Solar-Powered Desalination System Combining Reverse Osmosis and Membrane Distillation to Enhance the Recovery Ratio

This study proposes and evaluates a standalone desalination system powered entirely by solar energy. The system integrates a Reverse Osmosis (RO) unit with Membrane Distillation (MD) units to minimize brine discharge. Both electrical and thermal energy are supplied by Concentrated Photovoltaic/Thermal (CPV/T) collectors. The primary objective of the RO-MD configuration is to enhance freshwater production, measured by the Recovery Ratio (RR), while relying exclusively on renewable energy sources. The analysis focuses on assessing improvements in RR, the resulting water flow rate, and the system's economic performance, specifically in terms of the Levelized Cost of Water (LCOW) and the amount of electrical energy generated. System performance is evaluated through dynamic simulations conducted over an entire year using real weather data from Almería, Spain. Results indicate that incorporating MD units in series with RO increases total water output by 7.99 % for a plant designed to operate 10 hours per day in July with an input flow rate of 10 m3/h. This leads to an improvement in water recovery from 41.06% (RO alone) to 44.34%. The LCOW is estimated at 6.68 USD/m3, which is lower than that of other desalination technologies powered by renewable energy.