Browsing by Author "Weragoda, S. K."

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    Determination of a Suitable Treatment Methodology to Treat Rice Washed Water Released from Rice Mills
    (Uva Wellassa University of Sri Lanka, 2019-02) Abhilasha, K. M. G. D.; Weragoda, S. K.; Premachandra, N. P.; Weerasekara, W. B. M. L. I.
    In this experimental study, the wastewater eliminated from the rice washing in the rice mills is taken into account. This wastewater possess very high COD, BOD and turbidity and do not comply with the wastewater discharge limits imposed by the National Environmental Regulations No 01 of 2008 of Central Environmental Authority. Five methods were used to treat the rice washed wastewater and its efficacy have been analyzed mainly through the variation of Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). By doing this research, it is intended to obtain water that is suitable to discharge into the environment. The five methods tested are, biological treatment method by using the Moving Bed Biofilm Reactor (MBBR), physical method by applying heat, chemical treatment by using 99% alum, treatment with hydrogen peroxide and ferrous sulfate and finally by treatment with activated carbon. In the MBBR treatment, COD and BOD removals were 53.15% and 29% respectively. On heating, the most efficient COD and BOD removal was obtained at 45oC. Adding 99% alum did not show any efficacy towards the removal of COD and BOD. When 200ml of raw water was treated with 30% hydrogen peroxide 5 ml, and ferrous sulfate 0.6 g, and overnight stirred, COD and BOD removals were 85.7% and 88% respectively. When 200 ml of raw water was treated with 0.5 g of activated carbon, the COD and BOD removals were 87.5% and 90% respectively. From the results obtained, it can be concluded that using activated carbon is the most efficient among the treatment methods used for removal of COD BOD and turbidity and using hydrogen peroxide and ferrous sulfate too can be considered an efficient method as it too has a higher removal percentage of COD and BOD. MBBR treatment is a moderately efficient method. Applying heat and using alum are inefficient. From the data obtained from Fourier Transform Infrared Spectroscopy, the substances responsible for the rise of COD and BOD were recognized.
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    Investigation of Trihalomethane Formation in Kandy South Water Treatment Plant and Distribution System with Other Water Quality Parameters
    (Uva Wellassa University of Sri Lanka, 2016) Rathnasiri, T.C.; Amarasooriya, A. A. G. D.; Weragoda, S. K.
    In most of the cases where chlorination use as disinfection method it will lead towards the byproduct formation, mainly the trihalomethanes (THMs). During the investigation, 74 water samples were taken from the Kandy South Water Treatment Plant, 13 service reservoirs, and user end points and analyzed for THMs and other water quality parameters. Results were used to calculate the correlation between THMs and other water quality parameters. Trichloromethane (TCM) and bromodichloromethane (BDCM) were the major disinfection by-products found in treated water samples of Kandy South distribution system. DBCM and TBM were not detected in any of the samples. For the formation of BDCM there should be a possible bromine source in raw water. TCM was the most abundant THMs with the concentration ranged from 0 to 42.47 µg/L. Second abundant was BDCM and it ranged 0 to 13.0 µg/L. Total THMs found in Kandy South distribution system ranged from 0 to 54.85 µg/L. Distribution THMs formation depends on various factors such as residual chlorine, pH, conductivity, TOC but there are many significant relation with distance from WTP and service reservoirs. Average level and highest levels of TTHMs in water supply schemes of KSWTP were not exceeding WHO 8011g/L standard value. But long exposure of THMs in KSWTP will be a threat to consumer's health Keywords: Disinfection, Chlorination, Trihalomethanes, Kandy south water treatment plant, By-products
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    Investigation of Trihalomethanes formation in Greater Kandy Water Treatment Plant and its distribution
    (Uva Wellassa University of Sri Lanka, 2015) Perera, M. G. N.; Weragoda, S. K.
    No doubt that chlorination has been successfully used for the control of water borne infections diseases for more than a century. Halogenated trihalomethanes (THMs) and haloacetic acids (HAAs) are two major classes of disinfection byproducts (DBPs) commonly found in waters disinfected with chlorine (Rook, 1974). The formation of the Trihalomethanes (THMs) was investigated in Greater Kandy Water Treatment Plant (GKWTP) and distribution system which serve drinking water to Kandy region, located in the middle province of Sri Lanka. Water samples were taken from storage tank of GKWTP of the National Water Supply and Drainage Board (NWS & DB), covering selected water quality and operational parameters that have direct influence on THM formation. In addition THM formation at the distribution extremities were also studied. Methodology Water samples were taken from storage tanks of GKWTP after the chlorination of initial dosage of 2 ppm chlorine. Water samples of 32 taken from selected distributed within six Divisional Secretariat Divisions for the analysis. Primary Trihalomethanes were analyzed using Gas Chromatography – ECD (Kuivinen, 1999). Formation of Trihalomethanes were analyzed in storage tanks for 64 hours by doubling time and level of Trihalomethanes in distribution system. Apart from THMs, pH, temperature, turbidity, were analyzed in raw water and treated water collected at sampling points by pH meter, thermometer and turbidity meter respectively. Treated water was also tested for free chlorine level and total chlorine level to observe impact on THM formation by those parameters by colorimeter. Result and Discussion Measured THMs and other parameters for storage tanks in GKWTP summarized in Table 1 and indicate in figure 1. This indicate that the trihalomethanes increase with the time in storage tanks. Initially mean TTHMs was 17.09 µg/L when the initial dose of chlorine of 1.85 mg/L. When doubling the reaction time formation of THMs were increased and finally it became 40.72 µg/L when reaction time become 64 hours. Table 1 indicates that the free chlorine and total chlorine decaying with time. Temperature is constant for the whole analysis as 25 C, as it highly depend on temperature. Concentrations of CHCl3, CHCl2Br and TTHM of sampling locations indicate in Table 2 in 32 sampling points. Table 2 summaries descriptive statistics for individual and total THMs (TTHMs) with free chlorine in the water samples of distribution system. Highly variable range of TTHMs concentrations were found (11.275 to 22.976 µg/L) in distribution system. Chloroform (CHCl3) concentrations contribute a significant portion to the TTHMs (76%) while Bromodichloromethane (CHCl2Br) contribute 24%. Regression model for GKWTP. The regression equation is: TTHM (µg/L) = 19.5 + 0.00580 Time (min) R-Square (adjusted) value = 95.9%; p < 0.05 Conclusions When considering storage tanks conclude that the formation of trihalomethanes depend on reaction time and free chlorine while temperature, pH, turbidity remains constant. CHCl3, CHCl2Br and TTHMs levels at all locations were found lower than the guideline values regulated in WHO and USEPA which is lower than 25 µg/L. Due to the free chlorine ranges to 0.2 to 0.7 mg/L in distribution system, conclude that residual chlorine exceeding its standard value of 0.2 mg/L for drinking water. Variation of trihalomethanes and free chlorine values of storage tanks and distribution system, assume that chlorine reactions take place and evaporation of free chlorine during analysis. Other two compounds of trihalomethanes such as Dibromochloromethane (CHClBr2), and Bromoform (CHBr3) could not be detected in GKWTP.
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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.