Abstract
One of the foods favorites by Indonesian people is tofu. In the process of making tofu, it produces wastewater. The tofu wastewater must be treated first to reduce environmental pollution. To treat the liquid waste, it is using biological treatment by an anaerobic baffled reactor with bio-ball. The purpose of this study was to determine the optimum time at 75% tofu wastewater concentration. The detention time used in this study was 12 hours, 24 hours, 36 hours and 48 hours. Seeding takes time about 45 days, with the obtained VSS was 5550 mg/L. Furthermore, acclimatization in the reactor takes about 30 days, with an efficiency of removing COD of 86.3%. The results obtained that at 12 hours of detention, there is a COD allowance of 79.8%, 24 hours of detention time there is a COD allowance of 85.4%, 36 hours of detention time 86.3%, and 48 hours of detention time 88.4 %. It shows that the optimum detention time in this anaerobic reactor is 48 hours. However, the COD level was 765.3 mg/L is still slightly above the quality standard according to the Minister of Environment Regulation No.5 2014, which is the maximum COD level of 300 mg/L.