New energy conversions using microorganisms and electrodes

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
Before 1970/80’s
Since 1970/80’s
COD = chemical oxygen demand = measure for organic components
in wastewater
Source: http://www.uasb.org
A next generation wastewater treatment is
required
Biogas
Production
Biogas
Treatment
(a.o. H2S removal)
Electricity
Production
(gasmotor)
Electricity
Efficiency:
# of Units:
+/- 30%
At least 3
Source: http://www.paques.nl
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
electrons
CO2
oxygen
H+
acetate
bacteria
anode
water
cathode
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
Capacitive bio-anode
Non-capacitive
bio-anode
Deeke et al., 2012, ES&T
Activated carbon granules as a basis for a
fluidized bed Microbial Fuel Cell
CO2 + H+
Acetate
Na+
eH+
e-
H+
e-
Capacitive granules
(activated carbon)
500 m2/g
K+
eee- K+
K+ e-
NH4+
K+
K+
e
H+
NH4+
eAcetate
H+
K+ e-
NH4+
e-
NH4+
CO2 + H+
Na+
eK+
K+
ee-
Acetate
K+
e-
+
e- NH4
e- H+
K+ e
eNH4+
H+ ee- NH4+
eH+
K+
e
CO2 + H+
Electro-active
biofilm
Capacitive Fluidized Bio-anode
clean
water
e-
O2 + H+
Charging
reactor
H+
anode
H2O
cathode
Discharge
cell
N2 gas
waste
water
Increase in current density with increasing
granule loading: proof of principle
1.4
100 g AC
150 g AC
200 g AC
Current density (A/m2)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
80
100
120
140
160
180
200
220
240
Time (days)
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
80
A
Biotic
Abiotic
CV (F cm-3)
60
1.5
40
1.0
0.5
20
0.0
GG
0
GAC
Capacitive
PK
GG
Non-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
Collection
Struvite
recovery
BES
NH3 recovery
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
Continuous and stable methane production
Methane production rate
(m3/m3 per day)
𝜂 Coulombic(%)
methane
PhaseI
0.2119
59.49
Phase II
0.2875
56.23
Phase III
0.2454
58.31
Phase IV
0.2604
55.35
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
Ac-
CO2
O2
+
A
n
o
d
e
C+
A-
C
a
t
h
o
d
e
+
H2O
Biobattery perspective depends on maximum
acetate concentration
Energy density (Wh/L)
250
(old) li-ion
battery
200
150
100
lead-acid
battery
50
Proof-ofprinciple
0
0
0,5
1
1,5
Acetate concentration (M)
2
Microorganisms and electrodes offer new
exciting possibilities for energy conversions
Urine treatment
Capacitive granules
Plant MFC
Copper recovery
Biobattery
Thank you for
your attention
[email protected]