Browsing by Author "Bandara, W. M. J. Y."

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Assessing the relationship between water quality parameters and toxic cyanobacterial abundance in a hospital wastewater treatment plant
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Bandara, W. M. J. Y.; Sewwandi, B. G. N.
Cyanobacteria are a group of prokaryotes that thrive in various aquatic environments under favourable conditions such as high levels of nutrients, optimal water temperature, and light. The presence of cyanobacteria in wastewater treatment plants (WWTPs) is concerning, as certain species can produce toxins, posing significant health and environmental problems. Understanding the conditions that promote the growth of cyanobacteria in WWTPs is crucial for developing strategies to prevent or minimise their proliferation. Therefore, this study assesses cyanobacterial abundance with different water quality parameters at a WWTP in Matara District, Sri Lanka, which treats hospital wastewater generated from both black water and grey water. The aim of the study was to identify both toxic and non-toxic cyanobacteria, quantify their abundance, and analyse the relationship between toxic cyanobacterial abundance and various water quality parameters. Wastewater samples were collected from three sampling sites (Site 1- the sedimentation tank; Site 2 - post-chlorination tank; and Site 3 - the discharge field) in the WWTP for five months. Water temperature, pH, dissolved oxygen, total dissolved solids, salinity, electrical conductivity, total suspended solids, nitrate, and phosphate were analysed using standard protocols. Cyanobacteria cells were collected using a plankton net, identified with identification keys, and enumerated using the Sedgewick-Rafter counting method. Water quality parameters and cyanobacterial abundance were measured in triplicate at each sampling site. The relationship between the abundance of cyanobacterial species and water quality parameters was determined using Pearson’s correlation test in Minitab 19.0. Five toxin-producing cyanobacterial species (Oscillatoria sp., Phormidium sp., Limnothrix sp., Pseudanabaena sp., and Cylindrospermopsis sp.) and one non-toxic species (Spirulina sp.) were identified, with Phormidium sp. as the most abundant. The identified species showed varying correlations with water quality parameters. The abundance of Oscillatoria sp., Phormidium sp., Limnothrix sp., and Pseudanabaena sp. showed a strong positive correlation with total dissolved solids, electrical conductivity, and phosphate, indicating they thrive in nutrient-rich environments with abundant dissolved salts and phosphate. Phormidium sp. also showed a positive correlation with dissolved oxygen and nitrate, while Cylindrospermopsis sp. did not show any significant correlation with any parameter, indicating its growth was influenced by other factors. No cyanobacterial species showed a significant correlation with total suspended solids. Limnothrix sp. abundance correlated positively with water temperature, whereas Oscillatoria sp. and Phormidium sp. showed a negative correlation with water temperature. This study highlights that the WWTP is a potential source of toxic cyanobacteria, with water quality parameters such as water temperature, electrical conductivity, total dissolved solids, and phosphate significantly influencing their growth. Hence, it is crucial to monitor and manage these water quality parameters to control the harmful cyanobacterial proliferation in WWTPs. Future research should include additional water quality parameters to gain a more comprehensive understanding of the factors affecting cyanobacterial growth in WWTPs.
Selecting suitable locations to establish a ground solar farm in Trincomalee District in Sri Lanka using GIS
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Senadeera, T. S. M.; Bandara, W. M. J. Y.; Herath, H. M. A.; Ariyawansha, J. M. M. S.; Weerasinghe, V.P.A.
Renewable energy is energy derived from natural sources that are regenerated at a higher rate than consumed. One of the examples of the most effective renewable energy sources is solar energy, which is derived from the sun. Solar energy can be extracted directly or indirectly for human use. With the rapid growth in energy demand, solar energy has led to an increased interest in power generation. In Sri Lanka, solar energy investments have developed rapidly in recent years. The ground solar farm is one of the solar energy harvesting types for electricity generation, especially at the industrial level. Our main focus is to provide an additional power supply to the National Grid of Sri Lanka, and this study focuses on utilising Geographic Information Systems (GIS) to identify suitable areas for establishing a ground solar farm in the Trincomalee District, Sri Lanka. Trincomalee District has a tropical wet and dry climate with high sunlight. According to that Trincomalee District was selected as the study area by considering solar irradiation and by focusing on the cumulative solar power plant capacity in Sri Lanka. According to the literature review, various factors can be useful for selecting locations for a ground solar farm. Land surface temperature, slope, land use, and proximity to roads were selected as criteria for this case study. The separate criterion maps were generated and they were reclassified according to the requirements, and those were used with Analytical Hierarchical Process (AHP) to find the weights for overlay analysis in GIS. The resulting final factor map shows a land area of 24.47 km2 for Trincomalee District as highly suitable for establishing a ground solar farm. This case study aims to reduce the overconsumption of natural resources that are used to produce energy and to ensure the protection of the environment through using renewable energy.