Enhanced coagulation with composite permanganate pretreatment in polluted water treatment

Full-scale tests have been conducted for enhanced coagulation in stabilized surface waters with low turbidity, high organic content and low temperature by PAC coagulation combined with composite permanganate (CP) pretreatment, KMnO₄ preoxidation and prechlorination processes. The values of turbidity, COD, bacteria, coliform, TMn, chloroform and chloroform potential by different processes were observed. Test results show that CP pretreatment enhanced coagulation is superior to prechlorination and KMnO₄ preoxidation. This pretreatment process has the capability to reduce the above parameter values sharply with less coagulant compared to prechlorination. CP pretreatment will not increase chloroform in water and can effectively remove chloroform potential. The manganese dioxide produced during permanganate preoxidation also enhanced coagulation, which has special adsorption and oxidation for the organic matter, and at the same time it acts as catalyst to accelerate the reaction between the KMnO₄ and organics in water. CP enhanced coagulation is a cost-effective and most efficient pretreatment process.