Environmental Engineering Reference
In-Depth Information
Table 1.2 Maximum current densities per anode area reported by various researchers in MFC
Reference
Reported
current (A/m
2
)
Main substrate
Inoculum
Fan et al. (2007)
[26]
13
Acetate
(1,300 mg
BOD/l)
Enriched culture from wastewater
Torres et al.
(2008) [25]
11.5
Acetate
(1,600 mg
BOD/l)
G. sulfurreducens-enriched mixed
culture from wastewater
Fan et al. (2007)
[37]
9.0
Acetate
(1,300 mg
BOD/l)
Enriched culture from wastewater
Liu et al. (2005)
[36]
5.5
Acetate
(780 mg
BOD/l)
Wastewater
Cheng et al.
(2006) [35]
5.0
Glucose
(530 mg
BOD/l)
Wastewater
Rozendal et al.
(2007) [24]
2.4
Acetate
(640 mg
BOD/l)
Mixed enriched culture
Ringeisen et al.
(2006) [38]
0.1
Lactate
(various
conc.)
Shewanella oneidensis DSP10
Bond and Lovley
(2002) [12]
1.1
Acetate
(320 mg
BOD/l)
Geobacter sulfurreducens PCA
concentration, which serves as a proton carrier, decreased. It is possible that
the maximum current density produced in manyMFC studies is limited by pH
inhibition and proton transport. Further studies are needed to fully integrate
biofilm proton transport into a mathematical model that can estimate its
effect on current density in MFCs.
1.2.2.2 Electrical Potential Limitation in the MFC Anode
In this section, we extend the model to consider the unique solid electron-
acceptor respiration employed by ARB in the biofilm. The ARB biofilm carries
out a novel form of respiration by transferring electrons to the anode, which is a
solid conductive electrode, not a soluble molecule, such as dissolved oxygen.
Although a solid, conductive electrode does not have a concentration, its
electrical potential serves as an analog for calculating reaction kinetics. By
combining the Monod and Nernst equations, Kato Marcus et al. [31] derived
the Nernst-Monod equation to describe current density in response to the
electrical potential of the anode E
anode
(V):
