Disinfection By-product Formation Kinetic of a Water Treatment Plant on Kinmen Island
Date Issued
2014
Date
2014
Author(s)
Ke, Hsien-Chun
Abstract
Human activity and regular drought weather increases the dissolved organic matter in fresh water reservoirs on Kinmen Island near the southeast shore of China. This results in substantial disinfection by-product formation in finished water which easily exceeded Taiwan EPA’s drinking water standard (80 μgL-1 for total trihalomethanes). The formation kinetic experiments were conducted using raw water from TaiLake, one of the major reservoirs on Kinmen Island. The formation kinetic curves indicated that high dosage of sodium hypochlorite lead to haloacetonitriles decay. For the same dosage, in low range, haloacetonitrile formation was higher with sodium hypochlorite than with chloramine. Trichloronitromethane formation was increased when chloramine was used as disinfectant. Dichloroacetonitrle, one of major species of haloacetonitriles observed, might come from both dissolved organic nitrogen and chloramine. By using nitrogen isotope with GC-MS, dichloroacetonitrile formation from chloramine is correlated linearly with disinfectant exposure (CT value) despite the dosage. Dichloroacetonitrile formation ratio from DON was increased at low disinfectant exposure (with chloramine initial dosage, 14N-DCAN to 15N-DCAN formation ratio was 48.8:50.2 in seven days raction in this study). Slow sand filtration in water treatment plant removes haloacetonitrles and haloacetic acids effectively. Different DBPs formation normalized by organic carbon unit kinetic and potential results from treatment process effluents was observed, which sμggest treatment process affect water quality (SUVA, DON, DIN, etc.). Simulated distribution system test indicated that peak trihalomethanes formation can be observed within 24 hours of retention time (trihlaomethane formation 111.2 μgL-1 in 24 hours SDS test for disinfection effluent sample on site). The results provide evidence that simultaneous prechlorination and postchloramination can be applied to better control regulated total trihalomethanes and potential nitrogenous disinfection by-product formation.
Subjects
氯胺
消毒副產物
三鹵甲烷
鹵乙腈
三氯硝基甲烷
SDGs
Type
thesis
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