Turning a Tree Branch Into a Water Filter.


A false-color image of tree branch filter.In search of a low-cost and simple solution for filtering dirty water in developing nations, researchers have rediscovered the humble tree. A piece of freshly cut sapwood from pine trees can remove 99% of Escherichia coli bacteria in water, scientists report in PLOS ONE. Dirty water is a major cause of mortality in the developing world, and the old-school technology, which contains xylem (a porous tissue that can remove particles), could save millions of lives a year.
Figure 1 Xylem structure.Effective point-of-use devices for providing safe drinking water are urgently needed to reduce the global burden of waterborne disease. Here we show that plant xylem from the sapwood of coniferous trees – a readily available, inexpensive, biodegradable, and disposable material – can remove bacteria from water by simple pressure-driven filtration. Approximately 3 cm3 of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person. The results demonstrate the potential of plant xylem to address the need for pathogen-free drinking water in developing countries and resource-limited settings.