CHEMOSPHERE
·
2018
·
IF 4.427
Cong Li,Qiufeng Lin,Feilong Dong,Yuanhao Li,Feng Luo,Kejia Zhang
Chlorination is essential to provide safe drinking water . However, this process leads to the formation of disinfection byproducts (DBPs). In this study, tryptophan (Trp) has been selected as a precursor to conduct the chlorine disinfection. Moreover, the factors that affect the formation of trihalomethanes (THMs) and iodinated trihalomethanes (I-THMs) are investigated. The formation pathway of Trp chlorination is proposed based on the intermediate products identified. According to the experimental results, the formation of THMs and I-THMs during Trp chlorination fitted a new first-order kinetic model. The dosage of chlorine, temperature, pH and the ratio of bromide and iodide had major influence on the formation of THMs and I-THMs during chlorination. In addition, the inhibition of luminescent bacteria Vibrio fischeri in the water sample increased during Trp chlorination.
研究领域:
环境科学
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水处理工程
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DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Chao Fang,Jianglin Hu,Wenhai Chu,Shunke Ding,Tiantao Zhao,Xiaoyan Lu,Hongying Zhao,Daqiang Yin,Naiyun Gao
It is commonly acknowledged that proteins, comprising a large portion of dissolved organic nitrogen pool, are important precursors of disinfection by-products (DBPs). Moreover, proteins can also undergo degradation (e.g. enzymolysis) in aquatic environment or during biological treatment processes. In this study, a well-characterized protein, bovine serum albumin (BSA) was used as model compound to investigate the effect of enzymolysis on the formation of four classes of CX 3 R-type DBPs (i.e. trihalomethanes, haloacetaldehydes, haloacetonitriles, and haloacetamides) during chlorination. After enzymolysis, the three-dimension structure of BSA was destroyed, increasing the accessibility of inside amino acids to chlorine, thus enzyme-hydrolysed BSA exhibited higher chlorine demand and higher formation of total organic halogen (TOX) than un-hydrolysed BSA. Generally, enzyme-hydrolysed BSA produced more CX 3 R-type DBPs, which is due to the facilitation of fragmentation of BSA by enzymolysis. In the presence of bromide, enzymolysis promoted the formation of TOX to a greater extent than in the absence of bromide. The effect of enzymolysis on pre-oxidation efficiency in the control of CX 3 R-type DBPs was also investigated. It was found that the reduction in CX 3 R-type DBP formation from chlorinated enzyme-hydrolysed BSA was more significant than that from chlorinated un-hydrolysed BSA, but the former still exhibited higher calculated cytotoxicity than the latter, indicating the removal of CX 3 R-type DBP precursors was indirectly offset by the effect of enzymolysis. This study provides insights into the effect of the structural transformation of protein during water treatment processes on CX 3 R-type DBP formation.
研究领域:
环境科学
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水处理工程
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DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Jing Liu,Jing Wang,Jie Zhang,Yang Mu
In this study, the impact of Cu 2+ on the formation of iodo-trihalomethanes (I-THMs) during chlorination and chloramination of iodide-containing waters was investigated. Initially, the oxidant consumption and evolution of hypoiodous acid (HOI) were determined during disinfection in the presence of Cu 2+ and the interaction between natural organic matter humic acid (HA) and Cu 2+ was also analyzed. Subsequently, the formation of the I-THMs at various Cu 2+ concentrations was evaluated for chlorination and chloramination. Moreover, in order to explore the possible underlying mechanisms, five model compounds based on the HA structure were used to investigate the I-THMs formation with and without Cu 2+ during disinfection. The results indicated that the presence of Cu 2+ markedly affected the conformation of the HA rather than the HOI evolution during disinfection. The concentration of the I-THMs decreased from 34.5 ± 0.8 to 20.9 ± 0.8 nM as the Cu 2+ concentration increased from 0 to 20 μM during chlorination. In contrast, during chloramination, the total I-THMs concentration decreased from 320.7 ± 7.4 to 267.2 ± 10.7 nM as the Cu 2+ concentration increased from 0 to 5 μM and then increased to 315.0 ± 1.7 nM when the Cu 2+ concentration reached 20 μM. The disinfection experiments with the model compounds suggested that the impact of Cu 2+ on the I-THMs formation largely depended on the organic structures in the HA, thus leading to different results during chlorination and chloramination.
研究领域:
环境科学
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水处理工程
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DOI
PubMed
高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Chao Fang,Tian Ou,Xingyu Wang,Min Rui,Wenhai Chu
Ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) are widely used in drinking water treatment and wastewater recycling. However, limited information was available regarding their performance in removing trihalomethanes (THMs). The present study investigated the effect of feed solution characteristics and membrane fouling on THM removal by UF/NF/RO membranes. The results indicated that THMs were poorly removed by UF membrane, and the removal was dominated by hydrophobic adsorption. In contrast, high removal of THMs was observed for NF/RO membranes, which was contributed by both size exclusion and hydrophobic adsorption. By comparing the adsorption of THMs on NF/RO membranes at different feed concentration, it was found that the role of hydrophobic adsorption was more important at lower feed concentration. The removal of THMs by UF/NF/RO membranes increased with increasing feed concentration, which can be ascribed to the enhanced diffusion at higher concentration gradient. With increasing ionic strength, THM removal was decreased significantly for UF membrane, but the removal by NF/RO membranes remained largely unchanged. By comparing THM removal by clean and fouled membranes, the effect of membrane fouling was examined. The removal of most THMs (except trichloromethane) decreased after fouling for UF membrane, whereas decreased removal was only observed for iodinated THMs for fouled NF/RO membranes.
研究领域:
环境科学
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水处理工程
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产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2018
·
IF 4.61
Xiaoyang Shi,Ran Bi,Baoling Yuan,Xiaobin Liao,Zhenming Zhou,Fei Li,Wenjie Sun
Microcystis aeruginosa ( M. aeruginosa ) commonly blooms in summer while Cyclotella meneghiniana ( C. meneghiniana ) outbreaks in fall in water reservoirs of Southeast China. Pre-oxidation has been demonstrated to enhance the algae removal from chemical coagulation processes. However, excessive dosage of pre-oxidant can increase the disinfection by-products formation potential (DBPsFP). Additionally, the DBPs formation mechanisms from algae during the pre-oxidation-coagulation-chlorination processes have not well elucidated. In this study, the objectives were to investigate the trichloromethane (TCM) formation, the changes of water quality indexes, and the morphology changes of algal cells from M. aeruginosa or C. meneghiniana contaminated water during potassium permanganate (KMnO 4 ) or chlorine (Cl 2 ) pre-oxidation-coagulation-chlorination disinfection. The results showed that the TCM yield for two algal species decreased with the dosage increase of KMnO 4 pre-oxidation, but increased with the dosage increase of pre-chlorination. Therefore, the 2.0 mg/L KMnO 4 or 0.5 mg/L Cl 2 was proposed as the optimal dosage for preventing both M. aeruginosa blooms in summer and for C. meneghiniana outbreaks in fall. M. aeruginosa exhibited a slightly higher TCM yield than C. meneghiniana in these treatment processes. Based on the release of potassium (K) ion and SEM analysis, KMnO 4 had less damage on cell integrity than Cl 2 at the dosage ≤2.0 mg/L. In addition, C. meneghiniana was easier to be disrupted by both pre-oxidants than M. aeruginosa , combining with subsequent coagulation led to different value of dissolved organic carbon (DOC), UV–visible absorbance (UV 254 ) and turbidity .
研究领域:
环境科学
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水处理工程
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产品关联
DOI
PubMed
高影响因子
Journal of Environmental Sciences
·
2022
·
IF 6.796
Shuang Zhang,Yi-Li Lin,Tian-Yang Zhang,Chen-Yan Hu,Zhi Liu,Zheng-Yu Dong,Meng-Yuan Xu,Bin Xu
In this study, the formation of iodinated trihalomethanes (I-THMs) was systematically evaluated and compared for three treatment processes - (i) chlorination, (ii) monochloramine, and (iii) dichloramination - under different pH conditions. The results demonstrated that I-THM formation decreased in the order of monochloramination > dichloramination > chlorination in acidic and neutral pH. However, the generation of I-THMs increased in the dichloramination < chlorination < monochloramination order in alkaline condition. Specifically, the formation of I-THMs increased as pH increased from 5 to 9 during chlorination and monochloramination processes, while the maximum I-THM formation occurred at pH 7 during dichloramination. The discrepancy could be mainly related to the stability of the three chlor (am) ine disinfectants at different pH conditions. Moreover, in order to gain a thorough insight into the mechanisms of I-THM formation during dichloramination, further investigation was conducted on the influencing factors of DOC concentration and Br − /I − molar ratio. I-THM formation exhibited an increasing and then decreasing trend as the concentration of DOC increased from 1 to 7 mg-C/L, while the yield of I-THMs increased with increasing Br − /I − molar ratio from 5:0 to 5:10. During the three processes mentioned above, similar I-THM formation results were also obtained in real water, which indicates that the excessive generation of I-THMs should be paid special attention during the disinfection of iodide-containing water.
研究领域:
环境科学
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水处理工程
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DOI
PubMed
高影响因子
WATER RESEARCH
·
2020
·
IF 9.13
Di Zhang,Feifei Wang,Youli Duan,Shenghua Chen,Aihong Zhang,Wenhai Chu
Disinfection by-products (DBPs) are associated with various adverse health effects. Diversiform advanced treatment processes have been applied for the control of DBPs, but DBPs can still be frequently detected in tap water . Tea-leaves can be made into popular beverage and is itself a porous bio-adsorbent. By simulating tea brewing process, this study evaluated the removal of DBPs from drinking water during the tea brewing process. Removal of four trihalomethanes (THMs) and four haloacetamides (HAMs) by different fermentation degree tea-leaves was investigated. Little DBPs were removed by unfermented and semi-fermented tea-leaves (i.e., Meitan turquoise bud and Dahongpao tea) with less than 5% removal of HAMs, whereas 40% HAMs can be removed by fermented tea (i.e., Jinjunmei tea and Shuixian tea). Tea soup is neutral and slightly acidic, so little DBP hydrolysis was observed under typical tea-leaf brewing process. DBPs were mainly removed by volatilization and adsorption during tea brewing. Removal difference caused by DBP volatilization is very small. The DBP removal difference of four kinds of tea-leaves may be caused by fermentation degree. The surface of unfermented Meitan turquoise bud had a smooth and regular morphology, whereas a rough, irregular, hollow and spongy surface of fermented tea (i.e., Jinjunmei and Shuixian tea) was observed. Generally, the higher the degree of tea fermentation, the more adsorption sites, and the more removal of DBPs. Finally, the model, which takes the DBP initial concentration, tea-leaf dose and brewing time into account, was established under the experimental conditions to predict the variation of DBP concentration during tea brewing, and suggestions for DBP removal were provided to reduce DBP exposure risk. The integrated toxic risk during tea brewing was also investigated, and about 30% integrated cytotoxicity and 26% genotoxicity was reduced during Jinjunmei and Shuixian tea-leaf brewing.
研究领域:
环境科学
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公共卫生
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产品关联
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Chao Fang,Xingyu Wang,Rong Xiao,Shunke Ding,Baiyang Chen,Wenhai Chu
Reverse osmosis (RO), a promising technology for removing inorganic salts and a wide range of trace organic pollutants, is widely used in water treatment industry. In this study, the rejection of chlorinated, brominated, and iodinated trihalomethanes (THMs) by a multi-stage RO system was investigated. The results showed that the multi-stage RO system is effective in rejecting THMs, and THMs with large size, high hydrophobicity and low polarity were highly rejected. In the first stage, high percentage of THMs was adsorbed on RO membrane, and the THM rejection was dominated by both hydrophobic adsorption and size exclusion. The contribution of hydrophobic adsorption to THM rejection decreased significantly along RO stages due to decreased feed concentration, but the enhancement of size exclusion still ensured high rejection efficiencies for most THMs, indicating a compensation effect between two rejection mechanisms. Finally, to further understand the rejection in the multi-RO system from a perspective of THM property, multiple linear regression models were built. The impact of n -octanol-water partition coefficient (Log K ow ) was slightly higher than that of stokes radius in the first stage, which was consistent with the rejection mechanism. But dipole moment played an increasingly important role in the second and third stage, weakening the impact of Log K ow on THM rejection.
研究领域:
环境科学
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水处理工程
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Changjun Li,Naiyun Gao,Wenhai Chu,Tom Bond,Xingya Wei
Trihalomethane (THMs) and haloacetonitriles (HANs) are typical and frequently detected carbonaceous (C–) and nitrogenous (N–) disinfection by-products (DBPs) in water treatment , and amine acids (AAs) are important precursors of DBPs. However, previous researches mainly focused on free AAs and few investigations evaluated the DBPs formation potential of combined AAs, especially combined histidine . The formation of THMs and HANs from free and combined histidine and glycine during chlorination was firstly examined and compared in this study with an emphasis on their differences. The impacts of chlorine dose, pH, ammonia nitrogen and bromide were evaluated and mechanistic formation pathways were proposed. In comparison with free AAs, combined AAs generated more chloroform (CF, 125%–671%) but less dichloroacetonitrile (DCAN, 4.66%–87.5%) at all chlorine doses. The effect of solution pH on combined AAs was slighter than that on free AAs. During chloramination, both free AAs and combined AAs generated much smaller amounts of DBPs, especially DCAN (<9.01%), compared with chlorination. At any bromide dose, there was more bromine merging into THMs than DHANs, especially for combined AAs. At the beginning of chlorination, the combined AAs decomposed in three different ways: hydrolysis, decarboxylation and scission , leading to differing amounts of CF and DCAN compared with the free AAs.
研究领域:
环境科学
·
水处理工程
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化学
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DOI
高影响因子
Water
·
2024
·Vol. 16
·期 22
·3304
·
IF 3
Saber A. S. Ahmed,Hongyan Zhai,Soon-Thiam Khu
There is a rising concern about the safety risk that trihalomethanes (THMs) in drinking water pose. In this work, to adsorb THMs such as chloroform (TCM), dibromochloromethane (DBCM), bromodichloromethane (BDCM), and bromoform (TBM), we coated chitosan (CS) on coconut shell activated carbon (CAC). The adsorbents were characterized using BET, XRD, FTIR, and SEM techniques. The impact of various variables was examined, including contact time, quantity of adsorbent, initial pH, and initial THM concentrations. Under the same conditions, TCM was adsorbed most efficiently, followed by BDCM, DBCM, and TBM. When the pH was between 4 and 8, the adsorption of THMs onto the coconut shell activated carbon supported chitosan (CS/CAC) varied relatively little; however, when the pH increased above 8, the adsorption of THMs decreased. For THMs, CS/CAC adsorption was a chemical reaction and monolayer adsorption that fit better with the pseudo-second-order kinetic model and the Langmuir isotherm model. According to the thermodynamic study, THMs were adsorbed endothermically and spontaneously on CS/CAC. For column experiments, the adsorption of THMs was influenced by bed height and flow rate. After up to four cycles of adsorption and desorption, it was found that the adsorbent was reusable. The maximum adsorption capacities for Langmuir were 187.27, 114.29, 93.28, and 89.61 µg/g for TCM, BDCM, DBCM, and TBM, respectively. CS/CAC has a high adsorption capacity, especially for TCM, which is responsible for a major portion of THMs in drinking water. This indicates that CS/CAC has a lot of potential uses when it comes to removing THMs from water.
研究领域:
环境科学
·
水处理技术
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DOI
高影响因子
Desalination and Water Treatment
·
2016
·
IF 1.272
Xunchao Li,Cong Li,Mingda Bayier,Taotao Zhao,Tuqiao Zhang,Xinbo Chen,Xinwei Mao
Residual chlorine decay and trihalomethanes (THM) formation of desalinated seawater by ultrafiltration (UF) and nanofiltration (NF) membranes in a pilot-scale water distribution system (DWDS) were investigated. Three-dimensional fluorescent features of two source waters including NF permeate and municipal water were studied. Sixteen groups of data-sets were obtained to explore the effects of initial chlorine concentration (ICC), dissolved organic carbon (DOC), and temperature on chlorine decay and THM formation in laboratory conditions and pilot-scale DWDS, respectively. A first-order model was applied to evaluate the chlorine decay of desalinated seawater and a new model combining ICC, DOC concentration, and temperature was obtained to determine the first-order decay coefficient. Other seven models describing the kinetics of chlorine decay were also applied and compared in this study. Total trihalomethanes (TTHM) formation kinetics was studied and first-order model was suggested to describe this formation. The relationship between TTHM formation and chlorine demand was demonstrated and the results showed that second-order polynomial model better described the relationship.
研究领域:
环境科学
·
水处理工程
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DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Xiaochao Duan,Xiaobin Liao,Jianfei Chen,Shuguang Xie,Huan Qi,Fei Li,Baoling Yuan
Disinfection is an indispensable process to inactivate pathogens , while unexpected disinfection by-products (DBPs) would also be formed between the reaction of residual disinfectants and microorganisms in the water distribution system (WDS). However, there are few studies referring to the formation of DBPs and DBPs-associated toxicity under various disinfection methods based on microorganisms in the real WDS. In addition, the main contributors of bacterial communities or components that generate DBPs are unclear. In this study, the formation of trihalomethanes (THMs), halo-acetic acids (HAAs), nitrosamines (NAs) from culturable microorganisms in pipeline network by ozonation(O 3 ), chlorination (Cl 2 ), chloramination (NH 2 Cl) and joint disinfection methods were compared, meanwhile, their calculated toxicities under different oxidation scenarios were also discussed. Moreover, 16S ribosomal ribonucleic acid (rRNA) gene sequencing was used to identify the main microbial communities . The results demonstrated that THMs and HAAs increased with increasing disinfectant dosages, while the quantity of NAs (mainly nitroso dimethylamine (NDMA)) was not significantly related to disinfectant dosages for each disinfection strategy. Chloroform (TCM) and dichloroacetic acid (DCAA) were the dominant THMs and HAAs species, respectively. NDMA existed in the samples before disinfections, which may due to the metabolic activity of microorganisms. Pre-O 3 increased THMs formation during subsequent Cl 2 and NH 2 Cl treatment. However, pre-O 3 effectively reduced HAAs produced by subsequent chlorination. O 3 /Cl 2 disinfection had the highest DBPs formation potential (DBPFP) (883.6 nM), while its calculated toxicity was similar to that in Cl 2 disinfection treatment. Pseudomonas was the most abundant bacterial genus in biofilm of WDS pipeline. This study can aid in an optimal disinfection strategy for water treatment plants to reduce the toxicity of DBPs caused by biomass in pipelines and ensure water quality safety.
研究领域:
环境科学
·
微生物学
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DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）