Details

Autor(en) / Beteiligte

• Li, Yu
• Yang, Mengting
• Zhang, Xiangru
• Jiang, Jingyi
• Liu, Jiaqi
• Yau, Cie Fu
• Graham, Nigel J.D.
• Li, Xiaoyan

Titel

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

Ist Teil von

• Water research (Oxford), 2017-01, Vol.108, p.339-347

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2017

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• 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%. [Display omitted] •Two-step chlorination was more efficient in disinfection than one-step chlorination.•Two-step chlorination was optimized in terms of time interval and dosage ratio.•Three mechanisms might be responsible for the higher disinfection efficiency.