Exploiting brewery wastewater for the sustainable cultivation of Chlorella fusca: Biomass productivity, biochemical composition, and production cost

Abstract Beer is the fifth most consumed beverage worldwide, and its production demands large volumes of water, generating 3–10 L of effluent per liter of beer produced. This wastewater often requires municipal management, representing high operational costs and environmental concerns, particularly for microbreweries with limited infrastructure. The use of microalgae in brewery effluent offers a sustainable alternative for nutrient recovery, biomass generation, and integration into circular bioeconomy strategies. This study evaluated the growth performance and biochemical composition of Chlorella fusca LEB 111 cultivated in brewery effluent under semicontinuous operation, aiming to reduce production costs while maintaining biomass quality. Cultures were grown in 1.8-L photobioreactors with effluent concentrations of 25%, 50%, 75%, and 100%, compared to a BG-11 medium control. The 100% effluent assay achieved a biomass concentration of 0.77 g L⁻ 1 and productivity of 52.34 mg L⁻ 1 day⁻ 1 , with a balanced biochemical profile of 39.96% proteins, 31.64% carbohydrates, and 28.89% lipids. Notably, the highest protein content was obtained in EA75 during the first cycle (46.20%), the maximum carbohydrate accumulation occurred in EA75 during the second cycle (35.59%), and the highest lipid content was recorded in EA50 during the third cycle (40.61%). Cost analysis revealed a substantial reduction in biomass production expenses, from over €84 kg⁻ 1 in the control to €18 kg⁻ 1 in the undiluted effluent assay. These results advance knowledge on the adaptive biochemical responses of C. fusca under nutrient-limited wastewater conditions, providing a framework for sustainable algal cultivation and biomass valorization from nutrient-limited industrial effluents. Graphical Abstract