Research Publications

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Now showing 1 - 10 of 16

Embargo
Brewing plastics: OCT reveals microplastic release from nylon tea bags in simulated brewed tea infusions
(Royal Society of Chemistry, 2026-02-12) Jayasekara, P.M; Abhishek, P; Kahandawala,B.S; Damith, N; Weerasinghe, M; Kahatapitiya, N.S; Silva, B.N; Karunaratne, S; Wijesinghe, R.E; Wijenayake, U
The release of microplastics (MPs) from nylon tea bags poses a critical concern for human exposure; however,their detection and quantification remain challenging especially in beverage matrices, and hence, this study pioneers the use of high-resolution optical coherence tomography (OCT) integrated with an image processing algorithm to rapidly detect and quantify the size and count of the MPs directly in the water extractions simulating tea brewing. The water extractions prepared by simulating tea brewing conditions, hot (100 °C, 1–5min), cold (2 °C, 1 h), and ambient (30 °C, 1 h), were observed employing OCT imaging and validated through Nile Red (NR) staining and digital microscopy. The nylon tea bags steeped in hot water for 5 minutes released 16 000 to 24 000 LMPs (>30 mm) and SMPs (12–30 mm) per millilitre. The estimated daily intake (EDI) of MPs indicates a higher exposure for children (ranging from 0.201 to 0.349 mm3 kg−1 day−1 ) compared to adults (0.046 to 0.080 mm3 kg−1 day−1 ). In contrast, cold brewing for 1 hour released fewer LMPs but an equal quantity of small MPs (SMPs) compared to hot brewing. This OCT-based approach offers a rapid, versatile platform for the detection and quantification of MPs from diverse packaging materials and provides a powerful tool for comprehensive risk assessment when combined with chemical and toxicological analyses.
Embargo
The Current Status, Challenges, and Future Directions of Sustainability Assessment of Buildings in Sri Lanka
(SLIIT, Faculty of Engineering, 2024-10) Herath, M. R; Karunaratne, S
Buildings are currently responsible for 39% of global energy-related carbon emissions; 28% from operational emissions, and 11% from materials and constructions. Sustainability assessments of buildings to estimate the impacts become important for Sri Lanka to meet the national target of achieving socially inclusive, environmentally sustainable, and carbon-neutral housing by 2050. Life Cycle Assessment (LCA) is a powerful tool, which can be used to assess building sustainability. Hence a study was conducted to identify the current status, the challenges faced, and future suggestions for the sustainability assessments of buildings in Sri Lanka. A questionnaire survey was conducted to collect data among building construction professionals in Sri Lanka where 55%, 17.5%, 10%, 9.2%, and 8.3% were civil engineers, engineering consultants, quantity surveyors, academics, and architects out of 120 total respondents. More than half of the respondents, 52% have more than 15 years of building construction experience, and the rest 48% have experienced less than 15 years. The questionnaire consisted of 45 questions with three main segments to capture the respondents' experience in building sustainable assessment, its application, and the challenges faced in the attempt. According to the analysis, it was evident that there was a lack of performing sustainability assessments in Sri Lanka as only 15.8% of total respondents have experience in performing sustainability assessments of buildings, although more than 65% have moderate to expert knowledge in LCA. The reasons such as lack of policies and regulations and lack of knowledge and experience were the main causes for sustainability assessment not being popular within the industry. Sustainability assessment is important in benchmarking projects, reducing the emissions from the building sector while achieving nationally determined contributions by 2050.
Open Access
Comparative Lifecycle Analysis of Sri Lankan Non-Conventional Roofing Materials
(SLIIT, Faculty of Engineering, 2023-10) Fernando, W.A.N; Karunaratne, S
Building materials, especially roofing products, play a major role as they are essential for any building construction. Knowledge of the environmental performance of building materials is vital when building life cycle assessment. However, only a few studies have been conducted in Sri Lanka in this regard. The present study focuses on the environmental life cycle assessment of two different nonconventional roofing materials used in Sri Lanka. Acrylonitrile Styrene Acrylate roofing sheets and Calicut-type clay roofing tiles have been selected for the study. In order to measure and calculate environmental impacts of both types of roofing materials, field data was collected quantitatively and noted as per ISO14040 and ISO14044. Using the Cradle-to-Gate LCA technique and OpenLCA software, the environmental impacts as midpoint and endpoint categories were evaluated. As the main output of the study, environmental performance of these two roofing materials were compared, the hotspots of the manufacturing process and the causes were also identified. . Accordingly, the global warming potential of Acrylonitrile Styrene Acrylate roofing sheets and Calicut-type clay roofing tiles is 13.5 kgs of CO2 eq. and 8.95 kgs of CO2 eq. respectively. Further, comparison of the endpoint categories showed the resource depletion was most impactful, indicating 0.814012 points and0.65305 points, respectively for the two roofing material types. Further, kiln firing was identified as the environmental hotspot contributing most to the endpoint and midpoint impact categories for clay roofing tiles, while mixing materials by hot mixer was the hotspot for Acrylonitrile Styrene Acrylate roofing sheets. In addition, the overall results demonstrated how the production process of clay tile influences more than the Acrylonitrile Styrene Acrylate roofing sheet on both the midpoint as well as the endpoint impact categories.
Open Access
Achieving near-zero carbon dioxide emissions from energy use: The case of Sri Lanka
(Elsevier, 2023-07-04) Fernando, G.L; Liyanage, M.H; Anandarajah, G; Attalage, R. A; Karunaratne, S
Signatories to the Paris Agreement are to achieve net zero Green House Gas (GHG) emissions during the half-century to pursue the efforts limiting global average temperature increase by 2 °C compared to pre-industrial levels. This study models ambitious to challenging scenarios involving energy demand and supply side actions for energy system transition toward net-zero for Sri Lanka. To analyze these scenarios a least cost optimization-based bottom-up type energy system model was developed from 2015 to 2050. A Business-as-usual (BAU) scenario and four countermeasure (CM) scenarios termed Plausible, Ambitious, Challenging, and Stringent were developed. Four different carbon tax rates were used to fathom the level of carbon tax needed to achieve net-zero emissions. The CM scenarios were formulated considering different technology options and policy measures such as the diffusion of efficient technologies, availability of renewable energy sources, use of cleaner fuels, the introduction of nuclear and carbon capture and storage technologies, and green hydrogen for power generation. The result of this study reveals that the stringent scenario which includes aggressive policy measures in both the energy supply and demand sectors, such as nuclear, and renewable energy for power generation, diffusion of efficient Enduse devices, fuel switching, including the introduction of electric cars, and increased share for public transport achieves the near carbon-neutral scenario at a carbon tax trajectory of 32 US$/tCO2 in 2020 and 562US$/tCO2 in 2050. The Net Energy Import Dependency (NEID) of the country decreases to 13 % in 2050 compared to that of the BAU scenario (65 %) under the near carbon neutral scenario, which is a positive sign from the energy security perspective.
Embargo
The use of plastic aggregate in concrete
(IEEE, 2022-10-04) Karunaratne, S; Zahra Ameen, C. A
Plastic waste management is a growing concern worldwide since permanent solutions are costly for third-world countries. This study explores storing plastic waste in concrete as a partial replacement of the fine aggregate to produce a useful building material. To resolve the material's lack of compressive strength, this study used HDPE chemically treated with Sodium Hypochlorite (NaOCl) and partially replaced the cement with silica fume at 7.5%, and 10% to improve the concretes Interfacial Transition Zones (ITZ). This research tests the workability, density, and compressive strength, and completes a microstructure analysis of this material to determine if structural lightweight concrete (SLWC) can be produced. The results obtained indicate that adding silica fume with chemically treated aggregate increased the compressive strength by 1.9% and 7.4% respectively in comparison to the control. Through the statistical analysis, these additions were then shown to make a significant difference in the concrete's strength. The microstructure analysis too confirmed that the quality of the ITZs had improved in these mixtures. However, the workability of these 2 mixtures was reduced by 77.4%. The study concludes that although the concrete isn't lightweight, its compressive strength can be improved to match that of conventional structural concrete.
Embargo
A review of comprehensiveness, user-friendliness, and contribution for sustainable design of whole building environmental life cycle assessment software tools
(Elsevier, 2022-03-15) Karunaratne, S; Dharmarathna, D
Whole building environmental life cycle impact assessment enables to both construct and operate buildings with least impacts while optimizing resource efficiency and conservation. This study aims to, (1) develop a detailed criteria based on selected thematic areas and associated focus areas, to evaluate the key attributes of whole building environmental life cycle assessment software tools (WBELCA-STs), (2) analyze the distinctive abilities and areas for improvement of the selected software tools (STs) with respect to the key attributes, (3) categorize the selected STs according to their individual performances to facilitate ST selection, to match the user requirements. WBELCA-STs currently used were identified by reviewing published scientific literature (2001–2021). Nine STs were shortlisted based on the number of results returned during the literature search. A comprehensive evaluation criterion based on five themes was developed and shortlisted nine STs were evaluated against the key attributes. This study adds to the existing knowledge on whole building environmental life cycle assessment by identifying the key areas that strengthen the comprehensiveness and user-friendliness of WBELCA-STs, while promoting sustainable design in all life cycle stages. Further the strengths and areas for improvement of the STs were identified to categorize them. Priorities needed to be considered in selecting a suitable ST for building assessment projects were revealed. There is a need in developing, maintaining and updating more databases and STs to popularize building environmental sustainability assessments in many regions of the world, including Asia.
Open Access
Global warming potential of English brick manufacturing in Sri Lanka: A cradle to gate analysis
(IEEE, 2021-07-27) Herath, I; Karunaratne, S; Dharmarathna, D
Clay bricks are one of the most commonly used walling materials in Sri Lanka. The brick manufacturing process poses a notable impact on the environment. Clay excavation leads to resource depletion while diesel fuel utilized for excavation and clay transportation pollutes the air. Additionally, tree cutting for wood fuel contributes to deforestation whilst wood burning promotes air pollution. Thus, this research aimed to quantify the global warming potential due to English brick manufacturing using cradle to gate Life Cycle Assessment (LCA) approach. The functional unit used was one-meter square of the brick wall area. Data collection, analysis and interpretation of results were done by the ISO 14044/14040 standards. Primary life cycle inventory data was gathered via brick kiln owners and workers. The LCA assembly was modelled using the ‘OpenLCA’ software. Three product systems were defined according to the brick bond types and wall thicknesses. The global warming potential related to brick production was assessed using the ‘GWP 100a’ method. Clay excavation, clay transportation and wood chamber firing emerged as emission hotspots. The study revealed that the global warming potential of 225mm brick wall and 115mm brick wall as 11.9 and 5.9 kg CO2-eq/m 2 , respectively. Through this study, local clay brick industry can be driven to improve the overall sustainability of the brick manufacturing sector.
Open Access
Estimation of drag coefficient of trees considering the tree bending or overturning situations
(Faculty of Engineering - University Of Ruhuna. Galle, 2012) Morinaga, T; Tanaka, N; Yagisawa, J; Karunaratne, S; Weerakoon, W. M. S. B
Drag coefficients of a real tree trunk and the sheltering effects of an upstream trunk on a downstream one in a linear arrangement with different spacings and inclinations were investigated in detail. In addition, for elucidating the change of drag coefficient for an overturned tree, drag force acting on a real tree with roots was also measured in this study. For the measurement of drag force with different inclinations, Terminalia Cattapa and Albizia sp., vegetated in Sri Lanka, were selected in this study. Drag coefficient of inclined tree trunk has the similar tendency in relation to the Reynolds number with that of vertical standing tree investigated in Tanaka et al.(2011). For the vertical tree trunk with rough surface, drag coefficient of rear-side tree trunk was decreased with decreasing L/d (where, L is spacing and d is the diameter of trunk). In addition, as a result of mutual interference experiment of two inclined tree trunk, the drag coefficient of rear-side trunk decreased with the increase of the inclination. Under the influence of the increment of projected area due to existence of roots and shear force acting on tree trunk surface, the drag coefficient of a tree with roots became similar value (1.0-1.2) comparing with that of a vertical standing tree.
Open Access
Colour-based estimation of rhizome age in Phragmites australis
(Kluwer Academic Publishers, 2004-10) Karunaratne, S; Asaeda, T; Toyooka, S
The colour of different age groups of Phragmites australis (Cav.) Trin. ex Steudel rhizomes was studied from April through October 2000 at approximately one-month intervals to propose a more efficient method to identify the rhizome age based on the Munsell colour-order system. Seven rhizome age-classes were recognized, from <1 to 6 years old, based on descriptions published in the scientific literature. During April and May sampling, spectral reflectance between 400 and 700 nm of different rhizome ages was measured at 10 nm intervals, using a spectral colorimeter. Rhizomes of different ages were assigned colours by selecting one/two shortest Euclidian distances between the mean spectral reflectance of each rhizome age category and the Munsell colours on the four-dimentional subspace, made by Principal Component Analysis of the spectral reflectance data of 1289 Munsell colours. The Munsell colour for new to six-year-old rhizomes changed from yellow to yellow-red, and the value decreased from new to six-year-old rhizomes, indicating a darkening with ageing. The age of rhizomes collected from April through October was estimated using the colour key, in addition to the age attribution based on branching hierarchy. Between 87% and 100% of the rhizomes attributed to a certain age class based on branching hierarchy were assigned to the same age class using colours during all sampling dates. There was a strong correlation (r = +0.96) between rhizome age estimated by branching hierarchy and colour. At each sampling, bulk density, an indicator of rhizome storage levels, measured as a verification of age identification, varied among the age categories indicating distinct differences in storage levels. These results confirmed that rhizomes of a specific age category could be assigned a distinct colour, which remains more or less unchanged throughout the growing season. Thus, colour can be used as a primary criterion in the estimation of the age of P. australis rhizomes.
Embargo
Mathematical modeling as a tool in aquatic ecosystem management
(American Society of Civil Engineers, 2002-04) Karunaratne, S; Asaeda, T
The capacity of an existing model to simulate the growth (biomass) of a reed [Phragmites australis (Cav) Trin. ex Stuedel] in fresh water habitats using published field data and the incorporation of a submodel to estimate seasonal variation in reed mineral–nutrient content was investigated. This new feature also enabled one to estimate plant removal of mineral–nutrients from sediments. Model-predicted and observed shoot, rhizome, and root biomass showed concordance correlation coefficients of 0.97, 0.52, and 0.99, respectively. The nutrient analysis study showed that the annual uptakes of nitrogen and phosphorus from sediment by P. australis in the Denmark Vejlerne Nature Reserve were 143.9 and 16.1 kg ha−1, respectively. The simulated results also showed that at the time of peak standing stock of minerals, shoots contained 40 and 22.5% of whole plant N and P, respectively. This suggested that the use of the common reed in wastewater treatment plants allows removal of nitrogen more easily than phosphorus, because a higher percentage of nitrogen is bound with the easily removable shoot parts.

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