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 CO2 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 CO2 utilization, thereby enabling absorbent regeneration in a closed-loop system. Utilizing packed absorption column-derived effluent (PACDE) containing KHCO3-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 % CO2 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 4505/L, operating expenses of IDR 1155/L, and profit gained of IDR 8991/L, yielding a net profit of IDR 3331/L. Mass balance assessment demonstrated valorization of carbon inputs with approximately 2.97 kg CO2 annually while generating 1175 L of lipid-rich microalgae oil and 3745 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.