Microalgae for brewery wastewater treatment and biomass valorization: a systematic review

The brewing industry, a major contributor to global wastewater production, generates wastewater rich in organic matter and nutrients. This presents both an environmental challenge and an opportunity for biotechnological innovation. This systematic literature review explores the potential of microalgae in the treatment of brewery effluents and the production of high-value bioproducts. Nine peer-reviewed studies published between 2017 and 2023 were analyzed, focusing on micro-algal species, cultivation strategies, treatment efficacy, and biomass applications. Chlorella and Scenedesmus emerged as the most effective genera, achieving chemical oxygen demand (COD) removal rates of up to 88.52% and demonstrating strong biomass productivity. Co-cultivation with bacteria enhanced pollutant removal and lipid accumulation, underscoring the synergy between microalgae and native microbiota. The biomass derived from brewery effluent treatment was found to be rich in carbohydrates, lipids, and proteins, supporting its use in biofuel and biofertilizer production. Despite promising results, industrial-scale implementation remains constrained by variability in effluent composition and the need for standardized processes. The findings emphasize the dual environmental and economic benefits of integrating micro-algal systems into brewery wastewater management and highlight the untapped potential for bioproduct development in line with circular bioeconomy principles.