Sustainable lipid production from Chlorella vulgaris USU1 strain using packed absorption column-derived effluent as carbon source for biomass generation
Bambang Trisakti, Rivaldi Sidabutar, Irvan Irvan, Erman Munır, Maya Sarah, Farida Hanum, Mhd. Rivaldi Syahputra, Michael Michael, Vanness Vanness, Gloria Clarita Sinamo, Renata Ambarita, Mawardyah Sidauruk, Selvia Geraldine Silaban, Yasmin Nabilah, Hiroyuki Daimon, Mohd Sobri Takriff, Peer Mohamed Abdul
Abstract
The global surge in population and economic growth has intensified energy consumption reliant on fossil resources, leading to environmental degradation. Biogas, while offering a renewable alternative, requires CO 2 purification. This study addresses the critical knowledge gap in integrated waste-to-value approaches by investigating the synergistic coupling of biogas purification effluent utilization with Chlorella vulgaris USU1 cultivation for lipid production. This novel integration facilitates simultaneous high-quality biofuel generation and significant CO 2 utilization, thereby enabling absorbent regeneration in a closed-loop system. Utilizing packed absorption column-derived effluent (PACDE) containing KHCO 3 -PZCOO - complex solutions as the nutrient medium, this study systematically optimized cultivation parameters to maximize both biomass production and carbon utilization efficiency. Under optimized conditions (24:0 light intensity, 50-rpm agitation, 0.6 initial absorbance), the system achieved 58.3% CO 2 biofixation efficiency with a maximum biomass concentration of 8.64 g/L. Biochemical characterization revealed a composition of 23% carbohydrates and 56% proteins, with the fatty acid profile predominantly comprising palmitic (29.7%), oleic (27.6%), and linoleic (24.1%) acids. Notably, the USU1 strain demonstrated superior lipid accumulation capability with 31.19% yield, surpassing previously reported values for comparable strains. Economic analysis established favorable metrics with capital costs of IDR 4,505/L, operating expenses of IDR 1,155/L, and profit gained of IDR 8,991/L, yielding a net profit of IDR 3,331/L. Mass balance assessment demonstrated valorization of carbon inputs with approximately 2.97 kg CO 2 annually while generating 1,175 L of lipid-rich microalgae oil and 3,745 L of reusable biofertilizer effluent. This research establishes a foundation for scalable and closed-loop carbon capture and utilization technologies with implications for industrial zero-waste implementation and circular bioeconomy paradigms.