Evaluating the Efficiency of Toman Fish (Channa micropeltes) Chitosan in Reducing COD and Other Pollutants in Tofu Wastewater

Wastewater from the tofu industry is a major source of environmental pollution in Indonesia due to its high organic content, which contributes to increased Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Suspended Solids (TSS), and turbidity. Many small-scale tofu producers do not have adequate wastewater treatment systems due to limited access to affordable and environmentally friendly technology. This study evaluated the effectiveness of chitosan extracted from snakehead fish (Channa micropeltes) as a natural coagulant to improve the physicochemical quality of tofu wastewater. Chitosan was produced from fish skin and scales through chemical deacetylation and applied at three doses (20, 24, and 28 mg/L). The parameters evaluated included COD, BOD₅, TSS, turbidity, and pH. The results showed that the application of chitosan reduced the COD and BOD levels at all doses tested, with COD showing a statistically significant difference between treatments (p < 0.05). A decrease in TSS was observed descriptively but was not statistically supported. Conversely, turbidity increased after chitosan addition, indicating the presence of fine suspended particles after the coagulation–flocculation process. The pH of the treated wastewater remained within the acidic range and did not approach neutral conditions. Overall, these findings indicate that chitosan derived from Channa micropeltes has potential as a natural coagulant for reducing organic pollution in tofu wastewater, particularly COD. However, additional treatment steps and optimization of operational conditions are required to address turbidity and pH adjustment. The utilization of fishery waste as a chitosan source also supports sustainable wastewater management and circular economy practices.