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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."
Filtering out "99%" of harmful bacteria may be like filtering out 99% of bullets fired at you....
Ideas can be publicized, studied in more detail, or put to good use, without being truly new.
24So the people grumbled at Moses, saying, "What shall we drink?" 25Then he cried out to the LORD, and the LORD showed him a tree; and he threw it into the waters, and the waters became sweet.
Trees are great at dealing with bacteria.
http://faculty.vetmed.ucdavis....
Filtering out "99%" of harmful bacteria may be like filtering out 99% of bullets fired at you....
So, I take it you're not a fan of Lysol or Purell?
What a silly thing to say; as if not filtering 99% of something harmful is a better idea...
An enigma, wrapped in a riddle, shrouded in bacon and cheese
"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.
Take what? Take their money to the bank when their plastic funnels and tree-branch-filtration kits sell like hotcakes to the very folks hoping to, ahem, "stick" it to the man?
Account -> Discussions -> Disable Sigs
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?
Maybe because all of the other materials and equipment required to make it work.
You mean like some sort of cutting implement to cut down the branch?
I think the hatchet was invented at least 10 years ago?
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?
Well, I learned this technique as part of my Aboriginal American studies when I was growing up -- I think it's more likely that our western culture has "lost" this knowledge than that nobody has discovered it before.
1) Someone mentions a new discovery.
2) Find a passage in the Bible containing the (rather common) keywords, without actually using your brain to check that the passage has identical informational value.
3) ???
4) Prophet!
Ezekiel 23:20
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?
For one thing, it doesn't filter viruses, so maybe it's already been evaluated and dicarded as a good solution. From TFA:
Karnik says sapwood likely can filter most types of bacteria, the smallest of which measure about 200 nanometers. However, the filter probably cannot trap most viruses, which are much smaller in size.
So it's of limited utility, since, as the summary says, common pathogens include viruses (e.g. adenoviruses, enteroviruses, hepatitis, rotavirus) -- for example, rotavirus is around 30nm in size, less than half the effective filtering size of the wood.
So the water will probably still need chemical or UV treatment after filtering.
Plus it's not clear how well it would work in the field, when the scientists built their filter:
They cut small sections of sapwood measuring about an inch long and half an inch wide, and mounted each in plastic tubing, sealed with epoxy and secured with clamps.
So while wood as a filter medium sounds attractive, if the user needs specialized equipment to get it to make a safe, water-tight seal, maybe it's not as useful in an area with limited resources.
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.
Water-borne pathogens in the kingdom Animalia are usually called "predators" rather than "pathogens". But yes, pathogens such as A. Mississippiensis can be filtered from the water with an appropriately-sized tree branch.