Lean Six Sigma

Increasing Waste Activated SludgeCheryl Cronin, Waste Water Treatment Plant

Project Description

Objective: Increase gallons of W.A.S. processed by 40% and increase Total Solids to 4 to 5%

Problem Problem Statement:Statement:

• Only 50% of W.A.S is processed through the Centrifuge currently at an average Total Solids of 2.2%.

• Gallons wasted in 1999 – 176.15 MG• Gallons Processed at Centrifuge – 88.1 MG• Average TS (Thickened) – 2.2%• Average TS (W.A.S) – 0.7%

Benefits

•Savings of $28,000 per year (fuel and treatment)

•$1.7 M for additional digester space

•Plant able to treat 88,000,000 more gallons per year – Reduction in CSO’s

Champion: Ted Rhinehart

Financial: Ned Byrer

Black Belt: Cheryl Cronin

Mechanic: Brian Panzer

Process Analyst: Gwen Bard

Laboratory: John Kohne

Operator: Mike Glymph

Operator: Jeff Vachon

Technical: Chris Gach

Project Team

• Measurement: 07/17/00

• Analyze: 08/25/00

• Improvement: 09/29/00

• Control: 11/03/00

• Completion 12/30/00

Schedule

• Digester Space – Less Water, less energy for heating.• 33% reduction in use = $10,000.00

• Additional Digesters• “Class A” sludge must have a 38% reduction in Volatile

Solids and 15 day Detention time. • Currently there is an average 45% reduction and 7 day

detention. By EPA standards, another digester is needed to achieve a 15 day detention at a cost of $1.7M.

• Reduction of Million Gallons Treated • $18,000 in savings

• Increased Capacity of Primaries Tanks

Savings

“Y”

Million gallons of W.A.S. processed through Centrifuge at 4% TS or higher per week

Y =

Clarifiers with Sludge

WAS Wet Well

CentrifugeThickened Sludge Pumping

Thickened Sludge Pumping

50,000 Foot Process Map

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Process Step Process Inputs Waste

Tim

e

Wasting R

ate

Thic

k S

ludge

Thin

Slu

dge

Centr

ate

Ideal S

ludge

Plu

gged

Lin

e

Total

1 Clarifier Blanket Level 9 9 0 0 1 1 1 1172 Clarifier MLSS 9 9 0 0 1 1 1 1173 Clarifier SSV 9 9 0 0 1 1 1 117

Clarifier Operator Time 9 1 0 0 1 1 1 85

4 Wet WellWet Well Height

9 9 0 0 1 1 1 117

Wet Well Operator Time 9 1 0 0 1 1 1 855 Centrifuge Pinion Speed 1 1 0 0 5 9 1 1056 Centrifuge Load 1 1 0 0 1 9 1 1017 Centrifuge Feed Rate 5 5 0 0 1 5 1 109

Centrifuge Operator Time 1 1 0 0 1 9 1 101

8 CentrifugeTSS incoming sludge

1 1 0 0 1 5 1 65

9 Thickened PumpThick Sludge 1 1 0 0 1 1 9 9310Thickened PumpPSI 1 1 0 0 1 1 9 93

Thickened PumpOperator Time 1 1 0 0 1 1 9 93Thickened PumpON 1 1 0 0 1 9 9 165Thickened PumpOFF 1 1 0 0 1 1 1 29

11Thickened PumpWet Well Height

1 1 0 0 1 1 1 29

12 Overall Operator Time 5 1 0 0 1 9 5 161

13 OverallSeason Weather

5 1 0 0 1 1 1 57

14 015 016 017 018 019 020 0

0

Total 399

196

0 0 17

405

0 0 264

0 0 0 0 0 0

C & E Matrix

0Subgroup 10 20 30

4

5

6

7

8

Indi

vid

ual V

alue

66 6 2

1

1

6

Mean=5.83

UCL=7.426

LCL=4.234

0

1

2

Mov

ing

Ran

ge

R=0.6

UCL=1.960

LCL=0

Thickened Sludge Solids for September 2000

% Solids in September

• After completing process mapping and the C & E matrix we were able to improve the process by moving the average thickness of the sludge to 5.2% and have kept the centrifuge running for 3months non-stop.

• My new objective is to increase the gallons of WAS sludge processed by 40% and increase the thickness of the sludge to 6 to 8%.

Revised Objective

0 50 100

0

5

10

15Individual and MR Chart

Obser.

Indi

vidu

al V

alue

Mean=4.23

UCL=8.265

LCL=0.1953

0.0

2.5

5.0

7.5

Mov

.Ran

ge

R=1.517

UCL=4.957

LCL=0

105 115 125

Last 25 Observations

1.0

2.5

4.0

5.5

Observation Number

Val

ues

4 8Ppk: 0.02Pp: 0.41Scale: 4.76037Shape: 2.52216

Overall (LT)

Capability PlotProcess Tolerance

Specifications

I I I

I I I

1 10

Weibull Prob Plot

0 5 10

Capability Histogram

Thickened Sludge Solids

14121086420

USLLSL

Capibility Thickened Sludge

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

PPM Total

PPM > USL

PPM < LSL

Ppk

PPL

PPU

Pp

Cpm

Cpk

CPL

CPU

Cp

StDev (Overall)

StDev (Within)

Sample N

Mean

LSL

Target

USL

603087.35

155464.16

447623.19

526176.59

94071.62

432104.97

561403.51

78947.37

482456.14

0.04

0.04

0.34

0.19

*

0.06

0.06

0.44

0.25

1.74681

1.34489

114

4.23

4.00

*

6.00

Exp. "Overall" PerformanceExp. "Within" PerformanceObserved PerformanceOverall Capability

Potential (Within) Capability

Process Data

Within

Overall

Capability

• Developed a more timely method to measure the influent W.A.S

• Developed a method to measure the thickened sludge out of the centrifuge during production

• Current methods are 24 hours behind actual operation

Measurement Studies

• Rented a viscometer and did an initial study that told us that we should be able to correlate CPs with % solids.

• Did a Gage R % R to confirm

Thickened Sludge Measurement System

Gage name:Date of study:Reported by:Tolerance:Misc:

thickened sludge9-21-00Cheryl Cronin.4%

%Contribution %Study Var %Tolerance

Gage R&R Repeat Reprod Part-to-Part

0

5000000

10000000

15000000

Components of Variation

Per

cent

Gage R&R (ANOVA) for C2

Gage R & R Study on Effluent Measure System

StdDev Study Var %Study Var %ToleranceSource (SD) (5.15*SD) (%SV) (SV/Toler) Total Gage R&R 1622.6 8356.3 13.90 8.36E+05 Repeatability 1037.6 5343.4 8.89 5.34E+05 Reproducibility 1247.5 6424.5 10.68 6.42E+05 C1 75.6 389.2 0.65 38923.91 C1*trials 1245.2 6412.7 10.66 6.41E+05 Part-To-Part 11563.4 59551.5 99.03 5.96E+06

Total Variation 11676.7 60134.9 100.00 6.01E+06

Number of Distinct Categories = 10

Effluent Gage Stats

Gage name:Date of study:

Reported by:Tolerance:

Misc:

Influent10-18-00

Chery l Cronin1000 ppm

0

0.35

0.45

0.55

0.65

0.75

0.85

0.95

1.05 Bob J eff M ik e

Xbar Chart by Operator

Sam

ple

Mean

Mean=0.6983UCL=0.7512

LCL=0.6455

0

0.00

0.05

0.10

0.15 Bob J eff M ik e

R Chart by Operator

Sam

ple

Range

R=0.05167

UCL=0.1330

LCL=0

1 2 3 4 5 6 7 8 9 10

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Trial

OperatorOperator*Trial Interaction

Avera

ge

Bob

Jeff

Mike

Bob Jeff Mike

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Operator

By Operator

1 2 3 4 5 6 7 8 9 10

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Trial

By Trial

%Contribution

%Study Var

Gage R&R Repeat Reprod Part-to-Part

0

50

100

Components of Variation

Perc

ent

Influent Gage

Gage R & R Study on Influent Measure System

StdDev Study Var %Study VarSource (SD) (5.15*SD) (%SV) Total Gage R&R 0.040044 0.20623 19.76 Repeatability 0.035285 0.18172 17.42 Reproducibility 0.018934 0.09751 9.35 Operator 0.018934 0.09751 9.35 Part-To-Part 0.198604 1.02281 98.03 Total Variation 0.202601 1.04339 100.00

Number of Distinct Categories = 7

Influent Gage Stats

• Collected Data on Operators, Shift, Wet Well Height, Lab centrifuge results, Feed rate, Pinion Speed, Load, Viscometer results.

• Length of the Test 12 days

• Purpose to eliminate more “Xs”

Multi-Vari Testing

-2 0 2 4 6 8 10 12 14

LSL USL

Process Capabil ity Analysis for lab % sol

USL

Target

LSL

Mean

Sample N

StDev (Within)

StDev (Overall)

Cp

CPU

CPL

Cpk

Cpm

Pp

PPU

PPL

Ppk

PPM < LSL

PPM > USL

PPM Total

PPM < LSL

PPM > USL

PPM Total

PPM < LSL

PPM > USL

PPM Total

8.00000

*

4.00000

5.85978

138

1.34137

2.52848

0.50

0.53

0.46

0.46

*

0.26

0.28

0.25

0.25

376811.59

376811.59

753623.19

82800.25

55295.15

138095.39

231007.21

198652.47

429659.68

Process Data

Potential (Within) Capability

Overall Capability Observed Performance Exp. "Within" Performance Exp. "Overall" Performance

Within

Overall

Multi-Vari Study

• We can make either thick or thin sludge but have problems making sludge in the 6 to 7 % range.

• We see that operators still have separate methods for making sludge.

• We have developed a reliable method for determining the thickness of influent sludge.

• Load is significant to making thick sludge

Conclusions to Multi-Vari

• Wet well height is not significant

• Operators have a big impact on sludge produced

Conclusions to Multi-Vari

Centrifuge runs 44.9% of the available time

Progress Update

INITIAL CAPABILITY

POST-PROJECT CAPABILITY

Centrifuge runs 82% of available time

Our goal was to improve processing time by 40 %. To date processing time has improved 37.3%

Total Improvement

Centrifuge Run time vs Actual Hrs in months

0

100

200

300

400

500

600

700

800

July Aug. Sept. Oct. Nov. Dec.

200

Ho

urs

Actual Hrs. Ran Actual Hours in Month

Total Hours for last 6 months of 2000. = 4416

Total Centrifuge run time = 3631or 82.2% of total time.

Centrifuge Runtime

July-December 2000

2.2% Average Total Solids

Progress Update

Initial Capability

Final Capability

5.01% Average Total Solids

Initial Goal

Increase to 4-5% Average Total Solids

Sludge Thickness

02468

Month

Pe

rce

nt

Monthly Average

Goal

3.4% 4.7% 5.1% 5.8% 5.6% 5.3% 5.0%

Thickening Results

• Volatile Solids Reduction in 1999 was 44.9% and in the last 6 months of 2000 it has increased to 58.4% Goal is to be above 38%

• Detention time in the Digesters in 1999 was 7.3 days and since this project was started the average detention time has increased to 10 days in December . Goal is to be 15days or better.

Progress Update

Digester Sludge 1999 thru 2000

0

2

4

6

8

10

12

14

Jan.

Feb.

Mar

.

April

May

June

July

Aug.

Sept

.

Oct.

Nov

.

Dec

.

Jan.

Feb.

Mar

.

April

May

June

July

Aug.

Sept

.

Oct.

Nov

.

Dec

.

2 years

M.G

. Digested Sludge

Linear (Digested Sludge)

Sludge Flow to Digester 1999-2000

• In 1999 $8,200 was spent on diesel fuel.

• In 2000 $244. was spent on diesel fuel.

Progress Update

MeasureMeasure

AnalyzeAnalyze

ImproveImprove

ControlControl

ProjectDescription

ProcessMap

C & EMatrix

PreliminaryFMEA MSA

InitialCapability Study

Multi-Vari

DOE (or other improvement)

ControlPlan

Hand OffTraining

Final Capability

Study

OwnerSign-Off

Final ProjectReport

Project TrackingProject Tracking

• Set up at DOE (February)

• Develop a control Plan (March)

Next Step

In December of 2006, all equipment and programming changes were completed. The operators no longer have to make any adjustments once the process has started. They only have to set the load needed and the PLC does the rest.

Hands-Off Training