Research Publications
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Publication Open Access Valorization of Canteen Wastewater Through Optimized Spirulina Platensis Cultivation for Enhanced Carotenoid Production and Nutrient Removal(Multidisciplinary Digital Publishing Institute (MDPI), 2026-01-14) Dodangodage, C. A; Gamage, G.N; Wijesekara, I.A; Kasturiarachchi, J.C; Perera, T.A; Rajapakshe, D; Halwatura, R.UThe valorization of nutrient-rich institutional effluents represents a promising route for sustainable algal biotechnology. This study investigates the potential of canteen wastewater (CW) as an alternative culture medium for Spirulina platensis, integrating wastewater treatment with high-value carotenoid and lipid production. Growth performance, biochemical composition, and nutrient removal efficiencies were systematically evaluated in 2 L photobioreactors under optimized conditions. Spirulina cultured in 75% CW under 180 μmol photons m−2 s−1 achieved a biomass productivity of 0.071 g L−1 day−1, nearly three-fold higher than the synthetic BG-11 control (0.023 g L−1 day−1). Nutrient remediation was highly efficient, with 92.12% nitrate and 90.05% phosphate removal, effectively reducing effluent concentrations below discharge limits. Biochemical profiling revealed that wastewater-grown biomass contained 54.3% protein and 7.85% lipids, with a remarkable carotenoid yield of 21.81 mg g−1 DW—significantly higher than the control (6.85 mg g−1 DW). Mechanistic analysis suggests that the balanced nutrient stoichiometry (C:N:P ≈ 30:4:1) and mixotrophic conditions enhanced biomass quality while mitigating ammonia toxicity. This study demonstrates the first integrated application of canteen wastewater for dual-purpose bioremediation and pigment-rich biomass production, establishing a scalable circular bioeconomy framework for institutional waste management.Publication Open Access Production of Carbohydrate-Rich Chlorella sp. Biomass Using Clarified Aquaponics Effluent for Bioethanol Feedstock Applications(Multidisciplinary Digital Publishing Institute (MDPI), 2026-03-26) Dodangodage, C. A; Gamage, G. N; Mallawa, L.C; Kasturiarachchi, J.C; Fernando, K. V; Halwatura, R.H; Perera, T.A; Rajapakshe, S.D; Niyangoda, S.S; Halwatura, R.UThe integration of microalgal cultivation with wastewater streams offers a promising pathway to enhance resource efficiency within circular bioeconomy frameworks. However, the suitability of clarified aquaponics sedimentation effluent for producing carbohydrate-rich microalgal biomass remains insufficiently evaluated, particularly with respect to nutrient recovery and bioethanol-relevant feedstock potential. In this study, clarified aquaponics sedimentation effluent was assessed as a cultivation medium for Chlorella sp. under controlled laboratory conditions. Biomass productivity, nutrient removal performance, and carbohydrate accumulation were systematically evaluated and compared with conventional synthetic medium. Chlorella sp. cultivated in clarified aquaponic effluent achieved a maximum biomass concentration of approximately 2.05 g L−1, exceeding that obtained in Bold’s Basal Medium. Carbohydrate content exceeded 40% of dry weight, indicating suitability for fermentable sugar production. Nitrate and phosphate removal efficiencies greater than 95% were achieved, with mass balance analysis confirming biological assimilation as the primary removal mechanism (~87.4%). This confirms the dual functionality of the system. The effective nutrient assimilation and confirmed the dual functionality of the system as both a biomass production and nutrient recovery process. Comparable performance under diluted and undiluted effluent conditions further indicated that freshwater dilution is not required following clarification. Light saturation was observed at 180–190 μmol m−2 s−1, providing guidance for energy-efficient operation. These findings demonstrate that clarified aquaponics effluent can serve as an effective alternative growth medium for producing carbohydrate-rich Chlorella sp. biomass while enabling nutrient recovery. The estimated bioethanol potential is theoretical, based on stoichiometric conversion assumptions, and experimental fermentation was not conducted. This work provides quantitative evidence supporting the integration of microalgae into aquaponic systems and establishes a foundation for future pilot-scale, techno-economic, and life-cycle assessments.Publication Open Access Circular Valorization of Post-Industrial Textile Waste in Thermal-Insulating Cementitious Ceiling Sheets(Multidisciplinary Digital Publishing Institute (MDPI), 2026-02-27) Fernando, K. V; Dodangodage, C.A; Seneviratne, V.M; Jayasinghe, S.M; Dharmaratne, D.D; Gamage, G.N; Halwatura, R. H; Gunasekera U.S.W; Halwatura, R.UThe construction sector faces increasing pressure to reduce the embodied energy of building materials while valorizing industrial waste streams. This study evaluates the direct incorporation of post-industrial textile waste (100% cotton and cotton–polyester blends) in its native form to develop high-performance cementitious ceiling sheets. Composites were fabricated under a controlled hydraulic compaction pressure of 2.0 MPa, optimized to achieve matrix densification while preserving the integrity of the fibrous network. Viscoelastic recovery of the compressed fibers induced a hierarchical double-porosity architecture characterized by macro-voids and hollow fiber lumens. This microstructural evolution reduced thermal conductivity to 0.091 W/m·K, approximately 50% lower than commercial cement–fiber benchmarks—without compromising mechanical compliance. Scanning Electron Microscopy (SEM) revealed a mechanistic decoupling between water absorption and dimensional stability. Although the CP15 formulation (15 wt.% cotton–polyester) exhibited high moisture uptake (~21%), thickness swelling remained limited to 1.35%. This dimensional stability is attributed to the hydrophobic polyester framework, which bridges microcracks and constrains hygroscopic expansion within the cellulosic phase. The optimized CP15 composite achieved a Modulus of Rupture (MOR) of 8.75 MPa, exceeding ISO 8336 Category C, Class 2 requirements. Despite increased thickness, the areal density (10.84 kg/m2) remains compatible with standard gypsum-grade suspension systems, eliminating the need for structural modification. These findings establish a scalable, direct-valorization strategy for circular construction materials delivering enhanced thermal insulation and robust performance under tropical climatic conditions.Publication Embargo Reinforced Fiber Polymer Composite with Palmyra Fiber and Waste Polythene(SLIIT, Faculty of Engineering, 2024-10) Galagedara, R.Y; Gangabadaarachchi, S.N; Halwatura, R.UNatural fiber, a preferable replacement, is the most commonly used fiber in the composites industry. Most businesses employ natural fibers since they are equipped with a sustainability value and are increasingly evaluated as reinforcement for polymer-matrix composites. This study attempts to use thermoplastic/Palmyra fiber composites in the construction industry specifically in ceiling and wall panels. Before starting the material development process and applications for this fiber, it is important to consider the physical and mechanical properties of Palmyra fibers. Testing was conducted to determine the fiber's diameter, density, water absorption, and tensile strength. The density and diameter of Palmyra fiber were determined using the psychometric method and an optical microscope, respectively. An electronic tensometer was used to measure Young's modulus and tensile strength of the Palmyra fiber. The average diameter and density of Palmyra fibers were obtained as 523.01 μm and 0.88 g/cm3, and the fiber’s Young's modulus and ultimate tensile strength were 53.94 MPa and 6.15 GPa, respectively. The 2.5 mm and 3.2 mm thick composite sheets were produced using a hot press machine, varying Palmyra fiber weight, and an applicable polymer matrix. Tensile and bending tests were attained to evaluate the mechanical characteristics of the composite material at this stage. ASTM D3039 and ASTM D790 were followed for testing the composite properties. When the Palmyra weight fraction varied from 10% of the total weight, the maximum tensile strength and the maximum bending strength were 14.778 N/mm2 and 19.478 N/mm2, respectively. The relevant mechanical properties differ from those of commercially available materials.