Singapore Water Anonymous: Micro Desalination Units

Yesterday, I mentioned that Siemens was fast tracking its desalination system. And I guess I now know why. It seems there're a whole lot of promising desalination technologies hot on its tail. Just over a month ago, I saw an exciting demonstration of a suitcase unit from Canadian Saltworks Technologies (though their low energy requirements are largely a result of tapping waste heat and solar energy). And now, there is this -- a desalination device that could fit in my handbag!

MIT scientists have come up with a new method of desalination, known as ion concentration polarization. Basically, an ion-selective membrane that repels all salts and microbes is placed in the salt water so water that does flow through is clean. This means no high energy costs of forcing water through membranes like in reverse osmosis, and no membrane fouling since the salts are repelled from the membrane.

And it gets even better. A 20cm diameter wafer can hold enough of these units so that 360L/day of water can be produced. Here in Singapore, people use about 155L of water everyday for all their daily needs including showering and cooking, so this would comfortably provide 2 people's supply of water in a handy portable device!

Nevertheless, there are some downsides to this system. Uncharged contaminants, mostly industrial pollutants, can't be removed by this method, so the unit has to be connected to some other filtration system. The scientists think a simple charcoal filter would work too. And the energy consumed, while definitely lower than a reverse osmosis system of the same capacity, would still be higher than the unit production cost of a full scale plant.

The scientists estimate it'll be another 2 years before this little unit hits the shelves. They're thinking of disaster relief applications. I think it might actually be a huge hit for beach events. No more cartons and cartons of mineral water bottles. Just a few of these nifty desalination units.