Drinking water quality & health risk assessment of secondary water supply systems in residential neighborhoods

Secondary water supply systems(SWSSs)are important components of the water supply infrastructure that ensure residents’drinking water safety.SWSSs are characterized by long detention time,warm temperature,and unreasonable management,which may trigger the deterioration of water quality and increase risks.In this study,drinking water quality index(DWQI)and health risk assessment(HRA)were selected and modified to quantitatively assess the water quality and health risks of SWSSs in residential neighborhoods.In total,121 seasonal water samples were selected.It was observed that the water quality was excellent with the DWQI of 0.14±0.04,excluding one sample,which was extremely poor owing to its excessive total bacterial count.The HRA results revealed that the health risks were low:negligible non-carcinogenic risk for any population;negligible and acceptable carcinogenic risk for children aged 6–17 and adults.However,samples revealed higher carcinogenic risk(7.63×10−5±3.29×10−6)for children aged 0–5,and arsenic was the major substance.Summer samples had poor water quality and higher health risks,which called for attention.To further investigate the water quality and health risks of SWSSs,monthly sampling was conducted during summer.All 24 water samples were qualified in Chinese standard(GB 5749-2022)and characterized as excellent quality.Their HRA results were consistent with the seasonal samples’and the health risks were mainly concentrated in May.Overall,our study provides a suitable framework for water quality security,advice for managers,and references for administrators in other cities.

Development and application of innovative technologies for drinking water quality assurance in China

The continuously deteriorating quality of source water is threatening the safety of drinking water in China.Various efforts have been made to update water treatment processes to decrease the pollution problems of drinking water,such as protection of drinking water sources,enhance-ment of conventional treatment processes,and development of new or advanced treatment technologies.This paper reviews a variety of protection and remediation methods for drinking water sources,development and application of drinking water treatment technologies,new technologies for special pollutants removal from groundwater,and the latest research progress on water distribution systems in China.

Quality Problems in Waters Used for Drinking Purposes in Italy

With a grant from the Italian Ministry of the Environment, the National Institute of Health (Istituto Superiore di Sanita) promoted and coordinated some activities aimed at determining the extent and the intensity of contamination of waters used for human consumption by some chemical agents, and describing causes and modalities of contamination and human health implications. The chemical agents examined were herbicides, nitrates, trihalomethanes, asbestos, manganese and fluoride. In this paper a first nationwide picture of these problems is reported.

Arsenic Distribution Pattern in Different Sources of Drinking Water and their Geological Background in Guanzhong Basin, Shaanxi, China

To study arsenic （As） content and distribution patterns as well as the genesis of different kinds of water,especially the different sources of drinking water in Guanzhong Basin,Shaanxi province,China,139 water samples were collected at 62 sampling points from wells of different depths,from hot springs,and rivers.The As content of these samples was measured by the intermittent flowhydride generation atomic fluorescence spectrometry method （HG-AFS）.The As concentrations in the drinking water in Guanzhong Basin vary greatly （0.00-68.08 tg/L）,and the As concentration of groundwater in southern Guanzhong Basin is different from that in the northern Guanzhong Basin.Even within the same location in southern Guanzhong Basin,the As concentrations at different depths vary greatly.As concentration of groundwater from the shallow wells （〈50 m deep,0.56-3.87 μg/L） is much lower than from deep wells （110-360 m deep,19.34-62.91 μg/L）,whereas As concentration in water of any depth in northern Guanzhong Basin is 〈10 μg/L.Southern Guanzhong Basin is a newly discovered high-As groundwater area in China.The high-As groundwater is mainly distributed in areas between the Qinling Mountains and Weihe River; it has only been found at depths ranging from 110 to 360 m in confined aquifers,which store water in the Lishi and Wucheng Loess （Lower and Middle Pleistocene） in the southern Guanzhong Basin.As concentration of hot spring water is 6.47-11.94 μg/L; that of geothermal water between 1000 and 1500 m deep is 43.68-68.08 μg/L.The high-As well water at depths from 110 to 360 m in southern Guanzhong Basin has a very low fluorine （F） value,which is generally 〈0.10 mg/L.Otherwise,the hot springs of Lintong and Tangyu and the geothermal water in southern Guanzhong Basin have very high F values （8.07-14.96 mg/L）.The results indicate that high As groundwater in depths from 110 to 360 m is unlikely to have a direct relationship with the geothermal water in the same area.As concentration of all reservoirs and rivers （both contaminated and uncontaminated） in the Guanzhong Basin is 〈10 μg/L.This shows that pollution in the surface water is not the source of the high-As in the southern Guanzhong Basin.The partition boundaries of the high-and low-As groundwater area corresponds to the partition boundaries of the tectonic units in the Guanzhong Basin.This probably indicates that the high-As groundwater areas can be correlated to their geological underpinning and structural framework.In southern Guanzhong Basin,the main sources of drinking water for villages and small towns today are wells between 110-360 m deep.All of their As contents exceed the limit of the Chinese National Standard and the International Standard （〉10 μg/L） and so local residents should use other sources of clean water that are 〈50 m deep,instead of deep groundwater （110 to 360 m） for their drinking water supply.

Comparative analysis of bacterial contamination in tap and groundwater: A case study on water quality of Quetta City, an arid zone in Pakistan

Water is an essential element on earth,which provides human a variety of services in domestic use,agriculture,or industries.However,some serious health risks of drinking water are associated with microbial contamination,particularly with fecal matter.Therefore,microbial quality assessment is considered to be a necessary component of water quality assessment.This study investigates microbial contamination of water distributary system around the city by comparing groundwater(GW)and tap water(TW)quality in Quetta city.31 GW samples and 31 TW samples were collected in the study area during the months of September,October,and November.Fecal coliform test was carried out in laboratory and their average total coliform contamination was computed.Results showed that the TW sample were all contaminated by coliform except for Chiltan town,hence are not considered suitable for drinking without any treatment according to WHO drinking water quality standards.The average coliform concentrations were 12 in Quetta main city,11.6 in Jinnah town,5.3 in Satallite town,10 in Shahbaz town and 5 in Brewery town(0/100 mL CFU)and the TW samples from the three towns were even more contaminated with E.coli.Whereas among the GW,average microbial concentrations were 1.8 in Quetta main city,2 in Satallite town,1.4 in Shahbaz town,and 0.4 in Chiltan town(0/100 mL CFU),respectively,which shows that the contamination is occurring within the water distributary pipeline system when the water flows through the pipelines.Moreover,this research will be valuable for researchers and administrative authorities to conduct elaborative studies,and develop new policies to prevent further deterioration of drinking water in the water distribution system by pathogenic microorganisms and ensure safe drinking water to the public of Quetta city.

An Assessment of Ingestion Dose due to the Intake of ^210Po and ^210Pb through Drinking Water of Eloor, Ernakulam District, Kerala, India

The present study aims at measuring the activity concentrations of ^210Po and ^210Pb in the potable water of Eloor, a major industrial belt in the Ernakulam district of Kerala, India with an aim of evaluating resultant ingestion dose to critical population. The industrial units located in Eloor discharge their treated effluents into the river Periyar and the surrounding environs. The two major industries of interest with respect to NORMs are the fertilizer plant, processing rock phosphate and the monazite processing plant, which had been in operation for the last 50 years. For sampling, Eloor region was divided into four zones and a total of 55 water samples from different locations were collected and analysed as per standard analytical procedure manual of BARC. The ^210Po concentration ranged between 0.3 to 4.7 mBq.L^-1 and ^210Pb ranged from 0.6 to 4.3 mBq.L^-1. All values are well below the limit of 0.1 Bq.Ll recommended by World Health Organization. Statistical analysis shows a good co-relation between ^210Po and ^210Pb in the water samples analyzed and the mean activity concentration is found to be relatively high in the western region of Eloor compared to other regions. The annual effective dose equivalent to man from ^210Po and ^210Pb through drinking water intake were estimated and found to be 1.13 μSv.y^-1 and 0.99 μSv.y^-1 respectively, which is well below the reference level of committed effective dose （100 μSv.y^-1） recommended by WHO.

Spatial and Temporal Analyses of Water Quality in the Dhrabi Watershed of Pakistan： Issues and Options

Monitoring water quality is important for maintaining a healthy watershed, but it is mostly ignored in watershed planning and management. In the Dhrabi watershed of Pakistan, the quality of surface water was monitored at 16 locations to assess suitability for irrigation over regular intervals during the period 2007-2010. Similarly, groundwater quality was monitored at 10 locations for drinking and irrigation purposes. There was high spatial and temporal variability in surface water quality. Electrical conductivity （EC） and residual sodium carbonate （RSC） either exceeded or fluctuated around permissible limits at most of the locations throughout the monitoring period. Therefore, the use of such water for irrigation needs special care, otherwise its prolonged use may pose soil salinity and sodicity problems. The trend of EC and RSC for groundwater was similar to that for surface water. Exchangeable Mg2＋ exceeded permissible limits for most of the surface water and groundwater samples. In addition, microbial analysis of groundwater revealed that only two out of eight monitoring points during August 2009, none out of eight points during February 2010, and one out of nine points during June 2010 provided water fit for drinking. Soil samples were collected from the catchment areas of the major contributing streams and from the beds of the Kallar Kahar Lake and the Dhrabi Reservoir. The soil samples from the catchments showed high salinity and sodicity that may be the cause of high salinity and sodicity in the streams. The highest EC, sodium adsorption ratio （SAP,） and exchangeable sodium percentage （ESP） in the bed samples from the Kallar Kahar Lake were about 43 dS/m, 56, and 45, respectively. These high values were due to the saline water brought into the lake with the runoff.

Cascade Tank Water Quality Management: A Case Study in Thirappane Tank Cascade System, Sri Lanka

Tank cascade system(TCS)is a series of tanks located in a meso-catchment and has been accepted as a Globally Important Agricultural Heritage System found in Sri Lanka.Ecosystem components of the TCS play a major role in purifying water within the system.This study attempted to investigate the water quality status and the farmers’willingness to rehabilitate the ecosystem components of the Thirappane TCS.Drinking and irrigation water quality parameters were tested in 34 locations and drinking and irrigation water quality indexes were calculated.Participatory rural appraisal and a questioner survey were conducted to gather social data.Water of TCS was observed to be appropriate for irrigation but not for drinking during the Maha cropping season.Based on the results of the Nitrate(as NO_(3)^(-))and Total Phosphate(as PO_(4)^(3-)),water of TCS can be categorized as eutrophic.Presence of ecosystem features of tank cascade system,annual income of the respondents,satisfaction on the quality of water for drinking,and the awareness about the tank cascade system significantly influenced the participatory decisions of the community on the rehabilitation of TCS.This study shall be an example and an eye opener to formulate sustainable tank cascade management plan.

Perception of the Residential Environmental Quality of Yenagoa Metropolis,Nigeria

Residential environmental quality(REQ)affects human health and quality of life(QoL).Therefore,this study as­sessed residents’perception of the REQ of the Yenagoa metropolis.Data for the study were sourced from the 400 ad­ministered questionnaires,which required respondents to rate their REQ based on seven selected indicators(air quality,drinking water quality,housing location,sanitation,waste management,housing accessibility and noise pollution).The respondents were sampled using the multistage sampling technique.The data were analyzed using frequency,percent­age,t-test,ANOVA and REQ model.The findings show that the overall calculated REQ of Yenagoa was classified as“good quality”.The best-rated indicator was drinking water quality,while the least-rated was noise pollution.Ratings based on respondents’sex,income and educational status recorded similar results.Also,the respondents’perception of the REQ across the four zones was similar as the calculated ratings of all the zones fell under the“good quality”classification.Furthermore,the hypotheses tested revealed that there were no significant differences in the perception of the REQ by sex and income status,while significant variation exists by education status.Despite the general“good quality”rating,there is still room for improvement,especially in the areas of noise pollution,sanitation and housing location,which received relatively low ratings.

Occurrence of odor problems in drinking water of major cities across China

A comprehensive investigation into the occur-rence of odor problem at 111 drinking water treatment plants （DWTPs） in major cities across China was undertaken using both flavor profile analysis （FPA） and gas chromatography-mass spectrometry （GC-MS）. Eighty percent of source water samples exhibited odor problems, characterized by earthy/musty （41%） and swampy/septic （36%） odors, while the occurrence rate was lower （45%） in the finished water. Source water from rivers exhibited more pollution-origin odors, such as the swampy/septic odor, while that from lakes and reservoirs exhibited more algae- origin odors, such as earthy/musty odors. The occurrence rate of 2-methylisoborneol （2-MIB） in the surface source water samples was 75%, with 7% of samples containing 2- MIB concentrations of over 10 ng.L-1. The earthy/musty odor in the lake/reservoir water samples was mainly caused by 2-MIB （linear regression coefficient, R2= 0.69）, while the correlation between 2-MIB concentration and the earthy/musty odor intensity samples was weak （R2= 0.35） in the river-source water These results will be useful for the management of odor-quality problems in drinking water of China.

Organic chloramines in chlorine-based disinfected water systems： A critical review

This paper is a critical review of current knowledge of organic chloramines in water systems,including their formation, stability, toxicity, analytical methods for detection, and their impact on drinking water treatment and quality. The term organic chloramines may refer to any halogenated organic compounds measured as part of combined chlorine（the difference between the measured free and total chlorine concentrations）, and may include N-chloramines,N-chloramino acids, N-chloraldimines and N-chloramides. Organic chloramines can form when dissolved organic nitrogen or dissolved organic carbon react with either free chlorine or inorganic chloramines. They are potentially harmful to humans and may exist as an intermediate for other disinfection by-products. However, little information is available on the formation or occurrence of organic chloramines in water due to a number of challenges. One of the biggest challenges for the identification and quantification of organic chloramines in water systems is the lack of appropriate analytical methods. In addition, many of the organic chloramines that form during disinfection are unstable, which results in difficulties in sampling and detection. To date research has focussed on the study of organic monochloramines.However, given that breakpoint chlorination is commonly undertaken in water treatment systems, the formation of organic dichloramines should also be considered. Organic chloramines can be formed from many different precursors and pathways. Therefore, studying the occurrence of their precursors in water systems would enable better prediction and management of their formation.

Defluoridation of groundwater by calcined Mg/Al layered double hydroxide

The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation method and characterized by XRD,FT-IR and TGA-TDA analyses.Batch defluoridation experiments were performed under various conditions such as calcination,solution pH,contact time,temperature,material dosage and reuse.Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600℃.The maximum fluoride removal was obtained at solution pH of 6.85.Kinetics of fluoride removal followed the pseudo-second order kinetic model.The rise in solution temperature strongly enhances the removal efficiency.The adsorption mechanism involved surface adsorption,ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region.The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L,respectively,for Bejaad and Settat goundwaters.A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.