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application in the treatment of domestic water and industrial effluent. Moreover, due
to energy insecurity and worldwide environmental alarms, there is an emergent inter-
est to find out sustainable and clean energy source. Traditional biodegradation pro-
cesses focus on removing organic pollutants and not on extraction of energy from
waste. For overcoming these drawbacks, it is important to develop an alternate tech-
nology that will be used to recover precious energy for the sustainable operation.

8.5 Microbial fuel cell technology

MFC is one of the fascinating technologies not only used for the treatment of indus-
trial wastewater but also for the electricity production. The basic principle behind
this technology is the chemical energy compounds are converted into electrical
energy during decomposition of organic and inorganic matters with the help of cata-
lytic action of microorganisms. There are two categories of MFCs: one is mediator
and the other is mediator less. During the 20th century the first MFC was estab-
lished for transfer of electrons from the bacteria in the cell to the anode using
chemical mediator. Most advancement in MFC happened during the years of 1970s
called mediator-less type in which the direct electron transfer mechanisms are given
more attention, because bacteria have electrochemically active redox capacity to
transfer the electrons directly to the anode. After many years, MFC was used for
commercial purposes in the 21st century. MFC is like a bioreactor where microor-
ganisms are oxidizing the organic and inorganic matters present in the effluent and
produce electricity. Microorganism-generated electrons are transferred to the nega-
tive terminal and flow to the positive terminal connected by an external electrical
device containing a resistor. The MFC reactor may able to decompose the substrate
present in the anode chamber, either batch mode or fed-batch mode; else, the sys-
tem is considered to be a bio-battery. The generated electrons are to be transferred
to the anode electrode by electron transfer mechanisms. Working process of MFCs
is the electrons transferred to the cathode compartment through proton exchange
membrane (PEM) with protons and oxygen are provided by externally; clean water
is the final by-product. Due to the photosynthesis process, biomass comes to the
atmosphere. A component of fuel cell was described in Table 8.1.

Table 8.1 Basic components of microbial fuel cells.
Items Materials

Anode Graphite, graphite felt, carbon paper, carbon cloth
Cathode Graphite, graphite felt, carbon paper, carbon cloth, black
Anode chamber Glass
Cathode chamber Glass
Proton exchange membrane Ultrex, salt bridge, porcelain septum, solely electrolyte,
system Nafion
31
Electrode catalyst Pt, Pt black, MnO 2 ,Fe , electron mediator
immobilized on anode