Effective Use of Filter Pilot Testing and Chlorine Dioxide Demonstration Testing to Optimize...

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2013 NYC Watershed/Tifft Science and Technical Symposium

PA

Effective Use of Filter Pilot Testing and Chlorine Dioxide Demonstration Testing to Optimize Treatment Plant PerformanceJohn Civardi, PE – Hatch Mott MacDonaldSeptember 19, 2013

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PA Outline

· Background of Aqua Shenango Water Treatment Plant· Operational Issues and Treatability Study· UV Peroxide at Shenango· DAF Pilot Testing· Filter Testing Phases 1, 2, and 3· Chlorine Dioxide Testing, bench and demonstration· Where We Are Now

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PA Plant Background

• Capacity 16 MGD

• Raw water from the Shenango River in Sharon, PA.

• Treatment: ballasted flocculation and dual media filtration, chlorine for primary disinfection and chloramines for secondary disinfection

• Plant commissioned in early 2000.

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PA Plant Schematic

Pilot Area

Shenango River

Raw Water Pump

FiltersKMnO4 ClearwellACTIFLOChlorine Alum

Lime

Soda Ash

PAC

Chlorine

Caustic Soda

Filter Aid Polymer

Chlorine

Corrosion Inhibitor

PACAmmonia

To Distribution

Caustic SodaSoda Ash

Fluoride

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PA Plant Operational Issues

· Disinfection By-Products• Range HAAs (53.7-97.7 ppb)

• Range TTHMs (39.0-85.1 ppb)

· UFRVs< 10,000 gal/sf, – Short Filter Runs

· Algae· T&O Geosmin and MIB at 160 ng/L· Manganese

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PA Water Quality Raw & Treated (Average Conditions)

Turbidity (NTU) TOC (mg/l) Algae

(Counts/ml) Manganese (ppm)

Raw 9.6 5.67 16535 0.11

Filter Influent 0.85 3.46 880 0.03

Treated 0.08 3.12 11 ND

Shown Data collected from Pilot Study from 9/15/11 to 1/23/2012

Water Quality/Performance Issues (Maximum Conditions)Turbidity

(NTU) TOC (mg/l) Algae (Counts/ml) Manganese (ppm)

Raw 102.1 7.1 37440 0.33

Filter Influent 3.39 6.4 2480 0.08

Treated 0.16 4.1 36 0.08

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PA Treatability Study

Options Matrix

River 4 MG Pre Sed Basin

Replace Filter Media

Option 1: PAC KMnO4

UV-H2O2 Clearwell

Several variations were also considered

Option 2:

River ACTIFLO Ozone Replace Filter Media

CLO2

UV-H2O2 Clearwell

Option 3:

River ACTIFLO DAF Replace Filter Media

CLO2

UV-H2O2 Clearwell

ACTIFLO

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Historical T&O Treatment and Problems

· Powdered Activated Carbon

· Residuals Generation

· PAC provided limited removal especially with Actiflo

· Competitive effects of alum

· Could PAC be optimized and is AOP a suitable option?

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PA

Bench Testing at Aqua’s Neshaminy WTP

· Removal of up to 90% Geosmin & MIB is desired at maximum plant capacity

· Aqua and Carbon Supplier performed jar tests with Geosmin to assess :– Potential competitive effects of alum on carbon usage –

literature contained limited data

– Optimum type of PAC

– Optimum dose and detention time

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PA PAC Testing Results

· Dosing PAC together with alum results in significantly lower MIB removal (28% removal Alum/PAC vs 55% PAC then alum)

· Testing found that PAC should be added prior to alum· Minimum PAC detention time is 45 minutes· Min./Max. PAC dosage is 30 mg/L - 60 mg/L

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PA Plant Impacts of Testing

· 45 Minutes of Detention Time at 15 MGD requires at 500,000 gallon pre-carbon contact tank with mixers

· 30 mg/L dosage results in an additional 3,800 ppd of Dry Solids

· This would double the plant solids production and require additional residuals treatment equipment

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PA Cost Comparison AOP vs PAC

UV – H2O2 PACCapital $2.5 Million $2.2 Million

O&M $200,000 $310,000

Equivalent Uniform Annual Cost

$384,000 $475,000

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PAA Bit About Carbon Footprint

20 Year Total Carbon Footprint Comparing UV-oxidation and PAC

0

5000

10000

15000

20000

25000

30000

35000

PAC TrojanUVSwift™ECT

Taste and Odor Technology

Tons

of C

02 E

quiv

alen

ts

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PA Comparison with PAC

· No additional sludge handling is needed whereas the PAC process will generate approx 1.5 tons per day of dry solids (100% increase in solids production)

· Ability to provide 1 log and higher removal of MIB and Geosmin· Ability to achieve additional microbial disinfection· Smaller footprint than the PAC option· Produces less than 25% CO2 compared to UV/Peroxide

· Aqua Selected UV-Peroxide

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PA

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PA

UV Process Layout Shenango WTP

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PA

UV Process Layout Shenango WTP

Hydrogen Peroxide

UV ReactorFlow Meter

Chlorine

Cooling Water Return

Cooling Water Supply

NC

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PA

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Treatability Study to Optimize Filtration

· Technical Experts· Workshops· Selected DAF, Filters, and Chlorine Dioxide

– DAF minimizes residuals, low polymer use, algae performance

ACTIFLO

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PA

Recommended Option Schematic

Shenango River

Raw Water Pump

FiltersKMnO4 ClearwellACTIFLOChlorine Alum

Lime

Soda Ash

PAC

Chlorine

Caustic Soda

Filter Aid Polymer

Chlorine

Corrosion Inhibitor

PACAmmonia

To Distribution

Caustic SodaSoda Ash

Fluoride

Pilot: Dissolved Air Flotation Pilot: Filter

OptimizationTo

Waste

Integration of DAF into the Plant

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PA Pilot Testing

· Control/Baseline· Components· Coordination with Regulators· Vendors· Why Pilot Test?

– Proof of Design Concept

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PAPilot Testing Continued

· The Team– Owner: Aqua, PA Plant Staff and Main Office Water Quality, Engineering, and

Laboratory in Bryn Mawr, PA

– Engineer: HMM Pilot Engineer (Pittsburgh, PA), Data Review & Coordination (Millburn, NJ)

– Vendors: DAF Supplier (IDI), Filter Constructor

– PADEP – Protocol Approval

· Cost – New Filter Columns, DAF Rental, Power, Chemicals· Data Management· Communication: Weekly Conference Calls

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PA

Pilot TestingContinued

Backwash Controls

Filter Columns

Online Analyzers

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PA Protocol

· Three seasons: (1) High Algae (2) Cold Water (3) High Turbidity– Phase 1: Filter Optimization (9/27/11 - 10/13/11)

– Phase 2: DAF and Filters at Control Steady State (10/20/11 - 11/23/11)

– Phase 3: Filter Optimization for Ballast Flocculation (12/6/11 – 1/24/2012)

– Phase 4: Chlorine Dioxide Addition

· Control Column with Same Media as Existing Plant Filters · High Turbidity Modifications with Pre-Sedimentation Tank· Integrated Chlorine Dioxide & Sulfuric Acid

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PA

Pilot Testing Schematic

pH Adjustment

Raw Water

Coagulant

Flocculation Chambers

Sample Point

Polymer (if needed)

Air Compressor & Saturator

DAF Tank

Clarified Water

Sludge Scraper

Recycle Pump

To Filters

To Waste

Filter Column 60

Filter Column GAC

Filter Column 47

Filter Column 72

To Waste

From ACTIFLO

Same Configuration as Plant

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PA

Testing Matrix & Lab Coordination

Regular Analytical Schedule

Measurement

Sample Point

FrequencyField

or Lab1

1 2 3 4

Raw Water

Pilot Filter Column Effluent

Plant Clarified Water

Plant Combined Filter Effluent

Turbidity X X X X Online and manually once per day Field

Particle Counts X X X X OnlineWater

Temperature X Once per day Field

pH X X X X 1,2 Online and all manually once per day Field

True Color X X X X Once per day FieldUV254 X X X X Once per day Field

TOC/DOC X X X X Twice per week LabAlkalinity X X Once per day Field

Filterability X Once per day FieldAluminum (total and dissolved) X X X X Once per day Lab

Iron X X X X Once per day LabManganese X X X X Once per day Lab

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PA Testing Schedule

Phase 1

Phase 2

Phase 3

Phase 4

9/27/201110/17/2011

11/6/201111/26/2011

12/16/20111/5/2012

1/25/20122/14/2012

Start Date

Optimizing: pH, Acid & CLO2

Dosage, Flow Rates.

Filter Optimization with Chlorinated ACTIFLO Water

Chlorine Dioxide

Optimize Filter

DAF Running at Steady State

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PA

Phase 1: Optimize Filter using Treated ACTIFLO Water

Filter Media Configuration

Pilot Filter

Column

Sand Media

Depth (in)

Effective Size

(mm)Uniformity Coefficient Type Depth

(in)Effective

Size (mm)Uniformity Coefficient

Total Media Depth

(in)

47 12 0.45-0.55 1.4 Anthracite 35 0.85-0.95 1.4 47

60 12 0.45-0.55 1.4 Anthracite 48 1.15-1.25 1.4 60

72 12 0.65-0.75 1.5 Anthracite 60 1.45-1.55 1.4 72

GAC 12 0.45-0.55 1.4 GAC 60 1.0-1.2 1.5 72

Column 47 Represents the Configuration of the Plant’s Filter

Initial Filter Testing Results

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· Phase 1 Conclusion: Filter GAC had Lower Run Times than Existing Plant Filter Configuration.

· Filter 72 had the Longest Run Times Compared to All Columns· Replace Filter GAC with Filter 72 Configuration Under ACTIFLO

Treated Water for Benchmark Comparison to DAF· Continue to Phase 2



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PA DAF & Filter Testing


Pilot Filter Column

Sand Anthracite

Depth (in) Effective Size (mm)

Uniformity Coefficient Depth (in) Effective Size

(mm)Total Media Depth (in)

47 12 0.45-0.55 1.4 35 0.85-0.95 47

60 12 0.45-0.55 1.4 48 1.15-1.25 60

72 12 0.65-0.75 1.5 60 1.45-1.55 72

72 12 0.65-0.75 1.5 60 1.45-1.55 72

Phase 2: Dissolved Air Flotation Under Steady State ConditionsColumn 72 is the Optimal Configuration from Phase 1 using ACTIFLO Treated Water

Column 47 is the Existing Plant Configuration using DAF Treated Water


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PA DAF Testing

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PA

DAF & Filters During High Turbidity EventsPA

· Raw Water (Primary Axis) & Filter Influent (Secondary Axis)

Turbidity Spike

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PA

DAF & Filters During High Turbidity EventsPA

· Phase 2: Effluent Turbidity with DAF Treated Water

Turbidity Spike

Filter 1: 35” AnthraciteFilter 2: 48” AnthraciteFilter 3: 60” AnthraciteFilter 4: 60” Anthracite (ACTIFLO)

ACTIFLO

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PA

DAF & Filters During High Turbidity Events

Phase 2: Effluent Turbidity with DAF Treated Water

Turbidity Spike

ACTIFLO

Date

47 60 72 72

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PA Initial Conclusions

Filter

ACTIFLO Treated Water DAF Treated Water Comparison DAF/ACTIFLO

Phase (No.) Average UFRV (gals/sf) Phase (No.) Average UFRV

(gals/sf) UFRV (Ratio)

47 1 4,542 2 11,512 2.5360 1 7,211 2 15,516 2.1572 1 8,670 2 15,507 1.79

· DAF Improved Filter Runs (UFRV) · DAF Could Not Handle High Turbidity Events and the Addition of

Pre-sedimentation was not Cost Effective· Next Step – Optimize Filters for ACTIFLO

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PA Additional Filter Testing

· Phase 3: Filter Optimization with Chlorinated ACTIFLO Treated Water Under Cold Temperature Conditions – Column 47: Existing Plant’s Configuration– Column 60 & 72: Optimal Configurations from Phases 1 & 2


Pilot Filter Column

No.

Sand Anthracite

Depth (in)

Effective Size (mm)

Uniformity Coefficient

Depth (in)

Effective Size (mm)

Uniformity Coefficient

Total Media Depth

(in)

47 12 0.45-0.55 1.4 35 0.85-0.95 1.4 47

60 12 0.45-0.55 1.4 48 1.15-1.25 1.4 60

72 12 0.65-0.75 1.5 60 1.45-1.55 1.4 72


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PA Filter Data #1 Phase 3:

Turbidity Under Protocol Threshold

Date

47 60 72

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PA

Phase 3: Head-Loss with ACTIFLO Treated WaterBackwash Occurs when Head-Loss Reaches 120 Inches

Filter Data #2

Filter’s 60 & 72 Have

Longer Run Times

Compared to Filter 47 (Existing

Plant)

Date

47 60 72

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PA

Evaluation of Filter Data & Selection of Media

Table 3.1: Filter Performance Evaluation Criteria Summary*

Pilot Filter

Media Configuration

Filtered Water Turbidity

Filter Run Volume Filtered Water Color (true)

Filtered Water Manganese:

< 0.1 NTU > 7,500 gal. at < 10 ft headloss

< 5 Pt-Co color units < 0.01 mg/L

4735” Anth./12” Sand (control)

6048” Anth./12”

Sand +

7260” Anth./12”

Sand

GAC60” GAC/12”

Sand

* A “” indicates that the evaluation criteria goal was achieved. A “+” indicates that the filter media performed better than the existing plant’s filter media.

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PA


· Summary of PADEP Requirements: Effective Size, Length/Depth Ratios– Min. 12 in of Media in Effective Size Range No Greater than 0.45 to 0.55 mm

– Ratio Depth (in) to Media Effective Size (mm) Greater than 40

– Anthracite Effective Size 0.8 mm to 1.2 mm, Uniformity Coefficient No Greater than 1.7

– Sand at Least 85% Siliceous Material with an Effective Size of 0.45 to 0.55 mm and a Uniformity Coefficient No Greater than 1.65

· Cost· Availability of Media

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PA


· Selection of Filter Media: Column 60– Improved UFRV by 40%, Meaning Longer Filter Runs

– Complies with PADEP Standards

– Deeper Anthracite Layer with Larger Effective Size

– Additional 2 Inches of Sand for Pathogen Barrier

– Achieves Water Quality Similar to Existing Filters

Optimal Filter Media Configuration Selected

Pilot Filter

Column No.

Sand Media

Depth (in)

Effective Size (mm)

Uniformity Coefficient Type Depth

(in)Effective

Size (mm)Uniformity Coefficient

Total Media Depth

(in)60 12 0.45-0.55 1.4 Anthracite 48 1.15-1.25 1.4 60

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PA Chlorine Dioxide

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PABenefits of Chlorine Dioxide at the

Shenango Plant

1. Oxidation of manganese before flocculation allows the manganese to be removed during the clarification process (ACTIFLO) and allows the chlorine dosage applied to the filter influent to be reduced or eliminated.

2. Reduction of the chlorine dosage at the filter influent results in reductions in DBP formation in the Shenango distribution system.

3. Chloramination can increase biofilm and cause nitrification in the distribution system. Chlorine dioxide normally breaks down to form chlorite ion. Studies have shown that the presence of chlorite ion in finished water results in better control of organisms in the distribution system, especially those which cause nitrification

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PA Approach at Shenango

· Bench Testing· Pilot Testing with DAF· Demonstration Testing· Procurement

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PA Bench testing with ClO2

0 1 2 3 4 5 6 7 8 9 100.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

Chlorine dioxide demand/decay in Shenango raw water. Temp. = 20˚C, pH = 6.2, Mn2+ = 250 mg/L, TOC = 6.58 mg/L.

2.0 mg/L 1.5 mg/L 1.0 mg/L

Time (min)

ClO

2 (m

g/L)

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PA

0.0 0.5 1.0 1.5 2.0 2.50.00

0.05

0.10

0.15

0.20

0.25

0.30

Chlorine dioxide dose (mg/L)

Dis

solv

ed M

n R

esid

ual (

mg/

L)

10 minutes of detention

Bench Testing Chlorine Dioxide

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PA Bench Testing Ozone

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.50.00

0.05

0.10

0.15

0.20

0.25

0.30

Ozone dose (mg/L)

Dis

solv

ed M

n R

esid

ual (

mg/

L)

10 minutes of detention

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PA How is CLO2 Delivered?

· ClO2 is best supplied via On-Site Generation Systems– ClO2 gas is too energetic to package and ship - heat, light, pressure, shock

sensitive

– Road transport of ClO2 gas or solutions is not allowed

– Bulk Shipment of CDG 3000 (0.3%) contains 6 lbs chlorine dioxide· Which are then either oxidized or reduced to obtain chlorine

dioxide:– ClO3- chlorate ion

– ClO2 chlorine dioxide

– ClO2- chlorite ion

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PA Demonstration Testing

The purpose of this full scale test was to evaluate the effectiveness of chlorine dioxide as a pre-oxidant to improve the following:

1. Manganese removal in the ballasted flocculation system.

2. Reduction in filter top chlorine dose while still achieving similar pathogen inactivation. Pre-oxidation with chlorine dioxide was expected to reduce the chlorine demand and allow a reduction in the applied disinfection chlorine dose while still maintaining the same effluent chlorine residual.

3. Reduction in formation of DBPs in the combined filter effluent.

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PA Demonstration Test

· The CLO2 system delivered 15 to 150 pounds per day (ppd) of chlorine dioxide. At an average plant flowrate of 9.5 MGD and a dose of 1.0 mg/L, approximately 80 ppd of chlorine dioxide was used. At a maximum plant flowrate of 16.0 MGD and a dose of 1.0 mg/L, approximately 135 ppd of chlorine dioxide was used.

· The chlorine dioxide system was furnished by Siemens and was a Millennium III™ C-150 Auto two chemical flow-pacing chlorine gas/sodium chlorite chlorine dioxide generator capable of producing up to a maximum of 150 lbs/ day of chlorine dioxide with a 10:1 turn-down and automatic flow-pacing capability. Chlorine gas was supplied using the plant’s existing pre-chlorinator. Sodium chlorite at a strength of 25% was used and was delivered in 250 gallon totes. At the maximum chlorine dioxide usage of 150 ppd, 84 gallons of sodium chlorite was used and 79 pounds of chlorine was used.

· As this was a demonstration test treating the entire plant flow, design standards from the Pennsylvania Department of Environmental Protection’s Public Water Supply Manual 383-2125-108 Section IV.B.2 were followed.

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PA Findings

Disinfection Byproducts (µg/L) Parameter Value

Chlorine Dioxide Study 2011 Weekly Data (Aug-Nov) CFE1 Tap2 CFE1 Tap2

TTHMs Max 28.1 49.8 49.9 85.1 Mean 12.5 26.0 28.7 53.7 Min 5.6 12.2 14.8 34.5

HAAs Max 37.7 61.5 103.8 97.7 Mean 22.2 41.6 71.7 70.5 Min 9.2 29.9 47.7 53.7

1. CFE is the combined filter effluent 2. Tap is the plant effluent tap.

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PA Chlorite Levels

Distribution System Chlorite (mg/L)

Location 8/27/2012 9/12/2012 10/29/2012 11/7/2012

Chlorine Dioxide Dose 0.75 1.00 1.00 1.00

Near Entry Point 0.344 0.501 0.617 0.536

Average Residence Time 0.324 0.494 0.561 0.538

Maximum Residence Time 0.164 0.278 0.337 0.438

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PA Summary

· UV-Hydrogen Peroxide is feasible and cost effective for Geosmin and MIB reduction

· DAF provided significant improvement to UFRV but raw water turbidities above 20 NTU were problematic

· Chlorine Dioxide can be purchased and used for 100 gpm pilot studies for feasibility studies

· Chlorine Dioxide can be cost effectively tested at plant flowrates on the order of 20 MGD

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PA Acknowledgements

· Aqua, PA American Water– Pete Kusky, Plant Supervisor

– Bill Young, Plant Chemist

– Larry Wehr, Process Controls

– Marc Lucca, VP of Production

– Craig Lutz, Water Quality Specialist

– Doug Crawshaw, Production Engineer

– Bill McGinty, Manager of Treatment/QC

– Jack Walter, Division Manager

· Infilco (IDI), Siemens· Hatch Mott MacDonald (HMM)

– Josef Argenio, EIT

– Mark Tompeck, PE

Thank You

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PA

Phase 1: Head-Loss with ACTIFLO Treated WaterBackwash Occurs when Head-Loss Reaches 120 Inches

Filter’s 60 & 72 Have the Longest Run

Times

Existing PlantFilter

Date

47 60 72 GAC


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PA

· At room temperature, chlorine dioxide (ClO2) is a light sensitive gas denser than air, yellow/greenish in color, highly soluble in water, with a chlorine like odor.

Cl

OOClO2 Molecular Structure

Technical Overview

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PA Technical Overview

Chlorine Dioxide belongs to the family of chemicals known as Oxidizers. CLO2 is also a powerful disinfectant. · Ozone· Hydrogen Peroxide· Chlorine· Chlorine Dioxide

Measured by ORP potential

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PA Why Chlorine Dioxide?

· Cost effective disinfectant for regulatory compliance– declining surface water quality favors CLO2

– effective @ pH 2-10

– enhanced CxT’s for crypto and giardia

– reduces THM’s, THAA’s and AOX

– EPA approved for primary and residual disinfection

· Selective oxidant – reduces Mn / Fe, assists on particle count reduction and enhances filter runs

– Improves taste and odor, oxidizes / destroys sulfides, certain humics / fluvics / phenols

· Superior DBP control:– residuals measurable, well studied

– does not oxidize bromide to bromate; no reaction with ammonia

– does not chlorinate organics

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PA Disinfection with ClO2

· Broad spectrum biocide – bacteria, viruses, fungi, algae, mollusks and biofilm– Provides CxT credits effective for Giardia and Cryptosporidium in multiple barrier approach– lower “CxT” values versus Cl2 and chloramines– Synergy with UV (pre or post UV for wastewater and reclaim water)

· Effective pH 2 to 10– does not oxidize bromide to bromate– does not react with ammonia – is often more effective and less costly than permanganate in reducing manganese and iron concentrations

· Points of Application– ahead of chlorination or chloramination to reduce THM’s– following UV for residual and enhanced disinfection– ahead of ozone to reduce ozone demand and minimize bromate– compatible with chloramines - controls nitrification

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PAAuto Flow-Pacing “Chlorine Free”

Chlorine Dioxide Generators (1 to 110 kg/hr)

• 12% Sodium Hypochlorite

• 15% Hydrochloric Acid

• 25% Sodium Chlorite

• Chlorine in-situ on demand

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PAAuto Batch Generator –

3 Chemical

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PA

0 5 10 15 20 25 30 35 40 45 500

20

40

60

80

100

120

Reaction time (hours)

Chl

orof

orm

Con

cent

ratio

n (u

g/L)

Chlorine Dioxide Free Chlorine

Chloroform production in water containing 5 mg humic aciddosed with chlorine dioxide or free chlorine

THM Formation

Naock & Doerr 1978

“No THMs with ClO2

”

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PA Biofilm Control

· CLO2 penetrates and kills biofilm· Does not react with ammonia · Retains disinfection capability with no need to overcome

ammonia demand· Shown to reduce planktonic population by 98.72% and biofilm

population by 99.88%· Additional benefits due the chlorite ion disinfection by-product:

– retards nitrification issues

– extends life of chloramines

Walker, J.T. and M. Morales. 1997. Evaluation of Chlorine dioxide For The Control of Biofilms. Jour. Water. Sci. Tech.. 35:11 (319-323)McGuire, M.J., N. I Lieu and M. S. Pearthree. 1999. Using chlorite ion to control nitrification. Jour. AWWA. 91:10 (52-61)Gates, D. 1998. Chlorine Dioxide Handbook, Water Disinfection Series. Denver,CO: AWWA. Pp. 63 - 64.

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PA Point of Addition

· To eliminate prechlorination (thereby reducing DBP formation) · Head of treatment train

– Low demand waters

· Entry to treatment plant (in combination with coagulation)– High demand waters

· Intake (sufficient time to react)– Turbid waters

– Will not remove TOC, but improves coagulation & particle counts

· After sedimentation (reduced demand)· Before ozonation to reduce demand on ozone and to help reduce

bromate formation by ozone

Effective Use of Filter Pilot Testing and Chlorine Dioxide Demonstration Testing to Optimize...

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