Algae-Based Tertiary Treatment of Secondary Municipal Effluent for Simultaneous Nutrient Recovery and Biomass Production

Abstract

The increasing demand for sustainable wastewater treatment technologies has encouraged the development of resource recovery approaches capable of improving effluent quality while generating value-added products. This study investigates algae-based tertiary treatment of secondary municipal effluent for simultaneous nutrient removal, nutrient recovery, and biomass production under controlled cultivation conditions. The research focuses on evaluating the efficiency of algal systems in removing nitrogen and phosphorus while producing biomass suitable for bioenergy and bioproduct applications. Experimental analyses were conducted to examine the influence of hydraulic retention time, light intensity, carbon dioxide supply, pH, temperature, and nutrient loading on algal growth performance and wastewater treatment efficiency. Results demonstrated that algal cultivation effectively reduced nutrient concentrations in secondary municipal effluent through biological uptake and assimilation mechanisms. Significant removal of ammoniacal nitrogen and phosphate was achieved alongside enhanced dissolved oxygen generation and improved effluent quality. The produced algal biomass exhibited substantial organic content suitable for downstream applications such as biofuel production, fertilizer generation, and bioproduct synthesis. Kinetic evaluation revealed that nutrient uptake and biomass productivity are strongly influenced by environmental conditions and algal metabolic activity. The integrated treatment system also contributed to reduced sludge generation and lower energy demand compared with conventional tertiary treatment methods. Comparative assessment confirmed that algae-based processes offer environmental and economic advantages through simultaneous wastewater polishing and resource recovery. Furthermore, the utilization of municipal effluent as a cultivation medium supports circular economy strategies and sustainable water management practices. The findings highlight the potential of algae-based tertiary treatment as an efficient and eco-friendly technology for advanced municipal wastewater treatment and biomass valorization applications.