Water purification advances

Material researchers at Stanford have developed a new high-speed, low-cost water filter that can be used for water purification in developing countries. The filter is made from cotton dipped in a high-broth solution made of silver nano-wires and carbon nano-tubes; this forms a smooth continuous surface on the cotton fibres.

Unlike existing filters which trap bacteria, this new filter actually allows the pathogens to pass through because they are destroyed by an electric current of milli-amperes that flow through the conductive cotton. This makes it 80,000 times faster than the existing filters that trap the bacteria onto their surfaces.

This filter uses a new method of killing pathogens and can be used effectively in developing countries; people in such areas still suffer from water borne diseases like cholera, typhoid and hepatitis.

The filter has been designed with low cost materials which are widely available, chemically and mechanically robust. Besides, the electricity needed to operate the device is small; it can be easily obtained by using a small solar panel or 12V car battery and other means that are readily available.

Experimental results showed that the filter can achieve 98 percent efficiency; hence research is still ongoing in order to attain 100 percent efficiency, the gold standard, desirable for water purification. Also, the researchers will test this new filter on different bacteria to further improve its operation.