Mayige, Christopher Ngelya creator Samorn Muttamara Chairperson Vigneswaran, Saravanamuthu Examination Committee Harada, Hideki Examination Committee Danish International Development Agency, Denmark Scholarship Donor text series technical report th Bangkok Asian Institute of Technology 1990 continuing eng 57 p. This stud y investigated the occurrence of reaction products with public health significance when chlorine dioxide disinfection is adopted in place of the current chlorination at Bangkhen Water Treatment Plant . An earlier study at the plant (GHAZALI,1989) h ad revealed a threat to public health in the future from continued chlorination due to the formation of excessive amounts of trihalomethanes (THMs ) in drinking water. The THMs, arise from t h e reaction of chlorine with a variety of organic compounds present in the water a nd, have toxic effects. The present study involved monitoring the resulting levels o f THMs, chlorates , chlorites a nd residual chlorine dioxide in the untreated water and after adding the disinfectant. Chlorine dioxide doses of 1 to 10mg/L were applied to filtered unchlorinated water from Bangkhen Water Treatment Plant. The organic content of t h e water was on average about 2.4mg/L , as the total organic carbon (TOC ) . The trihalomethanes (THMs ) were measured by the head space - gas chromatographic method. Chlorine dioxide residuals were monitored with the simple iodometric method . Chlorates and chlorites were quantified u sing iodometric titrations while varying the pH in a de-aerated medium. Neither bromine nor THMs were found in t he filtered water from the treatment plant . After application of chlorine dioxide dioxide, no THMs were detected in t h e treated water . Very l ow levels of chlorites and chlorates ( 0.1mg/L) were observed in t he finished water even after 48 hours of contact after the dosing of chlorine dioxide in excess of 10mg/L. The stability of the chlorine dioxide was evident from the observed ( - 0 .lmg/L) residuals at the end of 48 h ours contact time. From t h is study it can b e seen that chlorine dioxide at doses of 1mg/L to 1 .2mg/L constitutes a viable alternative for Bangkhen Water Treatment Plant to the present chlorination for curbing THMs and adequate disinfection of t h e water. A Thesis submitted in partial requirements for the degree of fulfillment Master of of the Science, School of Environment, Resources and Development Thesis (M.Sc.) - Asian Institute of Technology, 1990 Water Purification Disinfection and disinfectants Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B18366 http://203.159.5.9/ait-thesis/detail.php?q=B18366 150399 20260818144318.0