PHOSPHORUS EMOVAL CHALLENGES AND OPPORTUNITIES · Illinois Regulatory (2012) • Phosphorus in...

Copyright 2013 HDR Engineering, Inc. All rights reserved.

PHOSPHORUS REMOVAL CHALLENGES AND OPPORTUNITIES

IWEA Nutrient Removal and Recovery Workshop Addison, IL

12 September 2013

JB Neethling

Outline

• Introduction • Phosphorus Removal • Las Vegas’ Gamble • Emerging Issues / Challenges

– Sidestream management – Dewaterability – Nutrient recovery

Illinois Regulatory (2012)

• Phosphorus in limiting nutrient in almost all IL streams

• 53 stream segments on 303(d) list • 1 mg/L for plants > 1mgd • New, upgrade, expanded facilities may get

lower limit

Bob Mosher, EPA, 2012. Illinois Nutrient Removal Recovery Workshop 2012

Nutrient Removal & Recovery Survey I

Mark Halm, 2012. Illinois Nutrient Removal Recovery Workshop 2012

Nutrient Removal & Recovery Survey II

Mark Halm, 2012. Illinois Nutrient Removal Recovery Workshop 2012

WERF Nutrients Challenge Goals • Develop and share credible scientific information about nutrients & their

bioavailability to help regulators make informed decisions

• Better understand existing mechanisms of nutrient removal and best available technologies so treatment plants can become more efficient and effective, enabling them to cost-effectively meet permit limits

Focus on nitrogen (N) and phosphorus (P)

Wastewater treatment related issues

Status: Ongoing, 5 – 7 year challenge

Investment: ~$3 million WERF funds (started in 2007)

In-kind, in-cash: >$10 million

Leveraged with additional funding, Collaboration, etc.

Nutrient Removal Challenge website: www.werf.org/nutrients

http://www.werf.org/nutrients

Nutrient Removal Challenge Strategy • Challenge is huge, Funds are limited, Knowledge is available

and growing, Need to Collaborate! • Research roadmap developed and refined with industry expert

knowledge and guidance • Volunteer experts from utilities, consultants, industry,

regulators, et al

Focus on collaboration to increase value to profession (instead of single projects)

Address fundamentals, with strong results focus

Engage stakeholders to participate in an active role

Leverage ongoing projects Use “Tom Sawyer” principle to

paint the fence together

COLLABORATION is the KEY!

Nutrient Removal Challenge NUTR1R06 – Core Team

• Collaborative team led by HDR, with AECOM + CH2M-Hill + Univ. of Washington + other Universities + Collaborators

• >30 Utilities, Universities, Consultants, and Research Organizations nationwide and abroad

• Others added as needed

• Identified and secured >$10 million in additional funds or in-kind contributions through utilities & other research

Core Team and Other Members:

• JB Neethling, HDR (principal investigator)

• Amit Pramanik, WERF

• Julian Sandino, CH2M-Hill

• H. David Stensel, University of Washington

• Roy Tsuchihashi, AECOM

• David Clark, HDR

• Stacy Passaro, Passaro

Nutrient Removal Challenge website: www.werf.org/nutrients

http://www.werf.org/nutrients

PHOSPHORUS REMOVAL

P Speciation

Total P

Soluble P Particulate P

Reactive P SRP pRP Sol NonReactive P

SNRP Particulate NonReactive P

pNRP Reactive P

SRP Acid Hydrolyzable

SAHP Organic SOP pRP

Acid Hydrolyzable pAHP

Organic pOP

Spec

ies

SNRP SRP Particulate P

12

Phosphorus Treatment Options

Chemical Biological

Fundamental Principle of Phosphorus Removal

There is no airborne (gaseous) form of phosphorus

The exception

15

Enhanced Biological Phosphorus Removal (EBPR)

• Discovery in 1960’s-1970’s that, under some conditions, activated sludge will accumulate phosphorus in excess of normal biological requirements

• Called “Luxury Uptake” • Long debated if this is a chemical or biological

phenomenon – Biological action now proven

17

Neisser Stain

WERF - VIP plant, 7/3/03

22

EBPR Requirements

• Anaerobic/aerobic sequence • Adequate supply of volatile fatty acids (VFAs)

in anaerobic zone • No free oxygen • No bound oxygen (nitrate)

23

Biological Phosphorus Removal

Anaerobic Aerobic

RAS

Clarifier

Conc

entr

atio

n, m

g/l

Time

BOD

Soluble P

24

EBPR Biochemistry Model

Time

Con

cent

rati

on

Sol P VFA

PHA, PHB

ANAEROBIC AEROBIC

25

Pontiac, MI. AO process for P removal

Biological Phosphorus Removal Zoned Design

Phoredox (AO)

3-stage Phoredox (A2O)*

Johannesburg*

Modified Johannesburg*

West Bank*

VFA

anaerobic

anoxic

aerobic

* removes TN and TP

Biological Phosphorus Removal Zoned Design

Modified (5-stage) Bardenpho*

UCT*

Modified UCT*

VIP (Virginia Initiative Process)*

anaerobic

anoxic

aerobic

* removes TN and TP

Biological Phosphorus Removal Mixed Design

SBR*

Biodenipho*

PhoStrip*

Trickling Filter with EBPR*

Nitrify

anaerobic

anoxic

aerobic

* removes TN and TP

Las Vegas - 3 stage Phoredox or mUCT

Anaerobic Zone

Pinery WWTP, CO

Anaerobic Zone

Virginia Initiative Plant, HRSD, Norfolk, VA

Biological Phosphorus Removal

• Many Process Options • Anaerobic Zone key to process • High influent rbCOD/P is desired

– carbon/VFA addition via fermentation • Process stability is key. Conditions that favor the

right PAO populations are need to be understood

• Typically achieve ~0.5-1.0 mg TP/L • Optimal reduce OrthoP to 0.02-0.05 mg P/L

Reliability of Biological Phosphorus Removal • WERF Study 2002

– HDR Engineering Inc

• Six Full scale facilities • Statistical data analysis • Field testing

VIP trend TP

0

1

2

3

Jul-99 Jan-00 Jul-00 Jan-01 Jul-01 Jan-02 Jul-02 Jan-03 Jul-03

mg/

L

Final Effluent, T-P

McDowell Creek

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 Jul-01 Jan-02 Jul-02 Jan-03 Jul-03

TP [m

g/L]

EFF, TP

Adding a Sugar waste stabilized biological phosphorus removal.

Empire

Empire - Final Effluent Total P

0

1

2

3

4

5

6

7

8

May-01 Jun-20 Aug-09 Sep-28 Nov-17

mgP

/L

FIN EFF TP

EBPR Reliability Comparison

oP below Durham VIP Nanse-

mond McDo-

well Creek

Lower Reedy

Empire

<0.5 mg/L 69% 70% 24% 94% 53%

84%

<1 mg/L 88% 82% 64% 99% 75%

99%

<2 mg/L 97% 92% 85% 100% 91%

100%

Neethling et al. (2005) Factors Influencing the Reliability of Enhanced Biological Phosphorus Removal, WERF 2005.

PHOSPHORUS CHEMISTRY

Typical Chemical Treatment Opportunities

Primary Secondary Tertiary Polish

Solids Processing

Metal salt reaction with phosphorus Old School

Al2(SO4)3.14H2O+ 2H3(PO4) = 2Al(PO4) + 3H2SO4 + 18H2O

FeCl3 + H3(PO4) = Fe(PO4) + 3HCl3

The following illustrates a “stoichiometric reaction” of Al+++ or Fe+++ with P, But actual P removal mechanism is related to hydroxide formation.

In above 1 mole of P uses 1 mole of Al or 1 mole of Fe

Hydroxide formation can be simply represented:

FeCl3 + 3H2O = Fe(OH)3 + 3 HCl Al2(SO4)3.14H2O + 3 H2O -> 2Al(OH)3(s) + 3H2SO4

Metal hydroxide removal of P found for ferric addition • Metal hydroxide formed • Co precipitation of P into hydrous ferric

oxides structure – Fe(OH)3, Fe(OH)4

-

• Surface complexation between P and metal hydroxide compounds

• Phosphorus and Iron share oxygen molecule: • FeOOH + HOPO3 = FeOOPO3 + H2O

pH 7-->

← pH 3 Scott Smith, Wilfrid Laurier University

Fresh HFO

Scott Smith, Wilfrid Laurier University

Young HFO


Aged HFO

FePO4 precipitant After 4 days. Hard !!



Phosphorus Removal

Chemical Dose

Phos

phor

us C

once

ntra

tion Initial removal - Stoichiometric

1:1 Equilibrium control – need higher dose

Break ~ 1 mg/L

Molar Dose Ratio From Tests

Slav Hermanowicz, Chemical Fundamentals of Phosphorus Precipitation, WERF Boundary Condition Workshop, Washington DC, 2006

02468

101214161820

0.01 0.1 1 10

ortho P res (mg/L)

Al/P

(mol

/mol

)

Full Scale 6.6 - 6.75

Lab data pH 6

Lab data pH 7.2

0.1

1

10

100

0.01 0.1 1 10

ortho P res (mg/L)

Fe/P

(m

ol/m

ol)

Lab data pH 6.5

Lab data pH 6.8

Lab data pH 7.2Lab data pH 8

Full Scale data

FULL SCALE PERFORMANCE

What is the “Performance”?

• What permit limit can this plant meet? – Numerical – concentration – Averaging – daily, weekly, monthly, annual

0.001

0.01

0.1

1

10

0.001

0.01

0.1

1

10

Dec-04 Jul-05 Dec-05 Jul-06 Jan-07 Jul-07 Jan-08

--

Central (all), TP

Lowest value?

“Next” Lowest value?

“Repeated” Low value?

“Average” Value?

“Reliable” Value?

1% 10% 25% 75% 90% 99% 99.9%0.1% 50%0.00

0.01

0.10

1.00

10.00

Percent of values less than of equal to indicated value

mg/

L

SE TP (all)

22

3.84%

0.040

50%

0.080

95%

0.23

Technology Performance Statistics

Neethling et al. (2009) WEF Nutrient 2009, Alexandria, VA.

Ideal Median Reliable

Factors Affecting Performance “Safety Factor” • “Normal” variations • Influent variations – Flow, load, peaks • Environmental factors – Rain, temperature • External issues – Construction, toxic dump • Unexpected events – Equipment failure,

chemical supply • Plant “upsets” – Human interface, recycle

dominoes

68

Permit Period and Reliability

Period Basis (days) Sample Permit Percentile

(%)

Reliable Percentile

(%)

5 yr Excee-dance

Max Day 1 365 99.7 99.9 1.8

Max Week 7 365 98.1 99 2.6

Max Month 30 365 91.8 95 3

Ann Avg 182.5 365 50 90 0.5

Permit Period and Reliability

Period Basis (days) Sample Permit Percentile

(%)

Reliable Percentile

(%)

5 yr Excee-dance

Max Day 1 365 99.7 99.9 1.8

Max Week 7 365 98.1 99 2.6

Max Month 30 365 91.8 95 3

Ann Avg 182.5 365 50 80 1

Exceed once a year!

Acceptable Risk?

1% 10% 25% 75% 90% 99% 99.9%0.1% 50%0.00

0.01

0.10

1.00

10.00

Percent of values less than of equal to indicated value

mg/

L

SE TP (all)

22

3.84%

0.040

50%

0.080

95%

0.23

Calculate Reliability to Meet a Permit Limit – say meet 0.2 mg/L TP

Neethling et al. (2009) WEF Nutrient 2009, Alexandria, VA.

~91%

Exceed 9% Monthly Exceedance = 5.4 times in 5yr Annual Exceedence = 0.45 times in 5 yr

Evaluate Performance

• Long term data from full scale plants – Determine 80th and 95th percentiles

• Special studies – Speciation results from grab/occasional samples

• Determine the expected achievable performance based on process understanding

P Speciation

Total P

Soluble P Particulate P

Reactive P SRP pRP Sol NonReactive P

SNRP Particulate NonReactive P

pNRP Reactive P

SRP Acid Hydrolyzable

SAHP Organic SOP pRP

Acid Hydrolyzable pAHP

Organic pOP

Spec

ies

SNRP SRP Particulate P

Phosphorus TPS Plant 50% 80% 95% 50% 80% 95% 50% 80% 95%

ChemP (multiple) 25 25 25 25 55 80 50 80 120 BioP, chem/sed/fil 29 40 54 ChemP (multiple) 40 90 140 35 60 90 70 120 180 ChemP (in AS) 90 134 203 17 47 83 71 119 196 BioP, chem/sed/filt 19 44 152 60 78 102 80 116 233 BioP, MBR 50 80 120 30 40 60 80 110 160 BioP, chem/sed/filt 30 57 119 50 71 92 83 113 177 BioP, chem/sed/filt 16 31 141 53 85 169 83 148 329 BioP, filter 40 60 78 80 120 260 110 160 270 BioP, MBR 49 498 2,522 11 15 60 51 184 1,795 BioP, filter 114 240 480 ChemP 100 300 740 60 100 199 140 310 730 BioP, filter 40 70 110 110 140 180 150 190 324 BioP/ChemP/filt 130 210 810 50 60 150 170 250 950 BioP, filter 100 216 487 80 120 190 190 310 635 BioP, filter 140 210 350 110 140 190 270 350 490 BioP, chem/filter 130 250 610 160 210 304 320 440 770 BioP 105 205 511 177 272 593 340 518 1,505 BioP, filter 230 390 642 180 220 290 400 590 890 BioP 423 662 1,200 ChemP, filter 420 652 950 40 70 140 500 750 972 BioP and chemical 651 1,364 1,762

TRP TNRP TP

Phosphorus Performance TPS (avg/min)

Species 50% 80% 90%

TRP – avg 97 200 480

TRP – min 16 25 25

TNRP – avg 75 105 180

TNRP – min 10 15 60

TP – avg 200 320 650

TP – min 30 40 55

Distribution of sRP

Adapted from: Gu, A. et al. “Phosphorus Fractionation And Removal In Wastewater Treatment- Implications For Minimizing Effluent Phosphorus,” WERF Nutrient Removal Study; Draft Report 2012.

1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

sRP,

ug/L

Ranking, %

MF MBR Fil/Fil Sed/Fil Filter BNR 50% 80% 95%

Distribution of sRP – Optimal Estimate - 5-15 ug/L


1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

sRP,

ug/L

Ranking, %


Distribution of sNRP


1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

sNRP

, ug/

L

Ranking, %


Distribution of sNRP – Optimal Estimate – 15-25 ug/L


1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

sNRP

, ug/

L

Ranking, %


Distribution of pTP


1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

pTP,

ug/L

Ranking, %


Distribution of pTP – Optimal Estimate – 10-20 ug/L


1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

pTP,

ug/L

Ranking, %


Estimated Optimal P Species in Advanced Treatment

SRP=Soluble Reactive P; SNRP = Soluble Nonreactive P pP=Particulate P TP = Total P

0

10

20

30

40

50

60

SRP SNRP pP TP

Conc

entra

tion

, ug

P/L

SIDESTREAM MANAGEMENT IS REQUIRED TO ACHIEVE LOW CONCENTRATIONS

Construct a Mass Balance

Primary Secondary Tertiary

Solids Processing

100 1

99

Construct a Mass Balance

Primary Secondary Tertiary

Solids Processing

100 150 110

40

1 10

9 100

149 99

50

Nan Mass Balance

Phosphorus Mass Balance

Durham Nanse-mond

VIP McDowell Creek

Lower Reedy

Total Recycle P 14% 86% 9% 26% 54%

Digester Recycle P 24% 86% 9% 23% 54%

Struvite - MAP

Magnesium Ammonium Phosphate

Struvite – Friend or Foe

• Magnesium-Ammonium Phosphate • Biological Phosphorus Removal increase

Struvite formation – PAO’s accumulate both P and Mg – Bring that to digester – Contact with Ammonia in digester – Supersaturate struvite

• Low pH depress formation

Why bother ?

Struvite Precipitation Reactor

Mg2+ + NH4+ + PO4

3-

CITY OF LAS VEGAS EXPERIENCE


1970

BNR History in Las Vegas - 1970

Las Vegas – 1980-1990

• Trickling Filter – BOD only • Fought EPA’s new phosphorus limit (0.5

mg/L) • Won – given short time to meet 1-2? mg/L TP • Solution – Chemical addition to Primary

– Increase capacity from 28 to 41 mgd – Meet phosphorus limit – Complete in 6 months

1999

BNR History in Las Vegas - 1999

Las Vegas – 1990-2000

• New permit: – TP 0.27 mg/L (mass loading) – NH4-N 0.67 mg/L

• Solution – New nitrifying activated sludge following TF – Add effluent filtration

Plant 3 + 4 Plant 1 + 2

Solids

BNR

Filtration

Headworks

Nitrification

BNR History in Las Vegas – 2000+

Las Vegas – 2000+

• Capacity increase by 30 mgd • Add new BNR process • Retain TF/nitrification with chemical addition

PSL

PSL

PSL

SCL

SCL

TF

TF

AB-NSCL

F D

HW

SCL

GTH

THC

ADDWC

Plant 1+2

BNR

Plant 3.4

Las Vegas Process Flow Diagram

Ferric Ferric

Las Vegas – 2011+

• Reduced Capacity to ~70 mgd needed – North Las Vegas gone away

• Limits reduced – TP - 0.17 mg/L – NH4 - 0.48 mg/L – Nitrate “optional”

• Proposed solution – Take TF offline – Convert nitrification process to NDN – Retain chemical P removal

Construction

TP in and out

0

2

4

6

8

10

12

14

Apr-03 Jun-03 Aug-03 Oct-03 Dec-03

mg/

L

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

mg/

L

BNR Inf, TP BNR Eff, TP

Process Performance

Aeration Basin Effluent and Clarifier Effluent oP

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Apr-03 Jun-03 Aug-03 Oct-03 Dec-03 Feb-04

mg/

L

BNR Eff, oP BNR Aer, oP avg

Process Performance

DEWATERABILITY OF EBPR SLUDGE

165

Hampton Roads Sanitation District, Virginia Beach, VA - Atlantic Plant

Selector online

Data Source: Hampton Roads Sanitation District, Virginia Beach, VA

MWRD, Denver, CO Robert W. Hite Treatment Facility

EBPR Pilot

Data Source: Metro Wastewater Reclamation District, Denver, CO

Biosolids dewaterability

• Due to high Mono/Di valent cation ratio? • Due to high PO4 in feed? • Other

Mass Balance – P, K

EBPR

Digest Dewater

100 / 50 0 / 20

100 / 30

100 / 0

100 / 50

Say 50/ 30

lb P / lb K

Mass Balance – P, K

EBPR

Digest Dewater

100 / 50 0 / 30

150 / 50

100 / 0

150 / 80

50/ 50

lb P / lb K

Mg++ and Ca++ uptake and released by EBPR precipitate in digester as Struvite and other precipitants

Mass Balance – P, K (round 2)

EBPR

Digest Dewater

100 / 50 0 / 50

150 / 50*

100 / 0

150 / 100

50/ 50

lb P / lb K

* In addition – the soluble K slowly increase over time

Dewatering Ongoing Research

• Impact of monovalent / divalent cation ratio • Impact of phosphate • Metal salt addition to liquid stream that ends up in

the digester • Struvite recovery • Sequestering recycle phosphorus to break “recycle”

EMERGING QUESTIONS

174

Performance Opportunities for Improvement • Improved reliability with EBPR to ~20 ug/L?

– VFA supply – Stable operation

• Improved reliability with chemical solids management

• Attenuate side stream impacts • P indexing for land application of biosolids

– All the P ends up in the solids – Bioavailable? Or not?

Phosphorus Removal/Recovery Drivers • Low PO4-P recycle required for EBPR to

function • Struvite formation nousance • Biosolids dewaterability • Product recovery opportunities


PHOSPHORUS REMOVAL CHALLENGES AND OPPORTUNITIES

IWEA Nutrient Removal and Recovery Workshop Addison, IL

12 September 2013

JB Neethling

QUESTIONS? • JB Neethling

BIOAVAILABILITY OF PHOSPHORUS

Upflow Sand Filter

Intermediate = Conventional Sedimentation

Influent

Phosphorus Bioassay Process Effluent

Michael T. Brett & Bo Li, University of Washington

BAP vs TP and TRP

02468

101214161820

P species

TP

TRP

BAP

TP

TRP BAP

Effluent (n=4)

050

100150200250300350400450500

P species

TP

TRP

BAP

TP

TRP BAP

Influent (n=4)

µg/

L

µg/

L

Brett & Li, Spokane River Interim Report, Jan 2010

Bioavailable P - Species Profile in Sedimentation/Filtration Process • Winter (a)

– No chemical upstream: • TP 2750 ug/L • BAP = 1280 ug/L

– Effluent • TP = 30 ug/L • BAP = 6 ug/L

• Summer (b) – Chemical upstream:

• TP = 470 ug/L • BAP = 280 ug/L

– Effluent • TP = 18 ug/L • BAP = 1 ug/L

Li & Brett (2012)

Relationship between Treatment and Bioavailable P

• Increased degree of treatment reduce %BAP

• Chemical addition used to achieve very low P

Li & Brett (2012)

TRP is a conservative estimate of BAP

• %BAP decrease as phosphorus concentration decrease: – Influent > Intermediate >

Effluent • %BAP decrease with

chemical addition • BAP is always less than

TRP – Use TRP as conservative

measure of BAP

Li & Brett (2012)

Key Findings – BAP Finding WQ Impact Technology Impact BAP can be measured with standard algal assay

BAP measurement may not reflect in situ availability

BAP Measurement is time consuming and complex

Chemical treatment reduce the %BAP

Treatment approach impacts the BAP fraction

Chemical addition (polishing) reduce BAP

%BAP lower in advanced treatment producing low TP concentrations

WQ impact from TP from advanced treatment processes lower

Chemical addition in advanced treatment reduce %BAP

TRP measurements exceed BAP measurements

TRP could be a conservative estimate of BAP

Measuring TRP is simpler than BAP

QUESTIONS?

PHOSPHORUS EMOVAL CHALLENGES AND OPPORTUNITIES · Illinois Regulatory (2012) • Phosphorus in...

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