Standard jar tests and full-scale plant studies were conducted to evaluate the effectiveness of permanganate preoxidation as an aid to coagulation-flocculation of surface waters. The results of the Jar tests demonstrated that permanganate preoxidation obviously enhanced the coagulation-flocculation of the studied surface waters. Through full-scale plant studies, the positive effects of permanganate assistance in coagulation-flocculation of surface raters were confirmed by the turbidity reduction of about 4~11 FTU at permanganate dosages of 1~2 mg/L. It was observed that the size of flocs in the reaction tank became bigger if the water was preoxidized with permanganate, lowering the polyaluminium chloride (PAC) consumption by about 36%. In addition. the effectiveness of prechlorination and permanganate preoxidation on assisting in coagulation-flocculation were compared through full-scale studies at a water treatment plant using a shallow lake as its water source. showing that permanganate preoxidation was a more effective means to aid coagulation-flocculatlon.

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