Solar-powered water purification just got six times better

Solar-powered water filtration systems are gaining traction, if recent developments are any indication. A University of Ottawa graduate student’s desalination method is grabbing attention, first by winning the Ottawa Venture Tech Challenge, a $10,000 award, and by beginning to pick up funding to pursue his idea. According to the Globe and Mail, Mohammed Rasool Qtaishat began his journey to Ottawa in 2004, when he approached the Middle East Desalination Research Center in Oman with an idea for a water start-up. The center offered him a scholarship to come to Canada and develop his technology. Supposedly the efficiency of this method of water filtration is revolutionary relative to the system’s size, though the details are scarce. Judging by Mr. Qtaishat’s earlier publications, he’s using a technique called direct contact membrane distillation.

His breakthrough seems to be in the choice of material for the membrane, which is allowing him to produce about 13 gallons (50 kilograms) of water per square meter of membrane per hour, or about 6 times more than existing technology, which produces about 2 gallons under the same conditions. Even though he only recently has had the backing to perfect his device, the idea might be even older than Mr. Qtaishat: according to an interview, he says the technology is 40 years old but couldn’t be commercialized because of challenges in making the membrane.  He’s able to run the whole system on solar panels.

Direct contact membrane distillations works on a few basic principles—first, some compounds are removed from the beginning liquid through evaporation. Then, the vapor is passed through the membrane’s pores, which are designed to capture odd-sized, non-water particles. Finally the liquid is recaptured on the other side of the membrane as a condensate. Naturally, the choice of membrane is where virtually all innovation takes place.

Qtaishat’s design is not the first solar-powered water filtration technology, but if claims about its output efficiency are true, then good things may be on the horizon: the more powerful the devices, the more likely they’ll eventually make it into the developing world. A few portable solar-powered filtration systems from a company called WorldWater & Solar Technology are cleaning up water in Iraq. The company’s Mobile MaxPure devices can purify up to 30,000 gallons of water a day (remember—the size of the system is key to how much it can purify), off of a 3.2-kilowatt solar array. Others, too, are developing solar-powered water purification systems: in Australia, in New Mexico, and Germany, to name a few.


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