s t i n g schedule and

p l a n t and shown i n F igu re 5-7. (Note: When t h e CCP was i n i t i a t e d , mon i to r i ng of a e r a t i o n bas in DO was n o t inc luded because the t e s t i n g c a p a b i l i t y was n o t a v a i l a b l e a t t h e time.)

reco rd ing sheet developed f o r a 950 m 9 / d (0.25 mgd) c o n t a c t s t a b i l i z a t i o n

97

TABLE 5-2

PROCESS CONTROL M O N I T O R I N G AT A SMALL ACT1 VATED SLUDGE PLANT

Test , Parameter, o r Eva1 u a t i on

F1 ow Equal i z a t i o n :

Water Level Pump S e t t i n g vs. D a i l y Flow, DO

Frequency Rout ine c r i t i c a l *

D a i l y 2/day 3lweek D a i l y

Ac t i va ted S1 udge:

Contro l Tests 3/week D a i l y Cen t r i f uge Spins ( A e r a t i o n Tank Conc./ Return Sludge Conc. /C la r i f ie r Core Sample Conc. 1, S e t t l eometer Test, Depth t o B1 anket, Aera t ion Basin DO

c- -

Contro l Ca lcu la t i ons 3/week D a i l y To ta l Sludge Mass, Aera tor Sludge Mass, C1 a r i f i e r S1 udge Mass, Return S1 udge Percentage, S1 udge D i s t r i b u t i o n Rat io , C l a r i f i e r So l ids Loading, MCRT

Contro l P1 o t s 3lweek D a i l y Graph 1: S e t t l i n g Resul ts, Return Sludge

Graph 2: Tota l Sludge Mass (Aera to r and Conc., MCRT, DO, Aerator Conc.

C1 a r i f i e r ) , Wasted S1 udge Mass

Wasting Volume, Concentrat ion, Mass

3/week D a i l y

D i gester :

DO, Concentrat ion, Temperature, pH Weekly Zlweek Waste Ac t i va ted S1 udge, Digested S1 udge Monthly Zlmonth

Vol a t i l e Sol i d s Percentage, Vol a t i l e So l i ds Reduction

Ch lor ine Residual : 5lweek D a i l y

* " C r i t i c a l " r e f e r s t o per iods o f t r a n s i t i o n t o h igher load ings and du r ing peak load ings and per iods o f s t ressed operat ion, i.e., bu l ky sludge, process ou t of serv ice, o r ma jor change i n process c o n t r o l .

98

FIGURE 5-7

PROCESS CONTROL TESTING AT A 950 m3/d CONTACT S T A B I L I Z A T I O N POTW*

Mo/DAY /Y R DAY OF WEEK

CENTRIFUGE TEST CTC RTC RSC Dc

DSU

SLUDGE DTB

RSFP c_ . .

SLUDGE CTSU RTSU csu TSU

SLUDGE

BLANKET TEST

INVENTORY

SETTLIW TEST

0 m i n 5 m i n 30 m i n 60 m i n

SLUDGE WASTING

centimeters cubic m e t e r s WSC WSU

SLUDGE HAULING I oads cubic m e t e r s sc su

UEEKLY CALCULATIWS

Week of through

ssv ssc bT v + 1 +

I

Avg. Waste = T o t a l WSU t 7 =

S ludge Age = Avg. TSU i Avg. Waste = i - -

Week I y Average

** Weekly Toti, I

Avg. F l o v ma/d

INFLUENT EFFLUENT BODS TSS

*Acronyms for t e s t parameters are defined on the following page.

99

CTC

RTC

RSC

DC

DSU

DTB

RSFP

CTSU

RTSU

csu

TSU

ssv

ssc

wsc

wsu

sc

su

FIGURE 5-7 (cont inued)

ACRONYMS FOR TEST PARAMETERS

Contact Tank Concentrat ion

Reaerat ion Tank Concentrat ion

Return Sludge Concentrat ion

D iges te r Sludge Concentrat ion

D iges te r Sludge U n i t s (mass o f sludge)

Depth t o (Sludge) Blanket ( i n f i n a l c l a r i f i e r )

Return Sludge Flow Percentage ( o f wastewater f l ow)

Contact Tank 'Sludge U n i t s (mass o f sludge)

Reaerat ion Tank Sludge U n i t s (mass o f sludge)

C l a r i f i e r Sludge U n i t s (mass o f sludge)

To ta l Sludge U n i t s (mass o f sludge i n con tac t tank, r e a e r a t i o n tank, and c l a r i f i e r )

S e t t l e d Sludge Volume (volume o f s e t t l e d sludge i n a se t t l eomete r j a r a f t e r t h e i n d i c a t e d number o f minutes)

S e t t l e d Sludge' Concentrat ion ( c a l c u l a t e d concen t ra t i on o f sludge i n t h e s e t t l e d sludge volume i n t h e se t t l eomete r j a r a f t e r t h e i n d i c a t e d number o f minutes)

Waste Sludge Concentrat ion

Waste Sludge U n i t s (mass o f sludge wasted)

Sludge Concentrat ion

Sludge U n i t s (mass o f d igested sludge hauled out )

100

Larger a c t i v a t e d sludge POTWs r e q u i r e t h a t the same parameters be monitored, b u t these p l a n t s are o f ten designed l e s s conserva t i ve l y and t h e r e f o r e r e q u i r e m r e f requent mon i to r i ng and process adjustments. Fo r example, a t a 21,000

conducted once per 8-hour s h i f t , 7 days per week. A t the con tac t s t a b i l i z a t i o n p l a n t mentioned above, sludge s e t t l i n g and mass c o n t r o l t e s t s were conducted on ly once per day, 5 days per week.

m 3 / d (5.5 mgd) a c t i v a t e d sludge p l a n t , s e t t l i n g and mass c o n t r o l t e s t s were

To improve process c o n t r o l , a1 1 ac t i va ted sludge p l a n t s should i nc lude mon i to r i ng f o r a t l e a s t t h e fo l l ow ing :

- S1 udge s e t t l i n g - To ta l s ludge mass c o n t r o l - Sludge wast ing - Return sludge concent ra t ion and f l o w c o n t r o l - Aera t ion bas in DO c o n t r o l

Appendix I conta ins an example process c o n t r o l d a i l y data sheet t h a t has proven to be usefu l i n mon i to r i ng a c t i v a t e d sludge POTWs. However, the s p e c i f i c t e s t s and sampling frequency must be se lected f o r each i n d i v i d u a l ”.

5.7.2 F ixed F i l m Process Contro l

The perforniance o f f i x e d f i l m ( t r i c k l i n g f i l t e r and RBC) POTWs i s n o t as c r i t i c a l l y a f f e c t e d by process c o n t r o l adjustments as suspended growth f a c i l i t i e s (1)(3). There a re o n l y a l i m i t e d number of process c o n t r o l s i n f i x e d f i l m systems t h a t can be op t im ized by a CCP, and t h e r e s u l t i n g improvement i n e f f l u e n t q u a l i t y i s accord ing ly l e s s . Two areas o f f i x e d f i l m process c o n t r o l t h a t can be op t im ized are r e t u r n process stream load ings and c l a r i f i e r performance.

5.7.2.1 Reducing Return Process Stream Loadings

The CCP f a c i l i t a t o r should s t r i v e to reduce the organic l oad ing returned through t h e p l a n t from anaerobic d i g e s t i o n and from sludge dewater ing operat ions. D i sposal o f a1 1 d iges te r supernatant w i t h the d igested s l udge can s i g n i f i c a n t l y reduce p l a n t o rgan ic loadings. Th is has been implemented most f r e q u e n t l y i n smal ler POTWs where sludge disposal i s by l i q u i d haul t o nearby farmland. Another way to achieve organ ic l o a d reduc t i on i s by f i l t e r i n g t h e d i g e s t e r supernatant through a d r y i n g bed.

When dewater ing d iges te r sludge w i t h a b e l t press, vacuum f i l t e r , o r c e n t r i f u g e , chemical dosages are o f t e n op t im ized t o lower costs. I f a low, o r re1 a t i v e l y 1 ow, s o l i d s capture i s be ing accompl ished, increased chemical usage t o increase capture and reduce r e t u r n f l o w through t h e p l a n t should be considered.

101

Since l a n d disposal of anaerobic digester supernatant or increased chemical usage t o improve dewatering capture can resu l t i n s ignificantly higher operating costs , a short-term (e.g., one m o n t h ) t r ial period shou ld be conducted before advocating a permanent change i n these controls.

5 .7 .2 .2 Optimizing C1 a r i f i e r Operation

O p t i m i z i n g primary c l a r i f i e r process control wi l l decrease organic l o a d i n g on subsequent fixed f i lm processes. Optimizing secondary c l a r i f i e r process control will improve overall organic removal for any fixed film system. Organic removals i n b o t h primary and secondary c l a r i f i e r s can be optimized by minimizing overflow rates and controlling sludge quantit ies i n the c l a r i f i e r s .

Overflow rates can be minimized by eliminating any unnecessary flow through the c l a r i f i e r s . The most common situation t h a t can be addressed by process control occurs when t r ickl ing f i l t e r recycle also goes through ei ther the primary or secondary c l a r i f i e r . A t normal organic loadings associated w i t h domestic secondary treatment f a c i l i t i e s , recirculation does not provide significantly improved organic removals i n fixed f i lm processes ( 1 6 ) . This i s especially true i f the recirculation resu l t s i n increased c l a r i f i e r overflow rates . If recirculation does i n fac t increase soluble BOD removal i n the fixed fi lm process and the existing recirculation flow pattern i s t h r o u g h the primary or secondary c l a r i f i e r , a f a c i l i t y modification to provide recirculation only through the fixed film process may be ju s t i f i ed (see Section 5 .4 ) .

- - .

Keeping sludge blankets and sludge detention times low i n both primary and secondary c l a r i f i e r s also tends to optimize organic removals. T h i s can often be accomplished by increasing sludge pumping, b u t must not be carried to the extreme tha t removed sludge i s so t h i n t ha t i t adversely affects sludge treatment processes. Experience and judgment of the CCP f a c i l i t a t o r must be used t o achieve the best compromise.

5.7.2.3 Fixed F i l m Testing

Process control moni tor ing for fixed film f a c i l i t i e s i s generally simpler than for suspended growth systems. I t i s normally comprised o f process loading and performance monitor ing. The performance of the primary c l a r i f i e r , fixed film reactor, and f ina l c l a r i f i e r should be monitored on a routine basis. Fixed film reactor performance can best be monitored by measuring soluble BOD5 removals. The soluble BOD t e s t more direct ly addresses the primary function of the biological reactor, to convert dissolved and colloidal organics to microorganism sol id s . Measuring soluble B O D 5 across the fixed film reactor monitors th i s conversion process.

An example process control summary sheet developed for a 7,500 d / d (2.0 mgd) R B C POTW d u r i n g a CCP i s presented i n Appendix J .

1 02

5.7.3 ABF Process Contro l

The ABF design con ta ins elements o f bo th suspended growth and f i x e d f i l m f a c i l i t i e s as does ABF process c o n t r o l . S1 udge charac ter ( s e t t l i n g ra tes , compaction c a p a b i l i t y , appearance, e tc . ) i s more l i k e t h a t o f f i x e d f i l m s ludge i n t h a t wide f l u c t u a t i o n s a re n o t common and are n o t as dependent on process c o n t r o l adjustments. Consequently , o v e r a l l sludge r e t u r n r a t e s and d i u r n a l adjustments a re n o t as c r i t i c a l i n the ABF system as i n a c t i v a t e d sludge. The same i s t r u e f o r ae ra t i on bas in DO. DO must be prov ided t o meet the demand i n an ABF system w i thou t spec ia l cons ide ra t i on f o r the res idua l DO and i t s e f f e c t on sludge cha rac te r (17). A DO res idua l o f 2-3 mg/l i s usua l l y s u f f i c i e n t .

The process c o n t r o l i n an ABF system t h a t i s s i m i l a r t o an a c t i v a t e d sludge system and s l i g h t l y more suscept ib le to problems i s suspended growth sludge mass c o n t r o l . Mass c o n t r o l i s very c r i t i c a l i n an ABF system because a l a r g e f r a c t i o n o f t h e mass, u s u a l l y one-quarter t o one-hal f , i s wasted d a i l y . Any e r r o r i n wast ing has a s i g n i f i c a n t e f f e c t because the MCRT i s u s u a l l y o n l y 2-4 days.

Process c o n t r o l parameters mon Appendix K.

c- -

t o red n two ABF POTWs are presented i n

5.8 Example CCP

An example CCP i s d i f f i c u l t to present because many o f the performance- 1 i m i t i n g f a c t o r s are addressed through t r a i n i n g , in te rpersonne l r e l a t i o n s h i p s , weekly data review, phone consu l ta t i ons , and o ther a c t i v i t i e s conducted over a l ong pe r iod o f time. These a c t i v i t i e s do n o t l e n d themselves r e a d i l y to an abbrev iated d iscuss ion (18) . As such, an overview o f a CCP i s presented based on t h e example CPE presented i n Sec t ion 3.9.

5.8.1 Addressing Performance-Limi t i n g Fac tors

The most ser ious performance-1 i m i t i n g f a c t o r s i d e n t i f i e d i n t h e CPE were process con t ro l o r ien ted . The major emphasis, t he re fo re , o f the i n i t i a l p o r t i o n o f t h e CCP was d i r e c t e d a t improv ing p l a n t opera t ions (process c o n t r o l 1.

1. Operat ion (Process Contro l

- Process con t ro l t e s t i n g t o mon i to r sludge s e t t l i n g , s ludge mass, s l udge wast ing, s l udge r e t u r n concen t ra t i on and f low, and a e r a t i o n bas in DO was i n i t i a t e d us ing the gu ide l i nes i n Table 5-2.

- A process c o n t r o l summary was developed and process c o n t r o l c a l c u l a t i o n s were implemented as shown i n Appendix I .

103

- Trend graphs were i n i t i a t e d t o mon i to r a c t i v a t e d sludge mass inventory and wasting, and a c t i v a t e d sludge character and r e t u r n c onc e n t r a ti o n s .

- On-the-job t r a i n i n g was provided i n the areas o f b i o l o g i c a l t reatment fundamentals and s p e c i f i c process c o n t r o l tasks and m o n i t o r i n g requirements (see Sec t ion 5.7)

- E f f l u e n t TSS was monitored c l o s e l y t o d e t e c t excess sludge losses and p rov ide j u s t i f i c a t i o n f o r adequate s l udge disposal capabi l i ty.

Resul ts o f t h e improved process c o n t r o l a c t i v i t i e s l e d t o the f o l l o w i n g sequence o f events:

- Operat ional t e s t s showed t h a t actua l sludge p roduc t i on averaged 0.81 kg TSS produced/kg BOD5 removed. It was est imated t h a t t h e amount o f sludge produced t h a t was discharged as e f f l uent SS woul d decrease from 40 percent t o 10 percent i f adequate sludge d isposal f a c i l i t i e s were a v a i l ab le and used p roper l y . New s l udge wast ing requirements were 0.73 kg TSS/kg BOD5 removed. This actual va lue was h ighe r than the p r o j e c t e d sludge p roduc t i on o f 0.65 k g TSS/kg BOD5 removed used i n t h e CPE example, f u r t h e r aggravat ing t h e c a p a c i t y 1 i m i t a t i o n o f the anaerobic d iges te r .

c- .

- POTW a d m i n i s t r a t o r s were presented w i t h the sludge p roduc t i on values and e x i s t i n g p l a n t c a p a b i l i t i e s by us ing the f o l l o w i n g explanat ion: "Your POTW t r e a t s about 350 m i l l i o n q a l l o n s o f wastewater a year which r e s u l t s i n about 5.5 m i l l i o n g a l l o n s o f sludge. This sludge must be disposed o f proper ly . The e x i s t i n g aerobic d i g e s t e r i s too small t o handle t h e t o t a l sludge produced. This one d e f i c i e n c y negates a s i g n i f i c a n t p o r t i o n o f the p o l l u t i o n c o n t r o l a l ready accomplished i n t h e r e s t o f t he p lan t . I f you want t o b r i n g your p l a n t i n t o compliance and ob ta in f u l l b e n e f i t from t h e r e s t o f t h e p l a n t , a d d i t i o n a l acceptable sludge hand l i ng c a p a c i t y w i l l have to be provided."

- A f t e r cons ide r ing var ious opt ions, i n c l u d i n g cons t ruc t i on , i t was decided t o u t i l i z e a c o n t r a c t hauler t o d i s ose o f l i q u i d sludge i n a nearby 1 arge POTW a t a charge o f $15.85/m 3 ($0.06/gal).

- The f i r s t month of c o n t r a c t . hau l i ng r e s u l t e d i n a supplemental sludge disposal c o s t o f $4,500 and a l l i nvo l ved be l i eved a s i g n i f i c a n t e f f o r t t o reduce t h i s c o s t was j u s t i f i e d . An e f f o r t was made to increase t h e concen t ra t i on o f t he sludge fed t o t h e d i g e s t e r by th i cken ing the sludge i n an o l d c l a r i f i e r a v a i l a b l e on the p l a n t s i t e . Polymer was used t o a i d i n t h e sludge th i cken ing . A f t e r several t r i a l t e s t s , a polymer was found t h a t s i g n i f i c a n t l y improved waste s l udge concentrat ions from t h e " t h i c k e n i n g tank .Ii The concen t ra t i on fed t o the d i g e s t e r was increased about 250 percent by adding 20-25 l b polymer/ton sludge so l i ds . The n e t e f f e c t was t o decrease supplemental sludge disposal c o s t by 56 percent from t h e $4,50O/month i n i t i a l l y incurred.

104

2. Design

- M ino r p i p i n g changes and a polymer feed system had t o be provided t o use the a v a i l a b l e tankage a t t h e p l a n t as a " th ickener . " Major des ign changes, such as e n l a r g i n g the aerobic d iges te r , were avoided as a r e s u l t o f t h e C C P e f f o r t s .

3. Maintenance

- Suggested p reven t i ve maintenance forms ( s i m i l a r t o those i n Appendix G) were provided the p l a n t super intendent d u r i n g the CCP. However, t h e l a c k o f a documented p reven t i ve maintenance program had n o t been a s i g n i f i c a n t performance-1 i m i t i n g problem be fo re the CCP was implemented and d i d n o t become s i g n i f i c a n t d u r i n q t h e CCP. Consequently, emphasis was p l aced on f a c t o r s more d i r e c t l y re1 ated t o performance.

4. Admini s t r a t i o n

c- - - Admin i s t ra to rs ' f a m i l i a r i t y w i t h p l a n t needs and t h e i r a b i l i t y t o make appropr ia te dec is ions regard ing the p l a n t was increased du r ing t h e CCP by e x p l a i n i n g process fundamentals a t t he p l a n t , p r o v i d i n q o r a l s ta tus repo r t s , and i n v o l v i n g them i n c o r r e c t i o n o f the sludge c a p a c i t y def ic iency.

5.8.2 P1 a n t Performance

P1 ant performance was improved d r a m a t i c a l l y by implementation o f t h e CCP. r esul t s are summari zed bel ow:

The

E f f l uent 3- TSS E f f l uent

ms/ 1 mg/l

Before CCP Rep0 r t e d 14 Estimated Actual 44

1 5 75

A f t e r CCP Actual 14 17

The repor ted values p r i o r t o t h e CCP were c o l l e c t e d o n l y d u r i n g per iods when the c l a r i f i e r s were n o t b u l k i n g sludge. The est imated actual e f f l u e n t q u a l i t y was p r o j e c t e d by comparing sludge wasted p r i o r t o t h e CCP w i t h sludge wasted a f t e r the CCP was i n i t i a t e d . The d i f f e r e n c e i n these values was p ro jec ted t o have been c o n s i s t e n t l y l o s t from t h e system i n t h e p l a n t e f f l u e n t d u r i n g pe r iods o f b u l k i n g sludge. Actual r e s u l t s a r e based on proper t e s t i n g and represent a t r u e p i c t u r e o f p l a n t performance a f t e r t h e CCP was i n i t i a t e d .

105

5.8.3 C C P c o s t s

The c o s t s f o r the example C P E and CCP descr ibed i n Sec t ions 3.9 and 5.8 a r e s u"ar i zed bel ow :

C P E Consul t a n t C C P Consul t a n t Test Equipment Polymer Addition Equipment S1 udge D i sposal Polymer

Total

$ 3,500 (one-time) 12,000 (one- t ime )

700 (one- time) 550 (one-t ime)

26,500 ( annual 1 2,500 ( annual )

$45,750 ( f i r s t y e a r ) $29,000 (ongoing annual c o s t s )

5.8.4 Summary

c- . T h i s example i l l u s t r a t e s several important p o i n t s of the CCP approach and includes several problems and a s soc ia t ed s o l u t i o n s t h a t occur frequently d u r i n g CCP implementation. These are :

- T h e primary o b j e c t i v e of a C C P i s a t t a i n i n g adequate performance. The second i s minimizing c o s t s w i t h i n the framework of adequate t r ea tmen t .

- Some po ten t i a l performance-l imit ing f a c t o r s ident i f ied d u r i n g a CPE a r e l a t e r found t o be i n c o r r e c t o r less s i g n i f i c a n t when a c t u a l l y e l i m i n a t i n g problems w i t h a CCP. T h i s was true of the digester design l i m i t a t i o n s i n this p lan t .

- The degree of admin i s t r a t ive suppor t i s sometimes d i f f i c u l t t o a s s e s s d u r i n g a CPE b u t o f t e n becomes a major concern d u r i n g a CCP. T h i s was true when the admin i s t r a to r s were faced w i t h suppor t ing dramatical l y increased sl udge hand1 i n g c o s t s i n the example CCP.

- A Type 2 POTW was brought i n t o compliance wi thout a major p l a n t upgrade.

5.9 CCP Results

The success o f conduct ing CCP a c t i v i t i e s can o f t e n be measured by a v a r i e t y of parameters , such a s improved ope ra to r capabi l i t y , c o s t savings, improved maintenance, etc. However, the true success of a CCP should be documented improved performance to the degree t h a t the p l a n t has achieved compliance. Given th i s measure, the results of a successful C C P e f f o r t should be e a s i l y dep ic t ed i n graphical form. Results from an ac tua l CCP a r e presented i n Figure 5-8. I t i s d e s i r a b l e t o present C C P results i n this format.

106

FORM 0-3 (continued)

DESIGN DATA

B. UNIT PROCESSES:

Prel iminary Treatment I

Comminutor:

Name

Mod e 1 Horsepower

Within Bui lding? Heated? Maintenance:

Comments :

Gri t Remova 1 :

Descript lon o f Un i t :

Grit Volume:

Normal CU yd/d x 0.75 = m3 /d

Peak CU yd/d x 0.75 = m3/d

Disposal o f Grl t :

Comnents:

156

FORM D-3 (cont inued)

DESIGN DATA

B. U N I T PROCESSES:

Pre l im inarv Treatment

Mechanical Bar Screen:

Name Model Horsepower

Bar Sc reen W i d t h i nch x 2 .54 = cm

Bar Spacing inch, O.C. x 2 .54 = cm, O.C.

W i th in Bu i l d ing? Heated 1

Descr ip t i on o f Operation:

Hand-Cleaned Bar Screen: Bar Screen Width i nch x 2.54 = cm

Bar Spacing inch, O.C. x 2.54 = cm, O.C.

Cleaning Frequency

Wi th in Bu i l d ing? Heated? Screenings Volume:

Normal cu yd/d x 0.75 = m3/d

Peak cu yd/d x 0.75 = m3/d

Screening Disposal :

Comnents :

155

FORM 0-3 (cont inued)

DESIGN DATA

8. UNIT PROCESSES:

Flow Stream Pumped

Comments capac i ty

Pumpi ng (Complete as many forms

No. o f Type Pumps Name

( f l o w c o n t r o l , s u i t a b l l i t y o f check dur ing CPE, e t c . ) :

as necessary)

Model HP Capaci ty Head

i n s t a l l e d equipment, r e s u l t s o f

Comments :

Comnents :

154

P

FORM D-3 (cont inued)

DESIGN DATA

8. UNIT PROCESSES:

Flow Measurement

(Form f o r each f l o w measuring device)

Flow Stream Measured

Contro l Sect ion:

Type and Size

Locat ion

Comments (opera t iona l problems, maintenance problems, unique features, p revent ive maintenance procedures, etc.) :

Recorder:

Name Mod e 1 F1 ow Range

C a l i b r a t i o n Frequency

Date o f Last C a l i b r a t i o n

Loca t i on

To ta l i zer

Comnents (opera t ion and design problems, unique features, e tc . ) :

Accuracy Check During CPE:

Method o f Check:

~ Resul ts:

153

I’

FORM 0-3

DESIGN DATA

A. INFLUENT CHARACTERISTICS:

Average D a i l y Flow:

Maximum Monthly Flow:

Maximum Hour ly Flow:

Average D a i l y BOD5:

Average D a l l y TSS:

I n f i l t r a t i o n / I n f l o w :

Seasonal Va r ia t i ons :

Major I n d u s t r i a l Wastes:

C o l l e c t i o n System:

Design mgd x 3,785 = m3 /d Current mgd x 3,785 = m3/d

Design mgd x 3,785 = m3 /d

Current mgd x 3,785 = m3/d

Design mgd x 3,785 = m3 /d

Current mgd x 3,785 = m3 /d

Des i gn l b x 0.454 = kg

Current l b x 0.454 = kg

Des i gn l b x 0.454 = kg

Current l b x 0.454 = kg

Comnen t s :

152

FORM D-2 (cont inued)

ADMINISTRATION DATA

3 . ENERGY CONSUMPTION:

N a t u r a l Gas

Source o f

U n i t Cost

Mon t h/Yea r

I n f o r m a t i o n

( A t t a c h r a t e schedule i f a v a i l a b l e )

Days i n B i l l i n g Per iod

Usage ( c u f t ) c o s t

T o t a l

Average

Miscel laneous (Fue l O i l . D i g e s t e r Gas. e t c . )

151

FORM D-2 (cont inued)

ADMINISTRATION DATA

I. ENERGY CONSUMPTION:

E l e c t r i c i ty

Source o f In fo rmat ion

Base Cost g?/kWh (At tach r a t e schedule i f a v a i l a b l e )

Energy Usage 1 kWh)

Days i n B i 11 i n g Per iod

Energy Demand cos t

F1 ow JMnal)

Month/ Year

ECA* cos t

- -

Base Tota l - cost cos t

--

Tota l

To ta l Flow (Mgal)

kWh/d kWh/.1,000 ga l x 0.264 = $ I d

kWh/$

- C/l ,OOO ga l x 0.264 = I / $

*ECA = Energy Cost Adjustment, which i s t he pass-through cos t al lowed t o p u b l i c se rv i ce companies f o r increased f u e l cos t t o generate e l e c t r i c i t y .

150

FORM D-2 (cont inued)

ADMINISTRATION DATA

- Personnel

o W l t h l n range o f o t h e r p l a n t s ?

o Al lows adequate t ime?

o Mot ivat ion, pay, superv is ion, worklng cond l t lons?

o P r o d u c t l v i t y ?

o Turnover?

- Involvement

o V l s l t s t o t reatment p l a n t ?

o Awareness o f f a c i l i t y performance?

o Request s t a t u s r e p o r t s (performance and cos t - re la ted)?

o F a m i l i a r i t y w l t h p l a n t needs?

A t t l tude Assessment:

Exce l len t : R e l l a b i l l t y provides adequate t reatment a t lowest reasonable cos t .

Normal : Provide as good a t reatment as p o s s i b l e w l t h the money a v a i l a b l e .

Poor: Spend as l l t t l e as poss ib le w l t h no c o r r e l a t i o n made t o achiev ing p l a n t performance.

149

FORM D-2 (cont inued)

ADMINISTRATION DATA

H. POLICY, SUPPORT, AND ATTITUDE:

Owner Respons ib i l i t y : - A t t i t u d e toward s t a f f ?

- A t t i t u d e toward regu la to ry agency?

- Se l f -sus ta ln lng f a c i l i t y a t t i t u d e ?

- A t t i t u d e toward consul tants?

- Future p lans? - P o l i c i e s ?

Performance Goal: - I s p l a n t i n compliance?

o I f yes, what 's making I t t h a t way?

o I f no, why no t? - I s regu la to ry pressure f e l t f o r performance?

- What a re performance requirements?

Admin i s t ra t i ve Support:

- Budget

o Wi th in range o f o the r p lan ts?

o Covers c a p i t a l improvements?

o *Drained* t o general fund? o Unnecessary expend1 tu res?

o S u f f l c i e n t ?

148

FORM D-2 (continued)

ADMINISTRATION DATA

G. DISCUSSION OF EXPENDITURES:

Budaet for: Dollar Amount Percent of Total

Salaries (incl. fringes) $

Utilities Trai ni ng Other

Operations Subtotal $

Capital Outlay (incl, bond debt retirement and capital replacement)

Total 100

Operational Cost Per Thousand Gallons (Operations Subtotal $ i Yearly Flow)

$ i Mgal/yr i 10 = //1,000 gal x 0.264 = $/In3

Approximate Annual Cost Per Tap (Total $ i No. o f Taps)

$ i taps = $ /tap

Comnents :

147

F. REVENUE:

TyDe o f TaD

Other Sources o f Revenue:

Comnents :

FORM 0-2 (continued)

ADMINISTRATION DATA

TaD Fee User Fee

146

n

FORM 0-2 (continued)

ADMINISTRATION DATA

E. BOND RETIREMENT:

I n t e r e s t pond TYDe Year Issued Duration Rate Pro jec t Financed

Conments :

145

FORM D-2 (cont inued)

ADMINISTRATION DATA

D . PLANT BUDGET ( A t t a c h copy o f a c t u a l budget i f a v a i l a b l e ) :

(Budget Year 1

144

FORM D-2 (cont inued)

ADMINISTRATION DATA

B . PLANT PERSONNEL:

Personnel C l a s s i f i c a t i o n

C .

- No.

IT

T i t l e

VE

F r a c t i o n o f Time Spent C e r t i f i c a t i o n Pay Sca le w i t h Wastewater Treatment

GE:

Weekdays

Weekends & Hol idays

143

FORM 0-2

ADMINISTRATION DATA

A . ORGANIZATION:

Governlng Body

Scheduled Meet ing Dates and Times

Author1 t y and Responsi b i 11 t y :

Members' Names (notes on l e a d e r s h i p , funding preferences, knowledge o f p l a n t needs, e t c . ) :

Chain o f Command ( f rom governing body through major i n - p l a n t deci sionmakers) :

142

i

FORM D-1 (cont 1 nued)

GENERAL POTW I N F O R M A T I O N

I . PLANT FLOW DIAGRAH:

141

FORM 0-1 (cont lnued)

GENERAL POTW INFORMATION

D. MAJOR PROCESS TYPE

E. DESIGN FLOW:

Present Deslgn Flow mgd x 3,785 = m3/d

F. UPGRADING AND/OR EXPANSION HISTORY ( o r i g i n a l cons t ruc t ion , date completed, p l a n t upgrade, date completed):

G. PROPOSED UPGRADES:

H. S E R V I C E AREA:

Number o f Taps

General Descr lp t lon ( r e s l d e n t l a l , approx lhate commercial and/or I n d u s t r i a l c o n t r i b u t i o n , e tc . ) :

140

FORM D-1 (cont inued)

GENERAL POTW INFORMATION

C. PERMIT INFORMATION:

P lan t C l a s s i f i c a t i o n Assigned by S ta te Discharge Permit Requirements f rom Permit Number

Date Permit Issued

Date Permit Expires

E f f l u e n t L i m i t s and Mon i to r ing Requirements:

Parame t e r

Flow, mgd

BODS, mg/l

TSS, mg/l

Fecal Col i form, no./100 m l

Ch lo r ine Residual, mg/l

pH, u n i t s

Ammonia, mg/l

O i l b Grease,

Others

mg/l

Maxi mum Max 1 mum Month1 y Weekly Average Averase

Mon i to r ing Sample Frequency TY Pe Reaui red Reaui red

Compl lance Schedule:

139

FORM 0-1

GENERAL POTW INFORMATION

A. NAME AND LOCATION:

Name o f F a c i l i t y

Type o f F a c i l i t y

Owner

Admin i s t ra t i ve O f f i ce :

Mal 1 i n g Address

Primary Contact T i t l e Telephone No.

Treatment P lant :

Mai 1 i n g Address

Primary Contact

T i t l e Telephone No.

D i rec t i ons t o P lan t

B. R E C E I V I N G STREAM AND CLASSIFICATION:

Rece 1 v i ng Water

T r i b u t a r y t o

Major R i ve r Bas 1 n

gomnents :

1 38

APPENDIX D

DATA COLLECTION FORMS USED I N CONDUCTING CPEs

- Form

D-1 0-2 D-3 0-4 D-5 D-6

- T i t l e

General POW Information Admi n i s t r a t 1 on Data Design Data Operations Data Maintenance Data Performance Data

137

supplemental w in ter sludge disposal . Estimated costs f o r conducting a CCP a t Spr ingf ie ld a re l i s t e d below:

CCP F a c i l i t a t o r $ 9,500 (one-time)

Minor Modl f icat ions 1.000 (one-time) Lab Equipment 400 (one-time) Supp 1 emen t a 1 S 1 udge D i s posa 1

c i t y costs

18.000 (annual) $1 9,400

Tota l CCP Costs $28,900

136

f a m i l i a r i t y i n the areas o f t reatment fundamentals, opera t ion and maintenance requirements, funding needs, and sa fe ty concerns i s needed.

7. Process C o n t r o l l a b i l i t y (Desinn). E x i s t i n g f l o w - s p l i t t i n g c a p a b i l i t y t o the RBCs i s inadequate. Cor rec t ion o f t h i s de f i c iency w i l l l i k e l y r e q u i r e minor design mod i f i ca t i ons .

8. U l t ima te Sludse DisDosal (Desisn). E x i s t i n g d r y i n g beds a re inadequate f o r needed year-round sludge d isposa l . Add i t i ona l beds may be a long-term so lu t i on . L i q u i d sludge haul t o farmland may be a workable i n t e r i m so lu t i on . Documentation f o r t he need and a d m i n i s t r a t i v e t r a i n i n g are necessary.

9. Performance Moni t o r i nn (ODeration). Improved sampling t o represent ac tua l performance and f l o w discharge i s needed. Onsi te t r a i n i n g coupled w i t h a d m i n i s t r a t i v e support t o e l i m i n a t e problems are requi red.

10. I n s u f f i c i e n t Fundi nq (Admin is t ra t ion) . Admi n 1 s t r a t i ve u n f a m i l i a r i t y w i t h p l a n t needs, inadequate techn ica l guidance, and improper past opera t ion and maintenance have a l l l e d t o i n s u f f i c i e n t funding. Admin i s t ra t i ve t r a i n i n g i s needed.

Other f a c t o r s t h a t con t r i bu ted t o l i m i t e d performance, b u t i n a l ess s i g n i f i c a n t way, inc lude: an inadequate spare p a r t s inventory , l i m i t e d s t a f f expe r t i se i n handl ing emergency maintenance, a l ack o f an a l t e r n a t e power source, a marg ina l l y equipped labora tory , poor a c c e s s i b i l i t y f o r maintenance i n p a r t o f t he p lan t , a l ack o f needed sample taps, and a r e l a t i v e l y "greenll s t a f f .

PROJECTED IMPACT OF A CCP

Improved e f f l u e n t q u a l i t y , t o w i t h i n NPDES permi t l i m i t s , and o v e r a l l opera t iona l s t a b i l i t y , sa fe ty , and a d m i n i s t r a t i v e a b i l i t y t o p r o t e c t t he e x i s t i n g c a p i t a l investment and prov ide f o r f u t u r e wastewater t reatment needs, a re expected i f a CCP i s implemented.

CCP COSTS

Costs associated w i t h a 12-month CCP a t S p r i n g f i e l d would be f o r t he CCP f a c i l i t a t o r and f o r equipment repa i rs , minor mod i f i ca t ions , and

135

I'

It appears t h a t t he RBCs may n o t have q u i t e enough capac i ty t o adequately t r e a t design loadings. RBC capac i ty should be evaluated as f lows approach design.

The u l t i m a t e sludge d isposal c a p a b i l i t y as represented by the sludge d ry ing beds appears t o be the on ly major process t h a t w i l l be l i m i t i n g a t cu r ren t f lows. The l i m i t a t i o n i n u l t i m a t e sludge d isposal is dur ing the w i n t e r when the d r y i n g beds f reeze and do n o t d ry .

PERFORMANCE-LIMITING FACTORS

During the CPE, t he p l a n t ' s per formance- l imi t ing f a c t o r s i n the areas o f design, f a c t o r s

1.

2 .

3 .

4 .

5 .

6 .

admin is t ra t ion , operat ion, and maintenance were i d e n t i f i e d . These a re l i s t e d below and the most s i g n i f i c a n t ones b r i e f l y discussed.

Sewaqe Treatment Understandinq (ODeration). A l ack o f understanding o f b i o l o g i c a l t reatment process fundamentals and opera t iona l requirements and goals s i g n i f i c a n t l y l i m i t p l a n t performance. This l i m i t a t i o n could be addressed w i t h o n s i t e t r a i n i n g over a pe r iod o f months o r by p e r i o d i c attendance a t seminars, schools, etc. , over a per iod o f many years.

Process Contro l Tes t ing (Operat ion). An almost complete l ack o f process c o n t r o l t e s t i n g ex i s ted p r i o r t o the CPE. Base-level t e s t i n g was i n i t i a t e d du r ing the CPE. Onsi te t r a i n i n g i s requ i red t o op t im ize process c o n t r o l t e s t i n g and t o teach the opera t iona l s t a f f t o p roper l y apply the t e s t r e s u l t s t o process con t ro l s .

Return Process Streams (Design). Secondary sludge being returned t o t h e pr imary c l a r i f i e r was causing pr imary c l a r i f i e r "bu lk ing . " Anaerobic d i g e s t e r supernatant r e t u r n w i l l a l s o adverse ly impact p l a n t performance. The c a p a b i l i t y t o minimize t h e adverse impact o f r e t u r n process streams can be acquired through long-term, o n s i t e t r a i n i n g .

EaulDment Ma l func t ion (Maintenance). The waste gas burner, t h e d iges te r gas mix ing system, t h e heat exchanger temperature c o n t r o l system, and the pr imary sludge pump were a l l ou t o f se rv i ce du r ing the CPE. A s i g n i f i c a n t s a f e t y problem, as w e l l as opera t iona l problems, had developed. Admin i s t ra t i ve and opera tor t r a i n i n g a re needed.

Improper T r a i n i ns Guidance ( ODerat 1 on l . Current opera t ion and equipment problems have been e x i s t i n g f o r years desp i te formal grant-supported s t a r t u p o f t he expanded f a c i l i t i e s and p e r i o d i c S ta te inspect ions.

Admin i s t ra t i ve F a m i l i a r i t y With P lan t Needs (Admin i s t ra t i on ) . Through pas t poor communication and improper operat ion, t he p l a n t admin is t ra to rs have been mis led regard ing p l a n t needs. Increased

134

TABLE C-2

SPRINGFIELD, KS, P O W CAPACITY POTENTIAL

Major U n i t Process

Primary C la r i f i e r

RBCS

Flow, m)/d (mgd)

3,000 3,800 4,500 5,300 6,100 6,800 7,600 8,300 9,100 9,800 10,600 (0.8) (1.0) (1.2) (1.4) (1.6) (1.8) (2,O) (2.2) (2.4) (2.6) (2.8)

Secondary C la r i f i e r

Digesters

I I TT71 Ultimate Disposal

Ultimate Disposal Liquid I Haul t o Land

33 m3/&/d (800 gpd/sq ft) Est. 30% 800, removed

3.9 kg SBOD/n?/d (0.8 Ib SB00/d/IJ000 sq f t ) lower than 4.9 kg SsoO/&/d (1.0 Ib SBOD/d/ I ,000 sq f t ) because o f si destrem return

20 m3/d/d (500 gpd/sq ft) because o f configuration

30 min aver-

30 days' detention time 4 . a c d i n e d sludge

42 days* turnover marginally adequate i n sumer

Estimated Current [ksign Flow Flow

The ability to handle current loads was assessed using a numerical point system, which resulted in the plant's being categorized Type 1 , 2, or 3 as described below:

- TyDe 1. Loadings are conservatively low, but performance problems could be alleviated with training and/or minor facility modifications.

- Type 2. Loadings are not conservatively low but also not so high as to preclude improved performance from existing facilities.

- TyDe 3. Loadings are so high in relation to capacity that it is not considered reasonably possible to consistently meet effluent requirements without a major facility upgrade.

The results of the major process evaluation are shown in Table C-1.

TABLE C-1

SPRINGFIELD, KS, POTW MAJOR UNIT PROCESS EVALUATION

Aerator Secondary Clarif ier Sludge Handling Capability Total of Major Processes

Points

26 18 5 49 -

Assessed TyDe

As shown in Table C-1, the aerator, secondary clarifier, and the total o f major processes all received sufficient points to receive a Type 1 classification. Sludge handling capability received a Type 2 classification. The major limitation regarding sludge handling was ultimate sludge disposal capability in winter.

The evaluation of major unit processes indicates that sludge handling will likely require supplemental capacity, but the other major processes have adequate capacity. In general, the CCP approach appears applicable if additional ultimate sludge disposal capacity can be provided.

The potential capacity of major unit processes in the Springfield plant i s illustrated in Table C-2. The horizontal bar graph associated with each major process depicts the potential capacity of that process.

Primary clarifiers, secondary clarifiers, and anaerobic digesters are all belleved to have capacities a little greater than design capacities. The chlorine contact basin has capacity sufficient for design flows; however,

132

RESULTS OF A CPE AT THE SPRINGFIELD, KS, POTW

FACILITY BACKGROUND

The S p r i n g f i e l d POTW i s a r o t a t i n g b i o l o g i c a l con tac tor (RBC) type o f t reatment p l a n t designed f o r an average d a i l y wastewater f l o w o f 7,600 m3/d (2.0 mgd). The p l a n t was o r i g i n a l l y completed as a pr imary t reatment p l a n t i n 1965 and upgraded f o r secondary t reatment i n 1980. The p l a n t serves the Ci ty o f S p r i n g f i e l d w i t h at1 est imated popu la t ion o f 9,000. A r a i l c a r washing opera t ion 1s thought t o be the source o f t h e o n l y s i g n i f i c a n t i n d u s t r i a l waste, b u t sampling has no t confirmed t h i s .

P lan t records i nd i ca ted t h a t wastewater f lows had been averaging c lose t o design f low; however, f l o w c a l i b r a t i o n du r ing the CPE i nd i ca ted t h a t f l o w was a c t u a l l y about 4,500 m3/d (1.2 mgd), o r o n l y 60 percent o f des ign f l ow . Current organic load ing was est imated t o a l s o be about 60 percent o f design.

The S p r i n g f i e l d p l a n t cons is ts o f the f o l l o w i n g u n i t processes:

Vortex g r i t chamber Mechani ca 1 bar screen 23-cm (9- in) Parsha l l f lume L i f t s t a t i o n One 18-m ( 6 0 - f t ) diameter pr imary c l a r i f i e r Four-stage RBCs (12 shaf ts ) Two 6 x 33 m (20 x 110 f t ) secondary c l a r i f i e r s Two-cell c h l o r i n e contac t chamber Two 11-m ( 3 5 - f t ) d iameter anaerobic d iges te rs (Note: Dur ing the CPE, t he second-stage d i g e s t e r was n o t i n serv ice. ) 2,800 m2 (30,000 sq f t ) d r y i n g beds

The S p r i n g f i e l d p l a n t i s requ i red t o meet standard secondary t reatment e f f l u e n t requirements w i t h 20,000/40,000 f e c a l c o l i f o r m l i m i t s . NPDES mon i to r ing data i n d i c a t e performance o f the p l a n t has genera l l y been w i t h i n standards, bu t i n d i v i d u a l analyses i n d i c a t e e r r a t i c performance. Dur ing the CPE, sludge was b u l k i n g f rom both the pr imary and secondary c l a r i f i e r s .

MAJOR UNIT PROCESS EVALUATION

Major p l a n t processes were evaluated f o r t h e i r capac i ty t o adequately t r e a t cu r ren t loadings and the general a p p l i c a b i l i t y o f a CCP t o improve performance. Current hyd rau l i c loadings were est imated w i t h f l o w data measured du r ing t h e CPE. Organic load ing on the RBC as measured by so lub le BODS was est imated us ing 30 percent t o t a l BOD removal i n t h e pr imary c l a r i f i e r and 50 percent o f t he pr imary e f f l u e n t t o t a l BOD as so lub le BOD.

131

A P P E N D I X C

EXAMPLE CPE REPORT

130

CPE SUMMARY SHEET TERMS

PLANT TYPE

DESIGN FLOW

ACTUAL FLOW

YEAR PLANT BUILT

B r i e f bu t s p e c i f i c d e s c r i p t i o n o f type o f p l a n t (e.g., two-stage t r i c k l i n g f i l t e r w i t h anaerobic d i g e s t e r o r extended ae ra t i on a c t i v a t e d sludge w i th p o l i s h i n g pond and w i thou t sludge d iges t i on ) .

P lan t design f l o w r a t e as o f most recent upgrade.

Wastewater f l o w r a t e f o r c u r r e n t opera t ing c o n d i t i o n (e.g., f o r pas t year) . Also, s i g n j f i c a n t seasonal v a r i a t i o n i n f lows should be noted.

Year i n i t i a l u n i t s were p u t i n t o operat ion.

YEAR OF MOST RECENT UPGRADE Year l a s t a d d l t i o n a l major u n i t s were p u t I n t o opera t ion (e.g., d iges ter , c h l o r i n e contac t chamber, e tc . ) .

PLANT PERFORMANCE SUMMARY B r i e f d e s c r i p t i o n o f p l a n t performance as r e l a t e d t o present and a n t i c i p a t e d t reatment requirements.

RANKING TABLE

RANK I NG

I n descending order, a l i s t o f t h e major causes o f decreased p l a n t performance and re1 i a b l 11 t y .

Causes o f decreased p l a n t performance and r e l i a b i l i t y , w i t h the most c r i t i c a l ones l i s t e d f i r s t .

PERFORMANCE-LIMITING FACTORS Categor ies l i s t e d i n the Check l i s t (Appendix A) .

129

CPE SUMMARY SHEET FOR RANKING PERFORMANCE-LIMITING FACTORS

P lan t Name/Location

CPE Performed by Date

P lan t T w e :

Design Flow:

Actual Flow:

Year P lan t B u i l t :

Year o f Most Recent Upgrade:

P1 an t Performance Summary :

r RANKING TABLE

I Ranking I Performance-Limi t i n g Factors I

1 7 1 a 9

1 10 I 11 I I 12 13

I

128

A P P E N D I X 8

CPE SUMMARY SHEET FOR R A N K I N G P E R F O R M A N C E - L I M I T I N G FACTORS

127

b. Technical Guidance

4. O&M Manual

a. Adequacy

b. Use by the Operator

5. Miscellaneous

a. Equipment Ma l func t ion

b. S h i f t S t a f f i n g Adequacy (Operat ions)

Does f a l s e opera t iona l i n fo rma t ion received from a techn ica l consu l tan t cause improper opera t iona l dec is ions t o be cont inued? Does a techn ica l person (e.g., design engineer, equipment representa t ive , S ta te t r a i n e r o r inspec tor ) f a i l t o address obvious opera t iona l d e f i c i e n c i e s w h i l e being i n a p o s i t i o n t o c o r r e c t t he problem?

Does a poor O&M manual used by the operator r e s u l t i n poor o r improper opera t iona l dec is ions?

Does a good O&M manual no t used by t h e operator cause poor process c o n t r o l and poor t reatment t h a t could have been a vo i ded ?

The opera t ion "miscel laneousll category deals w i t h any p e r t i n e n t opera t iona l i n fo rma t ion n o t covered i n the prev ious opera t iona l sect ions. (Space i s a v a i l a b l e i n the Check l i s t t o accom- modate a d d i t i o n a l i tems n o t l i s t e d . )

Does mal func t ion ing equipment cause de- t e r i o r a t e d process performance?

Does the improper d i s t r i b u t i o n o f ade- quate manpower prevent process c o n t r o l s from being made o r made a t i napprop r ia te times, r e s u l t i n g i n poor p l a n t per- formance?

126

2 ) Level o f Educati on

b. C e r t i f i c a t i o n

1) Level o f C e r t i f i c a t i o n

2) T ra in ing

c. Sewage Treatment Understanding

Does a low l e v e l o f educat ion cause poor O&M dec is ions? Does a h igh l e v e l o f educat ion o r a l ack o f process understanding cause needed t r a i n i n g t o be overlooked?

Does the l ack o f adequately c e r t i f i e d operators cause poor process c o n t r o l dec is ions?

Does the opera to r ' s inat tendance a t a v a i l a b l e t r a i n i n g programs cause poor process c o n t r o l dec is ions?

Is t he opera to r ' s l ack o f understanding o f sewage treatment, i n general, a f a c t o r i n poor opera t iona l dec is ions and poor p l a n t performance o r re1 i a b i 1 i t y ?

d. I n s u f f i c i e n t Time Does the s h o r t t ime on t h e j o b cause on Job (Green Crew) improper process c o n t r o l adjustments t o

be made (e.g., opening o r c l o s i n g a wrong valve, t u r n i n g on o r o f f a wrong pump, e tc . )?

2. Tes t ing

a. Performance Mon i to r ing

b. Process Cont ro l Tes t ing

3 . Process Cont ro l Adjustments

Are t h e requ i red mon i to r ing t e s t s be ing completed i n compliance w i t h t h e discharge permi t and a re they t r u l y representa t ive o f p l a n t performance?

Does the absence o r wrong type o f pro- cess c o n t r o l t e s t i n g cause improper opera t iona l c o n t r o l dec is ions t o be made?

a. Operator App l i ca t i on Is t h e opera tor d e f i c i e n t i n the app l ica- o f Concepts and t i o n o f h i s /he r knowledge o f sewage Tes t ing t o Process t reatment and i n t e r p r e t a t i o n o f process Cont ro l c o n t r o l t e s t i n g t o process c o n t r o l

add ustments?

125

2 ) Contro l

h. Lack o f Standby Un i t s f o r Key Equipment

1. Laboratory Space and Equipment

j . Process A c c e s s i b i l i t y f o r Sampl i ng

k. Equipment A c c e s s i b i l i t y f o r Maintenance

1. P lan t I n o p e r a b l l i t y Due To Weather

D. OPERATION

1. S t a f f Q u a l i f i c a t i o n s

a. A b i l i t y

1) Apt i tude

Does t h e lack o f a needed automat ic c o n t r o l dev ice ( t i m e c lock, f l o w a c t i v a t e d con t ro l s , e t c . ) cause excessive opera tor t ime t o make process c o n t r o l changes o r necessary changes t o be cancel led o r delayed? Does t h e breakdown o r the improper workings o f automatic c o n t r o l fea tures cause degradat ion o f process performance?

Does the lack o f standby u n i t s f o r key equipment cause degraded process per- formance du r ing breakdown o r necessary p revent ive maintenance i tems t o be cancel led o r delayed?

Does the absence o f an adequately equipped labo ra to ry l i m i t p l a n t performance by the l ack o f opera t iona l t e s t i n g and performance mon i to r ing?

Does t h e I n a c c e s s i b i l i t y o f var ious process f l o w streams (e.g., recyc le streams) f o r sampling prevent needed in fo rma t ion f rom being obtained?

Does t h e i n a c c e s s i b i l i t y o f var ious pieces o f equipment cause ex tens ive downtime o r d i f f i c u l t y i n making needed r e p a i r s o r adjustments?

Are c e r t a i n u n i t s i n t h e p l a n t extremely vu lnerab le t o weather changes (e.g., c o l d temperatures) and, as such, do n o t operate a t a l l o r do n o t operate as e f f i c i e n t l y as necessary t o achieve t h e requ i red performance?

Does the l ack o f capac i t y f o r l e a r n i n g o r understanding new ideas by c r i t i c a l s t a f f members cause poor OW dec is ions l ead ing t o poor p l a n t performance or r e l i a b i l i t y ?

124

c . Lack o f U n i t Bypass Does the lack o f a u n i t bypass 1) cause p l a n t upset and long-term poor t reatment when a short- term bypass could have minimized p o l l u t i o n a l load t o the rece iv ing waters; 2 ) cause necessary p revent ive o r emergency maintenance i tems t o be cancel led o r delayed; o r 3 ) cause more than one u n i t t o be ou t o f se rv i ce when main ta in ing o n l y one u n i t ?

d. Hydraul ic Prof i l e

1) Flow Backup Does an i n s u f f i c i e n t hyd rau l i c p r o f i l e cause ground f l o o d i n g o r f l o o d i n g o f upstream u n i t s , except c l a r i f i e r s ? Does p e r i o d i c re lease o f backed-up f l o w cause hydraul i c surge?

2) Submerged Weirs Does an i nsuf f i c i en t hydraul i c p r o f i l e cause f l o o d i n g o f c l a r i f i e r s and sub- merged c l a r i f i e r we i rs?

3) Flow Propor t ion ing Does inadequate f l o w p ropor t i on ing o r t o Un i t s f l o w s p l i t t i n g t o d u p l i c a t e u n i t s cause

problems o r p a r t i a l u n i t over loads t h a t degrade e f f l u e n t q u a l i t y o r h inder achievement o f optimum process performance?

e. Alarm Systems

f . A l te rna te Power Source

g. Process Automation

1) Mon i to r ing

Does the absence o r inadequacy o f a good a larm system f o r c r i t i c a l p ieces o f equipment cause unnecessary equipment f a i l u r e o r i n any way cause degraded process performance?

Does the absence o f an a l t e r n a t e power source cause problems i n p l a n t opera t ion lead ing t o degraded p l a n t performance?

Does the l ack o f needed automat ic mon i to r ing devices (DO meter, pH meter, e tc . ) cause excessive operator t ime t o watch f o r s lug loads o r process upset t o occur because o f s lug loads? Does the breakdown o r improper workings o f automated process mon i to r ing fea tures cause d i s r u p t i o n o f automated c o n t r o l fea tures and subsequent degradat ion o f process performance?

123

e. D i s i n f e c t i o n

f . Sludge Wasting C a p a b i l i t y

g. Sludge Treatment

h. U l t ima te Sludge Disposal

3 . Miscellaneous

a. P lan t Locat ion

b. Uni t Process Layout

Does the shape o r l o c a t i o n o f the u n i t c o n t r i b u t e t o i t s accompl ishing d i s i n - f e c t i o n o f the wastewater ( i . e . , proper mixing, de ten t i on t ime, feed ra tes , feeding ra tes p ropor t i ona l t o f low, e t c . ) ?

Does the p l a n t have sludge wast ing f a c i l - i t i e s ? I f so, can des i red volume o f sludge be wasted? Can sludge wast ing be adequately c o n t r o l l e d ? Can sludge wasted be sampled w i thou t extreme d i f f i c u l t y ?

Does the type o r s i z e o f t he s ludge t reatment process h inder sludge s t a b i l i z a t i o n (once sludge has been removed from the wastewater t reatment system), thereby causing process opera t ion problems (e.g., odors, l i m i t e d sludge wasting, e tc . )?

I s the u l t i m a t e sludge d isposal program, i n c l u d i n g f a c i l i t i e s and d isposa l area, o f s u f f i c i e n t s i z e and type t o adequately handle the sludge produc t ion f rom t h e p l a n t ? Are the re any s p e c i f i c areas t h a t l l m l t u l t i m a t e sludge d isposa l such as seasonal weather v a r i a t i o n s o r crop harvest i ng?

The design "miscel laneous" category covers areas o f design inadequacy n o t s p e c i f i e d i n the prev ious design categor ies. (Space i s a v a i l a b l e i n the Check l i s t t o accommodate a d d i t i o n a l i tems no t l i s t e d . )

Does a poor p l a n t l o c a t i o n o r poor roads lead ing i n t o the p l a n t cause i t t o be Inaccess ib le du r ing c e r t a i n per iods o f t he year (e.g., w i n t e r ) f o r chemical o r equipment d e l i v e r y o r f o r r o u t i n e opera t ion?

Does the arrangement o f t he u n i t pro- cesses cause i n e f f i c i e n t u t i l i z a t i o n o f opera tor ' s t ime f o r checking var ious processes, c o l l e c t i n g samples, making adjustments, e tc .?

122

b. Primary

c . Secondary

1) Process F l e x i b i l i t y

2) Process Contro l lab1 1 1 t y

3 ) 'I Ae r a t o r

4) C l a r i f i e r

d. Advanced Waste Treatment

Does the shape o r l o c a t i o n o f t h e u n i t c o n t r i b u t e t o i t s accompl ishing the task o f pr imary t reatment? Does the u n i t have any design problem area w i t h i n i t t h a t has caused i t t o perform poor l y?

Does the u n a v a i l a b i l i t y o f adequate valves, p ip ing , e tc . , l i m i t p l a n t performance and r e l i a b i l i t y when o the r modes o f opera t ion o f t h e e x i s t i n s D lan t can be u t i l i z e d t o improve performance (e,g., operate a c t i v a t e d sludge p l a n t i n p lug, step, o r con tac t s t a b i l i z a t i o n mode; operate t r i c k l i n g f i l t e r w i t h constant hyd rau l i c load ing o r r e c i r - c u l a t i o n r a t i o ; d ischarge good secondary t reatment e f f l u e n t as opposed t o a degraded " p o l i s h i n g pond" e f f l u e n t ) ?

Do t h e e x i s t i n g process c o n t r o l fea tures prov ide adequate adjustment and measure- ment over the appropr ia te f lows (e.g., r e t u r n sludge) i n the range necessary t o op t im ize process performance, o r i s t he f l ow d i f f i c u l t t o ad jus t , v a r i a b l e once adjusted, n o t measured and recorded, n o t e a s i l y measurable, e tc .?

Does t h e type, s ize, shape, o r l o c a t i o n o f t h e tlaeratorll ( a e r a t i o n basin, t r i c k l i n g f i l t e r , RBC, e tc . ) h inder i t s a b i l i t y t o adequately t r e a t t h e sewage and prov ide f o r s t a b l e opera t ion? Is oxygen t r a n s f e r capac i ty inadequate?

Does a d e f i c i e n t des ign cause poor sedimentat ion due t o t h e s ize, type, o r depth o f t h e c l a r i f i e r ; placement o r l eng th o f t he wei rs ; o r o the r miscel laneous problems?

Advanced waste t reatment i s any process o f wastewater t reatment t h a t upgrades water q u a l i t y t o meet s p e c i f i c e f f l u e n t l i m i t s t h a t cannot be met by conven- t i o n a l pr imary and secondary t reatment processes (1 .e., n i t r i f i c a t i o n towers, chemical t reatment, mu1 f i med I a f i l t e r s ) . (Space i s a v a i l a b l e i n the Check1 1 s t t o accommodate advanced processes encountered du r ing t h e CPE.)

121

3 . Emergency

a. S t a f f Exper t i se Does the p l a n t s t a f f have the necessary exper t i se t o keep the equipment opera t ing and t o make smal le r equipment r e p a i r s when necessary?

b. C r i t i c a l Par ts Do delays i n g e t t i n g replacement p a r t s Procurement cause extended per iods o f equipment

downtime?

c. Technical Guidance If techn ica l guidance f o r r e p a i r i n g o r i n s t a l l i n g equipment i s necessary t o decrease equipment downtime, i s i t a v a i l a b l e and re ta ined?

C. DESIGN

1, P lan t Loading

a. Organic

b, Hydrau l i c

c. I n d u s t r i a l

d. Toxic

e. Seasonal V a r i a t i o n

f . I n f 11 t r a t i o n / I n f low

g. Return Process Streams

2. U n i t Design Adequacy

a. P re l im ina ry

Does the presence o f "shock" load ing c h a r a c t e r i s t i c s over and above what t h e p l a n t was designed f o r , o r over and above what i s thought t o be to le rab le , cause degraded process performance by one o r more o f t he loadings (a-e) l i s t e d be 1 ow?

Does excessive i n f i l t r a t i o n o r i n f l o w cause degraded process performance because t h e p l a n t cannot handle the e x t r a f low?

Does excessive volume and/or a h i g h l y organic o r t o x i c r e t u r n process f l ow stream cause adverse e f f e c t s on process performance, equipment problems, e tc .?

Do t h e des ign fea tures o f any pre l im- i n a r y t reatment u n i t cause upsets i n downstream equipment wear and t e a r t h a t has led t o degraded p l a n t performance?

120

B. MAINTENANCE

1. General

a. Housekeeping

b. Equipment Age

c. Scheduling and Record1 ng

d. Manpower

2. Prevent i ve

a. Lack o f Program

Does a lack o f good housekeeping procedures (e.g., g r i t channel c leaning; bar screen cleaning; unkempt, un t idy , o r c l u t t e r e d working environment) cause an excessive equipment f a i l u r e r a t e ?

Does the age o r outdatedness o f c r i t i c a l p ieces o f equipment cause excessive equipment downtime and/or i n e f f i c i e n t process performance and re1 i a b i 15 t y (due t o u n a v a i l a b i l i t y o f replacement p a r t s ) ?

Does the absence o r l ack o f an e f f e c t i v e maintenance schedul ing and record ing procedure c rea te a c o n d i t i o n f o r an e r r a t i c p revent ive maintenance program t h a t r e s u l t s i n unnecessary equipment f a i 1 ure?

Does the l ack o f adequate maintenance manpower r e s u l t i n p revent ive main- tenance func t ions ( t o prevent equipment breakdown) n o t be ing completed o r i n emergency equipment repa i r s be ing delayed ?

Does the absence o r l ack o f an e f f e c t i v e maintenance program cause unnecessary equipment f a i l u r e s o r excessive downtime t h a t r e s u l t s i n p l a n t performance o r r e l i a b i l i t y ?

b. References Ava i l ab le Does the absence o r l ack o f good equip- ment re ference sources cause unnecessary equipment f a i l u r e and/or downtime f o r r e p a i r s ( inc ludes maintenance p o r t i o n o f OM manual)?

c. Spare Par ts Inventory Does a c r i t i c a l l y low o r nonexis tent spare p a r t s i nven to ry cause unnecessary long delays i n equipment r e p a i r s t h a t r e s u l t i n degraded process performance?

d. Workload Distribution Does uneven d i s t r i b u t i o n o f p revent ive maintenance tasks cause neg lec t o f o the r impor tant d u t i e s a t c e r t a i n times o f t h e month o r year?

119

b. Morale

1) Mo t i va t i on Does the p l a n t s t a f f want t o do a good j o b because they a re mot ivated by s e l f - s a t i s f a c t i o n ?

Does a low payscale discourage more h i g h l y q u a l i f i e d persons from app ly ing f o r opera tor p o s i t i o n s o r cause operators t o leave a f t e r they a r e t r a i n e d ?

3) Superv is ion Does the working r e l a t i o n s h i p o f t h e p l a n t super intendent and operator o r superv isor and opera tor cause adverse operator i ncen t i ve?

4) Working Condit ions Does a poor working environment c rea te a c o n d i t i o n f o r more "s loppy work h a b i t s " and lower operator morale?

c . P r o d u c t i v i t y Does the p l a n t s t a f f conduct t he d a i l y opera t ion and maintenance tasks i n an e f f i c i e n t manner? I s t ime used e f f i - c i en t 1 y?

d. Personnel Turnover Does a h igh personnel tu rnover r a t e cause opera t ion and/or maintenance problems t h a t a f f e c t process performance o r re1 i a b i 1 i t y ?

3 . F inanc ia l

a. I n s u f f i c i e n t Funding Does the l ack o f a v a i l a b l e funds cause poor sa la ry schedules, i n s u f f i c i e n t stock o f spare p a r t s t h a t r e s u l t s i n delays i n equipment repa i r , i n s u f f i c i e n t c a p i t a l o u t l a y f o r improvements, e tc .?

b. Unnecessary Expend 1 t u r e s

c. Bond Indebtedness

Does t h e manner i n which a v a i l a b l e funds a r e dispersed cause problems i n ob ta in ing needed equipment, s t a f f , e tc .? Are funds spent on lower p r i o r i t y i tems w h i l e needed, h igher p r i o r i t y i tems a r e unfunded?

Does t h e annual bond debt payment l i m i t t he amount o f funds a v a i l a b l e f o r o ther needed items such as equipment, s t a f f , e tc .?

118

GUIDELINES FOR INTERPRETING PERFORMANCE-LIMITING FACTORS

Catesory Explanat ion

A. ADMINISTRATION

1. P lan t Admin is t ra to rs

a. P o l i c i e s

b. F a m i l i a r i t y w i t h P lan t Needs

2. P lan t S t a f f

a. Manpower

1) Number

2) P lan t Coverage

Do the appropr ia te s t a f f members have t h e a u t h o r i t y t o make requ i red dec is ions regard ing opera t ion (e.g., a d j u s t va lve) , maintenance (e.g., h i r e e l e c t r i c i a n ) , and/or admin i s t ra t i on (e.g., purchase c r i t i c a l p iece o f equipment) dec is ions, o r do t h e admin i s t ra t i on p o l i c i e s r e q u i r e a s t r i c t adherence t o a "chain o f command'' (which has caused c r i t i c a l dec is ions t o be delayed and i n t u r n has a f f e c t e d p l a n t performance and r e l i a b i l i t y ) ? Does any es tab l i shed a d m i n i s t r a t l v e p o l i c y l i m i t p l a n t performance?

Do the admin i s t ra to rs have a f i r s t -hand knowledge o f p l a n t needs through p l a n t v i s i t s , d iscuss ions w i t h operators, e tc .? I f not, has t h i s been a cause o f poor p l a n t performance and re1 i a b i 1 i t y through poor budget dec is ions, poor s t a f f morale, poor opera t ion and maintenance procedures, poor design dec is ions, e tc .?

Does a l i m i t e d number o f people employed have a de t r imenta l e f f e c t on p l a n t oper- a t i o n s (e.g., n o t g e t t i n g the necessary work done)?

Does the t ime pe r iod o f p l a n t opera t ion cause unnecessary opera t iona l ad jus t - ments t o be made o r i n e f f i c i e n t use o f t h e number o f people on the s t a f f (e.g., operators g e t t i n g i n each o t h e r ' s way)?

117

C H E C K L I S T OF PERFORMANCE-LIMITING F A C T O R S ( c o n t i n u e d )

Factor

a. Operator A p p l i c a t i o n o f Concepts and Test ing t o Process Control

b. Technical Guidance

E

Rat ing Comments

r---- ~

I

4. O&M Manual

a. Adequacy

I I

b. Use by Operators

5. M i scel 1 aneous

r

d.

e.

f.

9.

h.

i.

I a. Equipment Mal funct ion I I I I b. S h i f t S t a f f i n g Adequacy I I I

(Operations ) C.

116

C H E C K L I S T OF P E R F O R M A N C E - L I M I T I N G FACTORS (cont inued)

Factor Rat ing Come n t s

1) Moni t o r i ng

2) Control h . Lack o f Standby Un i t s

for Ke.y Equi p n m t i. Laboratory Space and

Equipment j. Process Accessi b i l i ty

f o r Samplinq k. Equipment Accessi b i 1 i ty

f o r Maintenance 1. P lan t I n o p e r a b i l i t y Due

- To Weather m.

n. I

D. OPERATION - 1. S t a f f Q u a l i f i c a t i o n s

a. A b i l i t y

1) Ap t i t ude

1 b. C e r t i f i c a t i o n

1) Level o f

2 ) T r a i n i n g

c. Sewage Treatment Understandinq

d. I n s u f f i c i e n t Time on t h e Job (Green Crew)

C e r t i f i c a t i o n

2. Test ing

a. Performance Mon i to r i ng

b. Process Control Test ing ~~ ~~ ~~~

~ 3. Process Contro l Adjustments I I I

115

C H E C K L I S T O F P E R F O R M A N C E - L I M I T I N G FACTORS (cont inued)

Factor Rat ing Comments ~

1) Process F l e x i b i 1 i ty

2 ) Process Control 1 ab i l i t v

3 ) "Aerator "

-~~

b. U n i t Process Layout

c. Lack o f U n i t Bypass

d. Hydraul i c Pro f i 1 e

4 ) C l a r i f i e r

d. Advanced Waste Treatment

~~~

e. D i s i n f e c t i o n

f. Sludge Wasting CaDabi 1 i t v

g. Sludge Treatment

h. U l t ima te Sludge DisDosal

3. M i sce l 1 aneous

a. P lan t Locat ion

1) Flow Backup

2 ) Submerged Weirs

3 ) Flow Propor t ion ing t o Un i t s

e. Alarm Systems

~ f. A l t e r n a t e Power Source

g. Process Automation 1 I I I

114

CHECKLIST OF PERFORMANCE-L IMIT ING FACTORS (cont inued)

Factor

c. Scheduling & Recording

d. Manpower

2. Prevent ive

I I I

Rating Comme n t s

I ~ ~~

I I

a. Lack o f Program

b. References Ava i l ab le

c. Spare Par ts Inventory

d. Workload D i s t r i b u t i o n

3. Emergency

a. S t a f f Exper t i se b. C r i t i c a l Par ts

Procurement c. Technical Guidance

C. DESIGN

1. P lan t Loading

a. Organic

b . Hydrau l i c

c. I n d u s t r i a l

d. Toxic

e. Seasonal V a r i a t i o n

f. I n f i l t r a t i o n / I n f l o w

g. Return Process Streams

2 . U n i t Design Adequacy

a. Pre l i m i nary

~ b. Primary

c. Secondary

CHECKLIST O F PERFORMANCE-L IMIT ING FACTORS

Factor

A. ADMINISTRATION

1. P lan t Admin is t ra tors

a. P o l i c i e s

b. F a m i l i a r i t y w i t h P l a n t Nee ds

2. P lan t S t a f f

a. Manpower

1) Number

2 ) Plant Coverage

b. Morale

1) Mot iva t ion

2) Pay

3 ) Supervi s i on

4 ) Working Condit ions

c. P r o d u c t i v i t y

d. Personnel Turnover

3. F inanc ia l

a. I n s u f f i c i e n t Funding

b. Unnecessary Expenditures

c. Bond Indebtedness

B. MAINTENANCE

1. General

a. Housekeeping

b . Equipment Age

Rat ing Comments

112

CLASSIFICATION SYSTEM FOR PRIORITIZING PERFORMANCE-LIMITING FACTORS

Rat I n g Adverse E f f e c t o f F a c t o r on P l a n t Performance

A

B

C

Major e f f e c t on a long-term r e p e t i t i v e b a s i s

Minimum e f f e c t on a r o u t i n e b a s i s or major e f f e c t on a p e r i o d i c b a s i s

Minor e f f e c t

111

A P P E N D I X A

CPE C L A S S I F I C A T I O N SYSTEM, C H E C K L I S T , AND G U I D E L I N E S FOR P E R F O R M A N C E - L I M I T I N G FACTORS

110

10.

11.

12.

13.

14.

15.

16.

17.

18.

Jenk ins , D. and W . E. Garr ison. Control of Act ivated Sludge by Mean Cell Residence Time. JWPCF 40(11):1905-1919, 1968.

Palm J. C . , D. Jenkins, and D. S. Parker. The Relat ionship Between Organic Loading, Dissolved Oxygen Concentrat ion, and S1 udge S e t t l e a b i l i t y i n the Completely-Mixed Act ivated S1 udge Process. Paper presented a t the 5 1 s t Annual Conference, Water Po l lu t ion Control Federa t ion , Anaheim, C A Y 1978.

Wooley, J. F. Oxygen Uptake: Operational Control Tests f o r Wastewater Treatment Facil i ties. EW008446, U . S. Environmental P ro tec t ion Agency, In s t ruc t iona l Resources Center, Col umbus, OH, 1981.

McKinney, R. E. Testing Aeration Equipment i n Conventional Act ivated S1 udge P1 an t s . JWPCF 53(1):48-58, 1981.

Process Control Manual f o r Aerobic Biol oqical Wastewater Treatment Fac i l i t i es . EPA-430/9-77-006, NTIS No. PB-279474, U.S. Environmental P ro tec t ion Agency, Of f i ce of Water Program Operat ions, Washington, DC, 1977.

C u l p , G. L . and N. F. Helm. F ie ld Manual for Performance Evaluation and Troubleshoot ing a t Municipal Wastewater Treatment Faci l i t ies. EPA-430/9-78-001 , NTIS No. PB -27 9448, U. S. Environmental P r o t e c t ion Agency, Of f i ce of Water Program Operat ions, Washington, DC, 1978.

Germain, J. E. Economic Treatment of Domestic Waste by Plastic-Medium Trick1 ing Filters. JWPCF 38(2):192-203, 1966.

Rakness, K. L . , J . R. Schul tz , B. A. Hegg, J. C. Cranor, and R. A. Ni sbet. F u l l Sca le Eva1 ua t ion of Act ivated Bio-Fil ter Wastewater Treatment Process. EPA 600/2-82-057, NTIS No. PB-82-227505, U. S. Environmental P ro tec t ion Agency , Municipal Environmental Research Laboratory, Cincinnat i , OH, 1982.

Hegg, B. A., K. L. Rakness, and J. R. Schul tz . A Demonstrated Approach f o r Improving Performance and Re1 i a b i l i t y of Biological Wastewater

Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnati , OH, 1979.

Treatment Plants. EPA-600/2-79-035, NTIS NO. PB-300476, U. S.

109

5.10 References

When an N T I S number i s c i t e d i n a reference, t h a t reference i s a v a i l a b l e from:

Nat ional Technical I n fo rma t ion Service 5285 Por t Royal Road S p r i n g f i e l d, VA 22161 ( 703 ) 487 -4650

1.

2.

3.

4.

5.

6.

7.

8.

9.

Schultz, J. R., B. A. Hegg, and C. S. Zickefoose. Colorado CCP Demonstration and Development o f Areawide Compl iance Strategy. D r a f t Report, U.S. Environmental P r o t e c t i o n Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1984.

Hegg, B. A., K. L. Rakness, and J. R. Schultz. Evaluat ion o f Operation and Maintenance Factors L i m i t i n g Municipal Wastewater Treatment P l a n t Performance. EPA-600/2-79-034, N T I S No. PB-300331, U. S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C i n c i n n a t i , OH, 1979.

Hegg, B. A. , K. L. Rakness, J. R. Schultz, and L. D. Demers. Evaluat ion ' o f Operation and Maintenance Factors L i m i t i n g Municipal Wastewater Treatment P l a n t Performance - Phase 11. EPA-600/2-80-129, NT IS No. PB-81-112864, U.S. Environmental P ro tec t i on Agency, Municipal Environmental Research Laboratory, C inc inna t i , OH, 1980.

Gray, A. C., Jr., P. E. Paul , and H. D. Roberts. Evaluat ion o f Operation and Maintenance Factors L i m i t i n g B i o l o g i c a l Wastewater Treatment P1 an t Performance. EPA-600/2 -7 9-087, NT IS No. PB -297491, U. S. Environmental P ro tec t i on Agency, Munici pal Environmental Research Laboratory, C i n c i n n a t i , OH, 1979.

Maintenance Management Systems f o r Municipal Wastewater F a c i l i t i e s . EPA-430 /9 -74-004, NT IS No. P6 -25661 1 , U . S. Env i ronmen t a l P r o t e c t i o n Agency, O f f i c e o f Water Program Operations, Washington, DC, 1973.

P1 ant Maintenance Program. Manual o f P r a c t i c e OM-3, Water P o l l u t i o n Control Federation, Washington, DC, 1982.

Roberts, H. D., A. C. Gray, Jr., and P. E. Paul. Model Protocol f o r t h e Comprehensive Eva1 u a t i o n o f Pub1 i c l y Owned Treatment Works Performance

Environmental P r o t e c t i o n Agency, Munic i pal Environmental Research Laboratory, C inc inna t i , OH, 1981.

and Operation. EPA-600/2-82-015, NT IS NO. PB-82-180480, U.S.

Jenkins, D., M. Sezgin, and D. S. Parker. A U n i f i e d Theory of Fi lamentous Ac t i va ted S1 udge Bulk ing. Presented a t the 49 th Annual Conference, Water P o l l u t i o n Control Federation, Minneapolis, MN, 1976.

~ Updated Summary o f t h e Operational Control Procedures for t h e Ac t i va ted S1 udge Process. EW006973, U. S. Environmental P r o t e c t i o n .Agency, I n s t r u c t i o n a l Resources Center, Col umbus, OH.

108

100 -

80-

60-

40.

20'

0

FIGURE 5-8

GRAPHICAL PRESENTATION OF IMPROVED PERFORMANCF FROM A SUCCESSFUL CCP

I I j - A,, I

< Permit Standard I

1: . - \ / , I \ - I I

' V I I BOD, f q,

/ \ AV' - w J A J 0 J A J 0 J A J 0 J A J

1977 1978 1979 1980

FORM D-3 (cont inued)

DESIGN DATA

8. UNIT PROCESSES:

Primary Treatment

Primary C l a r i f i e r ( s) :

Number Surface Dimensions

Water Depth (Shal lowest) f t x 0.3 = m Water Depth (Deepest) f t x 0.3 = m

Weir Locat ion

Weir Length f t x 0.3 = m 2 Tota l Surface Area - sq f t x 0.093 = m 3 Tota l Volume cu f t x 0.028 = m

Flow (Design) mgd x 3,785 = m3 /d

(Operat ing) mgd x 3,785 = m3/d

Weir Overf low Rate ( Des 1 gn) gpd / f t x 0.012 = m /m/d (Operat ing) gpd / f t x 0.012 = m3/m/d

3

Surface S e t t l i n g Rate

( Des gn) gpd/sq f t x 0.04

(Operating) gpd/sq f t x 0.04 Hydraul ic Detent ion Time (Design) h r

3 2 m /m /d 3 2 - - m /m /d

- -

(Operating) h r

C o l l e c t o r Mechanism Name Model Horsepower

Scum C o l l e c t i o n and Treatment:

Scum Volume:

Normal : cu f t / d x 0.028 =

Peak: cu f t / d x 0.028 =

m3/d

m3 /d

157

FORM D-3 (cont inued)

DESIGN DATA

B. U N I T PROCESSES

Secondary Treatment

Aerat ion Basin(s) : No. o f Basins Surface Dimensions

Water Depth f t x 0.3 = m 3 Tota l Volume c u f t x 0.028 = m

Flow (Design) mgd x 3,785 = m /d (Operat ing) mgd x 3,785 = m3/d

Sewage Detent ion Time (Design h r (Operat ing) h r

BOD5Loadi ng (Design) lb/d/1,000 cu f t x 0.16 = kg/m3/d

( Ope r a t i ng)

3

kg/m 3 /d lb/d/1,000 cu f t x 0.16 =

Covered? Type o f Aera t ion No. o f Aerators Name Model Horsepower

Modes o f Operat ion (Current and Other Opt ions):

Types o f D i f f u s e r s Manufacturer

No. o f Blowers Name

Mod e 1 Depth f t x 0.3 = m

Model Horsepower

A i r Capaci ty (cfm) Locat ion

Oxygen Transfer Capacity l b / d x 0.454 = kg/d

Comnents :

158

FORM 0-3 (cont inued)

DESIGN DATA

8. U N I T PROCESSES:

Secondary Treatment

Contact Basin:

Surface Dimension Water Depth f t x 0.3 = m

3 Vol ume cu f t x 0.028 = m Flow (Design) mgd x 3,785 = m3 /d

m3 /d . Sewage Detent ion Time (Design) min (Operat ing) mi n

( Opera t 1 ng ) mgd x 3,785 =

Covered?

Comments :

Reaerat lon Basin: Sur f ace D i mens 1 ons Mat e r Depth f t x 0.3 = m

3 Volume cu f t x 0.028 = m

Hydraul ic Detent ion Time a t 100% Return

F l e x i b i l i t y t o Operate as Conventional o r Step Feed:

(Design) h r (opera t ing) h r

Covered?

Comments :

159

FORM 0-3 (cont inued)

DESIGN DATA

B. UNIT PROCESSES:

Secondarv Treatment

Oxygen Transfer:

Type o f Aerat ion

Model Horsepower Capac i t y

No. o f Blowers Name Model Horsepower Capacity Locat ion

Type o f D i f f users

Model Depth f t x 0.3 = m

No. o f Aerators - Name

c f m x 0.028 = m3/mi n

l b / d x 0.454 = kg/d

c f m x 0.028 = m /min 3

Manufacturer

Comments :

160

FORM 0-3

DESIGN DATA

6. UNIT PROCESSES:

Secondary Treatment

T r i c k l i n g F i l t e r :

No. o f F i l t e r s Covered?

Surface Dimensions

Media Type 2 3 sq f t / c u f t x 32.8 = m /m

Media Depth f t x 0.3 = m 2 Surface Area f t x 0.093 = m 3 Media Volume cu f t x 0.028 = m

F1 ow ( Design) mgd x 3,785 = m /d (Operat ing) mgd x 3,785 = m3/d

Organic Loading (Design) lb/d/1,000 cu f t x 0.016 = kg /m3/d

( Opera t i ng ) kg /m3 /d

Hydraul ic Loading 3 2 (Design) gpd/sq f t x 0.04 = m /m /d 3 2 (Operating) gpd/sq f t x 0.04 = m /m /d

Spec i f i c Surf ace

3

lb/d/1,000 cu f t x 0.016 =

R e c i r c u l a t i o n (desc r ip t i on , ranges, c u r r e n t opera t ion) :

Mode o f Operation:

C o m n t s :

161

FORM 0-3 (cont inued)

DESIGN DATA

B. UNIT PROCESSES:

Secondarv Treatment

Rota t ing B i o l o g i c a l Contactor (RBC) :

No. o f Shaf ts - Length o f Shaf ts f t x 0.3 = m 3 No. o f C e l l s C e l l Volume cu f t x 0.028 = m

Name Disc Diameter f t x 0.3 = m

R PM Per iphera l V e l o c i t y f t / sec x 0.3 = m/s ec

2 To ta l Surface Area sq f t x 0.093 = m Percent Submergence

Flow (Design) mgd x 3,785 = m3 /d (Operat ing) mgd x 3,785 = m3/d

Hydraul ic Loading: ( Design) gpd/sq f t x

(Operat ing) gpd/sq f t x C

0 Temperature (Design)

Organic Loading (Design)

(Operat ing)

3 2 3 2

0.04 = m /m /d 0.04 = m /m /d

C (Operat ing)

l b SBOD/d/1,000 sq f t x 4.88 - - g SBOD/m2/d

l b SBOD/d/1,000 sq f t x 4.88 - - g SBOD/m2/d

0

Tota l Detent ion Time (Design) h r (Operat ing) h r Cove red? Heated?

F l e x i b i l i t y t o D i s t r i b u t e Load t o Stages:

Comnents :

162

. I , .

FORM 0-3 (cont inued)

DESIGN DATA

6. UNIT PROCESSES

Secondary Treatment

Ac t iva ted B i o f i l t e r (ABF)

B i o c e l l : Model No. o f Ce l l s Surface Dimensions

Tota l Surface Area sq f t x 0.093 = m Media Depth f t x 0.3 = m To ta l Media Volume cu f t x 0.028 = m

m /m

2 2 3

. Media Type S p e c i f i c Surface sq f t / c u f t x 32.8 2 3 - -

BOD5 Loading

(Design) lb/1,000 cu f t / d x 0.016 = kg/m3/d ( Opera t i ng ) kg/m3/d

Rec i r cu la t i on Tank: Dimensions (LxWxD) f t = m 3 Vo 1 ume cu f t x 0.028 = m

Aera t ion Basin: Surface Dimensions 2 Tota l Surface Area sq f t x 0.093 = m

Depth f t x 0.3 = m 3 Volume cu f t x 0.028 = m

Hydrau l i c Detent ion Time (Design) min (Operat ing) m i n

lb/1,000 cu f t / d x 0.016 =

Comments :

163

FORM 0-3 (cont inued)

DESIGN DATA

B. UNIT PROCESSES

Secondary Treatment

Secondary C l a r i f l e r ( s ) :

No. o f C l a r i f i e r s Dimens 1 on( s ) Water Depth (Shal lowest) f t x 0.3 = m

(Deepest) f t x 0.3 = m

We1 r Locat ion

Percent o f C l a r i f i c a t l o n Developed by Launders . Weir Length f t x 0.3 = m

2 Surface Area sq f t x 0.093 =- m 3 Volume cu f t x 0.028 = m

Flow (Design) mgd x 3,785 m3 /d (Operat ing) mgd x 3,785 m3/d

We1 r Overf low Rate (Design) gpd / f t x 0.012 = m3/m/d

(Operat ing) gpd / f t x 0.012 = m /m/d

Surface S e t t l i n g Rate

( Des 1 gn) (Operat ing)

Hydraul ic Detent ion Time ( Des 1 gn) h r ( Operat i ng) hr

C o l l e c t o r Mechanism Name Model Ho r s e powe r Return Sludge C o l l e c t o r Mechanism Type

Scum C o l l e c t i o n and Removal: Scum Volume: (Normal) gpd x 0.028 = m3 /d

(Peak) gpd x 0.028 = m3/d

Comnents :

3

m 3 2 /m /d m 3 2 /m /d

gpd/sq f t x 0.04 =

gpd/sq f t x 0.04 =

164

FORM 0-3 (cont inued)

DESIGN DATA

B. UNIT PROCESSES:

Return S1 udne

Descr ip t ion o f Sludge Movement ( 1 .e., scrap t o c l a r i f i e r hopper, pump t o a e r a t i o n bas in i n l e t channel):

C o n t r o l l a b l e Capacity Range:

( Low) mgd x 3,785 = m3 /d (High) mgd x 3,785 = m3/d

Method o f Control :

Sampling Locat ion:

Comnents :

Waste Sludge

Descr ip t ion of Waste Procedure ( i .e., variable-speed pump wastes f rom separate c l a r i f i e r hopper, continuous o r by t imeclock) :

Method of Waste Volume Measurement: Sampl i ng Locat i o n :

Comnents:

165

FORM D-3 (cont inued)

DESIGN DATA

B. U N I T PROCESSES:

F D i s i n f e c t i o n

Contact Basin(s) : No. o f Separate Basins

Surface DSmension(s) Channel Length-to-Width Rat io No. o f Bends Water Depth f t x 0.3 = m

3 Tota l Volume cu f t x 0.028 = m Detent ion Time (Design) min (Operat ing) m i n

Dra in Capabi 11 t y :

Scum Removal ‘Capabil l t y :

Comments :

Ch lo r ina to r (s ) : Name No. o f Ch lor ina tors Capaci ty l b / d x 0.454 kg/d

Type o f I n j e c t i o n Flow Proport ioned? Feed Rate (Operat ing) l b / d x 0.454 = kg/d

Chlor ine D i f f u s i o n

Comments :

Dosage (Operat ing) mg/l

166

Form D-3 (cont inued)

DESIGN DATA

8. U N I T PROCESSES:

Sludge Handl ing Aerobic Digest ion:

No. o f Basins Surface Dlmension(s)

Water Depth f t x 0.3 = m 3 Vo 1 ume C U f t x 0.028 = m

Covered? Heated? Type o f Aerat I on

Supernatant C a p a b i l i t y

No. o f Aerators Name

Model Horsepower

Type o f D i f f u s e r s Manufacturer

Model Depth f t x 0.3 = m No. o f Blowers Name

Model Horsepower

Oxygen Transfer Capacl t y l b / d x 0.454 = kg/d Locat ion

A i r Capaci ty cfm x 0.47 = 1 /s

Mode o f Operation:

Comments :

167

FORM 0-3 (cont inued)

DESIGN DATA

B. U N I T PROCESSES:

Sludse Handl ing

Anaerobic Digest ion:

No. o f Digesters D i ame t e r f t x 0.3 = m Sidewal l Depth f t x 0.3 = m

Center Depth f t x 0.3 = m 3 To ta l Volume cu f t x 0.028 = m

F l o a t i n g Cover? Flow (Design) mgd x 3,785 = m3/d

(Operat ing) mgd x 3,785 = m3/d Detent ion Time (Design) days (Operat ing) days

Heat ing :

Mixing:

Sampl i ng Por ts :

Mode o f Operation:

Comments :

168

FORM 0-3 (cont inued)

DESIGN INFORMATION

8. U N I T PROCESSES:

Sludae Handl ing

Sludge Dry ing Beds:

No. o f Beds Size o f Beds Cove red? Subnatant Dra in To

Dewatered Sludge Removal:

Mode o f Operation:

Comments :

Other Dewatering Un i t ( s ) :

No. of Un i t s Type o f U n i t ( s ) Ma nu f ac t u r e r Model Horsepower Hr/Wk

Loading Rate l b / h r x 0.454 = kg/h Po 1 yme r Used

l b / d r y t o n x 0.5 = g/kg Cake So l i ds X So l ids

Comments :

1 69

FORM D-3 (continued)

DESIGN DATA

8. UNIT PROCESSES:

- I t e m

Sumnary o f P l a n t Horsepower

- HP Usage ( X ) Weishted HP

170

FORM 0-3 (continued)

DESIGN DATA

C . OTHER DESIGN INFORMATION:

Standby Power (descr ip t ion o f u n i t ; automatic a c t i v a t i o n ? capaci ty f o r which processes? frequency of use, e t c . ) :

Alarm Systems (descr lp t ion o f system, u n i t s covered, e t c . ) :

Miscellaneous:

171

FORM 0-3 (cont inued)

DESIGN DATA

D.

E.

PLANT AUTOMATION ( d e s c r i p t i o n o f any p l a n t automation n o t covered under more s p e c i f i c t o p i c s ) :

LABORATORY CAPABILITY:

Locat ion F l o o r Dimensions Counter Space f t x 0.3 = m Hot Water?

F i l e Cabinet? Desk? Tests Performed by Whom?

Moni to r ing Tests Conducted (TSS, BOO, pH, Fecal Col i form, Others): According t o Permit

Tests Conducted More Frequent ly Tests Conducted Less Frequent ly

Tests w i th Suspected o r Known A n a l y t i c a l Problems

Operat ional Test C a p a b i l i t y (Equipment/Chemicals): (Check I f ava i l ab le )

DO meter

BOO5 Mal lory- type se t t leometer

Graduated c y l i n d e r Imhoff cone

Turbid1 t y

Amon i a N i t r a t e

172

FORM D-3 (continued)

DESIGN DATA

E . LABORATORY CAPABILITY:

Operat ional Test Capabi l i ty : (Check i f a v a i l a b l e )

Tota l K je ldah l n i t rogen

Suspended so l ids

V o l a t i l e suspended sol ids Sludge b lanket depth measurement Core sample t a k e r

A1 k a l i n 1 t y

V o l a t i l e ac ids

pH meter Centr i fuge sol i d s concentrat ions Oxygen uptake r a t e s

.

173

FORM 0-4

OPERATIONS DATA

A. PROCESS CONTROLS:

Who sets major process c o n t r o l s t r a t e g i e s and dec is ions?

Where i s he lp sought when des i red performance ' i s n o t achieved?

Are s t a f f members asked t h e i r op in ions?

B. .SPECIFIC PROCESS CONTROLS:

Primarv Clarification 1. Sludge Removal:

2. Performance Moni tor ing:

3 . Other:

Suspended Growth POTW Secondarv Systems

1. Sludge Mass Contro l :

2. Return Sludge Contro l :

3 . DO Contro l :

4. C l a r i f i e r So l i ds Loading:

5. Other:

174

FORM D-4 (cont inued)

OPERATIONS DATA

Fixed F i l m POTW Secondary Systems 1. Secondary C l a r i f i e r Sludge Removal:

2, Anaerobic Sidestream Returns:

3 . Other:

Sludqe Handl ing

1. Purpose Re la t i ve t o Other Processes:

2. Sludge S t a b l l l z a t i o n :

3 . Sludge Disposal :

4. Other:

C. PROCESS CONTROL REFERENCES USED ( S p e c i f i c a l l y note references t h a t a re t h e source o f poor process c o n t r o l dec is ions o r s t ra teg ies , suspected o r d e f i n i t e l y i d e n t i f i e d ) :

175

FORM D-5

MAINTENANCE DATA

A. EQUIPMENT OR PROCESSES OUT OF SERVICE DUE TO BREAKDOWNS ( I d e n t i f y equipment o r process, d e s c r i p t i o n o f problem, l eng th o f t ime ou t o f serv ice, what has been done, what remains t o be done, est imated t ime be fore repa i r , how i t a f f e c t s performance):

DURING THE CPE ( L i s t and exp la in ) :

DURING THE LAST 24 MONTHS ( L i s t and exp la in ) :

176

FORM D-5 (cont inued)

MAINTENANCE DATA

B. PREVENTIVE MAINTENANCE PROGRAM:

Method o f Scheduling:

Method o f Documenting Work Completed:

Adequacy o f Resources Ava i lab le :

Lubr icants :

Tool s :

Others :

C. EMERGENCY MAINTENANCE PROGRAM:

Small Spare Par ts ( fuses, b e l t s , bear ing, packing d i f f u s e r s , e t c ) :

Major Spare Par ts ( l a r g e motors, gear boxes, blowers, flowmeter, e t c .

Manpower:

Exper t ise:

References:

OW Manual :

Accurate As-Bui l ts:

Manufacturer 's L i t e r a t u r e :

177

FORM D-6 (continued)

PERFORMANCE DATA

B. REPORTED MONITORING DATA FOR PREVIOUS 12 MONTHS (cont. )

Mo/Y r

F i n a l E f f l u e n t

Flow BOD5 TSS

Other

AVG

1 80

FORM D-6

PERFORMANCE DATA

A. SOURCE OF DATA:

B. REPORTED i n mg/l ,

Mo/Y r F1 ow

MONITORING DATA FOR PREVIOUS 1 2 MONTHS ( f l o w s I n mgd; others except as noted):

80D5 TSS

Primary E f f l u e n t

BOD5 TSS

AVB

179

FORM D-5

MAINTENANCE DATA

D . GENERAL HOUSEKEEPING:

178

FORM D-6 (continued)

PERFORMANCE DATA

C . PERMIT PERFORMANCE VIOLATIONS WITHIN LAST 1 2 MONTHS (30-day averages, 7-day averages, Instantaneous violations, effluent mass violations, percent removal violations):

No. of Months Without a Violation

No. o f Months With a Violation

D . REASONS ( I f any) REPORTED MONITORING DATA ARE NOT BELIEVED TO REPRESENT ACTUAL EFFLUENT QUALITY (unrepresentative sampling, improper lab analyses, unaccounted-for sludge loss, selective reporting , etc . ) :

181

APPENDIX E

G U I D E L I N E S FOR F I E L D E S T I M A T I N G EQUIPMENT POWER USAGE

182

FIELD ESTIMATING EQUIPMENT POWER USAGE

The power a p a r t l c u l a r p iece o f equipment i s drawing can be est imated i n the f i e l d by measuring the cu r ren t being drawn by the motor. The measured power be ing drawn by a motor ( i n d u c t i v e user) i s "apparent power" and must be m u l t i p l i e d by the power f a c t o r (PF) t o c a l c u l a t e ac tua l power. Four methods are a v a i l a b l e t o a r r i v e a t a s u i t a b l e power f a c t o r :

1. Assume a power f a c t o r :

Use 0.9 f o r r e c e n t l y const ructed p lan ts t h a t l i k e l y inc luded use o f capac i to rs t o a d j u s t t he power f a c t o r toward 1.0. Use 0.75 f o r o l d and small p l a n t s where I t i s u n l i k e l y t h a t capac i to rs have been added.

2. Measure the "p lan t .power f a c t o r " us ing an ammeter and the p l a n t k i l owa t thou r meter and assume the power f a c t o r app l ies f o r l a r g e r pieces o f equipment. See Table E-1 f o r c a l c u l a t i o n worksheet. (WARNING: DO NOT USE THIS METHOD UNLESS QUALIFIED.)

3 . Ask the e l e c t r i c company t o measure the power f a c t o r o r ac tua l power usage o f s p e c i f i c equipment.

4 . Rent an appropr ia te inst rument and measure power f a c t o r o r ac tua l power usage. (WARNING: DO NOT USE THIS METHOD UNLESS QUALIFIED.)

Once the PF has been determined, the f o l l o w i n g c a l c u l a t i o n s can be used t o est imate power drawn by a p a r t l c u l a r p iece o f equipment:

Measure :

Average Voltage ( l i n e - t o - l i n e ) = Vo l t s

Average Amperage = Amps

Calcu late:

(3-phase power) V x A x 6 1000

kVA =

kW = kVA x PF

kW whp = - 0.746

183

TABLE E-1

WORKSHEET FOR CALCULATION OF POWER FACTOR

Atmarent Power

Llne-to-Line Voltage on Incoming Power:

V o l t s Vo l t s

V o l t s "2-3 '1 -3 v = Vo l t s a vg

- v1-2 - - -

- -

Amperage f o r Each Phase on Incoming Power:

Amps Amps

h P S

I = Amps

- I 1 - I2 - I 3 -

- -

a vg

Vo l t s x Amps x \/3 - kVA = - 1000

Actual Power

C T R ~

TR'

Kh

Disc

kW =

Power Fac tor

P f =

- - wat thours / revo lu t ion ( f rom meter)

- - P T R ~

= CTR x PTR = X

Speed = Seconds / Revolut ion(s)

Kh x TR x Disc Rev 3600 Sec 1 kW =

- -

Sec Hour 1000 Watts

- - - kW KVA

aCTR (Current Transformer Rat io ) - r a t i o of pr imary t o secondary cu r ren t . For cu r ren t t ransformer ra ted 200:5, r a t i o i s 200/5 o r 40/1.

bPTR ( P o t e n t i a l Transformer Rat io ) - r a t i o of pr imary t o secondary v o l t - age. For p o t e n t i a l t ransformer ra ted 480:120, r a t i o i s 480/120 o r 4/1.

'TR (Transformer Rat io ) - t o t a l r a t i o o f cu r ren t and p o t e n t i a l t rans- formers. f o r CTR = 200:5 and PTR = 480:120, TR = 40 x 4 = 160.

184

A P P E N D I X F

PROCEDURE FOR CONVERTING STANDARD OXYGENATION RATES T O ACTUAL OXYGENATION R A T E S

185

PROCEDURE FOR CONVERTING STANDARD OXYGENATION RATES ( S O R s ) TO ACTUAL OXYGENATION RATES (AORs)

Where:

AOR = ac tua l oxygen t r a n s f e r ra te , l b 02/hp-hr

SOR = standard oxygen t r a n s f e r ra te , . lb Oz/hp-hr ( f rom Table 3-3)

a = r e l a t i v e r a t e o f oxygen t r a n s f e r i n wastewater compared t o water. Est imate f rom Table F-1.

I3 = r e l a t i v e t o oxygen s a t u r a t i o n value i n wastewater compared

e = temperature c o r r e c t i o n constant, e = 1.024

t o water. Est imate I3 = 0.95 f o r mixed l i q u o r .

CS = oxygen s a t u r a t i o n value o f c lean water a t standard cond i t ions , Cs = 9.17 mg/l

Cs, = oxygen s a t u r a t i o n value of c lean water a t s i t e cond i t i ons o f temperature and pressure, mg/l

c~~ = c14.7 (L) 14.7

CL = mixed l i q u o r DO concentrat ions, mg/l

T = temperature o f t he l i q u i d , OC

c14.7 =

P = ac tua l pressure a t oxygen t r a n s f e r p o i n t

oxygen s a t u r a t i o n value o f c lean water a t standard pressure o f 14.7 p s i and ac tua l water temperature (see Table F-2).

a) For sur face aerators , use atmospheric pressure (see F igure F-1).

b) For o thers, use atmospheric pressure f rom F igure F-1 , p l u s t h e pressure a t mid-depth o f t h e tank f rom t h e sur face t o the d i f f u s e r s (1.e.. d i f f u s e r depth i n f e e t x 0.5 x 0.434 p s i / f t ) .

186

TABLE F-1

TYPICAL VALUES OF ALPHA (a) USED FOR ESTIMATING AOR/SOR

A e r a t i o n Device Typical

Course Bubble D i f f users 0.85

F i n e Bubble D i f f u s e r s 0.50

J e t A e r a t i o n 0.75

Surface Mechanical Aera tors 0.90

Submerged Turbines 0.85

187

TABLE F-2

OXYGEN SATURATION AT STANDARD PRESSURE AND ACTUAL WATER TEMPERATURE

Tempe r a t u r e ( " C )

0 1 2 3 4 5 6 7 8 9 10 1 1 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

D l ssol ved Oxygen S a t u r a t i o n Leve l

(m/l) 14.62 14.23 13.84 13.48 13.13 12.80 12.48 12.17 11.87 11.59 11.33 11.09 10.83 10.60 10.37 10.15 9.95 9.74 9.54 9.35 9.17 8.99 8.83 8.68 8.53 8.38 8.22 8.07 7.92 7.77 7.63

1 88

m

w

3

n

m .I

0

U

CT 5

-I

>

I

0

CT W

I

m

0

E

I- <

CI

a

+

a

a

+

cc 0

v)

? 0 2

189

APPENDIX G

EXAMPLE FORMS FOR ESTABLISHING A PREVENTIVE MAINTENANCE PROGRAM FOR SMALL POTWs

- Form T i t l e

6-1 Equipment Information Sheet 6-2 D a i l y Preventive Maintenance 6-3 6-4 Monthly Preventive Maintenance

Weekly Prevent 1 ve Mal ntenance

190

FORM G-1

EQUIPMENT INFORMATION SHEET

P lan t Equipment Number

Locat i o n O r i g i n a l I n s t a l l a t i o n Date

Manuf ac t u r e r Model S e r i a l No;

Type Rated Capacity Rated Pressure o r Head

Add i t i ona l Data

[D"IVEI Type Manufacturer

Desc r i p t i on

-1 Manufacturer HP R PM

Frame Enclosure Type S.F.

Type Rated Amperage Rated Voltage

SUPPLIER(S):

ComDanv Name & Address Lontac t Person Telephone No.

Additional In fo rmat ion and Comnents:

-

191

FORM G-1 (continued)

EQUIPMENT INFORMATION SHEET

RECOMMENDED PREVENTIVE MAINTENANCE:

- F r e q u e n c y

RECOMMENDED LUBRICANTS: - P a r t L u b r i c a n t Name & D e s c r i D t i o n S o u r c e

RECOMMENDED SPARE PARTS: P a r t Desc r i D t i o n Number O u a n t 1 t y

192

FORM 6-2

DAILY PREVENTIVE MAINTENANCE

TIME INITIALS Inlet Building

- Check operation of grit pump, cyclone, a.m. grit bin, pump seal water pressure p.m.

(psi), leakage (drops/min).

- Check grit collector for unusual noise a ,m. or torque. p.m.

- Check flow meter operation, chain, float, a.m. stilling well. p.m.

- Check auto sampler operation and bottle a.m. installation. p.m.

Grit' SeDarator #2 Building

- Check for unusual noise or vibration in collector or conveyor.

Primary Clarifier

- Check for unusual noise or vibration in drive unit.

a.m. p.m.

a.m. p.m.

Aeration Buildinq

- Check blowers for unusual noise or a.m. vi brat i on. p.m.

Temoerature: ;ki Inlet OC Outlet OC #2 Inlet OC Outlet OC #3 Inlet OC Outlet OC

- Check auto sampler operation and bottle a.m. Installation. p.m.

(Form continued to include all process units and buildings requiring da i ly mi ntenance .)

193

FORM 6-3

WEEKLY PREVENTIVE MAINTENANCE

I n l e t B u i l d i n g

G r i t #l C o l l e c t o r Dr ive: Apply grease t o upper and lower bear ings i n worm gear housing.

G r i t #1 C o l l e c t o r Dr ive: Check o i l l e v e l i n gear housing; remove condensate i n gear d r i v e .

G r i t #1 C o l l e c t o r Dr ive: Lubr ica te chain between d r i v e u n i t and motor gear.

G r i t #l C o l l e c t o r Dr ive: Check torque over load alarm f o r proper operat ion.

Communitor: Check o i l l e v e l i n main gear box ( lower) .

Communitor: Check o i l l e v e l i n motor gear u n i t .

Automatic Sampler: tube and s t r a i n e r .

Remove and c lean sampling

G r i t SeDarator #2 B u i l d i n g

- G r i t #2 Dr ive U n i t : Check o i l l e v e l i n Ph i lade lph ia gear reducer.

- G r i t #2 Conveyor Un i t : Apply grease t o a l l bear ings o f chain d r i v e and support sprockets.

- G r i t #2 Conveyor Unit: Check o i l l e v e l i n conveyor d r i v e reducer.

Aerat ion B u i l d i n g

- Automatic Sampler: Remove and c lean sampling tube and s t r a i n e r .

- Aerat ion Blowers: Check o i l l e v e l - 3 p o i n t s (gears, two bear ings)

- Aera t ion Blowers: Operate b lower(s) (10 min each) n o t i n serv ice. Check o i l l e v e l and temperature.

DATE I N I T I A L S

(Form cont inued t o i nc lude a l l process u n i t s and b u i l d i n g s r e q u i r i n g weekly maintenance.)

194

I

FORM 6-4

MONTHLY PREVENTIVE MAINTENANCE

DATE INITIALS

I n l e t B u i l d i n g

- Automatic Sampler: Check pump tub ing f o r - signs o f f a i l u r e . t o inspect .

Remove from pump housing

G r i t SeDarator #2 B u i l d i n g

- Gear Reducer: Apply grease t o upper and lower bear ings.

Primary C l a r i f i e r

- a Dr ive Mechanism: Check gear l u b r i c a t i o n ( d i p s t i c k ) . Check base p l a t e l u b r i c a t i o n ( o i l cap)

- Gear Reducer: Apply grease t o upper, lower, and two s ide bear ings.

(Form cont lnued t o i nc lude a l l process u n i t s and b u i l d i n g s r e q u i r i n g month 1 y ma i n t enance . )

Porvide S i m i l a r Forms For:

QUARTERLY PREVENTIVE MAINTENANCE SEMIANNUAL PREVENTIVE MAINTENANCE ANNUAL PREVENTIVE MAINTENANCE

195

APPENDIX H

DESIGN-RELATED PERFORMANCE-LIMITING FACTORS I D E N T I F I E D I N ACTUAL CPEs

196

DESIGN-RELATE0 PERFORMANCE-LIMITING FACTORS

The design problems l i s t e d i n t h i s appendix were i d e n t i f i e d du r ing a c t u a l comprehensive performance evaluat ions. Most o f these problems have resu l ted I n unnecessary o r excessive maintenance, d i f f i c u l t process c o n t r o l , inaccura te o r excessive sampling, and poor POTW performance.

These des ign-re la ted problems a re discussed I n the contex t of t he f o l l o w i n g categor ies:

P lan t Layout Secondary C l a r i f i e r s

Flow Measurement Return Sludge Flows

Bar Screens Po l i sh ing Ponds

Commi nu tors

G r i t Removal

Primary C l a r i f i e r s

Aera t ion Basins

Aerators

T r i ck1 i n g F i l t e r s

ABF Towers

RBCs

Ch 1 o r1 na t 1 on

Wasting C a p a b i l i t y

Sludge Hold ing F a c i l i t i e s

Aerobic Digesters

Anaerobi c D i ges t e r s

Sludge Dewatering 8 Ul t ima te Disposal

Laboratory F a c i l i t i e s

Miscellaneous

197

Plant Layout

- I n d i v i d u a l process t r a i n s , w i thou t in te rconnect ion , r e q u i r e opera t ion o f u n i t s as i f th ree separate a c t i v a t e d sludge p l a n t s e x i s t a t one POTW r a t h e r than j u s t one

- Covered basins w i thou t adequate observat ion access prevent observat ion o f processes

- Return sludge a i r compressors a re loca ted ou ts ide and repeatedly break down

- No f l o w s p l i t t i n g f l e x i b i l i t y t o p a r a l l e l u n i t s

- Bar screen loca ted downstream from comminutor

- Freezing o f i n f l u e n t sampler loca ted ou ts ide

- P lan t l o c a t i o n inaccess ib le du r ing inclement weather

- Excessive compressor no ise

- D i s i n f e c t i o n before p o l i s h i n g pond

- P a r a l l e l secondary t reatment u n i t s n o t capable o f be ing operated as one f a c i l i t y

- Inadequate p i p i n g f l e x i b i l i t y requ i res shutdown o f one t r i c k l i n g f i l t e r i f one c l a r i f i e r i s down

- One scraper d r i v e f o r pr imary and f i n a l c l a r i f i e r s requ i res shutdown o f both f o r maintenance on e i t h e r

- Lack o f bypasses on i n d i v i d u a l t reatment u n i t s such as a e r a t i o n basins, t r i c k l i n g f i l t e r s , c h l o r i n e contac t basins, e t c .

- Use o f a s e p t i c tank f o r i n p l a n t domestic and labo ra to ry wastes and over f low from t h e sep t i c tank t o t h e p l a n t e f f l u e n t

- Both t r i c k l i n g f i l t e r and a c t i v a t e d sludge processes i n very smal l p l a n t causes excessive opera t iona l requirements

Flow Measurement

- Discharge through a p ipe r a t h e r than the c o n t r o l sec t i on f o r which the recorder I s appropr ia te

- Downstream channel s lope and geometry causes backup i n P.arsha11 flume t h r o a t

198

- Parsha l l f lume overs ized

- Flow measurement inaccurate due t o upstream barminutor placement

- No f l o w recorder

- Excessive upstream v e l o c i t y causes t u r b u l e n t f l o w through Parsha l l f lume

- Cont ro l sec t i on no t access ib le f o r i nspec t i on and maintenance

- Level t r a n s m i t t i n g ins t rumenta t ion n o t compat ib le w i t h l e v e l rece iv ing ins t rumenta t ion

- Parsha l l f lume on POTW e f f l u e n t submerged du r ing h igh r i v e r f lows

- Recycle f lows ( c o o l i n g water) Inc luded .in p l a n t f l o w measurement

- Ro l lup f l o w c h a r t requ i res removal t o observe f l o w f o r more than

- Wires crossed i n t o t a l i z e r , r e s u l t i n g i n wrong reading

t h e preceding 4 hours

- Humid i n f l u e n t s t r u c t u r e causes problem w i t h mo is tu re-sens i t i ve l e v e l sensor

- Flow v e l o c i t y t o o h igh i n Kennison nqzz le

- L i q u i d l e v e l sensing f l o a t f reezes

- Downstream bar screen backs f l o w i n t o flume t h r o a t as screen p lugs

Bar Screens

- Bar spacing too narrow and causes excessive b l i n d i n g

- Backed-up f l o w released a f t e r c lean ing causes hyd rau l i c surges through ae ra t i on bas in and i n t o c l a r i f i e r

- Freezing problems w i t h mechanical bar screen loca ted ou ts ide

Commi nu tors

- Repeated mechanical f a i l u r e o f hyd rau l i c dr ive- type c o m i n u t o r

199

G r i t Removal

- Excess wear on g r i t screw center bear ing because o f exposure t o g r i t

- Odors from organics s e t t l i n g ou t i n overs ized g r i t channel

- Pump discharge t o g r i t chamber d i r e c t e d a t g r i t buckets, and washes g r i t f rom buckets

- G r i t auger n o t f u n c t i o n a l

- G r i t auger discharges too low f o r d isposal i n t r u c k

Primary C l a r i f i e r s

- Overloaded by excess ive ly l a r g e t r i c k l i n g f i l t e r humus r e t u r n pump

- Overload due t o t r i c k l i n g f i l t e r r e c i r c u l a t i o n designed t o rou te through pr imary c l a r i f i e r

- Improper placement o f va lve l i m i t s scum pumping

- S h o r t - c i r c u i t i n g due t o i n l e t b a f f l e cons t ruc t i on

- Preaerat ion i n center o f c l a r i f i e r reduces e f f e c t i v e c l a r i f i - c a t i o n area

Aerat ion Basins

\ - Pipe o u t l e t p lugs w i t h rags

- Lack o f p i p i n g t o operate as conventfonal as w e l l as step-load o r c o n t a c t - s t a b i l i z a t i o n a c t i v a t e d sludge

- Receives hyd rau l i c surges when the bar screen i s cleaned and from overs ized r e t u r n pump on t imeclock

- Loss o f s o l i d s caused by f l o o d i n g due t o ae ra t i on bas in des ign e leva t i on and lack o f drainage c o n t r o l

- Act ion o f ae ra t i on r o t o r s and r e v o l v i n g b r idge and c o n f i g u r a t i o n o f bas in creates swe l ls and vo ids t h a t r e s u l t i n wavel ike s t resses on b r idge

- Leakage between contac t and reae ra t i on basins o f con tac t

- No w a l l between contac t and reae ra t i on areas o f con tac t

s t a b i l l z a t l o n p l a n t due t o movable w a l l design

s t a b i l i z a t i o n p l a n t

200

Aerators

- Inadequate capac i ty f o r oxygen t r a n s f e r

- Surface mechanical aera tors overheat and shut o f f under increased flows due t o i n f i l t r a t i o n / i n f l o w

- Inadequate DO c o n t r o l because blowers prov ided a re t o o l a r g e

- With f l o a t i n g aerators , repeated break ing o f cables when operated on i n t e r m i t t e n t bas is

- With submerged t u r b i n e aerators , repeated downtime due t o bear ing and s h a f t f a i l u r e

- Surface aera tors t h a t do no t p rov ide adequate bottom mix ing i n a deep o x i d a t l o n d i t c h

- Inadequate f reeboard f o r sp lashing w i t h sur face mechanical

- Brush aera tors provided i n co ld c l ima te w i thou t I c e p r o t e c t i o n

aera tors

- I c i n g problems w i t h sur face mechanical aera tors

- Rag accumulation on sur face mechanical aera tors

- Inadequate DO c o n t r o l

T r i ck1 i n n F i 1 t e r s

- Rec i r cu la t i on on ly through pr imary c l a r i f i e r

- Inadequate capac i ty o f t r i c k l i n g f i l t e r arms

- Poor f l ow s p l i t t i n g t o t r i c k l i n g f i l t e r s

ABF Tower

- Inadequately s ized f o r organic load

- Undersized p i p e c a r r y i n g tower underf low back t o r e c i r c u l a t i o n tank

- No f l e x i b i l i t y t o vary percent tower under f low returned t o r e c i r c u l a t i o n tank

- Sludge r e t u r n and tower recyc le f l o w a r e d i r e c t e d I n t o the same pipe, which l i m i t s t h e i r volume recyc led

- No f l o w measurement on d i r e c t recyc le f l o w around tower

201

Po l l sh ins Ponds

- No pond bypass

- Sludge wasted t o p o l i s h i n g pond

- Pond located a f t e r d i s i n f e c t i o n

Ch lo r i n a t i on

- Chlor ine d i f f u s e r loca ted a t cen ter o f con tac t tank r a t h e r than a t i n l e t

- Ch lor ine d i f f u s e r loca ted a t o u t l e t o f con tac t tank

- S ing le contact tank p r o h i b i t s d i s i n f e c t i o n du r ing c lean ing and discourages c lean ing o f con tac t bas in

- Rotometer on c h l o r i n a t o r t oo l a r g e f o r present a p p l i c a t i o n

- Poor mix ing

- Chlor ine dosage paced by e f f l u e n t f low, bu t f i l t e r backwash water removed from combined contact-backwash storage tank shuts o f f c h l o r i n a t i o n u n t i l i t i s again f i l l e d and d ischarg ing

- Inadequate c h l o r i n e contac t t ime i n o u t f a l l p ipe

- No depth c o n t r o l dev ice on contac t tank r e s u l t s i n inadequate contac t t i m e and s h o r t - c i r c u i t i n g

- S h o r t - c i r c u i t i n g over b a f f l e s du r ing h igh f lows

- S h o r t - c i r c u i t i n g due t o i n l e t design

Wastins C a p a b i l i t v

- No d i g e s t e r o r sludge ho ld ing f a c i l i t y ; inadequate d r y i n g beds

- Downtime o f e x o t i c sludge t reatment f a c i l i t y causes inadequate wast ing

- Wasting c a p a b i l i t y o n l y f rom mixed l i q u o r requ i res excessive waste volume

- I n s u f f i c i e n t wast ing capac i ty

- Sludge lagoons undersized

204

Return Sludge Flows

- Constant-speed c e n t r i f u g a l pumps make i t d , i f f i c u l t t o a d j u s t f l o w

- Oversized constant-speed pumps provided

- Return sludge f l o w no t v i s i b l e

- No measurement

- S ing le pump r e t u r n i n g from mu f l o w d i f f i c u l t

a t any p o i n t

t i p l e c l a r i f i e r s ; ba lanc ing r e t u r n

- Variable-speed r e t u r n pumps too l a r g e even a t lowest s e t t i n g

- Plugging o f te lescop ing valves a t lower f lows

- Sludge returned t o a p o i n t near the o u t l e t o f t he ae ra t i on bas in

- Not access ib le f o r sampling

- P ip ing p r o h l b l t s r e t u r n sludge f l o w f o r severa l hours w h i l e

- Measurement w i t h 900 V-notch w e i r n o t s e n s i t i v e enough f o r

sludge i s be ing removed from the aerobic d i g e s t e r

needed f l o w adjustments

- Oversized pump on t imeclock draws down f i n a l c l a r i f i e r , then h y d r a u l i c a l l y overloads ae ra t i on bas in

- Waste p i p i n g and appurtenances r e q u i r e excess r e t u r n r a t e t o accomplish wast ing

- S t i l l i n g box ahead o f V-notch w e i r t o o small

- Locat ion o f r e t u r n measurement requ i res opera tor t o walk ou t on narrow w a l l over basins, r e s u l t i n g i n unsafe working cond i t i ons

- Sludge r e t u r n f rom c l a r i f i e r s c o n t r o l l e d by p lug va lve i n t o wet we1 1 Excess operator t ime requ i red t o match variable-speed pump w i t h va lve-cont ro l led r a t e

- Return adjustment requ i res a l t e r n a t e opera t ion o f pump from f i r s t c l a r i f i e r , second c l a r i f i e r , and both c l a r i f i e r s t o s e t des i red t o t a l r e t u r n

- P a r t i a l p lugging w i t h rags o f b u t t e r f l y va lve used f o r r e t u r n sludge f l o w c o n t r o l

~ - Rapid wi thdrawal sludge removal designed w i thou t sampling o r adjustment c a p a b i l i t y from var ious p o r t s

203

RBCs - No p o s i t i v e f l o w s p l i t t i n g t o var ious t r a i n s

- No access provided through covers t o take d isso lved oxygen measurements

- Inadequate s h a f t design causes excessive downtime

Secondary C l a r i f i e r s

- Poor f l o w s p l i t t i n g t o c l a r i f i e r s

- Poor development o f sur face area w i t h wei rs

- Sludge scraper mechanism d i r e c t i n g contercur ren t t o wastewater f l o w

- H y d r a u l i c a l l y connected c l a r i f i e r s no t o f t h e same e l e v a t i o n causes unequal f l o w s p l i t t i n g

- Freezing du r ing c o l d weather

- I n l e t and o u t l e t on circumference, a l a r g e diameter, a l a r g e design over f low ra te , and f a i l u r e t o consider process recyc le f lows cause problems w i t h hyd rau l i c washout o f s o l i d s

- Scum returned t o ae ra t i on basin; no u l t i m a t e d isposal o f scum

- Combined pr imary and f i n a l c l a r i f i e r u n i t a l lows mix ing o f two with scraper mechanism

- Hydraul ic r e s t r i c t i o n causes submerged over f low we i rs

- S h o r t - c i r c u i t i n g due t o i n l e t b a f f l e cons t ruc t i on

- Placement o f t r i c k l i n g f i l t e r r e c i r c u l a t i o n drawoff over loads f i n a l c l a r i f i e r

- Weirs on s i n g l e launder n o t balanced t o p u l l evenly f rom each s ide

- No skimming dev ice

- Shallow depth promotes t h i n underf low concentrat ions and s o l i d s washout

202

- No waste f l o w measurement

- P a r t i a l p lugging o f waste pump prevents use o f pumping r a t e t o c a l c u l a t e waste volume

- Valve choice f o r d i r e c t i n g r e t u r n sludge t o waste requ i res excess operator t i me

- Undersized waste pump

Sludge Hold ing F a c i l i t i e s

- Odors from unaerated, uncovered sludge storage

- Undersized storage capac i ty g iven u l t i m a t e sludge d isposal l i m i t a t i o n s

- Po ten t ia l gas bu i ldup problem w i t h covered, unaerated sludge storage

Aerobic Diaesters

- High groundwater and pressure r e l i e f va lve prevents batch operat i on

- Inadequate a i r supply

- Inadequate supernat ing c a p a b i l i t y

- Undersized

- Pump used f o r sludge removal prevents th i cken ing o f sludge

- Small d iges te rs and minimum freeboard make foam containment d i f f i c u l t

- Freezing problems

- Common w a l l w i t h ae ra t i on bas in s t r u c t u r a l l y i n s u f f i c i e n t t o a l l o w batch opera t ion

- Provided w i t h "automat ic" supernat ing dev ice t h a t cannot work

Anae rob 1 c D i ses t e r s

- Inadequate supernatant drawof fs

- With m u l t i p l e u n i t s , i n f l e x i b i l i t y t o waste t o des i red pr imary d i g e s t e r

205

A P P E N D I X I

EXAMPLE PROCESS M O N I T O R I N G SUMMARY FOR AN A C T I V A T E D SLUDGE POTW

208

Miscel laneous

- S t a b i l i z a t i o n o f sludge w i t h c h l o r i n e re leases heavy meta ls t o recyc led supernatant

- Wooden gates i n f l o w d l v e r s i o n s t r u c t u r e swel l and cannot be removed

- No automatic r e s t a r t a f t e r power outage

- B u t t e r f l y va lve used between mixed l i q u o r and f i n a l e f f l u e n t leaks mixed l i q u o r i n t o e f f l u e n t

- Undersized raw l i f t pumps

207

- Plugging problem between bottom o f pr imary d i g e s t e r and second-stage d iges te r

- Water seal on sludge r e c i r c u l a t i o n pump loads d i g e s t e r w i t h c o l d water

- Sludge pumping l i n e f rom c l a r i f i e r p lugs prevents d i g e s t e r load lng a t concentrat ions above about 6 percent

- No gas meters

- No mix ing

- Cold d i g e s t e r produces poor supernatant q u a l i t y and poor d i g e s t i o n

- S ing le gas meter f o r two d iges te rs

- Uninsulated heat ing p ipes ou ts ide

Sludqe Dewaterinq & U l t imate DisDosal

- Truck ramp t o o steep f o r use du r ing w i n t e r

- Excessive maintenance on sludge i n c i n e r a t i o n f a c i l i t i e s

- I n s u f f i c i e n t sludge d r y i n g lagoons

- Disposal o f sludge i n p o l i s h i n g lagoon

- Truck capac i ty t o o smal l f o r sludge produced

- I n s u f f i c i e n t d r y i n g beds f o r wet o r c o l d weather opera t ion

- Land a p p l i c a t i o n no t poss ib le du r ing c e r t a i n t imes o f t h e year; no a l t e r n a t e d isposa l o r storage

Laboratory F a c i l i t i e s

- V ib ra t i ons prevent use o f sca le

- Inadequately equipped

- Humidi ty d i f f i c u l t t o work i n and hard on equipment

- Noise f rom blowers l i m i t s u s a b i l i t y

- Poor l i g h t i n g

- I n s u f f i c i e n t f l o o r space

206

DAILY CONTROL CALCULATION SHEET FOR AN ACTIVATED SLUDGE P O T W ~

Aerator Volume (AV) = m Clarifier Depth (CD) = , m Clarifier Volume (CV) = m Clarifier Surface Area ( E A ) = Mont hNear m Location

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 DATE ATC RSC CSC DTB TURB FLOW RSF RFP RSP ASU CSU SDR TSU ESU XSU WSU MCRT RSU SOT, SOT, SDT,xATC CSL OFR S S C s S S C B o

( O h ) (Oh) (Oh) (m) (NTU) (m31d) (&Id) ( O h ) (Oh) (m3x%) ( m 3 x % ) (ASUICSU) ( m 3 x % ) ( m 3 x % ) (m3x%) ( m 3 x % ) (d) ( m 3 x % ) (hr) (hr) ( h r x % ) (units/m*) (m31m21d) ( % ) ( % I 1

2

3

4

5 6

7

8

9

i n

1 1

1 2

1 3

1 4

1 5

1 6

1 7

1 8

1 9

2 0

2 2

2 4 2 5

2 6 77

2 8

3 1

TOTAL

f o l 1 owing f o r an exp lana t ion o f on t h i s

COLUMN I N F O R M A T I O N FOR D A I L Y CONTROL C A L C U L A T I O N S H E E T

Co I umn

I

2

3

4

-* . -

5

6

7

8

9

svmbol

DATE

ATC

RSC

csc

DTB

TURB

FLOW

RSF

RFP

Svmbol Meaning

Self-Explanatory

Aeration Tank Concentration

Return Sludge Concentration

C l a r i f i e r Sludge Concentration

Depth t o (Sludge) Blanket

Turbi d i t y

Dai l y Wastewater Flow

Return Sludge Flow

Return S I udge F I ow Percentage

Explanation

Average of values recorded during the day on the Dai ly Data Sheet.

Average of values recorded during the day on the Dai ly Data Sheet.

Average concentration of sludge w i th in the c l a r i f i e r as determined from a core sanple (Method I ) or by ca lcu lat ion (Method 2).

Method I. Core Sample - average o f values recorded during the day on the Dai l y Data Sheet.

Method 2. Calculat ion - average o f ATC and Rsc.

ATC + RSC

2 csc=

Average o f values recorded during the day on the Dai ly Data Sheet.

Average o f values recorded during the day on the Dai l y Data Sheet.

Total wastewater f l o w f o r a given 24-hour t i m e period (e.g., 8:OO a.m. t o 8:OO a.m.).

Total d a i l y re turn sludge f l ow . (Note: Time period f o r determining t h i s ra te should be the same as the time period used f o r detennining dai l y wastewater f l o w ra te Ce.g., 8:OO a.m. t o 8 :OO a.m.3)

Return sludge f l o w divided by averaQe dai ly wastewater f low.

RSF RFP = - x 100%

FLW

21 0

COLUMN I N F O R M A T I O N FOR D A I L Y CONTROL C A L C U L A T I O N S H E E T (continued)

Column Svmbal Symbol Meaning Explanation

I O RSP Return Sludge Percentage Return sludge flow percentage based on mass balance.

I I ASU Aerator Sludge Units

12 csu Clarifier Sludge Units

-* . .

Total aeration tank volume (AV) times ATC.

ASU = (AV)(ATC)

Method I . Core Sample - clarifier sludge concentration times the clarifier volume (CV) .

Method 2. Calculation - clarifier sludge concentration times the fraction of the clarifier filled with sludge, times the clarifier volume (CV).

csu = (CSC) - (CV) CD

13 SDR Sludge Distribution Ratio Ratio of the quantity of solids under aeration vs the quantity of solids in the clari f ier.

ASU SDR = -

CSU

14 TSU Total Sludge Units

15 ESU Effluent Sludge Units

TSU = ASU + CSU

Quantity of sludge lost in the effluent each day.

ESU = Effluent suspended solids (TSS) times FLOW divided by ratio of MLSS to percent solids by centrifuge (e.g., ratio = MLSS divided by ATC).

(TSS) (FLOW)

Ratio ESU =

21 1

COLUMN I N F O R M A T I O N FOR D A I L Y CONTROL C A L C U L A T I O N S H E E T (continued)

co I umn

16

17

18

*. . .

19

20

21

22

23

svmbol

xsu

WSU

MCRT

RSU

SDTA

SDTc

SDTA x ATC

CSL

Symbol Meaning

Intentionally Wasted Sludge Units

Tota I Waste S I udge Un i ts

Mean Cel I Residence Time

Return Sludge Units

Sludge Detention Time in the Aerator

Sludge Detention Time in the Clarifier

See meanings above

Clarifier Solids Loading

Explanation

Quantity of Sludge intentionally wasted from the system each day = average concentrat i on of wasted s I udge times the volume of sludge wasted (fran the Daily Data Sheet).

WSU = ESU + XSU

Average of n h r of s I udge rema i ns

TSU HCRT = -

of days a given quantity in the system.

WSU Return sludge flow rate times the return sludge concentration.

Average number of hours a given quantity of sludge ramain in the aerator.

(AV) (24 hr/d)

FLOW + RSF SDTA =

Average length of time a given quantity of sludge remains in the clarifier.

(CSU) (24 hr/d)

RSU SDTc =

Indication of the treatment pressure in the system.

Average daily mass of sludge to the clarifier divided by the clarifier surface area (CSAI.

(FLOW + RSF)(ATC) CSA

CSL =

21 2

COLUMN INFORMATION FOR DAILY CONTROL CALCULATION SHEET (continued)

column Svmbol

24 OFR

25 s=5

26 ssc,

Svmbol Meaning

C l a r i f i e r Surface Overflow Rate

Set t led Sludge Concentration i n 5 minutes

Set t led Sludge Concentration i n 60 minutes

ExD I anat ion

Upward ve loc i ty o f the t reated wastewater i n the secondary c l a r i f i e r .

FLOY OFR = -

CSA Average of values recorded during the day on the Dai ly Data Sheet.

Average o f values recorded during the day on the Dai l y Data Sheet.

r. .

21 3

c. . .

A P P E N D I X J

EXAMPLE PROCESS M O N I T O R I N G SUMMARY FOR AN RBC POTW

21 4

EXAMPLE RBC PROCESS MONITORING SUMMARY*

Week o f 19- Date

Day

Flow, mgd

INFLUENT BOD, mg/l

SBOD, mg/l

TSS, mg/l

pH, u n i t s

Temp., OC

WET WELL

SBOD5 mg/l

Sun Mon Tues Wed Thurs F r i Sat

P R I M A R Y CLARIFIER

DTB,* m - - Avg - BOD5, mg/l

TSS, mg/l

pH, u n i t s

Temp., C

SBOD5, mg/l --

0

SECONDARY CLARIFIERS

DTB1, m Avg - DTB2, m Avg - BOD5, mg/l Avg - SBOD5, mg/l

*Explanat ion prov ided a t t h e end o f Appendix 3 .

21 5

EXAMPLE RBC PROCESS M O N I T O R I N G SUMMARY (cont inued)

Date

Day

Week o f 19-

-- -- Sun Mon Tues Wed Thurs F r i Sat

CHLORINE CONTACT EFFLUENT

C 1 2 Res, mg/l Avg - Fecal Col i form, GM*

MPN/1 pH, u n i t s

TSS, mg/l

O&G,* mg/l

SECONDARY SLUDGE

min/d pumped

c- .

1 /s 3 m /d

sp in.* -%

r a t i o * mg/l

kg/d

PRIMARY SLUDGE

S t a r t Time

End Time

Minutes 3 m /d 3 m

spin, %

r a t i o

mg/l

kg/d

Ava

Ava I.. J

21 6

EXAMPLE RBC PROCESS MONITORING SUMMARY (cont inued)

RBC DISSOLVED OXYGEN

(Date T i me 1 RBC TRAIN PERFORMANCE

(Date T i me 1

T r a i n 1 T r a i n 2 T r a i n 3 SBOD5

Stage 1

Stage 2

Stage 3

Stage 4

T r a i n 1 mg/l

T r a i n 2 mg/l

T r a i n 3 Wl

RBC EFFLUENT

(Date Time )

DO mg/l TSS mg/l pH Temp "C

20

18

16

14

12

10

8

6

4

2

0 5 10 15

Time, min

20 25 30

21 7

EXAMPLE RBC PROCESS MONITORING SUMMARY (cont inued)

Term Explanat ion -

DTB Depth t o (Sludge) Blanket

GM Geometri c Mean

O&G O i l and Grease

S P I N Concentrat ion; percent o f sample volume t h e compacted sludge occupies a f t e r a 15-minute l abo ra to ry c e n t r i f u g e sp in

RAT I O MLSS d i v i d e d by ATC (see Appendix I, Column In fo rma t ion f o r D a i l y Cont ro l Ca lcu la t i on Sheet)

c. . .

21 8

c. .

A P P E N D I X K

PARAMETERS USED T O MONITOR THE ABF TREATMENT PROCESS

21 9

PARAMETERS USED TO MONITOR THE A B F TREATMENT PROCESS

eo I umn

I

2

3

4

5 c- .

6

7

8

9

IO

svmbol

DATE

ATC

Rsc

csc

DT8

TURB

FLOW

RSF

RFP

BCRF

S&l Meaning

Self-Explanatory

Aeration Tank Concentration

Return Sludge Concentration

C I a r i f i e r S I udge Concentration

Depth t o (Sludge) Blanket

Turbi d i ty

Dai ly Wastewater Flow

Return Sludge Flow

Return Sludge Flow Percentage

Biocel I Di rec t Recirculat ion Flow

Explanation

Average o f values recorded during the day on the Dai l y Data Sheet.

Average o f values recorded during the day on the Dai ly Data Sheet.

Average concentration o f sludge w i th in the c l a r i f i e r . Average o f values recorded during the day on the Dai ly Data Sheet.

Average o f values recorded during the day on the Dai ly Data Sheet.

Average o f values recorded during the day on the Dai l y Data Sheet.

Wastewater f l o w for a given 24-hour t i m e period (e.g., 8:OO am. t o 8:OO a.m.).

Total d a i l y return sludge f low. (Note: Time period f o r determining t h i s ra te should be the same as the time period used fo r determining dai ly wastewater f l o w ra te Ce.g., 8:OO a.m. t o 8:OO a.m.1)

Return sludge f l o w divided by average dai l y wastewater f low.

RSF

FLOW RFP = - x IOOX

Dai ly t o t a l f l o w from the b ioce l l under drain d i r e c t l y t o the rec i rcu la t ion wet w e l l . (Note: Time period f o r determining t h i s f l o w should be the same as f o r determining the average dai l y wastewater flow.)

*A Dally Control Calculation Sheet similar t o the one presented for ac- tivated sludge I n Appendlx I can be used t o present these parameters in tabular form.

220

C O l U m

I I

12

svmbol

BCRFP

TFBC

PARAMETERS USED TO MONITOR THE ABF TREATMENT PROCESS (cont inued)

Svmbol Meaning

Biocel I D i rec t Recirculat ion Flow Percentage

Total Flow t o the Biocel l

13 BCHL Biocel l Hydraulic Load r- .

14 ASU Aerator Sludge Units

15 CSU C l a r i f i e r Sludge Units

16

17

18

19

TVBC

BCSU

TSU

Sm

Total Volume i n the Biocel l

Biocel l Sludge Units

Total Sludge Units

Sludge D is t r ibu t ion Ratio

Explanation

Percentage expression o f the r a t i o o f the volume o f d i r e c t b ioce l l rec i rcu la t ion t o the volune o f raw wastewater.

BCRF BCRFP = - x 1-

FLW

Total volume o f l i q u i d pumped t o the biocel I.

TFBC = FLOW + RSF + BCRF

Volume o f l i q u i d pumped t o the b ioce l l per u n i t area o f b ioce l l i n operation.

TFBC x 6% Biocel l Surface Area

Total aerator volune (AV) times ATC.

ASU = AV x ATC

C l a r i f i e r volume (CV) times c l a r i f i e r sludge concentration.

csu = cv x csc

Volume o f mixed l iquor i n the b ioce l l and associated appurtenances. TVBC = volume i n tower, volune i n underdrain, volune i n recirculat ion, and volume i n tower piping.

BCSU = TVBC x ATC

TSU = ASU + BCSU + CSU

Ratio o f the mass o f sol ids i n the aeration tank + mass o f sludge i n the b ioce l l t o the mass of sludge i n the f i n a l c l a r i f i e r .

ASU + BCSU CSU

sm =

22 1

PARAMETERS USED TO MONITOK THE ABF TREATMENT PROCESS (continued)

Column Symbol Symbol Meaning

20 ESU Effluent Sludge Units

21 xsu Intentionally Wasted Sludge Units

22 WSU Tota I Waste S I udge Units

23 HCRT Mean Cell Residence Time

24 RSU Return Sludge Units

25 SDTA Sludge Detention Time in the Aerator

26 SOT= Sludge Detention Time in the Biocel I

Explanation

Quantity of sludge lost in the effluent each day.

(TSS) (FLOW)

Ratio ESU =

MISS Ratio = - ATC

Quantity of Sludge intentionally wasted from the system each day = average concentration of wasted sludge times the volume of sludge wasted (from the Daily Data Sheet).

WSU = ESU + XSU

Indication of sludge age or the "mean time an average sludge cel I is in residence in the system."

TSU H C R T = - xsu Return sludge flow rate times the return sludge concentration.

Average length of time in hours a given quantity of sludge remains in the aerator.

AV x 24 hr/d SDTA = TFBC - BCRF

Indication of the length of the time in hours the suspended growth sludge spends in the biocell and associated appurtenances, equal to the hydrau I ic detention time.

TVBC SOT% = - TFBC

222

a

column Symbol

27 SDTc

28 TDT

29 CYCLES

30 SDTA x ATC

31 CSL

. 32 OFR

33 ssc5

34 sscm

35 sscm

36 sv I

PARAMETERS u s E e TO MONITOR THE A B F TREATMENT PROCESS (continued)

Symbol Meaning

Sludge Detention Time i n the C l a r i f i e r s

Total Detention Time

Sludge Cycles per Day

See meanings above

C l a r i f i e r Solids Loading

C l a r i f i e r Overflow Rate

Set t led Sludge Concentration i n 5 minutes

Set t led Sludge Concentration i n 30 minutes

Set t led Sludge Concentration i n 60 minutes

Sludge Volume Index

Explanation

Average length o f t i m e the sludge remains i n the c l a r i f i e r s during each pass around the system.

csu SDTc = - RSU

TDT = SDTA + SOTw + SDTc

Number o f times the sludge cycles through the en t i re system during the day.

24 hr /d CYCLES = ~

TDT

Indicat ion o f the treaiment pressure i n the system.

Indicates the mass loading o f sol ids on the f i n a l c l a r i f i e r s .

ATC (TFBC - BCRF) CSL =

CSA

Indicat ion o f the hydraul ic upflow ra te i n the f i n a l c l a r i f i e r s .

FLOY om = - CSA

Average o f values from the Dai ly Data Sheet.

Average o f values from the Dai ly Data Sheet.

Average of values from the Dai ly Data Sheet.

223

PARAMETERS USED TO MONITOR THE A B F TREATMENT PROCESS (cont inued)

colm Svmbol Svrnbol Meaning Explanation

37 RSP Return Sludge Percentage Indicat ion o f return flow percentage t h a t i s based on a sol ids balance.

ATC x 100 RSP =

RSC - ATC

38 OUR Oxygen Uptake Rate

39 WASTE Waste Volume

40 RECIRC Recirculat ion Power c- .

41 AERATION Aeration Blower Power

42 WASTE Waste Power

Average o f values from the Dai ly Data Sheet.

Average o f values from the Dai ly Data Sheet.

Average o f values from the Dai ly Data Sheet.

Average o f values from the Dai ly Data Sheet.

Average o f values from the Dai ly Data Sheet.

224

Appendix L

Suspended Growth Major Unit Process Evaluation Worksheet

This worksheet is used to evaluate the capacity of existing major unit processes, i.e., aerator, secondary clarifier, and sludge handling system. Key loading and process parameters are compared with standard values and point scores are assigned. These points are subsequently compared with expected point scores for Type 1, Type 2, and Type 3 facilities and a determination of the plant Type is made.

Instructions for Use:

0 Proceed through the steps contained in this worksheet in order.

0 Use actual values in lieu of calculations if such data are collected and available, e.9.. waste sludge volume.

0 When assigning points, interpolate and use the nearest whole number.

0 Minimum and maximum point values are indicated-do not exceed the range illustrated. c- .

Aeration Basin

Calculate Hydraulic Detention Time (HDT):

HDT = Aeration Basin Volume Average Daily Wastewater Flow

= ( cu ft) x (180) = hr ( g P 4

Determine HD T Point Score:

HDT (hr)

3 5 24 '? 15 20 ,

-6 0 Points

6 10

0 HDT Point Score =

Calculate Organic 1 oading:

BODs Loading Aeration Basin Volume

Organic Loading =

225 Suspended Growth

c. . .

Organic Loading = ( Ib'd) x (1,000) ( cu f t )

- - Ib BOD5/d/l,OOO cu ft

Determine Organic Loading Point Score:

80

Organic Loading (Ib BODs/d/l,OOO cu ft)

50 25 15

-6

Organic Loading Point Score = 0 Calculate Oxygen A vailabilit y

0 Points

6 10

If data are not available on oxygen transfer capacity, calculate it as Wire Horsepower (Appendix E) times actual Oxygen Transfer Rate (Appendix F).

( hp) x ( Ib/hp-hr) x (24) = Ib/d

Oxygen Transfer Capacity BOD5

Oxygen Availability =

Determine Oxygen Availability Point Score:

-1 0 - 0 Points

5 10

Oxygen Availability Point Score = 0 Add Scores I , 2. and 3 to Obtain Subtotal for Aeration Basin:

@ Aeration Basin Subtotal =

Suspended Growth 226

Secondary Clarifier

Determine Clarifier Configuration Point Score:

Configuration Points

Circular with "donut" or interior launders Circular with weirs on walls Rectangular with 33% covered with launders Rectangular with 20% covered with launders Rectangular with launder at or near end

10 7

-5 -5

-10

0 Clarifier Configuration Point Score =

Calculate Clarifier Surface Overflow Rate (SOR):

SOR = Clarifier Effluent Flow Clarifier Surface Area

r. . Determine SOR Point Score:

Surface Overflow Rate (gpd/sq ft)

1,200 1,000 800 650 500 300

L I I I 1 I I 1 I I 1 1 ' ' I I 1 1 1 1 ' 1 1 1 1 1 1 ' ' I I ' ' 1 I ' I 1

-1 5 - 10 0 5 Points

10 15

@ SOR Point Score =

Determine Depth at Weirs Point Score:

7

Depth at Weirs (ft)

8 10 12 15

-1 0 - 0 4

Points

10

0 Depth a t Weirs Point Score =

227 Suspended Growth

c-

Determine Return Activated Sludge (RAS) Removal Point Score:

RAS Removal Points

Circular, rapid withdrawal Circular, scraper to hoper Rectangular, co-current scraper Rectangular, counter-current scraper No mechanical removal

10 8 2 0

-5

@ RAS Removal Score =

Determine Typical RAS Rate from Following:

Process Type Return Activated Sludge Rate Minimum Maximum

%;f average daily wastewater f low

Convent; ona I (plug flow or complete mix) 25

Extended Aeration (including oxidation ditches) 50

Contact Stabilization 50

75

100 125

Minimum Typical RAS Rate = percent

Maximum Typical RAS Rate = -percent

Calculate Recommended RAS Flow Range:

Min. Typical Typical RAS Rate x POTW Flow = Min. Recommended RAS Flow

( %) x ( gpd) x (0.01) = gpd

Max. Typical Typical RAS Rate x POTW Flow = Min. Recommended RAS Flow

CJPd %) x ( gpd) x (0.01) = (

Determine Actual RAS Flow Range:

Minimum Actual RAS Flow = gpd

Maximum Actual RAS Flow = gpd

SusDended Growth 228

Determine RAS Control Point Score:

RAS Control Points

The actual RAS f low range is completely within the iecommended

The actual RAS f low range is completely within the recommended

50% of the recommended RAS flow range is covered by the actual

50% of the recommended RAS flow range is covered by the actual exist

The actual RAS f low range is completely outside the recommended

RAS flow range and the capability to measure RAS flow exists 10

RAS f low range but the capability to measure RAS flow does not exist 7

RAS flow range and the capability to measure RAS flow exists 5

RAS flow range but the capability to measure RAS flow does not 0

RAS flow range -5

@ RAS Control Point Score =

Add Scores 5, 6, 7 .8, and 9 to Obtain Subtotal for Secondary Clarifier:

r. . Secondary Clarifier Subtotal = -

Sludge Handling Capability

Determine Sludge Controllability Point Score:

Controllability Points

Automated sampling and volume control Metered volume and hand sampling Hand measured volume and hand sampling Sampling or volume measurement by hand not practical

5 3 2 0

0 Sludge Controllability Point Score =

Calculate BOD5 Mass Removed:

P O W w/Primary Clarification:

Prim. BODsin - Prim. BODsout = Prim. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

Prim. BODsout - P O W Eff. BOD5 = Sec. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

229 Suspended Growth

Prim. BOD5 Conc. Removed x POTW Flow = Prim. BOD5 Mass Removed

( mg/l) x ( gpd) x (8.34 x lo-') = Ib/d

See. BOD5 Conc. Removed x POTW Flow = Sec. BOD5 Mass Removed

POTW w/o Primary Clarification:

BODsln - P O W Eff. BOD5 = Total BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

Total BOD5 Conc. Removed x P O W Flow = Total BOD5 Mass Removed

( mg/l) x ( gpd) x (8.34 x 1 0-') = Ib/d

Determine Typical Unit Sludge Production from Following:

Ib TSS (sludge)/lb Process Type BOD5 Removed

Primary Clarification 1.7

Activated Sludge w/Primary Clarification 0.7

Activated Sludge w/o Primary Clarification Convent i ona I a 0.85 Extended Aerationb 0.65 Contact Stabilization 1 .o

~

'Includes tapered aeration, step feed, plug flow, andcomplete mix with wastewater detention times

blncludes oxidation ditch <10 hours

If plant records include actual sludge production data, the actual unit sludge production value should be compared to the typical value. If a discrepancy of more than 15 percent exists between the two values, further evaluation is needed. If not, use the actual unit sludge production value.

Calculate Expected Sludge Mass:

POTW w/Primary Clarification:

Unit Sludge Prod. x Prim. BOD5 Mass Removed = Prim Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Suspended Growth 2 30

Unit Sludge Prod. x Sec. BOD5 Mass Removed = Sec. Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Total Sludge Mass = Ib/d

P O W w/o Primary Clarification:

Unit Sludge Mass x Total BODs Mass Removed = Total Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Determine Sludge Concentration from Following:

Sludge Type Waste C o n c e n t r a t i o n mg/l

Primary 50,000

Activated Return Sludge/Conventional 6,000 Return Sludge/Extended Aeration 7,500 Return Sludge/Contact Stabilization 8,000

10,000 12,000

Return Sludge/small plant with low SOR" Separate waste hopper in secondary clarifier

"Returnscan often be shut off for short periodstothlcken waste sludge in clarlflers wlth surface overflow rates less than 500 gpd/sq ft.

Calculate Expected Sludge Volume:

P O W w/Primary Clarification:

Sludge Volume =

- -

SludgeVolume =

- -

Prim. Sludge Mass Prim. Sludge Conc.

See. Sludge Mass Sec. Sludge Conc.

Total Sludge Volume = gpd

231 Suspended Growth

P O W w/o Primary Clarification:

Total Sludge Mass Total Sludge Conc.

Total SludgeVolume =

Calculate Capacity of Sludge Handling Unit Processes:

1. Establish capacity of each existing sludge handling process (treatment and disposal). The most common unit processes for which this calculation will have to be performed are:

0 Aerobic digestion 0 Anaerobic digestion 0 Gravity thickening 0 Mechanical dewatering 0 Drying beds 0 Liquid haul

For example, the capacity of a gravity thickener is the maximum sludge loading it can handle:

Total Sludge Mass Thickener Surface Area

Thickener Loading =

2. Determine percentage of the expected sludge production that each process can handle.

Typical Process Loading Actual Process Loading

Process Capacity =

Assume the sludge being thickened by the gravity thickener above is mixed primary and activated. From Table 3-9, 10 Ib/d/sq ft is considered typical loading for the thickener. Its capacity would therefore be calculated as:

( 10 ’b/d’sq ft) x (100) = percent I , Ib/d/sq ft)

Suspended Growth 232

r- .

fist Each Process and Its Associated Sludge Handling Capacity and Identify the Lowest Percentage Capacity:

Process Percentage

Lowest Capacity = percent

Determine Sludge Handling Capacity Point Score:

% of Calculated Long-Term Average Sludge Production

5 0 75 1 00 125 150

I 1 I I I 1 I 1 - i o 0 15 20 25

Points

0 Sludge Handling Capacity Point Score =

Add Scores 1 1 and 12 to Obtain Subtotal for Sludge Handling Capability:

0 Sludge Handling Capability Subtotal =

233 Suspended Growth

Compare Subtotals and Total Score with Following to Determine Whether POTWis Type 1 , Type 2, or Type 3:

Points Required Score Type 1 Type 2 Type 3

Aeration Basin (4) 13-30 0-1 2 <O

Secondary Clarifier (10) 25-55 0-24 <O

Sludge Handling Capability (13) 10-30 0- 9 <O

Total 60-1 15 20-59 <20

Type

Aeration Basin

Secondary Clarifier

Sludgq Handling Capability

c. . . Total

Select the Worst Case: P O W is Type

Suspended Growth 2 34

Appendix M

Trickling Filter Major Unit Process Evaluation Worksheet

This worksheet is used to evaluate the capacity of existing major unit processes, i.e., aerator, secondary clarifier, and sludge handling system. Key loading and process parameters are compared with standard values and point scores are assigned. These points are subsequently compared with expected point scores for Type 1, Type 2, and Type 3 facilities and a determination of the plant Type is made.

Instructions for Use:

a Proceed through the steps contained in this worksheet in order.

0 Use actual values in lieu of calculations if such data are collected and available, e.g., waste sludge volume.

a When assigning points, interpolate and use the nearest whole number.

0 Minimum and maximum point values are indicated-do not exceed the range illustrated.

"Aerator" Calculate Equivalent Filter Media Volume:

C. . Equivalent Filter - - Actual Filter Media Specific Surface Area Media Volume Rock Filter Media Specific Surface Area

Actual Media Volume

cu ft) = c u ft - ( sq ft/cu ft) ( 43 sq ft/cu ft) (

Calculate Organic Loading:

Primary Effluent BOD5 Equivalent Filter Media Volume Organic Loading =

- . ( Ibld) x (1,000) ( cu ft)

- - Ib BOD5/d/l,OOO cu ft

Determine Organic 1 oading Point Score:

70

Organic Loading (Ib BODs/d/l;OOO cu ft)

50 30 20 10

1 I I I I I I l l l l l l l l l l

r l ' i l l l l l I l l l l l l l l l l l l I I I I I I

-20 -1 0 0 15 Freezing Temperatures

20

I I I I l l I I rT I I I r I I I I1 l r l ' l " ' I ' 1 -1 0 -5 10 20

Covered Filter/Nonfreezing Temperatures Points

Organic Loading Point Score =

235 Trickling Filter

Calcdate Recirculation Ratio:

Return Flow Recirculation Ratio = Average Daily Wastewater Flow

Determine Recirculation Ratio Point Score:

None Recirculation

1 :1 2: 1

I I I I 1 I I 1 0 2

Points

3

0 Recirculation Ratio Point Score =

Determine Anaerobic Side Streams Point Score:

Anaerobic Side Streams* Points

Not returned ahead of trickling filter

of the trickling filter

0

-1 0 Returned to the wastewater stream ahead

'Supernatant from anaerobic digesters or filtrate/concentratefrom the dewatering processes following anaerobic digesters.

0 Anaerobic Side Streams Point Score =

Add Scores 1,2. and 3 to Obtain Subtotal for 'Aerator":

c9 "Aerator" Subtotal =

Secondary Clarifier

Determine. Clarifier Configuration Point Score:

Configuration Points Circular with "donut" or interior launders 10 Circular with weirs on walls 7 Rectangular with 33% covered with launders 0 Rectangular with 20% covered with launders -5 Rectangular with launder at or near end -1 0

Trickling Filter

@ Clarifier Configuration Point Score =

2 36

Calculate Clarifier Surface Overflow Rate (SOR):

Clarifier Effluent Flow Clarifier Surface Area

SOR =

Determine SOR Point Score:

Surface Overflow Rate (gpd/sq fti

1,200 1,000 800 650 500 300 I 1 I 1 I 1 I I I I J 1 I ' I ' l l l l r l l l ' l l I I I I 1 I I ' 1

- 1 5 -10 0 5

Points 10 15

c- .

@ SOR Point Score =

Determine Depth at Weirs Point Score:

7

Depth at Weirs (ft)

10 12

I I I I I J I 1 1 1 I I

0 3

Points 5

0 Depth at Weirs Score =

Add Scores 5, 6. and 7 to Obtain Subtotal for Secondary Clarifier:

G9 Secondary Clarifier Subtotal =

237 Trickling Filter

Sludge Handling Capability

Determine Sludge Controllability Point Score:

Controllability Points

5 3 2 0

Automated sampling and volume control Metered volume and hand sampling Hand measured volume and hand sampling Sampling or volume measurement by hand not practical

Sludge Controllability Point Score = @ Calculate BODS Mass Removed:

Prim. BOD5in - Prim. BODsout = Prim. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

Prim. f%)D5o,l- POTW Eff. BODs = Sec. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

Prim. BOD5 Conc. Removed x POTW Flow = Prim. BOD5 Mass Removed

gpd) x (8.34 x = Ib/d ( mg/l) x (

See. BOD5 Conc. Removed x POTW Flow = Sec. BOD5 Mass Removed

( mg/l) x ( gpd) x (8.34 x lo-') = Ib/d

Determine Typical Unit Sludge Production from Following:

Ib TSS (sludge)/lb Process Type BOD5 Removed

Primary Clarification 1.7

Trickling Filter 1 .o

If plant records include actual sludge production data, the actual unit sludge production value should be compared to the typical value. If a discrepancy of more than 15 percent exists between the two values, further evaluation is needed. If not, use the actual unit sludge production value.

Trickling Filter 2 38

Calculate Expected Sludge Mass:

-. . .

Unit Sludge Prod. x Prim. BOD5 Mass Removed = Prim Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Unit Sludge Prod. x Sec. BODs Mass Removed = Sec. Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Total Sludge Mass = Ib/d

Calculate Expected Sludge Volume:

Method 1

Prim. Sludge Mass Prim. Sludge Conc. SludgeVolume =

Ib’d) x (120.000) = gpd - ( ( 50,000 mg/l)

See. Sludge Mass Sec. Sludge Conc.

SludgeVolume =

Ib ld) x (1 20,000) = gpd

Total Sludge Volume = gpd

- ( ( 30,000 mg/l)

Method 2

Total Slud e Mass Total Sludge Volume = Total SludgSe Cone,

Ibld) x (1 20,000) = gpd = ( ( 45,000 mgA)

239 Trickling Fi Iter

Calculate Capacity of Sludge Handling Unit Processes:

1 . Establish capacity of each existing sludge handling process (treatment and disposal). The most common unit processes for which this calculation will have to be performed are:

0 Aerobic digestion 0 Anaerobic digestion 0 Gravity thickening 0 Mechanical dewatering 0 Drying beds 0 Liquid haul

For example, the capacityof a gravitythickener is the maximum sludge loading it can handle:

Total Sludge Mass Thickener Surface Area Thickener Loading =

2. Determine percentage of the expected sludge production that each process can handle.

Typical Process Loading Actual Process Loading Process Capacity =

Assume the sludge being thickened by the gravity thickener above is trickling filter. From Table 3-9, 8 Ib/d/sq ft is considered typical loading for the thickener. Its capacity would therefore be calculated as:

( 8 Ib/d/sq “1 x (100) = -percent Ib/d/sq ft) (

list Each Process and Its Associated Sludge Handling Capacity and Identify the Lowest Percentage Capacity:

Process Percentage

Trickling Filter

Lowest Capacity = percent

2 40

Determine Sludge Handling Capacity Point Score:

c- .

% of Calculated Long-Term Average Sludge Production

5 0 75 100 125

-10 5 15 20

Points

Sludge Handling Capacity Point Score =

Add Scores 9 and 10 to Obtain Subtotal for Sludge Handling Capability:

Sludge Handling Capability Subtotal = 01 Compare Subtotals and Total Score with Following to Determine Whether POTWis Type I , Type 2, or Type 3:

"Aerator"

Secondary Clarifier

Sludge Handling Capability

Total

"Aerator"

Secondary Clarifier

Sludge Handling Capability

Points Required Score Type 1 Type 2 Type 3

(4) 17-23 0-1 1 <O

(8) 17-30 0-1 6 <O

( 1 1 ) 10-30 0- 9 <O

45-83 15-44 <15

Total

Select the Worst Case: P O W is Type

241 Trickling Filter

Appendix N

RBC Major Unit Evaluation Worksheet

This worksheet is used to evaluate the capacit! of existing major unit processes, ;.e., aerator, secondary clarifier, and sludge handling system. Key loading and process parameters are compared with standard values and point scores are assigned. These points are subsequently compared with expected point scores for Type 1, Type 2, and Type 3 facilities and a determination of the plant Type is made.

Instructions for Use:

0 Proceed through the steps contained in this worksheet in order.

0 Use actual values in lieu of calculations if such data are collected and available, e.g., waste sludge volume

0 When assigning points, interpolate and use the nearest whole number.

0 Minimum and maximum point values'are indicated-do not exceed the range illustrated c. . .

"Aerator" Calculate First-Stage Loading:

First-Stage Soluble BOD5 Loading First-Stage Media Surface Area Organic Loading =

or

(0.5) x (First-Stage BOD5 Loading) First-Stage Media Surface Area Organic Loading =

- ( Ibld) x (1,000) = Ib SBOD/d/l,OOO sq ft ( sq ft)

Determine First-Stage Loading Point Score:

6.0 First-Stage Loading (Ib SBOD/d/1,000 sq ft)

4.0 2.5

-6 0 Points

10

0 First-Stage Loading Point Score =

RBC 242

Calculate System Loading:

I I I I

C. .

I I I I I 1 1 I I

Total Soluble BOD5 Loading Total Media Surface Area

Organic Loading =

or

(0.5) x (Total BOD5 Loading) First-Stage Media Surface Area

Organic Loading =

x (1,000) = Ib SBOD/d/l,OOO sq ft - ( Ib/d)

( sq ft)

Determine System Loading Point Score:

1.5 System Loading (Ib SBOD/d/l,OOO sq ft)

1 .o 0.6

-6 0 Points

10

0 System Loading Point Score =

Determine Number of Stages Point Score:

2 No. Stages

3 4

4 7 Points

10

0 Number of Stages Point Score =

243 RBC

Determine Anaerobic Side Streams Point Score:

Secondary Clarifier c- .

Anaerobic Side Streams* Points

Not returned ahead of RBC 0 Returned to the wastewater stream ahead of the RBC -1 0 *Supernatant from anaerobic digesters or filtrate/concentrate from the dewatering

processes following anaerobic digesters.

Anaerobic Side Streams Point Score = @ Add Scores I , 2, 3, and 4 to Obtain Subtotal for "Aerator":

0 "Aerator" Subtotal =

Determine Clarifier Configuration Point Score:

Configuration Points

Circular with "donut" or interior launders 10 Circular with weirs on walls 7 Rectangular with 33% covered with launders 0 Rectangular with 20% covered with launders -5 Rectangular with launder at or near end -10

Clarifier Configuration Point Score = G9 Calculate Clarifier Surface Overflow Rate (SOR):

Clarifier Effluent Flow 'OR = Clarifier Surface Area

Determine SOR Point Score:

Surface Overflow Rate (gpd/sq ft) 1.200 1,000 800 650 500 300

-1 5 -1 0 0 5 10 15

Points

RBC

0 SOR Point Score =

2 44

Determine Depth at Weirs Point Score:

c- .

7 Depth a t Weirs (ft)

10 12

1 I I 1 I 1 I I 1 I I I

0 3 Points

5

@ Depth at Weirs Score =

Add Scores 5, 6. and 7 to Obtain Subtotal for Secondary Clarifier:

69 Secondary Clarifier Subtotal =

Sludge Handling Capability

Determine Sluc;e Controllability Point Score:

Controllability Points

Automated sampling and volume control Metered volume and hand sampling Hand measured volume and hand sampling Sampling or volume measurement by hand not practical

5 3 2 0

63 Sludge Controllability Point Score =

Calculate BOD5 Mass Removed:

Prim. BODS,, - Prim. BOD5out = Prim. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

Prim. BODsout - P O W Eff. BOD5 = Sec. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

245 RBC

Prim. BOD5 Conc. Removed x POTW Flow = Prim. BOD5 Mass Removed

( mg/U x ( gpd) x ( 8 . 3 4 ~ = Ib/d

See. BOD5 Conc. Removed x POTW Flow = Sec. BOD5 Mass Removed

( mg/l) x ( gpd) x (8.34 x lo-') = Ib/d

Determine Typical Unit Sludge Production from Following:

Ib TSS (sludge)/lb Process Type BOD5 Removed

Primary Clarification 1.7

Trickling Filter 1 .o -. . .

If plant records include actual sludge production data, the actual unit sludge production value should be compared to the typical value. If a discrepancy of more than 15 percent exists between the two values, further evaluation is needed. If not, use the actual unit sludge production value.

Calculate Expected Sludge Mass:

Unit Sludge Prod. x Prim. BODs Mass Removed = Prim Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Unit Sludge Prod. x Sec. BOD5 Mass Removed = Sec. Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Total Sludge Mass = Ib/d

Calculate Expected Sludge Volume:

Method 1

Prim. Sludge Mass Prim. Sludge Conc.

SludgeVolume = -

RBC 2 46

c- .

Sec. Sludge Mass Sec. Sludge Conc. SludgeVolume =

Total Sludge Volume = gpd

Method 2

Total Sludge Mass Total Sludge Conc. Total SludgeVolume =

IbId) x (1 20,000) = gPd = ( ( 45,000 mg/l)

Calculate Capacity of Sludge Handling Unit Processes:

1. Establish capacity of each existing sludge handling process (treatment and disposal). The most common unit processes for which this calculation will have to be performed are:

0 Aerobic digestion 0 Anaerobic digestion 0 Gravity thickening 0 Mechanical dewatering 0 Drying beds 0 Liquid haul

For example, the capacityof a gravity thickener is the maximum sludge loading it can handle:

Total Sludge Mass Thickener Surface Area

Thickener Loading =

2. Determine psrcentage of the expected sludge production that each process can handle.

Typical Process Loading Actual Process Loading Process Capacity =

Assume the sludge being thickened by the gravity thickener above is mixed primary and RBC. From Table 3-9, 15 Ib/d/sq ft is considered typical loading for the thickener. Its capacity would therefore be calculated as:

Ib/d/sq ft) x (1 00) = Ib/d/sq ft)

percent ( 15 (

2 47 RBC

List Each Process and Its Associated Sludge Handling Capacity and Identify the Lowest Percentage Capacity:

Process Percentage

Lowest Capacity = percent

Determine Sludge Handling Capacity Point Score:

% of Calculated Long-Term Average Sludge Production

50 75 1 00 125

- i o 5 15 20

Points

Sludge Handling Capacity Point Score =

Add Scores 10 and 1 1 to Obtain Subtotal for Sludge Handling Capability:

RBC

0 Sludge Handling Capability Subtotal =

248

r. .

Compare Subtotals and Total Score with Following to Determine Whether POTWis Type 1 , Type 2. or Type 3:

Points Renuired Score Type 1 Type 2 Type 3

"Aerator" (5) 14-30 0-1 3 <O

Secondary Clarifier (9) 17-30 0-1 6 <O

SI udge Handling Capability (12) 10-30 0- 9 <O

Total 48-90 15-47 <15

Type

"Aerator"

Secondary Clarifier

SI udge Ma ndli ng Capa bi I ity

Total

Select the Worst Case: P O W is Type

249 RBC

Appendix 0

ABF Major Unit Evaluation Worksheet

This worksheet is used to evaluate the capacity of existing major unit processes, i , aerator, seca dary clarifier, and sludge handling system. Key loading and process parameters are compared with standard values and point scores are assigned. These points are subsequently compared with expected point scores for Type 1, Type 2, and Type 3 facilities and a determination of the plant Type is made.

Instructions for Use:

0 Proceed through the steps contained in this worksheet in order.

0 Use actual values in lieu of calculations if such data are collected and available, e.g., waste sludge volume

0 When assigning points, interpolate and use the nearest whole number.

Minimum and maximum point values are indicated-do not exceed the range illustrated c. .

"Aerator" Calculate Biocell Organic 1 oading:

BOD5 Loading Biocell Media Volume

Organic Loading =

Ib/d) x (1,000) - ( ( cu ft)

- - Ib BODs/d/l,OOO cu ft

Determine Biocell Organic 1 oading Point Score:

Organic Loading (Ib BODs/d/l,OOO cu ft)

300 250 200 175 150 1 00

I 1 I 1 . 1 I I I 1 1 I I I I I 1 1 1 1 1 1

I ' ' ' I 1 I ' I I I I ' ' I I I I ' I ' 1 -1 0 -5 0 5 10 15

Points

ABF

0 Organic Loading Point Score =

2 50

Calculate Aeration Basin Detention Time:

1

Aeration Basin - Aeration Basin Volume Detention Time Average Daily Wastewater Flow

1 I

Determine Aeration Basin Detention Point Score:

I I I I

c- .

0 Aeration Basin Detention Point Score =

Calculate Oxygen A vailabilit y:

If data are not available on oxygen transfer capacity, calculate it as Wire Horsepower(Appendix E) times actual Oxygen Transfer Rate (Appendix F).

( hP) x ( Ib/hp-hr) x (24) = Ib/d

Oxygen Transfer Capacity Biocell BOD5 Loading

Oxygen Availability =

- ( Ib/d) - Ib On/lb BOD5 ( Ib/d)

Determine Oxygen Availability Point Score:

Oxygen Availability (Ib On/lb BOD5)

0.3 0.4 0.5 0.75 1 .o I I 1 I I l l I I I ' ~ ~ ' ' " ' ' I ' I I ' I I 1 I I I I I I I I

- 1 5 0 3 7 10 Points

0 Oxygen Availability Point Score =

251 ABF

Calculate Recirculation Ratio:

Return Flow Average Daily Wastewater Flow

Recirculation Ratio =

Determine Recirculation Ratio Point Score:

None Recirculation

0.5:l 1 :1

r I 1 1 I 0

1 2 I 3

Points

@ Recirculation Ratio Point Score =

Add Scores 1. 2, 3, and 4 to Obtain Subtotal for “‘Aerator”:

0 “Aerator” Subtotal =

Secondary Clarifier

Determine Clarifier Configuration Point Score:

Configuration Points

Circular with “donut” or interior launders 10 Circular with weirs on walls 7 Rectangular with 33% covered with launders 0 Rectangular with 20% covered with launders -5 Rectangular with launder at or near end -1 0

@ Clarifier Configuration Point Score =

Calculate Clarifier Surface Overflow Rate (SOU):

Clarifier Eff I uent Flow ’OR = Clarifier Surface Area

ABF 2 52

Determine SOR Point Score:

Surface Overflow Rate (gpd/sq ft)

1,200 1,000 800 650 500 300

L I I I I I I I 1 1 1 t ' I 1 1 1 1 1 ' 1 ' 1 1 1 I I I I 1 ' ' ' 1 I I 1

-1 5 - i o 0 5

Points

10 15

0 SOR Point Score =

Determine Depth at Weirs Point Score:

7 Depth at Weirs (ft)

10 12

I I I I 1 1 r I I 1 I I

0 3 Points

5

@ Depth at Weirs Score =

Calculate Recommended RAS Flow Range:

Min. Typical Typical RAS Rate x POTW Flow = Min. Recommended RAS Flow

( 25 %) x ( gpd) x (0.01) = gPd

Max. Typical Typical RAS Rate x POTW Flow = Min. Recommended RAS Flow

( 75 %) x ( gpd) x (0.01) = gPd

Determine Actual RAS Flow Range:

Minimum Actual RAS Flow = gpd

gpd Maximum Actual RAS Flow =

2 53 ABF

Determine RAS Control Point Score:

RAS Control Points

The actual RAS flow range is completely within the recommended RAS flow range and the capability to measure RAS flow exists

RAS f low range but the capability to measure RAS f low does not exist

RAS flow range and the capability to measure RAS flow exists

RAS flow range but the capabilityto measure RASflowdoes not

RAS f low range -5

_ r

10

7

5

0

The actual RAS f low range is completely within the recommended

50% of the recommended RAS flow range is covered by the actual

50% of the recommended RAS f low range is covered by the actual exist

The actual RAS f low range is completely outside the recommended

@ RAS Control Point Score = --

Add Scores 5, 6, 7 ,8 , and 9 to Obtain Subtotal for Secondary Clarifier:

63 Secondary Clarifier Subtotal =

Slud e Handling Capagility

Determine Sludge Controllability Point Score:

Controllability Points

Automated sampling and volume control Metered volume and hand sampling Hand measured volume and hand sampling Sampling or volume measurement by hand not practical

5 3 2 0

0 Sludge Controllability Point Score =

Calculate BOD5 Mass Removed:

Prim. BODsln - Prim. BOD~,,l = Prim. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

Prim. BODeout - POTW Eff. BOD5 = Sec. BOD5 Conc. Removed

( mg/l) - ( mg/l) = mg/l

ABF 2 54

Prim. BOD5 Conc. Removed x POTW Flow = Prim. BOD5 Mass Removed

( mg/l) x ( gpd) x (8.34 x = Ib/d

See. BOD5 Conc. Removed x POTW Flow = Sec. BOD5 Mass Removed

( mg/l) x ( gpd) x (8.34 x = Ib/d

Determine Typical Unit Sludge Production from Following:

Ib TSS (sludge)/lb Process Type BOD5 Removed

Primary Clarification 1.7

Trickling Filter 1 .o

If plant records include actual sludge production data, the actual unit sludge production value should be compared to the typical value. If a discrepancy of more than 15 percent exists between the two values, further evaluation is needed. If not, use the actual unit sludge production value.

Calculate Expected Sludge Mass:

Unit Sludge Prod. x Prim. BODs Mass Removed = Prim Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Unit Sludge Prod. x Sec. BOD5 Mass Removed = Sec. Sludge Mass

( Ib/lb) x ( Ib/d) = Ib/d

Total Sludge Mass = Ib/d

Calculate Expected Sludge Volume:

Method 1

Prim. Sludge Mass Prim. Sludge Conc. SludgeVolume =

255 ABF

Sec. Sludge Mass Sec. Sludge Conc. SludgeVolume =

Total Sludge Volume = 9 Pd

Method 2

Total Sludge Mass Total Sludge Conc.

Total Sludge Volume =

IbId) x (120,000) = 9 Pd = ( ( 35,000 mgI l )

Calculate Capacity of Sludge Handling Unit Processes:

1 , Establish capacity of each existing sludge handling process (treatment and disposal). The most common unit processes for which this calculation will have to be performed are:

0 Aerobic digestion 0 Anaerobic digestion 0 Gravity thickening 0 Mechanical dewatering 0 Drying beds 0 Liquid haul

For example, the capacityof a gravitythickener is the maximum sludge loading it can handle:

Total Sludge Mass Thickener Surface Area

Thickener Loading =

2. Determine percentage of the expected sludge production that each process can handle.

Typical Process Loading Actual Process Loading

Process Capacity =

Assume the sludge being thickened by the gravity thickener above is ABF. From Table 3-9,4 Ib/d/sq ft is considered typical loading for the thickener. Its capacity would therefore be calculated as:

ABF 256

_*. . . ..

List Each Process and Its Associated Sludge Handling Capacity and Identify the Lowest Percentage Capacity:

Process Percentage

Lowest Capacity = percent

Determine Sludge Handling Capacity Point Score:

% of Calculated Long-Term Average Sludge Production

50 75 1 00 125

I 1 1 1 t I 1 I 1 I 1

- i o 5 15 20

Points

Sludge Handling Capacity Point Score =

Add Scores 1 1 and 12 to Obtain Subtotal for Sludge Handling Capability:

Sludge Handling Capability Subtotal = 0

257 ABF

a

Compare Subtotals and TotalScore with Following to Determine Whether POTWis Type I , Type 2, or Type 3:

Points Reouired Score Type 1 Type 2 Type 3

"Aerator" (5) 15-48 0-14 <O

Secondary Clarifier (10) 20-55 0-1 9 <O

Sludge Handling Capability (13) 10-30 0- 9 <O

Total 50- 1 33 15-49 <15

Type

"Aerator"

Secondary Clarifier

Sludge Handling Capability

Total

Select the Worst Case: POTW is Type

ABF

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