Study on treatment of black and odorous water by KMnO₄ pre-oxidation enhanced coagulation process

The removal effect of organic pollutants in black and odorous water by KMnO₄ pre-oxidation combined with conventional coagulating sedimentation treatment processes was studied. The flocculation performance of various coagulant flocculation treatment was analyzed, and the removal effects of COD_Cr, UV₂₅₄ and turbidity before and after adding potassium permanganate compared and analyzed. The test results showed that KMnO₄ pre-oxidation technology could strengthen the poly ferric magnesium silicate (PFMS) coagulating sedimentation process to remove organic pollutants. In the entire dosage range of the coagulation test, the PFMS coagulant had a great effect on the black and odorous water turbidity. The removal rate of turbidity was much higher than that of poly aluminum chloride and ferric chloride coagulants. The results of SEM characterization showed that the PFMS was aggregated in a tree-like shape, which could enhance the functions of adsorption bridging and net replenishment in the coagulation process. When the pH of raw water was 8, the dosage of KMnO₄ was 25 mg/L, and the pre-oxidation time was 25 minutes, the highest COD_Cr removal rate of 81.76% could be reached, which was 12.15 percent higher than the single coagulating sedimentation process, while the highest UV₂₅₄ removal rate was 49.44%, increased by 11.71 percent compared with the single coagulating sedimentation. The turbidity removal rate of black and odorous water before and after adding KMnO₄ was both above 90%.