combined sewer overflow (cso) treatment technology evaluation · primary treatment hydraulics...

Combined Sewer Overflow (CSO) Treatment Technology Evaluation

Bob BucherKing County DNRP-WTDTechnology Assessment Program

Fall Science Seminar

October 27, 2009

Project Background

King County CSO Program Planning

Recommendations from CSO Control Plan Review

• Conventional Primary stillremains first choice for treatment

• Pilot High Rate Sedimentation processes

Sluice Gate

Control Room &Odor Control

OverflowWeir

CSO Influent

Primary Treatment Hydraulics

Surface Overflow Rate (SOR)Volume of wastewater treated per square foot of treatment liquid surface area (gallons per day per square foot, or gpd/sf)

Treatment Process Performance

• CSO Treatment Standards– TSS– Fecal Coliform– Settleable Solids

• Water Quality-Based Permit Limits– Metals– Ammonia– Chlorine

• Sediment-Based Permit Limits

Pilot Testing of CSO Treatment Alternatives(Previous King County Experience)

Densadeg – 2001 Actiflo – 2001

Pilot Testing of CSO Treatment Alternatives(Current Test Program – West Point)

Pilot Testing of CSO Treatment Alternatives(Current Test Program – West Point)

Conventional Overflow Weir

Lamella Plates

Chemical Enhanced – addition of coagulant (PAX 18) and polymer (anionic)

Pilot Testing of CSO Treatment Alternatives(What are Lamella Plates?)

Lamella plates increase a basin’s effective settling area. Each lamella plate settler provides an effective settling area equal to that of its horizontal projection.

Source: http://www.meurerresearch.com/plate_theory.html

West Point Pilot - Test Trialso Dye Testing

o West Point Primary Comparison

o Chemical Optimization

o Capacity Testing

o Dilution Testing

o Performance Testing

o Hydrograph Testing

Chemical Optimization Test TrialTrial 13D

0

20

40

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120

0 4 8 12 16 20 24PAX 18 dose (mg/L)

% re

mov

al

Conv TSS Plate TSS Conv Turbidity Plate Turbidity

Dilution Test Trial

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100 120Influent TSS (mg/L)

% R

emov

al

CEPCCE-LamellaPCLamella

SOR: PC: 1900 gpd/sq Lamella: 19000 gpd/sfDosing: PAX-18: 16 mg/L Nalco: 1mg/L

Capacity Test Trial

≈ 3,700 gpd/sf≈ 3,700 gpd/sf

≈ 23,000 gpd/sf≈ 23,000 gpd/sf

PAX 18 coagulant = 12 mg/LAnionic polymer = 1.5 mg/L

Performance Test TrialTrial 33

0

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35

10/14/2009 11:45 10/14/2009 12:15 10/14/2009 12:45 10/14/2009 13:15 10/14/2009 13:45 10/14/2009 14:15

Time

Turb

idity

(FN

U)

Influent Conv Effluent Plate Effluent

PAX18 = 12 mg/LNalclear 7768 = 1.5 mg/L

Conv SOR = 6,800 gpd/sfPlate SOR = 23,000 gpd/sf

start influent sampling

start effluent sampling

Additional Sampling for metals, nutrients, and trace organics.

Hydrograph Test TrialPeak Run Hydrograph

0

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0:00 0:28 0:57 1:26 1:55 2:24 2:52 3:21

Time from RunStart

Flow

, gpm

Testing Schedule and Final Report

Performance / Hydrograph testing through early November.Final Report in January 2010.

Acknowledgementso King County

o CSO Program

o West Point Process Group

o West Point Process Laboratory

o West Point Maintenance Staff

o Environmental Laboratory

o CDM

Combined Sewer Overflow (CSO) Treatment Technology Evaluation

Bob BucherKing County DNRP-WTDTechnology Assessment Program

Fall Science Seminar

October 27, 2009

Pilot Testing of CSO Treatment Alternatives(Current Test Program – West Point)

INLET OUTLET

OUTLET

Flocculation Zone Sedimentation Zone