Remove Bacteria from Drinking Water Using Nanotechnology
Nanotechnology is being used to develop low-cost filtering technology for communities near contaminated water sources. Many water sources contain bacteria that cause diseases ranging from giardiasis (familiar to hikers) to cholera. While municipal water systems have methods to kill bacteria, many towns in developing countries don’t have municipal water systems.
Researchers at Stanford University have developed a low-cost water filter that combines silver nanowires, carbon nanotubes, and electricity to kill these bacteria. Conventional filters try to block bacteria and allow the clean water to flow through, but this method requires very small holes in the filter through which the water has to be pumped.
Nanotechnologists at Stanford figured out a way to make the holes in this filter large enough so that water would flow through without pumping.
However, bacteria can still pass through the filter. To get rid of most of the bacteria, they formed the filter material by dipping cotton fabric in a solution containing silver nanowires and carbon nanotubes. The cotton is coated with the nanotubes and nanowire, which allows it to conduct electricity. By applying 20 volts across the conductive filter, they can kill 98 percent of the bacteria.
Researchers think using multiple stages of the filter will get rid of the last few percent of bacteria. The silver in the nanowires will help prevent the growth of any bacteria on the filter, thus preventing fouling of the filter. This method is designed to be a low-cost, low-maintenance, and low-energy way to filter water for use in developing countries.