What if someone told you that a small piece of sapwood from a pine tree could be used as an effect water filter — no pumps, batteries, or chemicals needed. Would you believe them or think that the story was a giant whopper?
Well, it’s no fib, as a team at MIT did just that. To make the filter, the team stripped the bark off white pine branches and placed it into a plastic tube. The porous tissue in the branch, called xylem, naturally filtered out the contaminants in water. “Today’s filtration membranes have nanoscale pores that are not something you can manufacture in a garage very easily,” said Rohit Karnik, associate professor of mechanical engineering at MIT. “The idea here is that we don’t need to fabricate a membrane, because it’s easily available. You can just take a piece of wood and make a filter out of it.”
According to a study published in the journal PLoS One, this makeshift filter can purify up to four liters of water a day and remove up to 99 percent of E. coli. The filter has the potential to be a game-changer in water-pinched communities around the world and in emergency situations.
The team is trying to find other types of natural filters. “There’s huge variation between plants. There could be much better plants out there that are suitable for this process,” said Karnik. “Ideally, a filter would be a thin slice of wood you could use for a few days, then throw it away and replace at almost no cost.” Maybe one day creating clean water could come be done right in your own backyard.