Identifying the Hydrochemical Characteristics,Genetic Mechanisms and Potential Human Health Risks of Fluoride and Nitrate Enriched Groundwater in the Tongzhou District,Beijing,North China

Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas and economic hubs.This study focuses on the high F^(−)and NO_(3)^(−)concentration groundwater in Tongzhou District,Beijing,North China.A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics,elucidate genetic mechanisms and evaluate the potential human health risks.The results of the analysis indicate:Firstly,most of the groundwater samples are characterized by Mg-HCO_(3) and Na-HCO_(3) with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471-2337 mg/L.The NO_(3)^(−)concentration in 38.89%groundwater samples and the F^(−)concentration in 66.67%groundwater samples exceed the permissible limited value.Secondly,F^(−)in groundwater originates predominantly from water-rock interactions and the fluorite dissolution,which is also regulated by cation exchange,competitive adsorption of HCO_(3)−and an alkaline environment.Thirdly,the effect of sewage disposal and agricultural activities have a significant effect on high NO3-concentration,while the high F^(−)concentration is less influenced by anthropogenic activity.The alkaline environment favors nitrification,thus being conducive to the production of NO_(3)^(−).Finally,the health risk assessment is evaluated for different population groups.The results indicate that high NO_(3)^(−)and F^(−)concentration in groundwater would have the largest threat to children’s health.The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.

Arsenic and fluoride co-enrichment of groundwater in the loess areas and associated human health risks:A case study of Dali County in the Guanzhong Basin

This study aims to reveal the occurrence and origin of typical groundwater with high arsenic and fluoride concentrations in the loess area of the Guanzhong Basin—a Neogene faulted basin.Key findings are as follows:(1)Groundwater samples with high arsenic and fluoride concentrations collected from the loess area and the terraces of the Weihe River accounted for 26%and 30%,respectively,of the total samples,with primary hydrochemical type identified as HCO_(3)-Na.The karst and sand areas exhibit relatively high groundwater quality,serving as preferred sources for water supply.It is recommended that local governments fully harness groundwater in these areas;(2)groundwater with high arsenic and fluoride concentrations in the loess area and the alluvial plain of rivers in Dali County is primarily distributed within the Guanzhong Basin,which represents the drainage zone of groundwater;(3)arsenic and fluoride in groundwater originate principally from natural and anthropogenic sources;(4)the human health risk assessments reveal that long-term intake of groundwater with high arsenic and fluoride concentrations pose cancer or non-cancer risks,which are more serious to kids compared to adults.This study provides a theoretical basis for the prevention and treatment of groundwater with high arsenic and fluoride concentrations in loess areas.

Efficiency of locally available filter media on fluoride and phosphate removal for household water treatment system

Since conventional water treatment is not affordable in developing countries,looking for locally available and alternative treatment options is mandatory.Removal of fluoride and phosphate can be achieved by designing appropriate filtration media from different materials such as sand,calcined clay,pumice,scoria and bone char.This study was designed to determine the removal efficiency of these locally available filter media with respect to detention time and pH.The filtration apparatuses(tank) were filled separately with stone,gravel with grain size 0.6-4.75 mm and 40 cm deep,sand(ES = 0.15—0.35 mm and UC = 1.5-3),calcined clay,pumice,scoria and bone char with grain size 0.25-0.5 inch.Water samples were prepared using glass bottles with fluoride concentrations of 6 and 8 mg/1 and phosphate concentration of 4 mg/1.Laboratory analysis was carried out before and after filtration to determine the removal efficiency of each medium.It was found that the highest removal of fluoride was achieved by bone char(89.65%),followed by pumice(82.4%).However,bone char has rather increased the concentration of phosphate by 63.8%.Sand was the most efficient media to remove phosphate,managing to remove by 70%.Therefore,it is an attractive option to use these locally available,environmental friendly and appropriate technologies for efficient removal of both fluorine and phosphate at the household or community water treatment level.

Fluoride Excess Removal from Brackish Drinking Water in Senegal by Using KSF and K10 Montmorillonite Clays

Fluoride excess in drinking water is noticed in many countries around the world and particularly in Senegal where, in addition to fluoride excess, high levels of salinity are also encountered. In order to reduce fluoride excess in drinking water in the groundnut basin of Senegal, two types of clays namely montmorillonite KSF and montmorillonite K10 as well were used as adsorbent materials. The results show that the pH which was initially alkaline becomes acidic varying from 2.80 to 6.80. The pseudo first-order kinetic model fit well with the adsorption experiments for KSF montmorillonite (r2 = 0.96), while for K10 clay the same model describe the experiments with slight differences (r2 = 0.90). The KSF clay has a better fluoride adsorption capacity compared to that obtained with K10 clay due to the presence of a great level of calcium oxide in the montmorilonite KSF clay.

Assessing Levels and Health Risks of Fluoride and Heavy Metal Contamination in Drinking Water

A systematic study was carried out to assess the level of contamination with fluorides and heavy metals in the drinking water of the city of Daloa as well as the risks to the health of consumers. The waters of 11.11% of the sites sampled exceeded the fluoride limit for drinking water with a contamination index (CI) greater than 0. All the waters recorded concentrations of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn) and lead (Pb) above the recommended values with CI > 0. However, 22.22% of the sites recorded concentrations below the standard for zinc (Zn) with IC < 0. The assessment of adverse effects on human health showed that the chronic daily intake (CDI) of fluorine and metals was less than 1 (CDI < 1) for both adults and children except for Zn where the CDI > 1 for children in 22.22% of drinking water studied. HQs have an average of less than 1 for fluorine and greater than 1 for all metals. Moreover, the danger indices have values greater than 1. The incremental lifetime cancer risk (ILCR) and the total ILCR are above the recommended values. These results showed that the drinking water sampled is of poor quality due to higher levels of heavy metals, which can constitute a danger to human health. Long-term use of one of these poor quality waters can lead to cancer in consumers. It is therefore necessary to treat this water in order to eliminate the metals before using it for drinking. This study can help decision-makers and competent authorities in charge of water management.

Renewable Energy Powered Membrane Process for Removal of Excess Fluoride Ions and Safe Drinking Water Supply in Rural Areas in Senegal

The analysis results made on drinking water from the rural areas of Kaolack,Diourbel and Fatick central region of Senegal showed the excess of fluoride and chloride ions.Depending on the area,the fluoride concentration in the water can reach 3.5 mg/L.The values obtained are completely above of WHO(World Health Organization)limits.The objective of this study is to assess the performances of membrane filtration units powered by renewable energies for fluoride and salinity excess removal in remote village in Senegal.Many membrane filtration units have been installed in rural areas of regions such as Kaolack,Fatick and Diourbel.These membrane filtration units are equipped by the LPRO(Low Pressure Reverse Osmosis)membranes with 9 m^(2)of surface.A rejection rate of fluoride and chloride ions obtained is 99.33%and 95.25%respectively.The conversion rates are ranged from 45%to 65%.These results clearly show that membrane processes can be used in Africa,especially in isolated rural areas,with the combination of renewable energies.Currently,more than twenty membrane filtration units are installed in Senegal and provide drinking water of very good quality for populations living in rural areas.The prospect is to expand it on a larger scale,which is already underway,with the construction of a desalination plant in Dakar.

Analysis of equilibrium, kinetic, and thermodynamic parameters for biosorption of fluoride from water onto coconut(Cocos nucifera Linn.)root developed adsorbent

Drinking water with higher fluoride levels results in serious irremediable health problems that have attained a startle all over the world.Researches focused towards deflouridation through the application of biosorbents prepared from various plants are finding greater scope and significance.Present research is done on Cocos nucifera Linn.(coconut tree) one of the very commonly available plants throughout Kerala and around the globe.An adsorbent developed from the root portion of C.nucifera Linn.is used in the present study.Equilibrium study revealed that the fluoride uptake capacity is quite significant and linearly increases with initial adsorbate concentration.The adsorption data is analyzed for Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models at varying initial adsorbate concentrations(2–25 mg·L^(-1)).It is found that the adsorption of fluoride onto C.nucifera Linn.root adsorbent follows Langmuir isotherm.Langmuir isotherm constants "a" and "b" obtained are 2.037 mg·g^(-1) and 0.823 L·mg^(-1) at an adsorbent dose of 8 g·L^(-1) and temperature(26 ± 1) ℃.The mean free sorption energy, E obtained, is 9.13 kJ ·mol^(-1) which points out that the adsorption of fluoride onto C.nucifera Linn.root adsorbent is by chemisorption mechanism.The kinetic study also supports chemisorption with adsorption data fitting well with a pseudo-second-order kinetic model with an estimated rate constant K_2 of 0.2935 g·mg^(-1) min at an equilibrium contact time of 90 min.The thermodynamic study indicated the spontaneous and endothermic nature(ΔH =12.728 kJ·mol^(-1)) of fluoride adsorption onto the C.nucifera Linn.root adsorbent.Scanning Electron Microscopy(SEM), BET, FTIR, and EDX methods were used to analyze the surface morphology of adsorbent before and after fluoride adsorption process.Experiments on deflouridation using C.nucifera Linn.root adsorbent application on fluoride contaminated ground water samples from fields showed encouraging results.

Fluoride in Tunisian Drinking Tap Water

This paper presents a fluoride health risk characterization approach to identify the hyper-sensitive population of adverse effect like tooth decay, dental fluorosis and skeletal fluorosis. In this context, a sampling campaign has been done over 100 Tunisian water consumption points (tap). Laboratory analysis results show that the quality of drinking water is affected by high fluoride concentration level exceeding 2 mg·L-1. Over these samples, 7% of them present non-compliant with the Tunisian national standard (NT09.14) and the international guidelines (World Health Organization recommendations, WHO). The overtake cases are located essentially in southern Tunisian areas, i.e. Medenine, Gabes, Gafsa and Tataouine. One can highlight that groundwater, in these southern Tunisian areas, are naturally rich of fluoride. This is because of the aquifers geological and fossil nature. However, commonly northern and central Tunisian areas are characterized by low fluoride concentration level below 0.1 mg·L-1. These undertaken cases don’t meet the water quality requirement defined by WHO.

Preparation of 2D carbon ribbon/Al_(2)O_(3) and nitrogen-doped carbon ribbon/Al_(2)O_(3) by using MOFs as precursors for removing high-fluoride water

2D carbon ribbon/Al_(2)O_(3) was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods.Batch experiments of adsorption parameters such as pH,liquid/solid ratio,adsorption kinetics,adsorption thermodynamics,and anions competitions were investigated to understand the adsorptive behavior of fluoride on carbon ribbon/Al_(2)O_(3) and nitrogen-doped carbon ribbon/Al_(2)O_(3).The adsorption of fluoride on carbon ribbon/Al_(2)O_(3) could be described as the chemical and multilayer adsorption,while the adsorption of fluoride on nitrogen-doped carbon ribbon/Al_(2)O_(3) followed the chemical and monolayer adsorption phenomenon.The fluoride on nitrogen-doped carbon ribbon/Al_(2)O_(3) had a much faster adsorption rate of 3.1×10^(−7) m/s than carbon ribbon/Al_(2)O_(3),which was 1.2×10^(−7) m/s.The nitrogen-doping on carbon ribbon enhances structural defects and improves the adsorption performance of fluoride.Also,the diacetylene linkages(—C≡C—)and pyridinic-N were studied to understand their influences on removing fluoride.The result indicates that carbon ribbon and nitrogen-doped ribbon could serve as good adsorbents for removing fluoride.

Adsorptive Removal of Fluoride from Water by Heat-Treatment Waterworks Alum Sludge

Alum sludge （AS） is a world-wide by-product generated in the drinking water treatment process when aluminum salts are used as coagulant. Its high AI content makes it a potential adsorbent for flouride removal from water. A high performance adsorbent was fabricated via heat treatment of AS and batch adsorption experiments were carried out to investigate its flouride adosroption performance. The results indicated that AS treated at 300℃ （AS300） for 1 h had the highest adsorption capacity for fluoride （52.9% fluoride removal）. The adsorption of fluoride by AS300 fitted better the Langmuir isotherm model than the Freundlich model. The maximum fluoride adsorption capacity of AS300 increased from 4.0 to 9.3 mg/g sludge when reaction temperature increased from 15 to 35 ℃. Thermodynamic parameters showed that the adsorption of fluoride by AS was spontaneous and endothermie. Hence higher temperature was favorable for fluoride adsorption. The adsorption process followed the pseudo-second-order equation. In addition, the fluoride adsorption on AS300 decreased from 4.3 to 2.5 mg/g sludge when the solution initial pH increased from 4.0 to 9.0, which meant that adsorption capacity was greatly dependent upon the initial pH of the solution. The results provide new insight into the resource utilization of AS for fluoride removal.

Occurrence of fluoride in the drinking waters of Langtang area, north central Nigeria

The aim of the study is to assess the occurrence of fluoride in the drinking water sources of Langtang area. Out of the thirty seven water samples collected from drinking water sources (hand dug wells, boreholes, streams and a spring) and analysed. Results revealed that except for fluoride, all other parameters are within the World Health Organisation recommended limits for water consumption. Fluoride in the waters ranges from 0.12 - 10.30 mg/l with a mean of 2.42 mg/l. low levels of fluoride are recorded in the stream samples. However, no clear variations in fluoride content have been observed in both the borehole samples and those from the hand dug wells. Negative correlation exhibited between fluoride and sulphate, fluoride and Phosphate and the poor correlation between fluoride and nitrate, fluoride and chloride rules out the possibility of anthropogenic source of the fluoride in the waters. Positive correlation between lithium and magnesium, and poor but positive correlation between fluoride and lithium indicate that micas within the host rock and the pegmatite may be responsible for leaching fluoride into the waters. Two of the major water types;Ca + Mg-HCO3 and the Na + K-HCO3 water type obtain in the area have good association with fluoride content. Consumption of high fluoride waters clearly manifests in the inhabitant of the area in form of dental fluorosis and bowing of legs especially in children between the ages 7 - 11 years.

Development of a novel nano-biosorbent for the removal of fluoride from water

The study was designed to investigate the use of two sorbents namely(i) Fe3O4 nanoparticles immobilized in sodium alginate matrix(FNPSA) and(ii) Fe3O4 nanoparticles and saponified orange peel residue immobilized in sodium alginate matrix(FNPSOPR) as sorbents for fluoride removal from contaminated water. The synthesized nanoparticles were analyzed and characterized by dynamic light scattering, X-ray diffraction, vibrating sample magnetometry, and scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier transform-infrared spectrometry. The sorbent matrices were prepared in the form of beads and surface functionalized to enable enhanced sorption of fluoride ions. Batch sorption studies were carried out and the sorption isotherm and reaction kinetics were analyzed. Both the sorbents followed Langmuir model of isotherm and fitted well with Pseudo first order reaction. The maximum sorption capacity exhibited by FNPSA and FNPSOPR was58.24 mg·g-1and 80.33 mg·g-1respectively. Five sorption–desorption cycles exhibited 100%, 97.56%, 94.53%,83.21%, and 76.53% of regeneration of FNPSOPR. Accordingly, it is demonstrated that FNSOPR could be used as a promising sorbent for easy and efficient removal of fluoride from contaminated water with good reusability.The current work suggests a simple and effective method to remove fluoride from contaminated water.

Fabrication of Poly(vinylidene fluoride) /Polysulfone Flat Blend Membranes via Thermally Induced Phase Separation Process for Water Treatment

Poly(vinylidene fluoride) /polysulfone(PVDF/PSF) flat blend membrane was prepared via thermally induced phase separation(TIPS) technique.The membrane formation mechanism and membrane structure were investigated and the effects of PSF/PVDF weight ratio on morphology,crystallinity,porosity,and mechanical properties of the membrane were discussed.The relationship between membrane structure and performances,such as pure water flux and the rejection of carbonic black,was also discussed.It was found that solid-liquid(S-L) phase separation occurred for the PVDF/PSF/diluent system.The addition of PSF influences structure and crystallinity of the membrane,which in turn influences mechanical properties and performances of the membrane.The results reveal that it is possible to obtain network structure via S-L phase separation by blending the polymer,which has a partial compatibility with PVDF.

Removal of Fluoride from Water Using Mesoporous MCM-41: An Optimization Approach Using Response Surface Methodology (RSM)

Fluoride above 1.5 mg·L-1 is injurious to health. Removal of fluoride from water using mesoporous MCM-41 as a strong adsorbent material has been attempted. Characterization using transmission electron microscopic study of calcined MCM-41 showed the regular hexagonal array of mesoporous channels with an average size of 20 nm and the surface area (BET study) of 1306.96 m2·g-1. The average pore size of the particles was found to be 14.21 nm. A study on the effect of contact time on the removal of fluoride revealed that more than 85% uptake of fluoride onto MCM-41 was achieved at a contact time of 120 min. From the Langmuir adsorption study, the maximum sorption capacity of fluoride was found to be 63.05 mg/g at 301 K. From the thermodynamic study, the +ΔHo value of 2.29 kJ·mol-1 indicated the endothermic nature of the removal process. Application of Response Surface Model suggested that 77.88% of fluoride removal can be achieved at fluoride concentration of 10 mg·L-1, pH (6.3), and contact time of 120 min.

High Fluoride, Modest Fluorosis: Investigation in Drinking Water Supply in Halaba (SNNPR, Ethiopia)

In Halaba district in Southern Ethiopia fluoride levels from boreholes are high (2.6 to 7.0 mg/l), yet the incidence of fluorosis is modest. Drinking water users living in the vicinity of four drinking water systems that have been in operation for more than 35 years were surveyed. Out of 625 persons 5 percent had severe dental fluorosis and 42 percent had mild forms—which is considerably less than results of other areas with comparable fluoride levels. The incidence was highest in the older age groups. Possible explanations were explored. A likely reason may be the continued large dependence on rain water harvesting ponds for human consumption alongside the use of water from the public borehole systems, but more investigations would be required to confirm this proposition.

Concentration of Fluoride and Arsenic in Bottled Drinking Water in Durango City, Mexico

Arsenic and fluoride are elements known to cause human health problems and it has been documented that both elements are found in high concentrations in the Guadiana Valley aquifer, in the state of Durango, Mexico. Since underground water is the source for potable water bottling companies commercialized in Durango City;such high concentrations reduced the quality of bottled water for human consumption according to NOM-041-SSA1-1993. Legislation establishes a maximum permissible limit (MPL) of 0.7 mg/L for fluoride and 0.025 mg/L for arsenic. In this research the main objective was to evaluate the quality of bottled water expended in Durango City with respect to the well from which water is extracted. Findings showed that the highest fluoride concentration was 5.86 mg/L (8.4 times MPL), with 100% of sampled brands exceeding the MPL (range: 1.09 to 5.86 mg/L). On the other hand, for arsenic, the highest concentration was 0.076 mg/L (threefold), with 38% exceeding the MPL (range: 0.001 to 0.076 ppm). Statistical analysis showed significant differences only for fluoride, according to Fisher LSD (Least Significant Difference) test, with an F value of 14.5 at a p value of 0.0005. According to the comparison between the quantified concentrations in bottled water and groundwater, it was found that groundwater was subjected to treatment;however, although a significant decrease in fluoride and arsenic concentration was observed, the removal processes used were not efficient to meet set standards.

Efficiency of Nanofiltration Membrane TFC-SR3 and SelRo MPF-34 for Partial Elimination of Fluoride and Salinity from Drinking Water

Consumption of safe drinking water is essential to human health. The excess of certain elements in drinking water causes health problem for people consuming these waters. In Senegal, the excessive levels of fluoride and salts found in the groundnut basin cause public health problem such as dental and/or skeletal fluorosis. Thus, the treatment of such waters is essential before consumption to prevent health problems. For a partial removal of fluoride and salinity, we tested the performance of two commercial nanofiltration membranes namely TFC-SR3 and SelRO MPF-34 at laboratory scale. The results showed that TFC-SR3 membrane was very efficient with rejection rates of 83% - 96% for fluoride ions and 89% - 96% for salinity. For SelRo MPF-34 membrane, retention rates of 25% - 52% were obtained for fluoride ions and 24% - 60% for the salinity.

Experimental Investigations on Fluoride Removal from Water Using Nanoalumina-Carbon Nanotubes Blend

Fluoride is the most abundant, highly electronegative and geogenic contaminant in groundwater worldwide. Among the water quality parameters, the fluoride ion is unique in that it is beneficial to health if its concentration in water is within a threshold value (1.0 - 1.5 mg/l) and is detrimental (>2 ppm) if present in excess (WHO, 2006). High fluoride levels in drinking water has become a critical health hazard of this century as it induces intense impact on human health including skeletal and dental fluorosis. The objective of this study was to evaluate the potential of nanoalumina-carbon nanotubes blend as a sorbent for the removal of excess fluoride from water. Batch studies were conducted to assess the influence of various operational parameters viz. pH, temperature, agitation time, adsorbent dosage and presence of interfering ions. From the studies, it was clear that the rate of adsorption was initially rapid and attains equilibrium gradually in about 100 min. The presence of interfering ions such as chlorides and sulphates has very little effect on fluoride removal by nanoalumina-carbon nanotubes blend. Analysis of the equilibrium data fitted the Langmuir and Freundlich isotherms very well. The results of the study appear to be quite promising in the sense that they demonstrate the capability of nanoalumina-carbon nanotubes blend for removing fluorides from drinking water.

Contamination of Water, Dust, Soil, Rock and Urine with Fluoride in Central India

At least 15% of 0.1 million people residing in 117 villages of Tamnar block (Chhattisgarh, central India) are suffering from fluorosis diseases. In this work, the contamination of F- in the environment (i.e. water, soil, rock and urine) of the Tamnar block is described. The concentration variations of F-, Cl-, NO3-, SO42-, Na+, K+, Mg2+, Ca2+, Al, Mn, Fe and Zn in the groundwater are reported. The F- content in the water was ranged from 1.7 - 17 mg/L with mean value of 9.0 ± 3.7 mg/L. Fluoride was enriched up to 3-, 54-, 69- and 244-folds in the urine, soil, dust and rock, respectively. The cluster and factor analysis models were used to apportion sources of F- and other elements in the water.

Adsorption of Fluoride from Water Using Aluminum Coated Sand: Kinetics, Equilibrium, Effect of pH, and Coexisting Ions

An aluminum coated sand (AlCS) was evaluated as a metal oxide adsorbent for adsorption and removal of fluoride from water using a low-cost adsorbent with potential application in continuous flow adsorber systems. Surface characterization of the AlCS sorbent was performed using TEM, SEM/EDX, XRD and BET. The AlCS sorbent contained mostly amorphous aluminum oxides based on adsorbent characterization results. Favorable adsorption of fluoride onto the AlCS sorbent occurred according to the Langmuir and Freundlich adsorption equations, while physical adsorption of fluoride onto the AlCS sorbent was observed based on results from the Dubinin-Radushkevich equation. Fluoride adsorption onto the AlCS sorbent followed pseudo-second order kinetics, while surface charge analysis indicated a pHPZC of 7.1 for the AlCS sorbent. Effective fluoride removal occurred over a broad pH range from 3 to 11 with a maximum fluoride removal observed at pH 4 to 5. The effect of co-existing ions in water resulted in a decrease in fluoride uptake in the presence of bicarbonate, while resulting in an increase in fluoride uptake in the presence of calcium. The AlCS sorbent was a low-cost and sustainable adsorbent for effective adsorption and rapid removal of fluoride from water within an hour.