再生水紫外线-氯联合消毒工艺特性研究

以二级出水作为消毒对象,比较了紫外线-氯联合消毒与单一紫外线消毒对水中肠道指示菌的灭活效果,考察了联合消毒工艺副产物(三卤甲烷)生成情况.结果表明,单一紫外线消毒对肠道指示菌的灭活曲线在剂量大于10mJ/cm2时存在拖尾现象,剂量为80mJ/cm2时对总大肠菌群最高对数灭活率约为2.5;而在紫外线剂量20mJ/cm2、氯投加量8mg/L(接触时间30min)条件下,紫外线-氯联合消毒对总大肠菌群的对数灭活率达到7.0.20mJ/cm2紫外线与8mg/L氯消毒组合及80mJ/cm2紫外线与3mg/L氯消毒组合均可有效灭活总大肠菌群浓度至3CFU/L以下.经紫外线照射后再氯消毒,二级出水中三卤甲烷生成量仅为10~55mg/L.80mJ/cm2紫外线照射再氯消毒后三卤甲烷生成量略高于20mJ/cm2紫外线照射再氯消毒的情形.紫外线消毒后投加氯消毒,可有效提高再生水消毒效果,控制消毒副产物生成量.

Evaluation of sequential use of UV irradiation and chlorination to disinfect reclaimed water

The inactivation of coliforms in secondary effluent by UV irradiation alone and sequential use of UV irradiation and chlorination were investigated. The trihalomethane formation after the combination of treatments was also studied. The results showed that UV dose-inactivation curve tailed when UV dose was higher than 10mJ/cm2. The log inactivation ratio of total coliforms was about 2.5 as UV dose was 80mJ/cm2. Combination of 20 mJ/cm2UV irradiation and 8mg/L chlorination (30min contact time) achieved 7.0-log reduction of total coliforms. The survived total coliforms were less than 3CFU/L after the combination of 20mJ/cm2 UV irradiation and 8mg/L chlorination, or after the combination of 80mJ/cm2 UV irradiation and 3mg/L chlorination. Trihalomethane induced by chlorination was only 10-55mg/L after the combination of treatments. Trihalomethane concentrations were a little higher after 80mJ/cm2 UV irradiation than those after 20mJ/cm2 UV irradiation when the same chlorine dose was performed. Sequential use of UV irradiation and chlorination could improve the disinfection performance and control the disinfection by-product formation.