Browsing by Author "Premachandra, N.P."

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    Comparison of the Effectiveness of Hydrilla, Water Hyacinth and Water Lettuce in Treating Domestic Wastewater
    (Uva Wellassa University of Sri Lanka, 2019-02) Amarakoon, A.M.S.N.; Premachandra, N.P.
    The effectiveness of three aquatic macrophytes to improve the quality of domestic wastewater was evaluated. Growth of the Water lettuce (Pistia stratiotes), Water hyacinth (Eichchornia crassipes) and Hydrilla (Hydrilla verticillata) were inhibited in undiluted domestic wastewater. Therefore, diluted domestic wastewater series was introduced as 30%, 20% and 10% and all three macrophytes grew successfully in the diluted series. Chemical Oxidation Demand, Biological Oxidation Demand, Dissolved Oxygen, NO3- as N, PO43- as P, pH, Oil and grease, alkalinity and acidity were analyzed as water quality parameters at the beginning and 3rd day, 6th day and 9th day after introducing macrophytes. All three aquatic macrophytes improved the quality up to the permissible levels of wastewater discharging during 9-day period. According to the performance of all three macrophytes, water lettuce is the most effective macrophyte for treating domestic wastewater within the shortest time period (3-day hydraulic retention time). Controls of the each dilution to which macrophytes were not introduced, the quality did not reach to the wastewater discharging permissible levels at any quality analyzed point within the 9day period. A model was introduced to households for treating their own domestic wastewater using the findings of this study. In the model, domestic wastewater flows through a pipeline and another pipeline is connected with water to dilute the wastewater. To achieve the 30% dilution, 35 L of water should be supplied to 50 L volume domestic wastewater treating tank (0.41 m diameter, 0.37 m working depth) which contains inlet and outlet pipelines designed with baffle walls to keep 3-day hydraulic retention time. Introducing about 100 g fresh weight of Water lettuce at the beginning is sufficient to function this model. Treated water is flowing through the outlet after 3-day period and the water can be discharged to a surface water body or to the land surface.
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    Compliance of Wastewater Standard by Textile Industries at Board of Investment - Biyagama Export Processing Zone (BOI - BEPZ)
    (Uva Wellassa University of Sri Lanka, 2019-02) Nanayakkara, T.S.; Premachandra, N.P.
    Untreated wastewater is responsible for variety of environmental and health problems. In BOI-BEPZ there are 11 textile and dying factories, and wastewater generation is approximately 7800 m3 day-1. These industries have their own wastewater treatment plants to treat wastewater chemically in-house until it meets zone’s tolerance limits for industrial wastewater discharge into common wastewater plant. However, these in-house treatment plants have many drawbacks and also the effluent water quality does not meet the tolerance limits given by the Board of Investment. These violations impair the performance of the common wastewater treatment plant. The main objective of this research is to investigate the compliance of the wastewater with the limits for discharge to the common wastewater treatment system in the zone and to identify reasons in case of noncompliance. In-house treated wastewater was collected from selected textile industries in the zone. Physio-chemical parameters such as pH, Temperature, Biochemical Oxygen Demand, Chemical Oxygen Demand, Total Suspended Solids were analysed. After analysing it was identified that ten out of eleven factories that were investigated, exceeded at least one of the above parameters. All treatment plants mainly use chemical treatment processes for wastewater treatment, and the amount of chemical needed to bring wastewater to compliance limit is high. Further, these chemical processes produce high load of sludge usually exceeding 50,000 kg month-1, spending high amount of money on sludge disposal. Therefore, this study suggests alternative methods to treat the wastewater by which the amount of chemical usage is reduced so that the cost on the chemicals and the amount of sludge formed is reduced.
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    Effect of Contact Time and Absorbent Dose on Limestone for Removal of Total Dissolved Solids from Industrial Wastewater
    (Uva Wellassa University of Sri Lanka, 2020) Palihawadana, K.P.; Premachandra, N.P.
    Commonly the food processing industry consumes a huge amount of water. Food industry effluent characterizes high Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Dissolved Solids (TDS), fats, nutrients, oil, and grease. Fish processing wastewater mainly shows high TDS due to releasing of blood, small pieces of fishes, and chemicals at the filtering, cooling, washing, cooking, pre-cooking, and thawing steps. High TDS can be interference for wastewater treatment steps like biological treatment and this situation, a cost-effective pre-treatment is suitable. Adsorption theory has also been used in previous researches to remove TDS, and in this research, the effect of contact time and adsorbent dose were investigated to remove TDS from fish processing wastewater. A batch test was performed using limestone as an adsorbent. Wastewater samples were kept at pH 7 using 0.1 N HNO3 and 0.1 N NaOH. Using sieve shaker, >0.063 mm, >0.125 mm, >0.15 mm, >0.5 mm, > 1 mm, >2 mm and >3.14 mm particle sizes were separated. As >1 mm particle recorded highest removal efficiency as 83.85% (adsorption capacity 1297.5 mgg -1 ). >1 mm particle was used for remaining experiments. When increasing contact time, the highest removal efficiency was recorded at 5-hour contact time as 72.55%. When increasing adsorbent dose, the maximum removal efficiency was recorded at 4 g L-1 as 79.64%. The results indicated that the removal efficiency of TDS depends on the adsorbent dose and contact time. Though, limestone is an alkaline material because of containing CaCO3 as a predominant material, with no high increment of pH in the wastewater sample after adsorption. Adsorption data also fitted with Langmuir Isotherm and according to results, this can be indicated as favourable adsorption. Keywords: Food processing industry wastewater, Limestone, TDS, Adsorption
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    Hardness Removal from Drinking Water Using Inorganic Ion Exchange Resin- Zeolite
    (Uva Wellassa University of Sri Lanka, 2019-02) Jayangani, K.C.; Weerasooriya, R.; Premachandra, N.P.; Jayarathna, I.P.L.
    The hardness of drinking water has become a major environmental problem at present and it has to be removed using cost effective technologies. This research focuses on using synthesized inorganic zeolite as an inorganic ion exchange resin for hardness removal. It is to be achieved by controlling the physical parameters on performance of zeolite in different hardness level of water. The research approach includes both batch and column experiments performed in laboratory condition to determine optimum level of zeolite on the removal process of Ca2+ and Mg2+ from water. A Batch contact time experiment was carried out with varying contact time for 10 g L-1 of a constant adsorbent mass at the concentration of 250 ppm for both Ca2+ and Mg2+. One hour was the optimum time. Accordingly, the experiment was carried out by varying adsorbent mass for different hardness level of Synthetic Hard Water (SHW). The different hardness level of water samples was reduced by 80-95% from 3-5 g dosage of zeolite. The data obtained from the batch adsorption system is not applicable for design a continuous adsorption system. Then, column sorption studies were carried out using fixed bed column, which was filled with sand and zeolite, mixed in 1:1. The influent flow rate and concentration of the SHW solution were kept constant at 12.7 mL min-1 and 100 ppm, respectively. The column was reached exhaustion after the 30 min, according to the breakthrough curve for the column. According to results, it can be concluded that synthetic inorganic zeolite can be used to remove hardness from all the hardness range of moderately hard water, hard water and very hard water in high percentage (80-95%).
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    Identification of Near Surface Water Flow Path in Kanniya Hot Water Spring
    (Uva Wellassa University of Sri Lanka, 2018) Chathuranga, H.D.N.; Subasinghe, N.D.; Premachandra, N.P.; De Silva, S.N.; Samaranayake, S.A.; Bandara, H.M.D.A.H.
    Although Sri Lanka is not located in an active volcanic region or in the vicinity of an active plate margin, the country possesses unexplored geothermal resources with potential for development as a source of renewable energy. As the present trend for geothermal prospects of low-enthalpy metamorphic terrains become a focus overriding conventional magmatic provenances, Sri Lanka is well placed to explore the same. Prospects for low to medium temperature geothermal resources can be expected to spread across the hot springs belt of Sri Lanka. Low to medium temperature geothermal resources have direct applications in food processing, fruit drying, refrigeration and recreational activities. Delineating the source characters of prospective geothermal fields in geological perspectives would be the initial step towards addressing this untapped energy source. Thorough geological mapping along with geophysical applications would pave the way for such source characterization. Geochemical analysis further provides necessary clues on the potential of the source, its provenance and temperatures. Among many geothermal fields that are scattered in the SE to eastern region of the island, Kanniya site was selected for this study. Objective of this study was to identify the near surface water flow path in Kanniya hot water spring which is one of the major hot spring fields located in Sri Lanka near Trincomalee. One-Dimensional and TwoDimensional resistivity survey and magnetic survey were used for subsurface layer mapping of the area and the results were synchronized with the elevation model. The results showed that the flow path is in Northeast - Southwest direction line receiving from beneath a quartz hump. According to the topography of the area, water flow is towards the sea in Northeast direction. Therefore, it is possible to conclude that the near surface water flow path in Kanniya hot water spring is towards the Northeast direction. Presumably the quartz layer acts as a conduit for such flow, due to its high permeability character.
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    Introducing a Cost Effective Treatment Process to Improve the Effluent Water Quality of Natural Rubber Processing Factories
    (Uva Wellassa University of Sri Lanka, 2016) Gamage, K.H.I.; Premachandra, N.P.; Ritigala, H.M.T.S.
    Most natural rubber processing factories in Sri Lanka tends to discharge their effluent water without treating properly or directly into the nearest stream as proper treatment processes reduce their profit. The objective of this study is introducing a cost effective and commercially viable treatment process to treat the effluent water generated from natural rubber processing factories. The proposed cost effective treatment process includes two treatment steps mainly as Pretreatment Process and Biological Treatment Process. In the Pretreatment Process Total Suspended Solids (TSS) and the Turbidity of the effluent water are reduced using a natural coagulant, and in the Biological Treatment Process the amount of Nitrate and Sulphate dissolved in the effluent water are biodegraded using facultative anaerobic bacteria. As the natural coagulant in the Pretreatment Process Bentonite clay is used and to increase the surface area for the growth of anaerobic bacteria in the Biological Treatment Process a bio brush media made up of bristle fibre coir is used. The effectiveness of proposed treatment process was analysed using effluent water samples collected from eight natural rubber processing factories. In the analysis pH, TSS, Turbidity, Total solids, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Sulphate and Nitrate contents were measured before and after the treatment process. The proposed cost effective treatment process can reduce the TSS content even below the permissible value of 100 mg/1(Turbidity and TSS reduction up to 97% and 54% respectively) and it can reduce the BUD and COD values very close to the permissible levels of 50 mg/l and 400 mg/lrespectively (BOD and COD reduction up to 79% and 70% respectively). Sulphate and Nitrate biodegradation efficiency is nearly three times higher when using the introduced bio-brush media as it increases the surface area for anaerobic microbial growth. As Pretreatment Process needs about 6 hours of contact period and Biological Treatment Process needs about 15 days of contact period, this process is more suitable for medium scale natural rubber processing factories where large amount of effluent water is not produced daily. Keywords: Waste water treatment, Biological treatment, Cost effective treatment
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    Study of Oil Contamination in Chunnakam Area due to the Wastage from Power Station
    (Uva Wellassa University of Sri Lanka, 2016) Thulasitha, W.; Premachandra, N.P.
    Jaffna Peninsula relies totally on groundwater resources for the water needs of its inhabitants as this karstic terrain does not have any other potable water sources. Chunnakam, Thenmaradchi, Vadamaradchi and Kayts are the four main aquifers in Jaffna Peninsula. Of these Chunnakam aquifer has the highest capacity and acceptable quality as a drinking water source and for other usages. However, its water has become completely unsuitable for drinking due to an oil contamination. The groundwater contamination is attributed to oil waste from a 36 MW diesel power plant operated by the Ceylon Electricity Board (CEB) located in Chunnakam - Valikamam part of Jaffna Peninsula. High levels of contamination have been reported from areas such as Earlali, Mallakam and Uduvil around Chunnakam. Irrespective of the magnitude of the hazard no systematic study on the spatial distribution of the subsurface contaminant distribution has been carried out so far. This study focuses on determining the extent of contamination of groundwater in Chunnakam. Groundwater samples were collected during mid-April 2015 from wells within 2km radius around the power station to represent different uses such as domestic, domestic with home garden, public wells and agricultural wells. Important chemical parameters, namely oil and grease content, electrical conductivity (EC), pH and heavy metals such as lead and cadmium were determined in water samples obtained from 40 wells. Oil and grease concentration was measured by EPA method 1664, Hexane Extractable Gravimetric method. The spatial variation of water quality was mapped on GIS. Analyses reveal that 33 (82.5%) wells contain oil concentration above the permissible level (1.0 mg/1). Only 3 (7.5%) wells showed oil concentration below the permissible limit while 4 (10%) wells were not contaminated with oil and grease. A reciprocal relationship is observed between the oil and grease content in the groundwater and the distance from the power station. It implies that the contaminant front is expected to migrate in the aquifer although the waste disposal has ceased. Spatial pattern of the contamination shows that it spreads more towards the north. Keywords: Oil contamination, Chunnakam power station, Water quality
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    Wastewater Treatment Solution for Vehicle Service Stations by Using Ultrafiltration Membrane
    (Uva Wellassa University of Sri Lanka, 2019-02) Wijesinghe, R.R.; Ritigala, H.M.T.S.; Premachandra, N.P.
    A vehicle service station is place where large amount of water is consumed for vehicle washing. This wash water includes contaminants which may cause adverse effects if not treated properly before discharge. Many treatment methods have been suggested by researchers to treat service station effluent. These treatment methods have drawbacks such as large space requirement, high chemical consumption, sludge production, not user friendly compact systems. With that the need for improved techniques to purify contaminated waters arises. Over the past decennia membrane technology has been introduced as a cost effective method to treat water in a smaller foot print. Therefore, a prefabricated membrane reactor using Ultrafilters was introduced to study the effectiveness of removing contaminants from service station wastewater. The treatment process included an oil trap and then the membrane reactor which included a sand filter, carbon filter and a micron filter as the pretreatment steps for the Ultrafilter. As analyzing part, the characteristics of wastewater for parameters such as pH, total suspended solids, oil and grease, biochemical oxygen demand, and chemical oxygen demand were measured in the raw water, oil trapped water and water sent through the membrane reactor. In the absence of any specific discharge standard, the outlet water quality was compared with the Sri Lankan standard for discharge of effluents to inland surface waters. The treatment process was able to keep the parameters within the tolerance limit values of the standards by removing 91.46% of total suspended solids, 98.8% of oil and grease, 78.71% of biochemical oxygen demand and 93.32% of chemical oxygen demand. As a result, this water can be safely discharged into the environment or can be taken into reuse purposes.