Page 176 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Biorefinery of microalgae biomass 7

cultivated in wastewaters

1
1
Lizzette Moreno Garcı´a , Yvan Garie ´py , Simon Barnabe ´ 2
and Vijaya Raghavan 1
1
Department of Bioresource Engineering, McGill University, Montreal, QC, Canada,
2 Department of Chemistry, Biochemistry and Physics, Universite ´ du Que ´bec a `
Trois-Rivie `res, Trois-Rivie `res, QC, Canada

7.1 Introduction

3
The annual worldwide freshwater consumption in 2010 was estimated at 3928 km /
year. Of this, 56% will end up into wastewater in the form of municipal and indus-
trial effluents and agricultural drainage water, and 80% of this wastewater is
released to the environment with no or inadequate treatment (Koncagul et al., 2017).
Pollutants contained in wastewaters (nitrogen, phosphorus, and potassium) can further
accelerate the eutrophication of freshwater and increase groundwater pollution. These
pollutants are, indeed, among the main nutrients needed to grow algae.
Microalgae are photosynthetic prokaryotic or eukaryotic microorganisms with a
unicellular or simple multicellular structure and basic growth requirements. Their
rapid growth and ability to thrive in different environments are advantages that
make them more suitable than superior plants for the production of biofuel (Costa
and de Morais, 2014). Microalgae are highly adaptable to and tolerant of environmen-
tal stresses. They can be grown in various types of water resources, such as fresh and
marine water, as well as in agricultural, industrial, and municipal wastewaters.
The use of wastewaters as water and nutrient source to cultivate algae brings
along economic and environmental advantages. Phycoremediation of wastewaters
(a green technology using algae for water cleaning) can be a more efficient way of
wastewater treatment compared to conventional physical, chemical, and biological
processes. Moreover, wastewaters are a cheap and constant supply of nutrients for
microalgae cultivation.
Microalgae can be used to produce lipids, proteins, and carbohydrates that can
be further processed into biofuels and valuable coproducts with the capacity to
replace large volumes of crude oil (Nigam and Singh, 2011). One of the main hur-
dles that stand in front of microalgae biorefinery industrial plants is the easy access
to a constant supply of large amounts of water, energy, and quality nutrients. This
can be achieved by installing these biorefineries in colocation to sites where these
wastes are generated (Moreno-Garcia et al., 2017).
The feasibility of cultivating microalgae in different types of wastewaters to
simultaneously produce biomass and remove nutrients has been reported in several
Refining Biomass Residues for Sustainable Energy and Bioproducts. DOI: https://doi.org/10.1016/B978-0-12-818996-2.00007-7
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