EFFECTS OF CONDITIONS OF TWO-STEP CHLORINATION ON TRICHLORAMINE FORMATION POTENTIAL

Abstract

 The effects of types of water (raw waters and waters after sedimentation-coagulation at water purification plants) and conditions of two-step chlorination on trichloramine formation potentials (NCl₃-FPs) were investigated. Like the cases of the pervious study, the effects of two-step chlorination were observed when ammonia was a main NCl₃ precursor in waters. The reduction of NCl₃-FP by two-step chlorination in both raw waters and waters after sedimentation-coagulation was shown and the difference was not observed for the reduction of NCl₃-FP by two-step chlorination. It was shown that several hours were required until second chlorine addition for NCl₃-FP control. As for pH (6-8) until second chlorine addition, pH 7 was the highest for NCl₃-FP control. The effects of two-step chlorination on trihalomethane (THM)-FP were low regardless of types of waters and chlorination conditions.