Municipal Wastewater Treatment by Microalgae with Simultaneous Resource Recovery: A Biorefinery Approach

Abstract

An increase in urbanization and industrialization has led to the increased discharge of wastewater, especially municipal wastewater, causing eutrophication as a large amount of wastewater is discharged into the water bodies without proper treatment. Current municipal wastewater treatment is carried out using the conventional activated sludge process (CAS), where indigenous microbial consortia with external aeration reduce organic matter. But critical issues are associated with the CAS process, including high energy requirements, generation of sludge, and emission of a large amount of carbon dioxide. Therefore, there is a need for alternative strategies in order to deal with these issues. Microalgae-based wastewater treatment process has emerged as a promising alternative technology for treating municipal wastewater. Microalgae offer certain advantages such as sequestration of atmospheric carbon dioxide, effective treatment of wastewater, and resource recovery in the form of microalgal biomass. The current chapter deals with the advancement made during these years for municipal wastewater treatment, including membrane technology, biofilm technology, and photo-sequencing batch reactors. There are also certain disadvantages associated with microalgae-based wastewater, such as scale-up, contamination in raceway ponds, and high energy requirements during the harvesting and dewatering process. In order to recover these costs, a biorefinery approach has been proposed where the microalgal biomass generated during the treatment process is transformed into various products such as biofuel, biochemical, and bioelectricity. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.