AI Article Synopsis
- Ultraviolet (UV) irradiation combined with chlor(am)ination is commonly used in many Chinese cities' secondary water supply systems, but the formation of disinfection by-products (DBPs) in this mixed system is not fully understood.
- A study explored how various factors, like the ratios of chlorine to chloramine, UV exposure, pH levels, and types of organic matter, impacted DBP formation.
- Results showed that higher ratios of free chlorine reduced DBP levels, and that water with humic acid produced the most DBPs, while acidic conditions helped mitigate DBP toxicity; the presence of bromine (Br) also led to decreased DBP formation under UV treatment.
Article Abstract
In recent years, ultraviolet (UV) irradiation coupled with chlor(am)ination process is ubiquitous in secondary water supply systems in many cities of China. However, the disinfection by-products (DBPs) formation in a UV-activated mixed chlorine/chloramine system (MCCS) still remains unclear. In this study, the DBPs formation in a UV-activated MCCS was systematically investigated, considering influencing factors including the mass ratios of free chlorine to NHCl, UV irradiation, pH values, NOM types, Br concentration and toxicity of the DBPs. Results indicated that DBPs formation decreased remarkably as mass ratio of free chlorine to NHCl changed from 5:0 to 0:5. The DBPs formation in humic acid (HA)-containing water was the highest, followed by those in fulvic acid (FA) and algal organic matter (AOM). Besides, better control of the DBP-related calculated toxicity can be achieved in acidic conditions regardless of the UV irradiation. Furthermore, in the presence of Br, a significant reduction of DBPs formation could be achieved in a UV-activated MCCS. The findings also demonstrated that DBPs formation in real water can be effectively reduced at high UV fluence in a MCCS.
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| http://dx.doi.org/10.1016/j.jhazmat.2020.124373 | DOI Listing |
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