Design and development of pilot photobioreactor for simultaneous microalgae cultivation and aquaculture wastewater treatment

This study presents an innovative and modular phototrophic biofilm photobioreactor (PBR) designed for the simultaneous cultivation of algae and the treatment of aquaculture wastewater (AWW). The vertical flat-plate BPR allows for stable microalgae growth while efficiently removing nutrients from wastewater under controlled conditions, including light, CO 2 , supplementation, water recirculation and continuous monitoring of parameters such as pH, nitrate (NO 3 - N) and phosphate (PO 4 3- P). The PBR was operated at an aquaculture facility using AWW, with nutrient removal and microalgal growth being monitored. The microalgae consortium composed of Chlorella sp. , Scenedesmus sp. and Phormidium sp. were evaluated for their growth potential and wastewater remediation capabilities. Results showed high nutrient removal efficiencies with 92 % reduction of PO 4 3- P (removal rate: 0.07 mg/L d) and a 62 % reduction of NO 3 - -N (removal rate: 1.1 mg/L d), bringing nutrient concentrations below the limits set by the Waters Protection Ordinance. Maximum biomass production reached a growth rate on land surface of 25 g/m 2 /d, with a favorable biochemical composition of 51 % proteins, 25 % carbohydrates and up to 8 % lipids, indicating the potential for use animal feed. This study demonstrates the feasibility of using AWW as a growth medium for microalgae while simultaneously achieving wastewater remediation, offering a sustainable solution for nutrient recycling in aquaculture operations. • Modular vertical flat-plate photobioreactor enables scalable and automated operation. • Production of high-quality microalgal biomass with a protein content up to 51 %. • High removal of nitrate and phosphate from aquaculture wastewater.