PHOSPHORUS REMOVAL: TREATMENT TECHNOLOGIES AND CAPABILITIES

Jane Madden, PE, BCEE Senior Vice President

CAWPCA Fall Workshop November 14, 2014

Agenda

• Phosphorus Removal Overview • Phosphorus Regulations in Massachusetts • Six Phosphorus Removal Case Studies • Summary and Questions

CAWPCA Fall Workshop

Phosphorus Fractions In Wastewater

CAWPCA Fall Workshop

Orthophosphate fractions Acid-hydrolyzable fractions Organic fractions

mg/

L ph

osph

orus

Insoluble (retained on f ilter)

Soluble (passes throughfilter)

Direct colorimetry

Sulfuric acid digestion & colorimetry

Persulfate digestion & colorimetry

0.45 µm filter

Analyses type

How is Phosphorus Removal Achieved?

• Convert soluble orthophosphates to a solid

• Remove solid – Biological solid

(microorganism) – Chemical solid

(precipitate)

CAWPCA Fall Workshop

Biological Phosphorus Removal

CAWPCA Fall Workshop

Secondary Clarifier

Aerobic

Return Activated Sludge

Waste Activated Sludge (TP ~4-7% of organic TSS)

Primary Clarifier

Preliminary Treatment

Anaerobic

Effluent TP < 0.75 mg/L

P RELEASE P UPTAKE

Pros and Cons of Biological Phosphorus Removal

CAWPCA Fall Workshop

• Pros – Sustainable treatment process – Low O&M costs – No chemical storage and feed systems – Less sludge production – Anaerobic selector provides improved sludge settleability

• Cons – Phosphorus re-release – Cannot achieve extremely low limits – Subject to upsets (like any biological process) – Can compete with biological nitrogen removal – Some plants report dewaterability issues

Chemical Phosphorus Removal

CAWPCA Fall Workshop

Dual point is more efficient than single

point

Return Activated Sludge

Waste Activated Sludge (TP ~ 2% of organic TSS

AND TP in Chemical Sludge)

Preliminary Treatment

Effluent TP < 0.5 mg/L

Chemical (Metal Salts and Polymer)

Chemical (Metal Salts and Polymer)

(add-on or integrated process)

Effluent TP < 0.2 mg/L

Chemicals (Metal Salts) Used for Phosphorus Removal

• Iron Salts – Ferric Chloride – Ferrous Sulfate

• Aluminum Salts – Alum – Poly Aluminum Chloride (PACl)

• Calcium Compounds – Quick Lime – Hydrated Lime

CAWPCA Fall Workshop

Pros and Cons of Chemical Phosphorus Removal

CAWPCA Fall Workshop

• Pros – Lower limits can be consistently achieved – No phosphorus re-release

• Cons – High O&M Cost – Increased sludge production and associated disposal costs – Chemical sludge can be more difficult to thicken and dewater – Additional chemicals for alkalinity control – Not sustainable

Processes to Achieve Low TP Limits (0.2 mg/L or less) (case studies)

• Add-On Processes with Chemical Addition – Filtration

• Conventional sand filters • Cloth media filters • Upflow filters

– Ballasted Flocculation • ACTIFLO® • CoMagTM

• DensaDeg®

• Integrated Processes – BioMag – Membrane Bioreactors (MBRs)

CAWPCA Fall Workshop

EPA Region 1 in Massachusetts Has Pushed the Envelope on Phosphorus Removal

CAWPCA Fall Workshop

Massachusetts Communities with Phosphorus Limits <0.2 mg/L

CAWPCA Fall Workshop

Regulations have Inspired Innovation

• Upgrade under construction – EBPR (A/O process) – Aquadisks and Aquadiamonds to achieve

0.1 mg/L summer, 0.3 mg/L winter – Bid Price: $17.4 M

Charles River Pollution Control District, Medway, MA

• Originally Constructed 1978 – 4.5 mgd

• Upgraded and Expanded 1998 to 5.7 mgd – Single-stage nitrification – Disk filters TP to achieve

0.2 mg/L seasonally

CAWPCA Fall Workshop

Filtration – Cloth Media

CAWPCA Fall Workshop

• Original facility designed by CDM Smith in early 1980s

• Average Daily Flow: 1.2 mgd • Total Phosphorus

– 0.2 mg/L (April – Oct) – 1.0 mg/L (Nov –Mar)

• Process: CoMag by Evoqua • First full-scale facility in the

world • Construction Complete 2007 • Construction Cost $13M

CAWPCA Fall Workshop

Concord, MA

Concord CoMagTM Ballasted Flocculation System

CAWPCA Fall Workshop

Reaction Tanks (Polymer Addition)

Alum Addition To CoMagTM Influent Piping

Settled Sludge

Optional Polishing Magnet

Clarifiers

Magnetite Recycling Drums

Performance Test Results – December 2007

CAWPCA Fall Workshop

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

12/10/2007 12/12/2007 12/14/2007 12/16/2007 12/18/2007 12/20/2007 12/22/2007

Date

Tota

l Pho

spho

rus

[mg/

L]

Secondary Effluent

CoMag Effluent

Average tertiary effluent TP < 0.05 mg/L

Webster, MA

• Average Design Flow: 6 mgd • Total Phosphorus

– 0.2 mg/L (Apr – Oct) – 1.0 mg/L (Nov – Mar)

• Process: Actiflo by Kruger • Constructed within existing

abandoned tanks • Construction Complete:

Spring 2011 • Construction Cost: $8M

CAWPCA Fall Workshop

Ballasted Flocculation – ACTIFLO®

CAWPCA Fall Workshop

Recirculation Pumps

Treated Water

Settling Tank

Microsand

Coagulation Tank

Injection Tank

Maturation Tank

Raw Water Inlet

Sludge + Microsand

Coagulant Polymer

Hydrocyclones

Sludge

Marlborough Westerly WWTF

• Originally Constructed 1973 – 2.0 mgd

• Upgraded and Expanded 1988 to 2.89 mgd – Single-stage seasonal

nitrification • Upgraded and Expanded

2012 to 4.15 mgd – Single-stage year-round

nitrification – 0.1 mg/L (summer) – 1.0 mg/L (winter)

• Construction Cost: $27.5M • BluePro Filtration System by

BlueWater Technologies

CAWPCA Fall Workshop

Filtration – Upflow Filters

CAWPCA Fall Workshop

Dynasand Blue PRO®

Raw Water Inlet Clean

Water

Reject Stream

Wat

er

Particles

HFO- CS Grain

Fe

Fe

Fe

O

OAs

O

OPO4

3-

Facility Upgrade – Blue PRO® System

CAWPCA Fall Workshop

Filter Quad

Influent Channel

Weir Box

Effluent and Recycle Pipes

Air Control Panel

2012 Plant Performance

Description Permit/Design Values 2012 Values Flow (mgd)

Average Daily Flow 4.15 1.97

Maximum Daily Flow 7.5 4.5

Influent (mg/L)

CBOD 184 211

TSS 269 357

Phosphorus 6.1 7.9

Effluent (mg/L)

CBOD 15-25 0.89

TSS 15-30 1.82

Phosphorus – in season 0.1 0.086

Phosphorus – off season 1.0 0.13

CAWPCA Fall Workshop

Influent and Effluent Total Phosphorus (mg/L) April – October 2012

CAWPCA Fall Workshop

0

2

4

6

8

10

12

14

16

4/1/2012 5/1/2012 6/1/2012 7/1/2012 8/1/2012 9/1/2012 10/1/2012

Tota

l Pho

spho

rus (

mg/

L)

Influent Effluent

Marlborough Easterly WWTF

• Originally Constructed early 1970s – 5.5 mgd – Two-stage/two-sludge

process • Currently being upgraded

to meet TP limits – 0.1 mg/L (Apr-Oct) – 1.0mg/L (Nov-Mar)

• Two-stage process with A/O in first stage and BioMagTM in second

• Construction Cost: $44M

CAWPCA Fall Workshop

Integrated Process - BioMag

CAWPCA Fall Workshop

Upper Blackstone Water Pollution Abatement District (UBWAD) WWTF

• Serves greater Worcester, MA • 45 mgd ADF; 80 mgd MDF; 160 Peak hour • 3 Phase improvements plan completed in 2012 at a cost of

$180M

CAWPCA Fall Workshop

Facility Designed to Exceed 2001 Permit Limits Using Sustainable Process (EBNR – A2/O)

CAWPCA Fall Workshop

• Incorporated Nitrogen removal – Reduce O2 demand – Reduce chemicals for

alkalinity control • Biological phosphorus

removal • Gravity flow into and out of

treatment facility

Currently working with District to Optimize EBNR and Pilot Conventional Technologies

Process Optimization

• Conversion from caustic to magnesium hydroxide for alkalinity control

• Addition of real-time instrumentation and controls

• Operation in step feed under high flows

Pilot Studies

• Targeted addition of ferric chloride

• A2/O with supplemental carbon

• Modified Bardenpho with and without supplemental carbon

CAWPCA Fall Workshop

Innovative Technology – Advanced Biological Nutrient Recovery (ABNR)

CAWPCA Fall Workshop

ABNR Mimics the Natural Process in a Controlled Environment (PBR)

• Consumes CO2 • Releases O2

• Consumes nutrients • No chemical addition

required • Harvested algae is

potentially a beneficial product

• Can remove metals and other contaminants

CAWPCA Fall Workshop

Summary

• Each facility is unique and will have a unique solution for phosphorus removal

• Be cognizant of permit language – Push for seasonal average load or concentration – Consider regulating ortho-P vs. TP (to mitigate non-reactive P)

• Biological nitrogen and phosphorus removal are often competing reactions

• Phosphorus removal facilities can be costly to construct… • …And operate primarily due to power and chemicals

– Intermediate pumping; ancillary systems – Cost of chemicals (for coagulation and alkalinity) and increase

in sludge production

CAWPCA Fall Workshop

Questions?

Jane Madden, P.E., BCEE

CDM Smith maddenje@cdmsmith.com

CAWPCA Fall Workshop

Blue Pro

EBNR

Actiflo

BioMag

CoMag

Cloth Filters