hurdles through innovate research, it is feasible to produce high energy oil feedstocks which act as transportation fuels from algal biomass. We need to build
biomass production systems which can produce the highest yields with the lowest
inputs in future to gain more energy return on investment and to improve carbon
capture efficiency [66].
The synergistic model based on production of algae biofuel combined with urban
and agricultural wastewater bioremediation addresses many economic hurdles in
earlier algal systems and encourages value-added products [67, 68]. The strains of
dominant algae usually found in wastewater ponds include Chlorella, Actinastrum,
Scenedesmus, Selenastrum and Euglena. They are capable of extracting organic
matter and nutrients from wastewater, grow quickly, and generate biomass.
Municipal sewage water, agricultural wastewater, and livestock waste slurries
contain elevated amounts of P and N, which can potentially be utilized by
microalgae for biodiesel production. In a study, Botryococcus braunii have effectively removed nitrate (up to 80%) and displayed higher growth rates in piggery
wastewater consisting of 800 mg L
À1 nitrates [69]. Microalgae are having the ability
to grow in effluents of industries such as tanneries, textile industries, agro-industries,
distilleries, and pulp and paper industries which may contain high concentrations of
organic material (carbohydrate, starch, cellulose, hemicelluloses), harmful microorganisms, toxic heavy metals, etc. [70]. Normally effluents from industries may
contain high COD and BOD, and there are variations in chemical compositions
from one industry to another. Waters produced from meat processing industry
consists of antibiotics, hormones, body fluids, and other organic waste while simple
sugars are present in confectionary wastewaters. Waters from pulp and paper
industries are polluted with high concentrations of suspended solids, which are
rich in inorganic acid and alkali salts.
10 Bioenergy Options from Microalgal Biomass
Algal biomass presents four modes of energy production such as (a) biomass
anaerobic digestion to produce methane (biogas); (b) thermo-chemical liquefaction
of biomass to produce bio-oil; (c) biomass lipid extraction and transesterification to
produce biodiesel; and (d) fermentation of carbohydrate and bioethanol production
via distillation [71–73]. The complete transformation steps of biomass to various
energy resources are represented in Fig. 4.
The lipid biomass extraction and transesterification is one of the most widely
followed bioenergy production routes. This mode of biofuel production demands
relatively higher lipid content in the alga biomass. Many times transesterification is a
costlier process due to parameters like catalyst ratio, solvent requirement, and high
process temperatures leading to negative energy balance, that is, higher input energy
over output energy, nearly 2 [71].
By adopting a biorefinery approach, the sustainability and economic viability of
the production of biodiesel from microalgal biomass can be greatly improved. This
Algal Biomass for Biofuels and Bioproducts
153
biomass production systems which can produce the highest yields with the lowest
inputs in future to gain more energy return on investment and to improve carbon
capture efficiency [66].
The synergistic model based on production of algae biofuel combined with urban
and agricultural wastewater bioremediation addresses many economic hurdles in
earlier algal systems and encourages value-added products [67, 68]. The strains of
dominant algae usually found in wastewater ponds include Chlorella, Actinastrum,
Scenedesmus, Selenastrum and Euglena. They are capable of extracting organic
matter and nutrients from wastewater, grow quickly, and generate biomass.
Municipal sewage water, agricultural wastewater, and livestock waste slurries
contain elevated amounts of P and N, which can potentially be utilized by
microalgae for biodiesel production. In a study, Botryococcus braunii have effectively removed nitrate (up to 80%) and displayed higher growth rates in piggery
wastewater consisting of 800 mg L
À1 nitrates [69]. Microalgae are having the ability
to grow in effluents of industries such as tanneries, textile industries, agro-industries,
distilleries, and pulp and paper industries which may contain high concentrations of
organic material (carbohydrate, starch, cellulose, hemicelluloses), harmful microorganisms, toxic heavy metals, etc. [70]. Normally effluents from industries may
contain high COD and BOD, and there are variations in chemical compositions
from one industry to another. Waters produced from meat processing industry
consists of antibiotics, hormones, body fluids, and other organic waste while simple
sugars are present in confectionary wastewaters. Waters from pulp and paper
industries are polluted with high concentrations of suspended solids, which are
rich in inorganic acid and alkali salts.
10 Bioenergy Options from Microalgal Biomass
Algal biomass presents four modes of energy production such as (a) biomass
anaerobic digestion to produce methane (biogas); (b) thermo-chemical liquefaction
of biomass to produce bio-oil; (c) biomass lipid extraction and transesterification to
produce biodiesel; and (d) fermentation of carbohydrate and bioethanol production
via distillation [71–73]. The complete transformation steps of biomass to various
energy resources are represented in Fig. 4.
The lipid biomass extraction and transesterification is one of the most widely
followed bioenergy production routes. This mode of biofuel production demands
relatively higher lipid content in the alga biomass. Many times transesterification is a
costlier process due to parameters like catalyst ratio, solvent requirement, and high
process temperatures leading to negative energy balance, that is, higher input energy
over output energy, nearly 2 [71].
By adopting a biorefinery approach, the sustainability and economic viability of
the production of biodiesel from microalgal biomass can be greatly improved. This
Algal Biomass for Biofuels and Bioproducts
153