Full Description

Empirical models for chlorine dissipation in drinking water distribution systems havebeen developed as a function of pipe material and water quality. Polyvinyl chloride (PVC), galvanized steel,unlined cast iron and lined ductile iron pipes were taken from actual distribution systemsand used to build eighteen pilot distribution systems (PDSs), which received finishedwater. Operation of the pilot distribution systems simulated normal operationcircumstances. Hydraulic retention time was regulated using pumps to 5 days. Freechlorine and monochloramines were used in the study. The PDSs were monitored fortime, temperature, pH, and total organic carbon. Separate models for free and totalchlorine decay were developed.First-order kinetic models accurately described free and combined chlorine decay. Rateconstants were dependent on pipe material, UV-254 and temperature. Rate constantswere developed by material and free and total chlorine using non-linear regression. Freeand combined chlorine decay was similar in PVC and lined ductile iron pipes, and wassignificantly less rapid than in galvanized and unlined cast iron pipes. Hence, surfacereactions with the aqueous phase disinfectant were more significant than disinfectantreactions with the aqueous phase solutes. Sensitivity analyses indicated that disinfectantresiduals required by regulation were difficult to achieve in summertime conditions forunlined metallic pipes. Includes 14 references, tables, figures.

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Edition: Vol. - No. Published: 06/17/2004 Number of Pages: 20 File Size: 1 file , 1.7 MB