Life Cycle Assessment and Cost Analysis of Membrane Bioreactor Systems:Influence of Scale, Population Density, Climate, and Methane Recovery

Office of Research and DevelopmentNational Exposure Research LaboratoryNational Risk Management Research Laboratory

3/27/18

Sarah Cashman, Eastern Research Group, Inc.Cissy (Xin) Ma, U.S. EPAJanet Mosley, Eastern Research Group, Inc.Brian Crone, University of CincinnatiXiaobo Xue, State University of New York at AlbanyJay Garland, U.S. EPABen Morelli, Eastern Research Group, Inc.

The Challenge

• Aging infrastructure and costs associated with upgrading or expanding of centralized treatment systems and distribution systems

• Water scarcity and challenges in meeting water system demands

• Meeting green building and net-zero development goals

1

FINDING NEW WATER Alternative Water Reuse

RAINWATER(ROOFRUNOFF)

GRAYWATER(SHOWER, SINK,

LAUNDRY)

BLACKWATER(TOLIET

WASTEWATER)

STORMWATER(LAWN &

SURFACE RUNOFF)

TREATMENT

Aerobic Membrane Bioreactor (MBR)

Mesophilic Anaerobic MBR (AnMBR)

Psychrophilic AnMBR

NON POTABLE USE

Energy, Greenhouse Gas (GHG) & Cost Analysis of MBRs

• Understand environmental and cost impacts of transitional decentralized MBR systems with sewer mining

• Investigate life cycle assessment (LCA) and life cycle cost (LCC) performance of MBRs under various regional and technological parameters

3

General Decentralized Treatment System Boundaries• Boundaries start at household

wastewater collection• End at downstream use of

recycled watero Recycled water displaces

production of potable water• MBR treatment systems

transitional, use existing infrastructure for sludge processes

• For AnMBR, CH4 from headspace and is recovered converted to electricity/heat

Wastewater Collection

Pretreatment

MBR Operation

Disinfection

Recycled Water Delivery

Solids to Centralized Treatment

Displaced Potable Water

4

MBR Operation

Plug Flow Activated

Sludge Diffused Aeration

Purchased Electricity AeMBRScouring

Permeate Pumping

AeMBR Subprocesses

Influent Heating

AnMBR Electrical Microturbine

Natural Gas

Purchased Electricity

Permeate Pumping

Heat Exchanger

Biogas Recirculation

Pump

Methane

Electricity

Heat LossControl

Heat

AnMBR Subprocesses

Electricity

5

Scale and Land Use Scenarios

6

Land Use Type

0.05MGD (500 ppl served)

0.1MGD(1,000 ppl served)

1MGD(10,000 ppl

served)

5MGD(50,000 ppl

served)

10MGD(100,000

ppl served)100,000 #ppl/sqm

High density urban

0.005 sqm 0.01 sqm 0.1 sqm 0.5 sqm 1 sqm

50,000 #ppl/sqm Multi family 0.01 sqm 0.02 sqm 0.2 sqm 1 sqm 2 sqm

10,000 #ppl/sqm Single

family 0.05 sqm 0.1 sqm 1 sqm 5 sqm 10 sqm

2,000 #ppl/sqm

Semi-rural single family

0.25 sqm 0.5 sqm 5 sqm N/A N/A

-Scenarios applied to AeMBR, mesophilic AnMBR (35˚ C), psychrophilic AnMBR (Ambient). -Average U.S. weather conditions (21.5˚ C).-Note: ppl = people

Psychrophilic AnMBR Scenarios

7

Influent Temperature = 17.9˚ C

Cold Climate (6˚ C)

Reactor Insulation:-Included-Excluded

Methane Recovery Options-With and without methane permeate recovery-Recovery options: flare, CHP, conversion to elect. only

Warm Climate (26.4˚ C)

1 MGD Scale

Psychrophilic AnMBR

Multi Family Land Use

Influent Temperature = 26.4˚ C

Methods and Data Sources• MBR technology modeled using flux, cleaning, and module

specifications for GE ZeeWeed® 500D hollow-fiber membrane with LEAPmbr aeration

• CAPDETWorks™ software used to develop life cycle inventory for preliminary treatment, fine screening, AeMBR operation and infrastructure, AnMBR infrastructure, and disinfection with chlorine

• Energy modeling for AnMBR process derived from Feickert et al., 2012

• Quantity of methane dissolved in permeate and energy use for dissolved methane recovery based on engineering calculations

• Recycled water delivery based on engineering calculations for pumping friction losses and infrastructure

• Completed full LCA using openLCA software8

Influence of Population Density and Scale on Global Warming Potential (GWP)

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

AeM

BR

AnM

BR, 3

5 ˚C

AnM

BR, 2

0 ˚C

AeM

BR

AnM

BR, 3

5 ˚C

AnM

BR, 2

0 ˚C

AeM

BR

AnM

BR, 3

5 ˚C

AnM

BR, 2

0 ˚C

AeM

BR

AnM

BR, 3

5 ˚C

AnM

BR, 2

0 ˚C

AeM

BR

AnM

BR, 3

5 ˚C

AnM

BR, 2

0 ˚C

0.05 MGD 0.1 MGD 1 MGD 5 MGD 10 MGD

kg C

O2

eq./

m3

was

tew

ater

trea

ted

semi rural single family single family multi family high density urbanLand Use Type

9 Same General Trends for Cumulative Energy Demand

Influence of Methane Recovery Options on GWP

10

biogas flare, nopermeatemethanerecovery

biogas flare,permeatemethanerecovery

conversion toelectricity, no

permeatemethanerecovery

conversion toelectricity,permeatemethanerecovery

CHP, nopermeatemethanerecovery

CHP, permeatemethanerecovery

kg C

O2

eq/m

3w

aste

wat

er tr

eate

d

Collection system and primary treatment

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

Heating of influentHeat loss control Recovery of methane from headspaceMBR operation (electrical demand, chemicals, infrastructure) ChlorinationRecovery of methane from permeate Methane emissions from permeateRecycled water delivery Displaced drinking waterNet total

Base scenario assumes cold climate and reactor insulation.

11

Influence of Reactor Scale

Global Warming Potential Cumulative Energy Demand

-0.60-0.40-0.200.000.200.400.600.801.00

0.05 0.1 1 5 10

Reactor Scale (MGD)

kg C

O2

eq/m

3 w

aste

wat

er tr

eate

d

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

0.05 0.1 1 5 10

Reactor Scale (MGD)

MJ/

m3

was

tew

ater

trea

ted

AeMBR AnMBR (mesophilic) AnMBR (psychrophilic)

Effect of MBR Improvements Strategies on GWP under Different Climate Conditions

12

-1.00

-0.80

-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0.80

Base* Add Insulation Shift Flare Biogasfrom Headspace to

Conversion toElectricity

Add PermeateMethane Recovery

Shift Conversion ofHeadspace/Permeate

Methane fromElectricity Only to

CHP

kg C

O2

eq/m

3 w

aste

wat

er tr

eate

d

Cold Climate (Ambient Temperature = 6˚ C) Warm Climate (Ambient Temperature = 26.4˚ C)

Net GWP burdens

Net GWP benefits

*Base = no reactor insulation, biogas flare only, no permeate methane recovery

13

$7.48

$4.32

$1.11 $0.68 $0.58

$9.10

$5.63

$2.27$1.67

$1.54

$8.89

$5.49

$2.14$1.54$1.41

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

0.05MGD

0.1MGD

1MGD

5MGD

10MGD

0.05MGD

0.1MGD

1MGD

5MGD

10MGD

0.05MGD

0.1MGD

1 MGD5 MGD 10MGD

AeMBR Mesophilic AnMBR Psychrophilic AnMBR

$/m

3 W

aste

wat

er T

reat

ed

Amortized Capital Cost O&M Costs Energy Cost Avoided DWT Cost Net Total

Comparative MBR Costs ($/m3

Wastewater Treated)

Applicable for multi-family land use scenario

Influence of Parameters on Study Outcome

14

80%

60%

40%

20%

0%

Reactor Scale100%

PopulationDensity

Climate

Electrical Grid

kWh forDisplacedDrinkingWater

ReactorTemperature

MethanePermeateRecovery

MethaneRecovery

Option

ReactorInsulation

GWP variation fromparameter range (%of maximum kg CO2eq. range per m3wastewater treated)

Energy demandvariation fromparameter range (%of maximum MJrange per m3wastewater treated)

Cost variation fromparameter range (%of maximum $ rangeper m3 wastewatertreated)

FINDING NEW WATER – Urban Case Study

RAINWATER(ROOFRUNOFF)

GRAYWATER(SHOWER, SINK,

LAUNDRY)

BLACKWATER(TOLIET

WASTEWATER)

STORMWATER(LAWN &

SURFACE RUNOFF)

TREATMENT

NON POTABLE USE

Aerobic MBR

Psychrophilic Anaerobic MBR

MBR with Thermal Recovery

Recirculating Vertical Flow Wetland

Urban Case Study Scenarios

16

Mixed WastewaterSeparated Graywater

Larg

e M

ixed

Use

(O

ffice

/Res

iden

tial)

Dis

trict

-Sew

ered

Dis

trict

-Uns

ewer

ed

Larg

e M

ixed

Use

(O

ffice

/Res

iden

tial)

Dis

trict

-Sew

ered

Total Flow Rate0.025 MGD 0.05 MGD

Flow Rate of Water Treated

0.016 MGD 0.025 MGD 0.031 MGD 0.05 MGD

People Served 1,100 2,249 1,100 2,249 1,100

Building Footprint (Roof Area) 20,000 155,969 20,000 155,969 20,000

Area Served (sq. ft) 380,000 754,981 380,000 754,981 380,000

AeMBR System Boundaries

17

Key

End Use

Influent Mixed

Wastewater

Influent Graywater

Fine Screening and Grit Removal

Aerobic Membrane Bioreactor

Screening and Grit to Landfill Sludge to Municipal

Wastewater Treatment

ChlorinationUV

Disinfection

Recycled Water

Pumping

Irrigation

Showers and Baths

Dishwasher and Kitchen

Sink

Graywater Collection Gravity System

Wastewater Collection Gravity System

StorageToilet Flushing

Bathroom Sinks

Laundry

Displaced Potable Water Treatment and Delivery

Or gate (multiple inputs)

Or gate (multiple outputs)

Unit process within system

boundary

Unit process outside system

boundary

Displaced unit process

Demanded Drinking Water Treatment and

Delivery

Dewateringa

Sludge Transporta

Windrow Compostinga

Notesa Unsewered scenario only considered for district-level analysis treating mixed wastewater.

Flow within system boundaries

Flow outside system boundaries

Displaced product flow

Displaced Fertilizer

Productiona

Land Application of Composta

Water from dewatering stepa

Conclusions and Next Steps• MBR LCA and cost impacts decrease as the scale increases due to economies of scales, scale strongly influences overall impacts esp. cost

• All assessed impacts decrease in both AeMBR and AnMBR as population density increases, but population density does not drive results

• In warmer climate, AnMBR results in notable energy and GHG benefits compared to the AeMBR

• Significant energy, GHG benefits from displaced drinking water and energy recovery (in case of AnMBR)

• Communities can adapt LCA/LCC model framework for specific technological and regional conditions

18

Acknowledgements and DisclaimerThis research was part of the U.S. Environmental Protection Agency (U.S. EPA) Office of Research and Development’s Safe and Sustainable Water Resources (SSWR) Program. The research was supported by U.S. EPA contracts to EP-C-12-021 and EP-C-16-0015 to Eastern Research Group, Inc. Although the information in this document has been funded by the U.S. EPA, it does not necessarily reflect the views of the Agency and no official endorsement should be inferred.

19

Contact Information

20

Xin (Cissy) Ma Ph.D, P.E.Ma.cissy@epa.gov

513-569-7828

Sarah Cashmansarah.cashman@erg.com

781-674-7233

5

ADDITIONAL SLIDES

5

LCA database development

Range of Displaced Potable Water Energy Demand Reported in Literature

00.10.20.30.40.50.60.70.80.9

Raw Water Pumping,Surface Plant/Treatment

(n=13)

Finished Water Pumping (n= 10)

Total Drinking WaterTreatment and Supply (n =

14)

kWh/

cubi

c m

eter

drin

king

w

ater

From: Cashman S., Mosley J., Ma C., Garland J., Cashdollar J., and Bless D. Life Cycle Assessment and Cost Analysis of Water and Wastewater Treatment Options for Sustainability: Influence of Scale on Membrane Bioreactor Systems. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-16/243, 2016.

Regionalized Electrical Grid ProfileFuel mix of electrical grid affects magnitude of environmental burdens for both the MBR life cycle and the displaced potable water

0200400600800

100012001400160018002000

RFCE CAMX FRCC AZNM ERCT RFCW

Crad

le -

to -

Gene

ratio

n Em

issio

nsCO

2 eq

(lb/

MW

h)

U.S. Average

Source: U.S. EPA eGRID 2012

Influence of Electrical Grid and Displaced Water Assumptions on GWP

kg C

O2

eq/m

3 w

aste

wat

er tr

eate

d

-0.60-0.40-0.200.000.200.400.600.801.00

1 MGD AeMBR AnMBR(mesophilic)

AnMBR(psychrophilic)

1 MGD AeMBR AnMBR(mesophilic)

AnMBR(psychrophilic)

U.S. Average Electrical Grid RFCW eGRID Sub Region

Minimum Electricity Displaced Drinking WaterMedian Electricity Displaced Drinking WaterMaximum Electricity Displaced Drinking Water

Effect of MBR Improvements Strategies on Energy Demand under Different Climate Conditions

-18.0-16.0-14.0-12.0-10.0

-8.0-6.0-4.0-2.00.02.04.0

MJ/

m3

was

tew

ater

trea

ted

Cold Climate (Ambient Temperature = 6˚ C)

Net CED burdens

Net CED benefits

Base* Add Insulation Shift Flare Biogas fromHeadspace toConversion to

Electricity

Add Permeate MethaneRecovery

Shift Conversion ofHeadspace/Permeate

Methane fromElectricity Only to CHP

Warm Climate (Ambient Temperature = 26.4˚ C)

*Base = no reactor insulation, biogas flare only, no permeate methane