operating conditions especially at ambient temperatures (Gude 2016). MFCs can
produce up to 1.43 kWh/m
3 from a primary sludge or 1.8 kWh/m
3 from a treated
effluent (Ge et al. 2015). MFCs consume only 0.024 kW or 0.076 kWh/kg COD in
average (mainly for feeding and mixing in the reactor), about one order of magnitude
less than activated sludge-based aerobic processes (~0.3 kW or 0.6 kWh/kg COD)
(Zhang et al. 2013a, b). It means MFCs consume only about 10% of the external
energy for their operation when compared with conventional activated sludge
process showing great potential for energy savings as well as possible energy
recovery from wastewater treatment (Gude 2016).
2.7 Constructed Wetland-Microbial Fuel System
Integrating CWs with a microbial fuel cell (MFC) for wastewater treatment and
electricity generation could be an innovative approach for the improved degradation
of pollutants. The integration of MFC with a CW will upgrade the CW to allow it to
be used for wastewater treatment and, simultaneously, electricity generation, making
the CWs more sustainable and environmentally friendly. According to a recent
study, a maximum power density of 15.73 mW m
À2 and maximum current density
of 69.75 mA m
À2 could be achieved during the treatment of synthetic wastewater
containing methylene blue dye (1000 mg l
À1 765) with 75% COD removal in an
integrated CW-MFC system planted with an ornamental plant, Canna indica (Yadav
et al. 2012). Oon et al. (2015) designed an integrated upflow constructed wetlandmicrobial fuel cell (UFCW-MFC) system planted with cattail for the simultaneous
wastewater treatment and electricity generation. According to their study, the
removal efficiencies of COD, NO 3
À
, and NH 4
+ were 100%, 40%, and 91%, respectively, with the maximum power density of 6.12 mW m
À2 and coulombic efficiency
of 8.6% at electrode spacing of anode 1 (A1) and cathode (15 cm). Fang et al. (2013)
studied the performance of a microbial fuel cell coupled constructed wetland system
for decolorization of azo dye and bioelectricity generation. They reported that the
planted CW-MFC system achieved the highest decolorization rate of about 91.24%
for azo dyes and a voltage output of about 610 mV.
2.8 Nano-bioremediation
Nano-bioremediation is the new concept that integrates the use of nanoparticles and
bioremediation for sustainable remediation of environmental pollutants in contaminant matrix (Cecchin et al. 2017). For instance, Le et al. (2015) conducted a study
for the degradation of a solution containing Aroclor 1248 (PCB) using nZVI
(1000 mg/L) and subsequently using biodegradation with bacterium, Burkholderia
xenovorans. The researchers obtained 89% degradation of the congeners after
application of nZVI. Subsequently, they observed a biodegradation of 90% in the
120
G. Saxena et al.
produce up to 1.43 kWh/m
3 from a primary sludge or 1.8 kWh/m
3 from a treated
effluent (Ge et al. 2015). MFCs consume only 0.024 kW or 0.076 kWh/kg COD in
average (mainly for feeding and mixing in the reactor), about one order of magnitude
less than activated sludge-based aerobic processes (~0.3 kW or 0.6 kWh/kg COD)
(Zhang et al. 2013a, b). It means MFCs consume only about 10% of the external
energy for their operation when compared with conventional activated sludge
process showing great potential for energy savings as well as possible energy
recovery from wastewater treatment (Gude 2016).
2.7 Constructed Wetland-Microbial Fuel System
Integrating CWs with a microbial fuel cell (MFC) for wastewater treatment and
electricity generation could be an innovative approach for the improved degradation
of pollutants. The integration of MFC with a CW will upgrade the CW to allow it to
be used for wastewater treatment and, simultaneously, electricity generation, making
the CWs more sustainable and environmentally friendly. According to a recent
study, a maximum power density of 15.73 mW m
À2 and maximum current density
of 69.75 mA m
À2 could be achieved during the treatment of synthetic wastewater
containing methylene blue dye (1000 mg l
À1 765) with 75% COD removal in an
integrated CW-MFC system planted with an ornamental plant, Canna indica (Yadav
et al. 2012). Oon et al. (2015) designed an integrated upflow constructed wetlandmicrobial fuel cell (UFCW-MFC) system planted with cattail for the simultaneous
wastewater treatment and electricity generation. According to their study, the
removal efficiencies of COD, NO 3
À
, and NH 4
+ were 100%, 40%, and 91%, respectively, with the maximum power density of 6.12 mW m
À2 and coulombic efficiency
of 8.6% at electrode spacing of anode 1 (A1) and cathode (15 cm). Fang et al. (2013)
studied the performance of a microbial fuel cell coupled constructed wetland system
for decolorization of azo dye and bioelectricity generation. They reported that the
planted CW-MFC system achieved the highest decolorization rate of about 91.24%
for azo dyes and a voltage output of about 610 mV.
2.8 Nano-bioremediation
Nano-bioremediation is the new concept that integrates the use of nanoparticles and
bioremediation for sustainable remediation of environmental pollutants in contaminant matrix (Cecchin et al. 2017). For instance, Le et al. (2015) conducted a study
for the degradation of a solution containing Aroclor 1248 (PCB) using nZVI
(1000 mg/L) and subsequently using biodegradation with bacterium, Burkholderia
xenovorans. The researchers obtained 89% degradation of the congeners after
application of nZVI. Subsequently, they observed a biodegradation of 90% in the
120
G. Saxena et al.