143
phototrophic- heterotrophic cathode biofilm from a sediment microbial fuel cell
(SMFC). Molecular taxonomic analysis showed that the presence of cyanobacteria
and microalgae predominated in the water phase as photosynthetic organisms along
with dominance of electrogenic population in sediment for electricity generation.
Application of MSC with reversible biocathode was proposed by Strik et al. [28] to
address the issue of pH imbalance across the membrane due to acid formation at
anode and alkali formation at cathode. Micro-sized MSC (57-μL) through photosynthetic reactions of cyanobacteria Synechocystis sp. PCC 6803 in the anodic
chamber was capable to generate the power density of 7.09 nW/cm
2
[29]. The photosynthetic organism, i.e., cyanobacteria, serves as a sustainable and effective catalyst for cathodic reactions in MSC, similar to the photosynthesis process in plants.
Such advanced MSC in combination with photoelectric cell is useful to produce
electricity, methane, hydrogen, and other biofuels during wastewater treatment [30].
5.4 Paddy Field MFC
Apart from rice as food source, environmental concern has been raised with emission of methane from paddy field. From this point of view, several research studies
have been conducted on application of MFC in paddy field for in situ electricity
generation, methane emission, and wastewater treatment. PMFC with rice plants
(Oryza sativa L.) and biochar anode produced power density of 11.1 mW/m
2
along
with reduction in methane emission by 39% and were found to be effective as compared to soil-based MFC [31]. In reality, paddy MFC is more suitable in sediment
conditions due to availability of high organic matter in soil. In such MFC, anode is
set in paddy field before rice transplantation. Rhizosphere microbe oxidizes photosynthesized organic matter excreted from rice roots and generates electron for
energy recovery [32]. Current production in paddy MFC reduced methane generation by half when operated in closed circuit conditions as compared to MFC with
open circuit conditions [33]. The microbial taxonomic analyses revealed the presence of Desulfobulbus, Geobacter sp., Methanobacterium, and Clostridiaceae
microbes in paddy field suitable for MFC applications.
5.5 Floating Islands
Floating island is generally an artificially constructed MFC in hydroponic system
for plant growth and wastewater treatment and serves as a polishing treatment for
the removal of organic matter and nutrient content from wastewater. Such system is
capable to remove the contaminants from effluent stream intermittently with effective heavy metal removal. Recently, Yadav et al. [34] developed integrated drip
hydroponic MFC system for treatment of domestic wastewater. Such system
achieved ammonia, COD, and phosphate removal efficiency of 35%, 83%, and
Plant Microbial Fuel Cell as a Biomass Conversion Technology for Sustainable…
phototrophic- heterotrophic cathode biofilm from a sediment microbial fuel cell
(SMFC). Molecular taxonomic analysis showed that the presence of cyanobacteria
and microalgae predominated in the water phase as photosynthetic organisms along
with dominance of electrogenic population in sediment for electricity generation.
Application of MSC with reversible biocathode was proposed by Strik et al. [28] to
address the issue of pH imbalance across the membrane due to acid formation at
anode and alkali formation at cathode. Micro-sized MSC (57-μL) through photosynthetic reactions of cyanobacteria Synechocystis sp. PCC 6803 in the anodic
chamber was capable to generate the power density of 7.09 nW/cm
2
[29]. The photosynthetic organism, i.e., cyanobacteria, serves as a sustainable and effective catalyst for cathodic reactions in MSC, similar to the photosynthesis process in plants.
Such advanced MSC in combination with photoelectric cell is useful to produce
electricity, methane, hydrogen, and other biofuels during wastewater treatment [30].
5.4 Paddy Field MFC
Apart from rice as food source, environmental concern has been raised with emission of methane from paddy field. From this point of view, several research studies
have been conducted on application of MFC in paddy field for in situ electricity
generation, methane emission, and wastewater treatment. PMFC with rice plants
(Oryza sativa L.) and biochar anode produced power density of 11.1 mW/m
2
along
with reduction in methane emission by 39% and were found to be effective as compared to soil-based MFC [31]. In reality, paddy MFC is more suitable in sediment
conditions due to availability of high organic matter in soil. In such MFC, anode is
set in paddy field before rice transplantation. Rhizosphere microbe oxidizes photosynthesized organic matter excreted from rice roots and generates electron for
energy recovery [32]. Current production in paddy MFC reduced methane generation by half when operated in closed circuit conditions as compared to MFC with
open circuit conditions [33]. The microbial taxonomic analyses revealed the presence of Desulfobulbus, Geobacter sp., Methanobacterium, and Clostridiaceae
microbes in paddy field suitable for MFC applications.
5.5 Floating Islands
Floating island is generally an artificially constructed MFC in hydroponic system
for plant growth and wastewater treatment and serves as a polishing treatment for
the removal of organic matter and nutrient content from wastewater. Such system is
capable to remove the contaminants from effluent stream intermittently with effective heavy metal removal. Recently, Yadav et al. [34] developed integrated drip
hydroponic MFC system for treatment of domestic wastewater. Such system
achieved ammonia, COD, and phosphate removal efficiency of 35%, 83%, and
Plant Microbial Fuel Cell as a Biomass Conversion Technology for Sustainable…