4.3.4 Microalgae as Aquaculture Feed
The primary applications of microalgae in aquaculture are linked to nutrition as sole
component/as a food additive to necessary nutrients. Some algae species commonly
used for aquaculture are Chlorella, Tetraselmis, Isochrysis, Pavlova,
Phaeodactylum, Chaetoceros, Nannochloropsis, Skeletonema, and Thalassiosira.
Natural pigments obtained from Dunaliella salina, Haematococcus pluvialis, and
Spirulina are used for coloring the flesh, in order to induce the biological activities of
prawns, salmonid fish, ornamental fish, etc. A protein-rich diet is supplemented and
tested with shrimp through microalgae species Hypnea cervicornis and Cryptonemia
crenulata (Spolaore et al. 2006).
4.3.5 Microalgae as Energy Reserve
High lipid and carbohydrate content of microalgae biomass make it suitable for
energy extraction. Moreover, the quantity of oil production from microalgae biomass
is comparable to the yield of the best oilseed crops. For instance, biodiesel yield from
microalgae (containing 30% oil by it) is 58,700 l ha
À1 compared with 1190 l ha
À1
from rapeseed, 1892 l ha
À1 from Jatropha, and 2590 l ha
À1 from Karanj (Singh and
Gu 2010). Botryococcus braunii, Isochrysis sp., Nannochloropsis sp.,
Schizochytrium sp., Nitzschia sp., Chlorella sp., and Neochloris oleoabundans are
a few examples of microalgae with higher oil content. There are two crucial ways by
which microalgal biomass is converted into energy, and these are thermochemical
and biochemical conversion processes. In thermochemical conversion, thermal
decomposition of biomass into fuel products (such as syngas, bio-oil, charcoal,
and electricity) is achieved by various methods, viz., combustion, gasification, and
liquefaction. The process of biochemical conversion of biomass into energy fuels
(methane, hydrogen, and ethanol) includes anaerobic digestion, alcoholic
fermentation, and photobiological hydrogen production. Selecting the conversion
process depends on the following factors: type and quantity of biomass feedstock;
form of energy; end product required; and economic considerations (Brennan and
Owende 2010).
5 Possibilities and Future Needs of Algal Technology
in Wastewater Treatment
The positive impact of phycoremediation based on the above literature studies
indicates that it is an efficient strategy for WWT processes. However, these processes have so far been carried out in pilot-scale tests and are yet to be applied to
WWT plants. The continuous flow of water in WWT systems and the demand to
treat a million liters per day (MLD) have led to the focus on improving retention
13 Phycoremediation: An Integrated and Eco-friendly Approach for. . .
325
The primary applications of microalgae in aquaculture are linked to nutrition as sole
component/as a food additive to necessary nutrients. Some algae species commonly
used for aquaculture are Chlorella, Tetraselmis, Isochrysis, Pavlova,
Phaeodactylum, Chaetoceros, Nannochloropsis, Skeletonema, and Thalassiosira.
Natural pigments obtained from Dunaliella salina, Haematococcus pluvialis, and
Spirulina are used for coloring the flesh, in order to induce the biological activities of
prawns, salmonid fish, ornamental fish, etc. A protein-rich diet is supplemented and
tested with shrimp through microalgae species Hypnea cervicornis and Cryptonemia
crenulata (Spolaore et al. 2006).
4.3.5 Microalgae as Energy Reserve
High lipid and carbohydrate content of microalgae biomass make it suitable for
energy extraction. Moreover, the quantity of oil production from microalgae biomass
is comparable to the yield of the best oilseed crops. For instance, biodiesel yield from
microalgae (containing 30% oil by it) is 58,700 l ha
À1 compared with 1190 l ha
À1
from rapeseed, 1892 l ha
À1 from Jatropha, and 2590 l ha
À1 from Karanj (Singh and
Gu 2010). Botryococcus braunii, Isochrysis sp., Nannochloropsis sp.,
Schizochytrium sp., Nitzschia sp., Chlorella sp., and Neochloris oleoabundans are
a few examples of microalgae with higher oil content. There are two crucial ways by
which microalgal biomass is converted into energy, and these are thermochemical
and biochemical conversion processes. In thermochemical conversion, thermal
decomposition of biomass into fuel products (such as syngas, bio-oil, charcoal,
and electricity) is achieved by various methods, viz., combustion, gasification, and
liquefaction. The process of biochemical conversion of biomass into energy fuels
(methane, hydrogen, and ethanol) includes anaerobic digestion, alcoholic
fermentation, and photobiological hydrogen production. Selecting the conversion
process depends on the following factors: type and quantity of biomass feedstock;
form of energy; end product required; and economic considerations (Brennan and
Owende 2010).
5 Possibilities and Future Needs of Algal Technology
in Wastewater Treatment
The positive impact of phycoremediation based on the above literature studies
indicates that it is an efficient strategy for WWT processes. However, these processes have so far been carried out in pilot-scale tests and are yet to be applied to
WWT plants. The continuous flow of water in WWT systems and the demand to
treat a million liters per day (MLD) have led to the focus on improving retention
13 Phycoremediation: An Integrated and Eco-friendly Approach for. . .
325