Microbial Fuel Cell Experiment: Graphite Electrodes and Energy Production

Table of Contents
Introduction................................................................................................................ 1
Research aim.......................................................................................................... 2
Research Results..................................................................................................... 2
Electrode graphite agar........................................................................................ 2
Electrode graphite felt.......................................................................................... 3
Discussion............................................................................................................... 5
Recommendation to future studies.........................................................................6
List of reference......................................................................................................... 7
Introduction
At the moment, the world at large is facing energy problems due to insufficient
production of energy which also sourced from non-renewable sources such as nuclear
energy, fossils fuels, coal and natural gas which its mining and production according
Bulut.U 2017 hampers the environment by excessive production of carbon (iv) oxide
which depletes the ozone layer also increase global warming, main cause of acidic rain
water, pose health hazard to human beings and also it residuals are usually non-
biodegradable. A hundred percent dependence of non-renewable sources would leave
the world in a serious energy crisis should such source become depleted. It is therefore
important that the world observe and appreciate the use of renewable sources of energy
that are environmentally and health friendly and it would save the world the risk of
running out of energy sources since it does not get depleted.
Panwar.N 2011 proposed renewable sources of energy including wind power, solar,
geothermal and the microbial fuel cells. Pant.D 2010 defined microbial fuel cell mostly
known as MFCs are devices convert energy from respiring oxidizing agents and
microbes from anodes using cell bacteria to catalyze the chemical reaction to generate
electric current, performing a redox reaction. According to Winfield.J 2014 the use of
microbes to generate electric energy began at the early twentieth century around the
year 1910 by a university professor named M.C Potter. Potter succeeded using the
E.coli organism to generate electric energy. His success motivated thousands of other
scholars as the years eloped by who continued to lead massive developments in the
use of microbes to produce energy.
1

Numerous technological changes have been introduced since the invention of the
microbial fuel cell by MC. Potter. At the beginning of the 21st century scientist started
modifying the original experimental design configurations of the microbial fuels,
according to Karra.U 2013 this led to establishment of one chambered, two chambered,
tubular, h-type, and upflows Mfcs designs. The changing of the anodes and cathodes to
have a biological anode and abiotic cathodes joined by a porous proton layer with
experimental mediators of electrons and redox reaction temperature control resulted in
increasing the power outputs produced and easier way of controlling the experimental
residues such as toxicity and materials such as the oxygen.
The most used organisms in performing of the microbial fuel growth experiments
includes: E.coli, enterobacter and Citrobacter Freundii. Their scientific names are
Escherichia coli, Enterobacter and Citrobacter freundii respectively. Amazingly all the
organisms are placed under the same phylum Proteobacteria, family
Enterobacteriaceae and order Enterobacteriales. Their phylum mostly constitutes of
pathogens. It is believed that the organisms namely; E.coli, enterobacter and
Citrobacter Freundii can be helpful to the world by creating sources of sufficient
renewable energy and also help in treatment of waste water. This lab report is
interested in examining the abilities of the three organisms to generate electric energy
by using two different graphite electrodes. The Mfcs experiment is dived into four
experimental parts namely the anode part where the bacteria are held, the cathode part
which holds the reacting agents, the proton layer part which separates the anode and
the cathode and controls protons movements and the last part electric circuit part.
Research aim
The aim of the research is to demonstrate the use E.coli, enterobacter and Citrobacter
Freundii to produce electric energy.
Research Results
The experiment was conducted three times in two dimensions using the agar and felt
graphite electrodes. The results were recorded after one week a period of 168 hours.
The voltage is measured in mV units. The following results were obtained;
Electrode graphite agar
The following results were obtained on the organisms: Citrobacter Freundii,
enterobacter and E.coli having generated electric voltage of 109.7, 47.1, 85.5 on
experiment one, 105, 136, 21.1 on experiment two and 10, 61.5 and 72.4 on experiment
three respectively.
2

The results are summarized in the table below
agar
organism pract
1
pract
2
pract
3
averag
e
sd
citrobactor freundii 109.7 105 10 74.9 56.2541
6
enterbacter 47.1 136 61.5 81.53 47.7158
6
e.coli 85.5 21.1 72.4 59.66 34.0359
1
Electrode graphite felt
The following results were obtained on the organisms: Citrobacter Freundii,
enterobacter and E.coli having generated electric voltage of 124.8, 133.7, 21.1 on
experiment one, 56.3, 139.3, 21.1 on experiment and 106.7, 75.7 and 300 on
experiment three respectively.
felt
sorganism pract
1
pract
2
pract
3
averag
e
SD
citrobactor freundii 124.8 56.3 106.7 95.93 35.4965
3
enterbacter 133.7 139.3 75.7 116.23
3
35.2143
9
e.coli 21.1 21.1 300 114.06
6
161.023
3