Biomedical Engineering Reference
In-Depth Information
4.2 Future Directions
4.2.1 Microbiology Insight and Manipulation
It is quite possible that MFCs will one day be used as a stand-alone technology for
power generation and waste treatment, but the capabilities of such technologies are
currently limited by a couple of technological and economic challenges. In fact, we
are not yet at the upper limits of maximum power densities of MFCs.
To overcome these challenges and limitations, we need a better understanding of the
bacteria that metabolize various substrates and transfer electrons to the anode [
118
].
Moreover, an in-depth knowledge of the acclimatization of the communities in
MFCs and their response to environmental disturbances would reduce the perceived
risks and accelerate the startup of MFCs. Thus, it is crucial to investigate the bio-
chemical pathways and bacterial physiology of electricigens. With this deep insight,
it would then be possible for us to derive more quantitative methods for rationally
designing the composition of microbial communities, and to offer a better manipu-
lation of the biological and electrochemical processes at molecular levels. Specifi-
cally, mining of functional genes and effective metabolic engineering approaches
would allow better manipulation of the electron flow and the creation of a highly
catalytic interface between electrode and microorganisms.
4.2.2 Process Modeling and Control
Modeling provides another useful tool for exploring the underlying scenario of
substrate metabolism and electron flow and also a reliable foundation for process
monitoring and control. Indeed, mathematical modeling does have the potential to
inform an MFC process; however, the many uncertainties in the function of
microorganisms may present the greatest barrier [
119
]. Mathematical modeling
can be suitably employed to reduce the burden on laboratory-based testing and
characterization. There are only a few modeling investigations of MFCs [
120
].
A more reliable model based on the microbial metabolism and biochemical pro-
cess should be considered, but the processes are too complex. Recently, a much
simpler electrochemical model of MFCs was established based on the polarization
curve [
121
], which revealed that the most important factors influencing MFCs
were reaction kinetic loss and mass transport loss. A better control of the kinetics
would thus be possible according to this study.
In the light of the instability of MFCs during long-term operation, it is nec-
essary to offer in-time monitoring and control of the MFC system. In this regard,
MFCs have a unique advantage because the electricity output can hopefully serve
as a useful indicator of the system operation status. With a better understanding of
the relationships between operation conditions, microbial activity, and electrical
responses through modeling analysis, a real-time monitoring and control of the
MFC's operation would be possible.
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