In this research, tofu wastewater was treated using a combination of plasma electrolysis and coagulation-flocculation with a 1% chitosan solution as the coagulant. Untreated tofu wastewater is an organic waste with very high COD and TSS, 7771.3 mg/L and 840.5 mg/L, respectively. Coagulation-flocculation method was used for wastewater pretreatment because it could reduce the high pollution parameters in tofu wastewater while plasma electrolysis could reduce them to their smallest concentration. The best chitosan volume for reducing TSS to 74.4% was 20 mL, while the best volume for lowered COD to 16.8% was 40 mL. Plasma electrolysis was the next step for tofu wastewater degradation; it could drop the value of COD of tofu wastewater to 36% during a 60-minute process at 2000 mg/L as the initial concentration of the wastewater. This methodology reduced the environmental damage caused by the wastewater with an effective treatment.

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