http://repository.ou.ac.lk/handle/123456789/4273 2026-10-09T17:05:51Z http://repository.ou.ac.lk/handle/123456789/4298 Macro and Micro-Litter Pollution at Crow Island Beach: Abundance and Composition Wickramasinghe, S. M. S. K.; Kanagaratnam, Reinurshan; Rideevitage, Oshani; Dharmapriya, Thakshila Nadeeshani; Vithanage, Meththika; Rajapaksha, Anushka Upamali Marine litter pollution has become an increasing environmental concern worldwide. The coastal regions near major river mouths are highly vulnerable to accumulation of litter. Crow Island Beach is located at the mouth of the Kelani River, Sri Lanka, one of the major rivers in Sri Lanka, which is the source of water for the capital, however, has no comprehensive scientific data on source identification, litter abundance, composition, and pollution status. This study was conducted in January, February, and May 2026 across 10 sampling locations along the beach to assess the pollution level at the beach. 2.5 m2 quadrat was used to collect macro-litter samples, and FTIR spectroscopy was used to perform polymer identification. To evaluate the overall pollution status of the beach, the Clean Coast Index (CCI) and Pollution Load Index (PLI) were calculated. Results indicated that domestic and household waste was the dominant source of macro-litter, and the most abundant identified polymer types were HDPE and PP. The 0.5- 5 cm range plastic debris category represented the largest proportion of collected litter, suggesting extensive fragmentation of macro-litter due to prolonged weathering. Spatial analysis was used to identify persistent litter accumulation hotspots, particularly near major accumulation areas influenced by riverine inflows. The calculated CCI value of 180.8 and PLI value of 2.2 indicated a highly polluted coastal environment. Field observations identified clinically related waste, including syringes and blood collection tubes. Increased litter accumulation during periods of rainfall and high-water levels suggest that riverine transport may contribute to litter accumulation. This study contributes quantitative baseline data on macro- litter abundance, polymer composition, and pollution indices for the coastal region of Colombo. 2026-01-01T00:00:00Z http://repository.ou.ac.lk/handle/123456789/4297 Design and Evaluation of a Biochar-Integrated Supramolecular Fibrous Framework for Efficient Microplastics Removal from Aqueous Environments Kanchanamala, L. Sanduni; Rajapaksha, Anushka Upamali; Premarathna, K.S.D.; Wijesekara, Hasintha; Vithanage, Meththika; Khan, Alam Current wastewater treatment plants are unable to capture the microplastics (MPs), highlighting the need for sustainable, low-cost, and eco-friendly remediation methods. This study focuses on the design of supramolecular fibrous frameworks produced via the self-assembly of chitin (Ct) and cellulose (Cel) fibers, combined with municipal solid waste (MSW) derived biochar (BC), for MP removal. MSW-BC was prepared via the pyrolysis at 550 °C. Ct was dispersed in 5% acetic acid and combined with Cel and BC at a 10:1:1 ratio. All three components were combined and homogenized for 30 min. Following blending, the mixture was frozen at −19 °C for 24 h. The frozen mixture was oven-dried at 70 °C for 72 h. Fourier transform infrared (FTIR) spectroscopy confirmed successful integration of the three components, revealing characteristic O–H/N–H stretching (3300-3250 cm−1), C–H stretching (2890 cm−1), amide I and II bands (1650-1625 cm−1 and 1550 cm−1), and C–O–C/C–O stretching vibrations (1157 and 1010 cm−1), indicative of strong hydrogen bonding and intermolecular interactions between the biopolymer matrix and BC surface. MP removal performance was assessed on packed-bed column experiments using a 50 mL polyethylene (PE) MP solution (1 mg/L). Under optimum conditions (10 cm bed height, 2.5 mL/min flow rate), the quartz-only control removed 42.14% of MPs, while the quartz/Ct-Cel-BC column achieved 95.30% removal. Therefore, incorporating BC may have improved physical entrapment due to its porous structure and fibrous framework. Removal efficiency increased with greater bed height and lower flow rate, which may be due to longer residence times and greater contact time between MPs and the adsorbent surface. Overall, the integration of MSW-BC into a Ct-Cel supramolecular fibrous framework yielded a multifunctional, cost-effective adsorbent with excellent PE MP removal efficiency. 2026-01-01T00:00:00Z http://repository.ou.ac.lk/handle/123456789/4296 Waste-Derived Nitrogen-Doped Biochar for Persulfate Activation and Bisphenol A Degradation Imbulana, K.A.S.S.; Manangodage, Chathumi; Soysa, H. S. M.; Premarathna, K.S.D.; Rajapaksha, Anushka Upamali; Vithanage, Meththika Plastic waste constitutes a major environmental concern within municipal solid waste management systems. Its progressive degradation and weathering facilitate the leaching of hazardous additives, notably bisphenol A (BPA), a well-documented endocrine-disrupting compound with significant toxicological effects for aquatic ecosystems and human health. The aim of this study was to use municipal solid waste (MSW) compost residue biomass, including coconut shell, coconut husk, and wood fractions, to prepare nitrogen- doped biochar (N-MSW-BC) for persulfate (PS)- mediated catalytic degradation of BPA. The biomass was pyrolyzed in the presence of urea and sodium bicarbonate. The physicochemical properties of N-MSW-BC were assessed using proximate analysis, point of zero charge (pHpzc), and Fourier transform infrared (FTIR) spectroscopy. The potential of BPA degradation by N-MSW-BC was evaluated through adsorption experiments, pre-adsorption kinetics, and synchronous degradation studies. FTIR verified the integration of nitrogen-containing heterocycles into the carbon matrix, which showed distinctive bands near 3660–3280 cm−1 (O-H/N-H stretching) and at 1594 cm−1, attributed to overlapping aromatic C=C and C=N stretching and N-H bending vibrations. A stable carbon content of 41.83% was determined by proximate analysis, suggesting a graphitic-rich carbon matrix ideal for PS activation. BPA removal remained consistently high (~99.7%) across a pH range of 2-9 in a pH-edge experiment with the N- MSW-BC persulfate (10 mM) system. At 180 min, pre-adsorption followed by PS activation achieved 99.5% BPA elimination; whereas, the synchronous system only achieved 90.5% within the same exposure period. The electrostatic forces with BPA and biochar were influenced by their pHpzc (~ 8.2). These findings suggest an interfacial, adsorption- mediated catalytic process, establishing N-MSW- BC generated from compost residues as a sustainable material for BPA remediation by persulfate activation. 2026-01-01T00:00:00Z http://repository.ou.ac.lk/handle/123456789/4295 Assessment of Microplastic Pollution in the Kelani and Gin River Drinking Water Intake Points in Sri Lanka Lahiru Shanaka, K.G.; Aththanayaka, D.R.S.S.; Siriwardana, R.P.C.P.; Samarasekara, R.S.M.; Dissanayake, D.M.M.R. Microplastic pollution has become a growing concern in freshwater systems that supply drinking water. This study used a quantitative experimental design to assess the occurrence and preliminary characteristics of microplastics in the Kelani and Gin River drinking-water intake points in Sri Lanka. Water and surface sediment samples were collected from upstream, intake, and downstream locations, then processed by filtration, density separation, and phase-contrast microscopy. The observed particles were classified into four main morphologies: fibers, fragments, films, and pellets. In the reported counts, Kelani River water contained 48 fibers, 32 fragments, 25 films, and 34 pellets, while Gin River water contained 39 fibers, 34 fragments, 21 films, and 32 pellets; sediment samples showed lower overall counts but the same dominant morphologies. XRD was used only as a preliminary structural characterization technique; definitive polymer identification requires complementary techniques such as FTIR and SEM, which were not performed in the present study. The study provides baseline evidence of suspected microplastic contamination at both drinking-water intake systems and supports continued monitoring and further polymer-specific characterization in Sri Lanka’s drinking-water sources. 2026-01-01T00:00:00Z