CHEMOSPHERE
·
2021
·
IF 7.086
Guo-Qiang Li,Zheng-Yang Huo,Qian-Yuan Wu,Zhuo Chen,Yin-Hu Wu,Yun Lu,Hong-Ying Hu
Recently, ultraviolet light-emitting diodes (UV-LEDs) and chlorine combined system has been employed as an emerging advanced oxidation process . However, UV-LEDs were commonly considered as monochromatic UV sources. In this study, the obvious quantum yields of chlorine photolysis under 265 nm and 280 nm LEDs irradiations were investigated with treating LEDs as polychromatic UV sources. Particularly, Φ obs-poly of HOCl and OCl⁻ for 265 nm LED were found to be 1.50 and 0.70 mol E −1 , respectively, whereas Φ obs-poly of HOCl and OCl⁻ for 280 nm LED were 1.28 and 0.64 mol E −1 , respectively. It was identified that Φ obs-poly were 5.66–14.63 % lower than Φ obs-mono . This suggests that obvious quantum yield using peak emission wavelength would overestimate the true quantum yield. The production of radical species in LED UV/chlorine systems were determined by the degradation of BA , and illustrated by a mathematical model. Different trends were observed for 265 nm and 280 nm LED UV/chlorine systems as pH increased from 5.0 to 10.0. As pH increased, the formation of OH continuously decreased in both 265 nm and 280 nm LED systems. The formation of Cl increased at neutral pH and more Cl and OH were formed due to the higher molar absorbance coefficient at 280 nm. The chlorine dose-dependent effects on radical productions at pH of 5.0, 7.5 and 10.0 were also assessed. At pH of 5.0, OH was the main radical product and had linear correlation with chlorine dose. At pH of 7.5, the productions of OH and Cl showed similar profiles that increased rapidly at low chlorine dosage and then slowed down.
研究领域:
环境科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
Journal of Environmental Sciences
·
2022
·
IF 6.796
Lin Deng,Wei Luo,Xiao Chi,Tingting Huang,Longjia Wen,Huiyu Dong,Mingxian Wu,Jun Hu
The UV/Cl 2 process is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of high-toxic halonitromethanes (HNMs) in the presence of bromide ions (Br − ) during UV/Cl 2 disinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br − . An excessively high concentration of Br − induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor (BIF) increased, while the maximum bromine utilization factor (BUF) decreased with the increase of Br − concentration. The maximum yield of HNMs decreased as pH value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while pH value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl 2 :Br − ratio of 12.5, whereas the BIF value remained relatively higher at low Cl 2 :Br − ratios (2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon . Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation (especially brominated species) when the UV/Cl 2 process is adopted as a disinfection technique.
研究领域:
环境科学
·
公共卫生
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DOI
高影响因子
Journal of Environmental Sciences
·
2023
·
IF 6.9
Sinong Huang,Hongwei Liu,Kunming Wei,Liang Zhang,Xiaoyan Ma,Qingsong Li,Xueyan Li,Andrea M. Dietrich
As a strong oxidizing agent, ozone is used in some water treatment facilities for disinfection, taste and odor control, and removal of organic micropollutants. Phenylalanine (Phe) was used as the target amino acid to comprehensively investigate variability of disinfection byproducts (DBPs) formation during chlorine disinfection and residual chlorine conditions subsequent to ozonation. The results showed that subsequent to ozonation the typical regulated and unregulated DBPs formation potential (DBPsFP), including trichloromethane (TCM), dichloroacetonitrile (DCAN), chloral hydrate (CH), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), and trichloroacetamide (TCAcAm) increased substantially, by 2.4, 3.3, 5.6, 1.2, 2.5, and 6.0 times, respectively, compared with only chlorination. Ozonation also significantly increased the DBPs yield under a 2 day simulated residual chlorine that mimicked the water distribution system; DBPs formations followed pseudo first order kinetics. The formation rates of DBPs in the first 6 h was higher for TCM (0.214 h −1 ), DCAN (0.244 h −1 ), CH (0.105 h −1 ), TCAcAm (0.234 h −1 ), DCAA (0.375 h −1 ) and TCAA (0.190 h −1 ) than thereafter. The peak DBPsFP of TCM, DCAN, CH, TCAcAm, DCAA, and TCAA were obtained when that ozonation time was set at 5–15 min. Ozonation times > 30 min increased the mineralization of Phe and decreased the formation of DBPs upon chlorination. Increasing bromine ion (Br − ) concentration increased production of bromine- DBPs and decreased by 59.3–92.2% chlorine-DBPs formation. Higher ozone dosages and slight alkaline favored to reduce DBP formation and cytotoxicity. The ozonation conditions should optimize for all application purposes including DBPs reduction.
研究领域:
环境科学
·
水处理工程
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产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2018
·
IF 4.61
Guo-Qiang Li,Zheng-Yang Huo,Qian-Yuan Wu,Yun Lu,Hong-Ying Hu
An ultraviolet (UV)-based advanced oxidation process (AOP) for disinfecting water is introduced in this paper. This study aimed to evaluate the potential of UV light-emitting diodes (UV-LEDs)/chlorine AOP (UV/Cl 2 ) for Bacillus subtilis spore inactivation. Chlorine was combined with 265 and 280 nm LEDs (UV 265 /Cl 2 , UV 280 /Cl 2 ) and investigated. The addition of 4.0 mg/L of free chlorine at pH 7.0 in the presence of 125 mJ/cm 2 of UV irradiation resulted in an additional 1.8-log reduction in UV 265 /Cl 2 and 1.5-log reduction in UV 280 /Cl 2 . There was no observed enhancement in spore inactivation with the addition of a radical scavenger, t-BuOH, which indicated the role of • OH in the synergistic effect. To quantitatively evaluate the synergism, the primary treatment with UV/Cl 2 was followed by further UV or Cl 2 treatment. After UV/Cl 2 pretreatment at different pH levels, the 265 and 280 nm LEDs treatment enhanced an approximate 0.4–0.5-log reduction compared to UV only, and Cl 2 treatment enhanced an approximate 0.7–1.1-log reduction compared to Cl 2 only. In addition, at pH 7.0, in UV 265 /Cl 2 -Cl 2 and UV 280 /Cl 2 -Cl 2 , the inactivation rate constant k increased by approximately 2 and 1.5 times, respectively. The CT for the lag phases ( CT lag ) reduced to approximately 67 and 58%, respectively. Similar results were obtained at pH 7.5 and 8.0, and in the secondary effluent. The synergistic effect on spore inactivation suggested that the pathogen inactivation efficiency of sequential UV and chlorine disinfection processes, which are commonly applied, can be significantly enhanced by adding chlorine prior to UV treatment .
研究领域:
微生物学
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环境科学
·
水处理技术
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产品关联
DOI
PubMed
高影响因子
Journal of Cleaner Production
·
2021
·
IF 9.297
Maocai Shen,Zhuotong Zeng,Long Li,Biao Song,Chengyun Zhou,Guangming Zeng,Yaxin Zhang,Rong Xiao
As an important contributor of environmental microplastics , wastewater treatment plants have attracted extensive attention. The negative effect of suspended particulate matter on disinfection effect has also been established. The main aims of this study were to understand the potential effects of granular polyethylene microplastic and fibrous polyamide microplastics on ultraviolet and chlorine disinfection in water/wastewater treatment. In the laboratory, microplastics were exposed to different disinfection methods, which represented the disinfection dose and disinfection conditions of real water and wastewater treatment. Escherichia coli (8099) were selected as the experimental object. Microplastic suspended solids were closely related to water turbidity and UV transmittance at 254 nm. The occurrence of microplastics significantly reduced the efficiency of ultraviolet and chlorine disinfection in water/wastewater treatment, and the efficiency decreased with the increase of microplastics concentration or the decrease of disinfectant dosage. When the concentration of microplastics reached a certain level (>50 mg L −1 ), even if the exposure dose continued to increase, the disinfection efficiency could not be improved. Microplastics can reduce the concentration of disinfectants around them by reacting with disinfectants, thus protecting the microorganisms enriched on the surface of microplastics. Although the harsh conditions tested here are rarely met in a typical water treatment process, it represented a worse result. These results were intended to be used by water treatment plants to predict the effects of microplastics in the secondary effluent on UV and chlorine disinfection processes .
研究领域:
环境科学
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微生物学
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产品关联
DOI
高影响因子
Journal of Water Process Engineering
·
2024
·
IF 6.3
Ruotong Xu,Xiuneng Zhu,Keshu Sheng,Yulin Tang,Yongji Zhang
The presence of Viable but nonculturable (VBNC) bacteria in drinking water distribution systems(DWDS)which can recover and regain pathogenicity under certain conditions, leads to a serious underestimation of the number of microorganisms in the water and consequently microbiological risks. This study investigated E. coli's biofilm integrity and metabolic activity post‑chlorine disinfection and during resuscitation in a Circulating-flow Dynamic biofilm Contactor (CDC) reactor. Chlorine rapidly induced the VBNC state, with concentrations ≥0.3 mg/L causing all respiratory-active bacteria to transition. Higher chlorine levels damaged cell biofilms, reducing intact cell counts by 95 % and depleting ATP. VBNC bacteria in biofilms quickly regained culturability, utilizing available nutrients and ATP. Within 1–4 days, culturable bacteria in the biofilm increased from 2.29 to 4.95 log CFU/mL, significantly faster than in water. This growth corresponded with rising ATP levels, though slower than in aqueous environments. Signaling molecules (C6, C8, C12, C14) regulated gene expression during resuscitation, aiding bacterial recovery and proliferation. Chlorine disinfection disrupted intercellular communication, altering VBNC bacteria's physiological and metabolic characteristics. These findings highlight the complex dynamics of VBNC bacteria in water systems, their resuscitation potential, and the importance of biofilms in bacterial recovery, emphasizing the need for comprehensive water treatment strategies.
研究领域:
微生物学
·
环境卫生学
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产品关联
DOI
高影响因子
ENVIRONMENTAL GEOCHEMISTRY AND HEALTH
·
2024
·Vol. 46
·期 2
·1-13
·
IF 3.2
Wang Tao,Deng Lin,Dai Wenjuan,Tan Chaoqun,Hu Jun,Singh Rajendra Prasad
Brominated halonitromethanes (Br-HNMs) are generated in water disinfection processes and present high toxicity to human health. This work used aspartic acid (ASP) as the precursor to reveal that bromide (Br − ) induced the production of Br-HNMs in the UV/chlorine disinfection process. Consequently, six Br-HNMs were identified, and their yields presented an increasing and then declining evolution over the reaction time from 0 to 15 min. Also, the total Br-HNMs yield reached the maximum of 251.1 μg L −1 at 5 min and then declined to 107.1 μg L −1 . The total Br-HNMs yield increased from 2.40 to 251.14 μg L −1 with the increase of Cl 2 :Br − ratios from 0.25 to 3.0 by increasing free chlorine dosage with a fixed Br − concentration, and it increased from 207.59 to 251.14 μg L −1 and then decreased to 93.44 μg L −1 with the increase of Cl 2 :Br − ratio from 1.0 to 3.6 by increasing Br − concentration with a fixed free chlorine dosage. Besides, the total Br-HNMs yield reached the highest value (251.14 μg L −1 ) at pH 7.0 and the lowest value (74.20 μg L −1 ) at pH 8.0. Subsequently, the possible reaction mechanism of Br-HNMs generated from ASP was deduced, and the changes in toxicity of Br-HNMs also followed an increasing and then declining trend, closely relating to Br-HNMs yields and Br − utilization. This work explored and illustrated the yields, influence factors, reaction mechanisms, and toxicity of Br-HNMs formed from Br − containing ASP water during UV/chlorine disinfection, which might help to control Br-HNMs formation.
研究领域:
环境科学
·
水处理工程
·
毒理学
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产品关联
DOI
PubMed
高影响因子
WATER RESEARCH
·
2019
·
IF 7.913
Ze-Chen Gao,Yi-Li Lin,Bin Xu,Ying Xia,Chen-Yan Hu,Tian-Yang Zhang,Tong-Cheng Cao,Wen-Hai Chu,Nai-Yun Gao
The efficiency of the ultraviolet (UV)/chlorine process strongly depends on UV wavelength because chlorine photolysis and its subsequent radical formation are highly wavelength-dependent. This study compared the degradation of humic acid (HA) during the UV/chlorine process by low pressure mercury lamp (LPUV, 254 nm) and ultraviolet light-emitting diode (UV-LED, 275 and 310 nm). The results indicated that HA degradation followed the pseudo-first-order kinetics, and the fluence-based degradation rate constants ( k obs ) were significantly affected by UV wavelength and solution pH. HA degradation decreased greatly with increasing solution pH during the UV/chlorine process at 254 nm, while the opposite trend was observed at 275 and 310 nm. In the meantime, k obs decreased in the order of 275 nm > 254 nm > 310 nm at pH > 7.0. The changes of chlorine molar absorption coefficients at different UV wavelengths resulted in the variation of chlorine photodecay rates ( k obs, chlorine ), and the synergistic effects of k obs, chlorine and chlorine quantum yields (Φ chlorine ) affected HA reduction. The formation of disinfection by-products (DBPs) during the UV/chlorine process was also evaluated. A significant suppression on DBP formation and DBP-associated calculated theoretical cytotoxicity were observed at 275 nm high UV fluence and alkaline pHs. These findings in this study demonstrate that UV wavelength at 275 nm is more suitable for HA degradation by the UV/chlorine advanced oxidation process in practical applications.
研究领域:
环境科学
·
水处理工程
·
化学工程
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产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2023
·
IF 9.8
Jiafu Li,Jingsi Chen,Zengli Zhang,Xiaojun Liang
To prevent the reactions of disinfection byproducts (DBPs) or natural organic matters with residual chlorine in drinking water in the course of the water store, residual chlorine is quenched by chlorine quenchers, while some chlorine quenchers may result in dechlorination of DBPs. Phenolic compounds are a group of highly toxic DBPs compared to regulated aliphatic DBPs (trihalomethanes (THMs) and haloacetic acids (HAAs)), which might be a great threat to drinking water safety. Nevertheless, impact of popular chlorine quenchers on phenolic DBPs is less understanding. In this study, the influences of ammonium chloride , ascorbic acid , sodium thiosulfate , and sodium sulfite on phenolic DBPs are assessed. Total concentration of 19 phenolic DBPs in drinking water from 7 Chinese cities was 145–1821 ng/L, suggesting a widely occurrence of these pollutants. Four assessed chlorine quenchers have not impacts on mass spectra of studied phenolic DBPs. Additionally, when the storage time ≤24 h, recoveries of 19 phenolic DBPs using four assessed chlorine quenchers are within the accept levels (70–130 %). However, when the storage time increased to 168 h, ascorbic acid and sodium thiosulfate satisfied the recovery requirement of phenolic DBPs during the sample analysis, and ammonium chloride and sodium sulfite showed a unacceptable impact on bromo-chloro-phenols. In general, ascorbic acid and sodium thiosulfate are recommended to be the ideal chlorine quenchers of phenolic DBPs. Mechanism study indicated that sodium sulfite induced the dechlorination of 2-chloro-4-bromophenol via nucleophilic reaction. This study is the first attempt to provide the impact of chlorine quenchers on phenolic DBPs and corresponding reaction mechanism.
研究领域:
环境科学
·
公共卫生
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产品关联
DOI
PubMed
高影响因子
Journal of Environmental Sciences
·
2024
·
IF 5.9
Shuang Chen,Yue Qiao,Youwei Jiang,Wei Qiu,Shuang Zang,Jing Zhang,Xianshi Wang,Jun Ma
Halogenated aromatic disinfection byproducts (DBPs) are gradually receiving attention due to their high detection frequency and usually higher toxicity than regulated DBPs. In this study, we established a solid phase extraction (SPE)-LC-MS/MS method to simultaneously trace analyze 59 halogenated aromatic DBPs. The limits of detection and limits of quantification of halogenated aromatic DBPs ranged from 0.03 ng/L to 135.23 ng/L and 0.1 ng/L to 450.76 ng/L, respectively. The range of recoveries and relative standard deviation (RSD) in river water were between 72.41 % to 119.54 % and 1.86 % to 16.03 %, respectively. Therefore, this method can be used to accurately analyze trace levels of halogenated aromatic DBPs in drinking water. The occurrence and transformation of halogenated aromatic DBPs were explored based on this method. In the chlorinated simulated source water and chlorinated river water, 20 and 45 halogenated aromatic DBPs were determined, respectively. The active halogen species (HOCl, HOBr, and HOI) first reacted with natural organic matter (NOM) to form halogenated aromatic DBPs. Then, chlorine further reacted with the halogenated aromatic DBPs to convert them into small-molecule halogenated aliphatic DBPs through oxidation, electrophilic substitution, and hydrolysis reaction, etc. In the chlorinated simulated source water, chlorinated river water, and tap water, the toxicity contribution of bromoacetic acids (Br-HAAs) accounted for the majority (> 71.16 %). Given that halogenated aromatic DBPs are intermediate products of halogenated aliphatic DBPs, controlling the formation of halogenated aromatic DBPs is beneficial in decreasing the formation of halogenated aliphatic DBPs, thereby diminishing the toxicity of drinking water.
研究领域:
环境科学
·
分析化学
·
公共卫生
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产品关联
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Chuyin Qiu,Weiting He,Yu Li,Feng Jiang,Yang Pan,Meihui Zhang,Daying Lin,Kaili Zhang,Yanduo Yang,Wen Wang,Pei Hua
Chlorine disinfection is widely applied in drinking water treatment plant to inactivate pathogens in drinking water , but it unintentionally reacts with organic matter present in source waters and generates halogenated disinfection byproducts (DBPs). Sugar is one of the most commonly used seasoning in our diet. The addition of sugar could significantly improve the taste of the beverages; however, the effects of sugar on DBP formation and transformation remain unknown. In this study, the effects of sugar type and dose on the halogenated DBP formation in chlorinated boiled real tap water were evaluated during making hot beverages. We found that sugar can react with chlorine residual in tap water and generate halogenated DBPs. As the most commonly used table sugar, the addition of sucrose in the water sample at 100 or 500 mg/L as C could increase the level of total organic halogen (TOX) by ∼35%, when compared with the boiled tap water sample without sugar addition. In addition, fifteen reported and new polar brominated and chlorinated DBPs were detected and proposed from the reaction between chlorine and sucrose; accordingly, the corresponding transformation pathways were also proposed. Moreover, the DBP formation in the chlorinated boiled real tap water samples with the addition of xylose , glucose, sucrose, maltose and lactose were also investigated. By comparing with the TOX levels in the water samples with different sugar addition and their calculated TOX risk indexes, it was suggested that applying xylose as a sweetener in beverages could not only obtain a relatively high sweetness but also minimize the adverse effect inducing by halogenated DBPs during making hot beverages.
研究领域:
水处理
·
环境化学
·
食品科学
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DOI
PubMed
高影响因子
Journal of Cleaner Production
·
2022
·
IF 11.072
Yanan Shao,Xiaodong Li,Longbo Jiang,Xue Wei,Yanlan Zhao,Xuwu Chen,Shuai Li
UV/chlorine as an advanced oxidation process (AOPs) has been employed to treat contaminants. However, current research has primarily focused on drinking water and sewage treatment . This paper investigated the degradation of ciprofloxacin (CIP) by UV/chlorine treatment in hospital urine components that contain a higher concentration of iodine (I − ). The results indicated that the characteristic ions (HCO 3 − , SO 4 2− , and NH 4 + ) and I − in hospital urine inhibited CIP removal. In contrast, the characteristic ion, Cl − ion promoted this degradation reaction. Surprisingly, microgram levels of I − strongly inhibited CIP degradation. The characteristic ions can reduce the contribution of hydroxyl radicals (HO•) and reactive chlorine species (RCS). I − can decrease the contribution rate of HO• while slightly increasing the contribution of other radical oxidation in phosphate buffer solution (PBS) ascribed to the formation of HOI and reactive iodine species (RIS). Three degradation pathways have been proposed based on the main transformation products : hydroxylation , electron transfer , and halogen substitution. The piperazine ring of CIP was the main reactive group, and the N2, C10, C16, and C13 atoms were identified as reaction sites. Preliminary toxicity analysis suggested that the toxicity of hospital hydrolyzed urine containing iodine was higher than that of PBS.
研究领域:
环境科学
·
水处理
·
化学工程
·
毒理学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）