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Researchers Develop "Tea Bag" Water Filter 119

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.'"
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Researchers Develop "Tea Bag" Water Filter

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  • by jack2000 ( 1178961 ) on Sunday September 05, 2010 @10:48AM (#33481368)
    Molecular paper thin water filters.
    • Re: (Score:3, Interesting)

      by Joce640k ( 829181 )

      The filter in the article is just an ordinary active carbon filter. This [] is waaay better.

      • Re:Say it with me. (Score:4, Insightful)

        by TheLink ( 130905 ) on Sunday September 05, 2010 @11:23AM (#33481516) Journal
        And waaaay more expensive?

        I think their target market is "cheap", not "best".

        The "lifesaver" water bottle may save lives, but a few very rich lives :).

        This "tea bag" thing may not produce water as pure or safe, but might save many more lives if it really is cheaper, easy to use and practical.

        FWIW the 100% way to prevent many trillions of human deaths is to kill all humans now, so be careful if you ever ask a super smart AI to minimize the long term total number of human deaths per year ;).
        • I think you can buy them online for about $100 each. I bet you'd get a discount if you bought 1000.

          If they can do 6000 liters of water then the price is probably competitive with teabags. I guess it depends on how people are organized and how they pay for them. Individuals won't have $100 to spend but governments and humanitarian programs will.

          • My bad, the price I remembered was in pounds. They're $149 each and $300 for the jerrycan version: []

            • by aliquis ( 678370 )

              At 300 $ / can useful for 6000 liters isn't it better to drill a well?

              Best method however would most likely be:
              a) kill their leaders.
              b) confiscate all weapons.
              c) give them 100% freedom and democracy.
              d) have them ban import of foreign food.
              e) give them generous (as in not greedy) small loans.

              The rest they will solve themselves.

              Point a and b isn't really necessary if part c is in place.

              • Re: (Score:1, Insightful)

                by Anonymous Coward
                You forgot the "build infrastructure" part. That's important for parts c and e to succeed.

                And part d is likely inhumane.

                (Do you really think it's that easy? Take democracy, add water, poof! It's like a libertarian's wet dream)
                • by aliquis ( 678370 )

                  If they get anything working and some money I assume they can afford to build infrastructure at some point. I doubt it will just pop up from nowhere.

                  D isn't inhumane. Growing their own food would be more humane than depending on eventually getting hold of a surplus from the rest of the world, or not.

              • c) give them 100% freedom and democracy

                This clearly hasn't worked - read Amy Chua's "World on Fire" for an explanation of why. Better still, but probably too dense for the average reader is Barrington Moore's "Social Origins of Dictatorship and Democracy".

            • Re:Say it with me. (Score:5, Informative)

              by sjames ( 1099 ) on Sunday September 05, 2010 @03:28PM (#33482704) Homepage Journal

              With those prices and 3rd world exchange rates, they'll never develop their economies! They'd be in perpetual debt for water bottles.

              Even Britta costs a fraction of that, and, of course, chlorine bleach (as a pre-treatment to kill bacteria)is dirt cheap.

              Meanwhile, a solar still can be made with a bucket, a plastic sheet, and some manual labor. Unlike a filter, it will continue to produce clean safe water year after year with no expendable. The construction technique is simple enough that adult supervised children can do it (and learn a science lesson in the process with an immediate application).

              The developed world seems to have a bias against such solutions that don't make the 3rd world dependent on a continuous stream of "manna from heaven" in the form of manufactured goods. Part of that seems to be a bit of Marie Antoinette syndrome (just can't imagine a place where such cheap ubiquitous materials are expensive and rare). Part is that people imagine that accountant run businesses will lay off their drive for profit just a bit for the sake of humanitarian aid (they won't). Perhaps part because they might then start growing their own economy rather than becoming dirt cheap labor for our clothing industry.

              Meanwhile, much of the problem will stop when the developed world kindly stops selling greedy warlords automatic weapons and all the ammo they can carry.

              • by TheLink ( 130905 )
                > Meanwhile, much of the problem will stop when the developed world kindly stops selling greedy warlords automatic weapons and all the ammo they can carry.

                That bit is not true though. The machete has been used to kill millions and needs no ammo.

                I even saw a pic of a recent war/"clash" in Africa where a number of people were armed with bows, the rest with whatever they've got.

                As long as someone can convince other people to kill many you'll have wars.
                • by sjames ( 1099 )

                  To be certain, it wouldn't end all warfare, but it would limit it's scope considerably. It's a lot harder to keep desperate people suppressed when you can't just pick them off from 100 meters away.

                  When everyone has about the same weapons capability, there's a lot stronger incentive for leaders to make sure they're not TOO universally hated.

              • by howzit ( 1667699 )
                Woa, woa, woa...where do you get your prices? I LIVE 20 miles from the university. We are on a level here that you would not understand, so I won't try. We are wanting to SAVE LIVES . GEDDIT? Mainly rural South African lives. Mainly black South African lives. If you want to read about costs goto []. We are talking CENTS. So please talk SENSE., money, money. The South African tax payer is footing the bill OK??
                • by sjames ( 1099 )

                  Look at the post I was replying to for context (generally a good idea in a discussion forum). You'll see that I was talking about another product that sells for $150.00.

                  Once you realize that, the rest of my post probably seems a lot different, eh>?

        • Another cheap method for killing microbes is just to fill PET bottles (old coke bottles) with the water and leave them in the sun for a couple of days, of course the UV light breaks down not just the nasties but the bottle itself eventually.

      • Re: (Score:2, Interesting)

        by aliquis ( 678370 )

        I read that you can filter out e-coli or whatever common bacteria there was in water with a regular piece of cloth since the bacteria where grouped into bigger groups/particles.

        Too lazy to try to find the magazine but maybe someone else know what I was supposed to talk about :D

        Anyway, simple techniques can obviously be beneficial to, even if they won't solve all.

      • The filter in the article is just an ordinary active carbon filter. This [] is waaay better.

        Cool piece of equipment. It's basically an RO filter. The pressure required for operation comes from the user pumping it up with an air pump. It's also small enough to take camping or on long hikes if you have a source of untrusted water nearby.

    • Re: (Score:1, Offtopic)

      Eet's joost a waifer theen filter.

  • It's almost as if someone invented a disposable Brita water filter!

  • So, it removes bacteria, but what about viruses, dont they need UV or RO to be removed??

    • Re: (Score:3, Informative)

      by Joce640k ( 829181 )

      Leave the bottle in the sun for six hours to kill them (use a transparent PET bottle).

  • 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-s

  • Small filter (Score:2, Insightful)

    "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.

  • 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?

    • Re: (Score:2, Insightful)

      by Freddybear ( 1805256 )

      The charcoal filter would be good to use *after* you sanitized the water with chlorine bleach. Kill off the biologicals and then get rid of the chlorine taste.

    • Re: (Score:3, Informative)

      Yes but that solution doesn't remove any contaminants in the water; it only kills microbes.
      • Re: (Score:3, Interesting)

        Yes but that solution doesn't remove any contaminants in the water; it only kills microbes.

        The bleach will also break apart many kinds of contaminants, it won't remove heavy metals and whatnot, but I think bleach can break poisons.

        • The bleach will also break apart many kinds of contaminants, it won't remove heavy metals and whatnot, but I think bleach can break poisons.

          Depends on the poison. Heavy metals like lead are unaffected by bleach as is arsenic. Both are known to be in groundwater whether naturally occurring or by pollution. It's often best to filter water before disinfecting it. Even then, bleach is only partially effective against common pathogens. From wikipedia: "Neither chlorine (e.g., bleach) nor iodine alone is considered completely effective against Cryptosporidium, although they are partially effective against Giardia".

    • 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:
      "Disinfection of Drinking Water (Potable)
      ... Only Clorox Regular-Bleach, of all the bleaches mentioned on this website, is approved for sanitization and disinfection. ..."

      Also, does this approach work from bacteria to virus to cryptosporidium? My understanding is that the old s
      • 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." []
        • by Lehk228 ( 705449 )
          looks like a couple days in the sun will kill them off, so treat the water for a week in clear non-UV blocking containers, then bleach, then let sit for 24 hours and you should be good to go
      • Re: (Score:2, Informative)

        by aliquis ( 678370 ) []

        Clear and lukewarm: 2 drops 4-6% / liter of water.
        Murky or cold: 4 drops 4-6% / liter of water.

        Shake and wait for at least 30 minutes.

      • 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".

        There are basically two different types of treatment that work on two different types of microorganisms. Iodine and othe

    • by vlm ( 69642 )

      One cap full for a bucket of water. It tasted terrible,

      The water treatment guys screwed up. Chlorinated water shouldn't taste awful after purification, certainly not even as bad as swimming pool water. The "art" of chlorination is to use just enough hypochlorite to oxidize all the microbial life, anything over and above that is wasting supplies, aim for the "faintest taste of chlorine". Also you can aerate the water, just pouring it from cup to cup for a few minutes will help noticeably. Storing treated water after Cl dissipates will allow whatever was grow

    • by aliquis ( 678370 )

      I think the chlorine taste may disappear by itself if you let the water sit for long enough (with ventilation that is)


    • As someone who also lived in some god-aweful places, I'll tell you one cap for a bucket of water is going to burn your throat (unless it's a really big bucket). Usually you want no more than 8 drops of chlorine per gallon of water.
    • One of the hats I wear is that of an emergency water engineer in disasters, conflicts and other public health emergencies. I've worked all over Africa, SE Asia and now the Caribbean.

      One cap of chlorox is beyond excessive and detrimental to anyone who would drink it. Bleach to chlorinate water is okay in an truly urgent situation but is not an idea solution.

      Your question implies that your understanding is that filtering versus chlorination are processes that are exclusive of the other. In almost every sit

  • by Anonymous Coward

    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.

    • Well, it can go in *any* bottle, rather than needing a special bottle, meaning that you don't need to worry about losing your special bottle in areas where social stability is ephemeral at best. So a filter that can go in any old bottle you have laying around, and can be made cheaply, and is small, yes, is innovative. Sometimes it's not about function, it's about form.

  • 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.

  • by Anonymous Coward

    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 i

  • 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?
  • by frovingslosh ( 582462 ) on Sunday September 05, 2010 @12:38PM (#33481886)
    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.
    • by mrmeval ( 662166 )

      I agree. I've seen many of the water purification straws which make a claim of making water safe but they never back it up with independent testing. These do have reams of association approvals and testimonials but no testing. I found and tried one that made claims of being tested by the military and that it had reams of testing done. I found that with great effort it worked for about two liters and then clogged and was useless. I didn't have to pay for it and didn't bother trying one again.

      I have bought o

      • Can you provide some info. on the system that passed military testing?
        • by mrmeval ( 662166 )

          It's a filter with washable inlet filter, charcoal filter then a ceramic block. I've abused it and the brand name and product name are gone, sorry. I remember the process I used to find it but don't recall who I bought it from or what the brand name is.

          You can google Individual Water Purifier mil spec and look for ones that are issued to troops. I was in error on having an NSN being enough and someone I know berated me for that.

          You should request information from them such as "What military specifications d

  • "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.)

  • Something like this may be useful in aquariums when doing water changes if it could purify a few gallons of water and was cost effective.

    I wonder if a similar principal could be used to purify water after an oil spill?

  • Thats too bad (Score:1, Flamebait)

    Since tea baggers can't filter bullshit, I image this causing a lot of e-coli spreading.

  • What else is new? (Score:3, Informative)

    by reboot246 ( 623534 ) on Sunday September 05, 2010 @05:10PM (#33483418) Homepage
    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 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, ...

Things equal to nothing else are equal to each other.