One way to clean harmful bacteria from river water is to pump it through costly man-made filters. But scientists may have discovered much more affordable technology, fully developed and ready for use, beneath the bark of an ordinary tree.
NPR reports that MIT scientist Rohit Karnik strained water through the sapwood of a pine branch. The branch's vascular system contains membranes designed to filter out microscopic air bubbles. Karnik found that those same membranes could filter out harmful bacteria as well, apparently as much as 99.9%.
The remaining iota could still pose a serious public health risk, skeptics caution. For the moment, though, it's an intriguing proof of concept and also evidence that sometimes invention is just catching a ride on nature's coattails.