12/5/2018

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Treatment Intensification for Resource Recovery: Advances in 

Granules and MembraneBioreactor Technologies

Wednesday, December 5, 2018

12:00‐2:00 pm ET

How to Participate Today 

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Today’s Moderator

Christine Radke, PMPResearch Program DirectorThe Water Research Foundation

AgendaTime Presentation Speakers

12:00 pm Welcome and Introductions Steven Massa, WEFChristine Radke, WRF

12:05 pm National Science Foundation’s GOALI Projects and MOU with the Water Research Foundation

Karl Rockne, NSF

12:15 pm Bioaugmentation of activated sludge with high activity nitrifying granules/flocs: population selection, survival, biokinetics (TIRR3C15)

David Stensel and Mari Winkler,University of Washington

12:45 pm Advancing the oxygenic photogranule process for energy positive wastewater treatment (TIRR4C15)

Chul Park, University of Massachusetts‐Amherst

1:15 pm Biofilm‐enhanced anaerobic membrane bioreactor for low temperature domestic wastewater treatment (TIRR5C15)

Steven Skerlos, Lut Raskin, andTim Fairley, University of Michigan

1:45 pm Q&A All

2:00 pm Adjourn

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National Science Foundation and WRF’s Co‐Funded Research

Karl Rockne, Ph.D., PE, BCEEProgram DirectorEnvironmental Engineer ProgramDivision of Chemical, Bioengineering, Environmental and Transport SystemsNational Science Foundation

Bioaugmentation of activated sludge with high activity nitrifying granules/flocs: population selection, survival, biokinetics

H. David Stensel, Ph.D., PE, BCEE, WEF FellowProfessor EmeritusCivil & Environmental EngineeringUniversity of Washington

Mari Winkler, Ph.D.Assistant ProfessorCivil & Environmental EngineeringUniversity of Washington

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December 5, 2018Professor David StenselProfessor Mari Winkler

University of Washington

Bioaugmentation of activated sludge with high activity nitrifying granules/flocs: population

selection, survival, biokineticsWRF TIRR3C15

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University of Washington Project NSF/WRF GOALI

1. Bioaugment nitrification with nitrifying granules for low SRT continuous flow systems

2. Convert continuous flow systems to granular/floc activated sludge with nitrification, N removal, and possibly EBPR

Professor H David StenselProfessor Mari WinklerProfessor David StahlMaxwell Armenta, MSCE studentBao Quoc, PhD Student – NSFBob Bucher, King CountyPardi Sukapanpotharam, KC

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Agenda

• Granular sludge characteristics and selection

• Bioaugmentation process description

• Project Status

• Sidestream pilot system treatment performance

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Granular sludge is more compact, settles faster, and thickens better than flocculent sludge

Parameter Flocs GranulesMorphology Loose, irregular Regular, compact, smoothParticle size Small (<400 um) Large (0.5 - 3 mm typical)Sludge Vol. Index (SVI) ~120 mL/g 20-50 mL/gSettling velocity Slow (~1 m/hr) Fast (>10 m/hr)SVI5min / SVI30min ~2.0 (slow thickening) 1.0 - 1.1 (rapid thickening)

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Fundamental selection mechanisms for granules over flocs demonstrated in Nereda® SBR process

Settle period(<10 min)

Top of bed:Flocs wasted

Bottom of bed:Granules retained

Hydraulic selection by short settling times 

‒ Granules settle faster than floc

‒ Upper liquid wasted with slower settling floc

Food competition ‐Granules get preferential access to food during upflow anaerobic feeding

High F/M feeding provides diffusion  gradient to allow substrate uptake deep in the granules

Advantages of Granular Sludge Biological Nutrient Removal

• High mixed liquor concentration (in range of 8,000 mg/L)

• Less tank volume

• Biological nitrogen and phosphorus removal in simpler flow scheme

• Less energy

• Increase capacity and/or nutrient removal with less capital cost for retrofits

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PrimaryEffluent

Aeration Tank(3 hr)

Floc/GranuleSeparator

Waste sludge

Return Granular Sludge

Return Sludge

Clarifier

Sidestream granule Sequencing Batch

Reactor

Waste Granules

1.5 gpmStaged Anaerobic

Tanks(36 / 16 / 36 min)

NaAc

SecondaryEffluent

ScreenedCentrate

UW Bioaugmentation System with Sidestream Nitrifying Granular Activated Sludge

1. Uncoupled granular and floc SRT2. Anaerobic/Aerobic with SND

PAOsGAOs

NitrifiersNH3-N + O2

NO2-N/NO3-N

N2

PO4-PAnaerobic

Aeration and SND

PAOs

NitrifiersSoluble BOD

Anaerobic feeding

Aerobic

Anoxic

PAOs = phosphorus‐accumulating organismsGAOs = glycogen‐accumulating organisms

PO4-P

GAOs

• Same carbon used for PAO/GAO growth and denitrification• DO controlled to provide simultaneous nitrification/denitrification• Denitrification provides alkalinity for full nitrification of centrate

Anaerobic‐aerobic operation provides granules with EBPR and simultaneous nitrification/denitrification

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General Aims of ProjectI. Demonstrate and evaluate effectiveness of nitrification bioaugmentation by the 

addition of nitrifying granular activated sludge to mainstream treatment• Growth of aerobic granules on centrate

• Preferred operating conditions

• Survival and growth of granules in mainstream

• Kinetics and biopopulation characteristics

II. Demonstrate and evaluate the ability to favor AOB over NOB and accomplish short‐cut nitrogen removal in sidestream and  mainstream

• Operating conditions

• Ability to uncouple granule and flocculent sludge

• Biopopulation characteristics

15Dave Stensel

Test systemsand data Collection Design appl.

Microbial andGranule character.Kinetics, models

Mari Winkler

ScientificAdvisorMicrobialEcology

Dave Stahl

Project Status

• Start up and successful long‐term operation of sidestream reactor 

• Evaluating effects of important sidestream operating factors

Feed COD:NSRTFeeding COD gradient (short versus long feed period)DO controlSettling time

• Testing granular/floc separator designs

• Mainstream in fabrication and installation by King County 

• Start up planned for first week in January 2019

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Pilot Plant SidestreamCentrate Treatment Granular Growth SBR

1‐ft diameter8‐ft liquid depth50% decant depth6‐hour cycle fine bubble diffuser

Pilot Sidestream Operation 4 cycles/day6‐hr per cycle

Process air / N2

Effluent

Waste granules to mainstream

COD Acetate

SettledCentrate

Sec. Effl. Dilution

Anaerobic Aerobic Settle Decant Anoxic Total(min) (hr) (min) (min) Idle (hr)

Step Time 55 4.5 7 3 25 6Premix, N2 5

NaAc Feed 10Air/Mix 5

Centrate, Sec. Effl.

Feed 15

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Seeded the sidestream pilot unit with 2.0 ft of 425 um screened King County South Plant mixed liquor

• EBPR anaerobic/aerobic process

• Mixed liquor had about 12% baby granules with PAOs

Start up strategy

• Prevent acetate leakage into the aerobic period• Increase acetate load as PAO activity increases

• Promote simultaneous nitrification/denitrification• Aeration DO control (~1.8 to 2.2 mg/L)

• Avoid high effluent NO2/NO3• Increase proportion of centrate feed as COD load is increased• Aim for COD:N feed ratio of 4.0 or less for short cut nitrogen removal 

• Minimize NO3/NO2 remaining at start of acetate feed

• Seed with baby granules from King County South Plant

• Gradually decreased settling time

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Decreasing settling time after start up increased average granule size 

(7 min settling time, Solids < 12m/hr settling velocity in effluent)

Example of cycle performance (Day 163) Reactor Parameters

Influent NH3‐N160 mg/L

MLSS12,300 mg/L

VSS/TSS73%

P/C Ratio0.51 mol/mol

Temperature23°C

SRT~30 days

Some ResultsExample of weekly profile data

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Average Performance(June ‐ September, 2018)

Parameter Units June July August SeptInfluentNH3-N loading rate g/L-day 0.46 0.34 0.36 0.38Feed COD:N ratio g/g 2.7 3.4 3.5 3.5ReactorSRT, 28-day average days 86 57 40 41Average Granule Size mm 1.24 1.26 1.10 1.16MLSS mg/L 14,900 13,600 12,500 12,400SVI30 mL/g 38 38 31 26EffluentNH3-N mg/L 51.9 2.4 3.7 5.9NO2-N mg/L 11.2 12.1 0.2 0.4NO3-N mg/L 0.9 11.2 7.3 10TSS mg/L 179 102 72 72

Nitrogen Removal  Performance(June ‐ September, 2018)

Parameter Units June July Aug. Sept.Inorganic N removal % 71.8 84.2 93.3 90.7NH3-N Oxidized % 78.9 98.5 97.9 96.5

SND % 91.5 85.2 94.4 93.3COD:N-removed ratio gCOD/gN 3.5 3.5 3.7 3.7

Short Cut Nitrogen Removal (NO2 reduction instead of NO3 reduction)Indicated by low COD:N ratio and low effluent NO3-N.

For acetate:NO3-N reduction COD:N is 6.0 – 6.5 g/gNO2-N reduction COD:N is about 3.6 – 3.9 g/g

Assumed 0.024 gN/gCOD for biomass synthesis

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• Centrate sidestream treatment reactor sustained growth of nitrifying granules with 95+% NH3‐N removal

• Seeding with harvested granules aided start up

• Decreases in settling time selected for mostly granules 

• Granules had settling velocity > 12 m/hr

• Short‐cut nitrogen removal observed 

• SND efficiencies were 84‐94%

Summary

Acknowledgements

King County Dept. of Natural Resources and Parks, Wastewater Treatment Division / Technology Evaluation Program 

Graduate Student Research Fellowship

National Science Foundation

Water Research Foundationformerly Water Environment & Reuse Foundation, formerly Water Environment Research Foundation

(project number TIRR3C15)

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GOALI/WERFBIOAUGMENTATION OF ACTIVATED SLUDGE WITH HIGH ACTIVITY

NITRIFYING GRANULES/FLOCS: POPULATION SELECTION, SURVIVAL, BIOKINETICS

PhD student: Bao Nguyen QuocUniversity of Washington Dr. Mari Winkler Dr. Dave StahlDr. Dave Stensel

Projected dissolved inorganic nitrogen loads 

U.S. Census Bureau, 2016DoE WA, 2014

https://www.seattletimes.com/seattle‐news/data/seattle‐once‐again‐nations‐fastest‐growing‐big‐city‐population‐exceeds‐700000/

GRANULERUSH ERA

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What is a baby granule?• Shows a granular morphology

• With size > 212 µm

Granules retained on 212 µm sieve Puyallup ML

Microscopic imagePuyallup ML

0.2 mm

Baby Granules used as seed sludge for pilot

Puyallup 1

Puyallup 2

Henderson East 1Henderson East 2

Henderson West

Clark CountySouth Plant

West Boise (South)

Durham 2

Idaho Falls

CashmereCrooked Creek

City of KalispellPocatello

Chambers Creek

R² = 0.6935

0

10

20

30

40

50

60

70

80

90

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

% G

ran

ule

s

SVI30/SVI5

Correlation of % Granules to SVI30/SVI5

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MLSS: 14.8 g/LMLSS: 15.2 g/LMLSS: 6.8 g/L

2/24/2018 (Day 0) 4/24/2018 (Day 59) 6/28/2018 (Day 124)

ImagesfromMaxwellArmenta

Research on different granules sizes

Why do we need to care about different granule sizes?

• Size not homogenous 

• How does microbial activity partitions between granules?

• What is the best granule size?

Dynamic granule sizes

0%

10%

20%

30%

40%

50%

60%

70%

80%

0 19 33 47 61 75 89 103121135 149163 177191 212240

Percentageofgranulesize,%

Days

2360um 2000um1700um 1400um1180um 1000um850um 600um

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Substrate profile

Carbon removal

(COD + O2  CO2 + H2O)

Nitrification

(NH4 + O2  NOx )

P and N removal

(COD + NOx + PO43‐ N2 + CO2 + H2O + poly‐P)

Ammonia loading and removing rate

0

20

40

60

80

100

120

3121926334047546168758794

103

114

121

128

135

143

149

156

163

170

177

184

191

198

208

215

227

234

240

247

Nitrogenloading,gN/day

DaysNH3‐Nfedperday

NH3_N‐oxidized Approx.NremovedbySND Approx.NH3‐NforSynthesis

1.Rapidchange– 73days 2.Peak– 87days

3.Recent– 197days

DatafromMaxwellArmenta

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Sequencing: Nitrospira (NOB)

0

0.008

0.016

0.024

0.032

73 87 197 73 87 197 73 87 197

Relativeabundanceofreads,%

Operationdays

Small212‐ 425𝝁𝒎

Big>1180‐ >1400μm Mixedliquor

NOB tend to dominate small granules

Sequencing: Nitrosomonas (AOB)

0

0.3

0.6

0.9

1.2

1.5

1.8

73 87 197 73 87 197 73 87 197

Relativeabundanceofreads,%

Operationdays

Small:212‐ 425𝝁𝒎

Big:>1180‐ >1400μm MixedliquorAOB tend to dominate 

small granules

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qPCR: amoA genes at different granule sizes

y=6/x

0.00

0.01

0.02

0.03

0 500 1000 1500Surfacearea/volumeratio,

m2/m

3Granulediameter,µm

𝑽 𝟒𝟑

𝝅𝑹𝟑 𝑺 𝟒𝝅𝑹𝟐

Volume Surfacearea𝑺𝑽

𝟔𝑫 𝒚

𝟔𝒙

Surfacearea/volumeratio Function

0.E 00

2.E 05

4.E 05

6.E 05

8.E 05

1.E 06

212 - 425 425 - 600 600 - 850 850 - 1180

num

ber

of a

moA

cop

y ge

ne/m

gwet

bio

mas

s

Granule size, μm

Surface area/volume ratio versus amoA genes

y=4E+07x‐ 32124R²=0.9983

0.E+00

2.E+05

4.E+05

6.E+05

8.E+05

1.E+06

0 0.01 0.02

amoAcopygene

numbers/mgwetbiomass

Surfacearea/volumeratio,m2/m3

y=6/x

0.00

0.01

0.02

0.03

0 500 1000 1500

Surfacearea/volumeratio

Granulediameter,µm

0.E 00

2.E 05

4.E 05

6.E 05

8.E 05

1.E 06

212 - 425 425 - 600 600 - 850 850 - 1180

num

ber

of a

moA

cop

y ge

ne/m

gwet

bio

mas

s

Granule size, μm

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Ammonia oxidization rate versus amoA genes

0.E+00

2.E+05

4.E+05

6.E+05

8.E+05

1.E+06

0 5 10 15am

oAcopygene

numbers/mgwetbiomass

Ammoniaoxidizingrate,mgN/mgVSS.h

0

3

6

9

12

212‐425 600‐850 >1400

Ammoniaoxidizing

rate,m

gN/m

gVSS.h

Granularsize,µm

0.E 00

2.E 05

4.E 05

6.E 05

8.E 05

1.E 06

212 - 425 425 - 600 600 - 850 850 -1180

1180 -1400

num

ber

of a

moA

copy

ge

ne/m

gwet

biom

ass

Granule size, μm

MLSS: 14.8 g/LMLSS: 15.2 g/LMLSS: 6.8 g/L

2/24/2018 (Day 0) 4/24/2018 (Day 59) 6/28/2018 (Day 124)

ImagesfromMaxwellArmenta

Seed sludge microbial community composition

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16S rRNA gene sequencing data:South Plant

0%

20%

40%

60%

80%

100%

Flocs Granules

Relativeabundanceofreads,%

Others

Unclassified_NS1112_marine_groupZoogloea

Turneriella

Unclassified_Bacteria

Candidatus_Competibacter

RelativeDechloromonas

Unclassified_Chitinophagaceaeuncultured

Unclassified_Bacteroidia

Candidatus_Accumulibacter

Unclassified_BurkholderiaceaeAcidovorax

Unclassified_envOPS_17

Flavobacterium

5.3% of PAO Accumulibacter3.3% of relative Dechloromonas3.1% of GAO Compactibacter

16S rRNA gene sequencing data: Westpoint pilot

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

73 87 197

Relativeabundanceofreads,%

Days

RelativeDechloromonas

Candidatus_Accumulibacter

Candidatus_Competibacter

Flavobacterium

uncultured_Spirochaetaceae

Unclassified_Chitinophagaceae

Unclassified_Burkholderiaceae

Unclassified_Bacteria

Unclassified_Flavobacteriaceae

Unclassified_Bacteroidia

Unclassified_AKYH767

Unclassified_Lentimicrobiaceae

Dokdonella

Unclassified_Saprospiraceae

Unclassified_Betaproteobacteriales

Others

6.4% of PAO Accumulibacter28.3% of relative Dechloromonas6.7% of GAO Compactibacter

5.3% of PAO Accumulibacter3.3% of relative Dechloromonas3.1% of GAO Compactibacter

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Sequencing: PAOs

0

10

20

30

40

50

73 87 197 73 87 197 73 87 197

Relativeabundanceofreads,%

Operation,days

212‐ 425𝝁𝒎 >1180‐ >1400μm Mixedliquor

Aerobic PAOs? dPAOs?

qPCR for Accumulibacter

- HigherPAOs16SrRNAgenecopynumberinsmallgranules

- AerobicPAOs?

- Acetateandoxygencanpenetratebetterintosmallgranules‐>creatingabetterenvironmentforPAOstothrive

0.E 00

2.E 07

4.E 07

6.E 07

8.E 07

1.E 08

212 - 425 425 - 600 600 - 850 850 - 1180 1180

num

ber

of P

AO

s 16

S rR

NA

gen

e co

py

gene

/mgw

et b

iom

ass

Granule diameter, µm

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Nitrate & Nitrite reduction rate

Denitrification capacity higher in the big granules 

Bigger granules have more anoxic volume fraction => favoring dPAOs

0

1

2

3

4

212‐400 600‐850 >1400

NOxreductionrate,

mgN/m

gVSS.h

Granulessize,micrometers

Nitrate_NO3‐

Nitrite_NO2‐

What is the optimal granule size?

0

2

4

6

8

10

12

212‐400 600‐850 >1400

Nitrogenreduction/oxidization

rate,m

gN/m

gVSS.h

Granulessize,micrometers

Nitrate_NO3‐

Nitrite_NO2‐

Ammonium_NH4+Ammonia oxidization rate is higher in the smaller granule.Denitrifying rate is higher in the bigger granules

Best size for SND

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• Higher surface area/volume ratio higher amoA copy gene numbers 

higher ammonia oxidizing rate

• AOB and NOB are dominant in the small granules

• Accumulibacter tends to be dominant in the small granules (maybe aerobic PAO?)

• Denitrification capacity was higher in the big granules.

Summary

Thank YouKing County & University of Washington

Water Research Foundation(project number TIRR3C15)

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Advancing the oxygenic photogranule process for energy positive wastewater treatment 

Chul Park, Ph.D.

Associate Professor and Graduate Program Director

Department of Civil & Environmental Engineering

University of Massachusetts ‐ Amherst

Advancing the Oxygenic Photogranule (OPG) Process for Energy Positive Wastewater

Treatment

Chul Park, Ph.D.

Department of Civil and Environmental Engineering, University of Massachusetts Amherst

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Acknowledgement

• Dr. Caitlyn Butler @ UMass Amherst

• Dr. Christopher Wilson @ Hampton Roads Sanitation District

• Drs. Kim Milferstedt and Jérôme Hamelin at INRA-LBE

• Dr. Jangkyu Kim and others @ BKT Co., Ltd.

• Graduate students working on OPGs: Adam McNair, Ahmed Abouhend, Abeera Ansari, Camilla Kuo-Dahab, and Joseph Gikonyo

Synopsis

• Phototrophic granules (photogranules) can be

generated from transformation of activated

sludge under hydrostatic conditions

• Oxygenic photogranules (OPG) can treat

wastewater without aeration

• The oxygenic photogranule (OPG) process

can recover chemical energy in wastewater

• Need to advance the development of the OPG

process for real-world application

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Wastewater Treatment: Energy Opportunities

• Chemical (calorific) energy in wastewater

6-8 MJ/m3 wastewater (2.2 KWh/m3)

= (0.5kg COD/m3) (12-15 MJ/kg COD)

In the USA alone, 50–100 billion kWh per year, equivalentof energy from burning 30-60 million barrels of oil eachyear.

This is renewable energy!!!

Wastewater Treatment: Energy Challenges

• Energy intensive– 0.6 KWh/m3 wastewater (~2% of national energy)

– Up to 60% of this is for aeration

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Energy Yielding Wastewater Treatment

• Recover chemical energy in wastewater

• Use less energy to treat

• Currently, there is no effective way to achieve these goals

• Wastewater treatment works are currently energy consumers

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Algae-based Wastewater Treatment

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Microalgae Bacteria Effluent &biofeedstock

CODO2

Sunlight

COD

CO2

O2 CO2

O2 CO2

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Algae-based Wastewater Treatment: Challenges

• Algae do not usually aggregate

Ineffective separation of algae from water

Recycling and harvesting of biomass?

• Suspended growth & need of light!

Shallow ponds or lagoons

• Engineering challenges

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Source of photo: Thief River Falls, MN

Source of photo: Algae Biomass Summit 2017

The OPG Process for Aeration-free Wastewater Treatment

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Original Finding of OPGs

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Park & Dolan (2018) U.S. Patent

Lab windowsill

Milferstedt et al. (2017) Sci. Rep

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Plant location

Biological Process

(CAS* or BNR**)

Aeration basin configuration (covered or open basin)

Solids retention

time (SRT)

Incubation start date

First day of compaction & aggregation/

green biomass

Amherst, MA, USA

BNR, occasionally

CASOpen 10-15 days 11-Dec-14 3/5

Hadley, MA, USA

CAS Open 10 days 18-Nov-14 2/7

Springfield, MA, USA

BNR Open ~20 days 6-May-14 2/7

Northampton, MA, USA

BNR Open ~10 days 6-May-14 2/7

Deer Island- Winthrop, MA,

USA

CAS- pure O2

Covered 1-2 days 20-Jul-14 3/18

Narbonne, France

BNR Covered >20 days 26-Feb-14 2/5

Ornaisons, France

BNR Open >30 days 28-Jan-15 5/5

Neuchâtel, Switzerland

BNR Covered ~5 days 19-May-14 1/7

First appearance

of a biogranule

Mature biogranule

10

7

30

19

21

19

37

11

Milferstedt et al. (2017) Sci. Rep

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Universal Phenomenon

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Develop the OPG-based Process for Wastewater Treatment

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Removal of COD without Aeration

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0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

Total C

OD (mg/L)

Operation Period (day)

Influent

R1 Effluent

R2 Effluent

Abouhend et al. (2018) ES&T

NSF GOALI and WRF

64

Year 1 Year 2 Year 3 Aim #1. Elucidate the granulation phenomenon in reactor operation

Aim #2. Engineer the light pattern to advance the OPG process

Aim #3. Investigate the feasibility of the OPG process for municipal wastewater treatment

 

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Hydrostatically Formed vs. Reactor OPGs

65

Hydrostatic

Reactor

Hydrostatically Formed vs. Reactor OPGs

66

Abouhend et al. (2018) ES&TPanels A to E (during batch): day 0 → day 4This happens in the presence of mixing!

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67

Enrichment of Motile Filamentous Cyanobacteria

Milferstedt et al. (2017) Sci. Rep

But Filamentous Cyanobacteria Do Not Always Guarantee Photogranules

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67

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0

2

4

6

8

10

12

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15 20 25 30

Chl a (mg/L)

VSS (mg/L)

Static cultivation (d)

VSS

Chl a

Symbiosis Due to Key and Limited Substrates?

69

Hetero. Photo.

O2

CO2

Limitation of Nitrogen

70

Kuo‐Dahab et al. (2017) ES&T

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Effect of Shear on Photogranulation

N (rpm) G (s-1) Re (× 103) η (μm)

50 20 2.2 222

100 58 4.4 132

300 299 13.1 58

Table 1. Speed of mixing and resulting hydrodynamic conditions used in three SBRs.

Abouhend et al. (in preparation)

Effect of Shear on COD Removal

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Balance of Energy for Selection Pressures

73

Gikonyo et al. (in preparation)

Energy Recovery via OPG Biomass Growth

74

Biomass yield (OPG):

0.6-0.7 mg VSS/mg COD

1.2-1.3 mg COD/mg COD

Biomass yield (activated sludge):

0.3-0.6 mg COD/mg COD

Aeration↓ + Recovery of COD

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Lessons from the Recent OPG Pilot

75

• The first 500 L OPG pilot: March 26 till June 4, 2018 (Daejeon, Korea)

0

20

40

60

80

100

120

140

0 20 40 60 80

Light Intensity (klux)

Operation (days)

avglight

0

5

10

15

20

25

30

35

0 20 40 60 80

Water Temperature (Deg C)

Operation (days)

avg T

max T

76

0

200

400

600

800

1000

1200

1400

0 10 20 30 40 50 60 70 80

MLSS (m

g/L)

Operation (days)

Eff

0

20

40

60

80

100

120

140

160

180

0 10 20 30 40 50 60 70 80

sCOD (mg/L)

Operation (days)

inf

Eff

Photoinhibition underNatural Sunlight

0

20

40

60

80

100

120

140

0 20 40 60 80

Light Intensity (klux)

Operation (days)

avglight

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Conclusions

• Formation of granules under conditions that are, based on conventional knowledge, highly unlikely to support granulation

Hydrostatic conditions

In turbulently mixed bioreactor operations

• Photogranules formed under two different conditions shared similar properties

• Photogranules were formed by enrichment of motile filamentous cyanobacteria

• Balance of energy: Chemical, Light, and Hydraulic energies

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Conclusions

• Achieved the removal of COD and nitrification without aeration!

• The OPG process shows the potential to recover chemical energy in wastewater and solar energy in the form of easily separable biomass

• The first 500 L outdoor pilot taught new lessons

Seeding with large dilution works

Need to overcome photoinhibition, if sunlight is used

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Fate and Dynamics of EPS during Photogranulation

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Kuo‐Dahab et al. (2017) ES&T

Biofilm‐enhanced anaerobic membrane bioreactor for low temperature domestic wastewater treatment

Steven Skerlos, Ph.D.Professor of EngineeringUniversity of Michigan

Lut Raskin, Ph.D., WEF Fellow, AAM FellowProfessor of EngineeringUniversity of Michigan

Timothy FairleyGraduate Research AssistantUniversity of Michigan

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Caroline Van SteendamEnvironmental Eng. Graduate Student

Tim FairleyEnvironmental Eng. Graduate Student

Nishant JalgaonkarMechanical Eng. Graduate Student

BIOFILM‐ENHANCED ANAEROBIC MEMBRANE BIOREACTOR FOR LOWTEMPERATURE DOMESTIC WASTEWATER TREATMENT

Steve SkerlosProfessor

Lut RaskinProfessor

December 5, 2018

Adam SmithProfessor

USC(Ph.D. UM)

Grants:WRF – U2R15 – Next Generation Anaerobic Membrane Bioreactor Development Utilizing 3D‐PrintingNSF – CBET 1604069 – WERF: Biofilm‐Enhanced Anaerobic Membrane Bioreactor for Low Temperature Domestic Wastewater TreatmentWE&RF – TIRR5C15 – Life Cycle Assessment and Analysis of Biofilm Enhanced Anaerobic Membrane BioreactorWERF – ENER4R12 – Low Energy Alternatives for Activated Sludge – Advancing Anaerobic Membrane Bioreactor Research

WRRF – 10‐06D – Anaerobic Membrane Bioreactors as the Core Technology for a Low Energy Treatment Scheme for Water ReuseNSF – CBET 1133793 – Low‐temperature Anaerobic Membrane Bioreactors for Sustainable Domestic Wastewater Treatment

Drawbacks of conventional domestic wastewater treatment

Land Application

Landfill

Primary Clarification

Aeration Basin

Secondary Clarification

Disinfection

Anaerobic Digestion

Accounts for 45‐60% of energy demand for treatment

Produces significant residuals

Intensive land area requirement

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Can anaerobic treatment be implemented in mainstream wastewater treatment?

Challenges• Solids/liquid separation• Heating for optimal performance

o Only works in warm climates• Poor effluent quality

Upflow Anaerobic Sludge Blanket (UASB)

Benefits• No aeration required• Biogas recovery• Smaller footprint

Biogas

Anaerobic membrane bioreactor (AnMBR) is an emerging approach to energy recovery from wastewater

AnMBR

Cogeneration

Land Application

Landfill

No aeration – low energy

Produces minimal residuals

Smaller footprint

Smith, A.L., L. B. Stadler, N.G. Love, S. J. Skerlos, and L. Raskin, 2012, Perspectives on Anaerobic Membrane Bioreactor Treatment of Domestic Wastewater: A Critical Review, Bioresource Technology, 122, 149‐159.

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Must answer important questions before AnMBRtreatment of domestic wastewater will be implemented

1. Can anaerobic treatment performance be improved, especially at low temperatures?

2. Is AnMBR technology cost and environmentally advantageous to conventional treatment technologies?

Must answer important questions before AnMBRtreatment of domestic wastewater will be implemented

1. Can anaerobic treatment performance be improved, especially at low temperatures?

2. Is AnMBR technology cost and environmentally advantageous to conventional treatment technologies?

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• Three submerged flat‐sheet membranes 

• Biogas sparging for fouling control, independently controlled for each membrane

• Psychrophilic temperature (15oC)

• Inoculated with mesophilic sludge only

1,000 cm2

P1 P2 P3

Bench‐scale AnMBR study to evaluate question 1

Smith, A.L., S.J. Skerlos, and L. Raskin, 2015. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment. 

Microbial Biotechnology, 8, 883‐894.

1. Can anaerobic treatment performance be improved, especially at low temperatures?

0

100

200

300

400

500

600

700

152 172 192 212 232 252 272 292

COD (mg/L)

Days from Startup

Influent

15°c12°c

9°c6°c

3°c

Excellent AnMBR performance maintained down to 6°C

Permeate

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0

100

200

300

400

500

600

700

152 172 192 212 232 252 272 292

COD (mg/L)

Days from Startup

Influent

Bioreactor

15°c12°c

9°c6°c

3°c

Biofilm’s role in treatment becomes more critical as temperature decreases

Permeate

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

100 105 110 115 120 125 130 135

Methan

e Oversaturation

Days from Startup

1.1 ± 0.22

1.7 ± 0.44

2.6 ± 0.30High Fouling

Low Fouling

Medium Fouling

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

100 105 110 115 120 125 130 135

Methan

e Oversaturation

Days from Startup

1.1 ± 0.22Low Fouling

However, dissolved methane increasingly a problem with thicker biofilms

Methane oversaturation = Dissolved methane measured in permeate / calculated equilibrium concentration

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Must answer important questions before AnMBRtreatment of domestic wastewater will be implemented

1. Can anaerobic treatment performance be improved, especially at low temperatures? Yes: biofilms improve performance but cause unwanted dissolved methane oversaturation in the permeate

2. Is AnMBR technology cost and environmentally advantageous to conventional treatment technologies?

Must answer important questions before AnMBRtreatment of domestic wastewater will be implemented

1. Can anaerobic treatment performance be improved, especially at low temperatures? Yes: biofilms improve performance but cause unwanted dissolved methane oversaturation in the permeate

2. Is AnMBR technology cost and environmentally advantageous to conventional treatment technologies?

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AnMBR has greater net energy demand and global warming impact than competing technologies

Smith AL, Stadler LB, Cao L, Love NG, Raskin L, Skerlos SJ, 2014, ES&T. 48(10):5972-81.

AnMBR today:• Membrane sparging contributes 

most to energy demand• Dissolved methane in permeate 

contributes to 75% of global warming impact

Future AnMBR design requires:• Reduction in methane 

oversaturation• Dissolved methane recovery• Reduction in energy for fouling 

mitigation

Are AnMBRs for recovery of energy from domestic wastewater a sustainable technology?

• Does the design make significant progress toward an unmet and important environmental or social challenge? 

• No: the world has plenty of energy and global warming potential not addressed.  More work to do.

• Is there potential for the design to lead to undesirable consequences in its lifecycle that overshadow the environmental/social benefits? 

• Yes: Excess greenhouse gas (GHG) emissions

• Is the design likely to be adopted and self‐sustaining in the market? 

• The value proposition right now is mainly smaller size.  Net zero energy is possible after more research.  The GHG issue is of industry concern and will be a show‐stopper for now.

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New Question

How do we address drawbacks of conventional AnMBRs so that they are cost and environmentally advantageous to existing technologies?

Dynamic Membrane: Filtering biofilm formed on support structure of ~ 10 – 100 microns

• Membrane cleaning is energy intensive (High OPEX)• Less Pore Blocking • Lower Transmembrane Pressures

• Membrane material cost is expensive (High CAPEX)• Cheaper Material (e.g. nylon, polyester, stainless steel mesh)• Higher Fluxes – less membrane area required

Must address further hurdles of AnMBRs with novel design decisions

• Harness Maximum Biofilm Treatment

Modify bioreactor design and operating conditions to improve outcomes

• Reduce Dissolved Methane Saturation to Equilibrium in Permeate

• Maintain Effective Solids/Liquid Separation with Lower Energy Demand and Cost

Create large surface area for biofilm formation

Force wastewater through biofilm many times

Utilize conductive surface to promote DIET

Shift methane production away from biofilms on permeating membranes

Incorporate flow pattern that allows for efficient transfer of dCH4 to gas headspace

Utilize fine meshes instead of MF/UF membranes which allow for low transmembrane pressure

Mesh material (e.g. nylon, polyester, stainless steel) lower capital cost than typical MF/UF membrane

Operate at much higher flux than MF/UF, so less membrane area required 

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Develop dynamic membrane biofilm on mesh around branches in contact with influent

Permeate

• maintain effective solids/liquids separation with lower energy demand?

Utilize fine meshes instead of MF/UF membranes

Recirculation

• harness maximum biofilm treatment?

Force wastewater through biofilm many times

• reduce dissolved methane oversaturation in permeate?

Shift methane production away from biofilms on permeating membranes and allow for dissolved gas transfer to headspace

Influent

Develop dynamic membrane biofilm on mesh around branches through which permeate leaves

Novel dynamic membrane bioreactor (DMBR) solves longstanding hurdles for conventional MBR treatment of domestic wastewater

MagnaTree Flow pattern through meshes to develop dynamic membrane achieves desired outcomes

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MagnaTree implementation in a bioreactor analogous to integrated fixed film activated sludge (IFAS) system 

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120

% Total‐COD Removal

Days Since Startup

Startup results promising: tCOD removal increased to ~ 90% & large portion (~62%) of tCOD transformed to biogas methane. 

18%

62%

4%14%

2%

Partitioning of Total Influent COD

% COD in dCH4

% COD in gCH4

% COD for sulfate reduction

% COD for biomass growth

% unknown

T: 22 – 23° C

• At 15° C, %COD in dCH4 found to be  ~31% of total COD

Smith, A.L., S.J. Skerlos, and L. Raskin, 2015. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment. Microbial Biotechnology, 8(5):883‐894.

Effluent COD: 53 – 59 mg/L

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Methane saturation quickly fell to 1 (equilibrium)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100 120

Degree of CH4 saturation

Days Since Startup

Reactor

Permeate

Reactor: 0.99 ± 0.07

Permeate: 0.97 ± 0.07 

Methane Saturation after day 12

AnMBR Treatment of DWW at Ambient (often low) Temperatures – Early Observations

• Can anaerobic systems adequately treat domestic wastewater, even at low temperatures?• Yes, An(D)MBRs can achieve sufficient COD and SS removal while also producing biogas

• Where might we apply novel (An)DMBR (e.g. MagnaTree) technology?• Retrofit for existing municipal plants – expand capacity/improve performance

• Decentralized wastewater treatment, especially in developing countries

• Industrial applications such as food and beverage wastewater

• Part of reuse treatment train – reduce fouling to RO/UF membranes

• How do conventional AnMBRs compare to novel AnDMBRs?

• High energy demand• High global warming impact• High capital cost• Complete solids removal

• Low energy demand• Low global warming impact• Low capital cost• High solids removal

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Acknowledgements

Freddy OrdonezEnvironmental Eng. 

Graduate Student, UM

Ilse SmetsProfessorKU Leuven

Nancy LoveProfessor

UM

Charles BottDirector of Water 

Technology and ResearchHRSD

Juliana HuizengaEnvironmental Eng. 

Undergraduate Student, UM

Nigel BeatonEnvironmental Eng. 

(Previous)Graduate Student, UM

Questions for Our Speakers?

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Thank You

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