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 promising
alternative, along with photolysis of chlorine, the role of bromide during UV/chlorine
process, and concerns for halate formation during
UV/chlorine process. Study objectives were to: explore the effects of bromide ion on the photolysis
of free chlorine; characterize halate formation during UV/chlorine
coexposure 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: Cl<sub>2</sub>(gas) + 0.01M NaOH. UV system configuration is presented, along with analytical methods. Conclusions indicate that: the presence of bromide did not significantly change
the observed photolysis free chlorine; upon UV
irradiation, chlorine is always far more efficient in
achieving higher [OH]<sub>SS</sub> than bromine;
BrO• and BrO<sub>2</sub><sup>-</sup> may serve as decisive intermediates
during bromate formation; the scavenging of BrO<sub>2</sub><sup>-</sup>
by excessive free chlorine could hinder the bromate
formation from •OH-dominated multistep oxidation; and, from a practical point of view, when the bromide ion
concentration in raw water exceeding 1 mg/L, the
UV/chlorine process may induce the potential risk of
bromate exposure by breaking its MCL of 10 µg/L;
on the other hand, the chlorate formation was minor
considering the provisional guideline value of 700
µg/L. Includes figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.3 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 29 |
| Published : | 11/01/2009 |
