Portable and integrated solar-driven desalination system using membrane distillation for arid remote areas in Saudi Arabia

• We developed a portable solar-driven desalination system for producing potable water. • A stand-alone system which utilizes solar energy by combining PV/thermal collectors. • The system uses Vacuum-Multi Effect Membrane Distillation (V-MEMD) process. • We also reported some small-scale test results of the performance of the system.

An integrated solar-driven desalination system using the memsys VMEMD process has been developed. The memsys process was successfully integrated with a solar-thermal and solar-PV system. Studies of this system are currently being conducted at King Saud University, Saudi Arabia. Small-scale tests have been conducted during two different seasons (spring vs. winter) to evaluate the performance of the system. The system ran perfectly and only utilized solar energy without external energy from the grid. Based on the results, the largest amount of water was produced by Test E (99.6 L) under the following conditions: heat pump utilization, a higher thermal-tank temperature, a low feed flow rate, and high solar radiation. The average conductivity of the distilled water produced by the system was 6.2 μs/cm. The optimum feed flow rate was 69 L/h. In general, based on the result of all the tests, the use of the heat pump gave the most contribution to optimizing the system performance. The use of heat pump significantly increased the distillate output, almost double of that without the heat pump. Automated control of the system will be tested in the near future to achieve a fully Table 8 The results of Test B (with heat pump) and Test C (without heat pump). Test Date Heat pump Feed (L/h) T_Feed (range) (°C) Distillate output Time lag (initial) B C 18 Feb 2013 19 Feb 2013 YES NO Avg. rate (L) (L/h) (μs/cm) 1°:16 20–51 20–26 Total (h°:min ) Conductivity 67.8 34.8 11.24 5.98 4.7 5.3 Table 9 The effect of different evaporator and condenser flow rates. Test Date Heat pump Feed (L/h) Evaporator (L/h) Condenser (L/h) Distillate (L/h) H I 25 Feb 2013 26 Feb 2013 NO NO 63.6 43.3 51.6 automated system (Auto mode). Successful development of the solardriven desalination system will be useful for the Kingdom of Saudi Arabia. The system utilizes renewable solar energy for its operation instead of fossil fuels. With this technique, the oil reserves in Saudi Arabia can be saved for other uses. Indirectly, this system will also reduce CO2 emissions (global warming) from the use of fossil fuels in most desalination plants in Saudi Arabia. Thus, this system can serve as a model of sustainable desalination technology for the future when there are no oil reserves remaining in Saudi Arabia.