MIT creates wood filters for drinking water that neutralize pathogens

Inside non-flowering trees such as pine and ginkgo, there is sapwood lined with thatch channels,

xylems, which draw water through the trunk and branches of a tree. The xylems are interconnected by thin membranes that act as natural sieves, filtering out bubbles from water and juice.

Massachusetts Technological EngineersInstitute 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.

Sapwood xylem tissue of gymnospermscan be used to filter water (as shown above). Xylem consists of channels that are interconnected by membranes that filter out impurities present in the water (below). Credit: N.R. Fuller, Sayo Studio.

Now the same team has improved the technologyand showed that it works in real 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 disks are able to purify water for at least two years.

Their results, published today inNature Communications,show that xylem filters canused in public places to remove bacteria and viruses from contaminated drinking water. Prototypes tested in India show promise as a low-cost natural filtration option.

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