Impact of chitosan and polyacrylamide on formation of carbonaceous and nitrogenous disinfection by-products.
Coagulation is one of the most commonly used practices in water treatment to remove natural organic matter, which can serve as precursors for disinfection by-products (DBPs). Furthermore, some coagulant aids, particularly amine-based polymers, could foster the formation of both carbonaceous and nitrogenous DBPs (C-DBPs and N-DBPs, respectively). In this study, we evaluated the formation potentials of 11 C-DBPs and N-DBPs during chloramination when two coagulant aids, chitosan and polyacrylamide (PAM), were used under typical water treatment conditions. Our results suggest that both chitosan and PAM promote the formation of N-DBPs, while neither affects the formation of C-DBPs. We further investigated a potential method to mitigate the formation of N-DBPs. Methyl iodide (MeI), an alkylating agent, was effective at reducing the formation of N-DBPs by converting amine to quaternary ammonium groups in chitosan.1H-NMR results confirmed that the quaternarization reaction did take place. This study reports that chitosan, a natural coagulant, and PAM contribute to the formation of toxic DBPs. More importantly, it provides a preventative strategy for curbing the formation of DBPs through chemical structural modification.
Department of Civil and Environmental Engineering, Villanova University Villanova, PA 19085, USA.
Zhao
Z
Li
Department of Civil and Environmental Engineering, Villanova University Villanova, PA 19085, USA; College of Municipal and Environmental Engineering, Harbin Institute of Technology Harbin, 150001, China.
Ting
T
Chen
College of Municipal and Environmental Engineering, Harbin Institute of Technology Harbin, 150001, China.
Fuyi
F
Cui
Civil and Environmental Programs, Pennsylvania State University Middletown, PA 17057, USA.
Yuefeng
Y
Xie
Department of Civil and Environmental Engineering, Villanova University Villanova, PA 19085, USA. Electronic address: wenqing.xu@villanova.edu.
Wenqing
W
Xu
D000180:Acrylic Resins / Q000494:pharmacology*; D002244:Carbon / Q000009:adverse effects; D048271:Chitosan / Q000494:pharmacology*; D004203:Disinfection; D054879:Halogenation; D009584:Nitrogen / Q000009:adverse effects; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D000099166:Polyacrylamides
D000180:Acrylic Resins; D002244:Carbon; D048271:Chitosan; D009584:Nitrogen; D014874:Water Pollutants, Chemical; D000099166:Polyacrylamides
Chitosan; Coagulation; Disinfection by-products; NDMA; Polyacrylamide; Quaternary ammonium groups