Defluoridation Of Water Research Articles

In-situ synthesis of calcium/magnesium phosphate system for water de-fluoridation: Clay ceramic materials

Clay ceramic water filters impregnated with silver colloids have been used to purify water in many parts of East Africa disregarding the removal of fluoride, which is a health-threatening ion in water supplies. This paper presents a synthesis of clay ceramic materials containing in-situ generated calcium/magnesium phosphate system as an adsorbent for water de-fluoridation. The materials were prepared in varied ratios of clay (K) to heat-pretreated dolostone (R) (K:R = 0:100, 90∶10, 85∶15, 75∶25 and 100:0), sintered at temperatures between 500 °C and 900 °C, and characterized using XRF, AAS, CHNS–O analyzer and X-ray PDF analysis. The materials improved in de-fluoridation performance with increase in sintering temperature at 500–700 °C, before exhibiting a sharp drop at 800 °C. The adsorption performance of K:R = 75:25 was higher than that of K:R = 0:100, signifying the effect of clay. The adsorption data obeyed Freundlich isotherm model, suggesting multi-layer adsorption. Fluoride uptake follows pseudo-second-order and intra-particle diffusion models, which suggests a chemisorption process involving rate-limiting intra-particle diffusion.

Defluoridation of water by Ce-Ti hybrid oxide nanoparticles

In the present work, Ce-Ti and Ce-Ti/Fe3O4 hybrid oxides were prepared by co-precipitation method and then characterized by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and scanning electron microscope (SEM) techniques. The nano-adsorbents were applied to remove fluoride (with the concentration range of 10–30 mg L−1) from aqueous solution, reaching the adsorption equilibrium within 30–60 minutes. Practically, the fluoride removal onto both nanomaterials was efficient at the neutral pH (pH 5–7) and obeyed the Langmuir adsorption isotherm with the maximum adsorption capacities of 22.78 mg g–1 (Ce-Ti) and 20.28 mg g–1 (Ce-Ti/Fe3O4) at room temperature.

Comparison of Water Defluoridation Using Different Techniques

Fluoride pollution in subsurface water is a significant problem for different nations across the world because of the intake of excessive fluoride caused by the drinking of the contaminated subsurface. Water pollution by flouride can be attributed to the natural and human-made agents. Increased levels of fluoride in drinking water may result in the irretrievable demineralization of bone and tooth tissues, a situation called fluorosis, and other disorders. There has long been a need for fluoride removal from drinking water to make it safe for human use. Among the various fluoride removal methods, adsorption is the method most popularly used due to its cheap cost, ease of utilization, and being a scalable and simple physical technique. According to the findings of this study, the highest concentration of fluoride (0.1–15.0 mg/L) was found in Sweden and the lowest (0.03–1.14 mg/L) in Italy. We collected the values of adsorption capacities and fluoride removal efficiencies of various types of adsorbents from valuable released data accessible in the literature and exhibited tables. There is still a need to find the actual possibility of using biosorbents and adsorbents on a commercial scale and to define the reusability of adsorbents to decrease price and the waste generated from the adsorption method. This article reviews the currently available methods and approaches to fluoride removal of water.

Saw dust-derived activated carbon in different impregnation ratios and its application in de-fluoridation of waste water using IT2FLC and RSM

Saw dust-derived activated carbon in different impregnation ratios and its application in de-fluoridation of waste water using IT2FLC and RSM

Defluoridation of water with a coagulant, Strychnos potatorum L. seed –agglutinin

The aim of the present study is to assess the suitability of Strychnos potatorum L. seed protein for defluoridation of potable water. Protein was isolated from Strychnos potatorum L. seed by using Ammonium sulphate precipitation method and coagulation activity was confirmed. Later the extracted protein was used for defluoridation studies of aqueous fluoride solution and real potable water. The effect of three parameters including pH, time and coagulant dosage of protein on the fluoride removal were studied in fluoride aqueous solution. About 52 potable water samples in and around Kodaikanal were collected from tribal and non-tribal areas and water quality was assessed. The exceeding amount of fluoride among 5 water samples was found when compared with BIS standard for drinking water and subjected to defluoridation process with coagulant protein. Strychnos potatorum L. seed coagulant protein removed about 75% of fluoride from aqueous fluoride solution (2 ppm) by 2 h treatment time, at 6.6 pH with 0.1 g of coagulant dose, treatment. Potable water defluoridation also showed 75% of fluoride reduction with 0.1 g of coagulant dose treatment. Seed characterization was performed using GC–MS and FT-IR, also proteomic studies carried out using MALDI-TOF. The seed coagulant protein showed, horcolin, a lectin type agglutinin protein (15.1 kDa) with 146 amino acid residues. This study suggests, the horcolin agglutinin protein in seeds is capable to remove fluoride effectively from drinking water samples due to the presence of its metal binding sites. • Strychnos potatorum L. seed coagulant protein was introduced for defluoridation. • Effect of pH, time and dosage on fluoride removal of aqueous solution was studied. • Seed coagulant defluorinated maximum 75% of fluoride from water samples. • FT-IR and GC–MS confirmed amide group for defluoridation and antioxidant property. • Coagulant horcolin protein was identified at 15.1 kDa with 146 amino acids.

Enhanced Defluoridation of Water Using Zirconium-Coated Pumice in Fixed-Bed Adsorption Columns.

Millions of people across the globe suffer from health issues related to high fluoride levels in drinking water. The purpose of this study was to test modified pumice as an adsorbent for the purification of fluoride-containing waters. The adsorption of fluoride onto zirconium-coated pumice (Zr–Pu) adsorbent was examined in fixed-bed adsorption columns. The coating of zirconium on the surface of VPum was revealed by X-ray diffractometer (XRD), Inductively coupled plasma-optical emission spectroscopy (ICP-EOS), and X-ray fluorescence (XRF) techniques. The degree of surface modification with the enhanced porosity of Zr–Pu was evident from the recorded scanning electron microscope (SEM) micrographs. The Brunauer-Emmett-Teller (BET) analysis confirmed the enhancement of the specific surface area of VPum after modification. The Fourier transform infrared (FTIR) examinations of VPum and Zr–Pu before and after adsorption did not reveal any significant spectrum changes. The pH drift method showed that VPum and Zr–Pu have positive charges at pHPZC lower than 7.3 and 6.5, respectively. Zr–Pu yielded a higher adsorption capacity of 225 mg/kg (2.05 times the adsorption capacity of VPum: 110 mg/kg), at pH = 2 and volumetric flow rate (QO) of 1.25 mL/min. Breakthrough time increases with decreasing pH and flow rate. The experimental adsorption data was well-matched by the Thomas and Adams-Bohart models with correlation coefficients (R2) of ≥ 0.980 (Zr–Pu) and ≥ 0.897 (VPum), confirming that both models are suitable tools to design fixed-bed column systems using volcanic rock materials. Overall, coating pumice with zirconium improved the defluoridation capacity of pumice; hence, a Zr–Pu-packed fixed-bed can be applied for defluoridation of excess fluoride from groundwater. However, additional investigations on, for instance, the influences of competing ions are advisable to draw explicit conclusions.

Facile hydrothermal fabrication of functionalized multi‐layer graphene oxide encapsulated chitosan beads for enriched fluoride adsorption

AbstractThe present exploration was focused on the fabrication of environmental friendly adsorbent materials using graphene oxide (GO) and chitosan (CS). To modify GO by functionalization with sulphonic acid gives sulfonated GO (SGO), which possess high defluoridation capacity (DC) than GO. To boost the DC, easily separation and make it in an exploitable form of SGO material, SGO was incorporated onto biopolymer CS gives SGO/CS hybrid composite beads and employed for efficient defluoridation of water. The various influencing parameters of adsorption system viz., shaking time, adsorbate pH, initial fluoride concentration, adsorbent dosage, temperature, and interfering anions were optimized to obtain the highest DC. The DC of SGO/CS composite beads were found to be 4950 mg.kg−1 within 30 min for 10 mg/L of preliminary adsorbate solution by 0.1 g dosage. The surface and structural characterization/properties of the prepared SGO/CS composite beads were evaluated by FTIR, TGA, SEM, and XPS investigations. The attained equilibrium data were predicted by isotherms like Fruendlich, Dubinin‐Radushkevich (D‐R), and Langmuir. The acquired equilibrium data of thermodynamic investigations facilitate to predict the nature of fluoride adsorption process onto SGO/CS composite beads. The plausible defluoridation mechanism of SGO/CS composite beads was discussed in detail. The applicability of SGO/CS beads was investigated at field environment with field water sample.

Defluoridation of water using adsorbent derived from the Labeo rohita (rohu) fish scales waste: Optimization, isotherms, kinetics, and thermodynamic study

Fluoride ions have more affinity towards chitosan material. Fish scales waste is chitosan material generated in abundance in fish markets with virtually no value. The present research attempts to convert this waste to useful adsorbent which can remove fluoride from water. A novel adsorbent is thus developed from the Labeo rohita (rohu) fish scales waste giving thermal treatment for removal of fluoride from water using the batch study of adsorption. Taguchi optimization approach with L16 orthogonal array was adopted to optimize the process parameters for achieving the maximum removal of fluoride. Using ANOM, pH 3; initial F− concentration 5 mg.L−1; mixing time 90 min; adsorbent dose 8 g.L−1 and temperature 303 OK were obtained as optimum values providing a maximum fluoride reduction of 93.32%. Adopting ANOVA, the percentage contribution of each process parameter in descending order of sequence is initial F− concentration 72.44%> pH 20.61% > temperature 2.96% > adsorbent dose 2.45% > contact time 1.55%. The fluoride sorption onto fish scales adsorbent was best fitted with the pseudo-second-order kinetic model and follows the Freundlich isotherm (KF = 0.865, 1/n = 0.407) model. Thermodynamic parameters (ΔS = −6.32 J mol−1.K−1, and ΔH = −2.02 kJ mol−1) suggested a spontaneous, exothermic nature of adsorption and indicates a physiosorption mechanism on a heterogeneous material. SEM and FTIR analysis for surface morphology showed the presence of hydroxyl functional groups is responsible for fluoride sorption. In the regeneration studies, the F – exhausted adsorbent was eluted with 0.1 N NaOH and rinsed with distilled water to prepare the adsorbent for the next cycle. The study indicates the removal of fluoride from water onto fish scales adsorbent is quite feasible, cost-effective, recyclable, and better utilization of locally available waste material into useful adsorbent for defluoridation of water.

Capacitive deionization: a promising technology for water defluoridation: a review

Abstract Capacitive deionization (CDI) is among the promising technologies employed for water purification. CDI has been studied for the removal of various ionic species from water including fluoride ion (F−) with promising results. However, there is no comprehensive literature that summarizes the use of CDI for water defluoridation applications. Therefore, this review paper critically analyzes different electrode materials that have been studied for water defluoridation, their electrosorption capacities and F− removal efficiencies. It further discussed the parameters that influence CDI efficiency during defluoridation and point out the issues of F− selectivity when co-existing with other ions in the solution. We can conclude that different electrode materials have shown different abilities in electrosorption of F−. The carbon-based materials possess high surface area and good electrical conductivity which is paramount for ion adsorption but gives lack selectivity for F− removal. Metal oxides and hydroxides have been reported with improved electrosorption capacity and high selectivity to F− due to the ion exchange between the F− and the hydroxyls surface of the metal oxides/hydroxides. Apart from the good performance of these materials for defluoridation, the discovery of actual practical use of the electrode materials for defluoridation for commercial scale is still a need.

Enhanced fluoride removal from water by nanosized cerium oxides impregnated porous polystyrene anion exchanger

Efficient elimination of fluoride from wastewater is an urgent need for ensuring water safety. In the present study, a stable and reusable nanocomposite (NCO@PAE) was synthesized by impregnating nanosized cerium oxides (NCO) inside a porous polystyrene anion exchanger (PAE) host for efficient fluoride removal from wastewater. The newly fabricated NCO@PAE exhibited excellent resistance to acid and alkali environment, allowing it to be utilized in a wide pH range (2–12). Fluoride uptake onto NCO@PAE was a pH-dependent process, which could reach the maximum capacity at pH 3.0. Compared with its host PAE, NCO@PAE showed conspicuous adsorption affinity towards fluoride in the coexistence of other competing anions at high concentrations. Adsorption kinetics confirmed its high efficiency for achieving equilibrium within 120 min. Fixed-bed adsorption runs demonstrated that the effective processing capacity of NCO@PAE for synthetic fluoride-containing wastewater (initial fluoride 2.5 mg/L) was about ~330 BV (bed volume), while only 22 BV for the host PAE. The exhausted NCO@PAE could be effectively revived by a simple in-situ desorption method for long-term cycle operation without conspicuous capacity loss. All the results indicated that NCO@PAE is a reliable and promising adsorbent for water defluoridation.

Impacts of recycled polysulfone on the salt separation performance of thin film poly(piperazine-amide) membranes

The reusability provisions for finding out the feasibility of a polysulfone (PS) membrane structure are considering the type of stimulating system. On the successive non-solvent phase inversion of PS, the Newtonian flow of PS solutions at different stages is well observed from the rheological study. The viscosities of PS solutions decrease with stages. The membranes (Memb.-I-Ps to Memb.-VIII-Ps) are prepared from PS, recycled from successive phase inversion stages. It develops better porosities and higher Molecular weight Cut-off (MWCO) (PEO 200,400KDa)). Poly(piperazine-amide) coating on different recycled stages of PS membranes (Memb.-I-Pip to Memb.-VIII-Pip) shows an MWCO (PEG 400 Da, 1000 Da) property. The wettability property, zeta potential, morphological features of the membranes vary with the number of recycled stages. The salt rejection profiles (NaCl and Na2SO4) increase with the successive stages of recycled PS, and the selectivity (Na2SO4/NaCl) decreases a little. The Marangoni effect can explain the rise in salt separation with the subsequent recycled stages. The study extends to the defluoridation of water and quite promising. The ~15% increase in separation for 10 mg/L fluoride from Memb.-I-Pip to Memb.-VIII-Pip. The maximum separation of fluoride is 84.9% for Memb.-VIII-Pip. The decrease in separation results when the fluoride concentration increases from 10 to 100 mg/L.

Study on the Synthesis and Structural Properties of Zeolite A-MgO Composite for Defluoridation of Water

Zeolite A-MgO composite was synthesized in presence of zeolite A particles, MgCl2 and urea solution under hydrothermal reaction at 150oC for 5 h followed by calcination at 600°C/2 h. XRD and FTIR results showed the crystallization of MgO along with NaA zeolite crystals. Nano-sheet like MgO particles (50-70 nm) were grown onto the surface of NaA zeolite crystals (1 μm). BET surface area and pore size of the sample were found to be 69 m2.g−1 and 3.9 nm, respectively. XPS analysis showed the binding energies of O1s, Si2p, Na1s, Al2p and Mg2p as 531.6, 102.4, 1072.2, 74.2 and 49.9 eV, respectively. The synthesized product (1 g.L−1 dose) showed 72% adsorption of fluoride (7.24 mg.L−1) within 5 min and reached up to 94% for 90 min at pH 6.8. The adsorption capacity of the sample was calculated as 107.64 mg.g−1 from Langmuir isotherm. The sample could be regenerated up to 5th cycle. A tentative mechanism for the adsorption of fluoride from aqueous solution by the synthesized zeolite A-MgO composite was proposed.

A novel alum impregnated CaO/ carbon composite for de-fluoridation of water

Excessive fluoride concentration (>1.5 mg/L) in water adversely affects human teeth and bones. The present study focuses on the development of a fluoride adsorbentvia wet chemical method, by treating activated carbon and CaO (derived from rice straw and egg shell respectively) with alum. The prepared adsorbents were characterized for various physico-chemical parameters and fluoride adsorption test. The optimized composite with highest fluoride adsorption capacity was further subjected to batch adsorption study. The adsorbent followed second order kinetic model with intra-particle diffusion revealing that the adsorption was controlled by pore diffusion along with the other process, i.e. electrostatic interaction between opposite charges. This has been explained by a mechanism which in turn is supported by XPS data. Langmuir isotherm fitted well with experimental data suggesting homogenous and monolayer adsorption of fluoride. The adsorption capacity obtained from Langmuir isotherm model is 48.78 mg/g. Thus the adsorbent is highly effective in removing fluoride from the initial concentration of 10 ppm to less than 0.2 ppm which is safe for drinking purpose.

Optimization studies for water defluoridation with two-stage coagulation processes using new industrial-based chemical coagulants

The fluoride removal capability of a new industrial-based chemical coagulant (Formula A) in one- and two-stage coagulation treatments was investigated in present study. Three main controlling factors, the coagulant concentration, reaction time and the initial pH of Formula A were studied on the fluoride removal accordingly, with the aid of other coagulants: Ecogent F-Loc, potassium ferrate (K2FeO4), and sodium aluminate (NaAlO2). Response surface methodology (RSM) was adopted to analyse the controlling factors on the fluoride removal efficiency (R%) using Box-Behnken designs (BBD). The coagulant concentration of Formula A shows the most significant effect on R% and better fluoride removal capability at an initial pH 12. Nevertheless, the R% has been shown to be independent of reaction time. Response optimisation revealed the highest R% (70.12%) can be achieved at 1000 ppm, 10 min of reaction time and initial pH of 2. Furthermore, K2FeO4 has a better R% in low pH regions of 2 to 4. Additionally, K2FeO4 achieved the highest R% (84%) at 1190 ppm and pH 9 with 8.5 min of reaction time. In a single coagulation stage, the use of Formula A or K2FeO4 are not able to meet Environmental Quality (Industrial Effluent) Regulations 2009 with discharge Standard B as specified by Department of Environment Malaysia, while a two-stage coagulation process can meet Standard A. Specifically, the combined formulation of using Ecogent F-Loc(1)- Formula A(2) and NaAlO2(1)- Formula A(2) were able to achieve treated water with less than 2 ppm fluoride. Moreover, recycling treated water also plays a major role in helping industries meet the strict treatment standards.

Fluoride Polluted Groundwaters in Calabria Region (Southern Italy): Natural Source and Remediation

Excessive ingestion of fluoride through the consumption of F−-rich drinking water could cause adverse effects to human health. For this reason, the WHO has fixed 1.5 mg/L as the maximum F- concentration for drinking water. In this work, a detailed geochemical characterization was performed to define the source of natural pollution of two groundwaters (samples Pc and Bg) coming from deep crystalline aquifers located in the Calabria region (southern Italy) and to define and optimize the most appropriate water treatment strategy. The samples were classified as a F− enriched NaHCO3 type of water. In particular, the F− concentrations observed were 30 mg/L and 8.9 mg/L for the Pc and Bg samples, respectively. Based on the acquired geochemical characterization knowledge, the groundwaters were treated by two thin-film composite NF membranes, namely SPR 10113 and SPR 10114 which have so far not been used for water defluoridation. It was found that the SPR 10114 membrane was able to guarantee water permeates with F− contents lower than the threshold value of 1.5 mg/L for both treated waters, whereas the fluoride content remained above the threshold value when the Pc sample was treated using the SPR 10113 membrane. The obtained permeates were characterized by a low ionic load and were not suitable for long-term consumption as drinking water. However, all of the produced waters did not need any further re-mineralizing processes for agricultural irrigation or other purposes.

Design and synthesis of amine grafted graphene oxide encapsulated chitosan hybrid beads for defluoridation of water

The promising adsorbent like graphene oxide (GO), chitosan (CS) and amine functionalized graphene oxide (AGO) decorated chitosan (CS) namely AGO@CS composite beads was efficiently prepared for defluoridation studies. The prepared AGO@CS composite beads possess enriched defluoridation capacity (DC) of 4650 mgF− kg−1. Batch method was used to optimize the maximum DC of AGO@CS composite beads. The physicochemical properties of AGO@CS composite beads were explored by numerous instrumental techniques viz., FTIR, Raman, XPS, SEM and TGA investigation. The experimental values of AGO@CS composite beads for fluoride removal at various temperature conditions were assessed with adsorption isotherms, kinetic and thermodynamic studies. The possible defluoridation mechanism of AGO@CS beads was mostly proposed that electrostatic attraction. The reusability and field investigation results of AGO@CS beads shows they are regenerable and applicable at field circumstances.

Fabrication of Manganese-Supported Activated Alumina Adsorbent for Defluoridation of Water: A Kinetics and Thermodynamics Study

Fluoride pollution frequently occurs in many underground drinking water sources due to discrepancies in the geological environment. To address this problem, a manganese-supported activated alumina (MnOOH-supported AA) adsorbent was proposed in the present study. The adsorbent was prepared with an impregnation method, then the morphology and microstructure were systematically characterized. Further, the adsorption kinetics and thermodynamics were systematically explored through static experiments to confirm the adsorption mechanism. The results showed that MnOOH was successfully loaded on the activated alumina (AA), and irregular and convex spinous structures were formed on the surface of particles. Compared with the AA, MnOOH-supported AA exhibited a significantly higher defluoridation rate, which has been doubled. The kinetic behavior of fluoride adsorption on MnOOH-supported AA was governed by the quasi-second-order kinetics model with regression coefficients of 0.9862, 0.9978 and 0.9956, respectively. The adsorption rate was mainly ascribed to the intra-particle diffusion. Additionally, the Freundlich isotherm equation fitted the adsorption thermodynamic process reasonably well compared with the Langmuir adsorption model. Specifically, the correlation coefficients were 0.9614, 0.9383 and 0.9852 at 25 °C, 35 °C and 45 °C, respectively. The adsorption–desorption isotherm plot was similar to the Type V isotherm. The whole fluoride adsorption was a spontaneous endothermic reaction, and controlled by chemical adsorption. These results demonstrated that MnOOH-supported AA as an alternative to the conventional AA showed promising potential for defluoridation in drinking water treatment.

Defluoridation of drinking water using a ceramic filter decorated with iron oxide‐biochar composites

AbstractWhile effective defluoridation methods have been developed, most of them are expensive and difficult to apply at a household level. One safe, low‐cost, decentralized water treatment method which is attracting research attention is the use of ceramic filters (CFs). Few studies have explored the use of biochar composites in CFs for defluoridation of water, with the bulk of them being based on batch and column experiments. The aim of this work was to develop, and evaluate a laboratory‐scale, low‐cost CF using clay, sawdust, and iron oxide‐biochar (FBC) for fluoride removal in synthetic and real water samples. Three CFs were fabricated with varying FBC content (0%, 5%, and 10%). Water absorption, apparent porosity, and flow rate decreased with decreasing FBC content, while the impact strength increased with decreasing FBC content. The CFs reduced the fluoride concentration of both the ground water, and synthetic water to below the WHO recommended limit (1.5 mg/L). While further studies are required to optimize the CF, the results demonstrate that a CF decorated with FBC composites is effective for defluoridation of drinking water.

Synthesis of hydrous CeO2 polypyrrole nanocomposite as a rapid and efficient adsorbent for defluoridation of drinking water

Contamination of water by fluoride ions is one of the major threats to human life and thus must be removed from drinking water. A novel CeO2 polypyrrole nanocomposite (HCeO2@PPy) was fabricated by co-precipitation of CeO2 nanoparticles followed by in situ chemical oxidative polymerization. The as-synthesised adsorbent was characterized using a variety of physico-chemical techniques which included Fourier Transform Infrared Spectroscopy (FTIR), X-Ray diffraction (XRD), Braunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscopy/Energy Dispersive (FE-SEM/EDS), High Resolution-Transmission Electron Microscopy (HR-TEM), X-ray Photoelectron Spectroscopy (XPS) and point-of-zero charge (pzc) determination. The HCeO2@PPy nanocomposite adsorbent was applied for the removal of F− ions from aqueous solution. Application of the adsorption modelling, revealed that the Langmuir adsorption isotherm model best described the process with a maximum adsorption capacity of 70.92 mg g−1, at an optimum pH of 6.0 ± 0.2, 0.03 g adsorbent dose and 25 °C. Rapid kinetic studies revealed that the pseudo-second-order model gives a better description of the adsorption process. Thermodynamic data showed that the adsorption process was physical, spontaneous and feasible. The behaviour of the amino functional groups within HCeO2@PPy moiety and the nanometal oxide surface hydroxides at different pHs along with the pHpzc, FTIR and XPS spectra analyses were used to explain the mechanism of adsorption. The mechanism was conceived to be anionic exchange of hydroxyl group with the F− ions and electrostatic attractions of protonated hydroxyl on the surface of the adsorbent as well as the nitrogen atoms of amino groups from the polypyrrole (PPy) moiety with F− ions. The determined thermodynamic parameters, enthalpy change (ΔH° = −26.33 kJmol−1) and Gibbs free energy change (ΔG° = −19.074 to −10.028 kJ mol−1) indicated the exothermic and spontaneous nature of the sorption process. Further evaluation on the as-prepared adsorbent exposed a moderately selective material which exhibited excellent removal ability of F− ions from ground water at its natural pH to below WHO stipulated levels with an adsorption-desorption efficiency of up to three cycles. Therefore, hydrous CeO2 polypyrrole nanocomposite has revealed great potential for water defluoridation.

Isolation of Fluoride Resistant Microorganisms from Fluoride Contaminated Ground Water Samples of Nalgonda District and their role in Bioremediation

Consuming of water contaminated with high fluoride concentration for a very long time causes health problems such as, dental and skeletal fluorosis. Hence, defluoridation of water is essentially required before consumption, when water is contaminated with high fluoride concentration. In this present study, research was focussed on to isolate bacteria which are showing fluoride resistantance from samples of ground water from high fluoride affected regions of Nalgonda. After analysis of 10 samples from different areas of Nalgonda district, two samples of ground water from Narketpally and Nampally showed the high fluoride concentrations of 9.18 ppm and 7.55 ppm respectively. Hence, in the present study, Narketpally ground water sample with highest ppm was considered to isolate fluoride resistant bacteria. A total of eight fluoride resistant organisms were purified from this sample with varying fluoride resistance on Luria Bertani agar with varying fluoride concentraion from 25mg/L to 600mg/L at pH 7. Among the eight strains isolated, three strains MB1, F and G were showing high fluoride resistance (up to 500mg/L), which were further explored for their role in bioremediation of fluoride. In batch mode study, MB1 strain showed high fluoride degradation of 68%, whereas, F and G strains showed 57% and 44%fluoride removal, respectively, when fluoride concentration was present at 20 mgL-1 at 30 °C temperature and pH 7, with dextrose (10 g) utilised as source of carbon per 100 mL media after incubation of 8 days. Results indicate that, MB1 possibly a potential fluoride resistant bacterium with high fluoride bioremediation capacity.