Continuous-flow integrated mangosteen peel adsorption and ultrafiltration membrane treatment for organic pollutant removal from tofu wastewater

The rapid expansion of the tofu industry in Indonesia generates substantial volumes of wastewater characterized by high biochemical oxygen demand (BOD), chemical oxygen demand (COD), and acidic pH, posing significant environmental risks when discharged without adequate treatment. To address these challenges, this study evaluates a continuous-flow integrated treatment system combining adsorption using KOH-activated mangosteen ( Garcinia mangostana ) peel with ultrafiltration membrane technology. The adsorbent was synthesized through chemical activation followed by carbonization at 300 °C. Treatment performance was assessed at varying adsorbent masses (60, 80, 100, 120, and 140 g) and flow rates (2 and 4 L min⁻¹). The optimal condition, using 120 g of adsorbent at a flow rate of 2 L min⁻¹, achieved reductions of 67.45% in BOD and 88.45% in COD. The treated effluent remained acidic, indicating that the integrated treatment system provided limited pH improvement under the tested conditions. Overall, the continuous-flow integration of KOH-activated mangosteen peel adsorption and ultrafiltration membrane technology demonstrated potential for organic pollutant removal from tofu wastewater. However, additional treatment steps or process modifications are required to improve pH correction and meet discharge standards.