Lessons Learned in Enhanced Biological Phosphorus Removal

87th OWEA Annual Conference

Jim Gagnon, P.E., CH2M HILL

V1.0

Presentation Outline

Phosphorus Limits in Ohio

Upgrades to the Versailles, OH WWRF

WWRF Performance

EBPR Basics

11 Lessons Learned from Versailles

Where is Versailles Located?

Southwestern Ohio

Darke County (borders Indiana)

43 miles north of Dayton

Population: ~2,700

Phosphorus Limits in Ohio

Reduced in-stream phosphorus

Reduced aquatic plant growth

• Reduced in-stream

nitrogen and carbon

• Increased dissolved

oxygen

Impact of Stillwater River Basin 2009 TMDL Report

0.17

0.05

0

0.05

0.1

0.15

0.2

TP

(m

g/l

)

2004 TMDL

Report

2009 TMDL

Report

Ambient Target Total Phosphorus

(TP) Concentrations in Swamp Creek

For Village of Versailles…

• Point source controls

• Reduce Total

Phosphorus (TP)…

• Initial effluent TP limit of

1.0 mg/l

Upgrades to Versailles WWRF

Project Drivers:

• Effluent Total Phosphorus Limit of 1.0 mg/l

• Reduce/Eliminate Effluent Blending

** Plant experienced 32 excess flow diversions on

average per year (2003-2007)

Upgrades to Versailles WWRF

Upgrades to Versailles WWRF

New Oxidation Ditch Enhances

Secondary Treatment

Features:

• Provides EBPR/BNR

capability

• Separate, dedicated

anaerobic and anoxic zones

• D.O. control of aerators

• New chemical feed system

• Room for future 2nd ditch

Versailles WWRF Performance, or…

Let the Data Show…

0.0

1.0

2.0

3.0

4.0

2010 2011 2012 2013

3.26

2.36

0.75 0.66

TP

(m

g/l)

Average Effluent Total Phosphorus (TP) Concentration

(Through April 16)

Enhanced Biological P Removal (EBPR) Basics

• Removal of P exceeding metabolic requirements

Enhanced Biological P Removal (EBPR)

Luxury P Removal

Excess P Removal

Bio-P Removal

• Mediated by specialized heterotrophs called

Phosphorus Accumulating Organisms (PAOs)

Anaerobic Zone DO, NO3

Aerobic (DO)

P Release

PHB

Polyphosphate

CO2 + H2O O2

Cell

Synthesis

Energy (Ed)

Excess

P Uptake

PHB: Poly-β-hydroxybutyrate

Rapidly

Biodegradable

Substrate (VFAs)

PHB

Poly-

phosphate

Energy (Ei)

Enhanced Biological P Removal (EBPR) Mechanism

EBPR Mechanism

Aerobic Anaerobic

• VFA uptake &

storage

• P release

• Stored ‘Food’

oxidized

• Excess P Uptake

• Cell synthesis

Waste Sludge

Loaded with P

Starving

(Battery discharging)

Feeding

(Battery charging)

RAS

Anaerobic Aerobic

Ortho-P

3 x Infl. Ortho-P

BOD PHB

Storage

BOD Oxidized

Concentrations

in Bioreactor

Location in Bioreactor

Net P

Removal

Anaerobic/Oxic (A/O) Process Configuration

Lesson 1: Multiple Anaerobic Zones Give PAOs Best Opportunity to Function

• Well-mixed

• Constructed walls

• Single compartment with

baffles

• Provide adequate HRT

Lesson 2: Solids Retention Time Control Provides More Complete Picture than MLSS Control

BIOREACTOR

MLSS QINF QEFF

QWAS, CRAS

= QINF - QWAS VBIOREACTOR

VBIOREACTOR x MLSS

SRT x CRAS QWAS =

Target SRT

EBPR

SRT NITRIFICATION

SRT

Lesson 2: Solids Retention Time Control Provides More Complete Picture than MLSS Control

Lesson 3: Maintain Integrity of Anaerobic Zone to Promote PAO Growth

Anaerobic zone is crucial for PAO selection

Need to ensure

Lesson 4: Maintain Low D.O. in the Aerobic Basin to Promote Denitrification

AERATOR

D.O. TRANSMITTER D.O. PROBE

Lesson 5: Maintain Low Sludge Blankets to Limit Phosphorus in Clarifiers

TELESCOPING VALVE

SLUDGE DRAWOFF

PIPES

• New tank volume of

640,000 gal

• Retained 3 existing

digesters

• Limit anaerobic conditions

during decant

• Decant small volumes

directly to the aerobic

zone of oxidation ditch

Lesson 6: Operate Aerobic Digester to Limit Phosphorus Release

Lesson 7: Use ORP to Monitor Aerobic Digester

DIGESTER ORP AND

D.O. PROBES WITH

FLOAT

Lesson 8: Monitor and Handle Wet Weather Flows to Maintain EBPR

• Wet weather flows:

Dilute in substrate

Higher in DO

• Existing ditch and

clarifiers reused to

provide wet weather

storage

Lesson 9: Prepare for Excursions

• Adsorption

• Ion exchange

• Membrane filtration

• Filtration

• Enhanced (ballasted)

sedimentation

• Chemical addition

Lesson 9: Prepare for Excursions

ALUM STORAGE ALUM DOSING POINT –

OXIDATION DITCH

EFFLUENT WEIR

Lesson 10: Maintain Records and Use Data to Understand How EBPR is Operating

Influent:

Volume, D.O., pH, SS, CBOD5, NH3

Bioreactor:

D.O., pH, MLSS, SVI, MLVSS, F/M

Return Sludge:

pH, SS, Volume Wasted, % Solids, % VS

Effluent:

pH, D.O., NH3, SS, CBOD5, TN, TP

Digesters:

% solids, % VS

Digester Supernate:

NH3, CBOD5, ORP, TP, Volume

Lesson 10: Maintain Records

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WAS

TARGET SRT = 20 DAYS

March 2013 Data

Lesson 10: Maintain Records

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/l)

WAS SRT-7DMA

TARGET SRT = 20 DAYS

March 2013 Data

Lesson 10: Maintain Records

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T (

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llo

ns)

SR

T (

da

ys

) o

r To

tal-

P (

mg

/l)

WAS Total-P SRT-7DMA

TARGET SRT = 20 DAYS

March 2013 Data

Lesson 10: Maintain Records

0.29 0.52 0.97 0.46

0

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20,000

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r D

EC

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T (

ga

llo

ns)

SR

T (

da

ys

) o

r To

tal-

P (

mg

/l)

WAS Total-P SRT-7DMA

TARGET SRT = 20 DAYS

March 2013 Data

Lesson 10: Maintain Records

0.29 0.52 0.97 0.46

0

10,000

20,000

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ys

) o

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tal-

P (

mg

/l)

WAS DECANT Total-P SRT-7DMA

TARGET SRT = 20 DAYS

March 2013 Data

Lesson 11: Develop a “TP Compliance Strategy” to Ensure Permit Limits are Achieved

Obtain 24-hr composite effluent sample and measure Ortho-P.

Is

Ortho-

P

In Conclusion…

• EBPR in Ohio is relatively new and becoming

more common

• New requirements require effective management

of the treatment process to achieve permit limits

• Operators can use their existing knowledge

• Designers must provide flexibility

• Approach the process as a full-scale laboratory…

Allows for new ideas and for hands-on

optimization

Questions?

Jim.Gagnon@ch2m.com

513-587-7078

Lessons Learned in Enhanced Biological Phosphorus Removal