Formation of chlorinated disinfection by-products in viticulture

Background, aim and scope  The use of sodium hypochlorite (HYP) in viticulture results in effluents which are contaminated with halogenated substances. These disinfection by-products (DBPs) can be quantified as group parameter ‘adsorbable organic halogens’ (AOX) and have not been determined in effluents of viticulture yet. The substances that are detected as AOX are unknown. The AOX can be composed of harmless substances, but even toxic contaminants. Thus, it is impossible to assess ecological impacts. The aim of this study is to determine the quantification of AOX and DBPs after the use of HYP. This will be helpful to reduce environmental pollution by AOX. Materials and methods  The potential of HYP to generate AOX was determined in laboratory-scale experiments. Different model solutions were treated with HYP according to disinfection processes in viticulture and conditions of AOX formation in effluents were simulated. AOX were quantified using the flask-shaking method and identified DBPs were investigated by gas chromatography–mass spectrometry. Results  Treatment with HYP resulted in the formation of AOX. The percentage conversion of HYP to AOX was up to 11%. Most important identified DBPs in viticulture are chloroform, dichloroacetic acid and trichloroacetaldehyde. In addition, the formation of carbon tetrachloride (CT), 1,1,1-trichloropropanone, 2,4-dichlorobenzoic acid and 2-chloro-/2,4-dichlorophenylacetic acid was investigated. It was demonstrated that reaction temperature, concentration of HYP and type of organic matter have important influence on the formation of chlorinated DBPs. Discussion  The percentage conversion of HYP to AOX was similar to other published studies. Although a correlation of single compounds and AOX is difficult, chloroform was the predominant AOX. Generation of the volatile chloroform should be avoided due to possible adverse effects. The generation of dichloroacetic acid is of minor importance on account of biodegradation. Trichloroacetaldehyde and 1,1,1-trichloropropanone are weak mutagens and their formation should be avoided. Conclusions  The generation of AOX and chlorinated DBPs can be minimised by reducing the concentrations of the organic materials in the effluents. The removal of organic matter before disinfection results in a decreased formation of AOX. HYP is an effective disinfectant; therefore, it should be used at low temperatures and concentrations to reduce the amount of AOX. If possible, disinfection should be accomplished by the use of no chlorine-containing agents. By this means, negative influences of HYP on the quality of wine can also be avoided. Recommendations and perspectives  Our results indicate that HYP has a high potential to form AOX in effluents of viticulture. The predominant by-products are chloroform, dichloroacetic acid and trichloroacetaldehyde. In further research, wastewaters from a winery and the in- and outflows of two sewage treatment plants were sampled during vintage and analysed. These results will be discussed in a following paper.     

Exposure to inhaled THM: Comparison of continuous and event-specific exposure assessment for epidemiologic purposes

Trihalomethanes (THMs) (chloroform, bromoform, dibromochloromethane, and bromodichloromethane) are the most abundant by-products of chlorination. People are exposed to THMs through ingestion, dermal contact and inhalation. The objective of this study was to compare two methods for assessing THM inhalation: a direct method with personal monitors assessing continuous exposure and an indirect one with microenvironmental sampling and collection of time–activity data during the main event exposures: bathing, showering and swimming. This comparison was conducted to help plan a future epidemiologic study of the effects of THMs on the upper airways of children. 30 children aged from 4 to 10 years were included. They wore a 3M^™ 3520 organic vapor monitor for 7 days. We sampled air in their bathrooms (during baths or showers) and in the indoor swimming pools they visited and recorded their time–activity patterns. We used stainless steel tubes full of Tenax^® to collect air samples. All analyses were performed with Gas Chromatography and Mass Spectrometry (GC-MS). Chloroform was the THM with the highest concentrations in the air of both bathrooms and indoor swimming pools. Its continuous and event exposure measurements were significantly correlated (r_s = 0.69 p < 0.001). Continuous exposures were higher than event exposures, suggesting that the event exposure method does not take into account some influential microenvironments. In an epidemiologic study, this might lead to random exposure misclassification, thus underestimation of the risk, and reduced statistical power. The continuous exposure method was difficult to implement because of its poor acceptability and the fragility of the personal monitors. These two points may also reduce the statistical power of an epidemiologic study. It would be useful to test the advantages and disadvantages of a second sample in the home or of modeling the baseline concentration of THM in the home to improve the event exposure method.     

Effect of NOM characteristics on brominated organics formation by ozonation

In this study, organic fractions, namely, humic acid, fulvic acid, hydrophobic base and neutral, and hydrophilic acid, base, and -neutral, were extracted from source water. First, the characteristics of the organic fractions, such as carboxylic acidity, phenolic acidity, ultraviolet absorbance, and aromatic content, were analyzed. Further, a systematic study was carried out to the by-products obtained when organic fractions, to which various amounts of bromide had been added, were oxidized with ozone. Samples after ozonation were analyzed for several brominated organics. The results indicate that the characteristics of the aquatic organic matter, including carboxylic/phenolic acidity, aromatic/aliphatic content, and ultraviolet absorbance, appear to affect the formation of halogenated organics. In general, hydrophobic organics having higher phenolic acidity, aromatic content, and ultraviolet absorbance have higher ozone consumption and produce higher concentrations of brominated organics than hydrophilic organics. It was also found that humic acid demonstrated the highest bromoform (CHBr(3)), dibromoacetic acid (DBAA), and 2,4-dibromophenol (2,4-DBP) formation, whereas hydrophilic neutral produced less CHBr(3) and 2,4-DBP than the rest of the organic fractions but produced the highest amount of dibromoacetone (DBAC) and dibromoacetonitrile (DBAN).     

催化剂填料表面微生物对微污染物胁迫的响应

目前复合微污染水源条件下,饮用水中复合微污染物对微生物带来的胁迫效应会引发含氮类消毒副产物生成势(nitrogenous disinfection byproducts formation potential, N-DBPs FP)和抗性基因(antibiotic resistance genes, ARGs)水质风险。本研究基于催化剂(HCLL-S8-M)作为新型生物滤料建立反应器处理砂滤后水,考察生物滤池出水N-DBPs FP和ARGs丰度,对滤料胞外聚合物(extracellular polymeric substance, EPS)进行分析,通过宏基因组学分析水体中微生物群落结构和胁迫效应基因表达水平。结果表明,在相同复合微污染物条件下(磺胺嘧啶和2,4-二氯苯氧乙酸各1 µg·L⁻¹),HCLL-S8-M滤柱出水中卤代乙腈和卤代硝基甲烷的总生成势为522.30 ng·L⁻¹,比椰壳活性炭滤柱出水低171.70 ng·L⁻¹,ARGs相对丰度也比椰壳活性炭滤柱出水低约4倍。这得益于HCLL-S8-M滤柱可以高效去除包括微污染物在内的溶解性有机碳、SUVA和高分子质量的有机物。HCLL-S8-M滤柱和出水中微生物分泌更少的EPS,从而减少的N-DBPs前驱体和削弱ARGs的水平转移。宏基因组学分析结果表明,微生物在HCLL-S8-M滤柱出水中的氧化应激反应功能基因表达比椰壳活性炭滤柱下降。HCLL-S8-M滤柱减弱微污染物对微生物的胁迫效应,降低N-DBPs FP和ARGs,有助于控制微生物应激反应造成间接饮用水水质风险。     

溶解性有机物与活性氯物种反应过程中其分子组成对消毒副产物生成的影响

溶解性有机物(DOM)在紫外/氯(胺)高级处理过程中会与活性氯物种(Cl^•和Cl₂^•−)反应生成消毒副产物(DBPs),进而影响水质的毒性和安全性。本研究详细研究了单一活性氯物种(Cl^•或Cl₂^•−)与不同来源DOM反应生成DBPs的情况,重点探究了DOM分子组成与生成DBPs质量浓度、种类、毒性之间的相关关系。结果表明：Cl^•与DOM反应过程中主要生成的DBPs及毒性贡献者分别为三卤甲烷(THMs)和卤乙醛(HALs)。DOM的分子组成与生成DBPs的质量浓度、种类及毒性之间相关性较低,这可能归因于Cl^•与不同DOM之间相似的反应活性,而在Cl₂^•−与DOM反应过程中HAAs和非管制类DBPs分别为主要生成的DBPs和毒性贡献者。此外,生成DBPs的质量浓度、种类及体系的毒性与DOM分子的不饱和度、芳香度、含氧量、极性呈负相关,与DOM中含N、S、P官能团化合物的相对含量呈正相关。本研究推动了DOM在单一活性氯物种介导下生成DBPs的研究,并为高级氧化工艺参数的优化及高毒性副产物的消减提供依据。     

长距离调水水源中溶解性有机物特征及消毒副产物生成势的变化解析

水体中溶解性有机物(dissolved organic matter, DOM)是消毒副产物的重要前体物,本研究考察了季节变化对长距离输水干渠中DOM特征及消毒副产物生成势(disinfection by-products formation potential, DBPsFP)的影响。发现类芳香蛋白和类富里酸是主要荧光类物质,而夏季类可溶性微生物产物组分的比例显著上升,且自生源指标表明夏季样本具有更强的内源特性。体积排阻色谱耦合有机碳检测器(high-performance size exclusion chromatography coupled with an organic carbon detector, HPSEC-OCD)分析显示输水过程中水质稳定,腐殖质(humic substances, HS)组分在总有机碳中所占比例超过60%,而分子质量大于20 kDa的生物大分子聚合体(biopolymers, BP)在夏季有所增加。不同季节DOM的氯反应活性也不同,夏季反应性更强,导致更高的DBPsFP。夏季温度升高,间接促进浮游生物繁殖和微生物活动,进而改变了DOM的组成结构和反应性。此外,由于HPSEC-OCD几乎可以表征所有类型的有机碳,因此它所表征的组分与DBPsFP的相关性更好,其中三卤甲烷生成势与BP组分呈高度正相关,卤乙酸生成势则与HS组分关联更紧密。了解DOM的时空变化特征及其与DBPsFP的相互关系,将有助于更好地优化水处理方法以获得更稳定的水质。     

饮用水中高分子量消毒副产物的检测识别方法

消毒是饮用水处理过程中的重要步骤,但普遍采用的氯系消毒剂在杀灭细菌病毒的同时,能产生大量具有“三致”效应的卤代消毒副产物（DBPs）,严重威胁了饮用水的化学安全. 研究人员已在饮用水中陆续检测并识别出700多种DBPs,但这些已知DBPs均为分子量小于800 Da的低分子量DBPs,目前对高分子量DBPs的认识还较为有限. 本研究建立了基于基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）的高分子量DBPs检测方法,发现在基质为2,5-二羟基苯甲酸,阳离子化试剂为三氟乙酸钠,使用三明治法点靶,反射-正离子模式,90%激光强度时,信噪比和信号重现性达到最优,信噪比之和达到了136.2,变异系数（CV）则为4.77%. 利用上述方法,在模拟饮用水中检测到5种新的高分子量DBPs. 在此基础上,通过同位素模式分析、TOF/TOF串联质谱和数据库验证,建立了针对未知高分子量DBPs的分子式/结构式识别方法,确定新的高分子量DBPs为寡糖羧酸类物质.     

鱼油氯胺消毒过程中溴代和碘代含氮消毒副产物的生成

本研究采用鱼油作为模拟化合物,模拟微污染原水中广泛存在的生物源有机物的脂肪类组成成分,考察氯胺消毒过程中溴代和碘代含氮消毒副产物(nitrogenous disinfection by-products,N-DBPs)的生成情况. 结果表明,鱼油经氯胺消毒后,生成的溴代和碘代N-DBPs主要包括一溴乙腈(bromoacetonitrile,BAN)、二溴乙腈(dibromoacetonitrile,DBAN)、一溴硝基甲烷(bromonitromethane,BNM)、一碘乙腈(iodoacetonitrile,IAN). 其中,在本研究考察范围内,BAN、DBAN与BNM的生成量会随溴离子和总有机碳(Total Organic Carbon,TOC)浓度的增加而增加;当溴离子浓度为5 mg·L⁻¹,TOC为20 mg·L⁻¹时,BAN、DBAN与BNM的最大生成量分别为71.15、192.36、27.52 μg·L⁻¹. IAN的生成量则随碘离子和TOC浓度的增加而增加;当碘离子浓度为0.5 mg·L⁻¹,TOC为20 mg·L⁻¹时,IAN的最大生成量为106.95 μg·L⁻¹. 当氯胺的投加量从5 mg·L⁻¹增加到100 mg·L⁻¹时,BAN、DBAN、BNM与IAN的生成量分别从4.62、33.75、3.75、10.29 μg·L⁻¹增加到49.69、218.40、22.34、123.44 μg·L⁻¹. 4种N-DBPs的生成量均随消毒时间的延长而增加,在消毒72 h后,4种N-DBPs的生成量均达到最大值. 3种卤乙腈类N-DBPs（BAN、DBAN与IAN）的生成量均随初始pH的增加呈现出先增加后减少的趋势,而BNM的生成量则随初始pH的增加而不断减少.     

INACTIVATION OF GIARDIA MURIS CYSTS BY CHLORAMINES1

ABSTRACT: In a study to measure the efficacy of chioramines at inactivating Giardia cysts, the ability of cysts to excyst was measured after exposure to different concentrations of chloramines, for different times, and at different temperatures and pH. The chloramines were generated by mixing ammonium sulfate and sodium hypochlorate in water to approximate a 7:1 chlorine:ammonia ratio by weight. Times of 40, 80, 180, and 270 minutes; temperatures of 3, 10, and 18°C; target chioramine concentrations of 0.4, 1.4, 2.0, and 2.6 mg/L; and pH of 7.0 and 8.5 were the actual values tested. The combinations of these variables that were able to inactivate >99.8 percent of the cysts were a minimum chloramine concentration of 2.26 mg/L applied for 270 minutes at a water temperature of 10°C; and at 18°C, averaged minimum chloramine concentrations of 2.14 and 1.55 mg/L applied for 180 and 270 minutes, respectively. The minimum CT values corresponding to these combinations capable of >99.8 percent cyst inactivation, are 610 at 10°C and 385 at 18°C. Temperature was noted to exert a major effect on the ability of chloramines to inactivate cysts. Modifications of the methods used to generate chloramines may have an effect on the capacity of this disinfectant to inactivate cysts.     

医院废水中耐药菌与耐药基因分布、传播及消毒技术的研究进展

世界卫生组织提出,细菌耐药性及其在环境中的传播已经成为21世纪公共卫生与环境安全的重要挑战. 医院作为抗菌药物使用的主要场所,也是耐药菌（antibiotic resistant bacteria ,ARB）和耐药基因（antibiotic resistance genes,ARGs）产生与传播的重要源头. 医院废水作为临床ARB和ARGs向环境扩散的关键媒介,对人类健康构成了严重威胁. 虽然有关医院废水中ARB和ARGs的研究已相对较多,但目前医院废水中ARB和ARGs的分布、传播以及消毒技术对其的影响等认知尚不够全面. 本文综述了医院废水中耐药菌和耐药基因的分布特征及其潜在的传播途径和公共卫生风险,概述了膜生物反应器、化学消毒（氯/臭氧消毒）、紫外线消毒、芬顿技术/光芬顿技术、光催化技术、电化学氧化技术等消毒技术对医院废水中ARB和ARGs的影响,以期为医院废水中ARB和ARGs污染的防控提供参考.