Microbial Fuel Cell (MFC) is a device that generates electricity from the metabolism of
bacteria simultaneously treats wastewater by decolourizing the azo dye in wastewater.
In this work, the effect of different external loads and bacterial loads were examined.
The maximum open circuit voltage generated was 390 mV by using 7 consortia of
bacteria while the maximum current generated was 50 µA using 10 Ω resistor. 97%
decolourization efficiency of 0.1 g/L of azo dye was achieved after 5 days of operation.
Besides, the maximum current density and power density achieved were 17.9 µA/cm2
and 460 µW/cm2
respectively. Polarization curve was plotted and Scanning Electron
Microscope was applied to visualize the bacterial community attachment onto the
graphite felt electrode. Cyclic voltammetry was applied to study the redox properties
of the Azo dye using microorganisms in MFC. Overall, these 7 bacterial strains used in
this work showed the capability in decolourizing the Azo dye simultaneously producing
electricity in MFC.
Due to high energy demand worldwide, finding an alternative renewable and
sustainable energy source is of great interest. Plant microbial fuel cell (P-MFC) is one
of the most promising methods to generate green energy. In P-MFC, a plant is placed
into the anode compartment. Mutual interaction between plant root rhizodeposits
and bacterial community results in the biofilm formation at the vicinity of the
rhizosphere area in plant root could be utilized to generate electricity. Indeed, in PMFC,
bacteria metabolize rhizodeposits into electrons and protons. These electrons
could be then converted into green electricity. The objectives of this research are to
utilize Epipremnum aureum plant collected from Kota Tinggi’s lake to generate
electricity and observe current generation by different resistors, to characterize
immobilized bacteria attached on the anode surface then identify the optimum growth
temperature for isolated bacteria. Five plant microbial fuel cells were constructed in a
H-shape (dual- chambers) configuration in the plastic container. Maximum current
density for 20 days for P-MFC by external resistance of 100k Ω was 0.1 µA/cm2
with
maximum power density of 0.85 µW/cm2 and the open circuit voltage (OCV) was
measured at 195 mV. Besides, fresh biomass averages increased 5g after 20 days of
experiments below and above ground as compared to the initial fresh biomass. Five
isolated bacterial strains from the graphite felt surface found on the anode were
screened by nine biochemical tests such as catalase, TSI (triple sugar iron agar), gelatin
and etc. The immobilized bacteria attached to anode electrode in P-MFC were further
examined with Fast Electron Scanning Electron Microscopy (FESEM). The isolated
bacterial growth curves were determined at two different temperatures of 25 °C and
37 °C. The optimum growth temperature predominantly for them was 37 °C.
In this study, we investigate the ability of the bacterial isolates from an Iraqi oil
reservoir, namely POS and PCO Oil to decolorize commercially used model azo dye Acid
Red-27(AR-27). The effects of inoculation volume and glycerol concentrations were
optimized to develop an economically feasible decolourization process. The isolates
were able to decolourize azo dye (AR27) at the highest decolorization efficiency of 98%
in 10 mL bacterial solution consisted of POS and PCO Oil and in the presence of 6.34
g/L glycerol. An optimized MFC using this bacterial consortium (POS + PCO Oil) and
graphite rod electrodes produced a maximum open circuit voltage (OCV) of 175 mV, in
the presence of potassium ferricyanide as the electron acceptor at the cathode. The
maximum current density of 1.7 μA/cm² and power density of 59.3 μW/cm² were
achieved when an external load of 5 kΩ was applied. Morphological analysis was
performed using Scanning Electron Microscope (SEM) to prove the bacterial
attachment onto the anode surface (graphite rod) in the MFC operation. This work
proposed that the bacterial strains POS and PCO Oil possess the ability to decolorize
Azo dye AR27 and generate electricity in the absence of nitrogen source.