Title page for ETD etd-11242009-020052
|Type of Document
||Ferreira, Francisco Cardoso
||Chlorine dioxide and by-products in water distribution systems
||Master of Science
|Gallagher, Daniel L.
|Dietrich, Andrea M.
|Hoehn, Robert C.
|Date of Defense
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,
chlori te 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 consti tuent has to be detected. However,
depending on the layout of each distribution system, small
variations can be observed.
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