Scientists at the Massachusetts Institute of Technology used the sapwood of non-flowering trees to create a filter for drinking water from natural materials.
Inside non-flowering trees such as pine and ginkgo, there is sapwood lined with straw canals, xylem, which draw water through the trunk and branches of the tree. Xylems are interconnected by thin membranes that act like natural sieves, filtering bubbles from water and juice.
MIT engineers investigated the properties of sapwood and made simple filters from cleaned cross-sections of sapwood branches. It turned out that the low-tech design effectively filters bacteria.
Now the same team has perfected the technology and shown it to work in real-world situations. They made new xylem filters that filter out pathogens such as E. coli and rotavirus. Laboratory tests have confirmed that their development removes bacteria from contaminated springs and groundwater. Scientists have also developed simple methods to extend the shelf life of filters. As a result, wood discs are able to purify water for at least two years.
Their results, published today in Nature Communications, show that xylem filters can be used in public places to remove bacteria and viruses from contaminated drinking water. Prototypes tested in India show promise as a low-cost option for natural filtration.