When it comes to providing for the future, clean, drinkable water is one challenge researchers are seriously looking into. Not only is overpopulation seriously depleting the world’s supply of fresh water, Climate Change threatens to make a bad situation even worse. As sea levels rise and flooding threatens population centers, water tables are also drying up and being ruined by toxic chemicals and runoff.
One idea is to take sea water, which is in growing supply thanks to the melting polar ice caps, and making it drinkable. However, desalination, in its traditional form, is an expensive and difficult process. Typical large-scale desalination involves forcing salt water through a membrane are costly, can be fouled, and which require powerful pumps to circulate the water.
However, scientists from the University of Texas at Austin and Germany’s University of Marburg are taking another approach. Working with a process known as “electrochemically mediated seawater desalination”, they have developed a prototype plastic “water chip” that contains a microchannel which branches in two, separating salt from water chemically without the need for membranes.
The process begins with seawater being run into the microchannel where a 3-volt electrical current is applied. This causes an electrode embedded at the branching point of the channel to neutralize some of the chloride ions in the water, which in turn increases the electrical field at that point. That area of increased current, called an ion depletion zone, diverts the salt to one branch in the channel while allowing the water to continue down another.
In its present form, the system can run on so little energy that a store-bought battery is all that’s required as a power source. Developed on a larger scale, such chips could be employed in future offshore developments – such as Lillypad cities or planned coastal arcologies like NOAH, BOA, or Shimizu Mega-City – where they would be responsible for periodically turning water that was piped in from the sea into something drinkable and useable for crops.
Two challenges still need to be overcome, however. First of all, the chip currently removes only 25 percent of the salt from the water. 99 percent must be removed in order for seawater to be considered drinkable. Second, the system must be scaled up in order to be practical. It presently produces about 40 nanoliters of desalted water per minute.
That being said, the scientists are confident that with further research, they can rectify both issues. And with the involvement of Okeanos Technologies – a major desalination research firm – and the pressing need to come up with affordable solutions, it shouldn’t be too long until a fully-scaled, 99 percent efficient model is developed.