Algae for wastewater treatment and biofuel production

Abstract

Abstract Biofuels can be used for the provision of electricity, heating, and transport. Interest in biofuels has been sparked by their suitability to decrease carbon emissions and fossil fuel dependency without major modifications to our existing energy infrastructure. Microalgae grown in wastewater are a suitable feedstock to produce two of the most utilized types of biofuels: bioethanol and biodiesel. Biodiesel is obtained as fatty acid methyl esters from microalgae via a chemical reaction known as transesterification. Bioethanol is produced from biomass by microbial fermentation. So far, microalgae growing in wastewater has been characterized for containing a mixture of lipids, carbohydrates, and proteins. Hence, another area of interest is the use of wastewater-derived microalgae for the sequential production of bioethanol, biodiesel, and protein compounds. A biorefinery concept emerges for the generation of multiple co-products from the wastewater-derived microalgae that can maximize the use of unit operations and the valorization of microalgal biomass. In this chapter, concepts for biodiesel and bioethanol production are evaluated and a biocircular economy prospected.