New energy conversions using

microorganisms and electrodes

Annemiek ter Heijne

Sub-department of Environmental Technology

Sep 24, 2015

Wastewater contains energy!

From aerobic to anaerobic wastewater

treatment

Source: http://www.uasb.org

Since 1970/80’s Before 1970/80’s

COD = chemical oxygen demand = measure for organic components in wastewater

A next generation wastewater treatment is

required

Biogas Production

Biogas Treatment (a.o. H2S removal)

Electricity Production (gasmotor)

Electricity

Source: http://www.paques.nl

Efficiency: +/- 30%

# of Units: At least 3

Electrochemically active microorganisms

Microorganisms catalyze the oxidation of

wastewater (acetate) at the bio-anode

CH3COOH + 2 H2O 2 CO2 + 8 H+ + 8 e-

Microbial Fuel Cells convert wastewater

directly into electricity

acetate

CO2

waterbacteria

anode cathode

oxygen

H+

electrons

acetate

CO2

waterbacteria

anode cathode

oxygen

H+

electrons

Cell configurations for bioelectrochemical

systems

Versatility in reactions and applications

MFC

MEC

Microbial Electrolysis Cells for hydrogen

production from wastewater

We need a breakthrough...

Year

... and we need experience with scaling-up

Decreasing internal resistance

Decreasing material cost

Increasing revenues (niche applications)

Capacitive electrodes for bio-anodes

Improved performance with a capacitive

layer

Deeke et al., 2012, ES&T

Capacitive bio-anode

Non-capacitive bio-anode

Acetate CO2 + H+

e-

e-

e-

e-

e- e-

e- e-

K+

K+

NH4+

K+

H+

NH4+ K+

Na+

e-

e- e-

e-

e-

e-

e-

e- e-

e-

e-

e- e-

K+

K+

K+

K+

K+ K+

NH4+

NH4+

H+

H+ H+

H+

H+

Na+ NH4

+

NH4+ e-

NH4+

H+

K+

e- Acetate

CO2 + H+

Acetate

CO2 + H+

Capacitive granules (activated carbon)

500 m2/g

Electro-active biofilm

Activated carbon granules as a basis for a

fluidized bed Microbial Fuel Cell

e-

N2 gas

wastewater

clean water

H+ Charging reactor

Discharge cell

anode

cathode

O2 + H+

H2O

Capacitive Fluidized Bio-anode

Increase in current density with increasing

granule loading: proof of principle

Time (days)

80 100 120 140 160 180 200 220 240

Curr

ent de

nsity (

A/m

2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

100 g AC

150 g AC

200 g AC

Deeke et al., 2015, ES&T

Measure single granule behaviour under

controlled conditions

1.5 cm

One single granule can produce 0.6 mA:

>1,000x more than achieved in reactor

Understand fundamentals: Capacitance of

electrode influenced by biofilm

GAC PK GG

CV

(F

cm

-3)

0

20

40

60

80

Biotic

Abiotic

GG

0.0

0.5

1.0

1.5

A

Non-capacitive Capacitive

Develop a reactor that can achieve higher

conversion rates (current)

Nitrogen and energy recovery from urine:

high soluble COD and NH4+ concentrations

Value from Urine principle

NH3 recovery BES

Struvite

recovery

Collection

Microorganisms catalyze N and energy

recovery from urine

Acclimation of bio-anodes to urine

Piloting urine treatment (30 persons) at

Wetterskip Fryslan & Wetsus

Proof of principle: copper and electricity

recovery

Ter Heijne et al. ES&T, 2012

Cell configuration with low internal

resistance

Rodenas Motos et al., Front.inMicrobiol., 2015

High-rate microbial fuel cell with copper

Plant Microbial Fuel Cell

New source

24 h/d

Self repairing

No fine dust emissions

Proof-of-principle: plants produce electricity

Strik et al. 2008 Int. Journal Energy Research 32

Power to (bio-)gas

www.electrochaea.com

Biocathodes offer an energy efficient

alternative for power to gas

Methane production rate (m3/m3 per day)

𝜂Coulombic(%) methane

PhaseI 0.2119 59.49

Phase II 0.2875 56.23

Phase III 0.2454 58.31

Phase IV 0.2604 55.35

Continuous and stable methane production

Electricity storage as chemical energy

Acetate production at biocathodes as

alternative to methane

Jourdin et al., J.Mater.Chem.A ,2014

Biobattery for storage of electricity in the

form of acetate: proof of principle

Anode

Cathode

A-

C+

Ac-

O2

H2O

+

+

CO2

Biobattery perspective depends on maximum

acetate concentration

0

50

100

150

200

250

0 0,5 1 1,5 2

Energ

y d

ensity (

Wh/L

)

Acetate concentration (M)

lead-acid battery

(old) li-ion battery

Proof-of-principle

Microorganisms and electrodes offer new

exciting possibilities for energy conversions

Capacitive granules

Urine treatment

Biobattery

Plant MFC

Copper recovery

Thank you for

your attention

Annemiek.terHeijne@wur.nl