An Innovative Symbiotic Microalgae-IFAS Process for Nutrient Removal and Photo-oxygenation: Multiscale Investigations Using Microelectrodes and Next-generation Molecular Tools

A combination treatment of wastewater, utilizing the interaction of algae and bacteria, can offer lower energy consumption using photosynthetic aeration while also providing algal biomass for biofuel production. Here we demonstrate a successful algal-bacterial biofilm can assist in photoaeration for nitrification and algal driven direct denitrification without the need for additional carbon sources or mechanical aeration. Nutrient removal stabilized after 36 days with ammonia removal reaching 100% and 57% for the Microalgae Integrated Fixed Film Activated Sludge (MAIFAS) and suspended reactors, respectively, while MAIFAS and suspended reactors removed 51 and 49% of the phosphorous, respectively. Furthermore, the algae bacteria consortia showed excellent settling with an sludge volume index (SVI) ranging from 74 to 111 and less than 1 mg/L Chl. α in the effluent. Overall this research shows the feasibility of a microalgaebased IFAS wastewater treatment process for reducing energy cost for aeration while meeting stringent effluent standards.