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Xin Yang - One of the best experts on this subject based on the ideXlab platform.
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Tetracycline antibiotics as precursors of dichloroacetamide and other disinfection byproducts during chlorination and Chloramination.
Chemosphere, 2020Co-Authors: Kai-li Shao, Huang Huang, Xin YangAbstract:Pollution of natural water and even source water with pharmaceuticals is problematic worldwide and raises concern about the possibility of disinfection byproduct (DBP) formation during subsequent water treatment. In this study, the formation of DBPs, especially dichloroacetamide (DCAcAm), was investigated during chlorination and Chloramination of tetracyclines, which are a class of broad-spectrum antibiotics. DBPs including DCAcAm were formed during chlorination and Chloramination of tetracycline (TC). Although the concentrations and theoretical cytotoxicity of the DBPs formed from TC were affected by the contact time, disinfectant dose, and pH, DCAcAm was the main contributor determining the yields and cytotoxicity of the measured DBPs. The DCAcAm yields from four tetracycline antibiotics ranged from 0.43% to 54.26% for chlorination. For Chloramination, the DCAcAm yields reached 44.57%, and the nitrogen in DCAcAm mainly came from tetracycline antibiotics rather than chloramines. ClO2 pre-oxidation and UV photolysis decreased DCAcAm formation during chlorination and Chloramination of TC. The high yields observed in this study suggest that tetracycline antibiotics are possible precursors of DCAcAm.
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ClO2 pre-oxidation impacts the formation and nitrogen origins of dichloroacetonitrile and dichloroacetamide during subsequent Chloramination
Water research, 2020Co-Authors: Kai-li Shao, Huang Huang, Xin YangAbstract:Abstract Chlorine dioxide (ClO2) can be used as a pre-oxidant when Chloramination is performed in water treatment plants. However, the effects of ClO2 pre-oxidation on the formation of nitrogenous disinfection by-products, such as dichloroacetonitrile (DCAN) and dichloroacetamide (DCAcAm), during Chloramination are not well understood. In this study, the effects of ClO2 pre-oxidation on the formation of DCAN and DCAcAm during Chloramination of 28 model compounds and seven real water samples were investigated. The sources of nitrogen for DCAN and DCAcAm formation were investigated using 15N-labeled monochloramine. ClO2 pre-oxidation affected DCAN and DCAcAm formation during Chloramination of model compounds in different ways. ClO2 pre-oxidation increased unlabeled and 15N-labeled DCAN and DCAcAm formation during Chloramination of six amino acids and peptides and five indoles and tertiary amines. ClO2 pre-oxidation decreased DCAN formation but increased DCAcAm formation during Chloramination of three hydroxybenzamide compounds, but had the opposite effects for four tetracyclines. ClO2 pre-oxidation generally decreased DCAN and DCAcAm formation during Chloramination of the phenolic compounds that are precursors not containing nitrogen. 2-Aminoacetophenone, formamid-trans-muconic acid, and unsaturated ketones were found to be transformation products of ClO2 oxidation of 3-methylindole, salicylamide, and resorcinol, respectively. Possible DCAN and DCAcAm formation pathways during Chloramination after ClO2 oxidation were identified. For most of the water samples, ClO2 pre-oxidation decreased the amounts of DCAN and DCAcAm formed during Chloramination by 36%–70% and 11%–59%, respectively. This may have been caused by ClO2 oxidation destroying phenolic precursors and macromolecular proteins rather than amino acids in the water samples.
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effects of ozone and ozone peroxide pretreatments on disinfection byproduct formation during subsequent chlorination and Chloramination
Journal of Hazardous Materials, 2012Co-Authors: Xin Yang, Wanhong Guo, Jinfeng Peng, Yongmei Liang, Baiyang Chen, Wei Liu, Lu LiuAbstract:Ozone (O3) and ozone/hydrogen peroxide (O3/H2O2) can be used in water treatment facilities to remove many organic micropollutants with taste, odor, and color implications. The effects of O3 and O3/H2O2 on the formation of disinfection byproducts (DBPs) in subsequent chlorination and Chloramination processes, however, are not well determined. In this study, we compared the yields of a series of regulated and emerging DBPs during sequenced O3-Cl2, O3/H2O2-Cl2, O3-NH2Cl, and O3/H2O2-NH2Cl oxidation of 11 samples, each with different hydrophobicity, bromide concentration, soluble microbial products, and humic substances. For most water, pretreatment with O3 and O3/H2O2 increased the formation of chloral hydrate (CH), trichloronitromethane (TCNM) and haloketones (HKs) but lowered the yields of haloacetonitriles (HANs) during chlorination processes. Compared with O3 alone, O3/H2O2 in combination generated more CH and HKs during chlorination, and their extents of formation appeared to depend on the O3 doses. In terms of Chloramination, both O3 and O3/H2O2 reduced THM, HAA, and HAN formation significantly without increasing CH, TCNM, or HKs. These results suggest that O3 or O3/H2O2 pretreatments may provide some benefits for the Chloramination process in controlling regulated and emerging DBPs in waters without high bromide content.
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Effects of ozone and ozone/peroxide pretreatments on disinfection byproduct formation during subsequent chlorination and Chloramination.
Journal of hazardous materials, 2012Co-Authors: Xin Yang, Wanhong Guo, Jinfeng Peng, Yongmei Liang, Baiyang Chen, Wei Liu, Lu LiuAbstract:Ozone (O3) and ozone/hydrogen peroxide (O3/H2O2) can be used in water treatment facilities to remove many organic micropollutants with taste, odor, and color implications. The effects of O3 and O3/H2O2 on the formation of disinfection byproducts (DBPs) in subsequent chlorination and Chloramination processes, however, are not well determined. In this study, we compared the yields of a series of regulated and emerging DBPs during sequenced O3-Cl2, O3/H2O2-Cl2, O3-NH2Cl, and O3/H2O2-NH2Cl oxidation of 11 samples, each with different hydrophobicity, bromide concentration, soluble microbial products, and humic substances. For most water, pretreatment with O3 and O3/H2O2 increased the formation of chloral hydrate (CH), trichloronitromethane (TCNM) and haloketones (HKs) but lowered the yields of haloacetonitriles (HANs) during chlorination processes. Compared with O3 alone, O3/H2O2 in combination generated more CH and HKs during chlorination, and their extents of formation appeared to depend on the O3 doses. In terms of Chloramination, both O3 and O3/H2O2 reduced THM, HAA, and HAN formation significantly without increasing CH, TCNM, or HKs. These results suggest that O3 or O3/H2O2 pretreatments may provide some benefits for the Chloramination process in controlling regulated and emerging DBPs in waters without high bromide content.
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precursors and nitrogen origins of trichloronitromethane and dichloroacetonitrile during chlorination Chloramination
Chemosphere, 2012Co-Authors: Xin Yang, Qianqian Shen, Wanhong Guo, Jinfeng Peng, Yongmei LiangAbstract:Abstract The formation of trichloronitromethane (TCNM) and dichloroacetonitrile (DCAN) was investigated during chlorination and Chloramination of 31 organic nitrogen (org-N) compounds, including amino acids, amines, dipeptides, purines, pyrimidones and pyrroles. Tryptophan and alanine generated the greatest amount of TCNM during chlorination process and asparagine and tyrosine yielded the highest amount of TCNM during Chloramination process. Tryptophan, tyrosine, asparagine, and alanine produced more DCAN than other org-N compounds regardless of chlorination or Chloramination. TCNM and DCAN formation was higher by chlorination than by Chloramination. NH 2 Cl:org-N molar ratios, reaction time, and pH affected N-DBPs formation in varying degrees. TCNM and DCAN yields were usually high during Chloramination of tyrosine, asparagine, and methylpyrrole under the following reaction conditions: NH 2 Cl:org-N molar ratios greater than 10, reaction time for 1 d, and at pH 7.2. NH 2 Cl as a major nitrogen origin in TCNM and DCAN was confirmed via labeled 15 N-monochloramine during Chloramination of tyrosine, asparagine and methylpyrrole. In contrast, the majority of nitrogen in TCNM originated from glycine, and that in DCAN originated from pyrrole. Based on the intermediates identified by gas chromatography/mass spectrometry (GC/MS), a pathway scheme was proposed for TCNM and DCAN formation.
Naiyun Gao - One of the best experts on this subject based on the ideXlab platform.
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Formation of Nitrosodipropylamine from Nitrogenous Contaminants (Amines and Amine-Based Pesticides) in Water During Chloramination
Water Air & Soil Pollution, 2020Co-Authors: Chao Zhou, Naiyun Gao, Jinchao Bai, Hao Wang, Jianhai Sun, Yiqiong Yang, Xiaodong ZhangAbstract:Chloramination of drinking water and wastewater can generate carcinogenic nitrosamines, among which, nitrosodipropylamine (NDPA) with large molecular weight and weak polarity has been commonly found. However, knowledge on the formation of NDPA remains highly limited. Laboratory tests were conducted to quantify NDPA formation during Chloramination of nitrogenous precursors, including dipropylamine and methyldipropylamine, and pesticides such as trifluralin, oryzalin, and vernolat. Results showed that all precursors exhibited > 10.0% NDPA yields after 24 h. Oryzalin and trifluralin accomplished the highest (13.63%) and lowest (11.31%) yield, respectively. Maximal yields of all precursors were observed at pH 9.0 and temperature 288 K. Maximums of NDPA yield from oryzalin (18.27%) and vernolat (19.54%) were formed at Cl:N of 0.7:1.0, but maximal yields of dipropylamine (18.44%), methyldipropylamine (22.98%), and trifluralin (33.06%) were achieved at Cl:N of 1.2:1.0. Maximal NDPA yields of dipropylamine (37.14%), methyldipropylamine (32.84%), and vernolat (49.02%) were observed at [NH2Cl]0:[precursor]0 = 500, but highest yields of trifluralin (30.24%) and oryzalin (25.53%) were accomplished at [NH2Cl]0:[precursor]0 = 50. Bromide and organic contents in tap and raw water reduced NDPA due to competition for NH2Cl. Chloramination of water impacted by amines and pesticides should be careful of NDPA formation.
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Effect of UV irradiation on iodinated trihalomethane formation during post-Chloramination.
Water research, 2018Co-Authors: Ying Xia, Yi-li Lin, Wenhai Chu, Yulin Tang, Ze-chen Gao, Tong-cheng Cao, Naiyun GaoAbstract:Abstract Ultraviolet (UV) irradiation has been widely used in drinking water treatment processes, but its influence on the formation of disinfection by-products (DBPs), especially the emerging iodinated trihalomethanes (I-THMs) during post-Chloramination remains unclear. This study evaluated the impact of low pressure (LP) UV treatment on the formation of I-THMs during post-Chloramination through two pathways. The first pathway is through the transition of DOM structure and composition during UV-Chloramination, resulting significant increase of I-THM formation with increasing UV dosage in different dissolved organic matter (DOM)-containing water (49.7%–90.5% at 1160 mJ/cm2). With the application of excitation emission matrix-parallel factor analysis (EEM-PARAFAC), we found that I-THM formation in UV-chloraminated water correlated well with two ratios of three PARAFAC humic-like components (C3/C2 and C1/C2, R2 = 0.958–1.000), suggesting that the ratios of fluorescent components can be used as reliable indicators for I-THM formation. Moreover, the shift in these fluorescent components is crucial for I-THM formation during UV-Chloramination. Another pathway for UV irradiation to affect I-THM formation during post-Chloramination is through the transformation of iodine species. Large amounts of reactive iodine species (HOI/I2 and I3−) can be generated directly in the mixed iodine system by UV light, leading to the enhancement of iodine utilization factor (IUF) (up to 0.040) after post-Chloramination. These results suggest that UV application to DOM-containing water may induce changes in organic precursors and iodine species so as to enhance I-THM formation during post-Chloramination.
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Chlor(am)ination of iopamidol: Kinetics, pathways and disinfection by-products formation
Chemosphere, 2017Co-Authors: Fu-xiang Tian, Yi-li Lin, Tian-yang Zhang, Shengji Xia, Wenhai Chu, Naiyun GaoAbstract:Abstract The degradation kinetics, pathways and disinfection by-products (DBPs) formation of iopamidol by chlorine and chloramines were investigated in this paper. The chlorination kinetics can be well described by a second-order model. The apparent second-order rate constants of iopamidol chlorination significantly increased with solution pH. The rate constants of iopamidol with HOCl and OCl − were calculated as (1.66 ± 0.09) × 10 −3 M −1 s −1 and (0.45± 0.02) M −1 s −1 , respectively. However, the Chloramination of iopamidol fitted well with third-order kinetics and the maximum of the apparent rate constant occurred at pH 7. It was inferred that the free chlorine (i.e., HOCl and OCl − ) can react with iopamidol while the combined chlorine species (i.e., NH 2 Cl and NHCl 2 ) were not reactive with iopamidol. The main intermediates during chlorination or Chloramination of iopamidol were identified using ultra performance liquid chromatography - electrospray ionization-mass spectrometry (UPLC-ESI-MS), and the destruction pathways including stepwise deiodination, hydroxylation as well as chlorination were then proposed. The regular and iodinated DBPs formed during chlorination and Chloramination of iopamidol were measured. It was found that iodine conversion from iopamidol to toxic iodinated DBPs distinctly increased during Chloramination. The results also indicated that although chloramines were much less reactive than chlorine toward iopamidol, they led to the formation of much more toxic iodinated DBPs, especially CHI 3 .
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Evaluation and reduction of THMs, DCAN and TCNM formation potential from chlorination and Chloramination of verapamil
Journal of Environmental Chemical Engineering, 2017Co-Authors: Xingya Wei, Naiyun GaoAbstract:Abstract Verapamil (VRPM) is a kind of pharmaceuticals that widely used over the world and frequently detected in wastewater treatment plants effluents and downstream river waters. VRPM also can be a kind of precursor for carbonaceous (C-) and nitrogenous (N-) disinfection by-products (DBPs) during disinfection in water treatment. The formation of trihalomethanes, dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM) from chlorination and Chloramination of VRPM was firstly examined and compared in this study. The impacts of chlorine or monochloramine dose, contact time, pH, bromide, Chloramination mode, temperature, and pre-oxidation were evaluated as well. It was found that chloroform (CF) was the major DBPs during chlorination, while N-DBPs became dominant in Chloramination. The yields of CF, DCAN and TCNM were increased significantly with increasing monochloramine dose. Unlike CF and DCAN, the yield of TCNM increased firstly and then deceased with contact time. The effect of pH on DBPs formation was significant both for chlorination and Chloramination of VRPM. Bromide was proposed to play an important role in DBPs formation during disinfection. Compared to ultraviolet/persulfate, ultraviolet/hydrogen peroxide was a better pre-oxidation to not only efficiently oxidize VRPM, but also significantly reduce DBPs formation.
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Chlorination and Chloramination of tetracycline antibiotics: Disinfection by-products formation and influential factors
Ecotoxicology and environmental safety, 2014Co-Authors: Shiqing Zhou, Naiyun Gao, Yisheng Shao, Shumin Zhu, Jing DengAbstract:Abstract Formation of disinfection by-products (DBPs) from chlorination and Chloramination of tetracycline antibiotics (TCs) was comprehensively investigated. It was demonstrated that a connection existed between the transformation of TCs and the formation of chloroform (CHCl3), carbon tetrachloride (CCl4), dichloroacetonitrile (DCAN) and dichloroacetone (DCAce). Factors evaluated included chlorine (Cl2) and chloramine(NH2Cl) dosage, reaction time, solution pH and disinfection modes. Increased Cl2/NH2Cl dosage and reaction time improved the formation of CHCl3 and DCAce. Formation of DCAN followed an increasing and then decreasing pattern with increasing Cl2 dosage and prolonged reaction time. pH affected DBPs formation differently, with CHCl3 and DCAN decreasing in chlorination, and having maximum concentrations at pH 7 in Chloramination. The total concentrations of DBPs obeyed the following order: chlorination>Chloramination>pre-chlorination (0.5 h)>pre-chlorination (1 h)>pre-chlorination (2 h).
Hongjun Lin - One of the best experts on this subject based on the ideXlab platform.
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use of multiple regression models to evaluate the formation of halonitromethane via chlorination Chloramination of water from tai lake and the qiantang river china
Chemosphere, 2015Co-Authors: Huachang Hong, Yujing Xiong, Lingya Qian, Zhuoqun Xiao, Hongjun LinAbstract:Abstract The deterioration of water quality, especially organic pollution in Tai Lake and the Qiantang River, have recently received attention in China. The objectives of this study were to evaluate the formation of halonitromethanes (HNMs) using multiple regression models for chlorination and Chloramination and to identify the key factors that influence the formation of HNMs in Tai Lake and the Qiantang River. The results showed that the total formation of HNMs (T-HNMs) during chlorination and Chloramination could be described using the following models: (1) T- HNM Cl 2 = (10)5.267(DON)6.645(Br−)0.737(DOC)−5.537(Cl2)0.333(t)0.165 (R2 = 0.974, p
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Use of multiple regression models to evaluate the formation of halonitromethane via chlorination/Chloramination of water from Tai Lake and the Qiantang River, China
Chemosphere, 2014Co-Authors: Huachang Hong, Yujing Xiong, Lingya Qian, Zhuoqun Xiao, Hongjun LinAbstract:Abstract The deterioration of water quality, especially organic pollution in Tai Lake and the Qiantang River, have recently received attention in China. The objectives of this study were to evaluate the formation of halonitromethanes (HNMs) using multiple regression models for chlorination and Chloramination and to identify the key factors that influence the formation of HNMs in Tai Lake and the Qiantang River. The results showed that the total formation of HNMs (T-HNMs) during chlorination and Chloramination could be described using the following models: (1) T- HNM Cl 2 = (10)5.267(DON)6.645(Br−)0.737(DOC)−5.537(Cl2)0.333(t)0.165 (R2 = 0.974, p
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Effects of ozone pretreatment on the formation of disinfection by-products and its associated bromine substitution factors upon chlorination/Chloramination of Tai Lake water.
The Science of the total environment, 2014Co-Authors: Fangyuan Wang, Huachang Hong, Mengyong Ruan, Hongjun Lin, Yu Zhang, Xiaoling ZhouAbstract:Abstract This study investigated the effects of preozonation on disinfection by-products (DBPs) formation during chlorination and Chloramination of the water collected from Tai Lake. Results showed that the high ozone dose (0.6–1.0 mg O3/mg DOC) pretreatment reduced the yields of trihaloacetic acids (reduced 62–63% in chlorination), dihaloacetonitriles (reduced 53–55% and 14–26% in chlorination and Chloramination, respectively) and trihaomethanes (reduced 19% in Chloramination), but markedly increased the formation of halonitromethanes (increased 4.7–5.6 times in chlorination and 2.1–2.7 times in Chloramination), haloketones (increased 4.8–7.1 times in chlorination and 2.5–2.9 times in Chloramination) and dihaloacetic acids (increased 1.5–2.4 times in chlorination and 0.3–0.6 times in Chloramination). Thus the high ozone dose pretreatment should be avoided during chlorination/Chloramination of Tai Lake water. Also, Chloramination (with and without preozonation) produced much lower DBPs yields as compared with chlorination (with and without preozonation), indicating that chloramine was a better choice to control the DBPs yields. Further analysis also revealed that the bromine substitution factors (BSFs) of DBPs varied with disinfection mode. In chlorinamination, the BSFs generally showed a decrease trend with the ozone dose, yet in chlorination, the BSFs mostly exhibited first an increase and then a decrease trend. Moreover, the BSFs of DBPs in Chloramination (with or without preozonation) were dominantly lower than those in chlorination (with or without preozonation).
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factors affecting thms haas and hnms formation of jin lan reservoir water exposed to chlorine and monochloramine
Science of The Total Environment, 2013Co-Authors: Huachang Hong, Yujing Xiong, Mengyong Ruan, Fanglei Liao, Hongjun Lin, Yan LiangAbstract:The formations of THMs, HAAs, and HNMs from chlorination and Chloramination of water from Jinlan Reservoir were investigated in this study. Results showed that monochloramine rather than chlorine generally resulted in lower concentration of DBPs, and the DBPs formation varied greatly as the treatment conditions changed. Specifically, the yields of THMs, HAAs and HNMs all increased with the high bromide level and high disinfectant dose both during chlorination and Chloramination. The longer reaction time had a positive effect on the formation of THMs, HAAs and HNMs during chlorination and HNMs during Chloramination. However, no time effect was observed on the formation of THMs and HAAs during Chloramination. An increase in pH enhanced the levels of THMs and HNMs upon chlorination but reduced levels of HNMs upon Chloramination. As for the THMs in Chloramination and HAAs in chlorination and Chloramination, no obvious pH effect was observed. The elevated temperature significantly increased the yields of THMs during chlorination and HNMs during Chloramination, but has no effect on THMs and HAAs yields during Chloramination. In the same temperature range, the formation of HAAs and HNMs in chlorination showed a first increasing and then a decreasing trend. In Chloramination study, addition of nitrite markedly increased the formation of HNMs but had little impact on the formation of THMs and HAAs. While in chlorination study, the presence of high nitrite levels significantly reduced the yields of THMs, HAAs and HNMs. Range analysis revealed that the bromide and disinfectant levels were the major factors affecting THMs, HAAs and HNMs formation, in both chlorination and Chloramination. Finally, comparisons of the speciation of mono-halogenated, di-halogenated, tri-halogenated HAAs and HNMs between chlorination and monoChloramination were also conducted, and factors influencing the speciation pattern were identified.
Huachang Hong - One of the best experts on this subject based on the ideXlab platform.
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use of multiple regression models to evaluate the formation of halonitromethane via chlorination Chloramination of water from tai lake and the qiantang river china
Chemosphere, 2015Co-Authors: Huachang Hong, Yujing Xiong, Lingya Qian, Zhuoqun Xiao, Hongjun LinAbstract:Abstract The deterioration of water quality, especially organic pollution in Tai Lake and the Qiantang River, have recently received attention in China. The objectives of this study were to evaluate the formation of halonitromethanes (HNMs) using multiple regression models for chlorination and Chloramination and to identify the key factors that influence the formation of HNMs in Tai Lake and the Qiantang River. The results showed that the total formation of HNMs (T-HNMs) during chlorination and Chloramination could be described using the following models: (1) T- HNM Cl 2 = (10)5.267(DON)6.645(Br−)0.737(DOC)−5.537(Cl2)0.333(t)0.165 (R2 = 0.974, p
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Use of multiple regression models to evaluate the formation of halonitromethane via chlorination/Chloramination of water from Tai Lake and the Qiantang River, China
Chemosphere, 2014Co-Authors: Huachang Hong, Yujing Xiong, Lingya Qian, Zhuoqun Xiao, Hongjun LinAbstract:Abstract The deterioration of water quality, especially organic pollution in Tai Lake and the Qiantang River, have recently received attention in China. The objectives of this study were to evaluate the formation of halonitromethanes (HNMs) using multiple regression models for chlorination and Chloramination and to identify the key factors that influence the formation of HNMs in Tai Lake and the Qiantang River. The results showed that the total formation of HNMs (T-HNMs) during chlorination and Chloramination could be described using the following models: (1) T- HNM Cl 2 = (10)5.267(DON)6.645(Br−)0.737(DOC)−5.537(Cl2)0.333(t)0.165 (R2 = 0.974, p
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Effects of ozone pretreatment on the formation of disinfection by-products and its associated bromine substitution factors upon chlorination/Chloramination of Tai Lake water.
The Science of the total environment, 2014Co-Authors: Fangyuan Wang, Huachang Hong, Mengyong Ruan, Hongjun Lin, Yu Zhang, Xiaoling ZhouAbstract:Abstract This study investigated the effects of preozonation on disinfection by-products (DBPs) formation during chlorination and Chloramination of the water collected from Tai Lake. Results showed that the high ozone dose (0.6–1.0 mg O3/mg DOC) pretreatment reduced the yields of trihaloacetic acids (reduced 62–63% in chlorination), dihaloacetonitriles (reduced 53–55% and 14–26% in chlorination and Chloramination, respectively) and trihaomethanes (reduced 19% in Chloramination), but markedly increased the formation of halonitromethanes (increased 4.7–5.6 times in chlorination and 2.1–2.7 times in Chloramination), haloketones (increased 4.8–7.1 times in chlorination and 2.5–2.9 times in Chloramination) and dihaloacetic acids (increased 1.5–2.4 times in chlorination and 0.3–0.6 times in Chloramination). Thus the high ozone dose pretreatment should be avoided during chlorination/Chloramination of Tai Lake water. Also, Chloramination (with and without preozonation) produced much lower DBPs yields as compared with chlorination (with and without preozonation), indicating that chloramine was a better choice to control the DBPs yields. Further analysis also revealed that the bromine substitution factors (BSFs) of DBPs varied with disinfection mode. In chlorinamination, the BSFs generally showed a decrease trend with the ozone dose, yet in chlorination, the BSFs mostly exhibited first an increase and then a decrease trend. Moreover, the BSFs of DBPs in Chloramination (with or without preozonation) were dominantly lower than those in chlorination (with or without preozonation).
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factors affecting thms haas and hnms formation of jin lan reservoir water exposed to chlorine and monochloramine
Science of The Total Environment, 2013Co-Authors: Huachang Hong, Yujing Xiong, Mengyong Ruan, Fanglei Liao, Hongjun Lin, Yan LiangAbstract:The formations of THMs, HAAs, and HNMs from chlorination and Chloramination of water from Jinlan Reservoir were investigated in this study. Results showed that monochloramine rather than chlorine generally resulted in lower concentration of DBPs, and the DBPs formation varied greatly as the treatment conditions changed. Specifically, the yields of THMs, HAAs and HNMs all increased with the high bromide level and high disinfectant dose both during chlorination and Chloramination. The longer reaction time had a positive effect on the formation of THMs, HAAs and HNMs during chlorination and HNMs during Chloramination. However, no time effect was observed on the formation of THMs and HAAs during Chloramination. An increase in pH enhanced the levels of THMs and HNMs upon chlorination but reduced levels of HNMs upon Chloramination. As for the THMs in Chloramination and HAAs in chlorination and Chloramination, no obvious pH effect was observed. The elevated temperature significantly increased the yields of THMs during chlorination and HNMs during Chloramination, but has no effect on THMs and HAAs yields during Chloramination. In the same temperature range, the formation of HAAs and HNMs in chlorination showed a first increasing and then a decreasing trend. In Chloramination study, addition of nitrite markedly increased the formation of HNMs but had little impact on the formation of THMs and HAAs. While in chlorination study, the presence of high nitrite levels significantly reduced the yields of THMs, HAAs and HNMs. Range analysis revealed that the bromide and disinfectant levels were the major factors affecting THMs, HAAs and HNMs formation, in both chlorination and Chloramination. Finally, comparisons of the speciation of mono-halogenated, di-halogenated, tri-halogenated HAAs and HNMs between chlorination and monoChloramination were also conducted, and factors influencing the speciation pattern were identified.
Ching-hua Huang - One of the best experts on this subject based on the ideXlab platform.
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N-nitrosodimethylamine (NDMA) formation potential of amine-based water treatment polymers: Effects of in situ Chloramination, breakpoint chlorination, and pre-oxidation.
Journal of hazardous materials, 2014Co-Authors: Sang Hyuck Park, Lokesh P. Padhye, Pei Wang, Min Cho, Jae-hong Kim, Ching-hua HuangAbstract:Recent studies show that cationic amine-based water treatment polymers may be important precursors that contribute to formation of the probable human carcinogen N-nitrosodimethylamine (NDMA) during water treatment and disinfection. To better understand how water treatment parameters affect NDMA formation from the polymers, the effects of in situ Chloramination, breakpoint chlorination, and pre-oxidation on the NDMA formation from the polymers were investigated. NDMA formation potential (NDMA-FP) as well as dimethylamine (DMA) residual concentration were measured from poly(epichlorohydrin dimethylamine) (polyamine) and poly(diallyldimethylammonium chloride) (polyDADMAC) solutions upon reactions with oxidants including free chlorine, chlorine dioxide, ozone, and monochloramine under different treatment conditions. The results supported that dichloramine (NHCl2) formation was the critical factor affecting NDMA formation from the polymers during in situ Chloramination. The highest NDMA formation from the polymers occurred near the breakpoint of chlorination. Polymer chain breakdown and transformation of the released DMA and other intermediates were important factors affecting NDMA formation from the polymers in pre-oxidation followed by post-Chloramination. Pre-oxidation generally reduced NDMA-FP of the polymers; however, the treatments involving pre-ozonation increased polyDADMAC's NDMA-FP and DMA release. The strategies for reducing NDMA formation from the polymers may include the avoidance of the conditions favorable to NHCl2 formation and the avoidance of polymer exposure to strong oxidants such as ozone.