Exploring Microbial Dynamics in a Pilot-Scale Microalage Raceway Fed with Urban Wastewater: Inisghts into the Effects of Operational Variables

Abstract

Microalgae-based wastewater treatment is a promising technology efficient for nutrient recycling and biomass production. Studies continuously optimize processes to reduce costs and increase productivity. However, changes in the operational conditions affect not only biomass productivity but the dynamics of the overall microbial community. This study characterizes a microalgae culture from an 80m² pilot-scale raceway reactor fed with untreated urban wastewater. Operational conditions such as pH, dissolved oxygen, and culture height were varied to assess microbial population changes. Results demonstrate that increased culture height significantly promotes higher microalgal and bacterial diversity. pH, dissolved oxygen and culture height highly affects nitrifying bacteria activity and nitrogen accumulation. Furthermore, the system exhibited high disinfection capability with average LRVs of 3.36 for E. coli and 2.57 for Clostridium perfringens. Finally, the fungi species detected included Chytridiomycota and Ascomycota, while purple photosynthetic bacteria were also found in significant abundance within the medium.

Keywords: Microalgae, Wastewater, Control Strategies, Bacteria, Fungi