Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 168-177).

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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 145-150). Also available via the Internet.

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This project determined the thermodynamic potentials for various reactions between reduced manganese (Mn²), manganese oxide (MnO₂(s)), chlorine dioxide (Cl0₂), and potassium permanganate (KMnO₄). Based on these findings, laboratory analyses were performed to determine if these reactions would occur under simulated water treatment plant conditions. In addition, a speciation procedure was developed to quantify the various species of manganese and chlorine dioxide present in a single sample. The reactions and the speciation procedure were evaluated at TOC concentrations ranging from < 1.0 mg/L to 5.0 mg/L and at pH 6.0 and 8.0. The speciation procedure yielded a reliable measure of Mn², insoluble manganese, and Mn⁺⁷; however, the Mn⁺⁷ evaluation could be disrupted by the presence of free chlorine. The determination of Cl0₂ and Cl0₂- concentrations was also possible; however, the C10₂- concentration was subject to error. The laboratory analyses revealed that Cl0₂ was unable to oxidize either Mn² or MnO₂(s) to Mn⁺⁷ under any of the thermodynamically favored conditions. Both KMn0₄ and Cl0₂ selectively oxidized reduced organic material before reducing the concentration of Mn². When C10₂ and KMnO₄ were added simultaneously, the ClO2 reacted preferentially with the reduced materials. Only after the Cl0₂ concentration was exhausted did the MnO₂⁻ begin to oxidize the reduced species. / Master of Science

Chlorine dioxide is used as both a pre-oxidant and/or a post-disinfectant in several water treatment plants in the United States. Chlorine dioxide is associated with its byproducts chlorite and chlorate. Chlorine dioxide, chlorine, chlorite and chlorate were sampled in four distribution systems where chlorine dioxide is used for disinfection purposes: Charleston, WV, Columbus, GA, New Castle, PA, and Skagit, WA. The fate of chlorine dioxide and its by-products in distribution systems is discussed. A constituent transport model (TRAK) was applied to New Castle, PA distribution systems to assess times of travel. No relationship was found between the concentrations of chlorine, chlorine dioxide, chlorite and chlorate and the computed travel times. Water treatment plant and distribution system data received from Galveston, TX where the use chlorine dioxide has being tested is analyzed and discussed. Median chlorine dioxide concentrations are relatively constant in distribution systems with a value of approximately 0.2 mg/L; however, chlorine dioxide dosages applied at the treatment plant can induce different concentrations in the distribution system. Median chlorite concentrations in distribution systems range from 0.5 to 0.8 mg/L while median chlorate concentrations are generally lower in a range between 0.1 to 0.3 mg/L. The effects of distribution systems skeletonization in constituent transport modeling are also presented. Skeletonization does not affect significantly computed times of travel when the median percentage of constituent has to be detected. However, depending on the layout of each distribution system, small variations can be observed. / Master of Science

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