Disinfection Byproducts and Their Precursors in Drinking Water Sources:Origins,Influencing Factors,and Environmental Insights

Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as they tend to be laborious,time-consuming,or technically difficult.Disinfection byproducts(DBPs)are a family of well-known secondary pollutants formed by the reactions of chemical disinfectants with DBP precursors during water disinfection treatment.Since DBP precursors have various origins(e.g.,natural,domestic,industrial,and agricultural sources),and since the formation of DBPs from different precursors in the presence of specific disinfectants is distinctive,we argue that DBPs and DBP precursors can serve as alternative indicators to assess the contamination in water sources and identify pollution origins.After providing a retrospective of the origins of DBPs and DBP precursors,as well as the specific formation patterns of DBPs from different precursors,this article presents an overview of the impacts of various natural and anthropogenic factors on DBPs and DBP precursors in drinking water sources.In practice,the DBPs(i.e.,their concentration and speciation)originally present in source water and the DBP precursors determined using DBP formation potential tests—in which water samples are dosed with a stoichiometric excess of specific disinfectants in order to maximize DBP formation under certain reaction conditions—can be considered as alternative metrics.When jointly used with other water quality parameters(e.g.,dissolved organic carbon,dissolved organic nitrogen,fluorescence,and molecular weight distribution)and specific contaminants of emerging concern(e.g.,certain pharmaceuticals and personal care products),DBPs and DBP precursors in drinking water sources can provide a more comprehensive picture of water pollution for better managing water resources and ensuring human health.

Combination of chlorine and magnetic ion exchange resin for drinking water treatment of algae

The effectiveness of a magnetic ion exchange resin （MIEX） for the treatment of Hongze Lake water in China was evaluated, The kinetics of natural organic matter （NOM） removal at various MIEX doses and contact time, multiple-loading experiments, impacts of MIEX prior to coagulation on coagulant demands and the effectiveness of combination of MIEX, pre-chlorination and coagulation were investigated. Kinetic experimental results show that more than 80% UV254 and 67% dissolved organic carbon （DOC） from raw water can be removed by the use of MIEX alone. 94% sulfate, 69% nitrate and 98% bromide removals are obtained after the first use of MIEX in multiple-loading experiments. It is suggested that MIEX can be loaded up to 1 250 bed volume （BV, volume ratio of tested water to resin） or more without saturation when regarding organics removal as a target. MIEX can remove organics to a greater extend than coagulation and lower the coagulant demand when combining with coagulation. Chlorination experimental results show that MIEX can remove 57% chlorine demand and 77% trihalomethane formation potential （THMFP） for raw water. Pre-chlorination followed by MIEX and coagulation can give additional organic and THMFP removals. The results suggest that MIEX provides a new method to solve thc problem algae reproduction.

The Disinfection of Drinking Water in Trunk Water Mains

This study aimed to explore the disinfection of drinking water in trunk water mains, based on published conditions denoted within the Irish Republic. The variables within the study were consumer draw-off rates, trunk main length, pipe diameter, and water temperature. All these factors are known to impact the free chlorine residual in operational supply networks. Based on published conditions obtained within the literature review, 60 hypothetical trunk mains were generated for this study. Of primary concern were the variables that affect the chlorine decay rate;total amount of chlorine decay;available amount of chlorine in the periphery of the trunk main;and the costs associated with effective chlorine disinfection of trunk mains. Based on the analysis performed, the following were the salient observations: 1) Low consumer draw-off rates and increased trunk main length and diameter increased the risk of the free chlorine residual in the periphery of the trunk mains not complying with the Environmental Protection Agency’s (EPA) minimum recommended residual value of 0.1 mg/l (EPA Drinking Water Audit Report, 2014). 2) Increasing the diameter of the trunk main from 125 mm to 180 mm had a negligible effect on the chlorine decay rate. However, increasing the trunk main diameter from 125 mm to 180 mm was shown to have a major impact on the total amount of chlorine decay and free chlorine residual available in the periphery of the main. The key parameters that affected disinfection costs associated with trunk mains include length, diameter and the need for chlorine boosting.

Design of Water Disinfection Scheme for Rural Drinking Water Safety Project

As further promotion of the rural drinking water safety project in whole country, small villages in vast countryside have been or will be equipped with safety drinking water project. We analyzed necessity of the rural drinking water disinfection, discussed disinfection method suitable for rural drinking water characteristics, and put forward disinfection schemes for different water supply sources.

Comparison of Anolyte and Chlorine Dioxide for a Continuous Hot Water Disinfection in Nursing Home: A Two Years Legionnaires’ Disease Prevention

Worldwide epidemiological reports assert that drinking water is a source for infections and Legionella control represents a critical issue in healthcare settings. Chemical disinfections of water networks are control measures that need to be fine-tuned to obtain satisfactory results in large buildings over prolonged time periods. Aim of study is the evaluation of the effect of anolyte and chlorine dioxide, applied in two different hot water networks of a nursing home to manage Legionella risk. Nursing home has two buildings (A and B), with the same point of aqueduct water entrance. From June 2016, following a shock chlorination, the continuous disinfections with chlorine dioxide and anolyte were applied in hot networks of building A and B, respectively. Hot water was sampled at the central heating system and at two points of use for Legionella research, while chemical tests of manganese (Mn), iron (Fe), zinc (Zn) and trihalomethanes compounds (THM) were implemented to evaluate the disinfection by-products presence. Before chlorination Legionella pneumophila sg1 was recovered with a mean count of 2.4 × 104 CFU/L, while chemical compounds concentrations were within the law limits (Directive 98/83/EC). Then the disinfections Legionella was not recovered in both hot water plants. After the disinfection with chlorine dioxide (from June 2016 to May 2018), a statistically significant increase of iron, zinc and THM concentrations was detected in building A (p = 0.012;p = 0.004;p = 0.008). Both disinfectants appear effective against Legionella spp. growth in water network, but anolyte ensures a lower disinfection by-products release.

Occurrence of Haloacetic Acids in Drinking Water in Certain Cities of China

Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinking water of the nation. Method HAAs were analyzed using gas chromatography with electron capture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Five main cities in different areas of China were chosen in the survey. Results Studies showed that the main species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 礸/L to 12.85 礸/L and from 0.56 礸/L to 10.98 礸/L, respectively. MBAA and DBAA were also detected in one city, ranging from 2.20 礸/L to 4.95 礸/L and 1.10 礸/L to 2.81 礸/L, respectively. Therefore, the contents of HAAs varied, usually no more than 25 礸/L. Based on the acquired data to date, it is known that the concentrations of HAAs in drinking water in China were surely under the limits of Sanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey of HAAs in drinking water should be conducted throughout the nation to get adequate data and information, the ultimate aim of which is to control HAAs pollution and keep the balance between microbiological safety insurance and chemical risk control, minimize the formation of DBPs and ensure the safety of water supply at the same time.

A Study on the Microbial Quality of Drinking Water in Rural Areas of Mazandaran Province in North of Iran (2011)

Backgrounds: One of the fundamental needs of a community is to have an access to healthy and safe drinking water. The lack of a concentrated accessibility to health facilities and services is among the serious problems facing villagers in the rural areas. The aims of this research was to investigate the drinking water quality of the villages in Babol township suburbs in north of Iran. Materials and Methods: In this cross-sectional descriptive study, a total of 140 water samples were taken from the water distribution network in16 villages for the low and high-rain seasons in sterile glass bottle. The microbial quality of gathered samples were determined based on standard methods in laboratory. Statistical analysis of the results was performed using a SPSS16 statistical software. Findings: Based on obtained results 13.6% of the samples were contaminated to coliform and 20% to fecal coliform bacteria. The residual chlorine in 12.5% of the samples were between 0.2 to 0.8 mg·L-1 and the PH in total samples were between 6.8 to 7.8. There were no signs of any contamination for 32.86% of the analysed samples which water resources is located to a distance of more than 30 m to the contamination sources. In addition, 43.1% of the samples taken from the water resources with no plumbing system, have had a fecal contamination. Conclusions: Considering the results achieved, the microbial quality of the drinking water of the studied villages classified as “moderate” status. For more water supply there is not sufficient residual chlorine in most cases. Poor sanitation of water supply is most causes of water contamination. It is therefore strongly recommended that sanitation measures are made to protect water resources from the contamination.

Testing the Efficiency of Acacia Bark (Galool-Asal) as Disinfectant for Polluted Waters

Acacia bark efficiency for disinfecting polluted water for the purpose of using it for drinking purposes was tested. Five polluted water samples were collected from different locations in Jordan, namely, King Abdullah Canal, an Agricultural pond in the Jordan Valley, Yajouz wells, Hazeir spring, and Wadi-Seer spring. Different volumes of the water samples were treated with 10 g of the shredded acacia bark (obtained from Somalia) for different retention times. The volumes used were 1 L, 2.5 L, and 5 L and the detention times were 2, 4, and 24 hours. The samples were tested for total coliform, E. coli, electrical conductivity, pH, total dissolved solids, turbidity and color before and after treatment with the acacia bark. Results revealed that the optimum conditions for disinfection were: 1 L polluted water treated with 10 g acacia bark for 24 hours. Log removals of about 2.5 for E. coli were obtained under these conditions. Higher removals could be achieved by using larger amounts of the acacia bark, but the chemical water quality regarding turbidity and color will not be suitable for drinking purposes and levels of tannic acids present in the acacia bark might reach toxic levels. Toxic levels will not be reached if 1 glass of water/kg body weight every 4 - 5 hours daily is consumed.

Comparative Analysis of Chemical, Physical and Biological Contaminants in Drinking Water in Various Developed Countries around the World

Sustaining a reliable and contaminant-free drinking water is becoming an increasing challenge worldwide due to human activity, industrial waste, and agricultural overuse. Surface water is the main source of drinking water around the world. However, groundwater is also becoming increasingly popular, due to its clarity and minimal need for processing to reduce turbidity. Over the years, the demand and growth in the agricultural industry has also been the means of groundwater contamination. Due to the health burden that raw water can pose, water must be processed and purified prior to consumption. Raw water quality can be compromised by physical, chemical (heavy metals and disinfection by-products), and biological contaminants. Biological contaminants can significantly impact immunocompromised populations, while chemical contaminants can impact the growth and development of young children. Although obtaining a steady and high-quality water flow to the general population is an increasing challenge, developed countries have utilized state-of-the-art technologies and techniques to provide contaminant-free water to their citizens. This research aims to provide information about the regulatory parameters, characteristics, and sources of safe drinking water in the world as a model for future use in the developing world. In this, secondary data was used to compare and contrast drinking water quality among countries in the European Union, the United States, Canada, the United Kingdom, Singapore, New Zealand, Australia, Qatar, and the United Arab Emirates. The data indicates that Ireland and the United Kingdom have relatively lower amounts of contaminants in their drinking water. Upon completing this research, it is recommended that countries desiring clean drinking water systems should initiate and invest in programs that control and protect treatment plants, water distribution systems, water sources, and catchments.

Low-Cost Sustainable Technologies for the Production of Clean Drinking Water—A Review

Water has always been an important and life-sustaining drink to humans and is essential to the survival of all known organisms. Over large parts of the world, humans have inadequate access to drinking water and use water contaminated with disease vectors, pathogens or unacceptable levels of toxins or suspended solids. Drinking such water or using it in food preparation leads to widespread, acute and chronic illnesses and is a major cause of death and misery in many countries. The UN estimates that over 2.0 billion people have limited access to safe water and nearly 800 million people lack even the most basic supply of clean water. The main issue is the affordability of water purifying systems. Many people rely on boiling water or bottled water, which can be expensive. Therefore, technologies that are cost effective, sustainable, ease of operation/maintenance and the treatment processes with locally available materials are required. In this article, some unique low-cost sustainable technologies available/or in-use, i.e. natural filtration, riverbank filtration, biosand filtration, membrane filtration, solar water disinfection technique, biologically degradable materials such as moringa powder, scallop powder treatment, and biosand pitcher treatments have been discussed.

The Spatial Distribution of Nitrite Concentrations in a Large Drinking Water Distribution System in Finland

Nitrite in drinking water is a potential health hazard and monitoring its concentrations in distributed water is of paramount importance. When monochloramine is used in secondary disinfection in drinking water distribution systems (DWDSs), nitrite is often formed by nitrification in the biofilm on the inner surface of distribution pipes. This article attempts to identify areas with a risk of increased nitrite concentrations as well as the main reasons leading to nitrite occurrence in a large urban DWDS in Finland using spatial inspection of obligatory monitoring data. Nitrification was found to occur throughout the study area, though nitrite was not increased everywhere. Instead, nitrite was increased close to the water treatment plants (WTPs) and was connected to fresh drinking water than stagnant drinking water. Temperature effects on nitrite concentrations were surprisingly insignificant, even though it is well known that nitrification reactions are affected by temperature. The temperature dependence of ammonium and total residual chlorine was more significant than the dependence of nitrite. The findings of this study emphasize the need to monitor nitrite concentrations close to WTPs.

Health Risk Assessment of Employees Exposed to Chlorination By-products of Recreational Water in Large Amusement Parks in Shanghai

Objective Chlorination is often used to disinfect recreational water in large amusement parks;however,the health hazards of chlorination disinfection by-products(DBPs)to occupational populations are unknown.This study aimed to assess the exposure status of chlorinated DBPs in recreational water and the health risks to employees of large amusement parks.Methods Exposure parameters of employees of three large amusement parks in Shanghai were investigated using a questionnaire.Seven typical chlorinated DBPs in recreational water and spray samples were quantified by gas chromatography,and the health risks to amusement park employees exposed to chlorinated DBPs were evaluated according to the WHO's risk assessment framework.Results Trichloroacetic acid,dibromochloromethane,bromodichloromethane,and dichloroacetic acid were detected predominantly in recreational water.The carcinogenic and non-carcinogenic risks of the five DBPs did not exceed the risk thresholds.In addition,the carcinogenic and non-carcinogenic risks of mixed exposure to DBPs were within the acceptable risk limits.Conclusion Typical DBPs were widely detected in recreational water collected from three large amusement parks in Shanghai;however,the health risks of DBPs and their mixtures were within acceptable limits.

Progress in Analytical Methods of Halogenated Disinfection By-Products

Ensuring the health and safety of drinking water is crucial for both nations and their citizens.Since the 20th century,the disinfection of drinking water,effectively controlling pathogens in water sources,has become one of the significant advances in public health.However,the disinfectants used in the process,such as chlorine and chlorine dioxide,react with natural organic matter in the water to produce disinfection by-products(DBPs).Most of these DBPs contain chlorine,and if the source water contains bromine or iodine,brominated or iodinated DBPs,collectively referred to as Halogenated disinfection byproducts(X-DBPs),are formed.Numerous studies have found that X-DBPs pose potential risks to human health and the environment,leading to widespread concern.Mass spectrometry has become an important means of discovering new types of X-DBPs.This paper focuses on the study of methods for analyzing X-DBPs in drinking water using mass spectrometry.

Preozonation of bromide-bearing source water in south China

The effectiveness of preozonation was evaluated on treating a bromide-bearing dam source water in south China through batch-scale experiments. Preozonation at ozone doses of 0.5-1.0 mg/L （at ozone consumption base） enhanced total organic carbon （TOC） removal through coagulation, and resulted in an almost linear reduction of ultraviolet absorbance at 254 nm （LW2s4）. The removals of TOC （after coagulation） and UV254 at the ozone dose of 1.0 mg/L were 36% and 70%, respectively. Preozonation at an ozone dose between 0.5 and 1.0 mg/L resulted in the removal of disinfection byproducts formation potential （DBFP） including trihalomethane formation potential （THMFP） and haloacetic acid formation potential （HAAFP） for about 50%. The removals of THMFP and HAAFP decreased with the further increase of ozone dose. Ozonation of bromide-bearing water （bromide concentration, 34 μg/L） produced a bromate concentration under the detection limit（2μg/L） at ozone doses 〈1.5 mg/L. However, bromate 〉10μg/L could be produced when the bromide concentration was increased to 96 μg/L.

Study of Wastewater Advanced Treatment and Reclaimed Water Reuse for a Large General Hospital

A combined process of biological aerated filter,fiber ball filter and chlorine dioxide disinfection was used to treat effluent of primary hospital wastewater in Jinan.Its treatment capacity was designed as 400m^3/d based on the reclaimed water demand of the large general hospital.The quality of the effluent can meet the requirements of the Reuse of Urban Recycling Water——Water Quality Standard for Urban Miscellaneous Water Consumption(GB/T18920-2002).The project has less site area,low investment and operation cost and high automatic control level,so it can provide scientific references for design and operation of similar projects.

Degradation of Polymer &Elastomer Exposed to Chlorinated Water—A Review

In water industry, the chlorine is mostly used as a disinfectant agent. The chlorine present in potable water as a disinfectant has been reported to reduce the lifetime of contact polymeric material. This occurs in polymer pipes and it is now very common in plumbing and other parts of the drinking water distribution system. For more than 50 years, Polymer & Elastomeric materials have been used ubiquitously in drinking water distribution systems. Polymer & Elastomeric materials have successfully been used in a variety of applications ranging from rubber gaskets, to valves, to hydrants, to fittings. Polymer & Elastomers that degrade more quickly than expected create service problems, make it difficult for utilities to cost efficient plan preventive maintenance programs, and negatively affect customer relations. This review paper gives an insight idea to a reader about the selection of proper polymer & elastomer and predicting its performance in chlorinated water. Also the mechanism of degradation of Polymer & elastomer in chlorine environment and some model of life expectancy of in-service of Polymer & elastomer in various conditions and parameter in chlorinated water were discussed.

Utilisation of Water Purification “Tablets” at Household Level in Namibia and Tanzania

Generally disinfection of water at household level can be achieved using several soluble tablets or chemicals which have been proven to render water to be microbiologically safe. The use of disinfectants at household levels has been reported to contribute to the reduction of waterborne diseases in areas with limited supply of piped water. Water guard is produced and widely used in Tanzania especially in the rural and informal settlements;whilst in Namibia, water marker and Aqua tabs are imported and distributed to similar communities. Sodium Hypochlorite, a chlorine base chemical which is either in powder or tablet form is widely used in the two countries. Through informed consent community volunteers were used for the collection of water from shallow wells, which was subsequently treated and analysed in Tanzania. Volunteers were also asked about their methods of water treatment and storage. In Namibia, information on appropriate use of purification chemicals at household level was obtained through desktop review and key informants. The aim of this study was to investigate the effectiveness and proper utilisation of the water purification chemicals at household level in the two countries. The appropriate use of chemical doses provides 100% disinfection efficiency with chlorine residue of less than 0.3 mg/l which is within the recommended limits for WHO. The authors conclude that household water purification chemicals are effective against pathogens;however the chemicals’ effectiveness depends on appropriate use in terms of mixing, handling and hygiene of container used. A common problem experienced by Namibia and Tanzania is related to improper mixing, which affects the taste of water, and thus influences the user’s choice of prolonged use.

2018—2022年辽宁省农村集中式供水单位消毒状况及效果分析

目的 了解辽宁省农村地区集中式供水消毒状况,并进一步了解不同方式消毒情况及效果,分析其影响因素,为保障农村饮用水卫生安全提供参考。方法 2018—2022年,在辽宁省14个市所有乡镇辖区范围内,每个乡镇设置2~4个监测点,收集集中式供水单位基本信息,每个水厂采集1份出厂水和1~2份末梢水,枯水期和丰水期各采集1次。按照《生活饮用水标准检验方法》(GB/T 5750-2006)进行微生物指标(总大肠菌群、大肠埃希氏菌和菌落总数)检验。采取消毒措施的水样检测消毒剂指标(游离氯或二氧化氯)。检测结果按照《生活饮用水卫生标准》(GB 5749-2006)进行评价,对微生物和消毒剂指标结果进行分析。结果 共调查供水单位5 384个,水源类型主要为地下水(94.42%);供水规模主要为小型集中式供水(96.34%)。消毒的供水单位739个(13.72%),其中消毒方式包括氯化消毒(69.68%)、二氧化氯消毒(27.60%)和紫外线消毒(2.72%);消毒设备按要求使用的占比60.35%。氯化消毒以漂白粉为主(81.55%),二氧化氯消毒以高纯二氧化氯为主(67.16%)。共采集检测水样23 427份,其中消毒水样3 389份(紫外线消毒水样84份,氯化和二氧化氯消毒水样3 305份)。游离氯和二氧化氯指标达标率为91.20%。二氧化氯消毒水样达标率(96.31%)高于氯化消毒水样(89.22%),达标率差异有统计学意义(χ^(2)=41.70,P<0.05)。丰水期游离余氯达标率高于枯水期;末梢水游离余氯的达标率高于出厂水;消毒设备按要求使用的水样游离余氯达标率高于偶尔使用和人工投加的情况,差异均有统计学意义(P<0.05)。不同水期、水样类型、水源、消毒剂投加方式,二氧化氯达标率的差异均无统计学意义(P>0.05)。消毒水样总大肠菌群、大肠埃希氏菌和菌落总数达标率高于不消毒水样,差异有统计学意义(P<0.05)。氯化消毒水样总大肠菌群和菌落总数达标率均高于二氧化氯消毒水样,且差异有统计学意义(P<0.05)。结论 辽宁省农村饮用水消毒状况有待加强,氯化消毒消毒效果优于二氧化氯消毒。今后应加强农村饮用水消毒的监管监测,保障饮用水安全。

2020—2022年苏州市生活饮用水中消毒副产物监测结果分析

为了解江苏省苏州市生活饮用水中消毒副产物(Disinfection By-Products,DBPs)的污染情况,为饮用水安全管理提供依据,按照《生活饮用水标准检验方法》(GB/T 5750—2023),2020—2022年共采集苏州市生活饮用水样852份,其中出厂水276份、末梢水396份、二次供水180份,对水样中12种DBPs进行检测,依据《生活饮用水卫生标准》(GB/T 5749—2022)进行评价。结果表明,除1,2-二氯乙烷、四氯化碳外,苏州市生活饮用水中其他DBPs均有检出,但均在限值标准内,水样的总体合格率为100%;不同类型水样DBPs浓度和检出率差异不显著(P>0.05)。这表明苏州市生活饮用水总体情况较好,但相关部门应仍需加强DBPs监测,做好其健康风险评估工作,为生活饮用水健康风险管理提供科学支撑。

高藻水处理过程中的加氯方式优化及藻源嗅味物质控制

针对高藻期水库水,研究了不同预氯化-消毒组合方式对常规工艺处理高藻水过程中污染物去除及藻源嗅味物质转化和去除的影响,以及预氯化-消毒组合方式对粉末活性炭吸附控制藻源嗅味物质效果的影响。结果表明,高藻水预氯化会使水中以非溶解态存在的2-甲基异莰醇(2-MIB)、土臭素(GSM)等藻源嗅味物质快速转化为溶解态。常规工艺能有效去除高藻水中的非溶解态嗅味物质,但对溶解态嗅味物质的去除效果十分有限;预氯化对常规工艺去除高藻水中2-MIB和GSM存在较大不利影响。粉末活性炭吸附能有效提升对2-MIB和GSM的去除效果,但预氯化会显著降低粉末活性炭吸附+常规工艺对2-MIB和GSM的总体去除效果。因此,对存在藻源嗅味物质的高藻水,不建议进行预氯化处理。