Algal-microbial community collaboration for energy recovery and nutrient remediation from wastewater in integrated photobioelectrochemical systems

Integration of algae and cyanobacteria with microbial fuel cell bioelectrochemical systems (BES) can significantly improve energy recovery and nutrient remediation in wastewater treatment. One innovative option is an integrated photobioelectrochemical system (IPB). Algae can contribute to BES function as an organic feedstock to support bacterial growth, by assisting anode bacteria to generate electricity, by providing oxygen from photosynthesis as a cathode electron acceptor, and by removing N and P from effluent water. However, critical interactions among bacteria-algae communities are poorly understood and practical questions such as light and pH conditions and taxa selection need more research to optimize microbial interactions and promote IPB function. Only a few ‘lab weed’ algal and cyanobacterial taxa have been tried in IPB systems but algae offer additional metabolic flexibility such as mixotrophy, to further process organic carbon, and nutrient hyperaccumulation, which have yet to be examined for potential in wastewater IPB treatment systems. This review aims to serve as a guide for wastewater bioenergy engineers to address challenges in IPB systems, and identifies a need for more collaboration between algal biologists and engineers to optimize algal-microbial community collaboration and work towards improved sustainability of wastewater treatment.