Life cycle assessment of integrated microalgae oil production in Bojongsoang Wastewater Treatment Plant, Indonesia

This study aims to determine the eco-friendliness of microalgae-based renewable energy production in several scenarios based on life cycle assessment (LCA). The LCA provides critical data for sustainable decision-making and energy requirement analysis, including net energy ratio (NER) and cumulative energy demand (CED). The Centrum voor Milieuwetenschappen Leiden (CML) IA-Baseline was used on environmental impact assessment method by SimaPro v9.3.0.3® software and energy analysis of biofuel production using native polyculture microalgae biomass in municipal wastewater treatment plants (WWTP) Bojongsoang, Bandung, Indonesia. The study was analyzed under three scenarios: (1) the current scenario; (2) the algae scenario without waste heat and carbon dioxide (CO 2 ); and (3) the algae scenario with waste heat and carbon dioxide (CO 2 ). Waste heat and CO 2 were obtained from an industrial zone near the WWTP. The results disclosed that the microalgae scenario with waste heat and CO 2 utilization is the most promising scenario with the lowest environmental impact (− 0.139 kg CO 2 eq/MJ), positive energy balance of 1.23 MJ/m 3 wastewater (NER > 1), and lower CED value across various impact categories. It indicates that utilizing the waste heat and CO 2 has a positive impact on energy efficiency. Based on the environmental impact, NER and CED values, this study suggests that the microalgae scenario with waste heat and CO 2 is more feasible and sustainable to adopt and could be implemented at the Bojongsoang WWTP.