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.

Gross Alpha and Beta Activities and Related Lifetime Risks Assessment Due to Ingestion of Drinking Water from Different Sources in the District of Abidjan, Cote d’Ivoire

Drinking good quality water is essential for better health. It is therefore essential to assess the radiological quality of all water consumed in the District of Abidjan in order to prevent related hazards. Thus, the objective of this study was to assess the risk of cancer due to the ingestion of alpha and beta emitting radionuclides in the different types of water consumed in the region. A total of 63 water samples with 43 tap water samples, 5 bottled mineral water and 15 sachet water samples was collected and taken to GAEC laboratory for analysis. The low background Gas-less Automatic Alpha/Beta counting system (Canberra iMaticTM) was used to determine alpha and beta activity concentrations. Activity concentrations of both gross alpha and gross beta obtained in water sample were respectively lower than the WHO recommended limits of 0.1 Bq/l and 1 Bq/l. Also, the annual effective dose and total equivalent effective dose found in mineral bottled water samples were higher than in other types of water. The assessment of radiological lifetime risk has shown values of cancer risk due to ingestion alpha and beta emitters lower than recommended limit. These results indicate that there is no health hazard associated to consumption of water in the District of Abidjan.

Economic significance and environmental impacts of the Song Dam Drinking Water Project(SDDWP)in Garhwal Himalaya

With the population growth through natural growth and migration,coupled with the city expansion,it is the fact that Dehradun City in India faces severe water scarcity.Therefore,the Song Dam Drinking Water Project(SDDWP)is proposed to provide ample drinking water to Dehradun City and its suburban areas.This paper examined economic significance and environmental impacts of the SDDWP in Garhwal Himalaya,India.To conduct this study,we collected data from both primary and secondary sources.There are 12 villages and 3 forest divisions in the surrounding areas of the proposed dam project,of which 3 villages will be fully submerged and 50 households will be affected.For this study,50 heads of the households were interviewed in the 3 submerged villages.The questions mainly focused on economic significance,environmental impacts,and rehabilitation issues of the dam project.The findings of this study indicate that economic significance of the dam project is substantial,including providing ample water for drinking and irrigation,contributing to groundwater recharge,creating job opportunities,and promoting the development of tourism and fisheries in the Doon Valley.In terms of the rehabilitation of the affected people,there are only 50 households in need of rehabilitation.Currently,the arable land of these affected people is not sufficient to sustain their livelihoods.The entire landscape is fragile,rugged,and precipitous;therefore,the affected people are willing to rehabilitate to more suitable areas in the Doon Valley.Moreover,it is essential to provide them with sufficient compensation packages including the compensation of arable land,houses,cash,common property resources,institutions,belongingness,and cultural adaptation.On the other hand,the proposed dam project will have adverse environmental impacts including arable land degradation,forest degradation,loss of fauna and flora,soil erosion,landslides,and soil siltation.These impacts will lead to the ecological imbalances in both upstream and downstream areas.This study suggests that the affected people should be given sufficient compensation packages in all respects.Afforestation programs can be launched in the degraded areas to compensate for the loss of forest in the affected areas.

Drinking water and liver cancer *

AIM To study the relationship between mutagenicity of drinking water and incidence of liver cancer in high liver cancer incidence areas in Guangxi.

Gastric cancer risk in relation to tobacco use and alcohol drinking in Kerala, India-Karunagappally cohort study

AIM: To assess the risk of gastric cancer(GC) in relation to tobacco use and alcohol drinking in the Karunagappally cohort in Kerala, South India.METHODS: This study examined the association of tobacco use and alcohol drinking with GC incidence among 65553 men aged 30-84 in the Karunagappally cohort. During the period from 1990-2009, 116 GC cases in the cohort were identified as incident cancers. These cases were identified from the populationbased cancer registry. Information regarding risk factors such as socioeconomic factors and tobacco and alcohol habits of cohort members were collected from the database of the baseline survey conducted during 1990-1997. The relative risks(RRs) and the corresponding 95% confidence intervals(95%CIs) fortobacco use were obtained from Poisson regression analysis of grouped survival data, considering age, follow-up period, occupation and education.RESULTS: Bidi smoking was associated with GC risk(P = 0.042). The RR comparing current versus never smokers was 1.6(95%CI: 1.0-2.5). GC risk was associated with the number of bidis smoked daily(P = 0.012) and with the duration of bidi smoking(P = 0.036). Those who started bidi smoking at younger ages were at an elevated GC risk; the RRs for those starting bidi smoking under the age of 18 and ages 18-22 were 2.0(95%CI: 1.0-3.9) and 1.8(95%CI: 1.1-2.9), respectively, when their risks were compared with lifetime non-smokers of bidis. Bidi smoking increased the risk of GC among never cigarette smokers more evidently(RR = 2.2; 95%CI: 1.3-4.0). GC risk increased with the cumulative amount of bidi smoking, which was calculated as the number of bidis smoked per day x years of smoking(bidi-year; P = 0.017). Cigarette smoking, tobacco chewing or alcohol drinking was not significantly associated with GC risk. CONCLUSION: Among a male cohort in South India, gastric cancer risk increased with the number and duration of bidi smoking.

Drinking water production by uitrafiltration of Songhuajiang River with PAC adsorption

In recent years, membrane ultrafiltration （UF） of surface water for drinking water treatment has become a more attractive technology worldwide as a possible alternative treatment to conventional clarification. To evaluate the performance of ultrafiltration membranes for treatment of surface water in North China, a 48-m^2 low pressure hollow fiber membrane ultrafiltration pilot plant was constructed. Ultrafiltration was operated in cross-flow and with powdered activated carbon （PAC） adsorption. Turbidity was almost completely removed to less than 0.2 NTU （below Chinese standard 1 NTU）. It was found that PAC addition enhanced organic matter removal. The combined process of PAC/UF allowed to 41% removal of CODMn, 46% removal of DOC and 57% decrease in UV254 absorbance. The elimination of particles, from average 12000/ml in the raw water to approximately 15/ml in the permeated, was observed. When PAC concentration was below 30 mg/L, backwashing could recovery the membrane flux with backwash interval/backwashing duration of 1/30.

Relationship Between Microcystin in Drinking Water and Colorectal Cancer

Objective To investigate the association of microcystin (MC) in drinking water with the incidence of colorectal cancer. Methods The study was designed as a retrospective cohort. Eight townships or towns were randomly selected as the study sites in Haining City of Zhejiang Province, China. 408 cases of colon and rectum carcinomas diagnosed from 1977 to 1996 in the study sites were included, and a survey on types of drinking water of these patients was conducted. Samples of different water sources (well, tap, river and pond) were collected separately and microcystin concentrations were determined by indirect competitive ELISA method. Results The incidence rate of colorectal cancer was significantly higher in population who drank river and pond water than those who drank well and tap water. Compared to well water, the relative risk (RR) for colorectal cancer was 1.88 (tap), 7.94 (river) and 7.70 (pond) respectively. The positive rate (>50 pg/mL) of microcystin in samples of well, tap, river and pond water was 0, 0, 36.23% and 17.14% respectively. The concentration of microcystin in river and pond water was significantly higher than that in well and tap water (P<0.01). Spearman rank correlation analysis showed that in the study sites, the microcystin concentration of river and pond water was positively associated with the incidence of colorectal cancer (rs= 0.881, P<0.01). Conclusions The types of drinking water are positively associated with the incidence of colorectal cancer in the study sites, and this may be related to microcystin contamination of drinking water. Further biological study is needed to support the possible causative role of mycrocystin in carcinogenesis of colon and rectum.

Soft drinks consumption and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is a common clinical condition which is associated with metabolic syndrome in 70% of cases.Inappropriate dietary fat intake,excessive intake of soft drinks,insulin resistance and increased oxidative stress combine to increase free fatty acid delivery to the liver,and increased hepatic triglyceride accumulation contributes to fatty liver.Regular soft drinks have high fructose corn syrup which contains basic sugar building blocks,fructose 55% and glucose 45%.Soft drinks are the leading source of added sugar worldwide,and have been linked to obesity,diabetes,and metabolic syndrome.The consumption of soft drinks can increase the prevalence of NAFLD independently of metabolic syndrome.During regular soft drinks consumption,fat accumulates in the liver by the primary effect of fructose which increases lipogenesis,and in the case of diet soft drinks,by the additional contribution of aspartame sweetener and caramel colorant which are rich in advanced glycation end products that potentially increase insulin resistance and inflammation.This review emphasizes some hard facts about soft drinks,reviews fructose metabolism,and explains how fructose contributes to the development of obesity,diabetes,metabolic syndrome,and NAFLD.

Particle properties in granular activated carbon filter during drinking water treatment

The elemental composition and bacteria attached in particles were investigated during granular activated carbon （GAC） filtration.The experimental results showed that trapped influent particles could form new,larger particles on GAC surface.The sloughing of individuals off GAC surface caused an increase in effluent particles in the size range from 5 to 25 μm.The selectivity for element removal in GAC filters caused an increasing proportion of metallic elements in the effluent particles.The distribution of molar ratio indicated a complicated composition for large particles,involving organic and inorganic substances.The organic proportion accounted for 40% of total carbon attached to the particles.Compared with dissolved carbon,there was potential for the formation of trihalomethanes by organic carbon attached to particles,especially for those with size larger than 10 μm.The pure carbon energy spectrum was found only in the GAC effluent and the size distribution of carbon fines was mainly above 10 μm.The larger carbon fines provided more space for bacterial colonization and stronger protection for attached bacteria against disinfection.The residual attached bacteria after chorine disinfection was increased to 10 2-10 3 CFU/mL within 24 hours at 25°C.

Legislation on protection of drinking water sources and local management practices in the Pearl River Delta region of China

The protection of drinking water sources is vital to urban development and public health.In this study,the current situation of the mandatory protection area for drinking water source in the Pearl River Delta region was investigated using a method combining Google Earth with the field survey.The gaps between management practices and legislation requirements were analyzed.Finally,several countermeasures for water resource protection were proposed as follows:to promote delineation in a more scientific way,to safeguard the sanctity of the law,to make better plan on water saving,and to encourage public participation in supervision and management.

Alcohol Drinking, Dyslipidemia, and Diabetes： A Population-based Prospective Cohort Study among Inner Mongolians in China

Objective No previous studies have evaluated the association between dyslipidemia, alcohol drinking, and diabetes in an Inner Mongolian population. We aimed to evaluate the co-effects of drinking and dyslipidemia on diabetes incidence in this population. Methods The present study was based on 1880 participants from a population-based prospective cohort study among Inner Mongolians living in China. Participants were classified into four subgroups according to their drinking status and dyslipidemia. Multivariate logistic regression analysis and receiver operating characteristic （ROC） curves were used to evaluate the association between alcohol drinking, dyslipidemia, and diabetes. Results During the follow-up period, 203 participants were found to have developed diabetes. The multiva riable-adjusted odds ratios （95% confidence interval） for the incidence of non-dyslipidemia/drinkers, dyslipidemia/non-drinkers, and dyslipidemia/drinkers in diabetic patients were 1.40 （0.82-2.37）, 1.73 （1.17-2.55）, and 2.31 （1.38-3.87）, respectively, when compared with non-dyslipidemia/non-drinkers. The area under the ROC curve for a model containing dyslipidemia and drinking status along with conventional factors （AUC=0.746） was significantly （P=O.003） larger than the one containing only conventional factors （AUC=0.711）. Conclusion The present study showed that dyslipidemia was an independent risk factor for diabetes, and that drinkers with dyslipidemia had the highest risk of diabetes in the Mongolian population. These findings suggest that dyslipidemia and drinkin8 status may be valuable in predicting diabetes incidence.

Effects of fulvic acid and humic acid on aluminum speciation in drinking water

This article focused on the influences of fulvic acid and humic acid on aluminum speciation in drinking water. Factors including the concentration of residual chlorine and pH value had been concerned. Aluminum species investigated in the experiments included inorganic mononuclear, organic mononuclear, mononuclear, polymer, soluble, and suspended forms. It was found that the effects of fulvic acid and humic acid on aluminum speciation depended mainly on their molecular weight. Fulvic acid with molecular weight less than 5000 Dalton had little influence on aluminum speciation; while fulvic acid with molecular weight larger than 5000 Dalton and humic acid would increase the concentration of soluble aluminum significantly even at concentration below 0.5 mg/L （calculated as TOC）. Aluminum species, in the present of fulvic acid with molecular weight larger than 5000 Dalton and humic acid, were more stable than that in the present of fluvic acid with molecular mass less than 5000 Dalton, and varied little with reaction time. Within pH range 6.5-7.5, soluble aluminum increased notably in water with organic matter. As the concentration of residual chlorine increased, the effects of fulvic acid and humic acid became weak. The reactions between humic acid, fulvic acid with large molecular weight, and aluminum were considered to be a multi-dentate coordination process. With the consideration of aluminum bioavailability, reducing the concentration of fulvic acid and humic acid and keeping the pH value among 6.5-7.5 were recommended during drinking water treatment.

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.

Genotoxicity evaluation and a primary risk assessment of organic pollutants in the drinking water sources of Nanjing, China

An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system （MEAS）. For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference （p〈0.01） was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity （AS） of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity （TAS） of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.

Factors effecting aluminum speciation in drinking waterby laboratory research

Effects of aluminum on water distribution system and human health mainly attribute to its speciation in drinking water. Laboratory experiments were performed to investigate factors that may influence aluminum speciation in water supply system. The concentration of soluble aluminum and its transformation among other aluminum species were mainly controlled by kinetics processes of related reactions. Total aluminum concentration had a notable effect on the concentrations of mononuclear and soluble aluminum in the first 4 day; then its effect became weak. At pH above 7.50, both fluoride and orthophosphate had little effect on aluminum speciation; while, when the solution pH was below 7.50, the concentrations of mononuclear and soluble aluminum were proportional to the concentration of fluoride and inversely proportional to the concentration of orthophosphate. Both mononuclear and polynuclear silicic acids could complex with mononuclear aluminum by forming soluble aluminosilicates. In addition, the adding sequence of orthophosphate and aluminum into drinking water would also affect the distribution of aluminum species in the first 4 day. In order to minimize aluminum bioavailability in drinking water, it was suggested that orthophosphate should be added prior to coagulant process, and that the concentrations of fluoride and silicic acids should be controlled below 2.0 and 25 mg/L, respectively, prior to the treatment. The solution pH in coagulation and filtration processes should be controlled in the range of 6.50-7.50.

Performance of microbiological control by a point-of-use filter system for drinking water purification

Purification capacity of a faucet mounted type water filter for home use was evaluated, particularly with regard to microbiological performance under different running conditions. Biofilms were formed inside the filter, affecting the bacterial quality of the effluent water. Low flow rate, long stagnation period and high filter temperature were found favorable for bacterial growth inside. By commercial analytical profile index （API） kits, ten different bacterial species were identified in drinking water, four of which were probably contributed to the biofilm formation since they were also present in the biofilm. Fluorescence in situ hybridization （FISH） was used to confirm the API identification results, and direct viable count （DVC） method was employed to improve the sensitivity of FISH for the isolated Acinetobacter spp. and Pseudomonas putida as models. Relationship between the filter operating condition and the bacterial community alteration was partly revealed, which could provide the basic knowledge for the filter design and its practical use.

Health Risk Assessment on Rural Drinking Water Safety —A Case Study in Rain City District of Ya’an City of Sichuan Province

Taking Rain City District of Ya’an for example, this paper based on ComGIS (Component Object Model Geographic Information System) platform takes comprehensive and systematic detection on the exposure dose of chemical carcinogens and non-carcinogens from drinking water sources in this region and discusses health risk assessment of single factor and the whole health risk assessment. As, Hg, Cr, Pb, Cd and fluorides in some drinking water sources of Rain City District are analyzed according to Standards For Drinking Wa-ter Quality (GB5749-2006). A health risk assessment model called USEPA is also applied to drinking water health risk assessment and management countermeasure is proposed. The results show that the greatest health risk for individual person per year is caused by Cr(VI). The health risk of carcinogens is much higher than that of non-carcinogens: the greatest risk value due to non-carcinogen pollutants is caused by fluoride (F), achieving 1.05×10-8/a. The ranking of risk values due to non-carcinogen pollutants by drinking water is Pb>fluoride (F)>Hg, within Pb accounting for 44.77%, fluo-ride (F) accounting for 34.30% and Hg accounting for 20.92%. The average individual carcinogenesis annual risk of Cr(VI) is the greatest, achieving 8.91×10-4/a. The ranking of risk value due to chemical carcinogen by rural drinking water of Ya’an is Cr6+>As>Cd, within Cr6+ accounting for 91.12%, As accounting for 5.89% and Cd accounting for 3.00%. Based on this, the strategy and measures of the health risk management are put forward. This study has worked efficiently in practice. Compared with the same kind of methods which have been found, the paper has the outstanding results for the health risk assessment of the rural drinking water safety.

Application of PCR-DGGE in Research of Bacterial Diversity in Drinking Water

Objective To analyze the structure of bacteria in drinking water by molecular biological techniques, Methods DNA of bacteria in drinking water was directly extracted without culture. 16S ribosomal DNA fragments, including V-6, -7, and -8 regions, were amplified with universal primers （EUBf933CJC and EUBr1387） and analyzed by DGGE. Results DGGE indicated that amplification products could be separated, The results showed that DGGE could be used in the separation of different microbial 16SrRNA genes extracted from drinkng water. Though there were special bacteria in different water samples, the predominant bacteria were essentially the same. Three sequences of the reclaimed specific bands were obtained, and phylogenetic tree of these bands was made. Conclusion Bacterial diversity in drinking water is identified by molecular biological techniques.

Pilot Study on Nanofiltration Combined with Ozonation and GAC for Advanced Drinking Water Treatment

A pilot-scale study of advanced drinking water treatment was carried out in test site, and a combination of ozonation, granular activated carbon (GAC) and nanofiltration was employed as the experimental process. By optimizing the operational parameters of ozonation and GAC, a large quantity of micro-pollutants in drinking water was removed, which made the post-positioned nanofiltration operate more reliably. It was evident that nanofiltration shows good performance for removing residual organic matter, meantime partial minerals can also be retained by nanofiltration. Therefore the quality of drinking water can be further improved. In addition, NF membrane fouling and scaling can be solved by concentrate recycling, anti-scalant dosing and chemical rinsing effectively. By GAC adsorption for the residue chlorine and ozone self-decomposition, their oxidation on NF membrane material can be eliminated completely.

Researches on Formation of Haloacetic Acids in Chlorination of Drinking Water by a Novel Technique

Haloacetic acids(HAAs) are formed during the chlorination of drinking water,which are harmful to people′s health due to their carcinogenic and mutagenic effects. In the present study,a detection method combining methyl tert -butyl ether(MtBE) extraction with acid catalysis and gas chromatography coupled with an electron capture detector(GC/ECD) was developed for determining HAAs. The detection limit of this method(MDL) and relative standard deviation(RSD) were below 0.37 μg/L and 6.2%,respectively. The laboratory chlorination experiments were conducted with the purpose of investigating the influences of reaction time,temperature,UV_ 254 ,bromide and ammonia-nitrogen on the formation of HAAs. The results show that the formation amount of HAAs increases with increasing reaction time and temperature,respectively;and there exists a linear relationship between the formation of HAAs and UV_ 254 . The formation amount of HAAs decreases first and then increases as the bromide ion concentration increases,and adding NH +_4 is a possible way to control the formation of HAAs.