IRSPAS 2018
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Item Assessment of hardness and selected anion contents of well water in Mahadivulwewa and Puhudivula grama niladari divisions in Madawachchiya divisional secretariat area(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Fernando, T. D.; Mathota-Arachchige, Y. L. N.Mahadivulwewa and Puhudivula grama niladari (GN) divisions of Madawachchiya divisional secretariat area are highly influenced by agricultural practices. These areas have reported the highest number of CKDu patients. People in these GN divisions have colonized as isolated villages. Therefore, in our study we have selected 10 sites in Mahadivulwewa and Puhudivula representing all villages to analyze the current situation of water quality in those areas. The Calcium, Magnesium, Fluoride, Nitrate, Nitrite, Sulphate, alkalinity, hardness conductivity, salinity and TDS levels were measured according to American Public Health Association (APHA) standards. Results were analyzed using IBM SPSS Statistics 20 software. The Calcium level ranged between 17.30 - 101.35 mg/L and Magnesium level ranged between 4 - 102 mg/L. Fluoride (F-), Nitrate (NO3-), Nitrite (NO2-) and Sulphate (SO42-) levels ranged between 0.02 - 4.3 mg/L, 0 - 8 mg/L, 0.1 - 9.3 mg/L and 4 - 98 mg/L respectively. Alkalinity and hardness levels ranged between 20-250 CaCO3 (mg/L) and 59.7 - 608.9 CaCO3 (mg/L) respectively. With respect to Magnesium, Fluoride, hardness and alkalinity, water samples had exceeded SLS recommended levels by 66.7%, 51.7%, 71.2% and 2.6%, respectively. No water sample had exceeded the SLS recommended levels for NO3-, NO2- and SO42-. Even though there is no significant difference (P >0.05) with respect to above parameters between the sites, there was a slightly low conductivity levels in one site (with the highest percentage of CKDu patients) compared to the other sites. According to these results higher percentages of wells in these areas are not suitable for drinking purposes.Item Investigation of fluoride adsorption capacity of characterized graphene oxide based super sand(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Perera, R. T.; Pathirannehe, P. N. S.; Weerasooriya, R.; Kumarasinghe, A. R.; Liyanage, J. A.Sand is conventionally used in water treatment plants to control water turbidity. This research work was aimed for improving its performance using a chemical modification to remove other water contaminants as well. Thus improved substrate was designated as “Super Sand”. Super sand has proven to be a better adsorbent for the removal of fluoride from water. Fluoride is an essential constituent for human health and toxicity of the fluoride depends on the concentration of the fluoride in the drinking water source. The fluoride adsorption capacity of characterized super sand was determined. Graphene Oxide (GO) was synthesized using the modified Hummers method and then GO was coated with purified sand for the generation of super sand. Single GO coated super sand and multiple GO coated super sand were synthesized for the investigation of fluoride adsorption capacity. GO and super sand were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDXAS), Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) analysis and surface titration. Surface titration curve depicted that surface charge of super sand vary with pH value of the medium. Between pH 4 to 7 it has a total positive charge and above pH 7 it has a total negative charge. In order to determine the fluoride adsorption process, isotherm studies were done for both single coated and multiple coated super sand. According to the isotherm studies, single coated super sand has the maximum fluoride adsorption capacity at 2 mg/L fluoride concentration and multiple coated one has maximum fluoride adsorption capacity at 3 mg/L fluoride concentration. Further optimization studies were also performed and finally it was proved that fluoride adsorption by the super sand follows the Langmuir isotherm model. Further, FTIR analysis of super sand and fluoride adsorbed super sand at different pH mediums depicted that adsorption process is a chemisorption process. However, FTIR peak patterns depend on the pH of the medium. Hence, it can be concluded that surface modified super sand is suitable for the fluoride removal from the fluoride contaminated drinking water.Item Defluoridation of drinking water using physically and chemically modified chitosan(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Pathirannehe, P. N. S.; Fernando, T. D.; Rajapakse, C. S. K.Depending on the total intake, fluoride (F-) is known to have both beneficial and adverse effects on humans. As the occurrence of the Chronic Kidney Disease of unknown etiology (CKDu) is thought to be linked with excess levels of F- in drinking water, the search for efficient, readily available, more affordable and eco-friendly adsorbents that have defluoridation potential has intensified in recent years. Therefore, the current study focuses on use of chitosan-derived adsorbents, physically and chemically modified chitosan for the removal of F- from drinking water. Physically modified chitosan; chitosan beads (CB), and chemically modified chitosan; protonated glutaraldehyde cross-linked chitosan beads (GCLCB/H+) and protonated glycerol diglycidyl ether cross-linked chitosan beads (GDCLCB/H+) were prepared, and characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope. Batch experiments were conducted to determine the effect of adsorbent dosage, initial F- concentration, pH and contact time on defluoridation capacity of GCLCB/H+ at 30 ± 20C and the defluoridation capacities of different chitosan derivatives were determined under the optimized conditions (adsorbent dosage = 0.6 g, initial F- content =15 mg/L, contact time = 30 min, pH = 7). Further, the adsorption isotherm studies were conducted to understand the F- sorption process. The results revealed that the defluoridation capacities of CB, GCLCB/H+ and GDCLCB/H+ under optimized conditions at 30 ± 20C were 76.04 mg/kg, 576.98 mg/kg and 655.37 mg/kg, respectively and these values were significantly greater than that of unmodified chitosan flakes (44.20 mg/kg). The results indicate that physical and chemical modification of chitosan have enhanced the F- adsorption capacity of chitosan-derived adsorbents. Further, the results of the isotherm experiments indicated that the adsorption process is well fitted to Langmuir and Freundlich isotherm models. Six water samples among the drinking water samples collected around Kirigollewa Grama Niladhari Division in Medawachchiya, have exceeded the permissible level of F- in drinking water as defined by WHO (1.5 mg/L), but were able to successfully reduce to the permissible range by treatment with GDCLCB/H+. The findings of this study demonstrate that chitosan derived adsorbents are efficient and cost-effective candidates to use in removing F- ions from drinking water.