Lab scale study on electrocoagulation defluoridation process optimization along with aluminium leaching in the process and comparison with full scale plant operation

2011 ◽  
Vol 63 (12) ◽  
pp. 2788-2795 ◽  
Author(s):  
Poonam Gwala ◽  
Subhash Andey ◽  
Vasant Mhaisalkar ◽  
Pawan Labhasetwar ◽  
Sarika Pimpalkar ◽  
...  
Keyword(s):  
Drinking Water ◽  
Process Optimization ◽  
Current Density ◽  
Fluoride Concentration ◽  
Full Scale ◽  
Experimental Results ◽  
Fluoride Removal ◽  
Electrode Polarization ◽  
Operational Conditions ◽  
Aluminium Leaching

An excess or lack of fluoride in drinking water is harmful to human health. Desirable and permissible standards of fluoride in drinking water are 1.0 and 1.5 mg/L, respectively, as per Indian drinking water quality standards i.e., BIS 10500, 1991. In this paper, the performance of an electro-coagulation defluoridation batch process with aluminium electrodes was investigated. Different operational conditions such as fluoride concentration in water, pH and current density were varied and performance of the process was examined. Influence of operational conditions on (i) electrode polarization phenomena, (ii) pH evolution during electrolysis and (iii) the amount of aluminium released (coagulant) was investigated. Removal by electrodes is primarily responsible for the high defluoridation efficiency and the adsorption by hydroxide aluminium floc provides secondary effect. Experimental data obtained at optimum conditions that favored simultaneous mixing and flotation confirmed that concentrations lower than 1 mg/L could be achieved when initial concentrations were between 2 and 20 mg/L. pH value was found to be an important parameter that affected fluoride removal significantly. The optimal initial pH range is between 6 and 7 at which effective defluoridation and removal efficiencies over 98% were achieved. Furthermore, experimental results prominently displayed that an increase in current density substantially reduces the treatment duration, but with increased residual aluminium level. The paper focuses on pilot scale defluoridation process optimization along with aluminium leaching and experimental results were compared with a full-scale plant having capacity of 600 liter per batch.

Fluoride removal from drinking water in Senegal: laboratory and pilot experimentation on bone char-based treatment

2011 ◽  
Vol 1 (4) ◽  
pp. 213-223 ◽  
Author(s):  
Sabrina Sorlini ◽  
Daniela Palazzini ◽  
Carlo Collivignarelli
Keyword(s):  
Drinking Water ◽  
Dental Fluorosis ◽  
Low Cost ◽  
Fluoride Concentration ◽  
Pilot Scale ◽  
Appropriate Technology ◽  
World Health ◽  
Fluoride Removal ◽  
Process Conditions ◽  
Bone Char

In Senegal there are four regions where fluoride concentration in drinking water exceeds the World Health Organization guide value of 1.5 mg/L. This generates permanent damages to the teeth (dental fluorosis) and to the skeleton (skeletal fluorosis). A safe, efficient, simple and low-cost effective defluoridation technique is not available yet and needs to be developed in order to prevent the occurrence of fluorosis. This experimental research was carried out in order to define an appropriate technology for fluoride removal from groundwater in Senegal. Batch tests and filtration tests at laboratory and pilot scale were carried out using animal bone char as adsorbent material for fluoride removal. Possible influencing parameters, such as specific ions in Senegalese drinking water, were investigated and the best process conditions were defined for the application in Senegal. The results attest to the efficacy of bone char in removing fluoride from Senegalese water: at pilot scale the mean specific adsorption was 2.7 mg F−/g of bone char, corresponding to a total treated volume of 4,000 L and a filter life of nearly three months.

Preparation and Characterization of Biogenic Chitosan-Hydroxyapatite Composite: Application in Defluoridation

MRS Advances ◽  
2018 ◽  
Vol 3 (36) ◽  
pp. 2089-2098 ◽  
Author(s):  
Agatha W. Wagutu ◽  
Revocatus L. Machunda ◽  
Yusufu Abeid Chande Jande
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Fluoride Concentration ◽  
Health Concern ◽  
Coliform Bacteria ◽  
Fluoride Removal ◽  
Biomass Waste ◽  
Batch Mode ◽  
Treated Water ◽  
Hydroxyapatite Composite

ABSTRACTIn Northern Tanzania, high levels of fluoride in community drinking water supply is recognized as one of the major public health concern, the problem is further ameliorated by presence Escherichia coli and fecal coliform bacteria in surface water and shallow wells. Efforts to decontaminate the water involve mostly the use of low efficient bone char for fluoride removal without disinfecting the pathogens. To address this problem, a robust adsorbent which is capable of removing fluoride and microbes simultaneously with minimal diverse impact on the treated water is necessary. Here we highlight development of composite material developed from recycling of crustacean biomass waste from sea food industry. Chitosan polymer, isolated from prawns shell was composited with crab shell derived brushite (CaHPO4.2H2O) to form chitosan-hydroxyapatite composite. XRD and FT-IR analysis confirmed transformation of brushite phases into hydroxyapatite and formation hybrid composite. Fluoride adsorption tests were performed in batch mode to evaluate effectiveness. Defluoridation capacity of up to 6.4 mg/g in field water containing fluoride concentration of 5-70 mg/L was achieved. The best performance was observed with fluoride concentration of 10 mg/L and below. Apart from fluoride removal, the composite also reduced color tint and microbes from surface water samples. The pH of the treated water in most samples remained around 6.5-8.5, which is acceptable for drinking water.

Assessing effluent fluoride concentrations following physicochemical wastewater treatment

1992 ◽  
Vol 19 (4) ◽  
pp. 649-659 ◽  
Author(s):  
R. Gehr ◽  
R. Leduc
Keyword(s):  
Drinking Water ◽  
Wastewater Treatment ◽  
Fluoride Concentration ◽  
Treatment Plant ◽  
Full Scale ◽  
Untreated Wastewater ◽  
Balance Analysis ◽  
Full Scale Tests ◽  
St Lawrence River ◽  
Raw Wastewater

The anticipated fluoride concentrations in untreated wastewater, as well as their removal during physicochemical treatment, were determined in order to assess potential risks to the aquatic ecosystem of the St. Lawrence River due to proposed fluoridation of Montreal's drinking water. Monitoring of the raw wastewater yielded average daily fluoride concentrations of 0.22–0.58 mg/L, but discrete sample concentrations ranged from 0.20 to 1.11 mg/L. This indicates that significant massive point discharges occur in the Montreal Urban Community (MUC) sewer system. Jar tests suggest that no precipitation of fluoride would occur following ferric chloride and polyelectrolyte addition at doses similar to those used on the full-scale wastewater treatment plant. This is confirmed by thermodynamic analysis of the solubility of various fluoride species. Full-scale tests, conducted by applying a continuous fluoride dose to the plant influent, confirmed that no removal would result from the treatment process. However, the plant did dampen the shock loads of fluoride from industrial sources. The predicted average raw wastewater fluoride concentration, including ground water and unidentified industrial discharges, was calculated to be 0.83 mg/L. Unidentified sources contribute 132 kg/d (~ 40% of the total). The average fluoride flux in the St. Lawrence River, as a result of fluoridation of the drinking water, would increase by 1.2%. Key words: fluoridation, physicochemical wastewater treatment, St. Lawrence River, mass balance analysis.

scholarly journals Adsorption Efficiency of Cement Impregnated Magnesium Oxide on the Removal of Fluoride

2020 ◽  
Vol 5 (2) ◽  
pp. 109-117
Author(s):  
Iohborlang M. Umlong ◽  
Bodhaditya Das ◽  
Rashmi Rekha Devi
Keyword(s):  
Drinking Water ◽  
Magnesium Oxide ◽  
Fluoride Concentration ◽  
Sorption Process ◽  
Fluoride Removal ◽  
Cement Slurry ◽  
Freundlich Isotherms ◽  
Removal Capacity ◽  
Complex Process ◽  
Pseudo Second Order

Presence of fluoride in drinking water above the prescribed limit may lead to a severe health complication. We present in this paper the fluoride removal capacity of cement impregnated MgO (MgO-cement) from drinking water. MgO-cement was prepared by adding magnesium oxide (MgO) into the cement slurry solution in the ratio of 1:10. Batch experiments were performed as a function of adsorbent dose, contact time, effect of pH and effect of co-ions. The percentage removal decreases with increasing initial fluoride concentration. Co-ions effect revealed that hydroxide ion was found to interfere more with fluoride removal followed by bicarbonate and least effect with sulphate. Reaction mechanism follows Freundlich isotherms. From the kinetic study we observed that uptake of fluoride ion is fast in the first sixty minutes and equilibrium time found to be independent of the initial fluoride concentration. Adsorption kinetics followed the pseudo second order model showing that the sorption of fluoride is a complex process. Surface as well as intraparticle diffusion contribute in the sorption process. No leaching of magnesium in the treated water was detected.

scholarly journals Defluoridation of drinking water by modified natural zeolite with Cationic surfactant, in case of Ziway town, Ethiopia

2021 ◽  
Author(s):  
Dessalegn Geleta Ebsa ◽  
Adisu Befekadu Kebede
Keyword(s):  
Drinking Water ◽  
Cationic Surfactant ◽  
Natural Zeolite ◽  
Fluoride Concentration ◽  
Aggregate Size ◽  
Effect Of Temperature ◽  
Fluoride Removal ◽  
Ammonium Bromide ◽  
Modified Zeolite ◽  
Peasant Farmers

Abstract. In Ethiopia (Ziway town) an excess fluoride (≥ 1.5 mg/L) consumption in drinking water (ground water and Lake Ziway) sources causes a health problem on the communities. The surrounding of inhabitant's peasant farmers of drinking water sources was extremely relying on this polluted fluoride concentration of water. This investigation was focused on defluoridation of drinking water by natural zeolite modified with a cationic surfactant in a batch system and Hexadecy Trimethyl Ammonium Bromide were used for zeolite modification. The Batch experiments also conducted to test for preferential removal of fluoride from water by surfactant-modified zeolite. The zeolite treatments had an aggregate size of 1.4 to 2.4 mm. The cationic surfactant-modified zeolite, and raw zeolite were used in all experiments. The removal efficiency of the treatment was influence by pH of solution (5.5 ± 0.2–8.5 ± 0.2), initial concentration of fluoride (1–10 mg/L), dose of surfactant-modified zeolite (2.5–18 g/L), contact time (30–180 Minute), and effect of temperature was investigated. The study investigated that, at the constant Blank of 10 mg/L, 5 g/L of Hexadecy Trimethyl Ammonium Bromide dosage noted the highest fluoride removal potential at the end of the 3hours runtime: Na-LSX (88.4 %), Na-LTA (64.6 %) and ZR (79.8 %). Incompatible to this reflection, the model waters with pH maintained at 5.5 ± 0.2 and 6.5 ± 0.2 verified rapid fluoride removal (89.7 % and 72.3 % respectively) within the first 60 minutes of runtime.

scholarly journals Enhanced fluoride removal from drinking water in wide pH range using La/Fe/Al oxides loaded rice straw biochar

2021 ◽  
Author(s):  
Nan Zhou ◽  
Xiangxin Guo ◽  
Changqing Ye ◽  
Ling Yan ◽  
Weishi Gu ◽  
...  
Keyword(s):  
Drinking Water ◽  
Rice Straw ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Batch Adsorption ◽  
Solution Ph ◽  
Adsorption Sites ◽  
Wide Ph Range ◽  
Rice Straw Biochar ◽  
Ph Range

Abstract A novel and highly efficient adsorbent was prepared by loading La/Fe/Al oxides onto rice straw biochar (RSBC) and was tested for the ability to remove fluoride from drinking water. Characterized by SEM, XRD, Zetapotential and FTIR, it was found that the ternary metal oxides were successfully loaded on the surface of biochar in amorphous form, resulting in the formation of hydroxyl active adsorption sites and positive charges, which played a synergistic role in fluoride removal. Through batch adsorption tests, key factors including contact time, initial fluoride concentration, initial pH and co-existing anions effects were investigated. Results showed that the tri-metallic modified biochar (La/Fe/Al-RSBC) had excellent fluoride removal performance with an adsorption capacity of 111.11 mg/g. Solution pH had little impacts on the removal of fluoride, the adsorbent retained excellent fluoride removal capacity in a wide pH range of 3.0–11.0. The co-existing anions had almost no effect on the fluoride removal by La/Fe/Al-RSBC. In addition, La/Fe/Al-RSBC could be regenerated and reused. Electrostatic adsorption and ion exchange were responsible for this adsorption behavior. These findings suggested the broad application prospect of a prepared biochar adsorbent based on rare earth and aluminum impregnation for the fluoride removal from drinking water.

Adsorption of Fluoride on Limestone-Derived Apatite

2012 ◽  
pp. 128-138
Author(s):  
Cyprian Murutu ◽  
Maurice S. Onyango ◽  
Aoyi Ochieng ◽  
Fred Otieno
Keyword(s):  
Drinking Water ◽  
Adsorption Capacity ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity ◽  
Dental And Skeletal Fluorosis ◽  
Equilibrium Data ◽  
Pseudo Second Order ◽  
Permissible Levels ◽  
Ph Range

Fluoride in drinking water above permissible levels is responsible for human dental and skeletal fluorosis. Adsorptive based defluoridation is the most popular technique with several end-user applications. Consequently, this paper describes the fluoride removal potential of a novel sorbent, limestone-derived apatite from drinking water. The adsorbent was prepared by calcining limestone followed by reacting with orthophosphoric acid. Batch sorption studies were performed as a function of contact time, pH, initial fluoride concentration, temperature and adsorbent dose. Sorption of fluoride was found to be pH dependent with a maximum occurring in the pH range of 5-9. The authors also observed that the material had a buffering effect on the same pH range. Meanwhile, the adsorption capacity was found to increase with temperature, depicting the endothermic nature of the adsorption process and decreases with adsorbent mass. The equilibrium data was well described by the conventional Langmuir isotherm, from which isotherm the maximum adsorption capacity was determined as 22.2 mg/g. From the kinetic perspective, the fluoride adsorptive reaction followed the pseudo-second order mechanism.

scholarly journals Effects of Calcination Temperature of Naturally Occurring Absorbents on Drinking Water Defluoridation

2020 ◽  
Vol 39 (2) ◽  
pp. 165-176
Author(s):  
Brenda Mndolwa ◽  
Felix Mtalo
Keyword(s):  
Drinking Water ◽  
Calcination Temperature ◽  
Removal Efficiency ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Treated Water ◽  
Calcination Temperatures ◽  
Natural Adsorbents ◽  
Different Temperatures ◽  
Water Quality Deterioration

Currently, in Tanzania, fluoride removal from drinking water is treated mostly using the bone char method. The method has poor acceptability in some religious communities and also causes water quality deterioration in taste and odour if the bones are not properly prepared. The use of local natural adsorbents as an alternative is feasible with limitations of high levels of other impurities in treated water. Locally available gypsum, magnesite and bauxite were converted to adsorbents through calcination. The study was conducted to determine the removal efficiency, best calcination temperature and composite ratio of the three adsorbents for the removal of fluoride from natural drinking water with fluoride concentration as high as 16.7 mg/L. The adsorbent materials were calcined at different temperatures ranging between 3500C and 6000C. Batch experiments were performed and samples were collected at different contact time intervals of 2 minutes to 60 minutes, and residual fluoride was determined. Bauxite had the highest fluoride removal efficiency compared to gypsum and magnesite. The best calcination temperatures were 3500C, 4000C, 6000C for gypsum, bauxite and magnesite, respectively. The best calcination temperatures were used to prepare composites at different ratios of 1:2:3, 2:3:1 and 3:2:1, bauxite: gypsum: magnesite respectively. All the ratios gave low sulphate and iron as impurities within the recommended standards. The composites lowered fluoride concentration level to 1.53 mg/L, 2.07 mg/L, 2.60 mg/L for 1:2:3, 2:3:1, 3:2:1 ratios, respectively. In conclusion the study reveals that, it is possible for composites made of adsorbent calcinated at different optimum temperatures to give good results in fluoride removal from drinking water, as well as standard pH, iron and sulphate values in treated water.

scholarly journals Defluoridation of South Tunisian Brackish Water by Alum Coagulation/Flocculation: A Preliminary Work

2017 ◽  
Vol 5 (3) ◽  
pp. 727-740
Author(s):  
Khaoula Missaoui ◽  
Wided Bouguerra ◽  
Chiraz Hannachi
Keyword(s):  
Brackish Water ◽  
Fluoride Concentration ◽  
Settling Time ◽  
Experimental Results ◽  
Fluoride Removal ◽  
Operating Parameters ◽  
High Fluoride Concentration ◽  
Initial Ph ◽  
High Fluoride ◽  
Alum Coagulation

Fluoride removal from aqueous solution was investigated using the chemical coagulation-flocculation by alum in reason of the efficiency and the simplicity of the process. Preliminary experiments were carried out to study the effect of some operating parameters such as: pH, initial fluoride concentration, coagulant dose, adjuvant coagulation dose, flocculent dose and settling time. Obtained experimental results showed that the treatment of fluoride by alum coagulation causes acidification of the solution. The effect of the initial pH solution on fluoride removal is negligible. Experimental results proved that coagulation process is effective in waters with low or medium levels of fluoride. Defluoridation rate was seen to increase with increasing coagulant and adjuvant coagulation doses. Optimal flocculent dose and optimal settling time were found 4.2 mg L-1 of FABI and 60 min respectively. Subsequently, experimental design methodology using two-level full factorial design was applied to optimize the defluoridation by coagulation-flocculation. Therefore, four operating parameters which are supposed to affect the removal efficiency were chosen: initial fluoride concentration, coagulant dose, coagulation adjuvant dose and settling time. From the statistical analysis, it is inferred that the four studied parameters have an influence on the fluoride removal. In fact, initial fluoride concentration has a positive effect unlike coagulant dose, coagulation adjuvant dose and settling time. Experiment tests were performed to evaluate the efficiency of coagulation-flocculation process for south Tunisian brackish water with high fluoride concentration. The obtained results showed that fluoride removal reached 59%.

scholarly journals Arsenic and Fluoride in Groundwater, Prevalence and Alternative Removal Approach

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1191
Author(s):  
Adriana Robledo-Peralta ◽  
Miriam López-Guzmán ◽  
Corazón G. Morales-Amaya ◽  
Liliana Reynoso-Cuevas
Keyword(s):  
Drinking Water ◽  
Arsenic Removal ◽  
Fluoride Removal ◽  
Well Water ◽  
Initial Concentration ◽  
Operational Conditions ◽  
Groundwater Arsenic ◽  
Electrocoagulation Process ◽  
Alternative Approaches ◽  
Interfering Ions

Contamination of drinking water by arsenic and fluoride is a global problem, as more than 300 million people in more than 100 countries have been affected by their presence. These elements are considered the most serious contaminants in drinking water and their removal is a worldwide concern. Therefore, the evaluation of three alternative approaches—electrocoagulation, adsorption by biomaterials, and adsorption by metal oxide magnetic nanoparticles (MNPs)—was performed for arsenic and fluoride removal from groundwater. Arsenic removal from synthetic and groundwater (well water) was accomplished with the three processes; meanwhile, fluoride removal from groundwater was only reported by two methods. The results indicate that an electrocoagulation process is a good option for As (>97%) and F (>90%) removal in co-occurrence; however, the operational conditions for the removal of both pollutants must be driven by those used for fluoride removal. As (80–83%) and F (>90%) removal with the biomaterials was also successful, even when the application objective was fluoride removal. Finally, MNPs (Co and Mn) were designed and applied only for arsenic removal and reached >95%. Factors such as the pH, the presence of interfering ions, and the initial concentration of the contaminants are decisive in the treatment process’s efficiency.

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