Microalgae-Based Treatment of Winery Wastewater

Abstract Winery wastewater (WWW) is a high-strength effluent characterized by high organic load, nutrient content, and seasonal variability, posing significant environmental challenges. This review critically evaluates microalgae-based systems for WWW treatment, addressing their performance, scalability, and role within circular bioeconomy frameworks. Analysis of recent studies shows that microalgae-based systems can achieve high pollutant removal efficiencies, including up to ~ 90–92% chemical oxygen demand removal, high removal of total organic carbon and nitrogen (typically above 80%), and up to 91–95% ammonium removal. These systems also enable the production of biomass rich in proteins (up to ~ 58.8% dry weight) and valuable compounds such as pigments, supporting multiple valorization pathways. A key finding is that, despite strong technical performance, large-scale implementation remains limited. The main constraints are associated with wastewater variability, presence of inhibitory compounds, and operational challenges in biomass recovery, particularly energy-intensive harvesting and downstream processing. Techno-economic and life cycle analyses indicate that standalone systems are rarely economically viable under current conditions, and that feasibility depends on integration into multiproduct biorefineries and existing infrastructures. Regulatory uncertainty and the need for stakeholder acceptance further constrain deployment. Overall, microalgae-based WWW treatment represents a promising but system-dependent solution, requiring integrated technological, economic, and policy frameworks to achieve scalable implementation.