UV/O_3工艺去除甲基叔丁基醚过程中BrO-3^-的产生与控制

Bromate formation and control in process of removing methyl tert-butyl ether by UV/O_3 technology

引言臭氧用于饮用水处理已有悠久的历史,可有效去除色度和浊度,除异味,降解有机污染物和提高可生物降解性能。由于臭氧在紫外的激发下产生氧化能力更强的羟基自由基（·OH）,该氧化剂与许多物质的反应速率常数在108～1010之间,因此,臭氧与紫外的联合作用能够迅速降解多种持久性有机物。面对水源地中出现的种类繁多的持久性有机物,UV/O3工艺受到了越来越多的关注。

Bromate is a potential carcinogen and formed in treatment of bromide-containing water using ozone-based technologies.So,the study on bromate formation during removal of organic pollutions is necessary for applying UV/O3 process.The effects of water background,initial MTBE concentration,ozone dosage and dosing method on removal of methyl tert-butyl ether（MTBE）and formation of bromate were studied.Besides,the mechanism of action for ozone dosing method was explored.The results showed that MTBE removal rates obtained by UV/O3 process in ultrapure water and tap water were 93.5% and 88.67%,and bromate concentration were 18.01 μg·L-1 and 12.13 μg·L-1,respectively,which were higher than the standard value of 10 μg·L-1.The promotion of initial MTBE concentration inhibited bromate formation,but longer reaction time were compulsory since MTBE concentration was required to be lower than proposed concentration of 5 μg·L-1.In this case,bromate formation was eventually enhanced.Increase of ozone dosage was favorable for MTBE removal,but caused decline of the utilization rate of ozone and the promotion of bromate formation.Comparing three ozone dosing methods in which the same ozone dosage of 5 mg·min·L-1 was applied,the highest hydroxyl radical（·OH）exposure and minimum ozone exposure were obtained in the method at ozone concentration of 0.75 mg·L-1 and reaction time of 120 min.Therefore,the concentrations of MTBE and bromate in water both met the standard values after treatment.