Browsing by Author "Weragoda, S.K."

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    Assessment of the Impact of Azolla pinnata at Demodara Water Treatment Plant Intake Reservoir
    (Uva Wellassa University of Sri Lanka, 2019-02) Jayasinghe, N.S.; Weerasekara, W.B.M.L.I.; Udagedara, T.; Weragoda, S.K.
    Demodara Water Treatment Plant intake reservoir is located in between Demodara and Badulla cities about 12 km upstream in Badulu Oya from Badulla. An invasive growth of floating macrophyte was observed from third week of January 2018. Water quality of treatment plant intake reservoir was studied by analyzing the reservoir water with the presence and the absence of the Azolla mat, to find whether there was any change in the water quality with the mat. Water quality close to the dam, lake at about 1 km upstream from the dam and upstream flowing water (about 500 m upstream from the lake) were analyzed in different depths (close to the dam 6.5 m and upstream lake 1 m depth). pH, turbidity, electrical conductivity, dissolve oxygen was analyzed on site and NO3-, Total PO₄ 3- , SO42-, Cl- and F- was measured using Ion Chromatograph and relative abundance of phytoplanktons were estimated using plankton nets (20 μm) and microscope with the presence of A. pinnata mat and following day of removal of A. pinnata mat. As a part of the study, two models were observed inserting 20 l of intake reservoir water and 22 g of Azolla for one model. pH, turbidity, conductivity was monitored for seven weeks. pH was decreased in the model with Azolla. Conductivity and turbidity did not show a significant change. pH decrement and Total PO₄3-, Phytoplankton increment was observed with the absence of the mat in Demodara reservoir. All the water quality parameters in treatment plant raw water were within the drinking water standards (SLS 614:2013), with the presence of Azolla mat. The Azolla didn’t appear after manual removal. Therefore, further studies and implementing a Water Safety Plan by proper catchment management is needed.
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    Determination of Raw Water Quality Parameters and Reasons for Failures in Hantana Sewerage Treatment Plant, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2012) Ritigala, H.M.T.S.; Weragoda, S.K.; Kodhithuwakku, S.
    Many health hazards in developing countries and transition-economic countries are related to poor water quality and limited water quantity (Vandeweerd et al., 1997). According to Vandeweerd et al. (1997), more than 90% of sewerage in the developing world is discharged directly into rivers, lakes, and coastal waters without any treatment. Sri Lanka also faces a number of water and wastewater issues and water related health hazards (WHO, 2000). The large cities such as Colombo, Galle, Jaffna and Kandy have serious problems disposal of sewerage, industrial effluents and industrial and of domestic solid waste, as they generate large quantities but have no facilities for their treatment and/or proper disposal (Bandara, 2003). Moreover, Kandy suffers from a serious problem of wastewater disposal which contributes to the pollution of Mahaweli River. There is no proper system of wastewater disposal, and about 80% of used water is released as wastewater (Thrikawala et al., 2008). In addition, highly polluted water is carried by tributaries like Meda-ela, Pussellawa Oya, and Pinga Oya, which connect to Mahaweli River (Dayawansa, 2006). Pussalla Oya catchment was the main source area for the "Hepatitis A" outbreak recorded in Gampola in May 2007 (Abeysinghe, 2007). Due to lack of the knowledge of health hazards by wastewater or scarcity of resources, sewerage treatment and/or improved sanitation were not given due attention by most communities. According to Gijzen (2001) there have been substantial developments in wastewater management and treatment technology. As a solution to the discharge of untreated wastewater, sewerage treatment plants (STPs) have been constructed especially in rapidly urbanizing cities. Main purposes of this research are study the system and find out the reasons for failures and defect identification in Hanthana STP. Determination of the raw water quality parameters, propose the alternatives for occurring issues and waste discharge per day are also considered in this study
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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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    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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    Optimization of Pre-Treatment Process of Iron Removal from Groundwater
    (Uva Wellassa University of Sri Lanka, 2018) Manathunge, M.D.R.M.; Weragoda, S.K.; Weerakoon, W.M.D.S .; Weerasekara, W.B.M.L.I.
    The presence of iron is one of the major issues experienced by groundwater consumers. The rural water treatment plant located at Bolagala area in Kandy treats water mainly for iron removal. The available half treatment process of this plant removes 83.20 - 93.06 % iron from natural water. As the raw water iron concentration is high, the removal percentage is not adequate to bring the iron concentration down to the recommended standards (SLS 614: 2013). The study was carried out to optimize the existing pre-treatment process with the purpose of bringing the treated water iron concentration under 0.3 mg/l. Two oxidation processes a) Aeration b) Chlorination were experimented to select an optimum oxidant. Aeration was tested for different time periods. 6 min aeration time showed approximately 50% removal of dissolved iron concentration. Chlorination was tested for different doses. 5 ppm chlorine dose was effective in 99% removal of the dissolved iron. The final dissolved iron (DI) concentration reached 0.03 mg /1 which is ten times lower than recommended level. The plant pre-treatment step should include a chlorination step with aeration to achieve the optimum removal of dissolved iron in raw water.
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    Relating climatic parameters with leachate chemistry and its association with river water quality
    (Uva Wellassa University of Sri Lanka, 2015) Weerakoon, W.M.D.S.K.; Weragoda, S.K.; Kalpage, C.S.K.; Ziyath, A.M.; Manipura, A.
    Increased solid waste generation due to rapid urbanization and industrialization is a major problem in the world (Golomeova et al. 2013). .Landfilling is the most common disposal method of municipal solid waste (MSW) in developing countries, even though majority of these landfills are not properly managed, and pose a serious threat to the environment due to leachate run-off which contaminates the nearby ground water and surface water bodies (Kjeldsen 1993). The quantity and quality of leachate is influenced by various factors and climatic conditions are one of these governing factors (Chu et al. 1994; Johansen & Carlson 1976). Hence this study was carried out focusing on the impact of climatic parameters on leachate quality and its association with the Mahaweli river water quality which has not yet been further studied. Meantime two main objectives were fulfilled during the process of reaching the main target. They were, investigating seasonal variation of leachate chemistry and Mahaweli river water quality and developing correlation between climatic parameters, leachate chemistry and Mahaweli river water quality. Materials and methods Landfill leachate ,river water samples and ground water samples were collected from the leachate drain of the Gohagoda landfill, four locations along the Mahaweli river- two upstream and two downstream points from where leachate drain to the river and from two wells within the landfill. Weekly sampling was carried out for a period of two months and sample preservation, storage and analysis were performed according to Standard Methods (APHA, 1999). Daily temperature and rainfall data were collected from Horticultural Crop Research and Development Institute (HORDI) Gannoruwa and the statistical computations were performed with MINITAB version 17.0. Results and Discussion All the measured leachate and water quality data are summarized in Table 1.As the first step, primary leachate characteristic values were being compared with the past studies (Wijesekara et al.) and with the recommended standards of tolerance limits for discharge of effluent for inland surface waters by the Central Environmental Authority (CEA). Alkaline pH value represented the methanogenic stage of the landfill(More than 10y of operation) and exceed the CEA value. TDS and EC values of the leachate were very high (1.33× 10 mg/L & 2.05×10 µs/cm) compared to other sites. Dissolved Oxygen showed a very low value (0.09 mg/L) at the leachate drain owing to the anaerobic conditions and oxidisable organic matter related components are measured as BOD and COD. Both of these components were exceeding the CEA values. BOD:COD ratio was stated as 0.911 representing acidogenic condition which contrast with the above results. It is obvious that the uncontrolled dumping of the waste can produce leachate with various ages due to the irregular degradation pattern of the refuse material.(Wijesekara et al).
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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 ÷ 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.
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    Risk Assessment and Health Based Evaluation on Rural Water Supply Schemes: Case Study in Kotiyakumbura, Mawela and Kandewaththa
    (Uva Wellassa University of Sri Lanka, 2019-02) Edirisinghe, E.P.M.; Rajapakse, R.M.S.M.; Weerasekara, W.B.M.L.I.; Weragoda, S.K.
    Provision of safe drinking water and sanitation facilities are cited as the highest social priority to communities. In Sri Lanka, rural water supply schemes are not subjected to substantial concern. This research was to focus on health-based evaluation on treated water from rural water supply schemes. Hazards and hazardous events were identified at the water source, treatment process, distribution system and the consumer end of three rural water supply schemes. The risk assessment was carried out following semi quantitative approach. 40% of the identified hazards were recorded as high risk. Turbidity, Electrical conductivity, pH, Temperature, Alkalinity, Hardness, Nitrate, total phosphate, Phosphate, E. coli and total coliform were measured in raw water, treated and water from consumer end. Residual Chlorine was measured in treated and consumer end water samples. Tested water quality parameters were within the limits of Sri Lankan Standards except the pH of treated water in Kotiyakumbura, turbidity of Kandewaththa. Kotiyakumbura and Mawela treated water is microbiologically unsatisfactory. The pH of water in Kotiyakumbura ranges between 5.98 and 7.40. 90% of the turbidity of water at the consumer end in Kandewaththa exceeds 2 Nephelometric Turbidity Unit. Questionnaire survey was done by covering the income levels, education backgrounds and location. Kandewaththa consumers do not use this water for drinking. Currently, none of the consumers are suffering from waterborne diseases. 82% of Kotiyakumbura and 78% of Kandewaththa consumers practice domestic water treatments such as boiling and filtering. Due to these domestic treatments they may be free from water-borne diseases currently. As a recommendation it is necessary to implement Water Safety Plans on rural water supply schemes. Further studies are required on rural water sector to improve the quality of treated water.
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    Social Impacts on Rainwater Harvesting – A Case Study in Anuradhapura and Kegalle
    (Uva Wellassa University of Sri Lanka, 2019-02) Rathnayake, K.A.I.L.; Weragoda, S.K.; Weerasekara, W.B.M.L.I.; Udagedara, D.T.
    Water scarcity is a global issue with the increasing population. Rainwater harvesting is considered as an environmental friendly, sustainable source of water which can be used for domestic and drinking purposes. Sri Lankan government has framed rules and policies supporting the installation of rainwater harvesting systems, however, implementation and operation of these require the acceptance and willingness of general public. This research focuses on the social impacts on the rainwater harvesting systems installed in dry and wet zones in Sri Lanka. Both, water quality (Physical, Chemical, Bacteriological) and factors affecting it were assessed through the study. The samples were collected from rainwater harvesting systems at Kegalle and Kebithigollewa regions, 30 from each while conducting a questionnaire survey simultaneously. pH values were varied between 5.53- 7.19 in Kebithigollewa and 6.49 – 9.55 in Kegalle, may be due to the reactions in the tank material, ferrocement and plastic. All the tested chemical parameters of rainwater samples were within the limits of SLS 614: 2013 guidelines. Total coliform was detected in 50% of Kebithigollewa samples and 100% of Kegalle samples, which may be due to wrong water quality and quantity management practices. Social survey analysis revealed that microbiological parameters were affected mainly by the cleanness level of roof catchment area and atmospheric conditions, such as dust in the environment. Consumers in Kegalle region hesitate to drink rainwater due to lack of confidence as a drinking source. Harvested rainwater can be of consistently high quality through the selection of appropriate catchment, storage materials and the application of post-cistern treatment. A water safety plan should be implemented on rainwater harvesting systems to identify the risks, to improve the water quality and to mitigate quality degradation. A social awareness programs can be recommended to increase the rainwater consumption and willingness.