Browsing by Author "Gunarathna, A.M.T.N."

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    Identification of mineral deposition at Akurana distribution line of Greater Kandy Water Treatment Plant
    (Uva Wellassa University of Sri Lanka, 2013) Gunarathna, A.M.T.N.; Weragoda, S.K.; Makehelwala, M.
    A water distribution network cannot be considered an inert system but a reactor interacting with the interior aqueous environment. One of the main consequences of such interaction is the formation of unwanted deposits. The main sources of deposits in water distribution systems are particulate matter transported by water, microbial activity and physicochemical reactions both at the water pipe wall interface and within the water bulk (Chawla et al, 2012). Greater Kandy water treatment plant is situated at Katugastota in the Central province of Sri Lanka Mahaweli river water taken as raw water is treated and distributed to the Northern part of Central province. This plant has four transmission lines to distribute water. Those lines are Asgiriya (A1),Gohagoda (A2), Kahawatte (A3), and Yatiyawala (A4). A3 transmission line transmits water to Kahawatte and it distributes water to Akurana area. The reddish brown color deposition can be observed, when flushing of the ductile iron pipes at pumping main of the Akurana distribution line at Greater Kandy Water Treatment Plant. Natural river water containing dissolved ions such as Ca, Mg, Al, and Si etc which can form stable mineral phases. Those minerals can be deposited in distribution lines when they meet the favorable conditions to form possible mineral phases. In this research, we will try to identify possible mineral phases are formed by using VMINTEQ software. Materials and methods Water samples analysis was related to identification of causing factors of mineral deposition at raw water and treated water. Samples were collected from plant, Akurana reservoir and Akurana distribution lines. In plant samples were collected from raw water from intake, distribution chamber, after flocculation tank, after sedimentation, filter inlet, filter outlet, and Sump. Two distribution samples were collected from near the Akurana reservoir and at Akurana town. pH, turbidity , electrical conductivity and colour were measured. Nitrate, nitrite, fluoride, Iron concentration of water was rechecked by using AAS (Atomic Absorption Spectrophotometer). Powder fillers were used to measure ions by using UV spectrophotometer. Ferro Ver, SulfarVer 4, Nitro Ver 3, Nitro Ver 5, PhospoVer were used as powder fillers to measure iron, sulfate, nitrite, nitrate and phosphate respectively. Different colours were given according to element contained in samples. Ammonia was measured by adding mineral stabilizer, polyvinyl Alcohol and Nesslar reagent, using spectrophotometer. Fluoride was also measured by adding SPANS using spectrophotometer. Chloride was measured by using digital titration method. Hardness and Alkalinity were measured by using titration method. Then deposited sample was collected from a tap which carrying sump water, was centrifuged and dried. It was analyzed using X-ray diffraction method (XRD) at Chemistry laboratory of Peradeniya University. Visual MINTEQ software was used to analyze water quality data and possible mineral phases that form deposits.
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    Identification of Mineral Deposition at Akurana Distribution Line of Greater Kandy Water Treatment Plant
    (Uva Wellassa University of Sri Lanka, 2013) Gunarathna, A.M.T.N.
    Water quality of distribution system depends on chemical, physical, and Biological parameters of water. Natural river water contain dissolved minerals such as Ca, Mg, Al, Si, Fe .etc which can be formed stable states of its amorphous minerals. Those amorphous minerals can be deposited in distribution lines when the favorable conditions exist to form possible mineral phases. The mineral deposition and its kinetics are depending on temperature and pressure. Brownish colour deposition forms in distribution lines because of Fe deposition. When water contains oversaturated Fe concentration, the deposit is formed. In this research consider about possibility of forming Fe deposits inside the Akurana distribution system and deposit composition. Samples were collected from inside premises of Greater Kandy Water Treatment Plant and Akurana Distribution lines. Then sample's water quality was checked and analyzed by using Visual MINTEQ software. According to analyzed data, there is possibility to form Maghemite deposition in Akurana distribution line and plant premises. The deposited sample which was collected from tap near to Sump (sump water carrying tap) was analyzed by XRD analysis and the obtained results showed moderately same d values (indicate what is this) with standard Maghemite spectrum. Results were shown in appendix 03. So it confirmed that deposit is mainly consisting of iron oxide which is called Maghemite.