and nitrogen (Choi and Lee 2015). This is despite the fact that the algae are able to
assimilate carbon (both organic and inorganic) under various metabolic pathways
(Perez-Garcia et al. 2011; Abinandan and Shanthakumar 2016). To scale up the
phycoremediation, raceway ponds and PBRs are viable and economical for the
remediation and biomass production processes (Xu et al. 2015).
Other environmental factors also contribute to limiting biomass productivity such
as light and temperature which can be controlled by artificial arrangements or design
modifications (Whitton et al. 2015). Predominantly, strains belonging to the
Chlorophyta division of green algae tend to exhibit effective remediation properties
and enhanced biomass productivity (Abinandan and Shanthakumar 2015). Nevertheless, the isolation of wild-type microalgae compared to other species may perform
better depending on other new factors which may affect the growth
(Subashchandrabose et al. 2011). Emerging contaminants (synthetic organic
chemicals) have recently received attention since their presence was predominantly
higher in WWT (Ahmed et al. 2017). Nonetheless, a study has proven that algae
have shown immense potential to remediate organic pollutants through various
mechanisms (Subashchandrabose et al. 2013).
In this review, we discuss the constructive role of microalgae in wastewater
treatment. Later, we identify and address the limitations of phycoremediation in
various sources of wastewater. Furthermore, critical evaluation of biomass application derived from WWT system has to be considered. Subsequently, the highlights in
the major implications of biomass in the form of adsorbents and coagulants for
WWT are stated. Using biomass to fuel application is emphasized as an alternative
application. Other products from the biomass are evaluated depending on their
commercial value. Lastly, the possibilities and future needs of phycoremediation
are noted so that more insights to commercialization can be obtained.
2 Microalgae in Wastewater Treatment
Microalgae are ubiquitous, single-celled organisms that grow abundantly in aquatic
and terrestrial habitats. Due to their biochemical properties, microalgae biomass has
great biofuel commercialization potential. Since the growth rates of algae are higher
than terrestrial plants, this identifies them as third-generation biofuels. However, the
major drawback is that the input of chemicals to cultivate algae does not lead to a net
profit value of biofuel. Wastewater has been shown to provide excess nutrients from
post-secondary treatment systems. The presence of nutrients in WWT has been
identified as the substitution of algae cultivation without any modifications. Thus,
much scientific data have been published with respect to various sources of wastewater generation for algae cultivation. Also, the algae consume carbon-di-oxide as
the carbon source, making the process as an eco-friendlier approach. From an
economic perspective, there is no requirement for an oxygen supply through blowers
as they release oxygen during the day. Roughly, estimates show that 100,000 species
of microalgae are available in the earth under various habitats.
13 Phycoremediation: An Integrated and Eco-friendly Approach for. . .
307
assimilate carbon (both organic and inorganic) under various metabolic pathways
(Perez-Garcia et al. 2011; Abinandan and Shanthakumar 2016). To scale up the
phycoremediation, raceway ponds and PBRs are viable and economical for the
remediation and biomass production processes (Xu et al. 2015).
Other environmental factors also contribute to limiting biomass productivity such
as light and temperature which can be controlled by artificial arrangements or design
modifications (Whitton et al. 2015). Predominantly, strains belonging to the
Chlorophyta division of green algae tend to exhibit effective remediation properties
and enhanced biomass productivity (Abinandan and Shanthakumar 2015). Nevertheless, the isolation of wild-type microalgae compared to other species may perform
better depending on other new factors which may affect the growth
(Subashchandrabose et al. 2011). Emerging contaminants (synthetic organic
chemicals) have recently received attention since their presence was predominantly
higher in WWT (Ahmed et al. 2017). Nonetheless, a study has proven that algae
have shown immense potential to remediate organic pollutants through various
mechanisms (Subashchandrabose et al. 2013).
In this review, we discuss the constructive role of microalgae in wastewater
treatment. Later, we identify and address the limitations of phycoremediation in
various sources of wastewater. Furthermore, critical evaluation of biomass application derived from WWT system has to be considered. Subsequently, the highlights in
the major implications of biomass in the form of adsorbents and coagulants for
WWT are stated. Using biomass to fuel application is emphasized as an alternative
application. Other products from the biomass are evaluated depending on their
commercial value. Lastly, the possibilities and future needs of phycoremediation
are noted so that more insights to commercialization can be obtained.
2 Microalgae in Wastewater Treatment
Microalgae are ubiquitous, single-celled organisms that grow abundantly in aquatic
and terrestrial habitats. Due to their biochemical properties, microalgae biomass has
great biofuel commercialization potential. Since the growth rates of algae are higher
than terrestrial plants, this identifies them as third-generation biofuels. However, the
major drawback is that the input of chemicals to cultivate algae does not lead to a net
profit value of biofuel. Wastewater has been shown to provide excess nutrients from
post-secondary treatment systems. The presence of nutrients in WWT has been
identified as the substitution of algae cultivation without any modifications. Thus,
much scientific data have been published with respect to various sources of wastewater generation for algae cultivation. Also, the algae consume carbon-di-oxide as
the carbon source, making the process as an eco-friendlier approach. From an
economic perspective, there is no requirement for an oxygen supply through blowers
as they release oxygen during the day. Roughly, estimates show that 100,000 species
of microalgae are available in the earth under various habitats.
13 Phycoremediation: An Integrated and Eco-friendly Approach for. . .
307