Integrating Microalgae Cultivation With Municipal Wastewater Treatment for Biofuel Production: A Semiquantitative Review

ABSTRACT This study evaluates the efficiency of municipal wastewater (MW)–based microalgae cultivation for biofuel production and wastewater treatment using a meta‐analysis with random resampling and bias‐corrected adjustments. Integrated systems achieved mean removal rates of 87.7% for total nitrogen, 86.2% for ammonium, 84.8% for total phosphorus and 81.5% for phosphate, with lower efficiencies for chemical oxygen demand (64.2%) and nitrate (75.3%). Biodiesel conversion efficiencies ranged from 12.4% to 97.5%, averaging 59.2% (95% CI: [43.3, 73.1]), whereas lipid content varied from 2.7% to 61.7%, averaging 29.1% [26.0, 32.1]. Mixotrophic cultivation and pretreated MW performed best under optimal conditions (22°C–25°C, high nutrient availability, low metal concentrations), whereas stress conditions enhanced lipid accumulation. However, most studies remain laboratory‐scale, limiting real‐world applicability. Key scale‐up challenges include wastewater pretreatment, cultivation strategy, environmental stability, biomass harvesting and process integration. Addressing these challenges requires urgent full‐scale validation in operational wastewater treatment plants.