Browsing by Author "Rajapakshe, D"

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From AI Assistance to Critical Thinking: Exploring Cognitive Offloading and Metacognition as Mechanisms within Personalized Learning Environments
(Institute of Electrical and Electronics Engineers Inc., 2026) Gunathilake, N; Gamage, A; Rajapakshe, D; Jayasooriya, M; Wisenthige, K; Yapa, C.G
The rapid adoption of AI-assisted learning tools in higher education has completely transformed the undergraduate study system, but empirical evidence on their impact on deep cognition and learning processes is limited. This study investigates the effects of AI-assisted learning tool usage on metacognition, cognitive offloading, personalized learning, and critical thinking among Sri Lankan undergraduates. Using positivism philosophy and a deductive quantitative approach, data were collected from 379 students in computing, management, and engineering subjects through a 35-items, five-point Likert scale questionnaire, and analyzed using PLS-SEM. The findings reveal significant direct, indirect, and moderating relationships among key variables, suggesting that the use of AI-assisted learning tools influences students’ learning regulation, reliance on external support, and development of higher-order thinking. This study provides empirical evidence for the cognitive and psychological effects of AI-assisted learning tools, and helps address an important research gap, and offers practical insights for educators, curriculum developers, and policymakers to use balanced and effective AI integration in higher education.
Open Access
Integrated Microalgal–Aquaponic Systems for Enhanced Water Treatment and Food Security: A Critical Review of Recent Advances in Process Integration and Resource Recovery
(Multidisciplinary Digital Publishing Institute (MDPI), 2026-01-12) Dodangodage, C.A; Kasturiarachchi, J. C; Wijesekara, I. A; Perera, T.A; Rajapakshe, D; Halwatura, R
The convergence of food insecurity, water scarcity, and environmental degradation has intensified the global search for sustainable agricultural models. Integrated Microalgal– Aquaponic Systems (IAMS) have emerged as a novel multi-trophic platform that unites aquaculture, hydroponics, and microalgal cultivation into a closed-loop framework for resource-efficient food production and water recovery. This critical review synthesizes empirical findings and engineering advancements published between 2008 and 2024, evaluating IAMS performance relative to traditional agriculture and recirculating aquaculture systems (RAS). Reported under controlled laboratory and pilot-scale conditions, IAMS have achieved nitrogen and phosphorus recovery efficiencies exceeding 95% while potentially reducing water consumption by up to 90% compared to conventional farming. The integration of microalgal photobioreactors enhances nutrient retention, may contribute to internal carbon capture, and enables the generation of diversified co-products, including biofertilizers and protein-rich aquafeeds. Nevertheless, significant barriers to commercial scalability persist, including the biological complexity of maintaining multi-trophic synchrony, high initial capital expenditure (CAPEX), and regulatory ambiguity regarding the safety of waste-derived algal biomass. Technical challenges such as photobioreactor upscaling, biofouling control, and energy optimization are critically discussed. Finally, the review evaluates the alignment of IAMS with UN Sustainable Development Goals 2, 6, and 13, and outlines future research priorities in techno-economic modeling, automation, and policy development to facilitate the transition of IAMS from pilot-scale innovations to viable industrial solutions.
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.U
The 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.