Browsing by Author "Amarasooriya, A.A.G.D."

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    Development of a Systematic Risk Identification and Assessment Method in Water Safety Plan: A Case Study of Pelmadulla Water Supply Scheme, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2016) Nadeeshani, L.H.T.; Amarasooriya, A.A.G.D.; Weragoda, S.K.
    This study proposes a novel method for risk assessment in Water Safety Plan (WSP). WSP is a management approach proposed by the World Health Organization to ensure the water quality from the source to the consumer. WSP consists of 11 modules that assist to identify and solve water quality issues and possible risks in water source, treatment and supply through an organizational management approach. However it does not provide adequate guidelines for its most critical risk assessment as described in Module 3 - Identify hazards and hazardous events and assess the risks to the water quality. WSP guideline Module 3 proposes a semi quantitative single factor risk assessment. But for a single risk there may be several associated co-risk factors. Therefore this study proposes a systematic risk identification and assessment method by considering co-risks. Furthermore this study evaluates the novel method and old method results. Co-risk factors involved in single risk were identified by using past and current water quality data, consumer opinions and operator opinions through questionnaire surveys and laboratory analysis. Risk assessment was performed with semi-quantitative approach. Results reveal that the new method is capable of identifying and evaluating the risks in a more objective manner and there is a significant difference between then risk ratings obtained through this novel approach and previous methods. Of the 16 hazardous events 10 were identified to be 'high risk' under the previous scheme. The new method has lowered it to 6 high risk hazardous events. The proposed novel method will be more economical in implementation of the WSP as it performs a rigorous assessment of critical hazardous events. Keywords: Water Safety Plan, Hazardous events, Risk assessment
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    Leaching of Aluminium and Its Incorporation into Rice During Cooking under Different Fluoride Concentrations in Water
    (Uva Wellassa University of Sri Lanka, 2012) Amarasooriya, A.A.G.D.
    Majority of the people in Sri Lanka use aluminumcooking utensils for cooking rice and other types of food. Aluminum is toxic to human if injected in excessive concentrations. Leaching of aluminum from cooking utensils has been reported by several investigations.Since fluoride in water has an affinity to make complex ions with aluminum. Fluoride in cooking water can enhance attraction ofaluminum in to the cooking medium and hence to the cooked food. Under the present study naturalaluminum level andleaching of aluminum and its incorporation in to rice during cooking under different fluoride stresseswere studied. Aluminum was determined using a UV Spectrophotometric method. The experiment was done in the laboratory where rice was cooked in a glass beaker with an aluminum plate in it under different fluoride concentrated water. Samples were then digested so that aluminum could be determined by spectrophotometrically. Natural aluminum level of the raw rice (Oryza sativa)was significantly large. It was observed a concentration of0.2038mg/g aluminumin rice. Rice cooked at the present of aluminum plate but without fluoride watershows an addition of 0.0065mg/galuminum to rice. An addition of 0.1367mg/galuminum was noted at a fluoride concentration of 6mg/1 in water which is comparative to highest fluoride levels of Sri Lankan ground water. Total aluminum was found to be high in the rice cooked under normal water as well as in the fluoride richwater. Aluminum in cooked rice increased with theincreasing fluoride concentration in the water. It was found that total aluminumlevel in cooked rice was 0.2135 mg/g when cooked in fluoride free water and it was 0.3438 mg/g at 6 mg/1 fluoride in water. The maximum allowed aluminum intake per normal personis 0.1428 mg/kg body weight per day. Based on the assumption that one person who eat 250 g rice per day, the aluminum intake according to present experiment is greater than 0.1428 mg/kg and hence risky. present study shows that Sri Lankan community in areas of fluoride rich ground water are vulnerable to inject of high aluminum at toxic levels through aluminum cooking utensils alone. The risk can be much higher when substandard aluminum pots that are easily dissolved in cooking medium.
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    Removal of Excessive F-, Mg2+ and Ca2+ in Groundwater by Electrolysis
    (Uva Wellassa University of Sri Lanka, 2018) Jayawardena, N.K.R.N.; Amarasooriya, A.A.G.D.; Weragoda, S.K.
    Groundwater contamination in North Central Province, Sri Lanka by excessive fluoride (F), magnesium (Me) and calcium (Ca2+) causes many negative health effects to the consumers. Though many technologies are available to remove F-, Mg2+ and Ca2+, installation and maintenance cost, power consumption, expertise knowledge, output water quality and the water rejection have become bottle necks on providing the safe water. Electrolysis has proven as a cost effective method. Therefore, in this study, electrolysis was investigated to remove F-, Mg2+ and Ca2+ ions. As an electrolysis reactor, a Polyvinyl Chloride material made rectangular box, which was separated from a clay membrane was utilized by employing platinum and stainless steel electrodes. Electrolysis was performed by varying Coulombs (Ampere x second รท Liters) per Liter (C L-1) for groundwater samples collected from North Central Province. During the electrolysis, contaminants were removed via forming a white colored precipitation in the cathode bath and transportation by coulomb forces towards the anode bath. The total water recovery by the system was 50%. Analytical results showed that significant amount of hardness species (Ca2+ and Mg2+), HCO3- and F- can be removed. The precipitation could be a mixture of CaCO3, MgCO3 and Mg(OH)2 which formed by reacting HCO3- and OH- ions with Ca2+ and Me. Fluoride could be removed via coprecipitation with Magnesium hydroxide. Moreover it was identified that current supplied has a positive effect on hardness species and F removal. The maximum removal percentage was 71.6% for the Mg2+ at 1000 C L-1. The Ca2+ and F- removal observed were up to 94.45% and 39.79% respectively for the 1000 C L-1. There was no significant effect on removal percentages by the initial concentration, but the higher the initial Me2+ and Ca2+ concentrations, the higher the removals of Mg2+, Ca2+ and F. Accordingly, household scale treatment system was designed and proposed.