92
A. A. S. Al-Gheethi et al.
the algae growth. Moreover, the algae biomass generated during the cultivation has
several applications as a fuel production and pharmaceutical product. Another advantage of the green technology of algae is the high potential for treating wastewater
and removing nutrients, organic pollutants, and heavy metals. In terms of bioelectricity generated from the algae, it depends on the algae activity and growth, such as
metabolic pathways and photosynthesis process which associate with the release of
oxygen through metabolic pathways and photosynthesis of the microalgae. In more
critical details, the light wavelength and period are playing vital role in the amount
of bioelectricity production (Luo et al. 2017; Saratale et al. 2017). Several algae
species have been used in the MFC components as cathode and anode. However, in
many studies, the algae are used as cathodes, Chlamydomonas reinhardtii, Chlorella
vulgaris, Spirulina platensis, Pseudokirchneriella subcapitata, and Anabaena sp. are
among the algae reported in literature (Strik et al. 2009; Zhou et al. 2012; Fu et al.
2009; Xiao et al. 2012; Pandit et al. 2012).
Bazdar et al. (2018) used Chlorella vulgaris to develop a photosynthetic microalgae microbial fuel cell (PMMFC) for production of bioelectricity and biomass as
well as for treating wastewater as a response for different light intensities (3500–
10,000 lx) and periods (24/00, 12/12, 16/8 h dark/light). The study revealed that
126 mW m
−3 of electricity was produced, while 78, 5.47% of the Coulombic efficiency and COD removal were recorded. In contrast, the biomass yield is correlated
with the light intensity up to 10,000 lx. However, authors in literature mentioned that
the dark period is required to maintain the health of algae cells. Therefore, in many
studies, the algae cells used for bioelectricity are incubated under 16/8 h light/dark
cycle (Wu et al. 2013).
Several studies have been designed and developed for harvesting of bioenergy
from photocatalysis process of algae. Subhash et al. (2013) developed a singlechambered autotrophic photo-bioelectrocatalytic fuel cells (PhFCOX). Nafion-117
has been used as a proton exchange membrane (PEM) and sandwiched between the
anode which was totally immersed in the wastewater samples, where cathode was
exposed to the air at the top and immersed in the wastewater at the bottom. The
biocatalyst used in the study was algae consortium inoculated into the PhF COX with
wastewater and incubated at ambient temperature (12 h light/12 h/dark). The pH was
adjusted to pH 7. The electricity activity was assessed in terms of voltage, current, and
electron discharges. The study revealed that the maximum voltage generated reached
up to 38 mV and 0.1 mA after 120 h. Gouveia et al. (2014) investigated the production
of bioelectricity in MFCs via Chlorella vulgaris as a cathode and bacterial consortium
as an anode. The study revealed that the production of bioelectricity associated with
the light intensity ranged from 26 to 96 lE/(m
2 s), and the maximum production was
62.7 mW/m
2 recorded with 96 lE/(m
2 s) of the light intensity.
In many studies, the microalgae–microbial fuel cell system combined microalgae
and bacteria. Huarachi-Olivera et al. (2018) suggested that microalgae–microbial fuel
cell using C. vulgaris and bacterial community exhibited a simultaneous efficiency in
the production of bioelectricity and bioremediation processes. The MFCs produced
bioenergy ranging from 23.17 to 327.67 mW/m
2 on 32 d. Therefore, the MFCs
represent an important source of bioenergy.
A. A. S. Al-Gheethi et al.
the algae growth. Moreover, the algae biomass generated during the cultivation has
several applications as a fuel production and pharmaceutical product. Another advantage of the green technology of algae is the high potential for treating wastewater
and removing nutrients, organic pollutants, and heavy metals. In terms of bioelectricity generated from the algae, it depends on the algae activity and growth, such as
metabolic pathways and photosynthesis process which associate with the release of
oxygen through metabolic pathways and photosynthesis of the microalgae. In more
critical details, the light wavelength and period are playing vital role in the amount
of bioelectricity production (Luo et al. 2017; Saratale et al. 2017). Several algae
species have been used in the MFC components as cathode and anode. However, in
many studies, the algae are used as cathodes, Chlamydomonas reinhardtii, Chlorella
vulgaris, Spirulina platensis, Pseudokirchneriella subcapitata, and Anabaena sp. are
among the algae reported in literature (Strik et al. 2009; Zhou et al. 2012; Fu et al.
2009; Xiao et al. 2012; Pandit et al. 2012).
Bazdar et al. (2018) used Chlorella vulgaris to develop a photosynthetic microalgae microbial fuel cell (PMMFC) for production of bioelectricity and biomass as
well as for treating wastewater as a response for different light intensities (3500–
10,000 lx) and periods (24/00, 12/12, 16/8 h dark/light). The study revealed that
126 mW m
−3 of electricity was produced, while 78, 5.47% of the Coulombic efficiency and COD removal were recorded. In contrast, the biomass yield is correlated
with the light intensity up to 10,000 lx. However, authors in literature mentioned that
the dark period is required to maintain the health of algae cells. Therefore, in many
studies, the algae cells used for bioelectricity are incubated under 16/8 h light/dark
cycle (Wu et al. 2013).
Several studies have been designed and developed for harvesting of bioenergy
from photocatalysis process of algae. Subhash et al. (2013) developed a singlechambered autotrophic photo-bioelectrocatalytic fuel cells (PhFCOX). Nafion-117
has been used as a proton exchange membrane (PEM) and sandwiched between the
anode which was totally immersed in the wastewater samples, where cathode was
exposed to the air at the top and immersed in the wastewater at the bottom. The
biocatalyst used in the study was algae consortium inoculated into the PhF COX with
wastewater and incubated at ambient temperature (12 h light/12 h/dark). The pH was
adjusted to pH 7. The electricity activity was assessed in terms of voltage, current, and
electron discharges. The study revealed that the maximum voltage generated reached
up to 38 mV and 0.1 mA after 120 h. Gouveia et al. (2014) investigated the production
of bioelectricity in MFCs via Chlorella vulgaris as a cathode and bacterial consortium
as an anode. The study revealed that the production of bioelectricity associated with
the light intensity ranged from 26 to 96 lE/(m
2 s), and the maximum production was
62.7 mW/m
2 recorded with 96 lE/(m
2 s) of the light intensity.
In many studies, the microalgae–microbial fuel cell system combined microalgae
and bacteria. Huarachi-Olivera et al. (2018) suggested that microalgae–microbial fuel
cell using C. vulgaris and bacterial community exhibited a simultaneous efficiency in
the production of bioelectricity and bioremediation processes. The MFCs produced
bioenergy ranging from 23.17 to 327.67 mW/m
2 on 32 d. Therefore, the MFCs
represent an important source of bioenergy.