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A Water Filter Made From A Tree Branch!
For preppers, hikers (really anyone who is likely to find themselves in need of getting clean water in an emergency) to keep in mind, here is an interesting discovery. It’s ease of use and extremely low cost means it would be of great benefit to people living in emergency situations, remote areas or third world countries where clean water is very difficult to obtain.
For people in many developing countries, clean water is often a luxury. Chlorine treatments are too expensive for small villages, boiling requires a hefty investment in fuel, and UV radiation demands regular high-tech maintenance.
But now, scientists say that a simple, inexpensive water filter might be only a tree branch away from reality.
Inexpensive Tree Branch For Filtering Water
MIT researchers has discovered that running contaminated water through a sapwood branch successfully filtered experimental dye and actual bacteria out of the mix. The filter needs just a fresh branch of white pine and along with some very cheap plastic tubing.
“It’s too early to compare, but with further development of xylem-based filters, I think it would be fair to compare it to other filtering methods,” says Rohit Karnik, mechanical engineer at MIT and coauthor of the study.
Karnik’s sapwood filters harness the hardware already built into plant tissue. In transit from plant’s roots to its leaves, water bounces through a meshwork xylem, a series of conduits and membranes with tiny pores that blocks bubbles from clogging the system.
Karnik first heard about these plant pores at a NATO-sponsored conference in 2012. “I listened to this talk about how water flows through plants, and it occurred to me that the flow of water has to pass through these membranes in xylem,” he says.
After further investigation, Karnik discovered that most xylem pores are about the same size as the average pathogenic bacterium. Intrigued by the possibility of using plant tissue to filter bacteria out of water, he recruited Varsha Venkatesh, a high school student from New Jersey and coauthor of the paper, to run preliminary experiments.
By the end of last summer, the lab began to see positive results. “We tried freshly cut sapwood and found that it actually works,” Karnik says. “We were able to show that it can filter bacteria out of water.” via popularmechanics.com
Filters 99 % of E. Coli
In a paper published this week in the journal PLoS ONE, the researchers demonstrate that a small piece of sapwood can filter out more than 99 percent of the bacteria E. coli from water.
They say the size of the pores in sapwood — which contains xylem tissue evolved to transport sap up the length of a tree — also allows water through while blocking most types of bacteria.
Co-author Rohit Karnik, 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.
“Today’s filtration membranes have nanoscale pores that are not something you can manufacture in a garage very easily,” Karnik says. “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.” via newsoffice.mit.edu
“There’s huge variation between plants,” Karnik says. “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 a few days, then throw it away and replace at almost no cost. It’s orders of magnitude cheaper than the high-end membranes on the market today.”
While the pores in sapwood are too big to filter out salts, Saurya Prakash, an assistant professor of mechanical engineering at Ohio State University, says the design could be useful in parts of the world where people collect surface water, which can be polluted with fine dust and particles of decaying plant and animal matter.
Most of this detritus, Prakash says, could easily be filtered out by the group’s design.
“The xylem tissue acts as a natural filter, similar to a manmade membrane,” says Prakash, who was not involved in the research. “The study by the Karnik group shows that use of abundant, naturally occurring materials could pave the way for a new generation of water filters that are potentially low-cost enough to be disposable.”
This research was supported by the James H. Ferry Jr. Fund for Innovation in Research Education. Read the reasearch pdf: http://www.plos.org/wp-content/uploads/2013/05/pone-9-2-boutilier.pdf