Microbial Fuel Cell Technologies‐‐ - Department of Energyenergy.gov/sites/prod/files/2015/04/f21/fcto_beto_2015_wastewaters... · Microbial Fuel Cell Technologies‐‐ MxCs:

Microbial Fuel Cell Technologies‐‐MxCs Can they scale

(Yes) Bruce E Logan

Penn State University

Engineering Energy amp Environmental Institute

MFCs

Anode

Fuel (wastes)

Oxidation products

(CO2)

Bacteria that make electrical current

Electrical power generation in a Microbial Fuel Cell (MFC) using exoelectrogenic microorganisms

load e - e - Cathode

Oxidant (O2)

Reduced oxidant (H2O)

Liu e t al (2004) Environ Sci Technol

H+

2

3

Scaling up MFCs amp MECs MFCs= fuel cells make electricity MECs= electrolysis cells make H2

3

4

MEC Reactor that has 24 modules with a total of 144 electrode pairs (1000 L)

Cusick et al (2011) Appl Microbiol Biotechnol 4

5

Individual module performance of the MEC treating Wastewater

Predicted 380 mAmodule (total of 92 A)

500

Mod

ular

Cur

rent

(mA)

400

300

200

100

0 1 3 5 7 9 11 13 15 17 19 21 23

Module Number

H2 initially produced but it all was converted to CH4

Elec Energy input= 6 Wm3

Energy Out = 99 Wm3

16times more energy recovered than electrical energy put into the process

Cusick et al (2011) Appl Microbiol Biotechnol 5

MFC Architecture Estimates for MFCs bull 100 euro m2 or $130m2

Estimates for MECs bull 100 euro m2 or $130m2

6

MFC Architecture

Anode Cathode

Wastewater AIR

Diffusion Separator Layer (DL)

Carbon Cloth

Catalyst (Pt) Binder (Nafion)

Original systems $m2 (US) bull Carbon cloth~ $1000

bull Pt catalyst~ $ 500

bull Binder~ $ 700

bull DL (PTFE)~ $ 030

bull Separator~ $ 1

TOTAL $2200

New systems $m2 (US) bull Anode $20

bull Cathode $15 ‐ SS + CB= $20

‐ Catalyst (AC)=$040

‐ Binder= $15

‐ DL (PDMS)= $015

bull Separator $ 1

TOTAL $36

7

8

MFC Materials Anode Graphite brush electrode bull Graphite fibers commercially

available (used in tennis rackets airplanesetc)

bull Easy to manufacture

bull Fiber diameter‐ 6‐10 μm a good match to bacteria (~1 μm)

bull High surface area per volume‐Up to 15000 m2m3

Logan et al (2007) Environ Sci Technol 8

Voltage Production Results Brushes still work better than flat mesh

B= Brush anode M= Mesh (flat) anode

Hays and Logan (2011) J Power Sources 9

Multi‐electrode MFCs

3 brushes (R3) 5 brushes (R5) 8 brushes (R8) 3500 m2m3 2800 m2m3 2900 m2m3

Electrode area (25 cm diameter brushchamber width = 40 m2m3

Lanas amp Logan (2013) J Power Sources 10

Cathode Activated Carbon Catalysts Carbon cloth with Pt

VITO cathode (no Pt)

Activated carbon cathode works almost as well as Pt catalyst

0

500

1000

1500 P

ower

Den

sity

(mW

m2 )

VITO cathode- with Pt

VITO cathode (no Pt)

0 2 4 6 8 10 Current Density (Am2)

11Zhang Cheng Van Bogaert Pant amp Logan (2009) Electrochem Commun

0

200

400

600

800

1000

1200

1400

1600

Max

imum

Pow

er D

ensi

ty (m

Wm

2 )

0

200

400

600

800

1000

1200

1400

1600

Pow

er D

ensi

ty (m

Wm

2 )

Activated Carbon Cathodes‐ (Manufactured by VITO)

0

200

400

600

800

1000

1200

1400

1600 Po

wer

Den

sity

(mW

m2 )

AC AC-Fe AC-Heat AC-CB Pt

B - 16 months A - 1 month

0 2 4 6 8 10 0 2 4 6 8 10 Current Density (Am2) Current Density (Am2)

0 5 10 15 20 Time (months)

0

200

400

600

800

1000

1200

1400

1600

0 2 4 6 8 10

Pow

er D

ensi

ty (m

Wm

2 )

Current Density (Am2)

DC - 17 months-HCl DI Water rinse HCl

Performance over 16 months

Original powernearly restoredusing acid (HCl)wash

Zhang Pant Zhang Liu Logan (2014) Chem Electro Chem 12

13

New Binder for Activated Carbon PVDF bull Using a PVDF binder is simple and effective

ndash 1‐ apply to SS mesh 2‐ phase inversion in water ndash Make at room temperature

ndash Amenable to continuous rolling process ndash No separate gas diffusion layer (GDL) needed

ndash Cost $15 mndash2 ($12 mndash2 for SS mesh $3 mndash2 for catalyst and binder)

Yang He Zhang Hickner Logan (2014) ESampT Letters

PVDF Binder Power the same as PTFE

bull Water pressure up applied to carbon clothPt to 12 m (vs 02 m for PTFE)

Yang He Zhang Hickner Logan (2014) ESampT Letters

Acetate amp PBS buffer

New-rev

Domestic Wastewater

14

MFCs and MECs for Wastewater Treatment

hellipand why MxCs alone cannot accomplish wastewater treatment

Low sCOD limits current generation

900

0

1

2

3

4

0 10 20 30 40 50 60 C

urre

nt D

ensi

ty (A

m2 )

Ac High 100 Ω Current

Ac High 100 Ω COD

D

ACETATE Current very stable then it suddenly decreases

800

700

CO

D (m

gL)

600

500

400

300

COD removal constant (first-order kinetics) 100

200 sCOD ~ 180 mgL

0

Time (h)2 500

450WW 100 Ω Current WW 100 Ω sCOD WW 100 Ω tCOD

WW

0 5 10 15 20 25 30

In both cases COD continues to be removed so treatment continues without electricity generation but ww cannot be discharged due to high COD

16

12

400

Cur

rent

Den

sity

(Am

2 )

CO

D (m

gL)350

300 250

tCOD ~ 150 mgL

sCOD ~ 100 mgL

08 200 150

04 100 50

0 0

Time (h)

Zhang He Ren Evans Logan (2015) Biores Technol 16

1

Current density vs soluble COD (sCOD) Current rapidly drops off at ~100 mgL sCOD

4

Ac Low 1000 Ω

Ac High 1000 Ω

WW 1000 Ω Cur

rent

Den

sity

(Am

2 )

1000 Ω

0 200 400 600 800 1000

Ac Low 100 Ω

Ac High 100 Ω

WW 100 Ω

WW-R 100 Ω

100 Ω

0 200 400 600 800 1000

Cur

rent

Den

sity

(Am

2 ) 08

06

04

02

0

3

2

1

0

COD (mgL) COD (mgL)

In both cases current rapidly decreases when sCOD is still high (~100 mgL)

17Zhang He Ren Evans Logan (2015) Biores Technol

How much COD removal can we get from domestic WW ~80‐90 but final COD is too high

Hays and Logan (2011) J Power Sources

‐Why isnrsquot more COD removed ‐What is ldquofaterdquo of COD

bull Influent

COD = 400 mgL or BOD5 = 200 mgL

bull Effluent BOD5 35‐40 mgL (like a Trickling Filter)

Removal gt80

18

MFC Performance using Domestic Wastewater

Wastewater and Design Considerations

bull Acetate + Phosphate buffer ne SyntheƟc wastewater ndash Acetate concentrations are usually too high to represent WW

ndash PBS used is artificially conductive7‐20 mScm (vs 1 mScm for WW)

bull Domestic wastewater ndash COD of ~300‐500 mgL (50 BOD5) ndash Composition is variable So lots of oxygen contamination of the

anode over time can have anode limitations on performance

bull Reactor design ndash Canrsquot have too narrow space between electrodes (it will clog) ndash Must take into account volume demands of air cathodes

bull Final effluent quality ndash If domestic ww used + need to discharge = Need AFMBR

ndash If industrial may only need to get to level suitable for discharge to sewers (no secondary process needed in this case)

MFC Architecture

Logan amp Elimelech (2012) Nature 21

22

Overall goal compact reactor design

Assume One anode-cathode module is 1 m2 projected area (height x width) and 10 cm thick

Result 10 modules = 10 m2

10 cm

10 cm

10 cm

10 cm

Design Limited by cathode area so in this example we achieve 10 m2m3

10 cm 100 cm

Logan (2012) Chem Sus Chem 22

MFC + AFMBR (Anaerobic Fluidized Bed Membrane Bioreactor)

Ren Ahn amp Logan (2014) Environ Sci Technol 23

Generation I MFC configuration

bull SEA Separator electrode assembly ndash Trimmed graphite fiber brush one side flat ndash Separator between brush anode and

cathode placed together

bull SPA Spaced electrode assembly ndash Brush placed distant from cathode so it

canrsquot touch it

bull Two reactors used in series ndash 2 times 4 h HRT = 8 h HRT

bull Total of 4 MFCs (2 SEA 2 SPA)

Ren Ahn amp Logan (2014) Environ Sci Technol 24

AFMBR Construction bull Idea of AFMBR first published by

Chae et al (ESampT) Used as a second stage to granular fluidized bed anerobic digester

bull AFMBR consists of a reactor body + ultrafiltration membrane + granular activated carbon (GAC)

bull GAC fluidized by recirculation

bull In tests here used with a hydraulic retention time of 1 hour

Ren Ahn amp Logan (2014) Environ Sci Technol 25

Experimental Setup MFC+AFMBR

Reactor HRTs MFC=4 h (each) AFMBR=1 h ldquoFrdquo= Granular activated carbon (GAC) fluidized used for

biofilm support and membrane cleaning (scour) ldquoMBRrdquo PVDF hollow fiber membranes MFC types SEA (separator) SPA (spaced no separator)

26Ren Ahn amp Logan (2014) Environ Sci Technol

Comparison of performance of SEA and SPA MFCs over time

bull Initially similar performance

bull After 5 months SEAgtgt SPA

bull Separator needed for long term performance

01

02

03

Pow

er (m

W)

SPA-U SEA-U SPA-D SEA-D

a

01

02

03

Pow

er (m

W)

NEW

05 1 15 2 Current (mA) U= Upflow (1st MFC in series)

0404

0 0

b After 5 months

0 05 1 15 2 Current (mA)

D=downflow (2nd MFC in series)

Ren Ahn amp Logan (2014) Environ Sci Technol 27

Effluent reduced to 16 mgL tCOD 250

bull Two trains of MFC (HRT = 4 h) to AFMBR (HRT = 1 h)

bull Membrane flux 16 Lm2h

bull 50 days performance

bull Energy balanced

(MFC produced = AFMBR used)

Con

cent

ratio

n (m

gL)

200

150

100

50

0 tCOD sCOD TSS

MFCs FMBR Effluent

491

503

510 434

359 486

925

862

996

bull Effluent COD = 16 mgL bull Effluent TSS lt1 mgL

WW in FMBR Permeate Ren Ahn amp Logan (2014) Environ Sci Technol 28

Key to AFMBR success Little fouling bull First 10 days initial rapid

increase in transmembrane 01 pressure (TMP)

bull Days 10‐50 only slight increase 008

in TMP

bull Flux of 16 LMH much greater than that in previous studies with anaerobic fluidized bed

TMP

(bar

)

006

004

002

0 10 20 30 40 50

reactors (AFBRs) ndash AFMBR 6‐7 LMH at start 0 ndash 4‐11 LMH at start

Time (d)

Ren Ahn amp Logan (2014) Environ Sci Technol 29

30

Conclusions

bull Microbial Fuel Cell Technologies‐‐MxCs Can they scale

Yes

30

MET Companies bull Emefcy (Israel) wwwemefcycom bull Cambrian Innovations (Boston MA) httpcambrianinnovationcom

bull ArbSource (with Arizona State University) wwwarbsourceus bull Waste2Watergy (with Oregon State University)

advantageoregonstateeduclientswaste2watergy

bull Living Power (with Harvard University) bull Quantum Intelligence (San Jose CA) bull Electroarchae wwwelectroarchaecom

bull MicroOrganic (New York) httpmicrorganictechcomtechnology bull

Thanks to students and researchers in the MxC team at Penn State

Current research sponsors SERDPDOD (2012-2015) Air ProductsDOE (2012-2014) GCEPStanford (2012-2015) NRELDOE (2012-2014)

International Collaborations