How MIT Researchers use White Pine Tree Branches as effective a Xylem Water Filter

“Today’s filtration membranes have nanoscale pores that are not something you can manufacture in a garage very easily. 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.”

Dr. Rohit Karnik, Associate Professor of Mechanical Engineering at MIT

Activated Charcoal isn’t the only Water Filtration devices as noted in my blog article entitled “Going back to Mother Earth - How to Reuse the Brita Water Filter in your Brita Water Purification Pitcher without buying more Filters”.  

Nature already had a nano-Filter a long time ago. Researchers at MIT (Massachusetts Institute of Technology) have discovered that Tree Branches can be used as an effective Filter against E.Coli Bacteria as reported in “Water Filter Made from a Tree Branch Removes 99% of E. coli Bacteria”, published February 28, 2014 by permaculturepower. 

Their research paper was published at “Water Filtration Using Plant Xylem”, published February 26, 2014 by Rohit Karnik, Michael S. H. Boutilier et al, PLOS One and their research team consisted of the following members:

1.   Jongho Lee

2.   Michael S. H. Boutilier

3.   Rohit Karnik

4.   Valerie Chambers

5.   Varsha Venkatesh

Dr. Rohit Karnik, Associate Professor of Mechanical Engineering at MIT, used the xylem Transport system i.e. Tree Branch taken from a cutting from a White Pine. They stripped off the Bark and assembled their Filter as shown below and discovered that not only does it Filter dirty Water, making it potable again but acts as an effective Filter for particulates as small as 70 nanometer across, Filtering out bacterial elements such as E. Coli Bacteria.

When attached to a large reservoir of Dirty Water, it would take a most of the day to produce a lot of Filtered Water, but at least you'd be assured of its purity, if you don't mind the taste of Sap in your Water. It's a lot easier than building a Solar Desalinator as described my Geezam blog entitled “How to Make Distilled Water using a Solar Desalinator” and possibly can be made from other types of Wood locally available here in Jamaica, except of course for the poisonous Hemlock Branch!

Xylem Filter Springs a leak - Perfect Seal needed to ensure ultrapure Water free of Sap

One foreseeable issue that any Jamaican Plumber would spot is the problem creating a perfect seal. Using the above video and diagram, it’s clear that some of the Water that can’t go through the Filter will squeeze through the gap between the xylem Filter and the plastic tubing, dripping downwards and contaminating the Water.

Thus albeit the Water appears clean, it’s not exactly 100% pure. An improved design would incorporate the use of a hydrophobic Gel or sealant i.e. Caulk or Tangit Sealant that would first be used to coat the inside of the tube and the stripped Wood Bark before it’s placed into the Plastic tubing.

Also the Tree Branch used can’t contain too much sap, otherwise you contaminate the Water with Wood Bark sap and suspended xylem cells. The Tree Bark would have to be at least Vacuum dried i.e. placed in a vacuum to allow all moisture trapped inside to ooze out naturally, an expensive process but worth it if this were to ever be commercialized.

Still, at 70 nanometeres, this an effective albeit slow solution to treating dirty Water and making it potable without using Solar Methods. I suspect a wider branch with a larger cross-sectional area would Filter More Dirty Water Faster and when the Filter is clogged, the Water stops dripping through. Also, using dried Wood is out of the question albeit possible; this appears to be a case of using a moist Branch Cutting with as much sap removed as possible.

Make sure when you go backpacking you pack a knife, some Plastic tubing and Screw Clip as it may come in handy when no potable Water is nearby.