Articles
Publication Date: 2026
Renewable Energy (0960-1481)256
This study presents the development of a mathematical model to accurately predict the dynamics of salt and water transport in a batch electrodialysis system used for either NaCl desalination or LiCl brine concentration. The primary aim of the model is to simulate the desalination of high-salinity water under specified current density conditions. The governing equations for the electrodialysis stack and associated tanks were formulated and solved using numerical methods. Model predictions were validated against experimental data, demonstrating high accuracy: the deviation between measured and predicted tank concentrations was within ±2 % for both NaCl and LiCl systems. In addition, the study investigated how initial salt concentration, current density, and flow rate influence system performance. The results show that system efficiency is significantly affected by the initial brine concentration. Increasing the salt concentration from 5 wt% to 10 wt% and 20 wt% reduced desalination efficiencies by approximately 67 % and 93 %, respectively. Moreover, salt flux improved with higher current density, with a 71 % increase in desalination observed when current density was raised from 100 A/m2 to 400 A/m2. © 2025 Elsevier Ltd
The rising demand for sustainable energy solutions has renewed interest in microalgae-based biofuels due to their rapid growth and lipid accumulation capacity. This study investigates the effects of five commonly used culture media (Zarrouk, BG-11, BBM, Bristol, and f/2) and varying nitrogen stress levels on the growth kinetics, lipid content, and fatty acid composition of Spirulina platensis. The experimental design, optimized via Response Surface Methodology (RSM), reveals that Zarrouk medium yielded the highest biomass concentration (2.29 g.L−1) under nitrogen limitation (N/Nbase = 2), while f/2 medium, under the highest nitrogen concentration (N/Nbase = 10), achieved the highest lipid content (37%). Additionally, the f/2 medium promoted the highest accumulation of polyunsaturated fatty acids (PUFAs), including C18:2 and C18:3, enhancing biofuel combustion quality. In contrast, nitrogen-limited media like Zarrouk supported saturated fatty acid (SFA) accumulation, offering better oxidative stability. The study identifies an optimal N/P ratio for balancing biomass production and lipid accumulation, enabling tailored lipid profiles for specific biofuel applications. These findings underscore the importance of nutrient stoichiometry and culture medium selection in maximizing lipid productivity in S. platensis for biodiesel production. This study is distinctive because it simultaneously compares five widely used Spirulina media across a broad nitrogen-stress gradient, quantifies how medium composition and N/P stoichiometry co-determine lipid yield and fatty acid profile within a unified RSM framework, and couples the optimization with a preliminary techno-economic assessment. © 2026 Elsevier B.V.
