Agro-Industrial Wastewaters as Feedstocks for Microbial Lipase Production: Integrating Enzyme Bioprocessing, Effluent Valorization and Wastewater Management

Agro-industrial wastewaters contain substantial organic and lipid loads that pose environmental challenges but may also provide potentially low-cost substrates for microbial bioprocessing. This scoping review evaluated the use of agro-industrial wastewaters as fermentation feedstocks for microbial lipase production and their potential integration with wastewater treatment and resource recovery. Previous reviews have largely treated microbial lipase production, waste-derived fermentation substrates, and lipase-based wastewater treatment as separate topics. This review bridges these areas by focusing on liquid agro-industrial wastewaters as fermentation feedstocks and jointly evaluating lipase production, changes in wastewater quality, process conditions, analytical comparability, and technological readiness. Following PRISMA-ScR guidance, Scopus and the Web of Science were searched for studies published from 2016 to 2026, yielding 20 eligible articles. The evidence was heavily concentrated on olive mill wastewater and palm oil mill effluent, whereas other agro-industrial effluents were scarcely investigated. Yeasts, bacteria, filamentous fungi, mixed cultures, and recombinant whole-cell systems were employed, although cultivation strategies, wastewater conditioning, supplementation, and lipase assays varied substantially. Several studies combined lipase production with reductions in chemical oxygen demand, oil and grease, phenolic compounds, or other wastewater constituents. However, most processes remained at the shake-flask scale, while downstream recovery, detailed enzyme characterization, storage stability, catalyst reuse, and controlled scale-up were infrequently investigated. Wastewater-based lipase production therefore represents a promising circular-bioeconomy strategy, but further development requires standardized performance reporting, minimal-input cultivation, integrated final-effluent assessment, scale-up, and formal techno-economic and life-cycle assessment.