Low Cost Filtered Drinking Water

Many Americans may take clean drinking water for granted. Yet 768 million people do not have access to safe and clean drinking water. As many as 1,400 children die each day due to unclean drinking water. Currently there are more people who have mobile phones than a toilet. The average American taking a five minute shower uses more water than the average person in a developing country slum uses for an entire day. So as we can see, access clean water is a huge problem. Creating clean water across the globe would have enormous health benefits.

However, individuals at MIT are developing low cost methods of filtering water. Rohit Karnik, a mechanical engineer, found a very excellent method for filtering water that is natural. The method involves using the xylem tissue in plants for water filtration. The xylem allows plants to transport water in the form of sap from the roots to the leaves.

In conifer trees, the xylem has hollow tubes with diameters s of up to 80 µm and lengths of up to 10 mm. The cells grow in parallel and have closed ends. The water passes from one tube to another through holes which are known as pits. These pits are covered with nanoscale pores which can act as a filter.

In order to prove that this worked Karnik peeled the bark off a pine branch and placed the sapwood into a tube. He then sent a stream of water that was filled with tiny bacteria particles. The wood filter removed 99.9 percent of the bacteria. These are pretty substantial results under ideal lab conditions. Skeptics criticize these results because these ideal conditions will not be encountered in the real world. The development and research of these for mass production will take anywhere from 10-25 years before we can see these start to take some effect.

For now, there still exist some other methods that allow third world countries to safely drink water. One of these methods is known as Solar Water Disinfection (SODIS). Contaminated water is exposed to the sun for 6 hours. The UV-rays of the sun are strong enough to kill of diarrhea causing pathogens. This method is suitable for treating relatively small quantities of water. The WHO, UNICEF, and Red Cross all recommend it as a way to treat drinking water in developing countries.

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