Removal of disinfection byproducts and toxicity of chlorinated water by post-treatments of ultraviolet/hydrogen peroxide and ultraviolet/peroxymonosulfate

Post-treatment of ultraviolet (UV) irradiation is not efficient in eliminating toxicity of chlorinated water. Removal of disinfection byproducts (DBPs) and toxicity of chlorinated water by UV/hydrogen peroxide (UV/ H2O2 ) and UV/peroxymonosulfate (UV/PMS) was investigated. In the absence of bromide, adding H2O2 or PMS enhanced the removal of nitrogenous DBPs and total organic chlorine (TOCl) than UV alone (1200 mJ/cm(2)). UV/ PMS decreased the cytotoxicity from 10.6 to 4.4 mg-Phenol/L and genotoxicity from 7.1 to 2.0 mu g-4-NQO/L, more efficient than UV/H2O2. However, results were quite different in the presence of bromide. PMS led to the increased formation of total organic bromine (TOBr) in chlorinated water. UV/PMS was therefore less efficient in toxicity removal than UV/H2O2 . In the presence of bromide, UV/H2O2 decreased the cytotoxicity and genotoxicity by 85% and 68%, while UV/PMS only removed the cytotoxicity and genotoxicity by 59% and 46%. In the UV/PMS process, SO4'- was more efficient on toxicity removal than 'OH. Contributions of UV irradiation, 'OH and SO4'- were 55%, 14% and 31% to cytotoxicity removal, and 49%, 15% and 36% to genotoxicity removal. This study demonstrated the feasibility of using UV/H2O2 and UV/PMS as post-treatments to enhance the removal of DBPs and toxicity of chlorinated water.

Automated summary

This study investigated the removal of disinfection byproducts (DBPs) and toxicity of chlorinated water using post-treatments of UV/hydrogen peroxide (UV/H2O2) and UV/peroxymonosulfate (UV/PMS). The results showed that adding H2O2 or PMS improved the removal of nitrogenous DBPs and total organic chlorine (TOCl) compared to UV alone. However, the removal efficiency was reduced in the presence of bromide. UV/H2O2 was more effective in removing cytotoxicity and genotoxicity than UV/PMS. In the UV/PMS process, SO4'- was more efficient in removing toxicity than 'OH.