| Chlorine dioxide (ClO2) was compared with potassium permanganate (KMnO4) to determine which may be the better chemical for pretreatment of the Sioux Falls surface water source. Factors evaluated included impacts on taste and odor, removal of total organic carbon, coagulation, flocculation, sedimentation, oxidant demand, and THM production. The ClO2 decay and chlorite production kinetics were investigated, as was the removal of chlorite using ferrous iron.; Impacts of each chemical were determined using bench-scale experiments, such as jar tests and simulated distribution system tests. Tests were repeated during three seasons to simulate several possible river conditions.; The degradation of ClO2 was a rapid reaction that depended on water temperature. KMnO4 appeared to be the better preoxidant for taste and odor control. KMnO4 appeared to enhance flocculation, sedimentation, and filtration, but ClO2 appeared to have a minor effect on these processes. Reactions using ferrous iron were able to reduce chlorite to chloride. |
