Solar Water Desalination

Desalination has a strategic importance in the MENA region as a main source of fresh water. The UAE has become leader in implementing alternative methods for creating fresh water resources through desalination. Majority proportion (43%) of it is consumed mostly as potable and household water. A recent survey in UAE reveals that only 6% of people drink tap water due to potential health and safety concerns over tap water. This brings in the big picture of reliance of bottled water by urban population and in fact, UAE stands top as a largest per capita bottled water consumer in the world. Desalination itself is high energy consuming process and researchers around the world striving to perfect the process of desalination, making it efficient and cost-effective. But purifying the desalinated water again for bottling adds more energy along the conversion chain and the potential environmental impact of plastic waste makes bottling process highly unsustainable.

The need for sustainable approach to tackle the issue of bottled water has motivated us to develop an in-house water purification unit based on Membrane Distillation (MD) technology. MD is a novel process that could be adapted effectively for many water purification applications. A difference in partial pressure serves as the driving force, and the presence of a hydrophobic membrane ensures high water quality regardless of feedstock parameters. Hot-side temperatures below 90ºC are suitable and this process has been proven ideal for exploiting waste heat or solar thermal resources for small scale applications.

At RAK research and innovation center, we developed an integrated system of MD into solar hot water system that can produce 2 l/hr of distillate along with fulfilling hot water demand of a single family dwelling of five in the region. The proposed co-generation system would be ideal for maximizing the solar fraction through production of pure water in summer and thus reducing backup heating requirement. Overall thermal performance of system could be increased and additionally acts as a source for pure distilled water. Present research study provides design and development of a pilot test prototype for technical evaluation of MD modules and solar thermal collectors suitable for the co-generation application.