Two-step chlorination: A new approach to disinfection of a primary sewage effluent

WATER RESEARCH

卷:108

Article

Li, Yu¹  Yang, Mengting^1,2  Zhang, Xiangru¹  Jiang, Jingyi¹  Liu, Jiaqi¹  Yau, Cie Fu¹  Graham, Nigel J. D.³  Li, Xiaoyan⁴ 

[1] Hong Kong Univ Sci & Technol, Dept Civil & Environm Engn, Hong Kong, Hong Kong, Peoples R China

[2] Shenzhen Univ, Coll Chem & Environm Engn, Shenzhen 518060, Hong Kong, Peoples R China

[3] Imperial Coll London, Dept Civil & Environm Engn, London, England

[4] Univ Hong Kong, Dept Civil Engn, Hong Kong, Hong Kong, Peoples R China

关键词: Disinfection;    Two-step chlorination;    Disinfection efficiency;    Synergistic effect;    DBPs;   

DOI  :  10.1016/j.watres.2016.11.019

来源: Elsevier

【 摘 要 】

Sewage disinfection aims at inactivating pathogenic microorganisms and preventing the transmission of waterborne diseases. Chlorination is extensively applied for disinfecting sewage effluents. The objective of achieving a disinfection goal and reducing disinfectant consumption and operational costs remains a challenge in sewage treatment. In this study, we have demonstrated that, for the same chlorine dosage, a two-step addition of chlorine (two-step chlorination) was significantly more efficient in disinfecting a primary sewage effluent than a one-step addition of chlorine (one-step chlorination), and shown how the two-step chlorination was optimized with respect to time interval and dosage ratio. Two-step chlorination of the sewage effluent attained its highest disinfection efficiency at a time interval of 19 s and a dosage ratio of 5:1. Compared to one-step chlorination, two-step chlorination enhanced the disinfection efficiency by up to 0.81- or even 1.02-log for two different chlorine doses and contact times. An empirical relationship involving disinfection efficiency, time interval and dosage ratio was obtained by best fitting. Mechanisms (including a higher overall Ct value, an intensive synergistic effect, and a shorter recovery time) were proposed for the higher disinfection efficiency of two-step chlorination in the sewage effluent disinfection. Annual chlorine consumption costs in one-step and two-step chlorination of the primary sewage effluent were estimated. Compared to one-step chlorination, two-step chlorination reduced the cost by up to 16.7%. (C) 2016 Elsevier Ltd. All rights reserved.

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