Browsing by Author "Premachandra, N. P."
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Item Assessing the Suitability of Groundwater for Drinking Purpose in Paddanichupuliyankulam, Veppankulam and Nelukkulam in Vavuniya Divisional Secretariat Division(Uva Wellassa University of Sri Lanka, 2018) Reva, K. V. M.; Premachandra, N. P.The groundwater is the primary source for drinking purposes in Vavuniya, which is located in northern part of Sri Lanka. Agricultural over application of Nitrogen fertilizers and rapid urbanization are the main causes for the contamination of drinking water supplies. 50 borehole wells located in Veppankulam, Nelukkulam and Paddanichupuliyankulam in Vavuniya Divisional Secretariat Division were assessed for selected physio-chemical parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Hardness, Calcium, Magnesium, Nitrate (as NO3-) and Phosphate. The objective of this study was to assess the suitability of groundwater for drinking purpose based on the Sri Lanka Standards for potable water of SLS 614: 2013. In this study pH, EC and TDS were measured on the field, the Ultraviolet Spectrophotometric Screening Method was used for the detection of Nitrate and Phosphate concentrations, and Calcium and Magnesium were analyzed using Atomic Absorption Spectrophotometer. Nitrate, EC, TDS, Total Hardness, Calcium and Magnesium exceeded the maximum permissible levels in 70%, 96%, 42%, 80%, 53% and 100% of wells, respectively and the values varied in the ranges of 2.1 — 222 mg L-1, 462 — 8240 𝜇S cm-1, 323 - 7480 mg L-1, 172 1408 mg L-1, 56 - 419 mg L-1 and 114 - 989 mg L-1, respectively. Phosphate concentrations were below the maximum permissible level in all the wells and varied from 0.01 to 0.68 mg L-1. The pH was within the standard range in all the wells and varied from 6.97 to 8.35.Item 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.Item Efficiency Comparison of Three Types of Constructed Wetlands for Treating Reverse Osmosis Rejects(Uva Wellassa University of Sri Lanka, 2018) Ranathunga, P. G. K. B.; Premachandra, N. P.Reverse osmosis is a water purification technology that uses a semipermeable membrane under pressure to remove particulate and dissolved contaminants mainly pathogenic microorganisms, organic compounds, hardness and heavy metals. Use of this technology has increased tremendously to treat ground water in the Chronic kidney disease of unknown etiology prevalent areas in Sri Lanka in recent years. However, the need to treat reverse osmosis rejects (concentrated residue stream of reverse osmosis process) before releasing to the environment has not received much concern yet. Constructed wetland is one economical technique to treat reverse osmosis rejects. In this study efficiency of three different types of constructed wetlands were analysed. Three constructed wetlands were prepared, first one (CW1) only with soil, second one (CW2) with plantation of Schcenoplectus grossus (Thunhiriya) on the same soil and the third one (CW3) without soil with Water Hyacinth (Japan Jabara), an aquatic plant. The wetlands were created at a hydraulic retention time of 4 days with dimensions of 0.6 m x 0.3 m x 0.2 m. Removal efficiency of eleven parameters including concentration of nitrate, total alkalinity, total dissolved solids, total hardness, electrical conductivity, pH and heavy metals such as calcium, copper, manganese, magnesium, and cadmium were evaluated in all three wetlands. Results showed that all three types of wetlands have considerable efficiency in removing selected parameters, but CW2 was more prominent in removing the selected parameters except for magnesium, nitrate and electrical conductivity. Removal efficiencies of those three parameters were slightly lower in CW2 than CW1, and the reason could be carrying of nutrients to the CW2 at the plantation step. According to the results, it is, possible to conclude that a constructed wetland including soil and a plant is more efficient in the treatment of wastewater than a wetland which contains only soil or an aquatic plant.