https://ir.kdu.ac.lk/handle/345/5800 2026-04-22T01:20:18Z https://ir.kdu.ac.lk/handle/345/5824 Assessment of Groundwater Quality due to Leachate Generated from a Solid Waste Dumpsite Udamadura, LK; Samarakoon, MB In Sri Lanka, one of the main sources of groundwater pollution is the leachate generated from solid waste dumpsites. Karadiyana landfill is located 2km from Ratmalana airport, which receives nearly 500 tons of Municipal Solid Waste (MSW) daily. There is a considerable number of wells in the surrounding area, which are being used for drinking and other domestic purposes. The main focus of this study was to identify whether there is any effect of leachate on groundwater in nearby areas of Karadiyana dumpsite. Thus, well waters in nearby areas of the Karadiyana Dumpsite were collected. Subsequently, parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Phosphates and Ammoniacal Nitrogen included in these groundwater samples were determined. After the obtained concentrations were compared with permissible standards for drinking water, it was identified that some of the groundwater samples contained several contaminants exceeding the permissible limits. Moreover, the effect of distance on the degree of leachate contamination was also determined. Accordingly, it was suggested to identify the causing grounds for the anomaly obtained in these outcomes. As the conclusion, it was determined that for the time being, there is no significant effect of leachate on groundwater within the area starting from 400m away from the Karadiyana Dumpsite. 2022-09-29T00:00:00Z https://ir.kdu.ac.lk/handle/345/5823 Study of Issues in Sludge Disposal and Management in Wastewater Treatment Plants Anuththara, EMS; Samarakoon, MB Improper methods of treatment, disposal and management of sludge generated by wastewater treatment plants has become a major environmental issue at present. This research focuses on identifying the environmental impact caused by the methods used when disposing and reusing the produced sludge as fertilizer, by the Biyagama CWWTP, Ratmalana/ Moratuwa WWTP, Ja-Ela/ Ekala WWTP and Raddolugama sewerage treatment plant. The sludge samples collected from the dumpsites were tested for heavy metals, nutrients, and organic compounds present in them. After analysing the constituents present in the sludge, the issues in respective treatment plants and its procedures were identified. Moreover, the possibility of using the sludge as construction material, fertilizer and whether it satisfies the requirements to use as a fertilizer for crops cultivated for human consumption were discussed. In addition, a model limitation scale for the sludge standards was introduced through this study after observing various limitations maintained in other international standards. As per the results, only sludge from Raddolugama Plant was assured as safe for land application, and sludge in Biyagama plant was found to be the most suitable for fertilization among the others although other minor hitches were found. Conclusively, eco-friendly and sustainable solutions were suggested to improve the sludge qualities and overcome the issues found and proposed how sludge could be utilized for greater uses without wasting a valuable asset. 2022-09-29T00:00:00Z https://ir.kdu.ac.lk/handle/345/5822 Improving Turbidity Removal Efficiency in Slow Sand Filter during the Occurrence of High Turbidity Levels in Surface Water Anoja, N; Sutharsan, ME; Sarankan, S The prominent drinking water treatment process practised to eliminate turbidity from surface water, especially during high turbidity occurrence in the surface water, is coagulation, sedimentation and rapid sand filtration for many years. However, the possibility of turbidity removal using a slow sand filter (SSF) was not extensively studied in the case of high turbidity occurrence in the surface water. This study aimed to evaluate the performance of SSF in terms of turbidity removal in surface water, when pre-adding poly-aluminium chloride (PACl) as a coagulant chemical along with the pre-treatment by roughing filter. One per cent of PACl is prepared and dosed at the rate of 20 mg/L with raw water into the water intake chamber before it reaches the SSF. The raw and treated water samples were collected every six-hour intervals. The raw water samples whose turbidity level was more than 50 NTU were considered and analysed from 174 number of trails. Turbidity level of raw water and filtered water was observed in the range of 50-313 NTU and 0.31-5.5 NTU respectively. The turbidity of treated water by SSF was observed to be well below the SLS 614-2013 acceptable limit of 2 NTU in 98.8% of the treated samples. It is observed the turbidity removal efficiency increases when the raw water turbidity level increases. The result shows that the turbidity of treated water from SSF was complying with the requirement in 98.5% of the trails, which enable the proper function of the treatment plant during the high raw water turbidity by complying with SLS 614-2013 when adopting this methodology. 2022-09-29T00:00:00Z https://ir.kdu.ac.lk/handle/345/5821 Analysis of the Behavior of Improved Soil under Shallow Concrete Foundations Liyanage, SYW; Sampath, KHSM As a step towards sustainability and environmental protection, use of waste material and by-products in construction activities is becoming a trend. Quarry dust is a waste product of stone crushing process, which can be effectively used as a shallow ground stabilizer. This research investigates the behaviour of improved soil under a shallow foundation, by adding various mix proportions of quarry dust to the natural weak soil. Further, based on the foundation stability analysis, determining an optimum proportion of soil + quarry dust mix is studied. This is done by numerically analysing the displacement, shear strength, stresses, strains, and safety factors of stabilized soil underneath a shallow foundation. The study confirms that mixing quarry dust with natural weak soil - layered under a shallow foundation can significantly improve the stability of the respective foundation. This is due to the improvement of soil shear strength parameters, i.e. cohesion and friction angles, which are used for the stability analysis in the numerical model – incorporating the Mohr-Coulomb failure criterion. Further, it can be concluded that the optimum quarry dust mix proportion that yields the highest factor of safety of the foundation is around 60% - 80%, in which further increase in quarry dust % can cause reduction in the stability, due to unbalanced effect of cohesion and friction angle of mixed soil. Overall, the study concludes that mixing quarry dust with natural weak soil can be considered as a better ground improvement technique; however, the optimum mix proportion has to be determined after a careful analysis of the specific soil types, ground conditions and the applied loads. 2022-09-29T00:00:00Z