03126cas|a2200253 i 450000500170000000800410001703500150005810000310007324500630010426000520016730000100021949000270022950001540025650200570041052020110046765000240247865000350250270000350253770000560257270000440262871000760267281000590274885600650280720260818144318.0150399s1990    th  uzm rtt  00|  a1eng d  a.b103795021 aMayige, Christopher Ngelya10aInvestigation of ClO2 disinfection at Bangkhen Water Works  aBangkok :bAsian Institute of Technology,c1990  a57 p.1 aThesis ;vno. EV-90-13  aA Thesis submitted in partial  requirements for the degree of  fulfillment Master of of the Science, School of Environment, Resources and Development  aThesis (M.Sc.) - Asian Institute of Technology, 1990  aThis 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.  0aWaterxPurification 0aDisinfection and disinfectants0 aSamorn Muttamara,eChairperson1 aVigneswaran, Saravanamuthu, eExamination Committee1 aHarada, Hideki, eExamination Committee2 aDanish International Development Agency,  Denmark., eScholarship Donor2 aAsian Institute of Technology.tThesis ;vno. EV-90-13  3Full-Textuhttp://203.159.5.9/ait-thesis/detail.php?q=B18366