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Water Filtration With a Tree Branch
Taco Cowboy writes "Dirty water is a major cause of mortality in the developing world. 'The most common water-borne pathogens are bacteria (e.g. Escherichia coli, Salmonella typhi, Vibrio cholerae), viruses (e.g. adenoviruses, enteroviruses, hepatitis, rotavirus), and protozoa (e.g. giardia). These pathogens cause child mortality and also contribute to malnutrition and stunted growth of children.' People have been working on engineering cheaper and cheaper filtration systems for years, but now a group of researchers has found a promising and simple solution: a tree branch. 'Approximately 3 cm^3 of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person.' 'Before experimenting with contaminated water, the group used water mixed with red ink particles ranging from 70 to 500 nanometers in size. After all the liquid passed through, the researchers sliced the sapwood in half lengthwise, and observed that much of the red dye was contained within the very top layers of the wood, while the filtrate, or filtered water, was clear. This experiment showed that sapwood is naturally able to filter out particles bigger than about 70 nanometers.' The team tested E. coli-contaminated water, and the branch was able to filter out 99 percent of the bacterial cells."
If this is true, then this is a really profound discovery that could help millions of people.
What I'm wondering, is why no other society, that we know of, has discovered this low-tech, yet seemingly incredibly useful thing previously?
I don't respond to AC's.
The most common water-borne pathogens are bacteria ...,viruses ...,and protozoa
Well, that pretty much covers it I guess. I was surprised the kingdom animalia didn't make it on the list, but then hey, I'm no biologist.
In all seriousness, this is a very interesting discovery and I hope it leads to cheap and widely accessible drinking water.
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
HA!
I always love it when somebody discovers a natural, free way to accomplish a goal that someone else wants to sell me a solution to.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
"It's so beautiful. It's hard to believe these spores could kill me."
Exactly how do you pour water THROUGH a branch? This sounds like the old boyscout prank of expecting someone to push a rope. Or maybe this is more like herding cats?
Do not meddle in the affairs of sysadmins, for they are subtle, and quick to anger.
Trees are great at dealing with bacteria.
http://faculty.vetmed.ucdavis....
http://en.wikipedia.org/wiki/Marah_(Bible)
"Somebody probably thought of that" is more likely to be untrue than true. You probably are the first person to think of that. And even if you aren't you might be the first person to act on the idea. And even if you aren't you might be the first person to succeed where others have failed. And even if you aren't, you might learn something. So don't ever say that, "somebody probably thought of that."
Filtering water through wafers of wood is not obvious to me. I do engineering for a living. If you are wondering why no one ever discovered something before, go back to paragraph one and repeat.
The article quoted above points to a paper that has some diagrams that shows how water would go through a branch -- no hoax here.
In brief, find a stalk of sappy wood -- my Dad showed us every spring how to make a whistle out of alder branches that look what the picture shows -- peel it, whittle it to size and then plug it into the end of a tube and gravity feed water through it.
simple...ank
Still hoping for Gentle Treatment...
from US water filtration corporations
Bacteria filtration is awesome for the wood filters.
Also, one has to be very careful not to let the wood dry out, because drying out damages the ability of the wood to pull water through, and if dried wood DOES let water through, it isn't filtered.
--PM
Is this really as simple as a stick with a funnel on top? How quickly does this process happen? How big of a stick do i need and how fast do they grow?
You can make a pretty decent biofilter simply by folding a piece of cotton cloth such as an old Indian sari a few times - it'll remove 99% of cholera and many other particularly nasty infectious agents. Yet people are still getting infected because they don't know about the simple solution - it's not a technology problem, it's a public information problem. And spreading public service announcements among a population where where most people don't even own a radio is a serious challenge. Doable, but expensive and there's no profit in it, so it usually falls to small humanitarian organizations that do their best to make the information go viral, and usually fail. Getting a meme to go viral is a lot more difficult when it can only spread through face-to-face interactions.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Showed this in his Costa Rica jungle episode.
I worked with an organization who did biosand filters in the Dominican republic and Haiti, they actually wanted there filters to leave a small amount of the bacteria because then it aloud the people who were using the filters to build up an resistance in case they ever drank water that was not filtered.
Tapping water from a tree is a well known survival technique. Getting water from vines even more so.
I believe archaeologists have found ancient village sites with a pit filled with layers of sand, charcoal, wood and plant fibers (crushed material, pounded on rocks ?), etc. It was the village water purification system. Not exactly wafers but interestingly close.
So with respect to things that humanity has been doing for millions of years, getting clean water in this case, I tend to be a little more open to the idea that a technique is being rediscovered rather than discovered.
I believe water purification via ultraviolet light (sunlight) using a titanium dioxide (cheap and safe) coating is the way to go simply because there is no consumable. In a nutshell when bombarded with UV light TiO2 kicks off 0H radicals that deactivate the in DNA of any nearby (~1cm) microorganism.
Mythbusters recently proved that you can't herd cats.
Not really, there were limited to politically correct methods. Replace the umbrellas with flaming torches, the cats will move.
Solar UV
...the next time I'm lost in the wilderness, now if I just had a pocket size air compressor to complete the process
After all its pretty well-known that from some trees you can get pretty good drinking water (as in: clean) so one would just naturally assume that somewhere between the roots and the trunk where you normally tap in, the thing would get filtered ... and alas there is not much in between except wood.
Charcoal is well known for it's use in purification. I'm curious if this works better than using charcoal and if the decay of the living tissue actually ends up making this less safe than just rendering that wood to charcoal.
Activated charcoal filters work via an entirely different mechanism than a porous membrane filter. Activated carbon works because the particles or granules have a honeycombed structure with a large surface area, and the surface of the carbon is chemically adhesive to certain types of molecules (particularly organic molecules).
'Rediscovered' by some schmuck in a lab so they can write a paper about the efficiency of it.
What I've always wondered is, how does the infection rate relate to the number of bacteria? Is "it only takes one" a true statement? I.e., if just one bacterium slips through the filter, are you as likely to get an infection as if a million slipped through? Or is there some "critical number" of bacteria, below which a normal immune system can easily handle things, but above which infection tends to set in?
That that is is that that that that is not is not.
From a water treatment standard 99% is only 2-log (factor of 100) removal. Most drinking water standards that we are familiar with range in the 4 to 6-log removal range. This level of removal is necessary when there are approximately 10^4 to 10^6 bacteria per mL of untreated water. This is a promising start, but still far from the final goal.
Its going to take more than osmosis (energy of some sort) to get water thru the branch in a reasonable amount of time
I have an idea, how about we use those branches to start a fire to boil the water???
Dumb question -- wouldn't it be easier just to burn the wood and boil the water...
I will try this out. If I post a report, you will know I survived...
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Welcome pedant, thank you for joining the party. Note how you had to pretend you didn't know the intention of the writer, that's the part where you can tell you've added no value to conversation.
But it works all the same. Which begs the question, are places that already have trees really in need of clean water and if so is the problem that there isn't already existing tech (such as charcoal+sand) vs the population knowing about existing tech.
This won't do any good where there is little rainfall and therefore no trees and it doesn't seem to be needed where there are trees and the ability to make charcoal if the population knew how to do that.
I am happy to add "use a living branch" to my bag of water purification tricks but I have to admit I see it as having limited utility since if I have living branches I can just make charcoal.