Sustainable production of aviation biofuel using wastewater-grown microalgae: Process optimization and life cycle assessment of scenario-based strategies

초록

This study investigated the use of a locally isolated microalgae strain, Chlorella sorokiniana, obtained from municipal wastewater for sustainable aviation fuel (SAF) production and evaluated its environmental performance using life cycle assessment (LCA). Microalgae cultivated in wastewater achieved a biomass concentration of 0.825 g/L with enhanced lipid production, and the resulting bio-oil contained approximately 31% SAFequivalent components. Environmental impacts were assessed per 1 kg of dry biomass across five categories: global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), abiotic depletion potential (ADP), and ozone depletion potential (ODP).Five production scenarios were evaluated: Scenario 1 (AF6), using AF-6 medium; Scenario 2 (WW1), using municipal wastewater; Scenario 3 (WW2), incorporating intermittent aeration; Scenario 4 (WW3), applying an open drying system; and Scenario 5 (WW4), combining intermittent aeration and open drying. Using wastewater as the cultivation medium (Scenario 2) reduced environmental impacts compared with AF-6 medium, lowering GWP from 6.773 to 5.305 kg CO2eq. Intermittent aeration further reduced GWP to 5.104 kg CO2eq (25% lower than Scenario 1), while open drying decreased GWP by 14% and EP by more than 20%. The combined approach in Scenario 5 achieved the lowest impacts, with GWP of 4.318 kg CO2eq, EP of 1.501 & times; 10- 2 kg PO43- eq, and AP of 1.869 & times; 10- 2 kg SO2eq, along with an 18% reduction in ODP compared with Scenario 2. Cultivation aeration and biomass drying were identified as the primary environmental hotspots due to their high energy demand. Scenario 5 also showed the lowest net energy ratio (NER = 0.6591), indicating improved energy performance. These findings suggest that integrating microalgae cultivation with wastewater treatment plants (WWTPs) using intermittent aeration and open drying can provide a lower-impact and scalable pathway for SAF-oriented resource recovery.

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