New trends and future prospects for small capacity systems of Renewable Energy-driven DESalination (REDES) are reviewed and assessed in this paper over a nominal desalination capacity range of 3–1000 m³/d. A thorough literature review is reported in order to evaluate current research and developing activities. Outstanding commercial prospects in the near future are identified for two off-grid REDES technologies under development. First, wave energy converters with direct coupling to seawater desalination. Second, solar micro gas turbines with biofuel backup coupled to reverse osmosis (RO) desalination and/or zero liquid discharge water treatment. These systems, as well as mature REDES plants (namely PV/RO and wind turbines/RO), will benefit from forthcoming advances in energy efficiency in the RO process itself. The Closed Circuit RO desalination (CCRO^TM) concept may be a key configuration for enhancing RE-driven RO desalination. Additionally, opportunities for innovation in seawater RO desalination with variable power consumption are highlighted. On the other hand, our conclusions highlight opportunities for developing novel portable REDES systems based on solar membrane distillation with a portable linear Fresnel concentrator manufactured by SOLATOM. Additionally, the concept of portable systems could foster the commercial development of microbial desalination cells combined with solar PV energy and RO powered by tidal currents.

This work presents a performance assessment of three seawater reverse osmosis—pressure-retarded osmosis (SWRO-PRO) hybrid schemes for energy consumption reduction in seawater desalination applications by using an external low salinity water source. For comparison purposes, another arrangement based on the conventional SWRO process combined with brackish water RO (BWRO) and desalination was analyzed. Reverse osmosis system analysis software environments were used to select the best SWRO configuration and operating conditions. A purposely developed model was used to evaluate the PRO system. Two different cases were assessed depending on the origin of the external low-salinity resource for the PRO process: industrial wastewater and urban treated wastewater. In the case of the industrial wastewater, due to regulations on wastewater reclamation, the best arrangement would be the first SWRO-PRO scheme which was analyzed with a specific energy consumption of 1.54 kWh/m³. If urban treated wastewater is available as an external resource, the results obtained show that this scheme, leading to the minimum specific energy consumption of 1.46 kWh/m³, is the conventional SWRO combined with BWRO. Therefore, hybrid SWRO-PRO systems are recommended to reduce the specific energy consumption of seawater desalination if an industrial wastewater source with low osmotic pressure is available.

In the field of desalination powered by renewable energies, the use of solar power cycles exhibits some favorable characteristics, such as the possibility of implementing thermal energy storage systems or a multi-generation scheme (e.g., electricity, water, cooling, hydrogen). This article presents a review of the latest design proposals in which two power cycles of great potential are considered: the organic Rankine cycle and the supercritical CO₂ power cycle, the latter of growing interest in recent years. The designs found in the literature are grouped into three main types of systems. In the case of solar ORC-based systems, the option of reverse osmosis as a desalination technology is considered in medium-temperature solar systems with storage but also with low-temperature using solar ponds. In the first case, it is also common to incorporate single-effect absorption systems for cooling production. The use of thermal desalination processes is also found in many proposals based on solar ORC. In this case, the usual configuration implies the cycle’s cooling by the own desalination process. This option is also common in systems based on the supercritical CO₂ power cycle where MED technology is usually selected. Designs proposals are reviewed and assessed to point out design recommendations.

This study investigated the use of functionalized cabuya fibers (FCF) as an effective adsorbent for Hg (II) removal from aqueous solutions. The composition, surface properties, and morphology of the FCF were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and Fourier transform infrared spectroscopy (FTIR). The effects of the pH, contact time, temperature, adsorbent dosage, and initial Hg (II) concentration on the adsorption process were studied. Under optimized experimental conditions, FCF achieved a removal efficiency exceeding 92%, with a maximum adsorption capacity of 8.29 mg/g. The experimental data for the FCF isotherm were analyzed using the Langmuir, Freundlich, DR, and Temkin adsorption models. Notably, the Langmuir isotherm exhibited the highest R² value of 0.99, indicating the model’s strong applicability. The pseudo-second-order kinetic model k₂ = 0.42 mg/g.min was employed to elucidate the adsorption mechanism. Thermodynamic studies of the adsorbent FCF were conducted, and ΔG° (-6.16 kJ/mol), ΔH° (36.29 kJ/mol), and ΔS° (141.98 kJ/mol·K) were calculated, assessing the feasibility of the process. Additionally, the desorption results of FCF were evaluated, demonstrating that it can be reused for up to three cycles, achieving adsorption rates of 74% and 62% in the third cycle. This indicates its stability and recycling capacity. Finally, the effectiveness of the FCF was demonstrated by eliminating approximately 91% of Hg (II) from real mineral water samples in Ecuador. These results highlight the p of FCF as promising, eco-friendly, and sustainable adsorbents for the remediation of Hg (II) contamination in aquatic systems.

This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine and a bottoming desalination unit. To assess this system, a design model is developed to select the main design parameters for two different desalination technologies, reverse osmosis and multi-effect distillation, aiming to exploit the available electricity and waste heat from the turbine respectively. The results show that, from a thermodynamic standpoint, it is possible to exceed 65% solar energy utilization if both electricity and waste heat are used to produce fresh water. Nevertheless, the better thermodynamic performance of the fully integrated system does not translate into a more economical production of water. Indeed, the cost of water turns out lower when coupling the solar microturbine and reverse osmosis units only (between 3 and 3.5 Euro/m³), whilst making further use the available waste heat in a multi effect distillation system rises the cost of water by 15%.