iPURSE 2015

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https://ir.lib.pdn.ac.lk/handle/20.500.14444/41

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Browsing iPURSE 2015 by Subject "Drinking water"

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    Fluoride uptake by native and modified cattle bones from aqueous medium by batch adsorption
    (University of Peradeniya, Sri Lanka, 2015-11-06) Gunathilake, B.A.P.T.; Iqbal, M.C.M.; Sumanasinghe, V.A.
    Fluoride is found in excess compared to the WHO recommended levels in drinking water in the Kandy district. Health hazards such as dental fluorosis, skeletal fluorosis, crippling fluorosis and metabolic defects in lipids, proteins and vitamins are caused due to excess Fin drinking water. Among several defluoridation techniques, adsorption is the most effective and common method. The objective of this study was to investigate the effectiveness of the natural, economically feasible and eco-friendly materials such as plant leaves and cattle bones for removing fluoride ion from drinking water using batch adsorption method. Bio-adsorbent materials were collected and rinsed initially with tap water, and then with deionized water. Cleaned materials were air dried for 48 h and oven dried at for 48 h. Dried materials were sieved to obtain particle size between 250 – 350 μm. Batch adsorption experiments were conducted. A mass of 0.2 g of different adsorbents was added in 50 mL of 3 mg fluoride solution and shaken at 80 rpm in orbital shaker for 3 h. Thereafter, suspension was filtered and final Fconcentration was determined by fluoride ion-selective electrode. Chemical and physical modifications such as base treatment and bone char preparation were done to enhance the adsorption efficacy. Native bones were heated at 500oC for 3 h in muffle furnace to prepare bone char (BC). Effect of contact time and dosage were determined for chemical modification and effect of pH, kinetic studies, isotherm studies, desorption and adsorbent characterization for BC were carried out. adsorption on BC was maximum between pH 4-7 and equilibrium time for BC was 12 h. Pseudo second order kinetic model and Langmuir isotherm model described adsorption of on BC. The highest desorption was given with 0.1 M NaOH. BC enhances the efficacy of defluoridation from aqueous medium and is a cost effective and eco-friendly biosorbent.
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    Interaction of ferrous ions and free chlorine on microbiological quality of drinking water
    (University of Peradeniya, Sri Lanka, 2015-11-06) Munasinghe, T.S.; Abayasekara, C.L.; Chandrajith, R.; Jayawardana, A.
    University of Peradeniya has a nearly 60 year’s old water distribution network that consists mainly iron pipelines, most of which are now corroded to a large extent, adding iron rust to water. The aim of this study was therefore to investigate the possible consumption of free chlorine that added in to water for disinfection by iron dissolved from pipes. If free chlorine is reduced due to iron, the available amount of free chlorine would not be sufficient for the disinfection of microorganisms in water. A laboratory simulated study was carried out to investigate the possible reaction between ferrous ion and free chlorine in water using a series of and free chlorine mixtures. The effect of the reaction on the inhibition of microorganisms were also determined by spiking Serratia spp. (a total coliform) and Escherichia coli (a fecal coliform) into known mixtures of and free chlorine. The and free chlorine contents were measured spectrophotometerically while viable microbial count was assessed using membrane filtration technique that followed a confirmation tests. Furthermore free chlorine and microbiological quality were determined periodically using 27 water samples that were collected from various points of the University network. The results of this study indicated a rapid reaction between and free chlorine. The rate of free chlorine reduction was directly proportional to the amount of in water. Although inhibition of Serratia spp. and E. coli was observed due to free chlorine in water, the effect reduced drastically with increasing in water. Serratia sp. decreased gradually with the ascending chlorine levels at levels of 0.2 and 1.0 mg/L. Total inhibition of Serratia sp. were observed at 2 and 3 mg/L of while E. coli was inhibited at levels of 1.0, 2.0 and 3.0 mg/L. The content in the water distribution network of University of Peradeniya were ranged from <0.01 mg/L to 0.64 mg/L (desired value is <0.3 mg/L), while the desired free chlorine level (0.2 mg/L) was observed only at two locations (Faculty of Veterinary Science and Meewathura treatment plant). Total coliforms were detected in samples collected from Upper Hanthana, Marcus Fernando Hall, University Temple, Science Faculty, Mars Hall and Medical Faculty, while fecal coliforms were detected only in a sample from Marcus Fernando Hall. The results of microbiological test showed that water distributed from the Kandy Municipal Council and Meewathura plants are suitable for drinking, but water distributed from the Upper Hanthana plant was not suitable for human consumption according to the World Health Organization (WHO) Standards (0/CFU per 100 ml for both total and fecal coliforms) and Sri Lankan Standards (3/CFU per 100 ml for total coliforms and 0/CFU per 100 ml for fecal coliforms). The possible reason behind the unsuitable microbiological quality of water may be related to the reaction between and free chlorine in water. It was also noted that, a high level of in water was inhibitory to microorganisms in water and remove bacteria by formation of clumps.