Quek P H, Hu J Y, Chu X N, Feng Y Y, Tan X L
Centre for Water Research, Department of Civil Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore.
Water Sci Technol. 2006;53(6):123-9. doi: 10.2166/wst.2006.184.
Ultraviolet (UV) disinfection is becoming increasingly popular as an alternative disinfection technology to chlorination in recent years. In this study, we investigated the photoreactivation of Escherichia coli following medium-pressure (MP) UV disinfection of synthetic water by a bench-scale collimated beam apparatus. The UV doses ranged from 1.6 -19.7 mWs/cm2 and photoreactivation was investigated for 6 hours under fluorescent light. In addition, chloramination was applied after UV disinfection to investigate its ability to control photoreactivation. It was found that photoreactivation occurred for all UV doses tested and the increase in bacteria numbers ranged from 0.04 to 1.35 log10. However, the degree of photoreactivation decreased with increased UV doses. Chloramination experiments revealed that the addition of 0.5 mg/l of monochloramine resulted in suppression of photoreactivation for 1 hour only. An increased monochloramine dose of 1 mg/l was found to prevent photoreactivation for the entire duration of the experiment. The results of this study have shown that photoreactivation occurs even after MP UV disinfection, although it is of a lesser extent at higher UV doses. This study has also established that secondary chloramination can effectively suppress and eliminate photoreactivation with a chloramine dose of 1 mg/l.
近年来，紫外线（UV）消毒作为一种替代氯化消毒的技术越来越受欢迎。在本研究中，我们使用台式准直光束装置，研究了合成水中大肠杆菌经中压（MP）紫外线消毒后的光复活情况。紫外线剂量范围为1.6 - 19.7 mWs/cm2，并在荧光灯下对光复活进行了6小时的研究。此外，在紫外线消毒后进行氯胺化处理，以研究其控制光复活的能力。结果发现，在所测试的所有紫外线剂量下均发生了光复活，细菌数量增加范围为0.04至1.35 log10。然而，光复活程度随着紫外线剂量的增加而降低。氯胺化实验表明，添加0.5 mg/l的一氯胺仅能在1小时内抑制光复活。发现将一氯胺剂量增加到1 mg/l可在整个实验期间防止光复活。本研究结果表明，即使经过中压紫外线消毒后仍会发生光复活，尽管在较高紫外线剂量下程度较小。本研究还确定，二次氯胺化可以用1 mg/l的氯胺剂量有效抑制和消除光复活。
