Poor water quality exacerbates multidimensional poverty in developing nations. Often centralized treatment facilities generate acceptable water quality, but the water is contaminated during ...distribution. Methods to assess sources of contamination in water distribution systems are lacking. A case study of two methods, human risk assessment linked to water distribution system sampling was conducted in Hyderabad, Pakistan to determine areas requiring infrastructure rehabilitation. Water samples from source water (i.e., the Indus River), treatment plant effluent and from taps in the water distribution system were analyzed by atomic adsorption spectroscopy for metals and metalloids (As, Cd, Cr, Hg, and Pb) and water quality parameters (dissolved and suspended solids, pH, conductivity, and total organic carbon). Source water exceeded acceptable drinking water levels for As, Cd, total Cr, and Pb, while the treatment plant effluent concentrations were acceptable. Concentrations of all metals and metalloids, except Hg, increased in the water distribution system post-treatment, exceeding safe drinking limits in at least one location, suggesting contamination of the water during distribution. A deterministic and a probabilistic risk assessment were conducted to evaluate two scenarios: (1) unrestricted use of piped water for all household purposes, including as drinking water and (2) restricted use of the water for purposes other than drinking in the household, including only dermal and inhalation exposure pathways. The water was deemed unsafe for unrestricted use as the sole source of drinking water by both risk assessment methods. Yet when an alternative source of drinking water was assumed and the piped water was used only for bathing and dish washing, the probabilistic risk assessment revealed acceptable health risks to the population, while the overly conservative deterministic risk assessment suggested unacceptable risks. The combined methods of water sampling, risk assessment and correlation analysis suggested areas for rehabilitation of the water distribution system in Hyderabad, Pakistan and these methods can be adopted in other developing nations to target limited funds for infrastructure rehabilitation.
•Probabilistic risk assessment reveals water distribution system failure points.•Heavy metals in water a risk from exposure during showering and bathing.•Probabilistic risk assessment is preferred to deterministic methods for modeling.
Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were previously detected (≥4 ng/L) in 65% and 30%, respectively, of 23 New Jersey (NJ) public drinking water systems (PWS) ...sampled in 2006. We now report on a 2009 study of the occurrence of PFOA, PFOS, and eight other perfluorinated compounds (PFCs) in raw water samples from 30 intakes (18 groundwater and 12 surface water) from 29 additional NJ PWS. Between 1 and 8 PFCs were detected (≥5 ng/L) in 21 (70%) of 30 PWS samples at total PFC concentrations of 5–174 ng/L. Although PFOA was the most commonly detected PFC (57% of samples) and was found at the highest maximum concentration (100 ng/L), some of the higher levels of other PFCs were at sites with little or no PFOA. Perfluorononanoic acid was detected more frequently (30%) and at higher concentrations (up to 96 ng/L) than in raw or finished drinking water elsewhere, and it was found at several sites as the sole or predominant PFC, a pattern not reported in other drinking water studies. PFOS, perfluoropentanoic acid, and perfluorohexanoic acid were each detected in more than 20% of samples, while perfluoroheptanoic acid, perfluorobutane sulfonic acid, and perfluorohexane sulfonic acid were detected less frequently. Perfluorobutanoic acid was found only once (6 ng/L), and perfluorodecanoic acid was not detected. Total PFCs were highest in two reservoirs near an airfield; these were also the only sites with total perfluorosulfonic acids higher than total perfluorocarboxylic acids (PFCAs). PFC levels in raw and finished water from the same source were similar at those sites where both were tested. Five wells of two additional NJ PWS known to be contaminated with PFOA were also each sampled 4–9 times in 2010–13 for nine of the same PFCs. Total PFCs (almost completely PFCAs) at one of these PWS located near an industrial source of PFCs were higher than in any other PWS tested (up to 330 ng/L). These results show that multiple PFCs are commonly found in raw water from NJ PWS. Future work is needed to develop approaches for assessing the potential human health risks of exposure to mixtures of PFCs found in drinking water and other environmental media.
Here, the performance and mechanism of pollutant removal in the Zhoucun reservoir by water-lifting and aeration systems (WLAs) were explored. The hypolimnion anoxic layer disappeared and the ...reservoir was mixed after the WLAs were operated for approximately 35 days, providing a suitable environment for pollutant removal. Operation of the system enhanced the metabolic activity of the water microbes and their capacity for purification, which contributed to the removal of nitrogen, organic carbon, Fe, Mn, P, and S. Specifically, the total N concentration decreased from 2.55 to 0.48 mg/L, showing an 81.18% removal rate. Microbial metabolism and the diversity index increased following the operation of the WLAs in the Zhoucun Reservoir. Furthermore, the water reservoir clearly inhibited the performance of Fe, Mn, P, and S through the WLA operation, meeting the requirements for class III based on the Chinese Surface Water Environmental Quality Standard (GB3838–2002). High-throughput sequencing analysis revealed increased levels of indicator and keystone operational taxonomic units belonging to Flavobacterium, hgcI_clade, Rheinheimera, Dechloromonas, Pseudomonas, and Rhodocyclaceae, which are related to the degradation of organic carbon and removal of nitrogen and phosphorus. Moreover, total N, ammonia, total P, dissolved oxygen, temperature, and pH were the principal factors affecting the microbial community based on redundancy analysis and the Mantel test. Furthermore, network analysis showed that symbiotic relationships accounted for the major proportion of the microbial network. Our results provide a theoretical foundation for the efficiency of N removal and essential technical support for improving the self-repair capacity of water in drinking water reservoirs.
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•Nitrogen, organic carbon, Fe, Mn, P, and S is efficiently removed by WLAs.•Indicator OTU and keystone OTU belonged to Flavobacterium, hgcI_clade, Rheinheimera, Dechloromonas, Pseudomonas, and Rhodocyclaceae.•TN, Ammonia, TP, DO, T, and pH were the principal factors shaping the microbial community.
This study was performed to validate the shelf life of commercial sachet‐packed drinking water produced in the Benin City metropolis, Edo State, Nigeria. Seven brands of sachet‐packed water that were ...freshly produced by manufacturers were collected from respective factories and subjected to standard physicochemical and microbial tests. The colour of all water brands (0·0–5·6 HU) was within the limits recommended by the World Health Organization (WHO) (≤15 HU) while the temperature (26·9–28·4°C) was above the limits recommended by WHO (≤25·0°C). The pH reported in brands 1 and 6 at week 8 of storage was below WHO recommended limits (6·5–9·5). At week 8 of storage, brands 1 and 6 had HPC (3·97–4·70 log10 CFU per ml) that were above WHO/National Agency for Food and Drug Administration and Control (NAFDAC) recommended limits (≤2 log10 CFU per ml) while TCC (<1 MPN 100 ml−1) in all brands were within recommended limits (≤10 MPN 100 ml−1). No thermo‐tolerant Coliforms and Cryptosporidium were present in all brands; though, Streptococcus faecalis was detected in brand 6. Based on WHO/NAFDAC specifications for the examined parameters, brands 1 and 6 were inferred to not comply with the recommended shelf life of 2 months (approximately 8 weeks). Hence, there is a need for strict compliance to NAFDAC‐specified Good Manufacturing Practice by these processing factories to prevent probable adverse health effects.
Significance and Impact of the Study: In Nigeria, there is a dearth of information on the shelf life compliance status of commercially packaged drinking water as specified by the National Agency for Food and Drug Administration and Control (NAFDAC). Based on the NAFDAC specification of 2 months (approximately 8 weeks) shelf life for sachet‐packed drinking water, there is a 29% likelihood of non‐shelf life compliance amongst processing factories in Benin City Metropolis, Nigeria.
Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water ...quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R2 > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe3O4) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe3O4. The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe6(OH)12CO3 content under higher sulfate concentrations.
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•Sulfate could trigger heavy metal release from iron corrosion scales.•Strong correlations exist between the releases of total iron and heavy metals.•Heavy metals release decrease slowly over time after sudden increase by sulfate.•Corrosion scale stabilization and SRB growth inhibit heavy metals release.
A novel adsorbent of sulfate-doped Fe3O4/Al2O3 nanoparticles with magnetic separability was developed for fluoride removal from drinking water. The nanosized adsorbent was characterized and its ...performance in fluoride removal was evaluated. Kinetic data reveal that the fluoride adsorption was rapid in the beginning followed by a slower adsorption process, nearly 90% adsorption can be achieved within 20 min and only 10–15% additional removal occurred in the following 8 h. The fluoride adsorption isotherm was well described by Elovich model. The calculated adsorption capacity of this nanoadsorbent for fluoride by two-site Langmuir model was 70.4 mg/g at pH 7.0. Moreover, this nanoadsorbent performed well over a considerable wide pH range of 4–10, and the fluoride removal efficiencies reached up to 90% and 70% throughout the pH range of 4–10 with initial fluoride concentrations of 10 mg/L and 50 mg/L, respectively. The observed sulfate–fluoride displacement and decreased sulfur content on the adsorbent surface reveal that anion exchange process was an important mechanism for fluoride adsorption by the sulfate-doped Fe3O4/Al2O3 nanoparticles. Moreover, a shift of the pH of zero point charge (pHPZC) of the nanoparticles and surface analysis based on X-ray photoelectron spectroscopy (XPS) suggest the formation of inner-sphere fluoride complex at the aluminum center as another adsorption mechanism. With the exception of PO43−, other co-existing anions (NO3−, Cl− and SO42−) did not evidently inhibit fluoride removal by the nanoparticles. Findings of this study demonstrate the potential utility of the nanoparticles as an effective adsorbent for fluoride removal from drinking water.
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•The adsorbent is an alumina-coated magnetite nanoparticles with sulfate doping on the surface.•The adsorption capacity of the adsorbent for fluoride was calculated as 70.4 mg/g.•This nanoadsorbent with high pHPZC performed well over a considerable wide pH range of 4–10.
Iodized table salt provides iodide that is essential for health. However, during cooking, we found that chloramine residuals in tap water can react with iodide in table salt and organic matter in ...pasta to form iodinated disinfection byproducts (I-DBPs). While naturally occurring iodide in source waters is known to react with chloramine and dissolved organic carbon (e.g., humic acid) during the treatment of drinking water, this is the first study to investigate I-DBP formation from cooking real food with iodized table salt and chloraminated tap water. Matrix effects from the pasta posed an analytical challenge, necessitating the development of a new method for sensitive and reproducible measurements. The optimized method utilized sample cleanup with Captiva EMR-Lipid sorbent, extraction with ethyl acetate, standard addition calibration, and analysis using gas chromatography (GC)–mass spectrometry (MS)/MS. Using this method, seven I-DBPs, including six iodo-trihalomethanes (I-THMs) and iodoacetonitrile, were detected when iodized table salt was used to cook pasta, while no I-DBPs were formed with Kosher or Himalayan salts. Total I-THM levels of 11.1 ng/g in pasta combined with cooking water were measured, with triiodomethane and chlorodiiodomethane dominant, at 6.7 and 1.3 ng/g, respectively. Calculated cytotoxicity and genotoxicity of I-THMs for the pasta with cooking water were 126- and 18-fold, respectively, compared to the corresponding chloraminated tap water. However, when the cooked pasta was separated (strained) from the pasta water, chlorodiiodomethane was the dominant I-THM, and lower levels of total I-THMs (retaining 30% of the I-THMs) and calculated toxicity were observed. This study highlights an overlooked source of exposure to toxic I-DBPs. At the same time, the formation of I-DBPs can be avoided by boiling the pasta without a lid and adding iodized salt after cooking.
China has been suffering from endemic fluorosis for the past 30 years. This study investigated fluoride concentrations in 10 districts of Tianjin, China, to illustrate their spatial distribution ...characteristics and potential human health risks. The results showed fluoride concentration of 0.01–6.30 mg L−1 with a mean value of 0.99 mg L−1, and 78.82% of water fluoride reaches the standard for drinking water (1.5 mg L−1). Higher fluoride levels were recorded in deep well pumps supply zones, and more potential changes in fluoride occurred was positively correlated with pH in groundwater. Mean value of fluoride in drinking water in 10 districts followed the order of WQ > BC > JZ > NH > BD > BH > JN > JH > DL > XQ. Estimations of non-carcinogenic risk for drinking water indicated that mean hazard quotient values of fluoride for combined pathways (i.e., oral ingestion and dermal absorption) were >1.0 for all age groups of WQ and BC. The results also showed that the estimated risk primarily came from the ingestion pathway. Risk levels for children varied obviously, generally in the order of 1-4y > 4-7y > 7-9y (years old). In the central tendency center and reasonable maximum exposure conditions, estimated risks were 1.25, 1.12, 0.771 and 3.66, 3.29, 2.27, respectively. The results supply material information for health authorities in fluorosis areas to put forward more efficient policies to control the endemic diseases. Attention should be paid to the formulation of health promotion strategies and measures to reduce fluoride intake in order to protect the health of residents.
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•Fluoride content in drinking water for fluorosis areas in Tianjin was investigated.•MWS system has a better effect on reducing water fluoride concentration.•Younger children (1–4 years old) are more vulnerable to high fluoride exposure.•Special attention should be paid to health education strategies against fluorosis.
The disinfection of drinking water is a major public health achievement; however, an unintended consequence of disinfection is the generation of disinfection by-products（DBPs）. Many of the identified ...DBPs exhibit in vitro and in vivo toxicity, generate a diversity of adverse biological effects, and may be hazards to the public health and the environment.Only a few DBPs are regulated by several national and international agencies and it is not clear if these regulated DBPs are the forcing agents that drive the observed toxicity and their associated health effects. In this study, we combine analytical chemical and biological data to resolve the forcing agents associated with mammalian cell cytotoxicity of drinking water samples from three cities. These data suggest that the trihalomethanes（THMs） and haloacetic acids may be a small component of the overall cytotoxicity of the organic material isolated from disinfected drinking water. Chemical classes of nitrogen-containing DBPs, such as the haloacetonitriles and haloacetamides, appear to be the major forcing agents of toxicity in these samples. These findings may have important implications for the design of epidemiological studies that primarily rely on the levels of THMs to define DBP exposure among populations. The TIC-Tox approach constitutes a beginning step in the process of identifying the forcing agents of toxicity in disinfected water.
After having produced drinking water of high quality it is of vital interest to distribute the water without compromising its quality neither by recontamination nor by microbial regrowth. To minimize ...regrowth, the strategy of distributing biostable water is followed in several European countries. This implies on one hand the production of water that has a low level of growth-supporting nutrients, in particular organic carbon compounds, and, on the other hand, using materials for storage/distribution that have a low biofilm formation potential and from which only low amounts of total organic carbon (TOC) leach into the water phase. Currently, the approval of materials in contact with drinking water relies on two tests, a migration test and a biofilm formation test. Here we describe an extended migration testing procedure that allows to obtain information not only on the amount of chemical compounds but also on the amount of growth-supporting compounds leaching into the water. In short, the test developed combines several migration cycles and subsequent measurement of the TOC with a novel, fast and reliable test method for determining the assimilable organic carbon (AOC) in the migration waters. AOC gives an indication on the growth-supporting properties of the material. Thus, an initial characterisation of a material with respect to its suitability for usage in contact with drinking water can be performed in a single assay. Results obtained with the new assay for a number of materials typically used in drinking water and sanitary installations are reported.
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► A new test procedure for the release of compounds from plastic materials is described. ► It includes measurement of growth and biofilm formation supporting AOC. ► The test gives information on biodegradability of compounds released by plastics. ► The test allows assessing influence of plastic materials on water biostability.
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