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This powerpoint presentation begins by providing a brief overview of drinking water disinfection and emerging challenges for water treatment. Ultraviolet (UV) irradiation is presented as a promisingalternative, along with photolysis of chlorine, the role of bromide during UV/chlorineprocess, and concerns for halate formation duringUV/chlorine process. Study objectives were to: explore the effects of bromide ion on the photolysisof free chlorine; characterize halate formation during UV/chlorinecoexposure process with the presence of bromide; and, evaluate contamination level of halate in simulated drinking water after UV/chlorine process. Materials and methods included: natural organic matter (NOM) source - Suwannee River NOM (SNOM solution); free halogen source - NaOCl: Clsub2/sub(gas) + 0.01M NaOH. UV system configuration is presented, along with analytical methods. Conclusions indicate that: the presence of bromide did not significantly changethe observed photolysis free chlorine; upon UVirradiation, chlorine is always far more efficient inachieving higher [OH]subSS/sub than bromine;BrO and BrOsub2/subsup-/sup may serve as decisive intermediatesduring bromate formation; the scavenging of BrOsub2/subsup-/supby excessive free chlorine could hinder the bromateformation from OH-dominated multistep oxidation; and, from a practical point of view, when the bromide ionconcentration in raw water exceeding 1 mg/L, theUV/chlorine process may induce the potential risk ofbromate exposure by breaking its MCL of 10 g/L;on the other hand, the chlorate formation was minorconsidering the provisional guideline value of 700g/L. Includes figures.

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Edition: Vol. - No. Published: 11/01/2009 Number of Pages: 29File Size: 1 file , 1.3 MB