Effect of Coagulant Dosage on Tofu Industry Wastewater Treatment in Combination with Ultrafiltration Process using Polysulfone Membrane

Abstract

Wastewater from tofu industry is one of water pollution sources that still require more effective treatment. This study aim to treat wastewater from tofu industry through a combination of coagulation-flocculation and ultrafiltration processes. Coagulation-flocculation is conducted prior to ultrafiltration process to minimize the effect of fouling on membrane and to improve the performance of ultrafiltration process. Poly aluminum chloride (PAC) was used as coagulant with doses of 100, 200, 300, 400 and 500 ppm. The wastewater feed have pH, total dissolved solid (TDS), total suspended solids (TSS), turbidity and chemical oxygen demand in the ranges of 3.8 - 4, 850 - 880 mg /L, 380 - 420 mg /L, 450-530 FAU and 5600 - 6600 mg /L, respectively. Experimental results showed that the effectiveness of coagulation increased with the addition of coagulant dose until the optimum dose is reached. After coagulation-flocculation process, COD, TSS, and turbidity decreased, whereas TDS increased. The optimum dose of the coagulationflocculation process was then used for a combination of coagulation-flocculation and ultrafiltration processes. The result of this combination process showed a decrease in COD, BOD, TSS, and turbidity.