MIT researchers have found that low tech water filters are all around us in the form of pine trees.
It’s a scenario no one wants to find themselves in. You have wandered off the trail and are critically low on clean drinking water. Thanks to MIT a simple filter solution is available with the aid of a pine tree.
Simply break off a branch, shave away the bark, and tightly jam it into the opening of your water bottle. Next slowly pour water through the branch and into your bottle, producing fresh drinking water.
It may sound risky, but a team at MIT have the research to back it up. You can read all the technical information in their published work at PLoS ONE.
They found that even a small piece of freshly cut pine wood can filter out up to 99 percent of bacteria from soiled water. This simple solution is also capable of filtering up to 4 liters of water per day, which is way more than the average person would need to survive.
The reason it works so well is do to the tons of tiny pores in the sapwood. This xylem tissue allows the tree to transport sap throughout itself while stopping harmful bubbles that could kill it. This is similar to how a water filter works to block bacteria.
“Plants had to figure out how to filter out bubbles, but allow easy flow of sap,” said researcher Rohit Karnik. “It’s the same problem with water filtration where we want to filter out microbes, but maintain a high flow rate. So it’s a nice coincidence that the problems are similar.”
They ran tests ranging from pouring red dye through the wood to using inactivated E. coli with much success. The method they chose to run these tests with is actually a pretty simple and easy to make filter on its own as you can see in the picture below.
Their findings soon found that the pine wood can only filter particles down to 70 nanometers. The smallest of most harmful bacteria is around 200 nanometers, but viruses are much smaller at the 20 and below range.
Tests with dry wood did not bode well showing the sapwood must be fresh or at least stay moist. In their tests they found that water did not flow through well, or remained unfiltered due to tiny cracks forming on the dry wood.
The group is now looking into other plants or trees that may serve as a better filter. Flowering trees have smaller pores than coniferous ones making them better candidates to possibly filter viruses.
This research is on the verge of being able to create cheaply made water filters. These could then be used the world over in places with unsafe drinking water, or so they hope.
“There’s huge variation between plants,” said Karnik. “There could be much better plants out there that are suitable for this process. Ideally, a filter would be a thin slice of wood you could use for days, then throw away and replace at almost no cost.”
This information may be a few years old, but it is invaluable to those in the wilderness. With dehydration the number one killer of people who get lost, this could be a life saver.