The Combination of Coagulation-Flocculation and Membrane Processes to Minimize Pollution of Tofu Wastewater

Tofu is one of the most general foods consumed by Indonesian, but much wastewater are produced in the process of making this delicate food. This study aims to find the effectiveness of coagulation-flocculation process and membrane processes, especially ultrafiltration (UF) and reverse osmosis (RO) membrane, to treat tofu wastewater. The coagulant agent used is alum which has been tested to find its optimum dosage. The initial measurement of tofu wastewater had TSS, turbidity, COD and TDS ranging from 880 - 1009 mg/L, 901 - 1131 FAU, 5981 - 6525 mg/L and 2220 - 2640 mg/L, respectively, while the pH in the ranges of 4.0 to 4.2. The optimal dose of coagulant based on the experiments was 300 ppm. In the UF process, the concentration of all parameters except COD of produced water have already met the national standard. Furthermore, in the RO process, the produced water has already met the requirement of national standard for discharged water.