Process Integration Applied to Microalgal Biofuels Production

The rapid development of modern society has resulted in an increased demand for energy and, consequently, an increased use of fossil fuel reserves, compromising the energy sector sustainability. Moreover, the use of this source of energy led to the accumulation of greenhouse gases (GHGs) in atmosphere, which are associated with climate change. In this context, European Union has established new directives regarding GHG emissions and the renewable energy use. Microalgae may have an important role in the achievement of these goals. These photosynthetic microorganisms have a high growth rate, are able to capture CO2, the biomass can be used to produce biofuels, constituting an undeniable economic potential. Microalgae may also be a source of low carbon fuel, being one of the most studied biofuels feedstock. They are considered a sustainable energy resource, able to reduce sig- nificantly the dependence on fossil fuel. They can grow on places that are unsuitable for agriculture, not competing with land for food production. The use of wastewater as microalgal culture medium will reduce the required amount of freshwater and nutrients, achieving simultaneously an effluent with low nutrient concentrations. An important step to increase the competitiveness (promoting simultaneously the environmental sustainability) of microalgal biofuels regarding fossil fuels is the optimization of culture parameters using wastewater as culture medium. Thus, this chapter aims to present the recent studies regarding the integration of wastewater treatment and microalgal cultivation for biomass/biofuel production.