Keywords Algal biotreatment · Wastewater treatment · Merits and demerits ·
Emerging issues · Commercialization
1 Introduction
Industries are the key players in the economy of the developing countries; however,
these are also the major polluters worldwide due to their discharge of potentially toxic
wastewaters containing various organic and inorganic pollutants causing health threats
(Saxena et al. 2019; Bharagava et al. 2017a, b; Saxena and Bharagava 2017; Chandra
et al. 2015). Immediate importance for water conservation is evident due to the need
for sustainable development and to tackle the world’s increasing population where
water demand is also increasing. Consumption of freshwater has been estimated to be
~3.98 trillion m
3 (2014) globally, comprising 41%, 44%, and 15% of agriculture,
domestic, and industry use, respectively (World Bank 2016). Mateo-Sagasta et al.
(2015) reported that only approximately 60% of municipal wastewater is treated due to
lack of data from lower-income countries according to a World Bank census. Also,
inappropriate treatment of wastewaters without meeting the discharge limits set by the
environmental agencies can lead to serious public health risks. For instance, lowerincome countries constantly risk pathogenic infections which are abundant in
wastewater systems (Keraita et al. 2015). Conventional wastewater treatment
(WWT) systems operate with aerobic or anaerobic processes to reduce the contaminant load and make water available for reuse. However, the process is considered to be
highly energy intensive and supports the antagonist emission that affects the environment. For instance, to treat 500 Mm
3
year
À1 of domestic wastewater, the associated
expense was 50% higher with an average energy consumption of 0.5 kWhm
À3 (Acién
et al. 2016). Although conventional systems address nutrient removal to a certain
extent based on the different processes involved, the water bodies receiving excess
nutrients are prone to eutrophication (Al-Shannag et al. 2013). To prevent this, strict
guidelines based on NRC (2012) have endorsed the residual nitrogen and phosphates
with 5 mg l
À1 and 1 mg l
À1
, respectively.
During the 1950s, Oswald found that microalgae associated with bacteria in
lagoons subjected to aerobic treatment using wastewater treatment (WWT) systems
led to phycoremediation (Oswald et al. 1957). Hence, microalgae potential of
wastewater treatment has become the focus of much research since this method
requires carbon (C), nitrogen (N), and phosphates (P) for their growth based on
biochemical properties (Geider and Roche 2002). Moreover, the utilization of
nitrogen and phosphates, especially from WWT, could generate more biomass
than a normal system; this could constitute a valuable improvement to the method
(Olguín 2012). Nevertheless, there are always fluctuations in the wastewater composition due to nutrient limitation factors such as nitrogen and phosphates, and
especially with reference to microalgae cultivation (Whitton et al. 2016). For
instance, the growth of microalgae can decrease due to the limitation of phosphates
306
J. Umamaheswari et al.
Emerging issues · Commercialization
1 Introduction
Industries are the key players in the economy of the developing countries; however,
these are also the major polluters worldwide due to their discharge of potentially toxic
wastewaters containing various organic and inorganic pollutants causing health threats
(Saxena et al. 2019; Bharagava et al. 2017a, b; Saxena and Bharagava 2017; Chandra
et al. 2015). Immediate importance for water conservation is evident due to the need
for sustainable development and to tackle the world’s increasing population where
water demand is also increasing. Consumption of freshwater has been estimated to be
~3.98 trillion m
3 (2014) globally, comprising 41%, 44%, and 15% of agriculture,
domestic, and industry use, respectively (World Bank 2016). Mateo-Sagasta et al.
(2015) reported that only approximately 60% of municipal wastewater is treated due to
lack of data from lower-income countries according to a World Bank census. Also,
inappropriate treatment of wastewaters without meeting the discharge limits set by the
environmental agencies can lead to serious public health risks. For instance, lowerincome countries constantly risk pathogenic infections which are abundant in
wastewater systems (Keraita et al. 2015). Conventional wastewater treatment
(WWT) systems operate with aerobic or anaerobic processes to reduce the contaminant load and make water available for reuse. However, the process is considered to be
highly energy intensive and supports the antagonist emission that affects the environment. For instance, to treat 500 Mm
3
year
À1 of domestic wastewater, the associated
expense was 50% higher with an average energy consumption of 0.5 kWhm
À3 (Acién
et al. 2016). Although conventional systems address nutrient removal to a certain
extent based on the different processes involved, the water bodies receiving excess
nutrients are prone to eutrophication (Al-Shannag et al. 2013). To prevent this, strict
guidelines based on NRC (2012) have endorsed the residual nitrogen and phosphates
with 5 mg l
À1 and 1 mg l
À1
, respectively.
During the 1950s, Oswald found that microalgae associated with bacteria in
lagoons subjected to aerobic treatment using wastewater treatment (WWT) systems
led to phycoremediation (Oswald et al. 1957). Hence, microalgae potential of
wastewater treatment has become the focus of much research since this method
requires carbon (C), nitrogen (N), and phosphates (P) for their growth based on
biochemical properties (Geider and Roche 2002). Moreover, the utilization of
nitrogen and phosphates, especially from WWT, could generate more biomass
than a normal system; this could constitute a valuable improvement to the method
(Olguín 2012). Nevertheless, there are always fluctuations in the wastewater composition due to nutrient limitation factors such as nitrogen and phosphates, and
especially with reference to microalgae cultivation (Whitton et al. 2016). For
instance, the growth of microalgae can decrease due to the limitation of phosphates
306
J. Umamaheswari et al.