6 Microbial Fuel Cells: A Green and Alternative Source …
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(RS), and wastewater (WW) in MFCs. The study recorded a different power generation with different bacterial densities, while the bacterial community from the RS
generated maximum power density (744.8 mW m
−2 ), followed by bacterial from
AS, GS, and WW. Based on the principal component analysis (PCA), the microbes
in MFC-AS and MFC-GS were closely clustered but separated from MFC-WW to
MFC-RS. The majority of microbes in RS was Azoarcus (45.20%), while Flavobacterium (14.18%) in AS, Geobacter (14.40%) in GS, and Azovibrio (11.11%) in WW.
It can be concluded that the initial concentrations of bacteria and the source play
important role in the amount of bioenergy generated in MFCs.
Velasquez-Orta et al. (2009) compared bioelectricity production between
Chlorella vulgaris and Ulva lactuca. The study revealed that C. vulgaris was more
efficient in producing energy (2.5 kWh/kg) compared to U. lactuca. The maximum
power densities obtained by C. vulgaris were 0.98 W/m/(277 W/m), while were
0.76 W/m/(215 W/m) by U. lactuca in single and multiple cycle methods, respectively. These findings confirmed that the production of bioenergy is dependent on
the algae species which have different metabolic activities.
6.3.4 Effect of Environmental Conditions
The environmental factors affecting microbial fuel cell efficiency are similar to the
factors affecting microbial growth such as pH, temperature, ionic strength, light, and
salt. Factors which improve the microbial growth also improve the MFC performance.
Salt has negative effect on the microbial growth; however, higher salinity and ionic
strength associate with the increasing conductivity of substrate and therefore enhance
the MFC performance (Aghababaie et al. 2015).
The effect of different light intensities on bioelectricity in a photosynthetic alga
microbial fuel cell (PAMFC) using Chlorella vulgaris was investigated by Gouveia
et al. (2014). In the study, C. vulgaris was used as a cathode compartment, while
the bacterial consortium was used in the anode. Two different light intensities were
investigated. The results revealed that the highest bioelectricity production was 62.7
mW/m
2 with 96 μE/(m
2 s) light intensity. However, the increase of the light intensity
from 26 to 96 μE/(m
2 s) was associated with the increase of bioelectricity production
by sixfolds.
Larrosa-Guerrero et al. (2010) studied the effect of temperature between 4 and
35 °C on the performance of MFCs with brewery wastewater as a substrate. The
study revealed that the temperature plays a crucial role in the electricity production
given the maximum power of 15.1 mW m
3 reactor at 4 °C to 174.0 mW m
3 reactor
at 35 °C. Liu et al. (2005) tested the energy recovery, power density, Coulombic efficiency, and electrode potential of MFCs as a function of electrode spacing, solution
ionic strength, temperature, and composition. The study revealed that power output
increased from 720 to 1330 mW/m
2 with the increase of ionic strength from 100 to
400 mM, decreasing the distance between the anode and cathode (4–2 cm). These
95
(RS), and wastewater (WW) in MFCs. The study recorded a different power generation with different bacterial densities, while the bacterial community from the RS
generated maximum power density (744.8 mW m
−2 ), followed by bacterial from
AS, GS, and WW. Based on the principal component analysis (PCA), the microbes
in MFC-AS and MFC-GS were closely clustered but separated from MFC-WW to
MFC-RS. The majority of microbes in RS was Azoarcus (45.20%), while Flavobacterium (14.18%) in AS, Geobacter (14.40%) in GS, and Azovibrio (11.11%) in WW.
It can be concluded that the initial concentrations of bacteria and the source play
important role in the amount of bioenergy generated in MFCs.
Velasquez-Orta et al. (2009) compared bioelectricity production between
Chlorella vulgaris and Ulva lactuca. The study revealed that C. vulgaris was more
efficient in producing energy (2.5 kWh/kg) compared to U. lactuca. The maximum
power densities obtained by C. vulgaris were 0.98 W/m/(277 W/m), while were
0.76 W/m/(215 W/m) by U. lactuca in single and multiple cycle methods, respectively. These findings confirmed that the production of bioenergy is dependent on
the algae species which have different metabolic activities.
6.3.4 Effect of Environmental Conditions
The environmental factors affecting microbial fuel cell efficiency are similar to the
factors affecting microbial growth such as pH, temperature, ionic strength, light, and
salt. Factors which improve the microbial growth also improve the MFC performance.
Salt has negative effect on the microbial growth; however, higher salinity and ionic
strength associate with the increasing conductivity of substrate and therefore enhance
the MFC performance (Aghababaie et al. 2015).
The effect of different light intensities on bioelectricity in a photosynthetic alga
microbial fuel cell (PAMFC) using Chlorella vulgaris was investigated by Gouveia
et al. (2014). In the study, C. vulgaris was used as a cathode compartment, while
the bacterial consortium was used in the anode. Two different light intensities were
investigated. The results revealed that the highest bioelectricity production was 62.7
mW/m
2 with 96 μE/(m
2 s) light intensity. However, the increase of the light intensity
from 26 to 96 μE/(m
2 s) was associated with the increase of bioelectricity production
by sixfolds.
Larrosa-Guerrero et al. (2010) studied the effect of temperature between 4 and
35 °C on the performance of MFCs with brewery wastewater as a substrate. The
study revealed that the temperature plays a crucial role in the electricity production
given the maximum power of 15.1 mW m
3 reactor at 4 °C to 174.0 mW m
3 reactor
at 35 °C. Liu et al. (2005) tested the energy recovery, power density, Coulombic efficiency, and electrode potential of MFCs as a function of electrode spacing, solution
ionic strength, temperature, and composition. The study revealed that power output
increased from 720 to 1330 mW/m
2 with the increase of ionic strength from 100 to
400 mM, decreasing the distance between the anode and cathode (4–2 cm). These