Providing a simple, cheap, and sustainable method for filtering dirty water is that simple, according to a new study published this week in PLoS ONE. The study demonstrates that a 2 cm long piece of branch with a 1 cm diameter can filter 99.9% of the E. coli out of a water sample and that each segment could be effective for a few liters a day. Not surprisingly, it needs to be fresh branch wood, not dried.
It's clear that this paper is a proof of concept and that a lot of work remains to be done. The authors, all mechanical engineers at MIT, did an admirable job of teaching themselves about xylem...I wonder how these efforts could be advanced more rapidly with some help from the plant ecophysiologists among us. Nevertheless, my understanding is that cheap and efficient water filters are something of a holy grail...nearly 1 billion people still do not have access to clean water. Imagine the possibilities this could inspire...
Torus-margo pit. The torus is the valve (pancake) in the center and the margo is the membrane (spiderweb). From Choat et al. (2008).
Boutilier et al. 2014. Water filtration using plant xylem. PLoS ONE 9(2): e89934.