Treatment of Tofu industry's wastewater using combination of ozonation and hydrodynamic cavitations method with venturi injector

Indonesia is one of the country with the biggest population of tofu industries in the world. Tofu wastewater can harm the environment and alter the physical and chemical properties of water in river bodies, which is dangerous for human and living organism within the river. So it needs to be treated before disposed into the environment. The purpose of this research is to evaluate the performance of ozonation [O], hydrodynamic cavitations [HC], and combination of both [HC/O] in treating tofu wastewater. The variations of circulation flow rate are 2, 3, and 4 LPM and dosage of ozone is single and series ozonator. [HC/O] method (4 LPM flowrate and 129 mg/h dosage of ozone) produces the best performance, with degradation of 943 mg/L COD and 293 mg/L TSS in 180 minutes. This result is much better than the 4 LPM variant of [HC] method and series variant of [O] method separately, which are only capable of degrading 485 mg/L COD-288 mg/L TSS and 136 mg/L COD-233 mg/L TSS in 180 minutes accordingly.