Microalgae-based biogas slurry treatment integrated with sustainable aviation fuel production: from waste to high-value bio-jet fuel

Anaerobic digestion (AD) effluent, or biogas slurry, contains high concentrations of nitrogen and phosphorus that require further treatment prior to discharge. Simultaneously, sustainable aviation fuel (SAF) production is limited by the availability of suitable lipid feedstocks. In this study, an integrated strategy combining biogas slurry remediation with microalgae-derived biofuel production was developed. Microalgal strains were screened from wastewater-associated environments based on their tolerance and nutrient removal performance in real biogas slurry. Among the isolates, Chlorella vulgaris exhibited superior adaptability and efficient removal of total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD). The harvested biomass was subsequently subjected to lipid extraction and catalytic hydrogenation to produce biodiesel and bio-aviation fuel. GC-MS analysis revealed that hydrotreated microalgae oil predominantly consisted of C16-C18 hydrocarbons, consistent with the compositional requirements of aviation fuels. Physicochemical characterization demonstrated that key fuel properties satisfy relevant ASTM specifications. The results confirm the feasibility of coupling wastewater treatment with high-value fuel production, enabling simultaneous pollutant removal, nutrient recovery, and biomass valorization. This work provides a sustainable waste-to-resource pathway, highlighting the potential of microalgae-based biorefineries for integrated environmental remediation and SAF feedstock generation.