自来水常规和深度处理工艺中挥发性有机物的变化规律

Occurrence and Distribution of Volatile Organic Compounds in Conventional and Advanced Drinking Water Treatment Processes

针对连云港市3个自来水厂不同的消毒处理工艺，研究了常规和深度处理对原水中挥发性有机物（VOCs）的处理效果和工艺过程中VOCs的形成规律．在所采集的水样中，67种目标VOCs有3类共30种被检出，其中羰基化合物、卤代烃和苯系物的检出浓度范围分别是0．04～61．27、0．02～35．61和0．07～2．33μg·L^-1．研究表明，常规氯消毒工艺能有效去除原水中的苯系物类化合物，但会产生三卤甲烷（THMs）等消毒副产物；臭氧一生物活性炭深度处理工艺能有效降低预氯化过程中THMs的生成量，但会产生如羰基化合物等风险污染物．管网中深度处理产生的羰基化合物在余氯作用下转化形成THMs．管网水中检出的VOCs除巴豆醛的致癌风险在9．3×10^-5～2．2×10^-4之间，略高于USEPA的控制阈值（10^-6～10^-4）外，其他化合物的健康风险都处于较低水平．

A series of experiments were conducted to study the occurrence and distribution of volatile organic compounds （VOCs） in conventional and advanced drinking water treatment processes of 3 water treatment plants in Lianyungang City. Results showed that 30 compounds of 3 classes were detected from 67 kinds of VOCs in all the samples collected. The concentrations of carbonyl compounds, halogenated hydrocarbons and benzenes detected were in the ranges of 0.04- 61.27, 0.02- 35.61 and 0.07- 2.33 μg·L^-1 , respectively. Comparing the changes of different VOCs in three drinking water treatment plants, conventional chlorination process could effectively remove benzenes but meanwhile produced trihalomethanes （THMs）. Additional advanced treatment ozonation-biological activated carbon process could decrease the formation of THMs during pre-chlorination but produced new risky contaminants like carbonyl compounds. The changes of VOCs in tap water were also investigated. It was found that carbonyl compounds produced by ozonation could be further transformed to THMs with residual chlorine. However, the health risks of all detected compounds in tap water were at a low level, except that the carcinogenic risk of crotonaldehydes （9.3 ×10^-5-2.2×10^-4） was slightly higher than the US EPA threshold （10^-6-10^-4）.