WHO Standards For Drinking Water Research Articles

Drinking water quality assessment according to water quality index and health risk assessment: а case study of Pedro Vicente Maldonado canton, Ecuador

The effluent water quality of a treatment plant in a canton of Ecuador according to water quality index (WQI) and health risk assessment was investigated in this study. The quality of the influent and effluent water of the treatment plant was monitored monthly from January 2017 to December 2019. Physicochemical and microbiological parameters, such as temperature, pH, turbidity, color, suspended solids, electrical conductivity, free chlorine, nitrates, nitrites, ammonia nitrogen, sulfates, fluorides, manganese, iron, fecal coliforms and total coliforms were determined. To evaluate the impacts of studied water on human health, health risk assessment for non-cancerogenic elements, including hazard index (HI) and risk of olfactory-reflex effects for organoleptic indicators were performed in accordance with Russian and foreign guidelines. Water quality parameter results were compared with WHO drinking water standards, revealing that the influent was contaminated microbiologically and other parameters such as color, turbidity, and iron were also above the limit values. The WQI results showed that water after purification is suitable for drinking (I class - excellent). Hazard Index (HI) results showed that the non-carcinogenic substances studied had a low risk for both adults and children (1). Additionally, the risk of olfactory-reflex effect was characterized as acceptable for all the collected purified water samples.

Design of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate-polyacrylamide dual network hydrogel for long-term stable, highly efficient solar steam generation

Photothermal materials have attracted significant interests for interfacial solar steam generation towards desalination or sewage purification. However, despite recent encouraging progress, the development of long-term stable photothermal materials with high overall performance is still one of the major hurdles to realize scalable practical usage. Herein, we develop a dual network hydrogel of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and polyacrylamide (PAAm) for interfacial solar steam generation via one-step radical polymerization and chemical cross-linking of acrylamide within viscous PEDOT:PSS nanofibril dispersion. As-obtained PEDOT:PSS-PAAm hydrogel exhibits a unique combination of advantageous evaporation performances including excellent sunlight absorption (∼99.8%), fast steam generation rate (2.15 kg m-2 h-1), and high energy efficiency (∼97.2%), comparable to the state-of-the-art photothermal materials. Furthermore, the PEDOT:PSS-PAAm hydrogel also displays fascinating mechanical properties like softness (Young’s modulus: 38 ∼ 86 kPa), stretchability (fracture strain: >80%), and nice mechanical stability against varying deformations, guaranteeing its potential usage in harsh practical application environment. Toward real water purification applications, such a hydrogel is demonstrated to possess excellent long-term stability with an average energy efficiency of 94.8% and anti-salt-fouling properties against 30-day continuous outdoor exposure, superior to most previously reported photothermal materials. We further demonstrate PEDOT:PSS-PAAm hydrogel-integrated solar steam generator for practical desalination and sewage purification, and the generated water can reach the WHO drinking water standards for metal cations/organic pollutants.

The Land–Water–Energy Nexus of Ruzizi River Dams (Lake Kivu Outflow, African Great Lakes Region): Status, Challenges, and Perspectives

Hydroelectric power (HP) represents the main source of electricity in Africa, including the Democratic Republic of Congo. The demand for new dam construction is high, and major projects are currently progressing through planning and implementation stages. New HP dams should comply with both past and emerging environmental requirements. River systems need water to maintain hydraulic and ecological functions. Flow regime disturbance can prevent rivers from providing their ecosystem services and disrupt riparian communities. Most dammed rivers in Africa are understudied, however, in terms of their environmental flow requirements. This study analysed the hydrological regime and water quality of the Ruzizi River. The research investigated conditions of minimum water flow and hydropeaking at the Ruzizi I HP dam in terms of land management constraints and ecological impacts. According to Gumbel’s hydrological model, a discharge of ∼130 m3/s showed the longest return period (12 years) among the most recurrent flows. By contrast, the maximum recorded discharge of 143 m3/s showed a return time of 76 years. Any discharge between 46 and 120 m3/s could occur at any time within three years. The discharge–hydropower production relationship for the power plant provided a possible minimum environmental flow of 28 m3/s (i.e., 25%). Drinking water quality was assessed according to WHO water quality index (WQI) standards. Turbidity (i.e., total suspended solids) upstream and downstream of dams correlated strongly with rainfall (r = 0.8; n = 12) and land use. WQI values observed in excess of WHO drinking water standards indicate that the Ruzizi River is currently unsuitable for drinking water purposes.

Atmospheric Water Generator (AWG): New Innovative Technology to Overcome Global Water Scarcity

Freshwater scarcity is an ever-growing concern for human society. The atmosphere contains water in the form of water vapor; moisture etc., within that amount almost 35% of the water is wasted. Alternative new technologies are urgently needed to overcome the rapidly increasing global water scarcity. Atmospheric water is a potential source of potable water, as the earth’s atmosphere contains tons of fresh water (98% in a vapor state). The atmospheric water generator (AWG) converts water vapor into liquid water and is a capable solution for water scarcity. The major aim of this research work is to provide safe and clean drinking water to those areas which are facing water scarcity problems. In this research work we provide the comprehensive analysis of the chemical and biological profiles of water, produced for several months by three different AWG. Physical parameters, heavy metals and microbiological parameters were analyzed in the water. The main elements found were aluminum, calcium, magnesium, and potassium. The sampling site, likely affected the chemical composition of the produced atmospheric water. Nevertheless, the produced water nearly always met the WHO drinking water standards. In this research work, scientific evidence has been presented that supports, AWG can be an alternative potential source of water to cope up with water scarcity problem and provide safe drinking water throughout the year.

New Schiff base probe for the fluorometric turn-on sensing of Cd2+ ions and bio-imaging application

We report herein a new 4-Cyanobiphenyl-based Schiff base probe, BPC for efficient fluorometric detection of highly hazardous Cd2+ ions. BPC can sense Cd2+ through selective turn-on fluorescence responses in CH3CN/H2O (3:2, v/v; Tris-HCl, pH = 7.4) solution. The 1:1 complex formation between BPC and Cd2+ could block both isomerization of CN and excited-state intramolecular proton transfer (ESIPT) process and meanwhile enhance the molecular rigidity, resulting in chelating enhanced fluorescence (CHEF). The detection limit (10.5 nM) is lower than the WHO drinking water standard (26.7 μM), which renders BPC a likely candidate for sensing of Cd2+ ions in neutral aqueous media. The analytical applicability of BPC for Cd2+ has been tested on the test paper strips. In addition, BPC was applied to image Cd2+ in living HeLa cells and zebrafish.

Evaluation of polluted urban river water quality: a case study of the Xunsi River watershed, China.

Urbanization has caused severe negative impacts on intra-urban river water bodies. In this paper, 22 physicochemical parameters were measured at 20 locations in the level period and 29 locations in the wet and dry period using nearby urban area surface water samples from a medium-sized polluted river (a lake-river continuum, i.e., Xunsi River, Qingling River and Tangxun Lake) in the Yangtze River watershed in Wuhan, China. In this study, the environmental quality standards for surface water of China (GB3838-2002) and the WHO drinking water standard (2011) were used as reference standards. After the basic physicochemical parameters were evaluated, the possible sources of pollution in the study area under urban pressure were examined by applying multivariate statistical techniques. The factor analysis method and entropy weighting method identified three critical factors describing the type of surface water pollution in the watershed: (1) pollution from nutrients, mainly nitrogen pollution, (2) trace metals pollution, mainly from Fe and Pb, and (3) organic pollution. Based on multivariate analysis, the weighted arithmetic water quality index (WQI) was used to assess the water quality of each period. The WQI results show that the water near the urban area of the watershed temporally shows light to moderate pollution overall in the level and wet periods, and sever pollution in the dry period. The worst water quality indicating water that is not suitable for any practical use occurs in the dry period. Spatially distributed in clusters and strips visualized in kriging method, the water quality of the lake source and upstream is better than that of the downstream. In addition, Escherichia coli was detected at consistently high levels, and although the river is not a source of drinking water, it could pose a threat to downstream waterworks.

Microbiological examination of bottled and sachet water sold and consumed in Nnewi Metropolis, Anambra State, Southeast Nigeria

Microbiological examination of bottled and sachet water sold and consumed in Nnewi metropolis, Anambra State, Southeast Nigeria was carried out to assess their microbiological qualities. The bottled and sachet water were bought from various sales outlets in Nnewi, Nnobi, Ichi and Ozubulu towns. Overall 45 samples belonging to 15 different brands (5 bottled table and 10 sachet water) were analyzed for their microbiological quality using standard microbial methods in triplicates of each brand. The biochemical characteristics of the isolates were studied and results showed varied degrees of microbial load which indicated Pseudomonas spp., Klebsiella spp., Staphylococcus aureus, Bacillus spp., Salmonella spp., Enterobacter spp. and Citrobacter spp. Of all the 15 sachet water brands analyzed, 40 % failed to meet the WHO drinking water standard of ten coliform per 100 mL, making them unsuitable for human consumption, but all the bottled water samples were of potable quality. The bottled water samples had more microbiological quality than the sachet water samples. The contaminated sachet water samples are not fit for human consumption. Causes of contamination of the water samples and recommendations for improving their microbiological quality were highlighted.

Humic acid-coated hydrated ferric oxides-polymer nanocomposites for heavy metal removal in water

Water pollution by toxic heavy metals poses a threat to the environment and human bodies. Herein, a novel hydrated ferric oxide nanoparticle (HFO) based hybrid adsorbent was fabricated for the removal of toxic Cu(II), Cd(II) and Pb(II) from water. HFOs were immobilized into a porous resin D-201, and then this nanocomposite HFO-D201 was coated with humic acid (HA) to enhance the binding sites of target metals. Both HFOs and HA contribute to the sequestration of heavy metals. The as-synthesized hybrid adsorbent HA-HFO-D201 exhibited excellent performance on the removal of Cu(II), Cd(II), and Pb(II) in a pH range of 3–9, while no Fe leaching was observed. The presence of natural organic matter (20 mg C/L) has limited influences on the adsorption, and more than 85% of the target metals can be removed after treatment. HA-HFO-D201 showed preferable adsorption toward Cu(II) and Pb(II) (1 mg/L) from the background Ca2+ solution at much higher concentrations (100 mg/L), while the retention of Cd(II) (1 mg/L) decreased to some extent. Fixed-bed column experiments exhibited that the treatment capacities of HA-HFO-D201 are 90 bed volumes (BV) for Cd(II), 410 BV for Pb(II) and > 800 BV for Cu(II) of simulated contaminated water to meet the WHO drinking water standard. Meanwhile, depleted HA-HFO-D201 can be readily regenerated by a chelating agent Na2EDTA for repeated use. The hybrid adsorbent HA-HFO-D201 has excellent potential to remove heavy metals in water treatment systems.

Spatial analysis and mapping of the groundwater quality index for drinking and irrigation purpose in the alluvial aquifers of upper and middle Cheliff basin (north-west Algeria)

AbstractThe proposed study aims to assess groundwater quality and suitability of the Upper and Middle Cheliff plains (northwest of Algeria) for irrigation and drinking. Here the groundwater is the main source for domestic, agricultural and industrial activities similarly to any other region of the world. The suitability for drinking and for irrigation was evaluated on the basis of water quality index, salinity risk, hardness risk, sodium risk, magnesium risk, permeability index, water infiltration rate, Kelly index and Wilcox and Richards diagrams. The aquifer system is mainly composed of alluvium (gravel, sand, silt, clay, …) from the Mio-Plio-Quaternary. The results of this study highlighted that the majority of the chemical elements analyzed exceed the WHO's drinking water standards and FAO's irrigation water standards. Based on the GroundWater Quality Index (GWQI) results, the Upper and Middle Cheliff groundwater plains shows Doubtful class in most of the plains. In addition, the GroundWater Quality Index for Irrigation (GWQII) shows the predominance of the Good/Permissible groundwater quality class in most of the plains. According to these results, drinking water can cause health problems (a danger) for the human consumption making necessary a proper treatment be able to use it. As for irrigation water, it does not present a danger for irrigating for the vast fields of the region, with the exception of sensitive crops such as: garlic, onion, beans and strawberry. The proposed approach demonstrated to be appropriate in assessing the groundwater quality for irrigation and drinking water supply since it can be easy applicable and suitable in humid, arid or semi-arid regions around the world.

Levels of three heavy metals in ground water and cereals in Chattogram Division, Bangladesh

Heavy metals determination in cereals and vegetables is one of the vital interests, because of their essential or toxic nature. In order to assess the levels and the impact of different toxic metals on human health, a study was carried out to determine the concentration of different toxic metals present in ground water and edible cereals (rice, wheat, and maize), which are grown in Chattogram area of Bangladesh. The concentrations of three heavy metals, Lead (Pb), Chromium (Cr) and Copper (Cu) in ground water and three varieties of cereals were determined by using Atomic Absorption Spectroscopy (AAS). Results on ground water showed that the mean concentrations of Pb content were within the permissible limits in terms of Bangladesh Drinking water standards, but exceeds the WHO Drinking Water Standards (WHODWS), US Environmental Protection Agency Drinking Water Standards (USEPADWS) values. However, Cr and Cu content were within the permissible limits in terms of Bangladesh Drinking water standards, WHODWS and USEPADWS values, respectively. The concentrations of Pb, Cr and Cu in rice ranged from 0.853 to 9.265mg/L, 0.096 to 0.475µg/L and 0.096 to 0.562mg/L; in wheat,from 0.363 to7.523 mg/L, 0.056 to 0.284 µg/L and 0.065 to 0.326 mg/L; in maize, from 0.739 to 8.372 mg/L, 0.058 to 0.248 µg/L and 0.036 to 0.478 mg/L, respectively. Thus, awareness should be raised among the people about the adverse health effects of these metals. The carcinogenic and non-carcinogenic risks of Pb, Cr and Cu for human health is a matter of concern

Comprehensive passive-mode performance analysis on a new multiple-mode solar still for sustainable clean water processing

The solar still is potential to augment clean water supply in the rural and low-income settlements. However, the current efficiency of the device is low. In this study, we report the fabrication and experimental performance analysis of a high-efficiency multiple-mode solar still—tagged Desal-1.5. The solar still was investigated in passive mode, relying entirely on natural insolation. Both desalination and ordinary water purification experiments were conducted on the device using seawater and moderately polluted lake water, respectively, between 09:00 and 18:00 h of Malaysia's tropic weather. The optimum freshwater yield of the prototype within the interval was 5780.5 ml/m2, while the optimum solar-to-vapor conversion efficiency, evaluated using the transient latent heat of vaporization, was 161.4%. Furthermore, for the first time on a solar still geometry, condensate loss due to condensate collection channel slope has been estimated in this study for our Desal-1.5. The loss amounted to 18.5% of the actual condensate collection. Eventually, water quality assessments of distillates from the device showed good compliance with both WHO and Malaysian drinking water standards. Thus, the recommendation of the solar still to ameliorate freshwater scarcity and support sustainable clean water provision in the rural and low-income regions is strengthened.

In-situ forming Sub-2 nm hydrous iron oxide particles in MOFs for deep-treatment and high anti-interference in arsenic removal

An adsorbent with deep-treatment ability and high selectivity for arsenic removal is strongly in need in water treatment. A new composite structure combining ultrasmall (sub-2 nm) nanoparticles (NPs) with metal–organic frameworks (MOFs) has been prepared here. In this structure, ultrasmall (sub-2 nm) hydrous ferric oxide nanoparticles (HFeO) were in-situ generated inside a Fe-based MOF (MIL-100) through a room-temperature reduction process. The structure, denoted as HFeO@MIL-100, demonstrates extraordinary adsorption ability for As (V), with a high capacity and more than 20 times faster kinetics than that of MIL-100. More importantly, it can deeply treat As (V) in contaminated water from 3900 μgL−1 to 5 μg L−1, directly meeting the WHO drinking water standard (<10 μg L−1). And due to the size-exclusion effect of uniform micropores originated from MOFs, the structure performs high anti-interference ability in As (V) adsorption, maintaining more than 97% capacity even within abundant competitive ions or species, such as humic acid, silicate and sulfate ions.

High-performance TFNC membrane with adsorption assisted for removal of Pb(II) and other contaminants

Rapid and thorough removal of heavy metal ions in wastewater is critical for the urgent need of clean water. Herein, we prepared a high-performance thin film nanofibrous composite (TFNC) membrane consisting of a polyacrylonitrile (PAN)-UiO-66-(COOH)2 composite nanofibrous substrate (CPAN) and a calcium alginate (CaAlg) skin layer. Owing to abundant adsorption sites of UiO-66-(COOH)2 MOF, the optimal CPAN-2 nanofibrous substrate showed excellent adsorption capacity for lead ions. The maximum Pb2+ adsorption capacity of CPAN-2 substrate calculated by Langmuir isotherm model was 254.5 mg/g. Meanwhile, due to the relatively loose structure of CaAlg skin layer, this TFNC membrane showed high water permeate flux about 50 L m−2h−1 at 0.1 MPa, and the rejection for dyes was higher than 95%. Therefore, CaAlg/CPAN TFNC membranes were appropriate for dynamic adsorption/filtration to remove Pb2+. Compared with original CaAlg/PAN membrane, the optimal CaAlg/CPAN TFNC membrane showed much better ability to treat Pb(II)-containing wastewater and had good recyclability. Most importantly, the CaAlg/CPAN TFNC membrane could treat 7659 L m−2 wastewater containing single lead ions under WHO drinking water standard, and effectively deal with more simulated lead-containing wastewater. This work could provide a substitutable solution for effective removal of heavy metal ions and other various contaminants in wastewater.

Water, sanitation, and hygiene in healthcare centres: appraisal in a pandemic

Abstract Assessment of water, sanitation, and hygiene (WASH) facilities in Primary Healthcare Centres (PHCs) and water source quality in parts of Southwestern Nigeria was conducted. Sixty-one PHCs in urban and rural areas were selected using a stratified random sampling technique. A WASH profile of the PHCs was conducted based on the water source type, type of toilet facilities, and handwashing practice using the Joint Monitoring Programme service ladder for monitoring WASH services in healthcare facilities. Water sources were tested for pH, electrical conductivity, total dissolved solids, turbidity, chloride, nitrate, and E. coli. Boreholes and hand-dug wells are the most prevalent water source type, and flush toilets and pit latrines are the major types of toilet facilities used. All but two PHCs engaged in handwashing practices. Water quality analysis results showed that chloride, nitrate, and turbidity were within the WHO drinking-water standards. Poor water quality and sanitation practices could expose health staff and patients to healthcare-associated infections. The study recommends the construction of safe, secure and accessible water sources and toilet facilities, provision of water treatment facilities, and the training of staff and patients on the significance of handwashing practices.

Low-cost laterite-laden household filters for removing arsenic from groundwater in Vietnam and waste management

This study evaluated the performance of a low-cost natural laterite from Thach That (NLTT), Vietnam, for its capacity to remove arsenic (As) in a household filter with contaminated groundwater. The NLTT was initially tested in a laboratory column trial lasting 800 h. The breakthrough curves were found to fit the Thomas model very satisfactorily with adsorption capacities of 0.06 and 0.20 mg/g at a flow velocity of 0.85 m/h for the influent As(V) concentrations of 0.1 and 0.5 mg/L, respectively. In household filters at four sites, the median As concentration in groundwaters (0.04–0.19 mg/L) dropped to 0.026–0.054 mg/L after traditional sand filtration. However, following subsequent NLTT filtration through columns (14 cm inner diameter, 65 cm height) at 0.65 m/h flow velocity, it fell to below the Vietnam and WHO drinking water standard (0.01 mg/L) during seven months of continuous operation. Portland cement and lime were tested as binding agents for the exhausted NLTT waste in a solidification/stabilization process at different ratios. The best ratio of exhausted NLTT: Portland cement: lime for restraining mobility of As from this waste was 3:1:0.5. The concrete brick products exhibited a suitable compressive strength for using it as building materials in construction work.

Hydrogeology and origin of waters of the Panyam Volcanic Line springs, Jos Plateau, Nigeria

The PVL springs are used for both domestic and agricultural purposes. The seepage from the springs has resulted in producing a large expanse of wetlands and is therefore intensively use for dry season farming. The aim of this study was to determine the hydrogeological, hydrochemical characteristics, origin and their suitability for domestic and irrigation. The hydrogeology of the springs was determined by field mapping. The physico-chemical parameters were determined in the field and by laboratory methods. For the cation and anion analysis the ICP-MS and the wet methods were employed respectively. The stable isotope composition of oxygen (δ18O) and hydrogen (δ2H) were analyzed by Isotope Ratio Mass Spectrometer. The hydrochemical analysis revealed that the PVL springs waters are generally neutral with an average pH value of 7.3. The average TDS and EC values are 127.8mg/l and 246µs/cm respectively. These values fall within fresh water class. The average Mg2+,Ca2+, Na+ and K+ cation concentration values are 16.3mg/l, 15.8mg/l, 10.8mg/l and 5.58mg/l respectively. The average anions concentration of HCO3-, SO4 and Cl- are 140mg/l, 8.6mg/l and 3.4mg/l respectively. Piper trilinear diagram show that the spring waters is predominantly Mg-Ca-HCO3 water type with potable qualities based on WHO drinking water standards. The sodium Adsorption Ratio (SAR) and Sodium Soluble Percentage (SSP) values range between 0.44 to 0.84 and 26.4 to 54% respectively and falls within irrigation quality standards. Stable isotope compositions of δ18O and δ2H ranges from -3.60/00 to -4.90/00 and -200/00 to -280/00 respectively falls within the meteoric water composition. This is further affirmed by the δ2H versus δ18O plot on the correlation diagram with Standard Meteoric Water Line.

Hydrogeology and origin of waters of the Panyam Volcanic Line springs, Jos Plateau, Nigeria

The PVL springs are used for both domestic and agricultural purposes. The seepage from the springs has resulted in producing a large expanse of wetlands and is therefore intensively use for dry season farming. The aim of this study was to determine the hydrogeological, hydrochemical characteristics, origin and their suitability for domestic and irrigation. The hydrogeology of the springs was determined by field mapping. The physico-chemical parameters were determined in the field and by laboratory methods. For the cation and anion analysis the ICP-MS and the wet methods were employed respectively. The stable isotope composition of oxygen (δ18O) and hydrogen (δ2H) were analyzed by Isotope Ratio Mass Spectrometer. The hydrochemical analysis revealed that the PVL springs waters are generally neutral with an average pH value of 7.3. The average TDS and EC values are 127.8mg/l and 246µs/cm respectively. These values fall within fresh water class. The average Mg2+,Ca2+, Na+ and K+ cation concentration values are 16.3mg/l, 15.8mg/l, 10.8mg/l and 5.58mg/l respectively. The average anions concentration of HCO3-, SO4 and Cl- are 140mg/l, 8.6mg/l and 3.4mg/l respectively. Piper trilinear diagram show that the spring waters is predominantly Mg-Ca-HCO3 water type with potable qualities based on WHO drinking water standards. The sodium Adsorption Ratio (SAR) and Sodium Soluble Percentage (SSP) values range between 0.44 to 0.84 and 26.4 to 54% respectively and falls within irrigation quality standards. Stable isotope compositions of δ18O and δ2H ranges from -3.60/00 to -4.90/00 and -200/00 to -280/00 respectively falls within the meteoric water composition. This is further affirmed by the δ2H versus δ18O plot on the correlation diagram with Standard Meteoric Water Line.

Performance of inclined plates settler integrated with constructed wetland for high turbidity water treatment

Abstract The purpose of this study was to investigate and demonstrate cost-effective treatment technologies for highly turbid waters, used for domestic purposes in rural areas of Tanzania where conventional community water treatment techniques are not available. Pilot-scale inclined plates settler integrated with constructed wetland (IPS-CW) system was investigated on earth dam water with turbidities ranging from 186 to 4,011 NTU. The IPS was used as a physical pretreatment system preceding the CW, meant for the removal of organic matter, nutrients, and pathogens. Major focus of the IPS-CW system was on turbidity and faecal coliform (FC) removal, and at 5 L/min flow rate mean maximum removal efficiencies of 95.9% and 94.3% were achieved, respectively. Total suspended solids, nitrate (NO3−), ammonium, biological oxygen demand (BOD5) and phosphate removal were studied and removal efficiencies of 97.4%, 91.7%, 71.3%, 91.7% and 49.8% were obtained at 5 L/min flow rate, respectively. Although the use of these combinations of technologies in improving drinking water quality is uncommon, results demonstrated that NO3− and BOD5 met WHO and TBS drinking water standards of ≤50 mg/l and ≤6 mg/L respectively. Due to low production cost and simplicity in operation, the system is relevant for application in rural communities.

Implications of irrigation water quality on shallow groundwater in the Nile Delta of Egypt: A human health risk prospective

Groundwater is the main source for drinking in Egypt, especially in rural communities; however, water quality of shallow aquifers is more susceptible to human activities. The current work aimed at evaluating groundwater quality for drinking and associated health risks in an area of the Nile Delta (30° 14 ″ 47 ″ to 30° 17′ 51 ″ N and 31° 17′ 38 ″ to 31° 20′12 ″ E) in response to irrigation water quality. Thirty groundwater samples were collected from three irrigated sites (ten samples from each site); the Nile freshwater (NFW), the agricultural drainage water (ADW), and mixed wastewater (MWW) irrigated sites. Overall, ranges of pH, Ca 2＋ , Mg 2 + , F − , NO 3 − , Cu, Mn, Ni, and Zn were within the permissible levels according to Egypt and WHO drinking water standards, while the count of total and fecal coliform bacteria exceeded safety limits. The water quality index indicated that samples from the NFW-, ADW- and MWW-irrigated sites had moderate to good, low, and low to moderate qualities, respectively. On average, the hazard index (HI) indicated no potential non-cancer risk for adults (HI < 1.0) in the three sampling sites, while children in the MWW-irrigated sites would suffer adverse health risks (HI > 1.0). The mean total cancer risk (TCR) was in the acceptable range (1.0 × 10 −6 to 1.0 × 10 −4 ) for adults in two sites (the NFW- and ADW-irrigated sites), while adults in the MWW-irrigated sites and children in all sampling sites would suffer cancer risks over the lifetime (TCR > 1.0 × 10 −4 ). The potential cancer risk would be mainly due to Ni exposure via the oral route, and thus further management studies should be considered to mitigate the adverse effects. This study would provide a useful database for decision and policymakers for protecting shallow groundwater quality and reduce potential human health risks.

Evaluation of Heavy Metals in Drinking Water Resources in the Department of Nyan, Province of Logone Oriental in Chad

The present research work was carried out in the Department of Nyan, Province of Logone Oriental. It allowed the quantification of heavy metal contents in well, borehole and river water intended for human consumption. Samples from these water sources were collected and submitted for laboratory analysis. Structural quality indicators such as pH, temperature, electrical conductivity, turbidity, dissolved oxygen and sulphate ions were measured first. The sample was acidified and the measurement is then performed on the metals, i.e. barium, calcium, iron, magnesium, manganese, copper, chromium, aluminium, lead, strontium, tin, zirconium and titanium. The results of the quality indicators showed that well and borehole waters have an acidic pH; their average measured values are 5.34±0.24 and 5.48±0.15 respectively. Well water and that of rivers have high turbidity values averaging 43.40±1.21 NTU and 47.56±1.5 NTU respectively. With respect to metals, some have values above the WHO drinking water standards. These include iron, which has high values in well water (7.890±0.016 mg/L) and river water (0.866±0.003 mg/L), manganese in well water (0.093±0.001 mg/L), aluminum in well water (5.614±0.009 mg/L) and river water (1.211±0.008 mg/L). Based on these results, consumption of these water sources would expose communities to mild or chronic health risks.