as: (i) use of microalgae to increase the nutritional value of food and animal feed
due to its chemical composition; (ii) extraction of high-value products from
microalgae that can be incorporation in cosmetic products; (iii) production of
biofuels; (iv) CO 2 capture; and (v) use of microalgae for the depuration of
wastewaters.
Gouveia and Empis (2003) concluded that biomass of C. vulgaris and H. pluvialis was a relatively concentrated natural source of carotenoids, which are natural
pigments that exhibit antioxidant capacity. The main carotenoids, found in
microalgae, with commercial interest are the b-carotene, lutein and astaxanthin
(Mostafa 2012). Besides these compounds, microalgae may be used for the production of biofuels and other bioproducts: proteins, cosmetics, pharmaceutical
products, among others.
In the context of environmental applications, microalgae may be used for
wastewater treatment in WWTPs (Hoffmann 1998; Oswald 2003). The discharge of
wastewaters with high amounts of N and P can cause severe eutrophication of
watercourses at downstream (Correll 1998). Thus, the removal of N and P based on
microalgae can be quite efficient, cheaper and ecologically safer than physical and
chemical treatments currently used (Hoffmann 1998).
Microalgae can also be used in biofixation of atmospheric CO 2 (or from
industrial gaseous effluents) through photosynthesis, thus contributing for the
reduction of this important greenhouse gas (Nascimento et al. 2015; Sheehan et al.
1998). Microalgae can capture about 1.7–2.4 tons of CO 2 per ton of biomass.
3 Wastewater Treatment by Microalgae
Microalgae can play an important role in the treatment of wastewater, particularly at
the level of nutrients removal and reduction of WWTPs operating costs.
3.1 Nutrient Removal
Urban wastewaters are rich in carbon, nitrogen, phosphorus and other minerals,
which have to be removed before effluent discharge in water bodies (Cabanelas
et al. 2013). An excess of organic carbon and nutrients released into rivers and lakes
can lead to decreased dissolved oxygen, toxicity of aquatic life and to
eutrophication.
In natural aquatic systems, microalgae assimilate large amounts of nutrients and
metals during their growth. Microalgae can digest inorganic sources of nitrogen
such as ammonium, nitrite and nitrate (Jia et al. 2016).
The use of microalgae in the wastewater treatment plant was first proposed by
Oswald and Gotass (1957) and in recent decades has received a lot of attention. The
premise of this approach is that the mixotrophic systems can be designed to reduce
3 Process Integration Applied to Microalgal Biofuels Production
43
due to its chemical composition; (ii) extraction of high-value products from
microalgae that can be incorporation in cosmetic products; (iii) production of
biofuels; (iv) CO 2 capture; and (v) use of microalgae for the depuration of
wastewaters.
Gouveia and Empis (2003) concluded that biomass of C. vulgaris and H. pluvialis was a relatively concentrated natural source of carotenoids, which are natural
pigments that exhibit antioxidant capacity. The main carotenoids, found in
microalgae, with commercial interest are the b-carotene, lutein and astaxanthin
(Mostafa 2012). Besides these compounds, microalgae may be used for the production of biofuels and other bioproducts: proteins, cosmetics, pharmaceutical
products, among others.
In the context of environmental applications, microalgae may be used for
wastewater treatment in WWTPs (Hoffmann 1998; Oswald 2003). The discharge of
wastewaters with high amounts of N and P can cause severe eutrophication of
watercourses at downstream (Correll 1998). Thus, the removal of N and P based on
microalgae can be quite efficient, cheaper and ecologically safer than physical and
chemical treatments currently used (Hoffmann 1998).
Microalgae can also be used in biofixation of atmospheric CO 2 (or from
industrial gaseous effluents) through photosynthesis, thus contributing for the
reduction of this important greenhouse gas (Nascimento et al. 2015; Sheehan et al.
1998). Microalgae can capture about 1.7–2.4 tons of CO 2 per ton of biomass.
3 Wastewater Treatment by Microalgae
Microalgae can play an important role in the treatment of wastewater, particularly at
the level of nutrients removal and reduction of WWTPs operating costs.
3.1 Nutrient Removal
Urban wastewaters are rich in carbon, nitrogen, phosphorus and other minerals,
which have to be removed before effluent discharge in water bodies (Cabanelas
et al. 2013). An excess of organic carbon and nutrients released into rivers and lakes
can lead to decreased dissolved oxygen, toxicity of aquatic life and to
eutrophication.
In natural aquatic systems, microalgae assimilate large amounts of nutrients and
metals during their growth. Microalgae can digest inorganic sources of nitrogen
such as ammonium, nitrite and nitrate (Jia et al. 2016).
The use of microalgae in the wastewater treatment plant was first proposed by
Oswald and Gotass (1957) and in recent decades has received a lot of attention. The
premise of this approach is that the mixotrophic systems can be designed to reduce
3 Process Integration Applied to Microalgal Biofuels Production
43