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

Abstract

a b s t r a c tThe 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.

Ecotoxicological screening of reclaimed disinfected wastewater by Vibrio fischeri bioassay after a chlorination–dechlorination process

“…But this oxidation does not usually lead only to a complete mineralization, but also to a fragmentation of larger size molecules into smaller sizes after chlorination [18]. Hence, an increase of chlorine levels in treated wastewater would promote halogenation reactions of intermediate products and the formation of DBPs.…”

Consequence of chitosan treating on the adsorption of humic acid by granular activated carbon

“…HA can affect water quality adversely by the undesirable colour (at concentrations above 5 mg/L), odour and taste [4,6], serve as food for bacterial growth, and trap heavy metals, pesticides and herbicides [7][8][9] which causes contamination of ground and surface water due to excess limits of their acceptable concentrations [10]. Different methods applied for remediation of humic substances include ozonation, biofiltration [11], membrane technology [12], coagulation [13], flotation [2], ion-exchange [14,15] and adsorption [16]. Adsorption is usually the simplest and most cost-effective technique [5].…”

Disinfection and DBPs removal in drinking water treatment: A perspective for a green technology

“…Side of the disinfection manner implicates reducing DBP precursors; mostly total organic carbon (TOC), by coagulation, water softening, or filtration (Ji et al, 2008;Ghernaout and Ghernaout, 2012b). An elevated TOC level (more than 2.0 mg/L) points out an elevated capacity for DBP generation.…”