The combined process of coagulation-flocculation and membrane separations to treat wastewater from tofu industry

Abstract

Wastewater from tofu industry needs an effective treatment in order to meet the water quality standards based on regulation of ministry of environment. This study carried out the treatment of wastewater from tofu industry using a combination of microfiltration (MF) and reverse osmosis (RO) processes. Coagulation-flocculation was conducted prior to MF to reduce the effect of fouling on membrane and improve its performance by removing the colloidal particles. Alum 300 ppm was used as the coagulant-agent for the coagulation-flocculation process. The wastewater feed has pH, total dissolved solid (TDS), total suspended solids (TSS), turbidity and chemical oxygen demand in the ranges of 4-5, 800-1500 mg/L, 800-1200 mg/L, 880-1100 FAU and 6000-8000 mg/L, respectively, which are far above the National Quality Standard. The produced water from the final treatment had the concentrations of TSS, turbidity, TDS and COD 0 mg/L, 0 FAU, 5 mg/L and 57.3 mg/L respectively, and this met the requirement from the National Environmental Quality Standard for the discharged wastewater.