Browsing by Author "Udagedara, D. T."

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    Development of Electrochemical Method to Remove Nitrogenous Compounds from Prawn Industry Wastewater
    (Uva Wellassa University of Sri Lanka, 2018) Kirujika, K.; Kreshaanth, S.; Gunathilake, C. A.; Udagedara, D. T.; Manipura, A.
    The prawn-farm industry is one of the fastest growing export-oriented industries in Sri Lanka. Wastewater originating from prawn-farms contains an excessive amount of nutrients that becomes a serious environmental issue. Currently, there is no proper wastewater treatment method to remove nitrogenous compounds in Sri Lanka. Thus, the study aimed to develop an electrochemical method to remove nitrogenous compounds from simulated prawn-farm wastewater. Further, this method investigated the effect of control factors such as pH, retention time, current, and surface area of the electrodes using Taguchi method which identifies proper control factors to obtain the optimum results in the removal of nitrogenous compounds by using carbon and aluminum electrodes with KCl salt bridge. Results indicate that with carbon electrodes the maximum (50%) removal efficiency was obtained in 16 hours constant retention time and changing pH, DC, and surface area, respectively, about 4, 350 mA at 22.4 V, and 10 cm2. Our results are comparable to the results obtained with Taguchi method where the optimum level was obtained under following conditions where pH = 4, DC = 450 mA at 22.4 V, retention time = 16 hours, and surface area = 40 cm2. In aluminum electrodes the maximum (54%) removal efficiency was obtained by changing retention time, pH, DC, and surface area with controlling parameters of 4 hours, 2, 450 mA at 22.4 V, and 10 cm2, respectively. Results are comparable to results obtained with Taguchi method where optimum level have obtained under following conditions where pH = 2, DC = 250 mA at 6.8 V, retention time = 4 hours, and surface area = 40 cm2. Therefore, the results concluded that aluminum electrodes are better than carbon electrodes to remove nitrogenous compounds even though carbon electrodes can be used due to its low cost, simplicity, and easily renewable surface. The electrochemical method could be a potential method to remove nitrogenous compounds due to its high efficiency, low cost and ease in handling.
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    Investigation on the Manganese Phase Diagram when Manganese is Reacting with Calcium Hypochlorite
    (Uva Wellassa University of Sri Lanka, 2019-02) Abeysinghe, S. A.; Weragoda, S. K.; Weerasekara, W.B.M.L.I.; Udagedara, D. T.
    Oxidation Reduction behavior of different substances highly contributes to the condition of water and phase diagram express the relationship between Eh and pH of a particular substance. When Manganese is in water, it can exist either as suspension matter or as dissolved matter and exact speciation can be determined by investigating the Manganese phase diagram. The objectives of this study were to investigate a suitable method to reduce excess Manganese from water by flocculation and filtration process and identify the different species of Manganese from phase diagram which can be removed from water as insoluble form. Excess concentration of Manganese was reduced by oxidizing to an insoluble form using Calcium hypochlorite and resulting insoluble form was removed by flocculation and filtration. Behavior of the Manganese species fluctuates with different pH and Eh values. The pH values of the samples were measured directly by pH meter and Eh values were determined by both calculated value from Nernst equation and measured value as oxidation reduction potential. After 30 minutes of time residual Chlorine values of all the trials were zero. Manganese rich water was synthetically prepared by adding MnSO4 in to raw water sample collected from Maguru Oya, Wariyapola. Manganese was removed as a brown color deposition which was confirmed as Mn3O4 (Hausmannite) by Manganese phase diagram. This deposition can be removed by using suitable filtration process and removal efficiencies were 33%, 22%, 11% and 0 with concentration of Calcium hypochlorite of 0.6 ppm, 0.7 ppm, 0.8 ppm and 0.9 ppm respectively. That need to be confirmed by further studies because raw water sample may have different cations and anions.
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    Study of Cation Exchange Properties of Selected Sri Lankan Coastal Soils with Sea Water
    (Uva Wellassa University of Sri Lanka, 2013) Premathilake, D. S.; Udagedara, D. T.; Jayawardana, D. T.
    Ion exchange is a naturally occurring process that depends on several physical and chemical factors. In general, geology and climatic condition of an area are the major factors among them. Geology and climate are the controlling parameters to develop different soil types in a given area. Also, texture and other physical properties such as pH and oxidation reduction potential (ORP) effectively control the ion exchange properties in the soil. In Sri Lanka larger area of the island is covered with crystalline rocks of Precambrian age and has distinguish four major basement units (Cooray, 1984). Considering climate of the island the dry, wet and intermediate climatic zones are defined on the basis of rainfall. In other words climatic zones of Sri Lanka are divided based on the annual rainfall of the island based on detail demarcating inthesouthwesternregion of the countryincluding western part of thecentralhillcountry, DryZone predominantly covering north, north-east and eastern sectors of th ecountry. Intermediate Zone identified between the Wet and Dry zones. Moreover, for the separation of aforesaidmajor climatic zones,landuse, forestry,rainfallandsoilshavebeenwidelyused (Herath and Pathirana, 1983). Due to different geological settings and diverse climatic variations of Sri Lanka various soil types are formed. Since its special geographical locality there is a higher possibility to contaminate soils with sea water. Such possibilities are accounts Tsunami, Tidal effects and inland river sand mining. Therefore there is a possibility to contaminate sea water with pure natural soils. Therefore main objectives of the study is to find the ion exchange properties of natural soils in Sri Lanka with sea water. Results will able to investigate ion exchange capacity with respect to physico-chemical properties of different soils such as pH, Oxidation reduction potential and conductivity.