Study: Sapwood Could Work as a Water Filter

About the only thing I remember from my sophomore biology class is having to draw a microscopic cross section of a plant stem. All those little cells took what seemed like hours to sketch, but I guess the exercise worked in that, to this day, I understand how liquids - both water and sap - travel throughout the plant. Turns out, that knowledge could be useful in the woods. Researchers from MIT recently discovered that certain sapwoods like white pine can serve as improvised water filters.

Researchers collected white pine branches and stripped off the outer bark. The pine was then cut into one-inch long pieces and fitted into plastic tubing to create a filter. When researchers passed water through the sapwood, they found it filtered more than 99 percent of the E. coli bacteria present. They believe the tissue in sapwood used to transport sap also allows water to pass while blocking most types of bacteria. Most viruses will likely pass through these tissues because they are much smaller than bacteria, researchers say.

Rohit Karnik, study co-author and an associate professor of mechanical engineering at MIT, says sapwood is a promising, low-cost, and efficient material for water filtration, particularly for rural communities where more advanced filtration systems are not readily accessible.

Now before you run out into the woods and start plugging pine branches into straws, you should realize the system is neither proven, nor very time-efficient. As seen in an accompanying video, only a small vial of water was filtered over the course of nearly an hour. Still, it does offer some potential and, as the study states, may be a viable way to bring clean water to third-world communities. The study was published in the journal PLoS ONE.