Slashdot Mirror
Researchers Develop "Tea Bag" Water Filter
cybernanga writes "A group of researchers in South Africa has developed a filter that can purify water straight from the bottle. The filter sits inside a tube fitted on top of a bottle and purifies water as it is poured on a cup. From the article: 'The designer behind the filter, Dr Eugene Cloete, from the Stellenbosch University in South Africa, says the filter is only as big as an ordinary tea bag. He says the product is cost-effective and easy to use. "We are coming in here at the fraction of the cost of anything else that is currently on the market," says Dr Cloete on BBC World Service.'"
Molecular paper thin water filters.
Because Slashdot isn't in the least liberal slanted and does not make inappropriate sexual comments about Tea Partygoers.
I must be a conservative! Oh, wait, why am I not in church right now?
http://www.waterfilters.net/SB-2-Water-Bottle-Filter.html
Isn't this essentially (from the looks of it) the same thing as the South African filter?
It's almost as if someone invented a disposable Brita water filter!
If moderation could change anything, it would be illegal.
So, it removes bacteria, but what about viruses, dont they need UV or RO to be removed??
Its just a bag of activated charcoal. Great at filtering out larger organics, not so good with microbial life forms and minerals.
I bought "cassette tape" sized bags of activated charcoal for my tropical fish tanks in the 80s. Glad to see the technology reinvented.
I'm not sure any amount of AC can protect fish from nearby rotenone spraying, then again its very hard to prove that without the AC bags my fish would not have died, its not like I was about to tempt fate. Thus plenty of opportunity for psuedo-science. Which MIGHT be where this product is headed, maybe.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
"We cover the tea bag material with nano-structured fibres, and instead of tea inside the tea bag, we incorporate activated carbon.
"The function of the activated carbon is to remove most of the dangerous chemicals that you would find in water."
1. It would have to be one shot - I don't see that little bag filtering more than one bottle.Wouldn't that little bit of carbon be exhausted after 500ml?
2. The pour rate would have to be really slow so that the water stays in contact with the carbon long enough to absorb the toxic stuff. Five minutes+ for a cup of water??
3. It doesn't say anything about metals.
RIP America
July 4, 1776 - September 11, 2001
A doctor that I knew back in the '70s did volunteer work for the World Health Organization, and spent a lot of time in some god-awful places. He told me that they would use Clorox bleach to purify their water. One cap full for a bucket of water. It tasted terrible, but as for the alternative for an industrial scale case of diarrhea . . . it was the lesser of two evils.
So I wonder how cheap this gadget is compared to Clorox?
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
http://www.campmor.com/aquamira-water-bottle-filter-kit.shtml?source=CI&ci_src=14110944&ci_sku=25674WC
For example, is what I have had for years to take backpacking. And they aren't even expensive. I guess I don't see how this is innovative.
a filter that can purify water straight from the bottle?
I could only find six other products that sound similar.
http://coffeetea.about.com/od/water/tp/waterbottles.htm
I don't understand how Tea Bagging cleans water.
I still do not understand the dilemma behind water purification on a small scale.
I know activated carbon is great at filtering out the stuff you can't see, and sand is great at filtering out the stuff you can see, but what about a simple water still? Once the crud has been removed by sand (no lack of abundance there), couldn't all the microbial stuff / viruses / bacteria be killed while the water is boiling? Not to mention the fact that extremely pure water can be made this way. (I used to be responsible for distilling water as a chem undergrad).
I suppose the only problems would be the fuel (wood and other biofuel consumption would suddenly take a hike), training (operating the still), and maintenance (cleaning the crud out). But this solution seems much easier than transporting activated carbon around in a tea bag...
On a large scale, a medium sized still could produce enough potable water for at least 100 people if operated full time.
I don't know about the "nano-fibers", though I've gotten to be suspicious of "nano" as a meaningless marketing term like "cyber" was ten years ago, but activated carbon's efficacy as a filter depends on how long it is kept in contact with the water, which is why those pricey tap filters are generally a waste of money. It's probably better than nothing if you're drinking water out of a stream or lake, but I'd be genuinely surprised if it was much better than nothing.
Proud member of the Weirdo-American community.
That would be home made Kombucha.
Do not drink the T-Bagger's water!
Better article says:
The inside of the tea bag material is coated with a thin film of biocides encapsulated within minute nanofibres, which kills all disease-causing microbes.
The bag is filled not with tea leaves but with active carbon granules that remove all harmful chemicals, for instance endocrine disruptors.
Each "tea bag" filter can clean one litre of the most polluted water to the point where it is 100% safe to drink.
Once used, the bag is thrown away, and a new one is inserted into the bottle neck.
Sounds good, but doesn't remove fine particulates or heavy metals, so you have to prefilter and chose your water source wisely (check arsenic contamination maps....)
Be very careful with the clorox method. The clorox product line is quite different today and you probably do not want to use the versions with stain removers and other additives for water purification. From the clorox website:
... Only Clorox Regular-Bleach, of all the bleaches mentioned on this website, is approved for sanitization and disinfection. ..."
"Disinfection of Drinking Water (Potable)
Also, does this approach work from bacteria to virus to cryptosporidium? My understanding is that the old school iodine tablets don't work on the later and that the military and NGOs have moved to chlorine dioxide based tablets. Much better tasting too. The caveat is that it takes something like 4 hours to kill the crypto compared to something like 15 to 30 minutes for the lesser "bugs". Being chlorine based maybe clorox could work with crypto but they don't seem to offer concentration or time guidelines. Perhaps they are just addressing North American concerns, maybe their sites for other parts of the world offer advice?
Answering my own question:
"Results of the present study show for the first time that C. parvum oocysts exposed to undiluted laundry bleach for as long as 120 min are infectious for animals. Although bleach is widely used as a bacterial and viral disinfectant, the present findings indicate that under practical conditions it is not an effective disinfectant for C. parvum oocysts."
http://aem.asm.org/cgi/reprint/61/2/844.pdf
Calling it a "tea bag" filter even though you don't use it like one (that is, place it in cup and let it sit for a while) is misleading. Should we call it a "USB thumb drive" water filter just because it's a similar size?
Not only is there the dubious claim that this will make water safe, and the implication that it is somehow different from other activated charcoal filters already made, but they stress how cheap or affordable it is, without ever giving any indication of a price. When someone tells you that something is inexpensive but doesn't want to tell you how much it will cost in any quantity, it will not be inexpensive.
I'm an American. I love this country and the freedoms that we used to have.
Hardly news.
"Half the cost of anything else out there" is very nice, but doesn't tell us much. Wandering around the web, I find the lowest (retail) cost to be around $.50/gallon for single packaged filters. (Which will obviously be considerably lower in bulk and/or multi-packaged.)
I wonder if a similar principal could be used to purify water after an oil spill?
Only 'flamers' flame!
Does slashdot hate my posts?
This sort of technology is my bailiwick. There are any number of cheap to free solar devices out there that can substitute for using wood or dung to heat water to boiling. Basically you set up a compounded reflector, you can use anything, scrap sheet metal, etc. You can also solar distill the water using nothing more than a sheet of plastic. Solar works remarkably well in hot areas like Africa.
This is some of the tech that should come stock installed in those OLPC devices going to the third world, how to purify water using local scrounged materials, how to cook without burning stuff, etc. The dudes in the developed world are just fixated on selling stuff, if they switched to pure education, it would help more people at much lower costs. They want to sell devices, gadgets, etc to governments, like this charcoal tea bag thing. The kids laptop is an exception, it is actually useful, because you can store so much text files on it that is practical information, simple line drawings/cartoons would work, you wouldn't even need to be able to read then to get useful information from it.
Since tea baggers can't filter bullshit, I image this causing a lot of e-coli spreading.
Where is the mod rating for "scary"? Also,
Inexpensive filter straws have been around for years. I don't see how this is that much better. There was nothing in the article about price or effectiveness of the filter itself. All we have is the designer's opinion, and of course he's naturally going to praise his own invention.
I'd rather pour it IN a cup rather than just on one.
it tastes salty.
ACTUAL SIZE!!!
I thought using the sun is good enough: Fill a PET bottle with water, leave it on your roof for a week. Given some African sun the water should be nearly sterile by then.
...
But then what about: the possible heavy metals, nasty chemicals, and what if there is no roof, and if it rains the whole week, can you wait a week,