This research highlights the potential of agro-industrial wastewater, especially from tofu production, for renewable energy and resource recovery using anaerobic digestion and biofilter-assisted ABR systems. These technologies generate biogas, volatile fatty acids, and acetic acid while producing nutrient-rich effluent that can be applied as organic fertilizer. The ABR biofilter system yields 310.49 L/day of biogas at an OLR of 2 kgCOD/m3·day, substituting 2.82% of firewood, 11.86% of LPG, and 33.39% of biopellets. On a national scale, with tofu and tempeh production of 400,000 tons, this substitution could reduce approximately 448,000 tons of CO2e emissions, demonstrating significant environmental benefits. Furthermore, the effluent meets the Indonesian organic fertilizer standard with nutrient concentrations of total N, P, Ca, Mg, Cu, and Fe.

 

Moreover, the high acetic acid content in tofu wastewater (92.40%) and tempeh wastewater (77.32%) can serve as a valuable source of acetic acid, which has significant economic potential and diverse applications in industries such as food production, pharmaceuticals, and volatile fatty acid (VFA).

 

The findings show that this low-cost, durable technology supports small enterprises and provides scalable solutions for policymakers and industries to promote sustainable, circular economy practices in wastewater management.