Tofu wastewater treatment through a combined process of coagulation-flocculation and ultrafiltration

Abstract

Wastewater from tofu industries contain many parameters such as total suspended solid (TSS), total dissolved solid (TDS), turbidity, and chemical oxygen demand (COD). These parameters are present in high amount and can endanger the aquatic environment and also decrease water quality. Several studies have been conducted to reduce these parameters, but still require a longer time which is around 12 to 78 days. This study aims to discuss the processes and methods to reduce TSS, TDS, turbidity, and COD parameters from tofu wastewater. The processes discussed in this study include a combined process of coagulation-flocculation and ultrafiltration (UF). The results of the study show that TSS, turbidity and COD reduced to 60%, 60% and 20%, respectively, in the coagulation-flocculation process, but TDS increased to around 90% because of the neutralization process using Sodium Hydroxide (NaOH) solution. Furthermore, it was shown that the combined process of coagulation-flocculation and UF was able to reduce TSS, turbidity, COD and TDS up to 99%, 99%, 75% and 50%, respectively. All the parameters contained in the water produced from the combined process of coagulation-flocculation and UF was in line with the National Environmental Quality Standard requirements, excluding COD due to the COD content in fresh tofu wastewater is very high.