Removal of disinfection by-products precursors by polyaluminum chloride coagulation coupled with chlorination

摘要

The effect of coagulation coupled with chlorination (i.e., pre-, inter-, and post-chlorination) on the formation of disinfection by-products (DBPs) and the removal efficiency of DBPs precursors were investigated. Compared with coagulation coupling with pre-chlorination, coagulation coupled with inter-chlorination could lead a higher removal efficiency of dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA) and chloroacetic acids formation potential (CAAsFP). The CAAsFP/DOC value of residual DOC showed that coagulation with inter-chlorination has a beneficial effect on CAAs precursors removal. More DBPs were produced during inter-chlorination than that of pre-chlorination at pH 7.5, while less DBPs were produced during inter-chlorination than that of pre-chlorination at pH 5.5. In addition, the precipitate of humic acid (HA) after coagulation was chlorinated to study the kinetics of chlorine decay. The results showed that coagulated-HA had a higher reactivity with chlorine than aqueous-HA at pH 7.5. Furthermore, the trends of zeta potential during coagulation process suggested that the distribution of chlorine species had significant influence on the removing of DBPs precursors by coagulation coupled with chlorination. (c) 2008 Elsevier B.V. All rights reserved.