Browsing by Author "Makehelwala, M."

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    Effects of Water Chemistry on in-situ Deposition of Mineral Phases at Kandy South Water Treatment Plant
    (Uva Wellassa University of Sri Lanka, 2013) Saumyarathna, N.G.R.; Weragoda, S.K.; Makehelwala, M.
    January 2010. The main function of this plant is to treat raw water abstracted from the Mahaweli Ganga (River). This plant is designed to produce 35,000 m /day of drinking water. The water treatment facilities comprise: 1) Intake section, 2) Treatment processes, including aerator, lime and alum feeding, pulsators, sand filters, backwashing system, post chlorination and neutralization system; 3) Storage; 4) Sludge Treatment; and 5) Other accessories, including supervisory control and data acquisition (SCADA), programmable logistic controls (PLCs). The possible effect of water chemistry on in-situ deposition of mineral phases at KSWTP has been analyzed in this study. Brownish black color depositions are found inside the casing, impellers and on the surface of the moving parts of the Non Return Valves (NRV’s) at KSWTP. Water in the channel at the service outlet of instrument is black color. It is also noticed that black–brown color deposition on walls of clear water reservoir. Dissolved elements such as Mn, Si, Al, Ca, and Mg in natural water form mineral deposition with different temperature and pressure. Thus, these elements may be causative factors. Deposition results when dissolved ions in the water exceed the solubility of a given mineral (Sly et al, 1990). Methodology Deposit samples were analyzed using Energy Dispersive X-ray Fluorescence (EDX) method which can directly determine the metal content in the solid material. Wet samples were analyzed to determine the bacteriological effect of manganese deposition.Water quality of different treatment processes was measured each week during the month period. Chemical water quality parameters were analyzed using various analytical methods. Major and minor ions were measured using titrimetric and spectroscopic methods using Varian SpectrAA 240 AAS available at the UvaWellassa University and as Atomic Hach DR 5000 as UV/Vis spectrophotometer. Other physical properties were measured with standard methods. Possible mineral phases of different ion concentration with different pressure and temperature were stimulated using Visual Minteq software.
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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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    Water pollution study in Nalanada Lake to improve the Water quality of Naula Water Treatment Plant
    (Uva Wellassa University of Sri Lanka, 2015) Nawarathna, T.N.T.K.; Makehelwala, M.
    Water is the largest natural resources of Sri Lanka although only a relatively low percentage of total population is getting safe and clean water for daily use. Water is using for Drinking, bathing, washing, and cleaning. Beside it is used for agriculture, industrial, hydropower generation. The Nalanda reservoir located in Naula, Matale district is the main water source of Naula Water Treatment Plant of National Water supply and Drainage Board (NWSDB). On the other hand NWSDB faces a big problem in the dry season because pumping water had a less amount of Dissolved Oxygen (DO) and occurring black color in pumping water. The dissolved oxygen (DO) concentration is a primary measurement of a stream’s healthiness. The dissolved oxygen concentration responds to the biochemical oxygen demand (BOD) load. Investigators have continuously studied the dissolved oxygen uptake characteristics in stream water in relation to different sinks and sources in order to develop mathematical models describing the DO consumption. In this reservoir percent high amount of Algae due to high nutrients content such as nitrate and phosphorous and change that algae type seasonally. One of the objectives of this research study is that Nitrate and Phosphorus variation in reservoir. And Main Objective was identification of the Dissolved Oxygen (DO) Variation in Nalanda reservoir. Methodology In this study six sampling location points were selected and studied the variation of nitrate, phosphorous and DO of these sampling points for four weeks of time. These data were collected in rainy and dry season. Samples were collected from the different distances from the intake of Naula Water Supply System. Totally 24 samples were collected from the upstream of the reservoir. Basically, the selected pollution points are surrounding point of the reservoir. Samples were taken from different morphological units of the reservoir. DO was analyzed at the sample collected points and COD and BOD also analyzed using the Standard laboratory procedures. Finally DO concentration variation was analyzed by using mathematical model called Streeter- phelps. Results and discussion Eutrophication of water body is occurred under high nutrients. The nutrients such as nitrate and phosphate distribution within selected pollution points in Nalanda reservoir is shown in figure 1. The recommended phosphate level for maintaining healthy water to minimize algae growth is 0.1 mg/L and nitrate level is 10 mg/L (USEPA). The results shown below indicated that the nitrate level was within required limit and phosphate level was exceeded limit. Therefore, phosphate consuming algae species can occur in Nalanda reservoir during this period.