biodiesel production, the main objective of this chapter is to
present a landscape of the use of microalgae for bioconversion of industrial wastes into biodiesel feedstocks.
2 Microalgae as a Biodiesel Feedstock
The overexploitation of energetic natural resources has driven the research and development (R&D) sector to seek
alternative sources of energy to supply the growing demand
and reduce the dependence on fossil fuels. Environmentally
friendly fuels that do not harm human health and the
ecosystems are the focus of researchers around the world
(Ingrao et al. 2018). In particular, the biodiesel with properties similar to diesel, a non-renewable fuel widely used by
trucks, buses and tractors, and other machines that require
high power, is gaining more and more space. It is worth
highlight that among the advantages of biodiesel using is the
significant reduction in the emission of polluting gases,
providing thus a high environmental gain (Cavalheiro et al.
2020).
The substitution of non-renewable fuels by renewable
ones reflects helpful contributions to the economy and
preservation of the environment. As sustainable and renewable alternative sources of energy have been full-blown the
biofuels of the first, second, third, and fourth generations. The
biodiesel generated from the oilseeds is named first generation, generated from the non-edible inputs of second generation, and generated from the organisms with elevated lipid
synthesis of third generation. The fourth-generation biodiesel
production uses microorganisms genetically modified and is
an emerging approach (Kumar et al. 2020).
Currently, biodiesel produced from food sources, through
the exploitation of vegetable oils and others that are from an
edible source, is already being applied directly to diesel
engines, or in parallel with fossil diesel (Ayoola et al. 2019).
However, the use of arable lands is one of the disadvantages
of using these sources. With the current concerns of international agencies, related to hunger and a significant growth
in the price of foods, new sources have been explored, as is
the example of oleaginous microorganisms, among them
microalgae. These microorganisms have high synthesis and
lipid storage in their cells (Severo et al. 2019).
The benefit of biodiesel fabrication from microalgae
includes the fast growth of cultures, high oil productivity,
and utilization of non-arable land (Maroneze et al. 2019). As
potential biological agents, these microorganisms can valorize wasted resources, mitigate carbon dioxide (CO 2 ), and
the biomass generated can be utilized for biodiesel production (Patidar and Mishra 2017).
3 Low-Cost Waste as Feedstock for Biodiesel
The use of alternative fuels to oil products is promising in
reducing the negative environmental impacts caused by the
consumption of fossil fuels. The excessive use of these
causes an increase in greenhouse gas emissions; thus, the
focus of the research has become the development of
renewable and environmentally friendly technologies that
serve as a commercially available energy source (Rajaeifar
et al. 2016).
Biodiesel is a promising biofuel to replace diesel (Oh
et al. 2012). The use of oleaginous microorganisms is an
option for biodiesel production. It offers advantages due to
its short cultivation period, higher productivity, and similarity in the fatty acid composition with the vegetable oils
generally used (Alptekin 2017; Cho and Park 2018).
Oilseed microorganisms accumulate a high concentration
of lipids in their cells, many times greater than 20%, and
using organic and inorganic carbon sources; the metabolism
is carried out (Xu et al. 2015; Amara et al. 2016). Unfortunately, the cost of cultivating these microorganisms is very
high, hampering the economic viability of microbial oils
(Cho et al. 2015). However, the commercial and sustainable
production of this bioproduct can be carried out when cultivated in low-cost substrates, such as organic and inorganic
waste (Cho et al. 2017).
Waste treatment is mediated by primary and secondary,
where the removal of solids occurs with the subsequent
bioremediation of organic and inorganic materials by
microorganisms. Microalgae appear as an alternative
approach to biological treatment and act as removers of
organic and inorganic fillers with subsequent conversion to
biomass, which can be exploited to obtain various bioproducts, such as biofuels (MohdUdaiyappan et al. 2017).
According to Pittman et al. (2011), Lundquist et al.
(2010), only cases involving the treatment of industrial
effluents with subsequent production of biofuel can generate
biodiesel at a competitive cost in the market; without this
process, it is economically unfeasible and does not offer a
positive return. Therefore, microalgae applied to wastewater
with subsequent generation of biodiesel can be considered a
sustainable and renewable production of bioproducts.
Based on a study with microalgae, Chisti (2007) observed
a regular life cycle and concluded that in 24 h, the lipid
capacity in the microalgae biomass varies between 20% and
50%, and with genetic engineering techniques, this time can
still be reduced. Mathimani et al. (2017) were successful in
testing the biodiesel harvested from microalgae mixed with
petroleum diesel, which obtained a reduction in the emission
of carbon monoxide and CO 2 from the engine.
110
R. R. Dias et al.
present a landscape of the use of microalgae for bioconversion of industrial wastes into biodiesel feedstocks.
2 Microalgae as a Biodiesel Feedstock
The overexploitation of energetic natural resources has driven the research and development (R&D) sector to seek
alternative sources of energy to supply the growing demand
and reduce the dependence on fossil fuels. Environmentally
friendly fuels that do not harm human health and the
ecosystems are the focus of researchers around the world
(Ingrao et al. 2018). In particular, the biodiesel with properties similar to diesel, a non-renewable fuel widely used by
trucks, buses and tractors, and other machines that require
high power, is gaining more and more space. It is worth
highlight that among the advantages of biodiesel using is the
significant reduction in the emission of polluting gases,
providing thus a high environmental gain (Cavalheiro et al.
2020).
The substitution of non-renewable fuels by renewable
ones reflects helpful contributions to the economy and
preservation of the environment. As sustainable and renewable alternative sources of energy have been full-blown the
biofuels of the first, second, third, and fourth generations. The
biodiesel generated from the oilseeds is named first generation, generated from the non-edible inputs of second generation, and generated from the organisms with elevated lipid
synthesis of third generation. The fourth-generation biodiesel
production uses microorganisms genetically modified and is
an emerging approach (Kumar et al. 2020).
Currently, biodiesel produced from food sources, through
the exploitation of vegetable oils and others that are from an
edible source, is already being applied directly to diesel
engines, or in parallel with fossil diesel (Ayoola et al. 2019).
However, the use of arable lands is one of the disadvantages
of using these sources. With the current concerns of international agencies, related to hunger and a significant growth
in the price of foods, new sources have been explored, as is
the example of oleaginous microorganisms, among them
microalgae. These microorganisms have high synthesis and
lipid storage in their cells (Severo et al. 2019).
The benefit of biodiesel fabrication from microalgae
includes the fast growth of cultures, high oil productivity,
and utilization of non-arable land (Maroneze et al. 2019). As
potential biological agents, these microorganisms can valorize wasted resources, mitigate carbon dioxide (CO 2 ), and
the biomass generated can be utilized for biodiesel production (Patidar and Mishra 2017).
3 Low-Cost Waste as Feedstock for Biodiesel
The use of alternative fuels to oil products is promising in
reducing the negative environmental impacts caused by the
consumption of fossil fuels. The excessive use of these
causes an increase in greenhouse gas emissions; thus, the
focus of the research has become the development of
renewable and environmentally friendly technologies that
serve as a commercially available energy source (Rajaeifar
et al. 2016).
Biodiesel is a promising biofuel to replace diesel (Oh
et al. 2012). The use of oleaginous microorganisms is an
option for biodiesel production. It offers advantages due to
its short cultivation period, higher productivity, and similarity in the fatty acid composition with the vegetable oils
generally used (Alptekin 2017; Cho and Park 2018).
Oilseed microorganisms accumulate a high concentration
of lipids in their cells, many times greater than 20%, and
using organic and inorganic carbon sources; the metabolism
is carried out (Xu et al. 2015; Amara et al. 2016). Unfortunately, the cost of cultivating these microorganisms is very
high, hampering the economic viability of microbial oils
(Cho et al. 2015). However, the commercial and sustainable
production of this bioproduct can be carried out when cultivated in low-cost substrates, such as organic and inorganic
waste (Cho et al. 2017).
Waste treatment is mediated by primary and secondary,
where the removal of solids occurs with the subsequent
bioremediation of organic and inorganic materials by
microorganisms. Microalgae appear as an alternative
approach to biological treatment and act as removers of
organic and inorganic fillers with subsequent conversion to
biomass, which can be exploited to obtain various bioproducts, such as biofuels (MohdUdaiyappan et al. 2017).
According to Pittman et al. (2011), Lundquist et al.
(2010), only cases involving the treatment of industrial
effluents with subsequent production of biofuel can generate
biodiesel at a competitive cost in the market; without this
process, it is economically unfeasible and does not offer a
positive return. Therefore, microalgae applied to wastewater
with subsequent generation of biodiesel can be considered a
sustainable and renewable production of bioproducts.
Based on a study with microalgae, Chisti (2007) observed
a regular life cycle and concluded that in 24 h, the lipid
capacity in the microalgae biomass varies between 20% and
50%, and with genetic engineering techniques, this time can
still be reduced. Mathimani et al. (2017) were successful in
testing the biodiesel harvested from microalgae mixed with
petroleum diesel, which obtained a reduction in the emission
of carbon monoxide and CO 2 from the engine.
110
R. R. Dias et al.