March 19th, 2014 by

One billion people across the world don’t have access to clean drinking water, and waterborne disease kills millions of people, notably children, each year.

A researcher at the Massachusetts Institute of Technology (MIT) is developing a potentially game-changing water filtration system from an unlikely source: trees.

Dr. Rohit Karnik, a mechanical engineering professor at MIT, is using sapwood from coniferous trees — mainly pine — to remove fatal pathogens from water. Sapwood, scientifically known as xylem, is the outer layer of plant tissue that carries water upward from a tree’s roots towards its canopy.

Credit: thisisexcellent/Flickr.

Current water-treatment techniques are rather inefficient for small towns and villages, ranging from chlorine treatment that is better used for large-scale decontamination to boiling water, which requires the use of fuel. Additionally, some procedures don’t completely remove pathogens, limiting their overall effectiveness.

The plant-based alternative that Dr. Karnik and his team are developing can remove 99.9 percent of bacteria from water by simulating a tree’s natural pressure-driven filtration process. A piece of sapwood roughly 3 cm3 can filter several liters of water per day, which can provide clean water for one person. Sapwood from conifers is also an inexpensive, biodegradable and accessible resource, making it a viable alternative to other eco-friendly filtration techniques such as ceramic filters or bio-sand systems.

One drawback to xylem filtration is the need for a constant water source, something that Karnik says could be resolved with more research. Further experimentation could also identify sources of xylem from plants other than conifers, as many regions plagued by water quality issues cannot support coniferous trees.