Solar Water Distillation

Discussion in 'Designing, building, making and powering your life' started by Peter Clements, Jul 4, 2006.

  1. Peter Clements

    Peter Clements Junior Member

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    Has anyone heard of a method for solar distillation of drinking water? After reading about experiments done by the Gaviotas community in South America, where they rigged a solar hot water heater up to a distillation rig, has anyone seen some details on how it's done?
     
  2. Richard on Maui

    Richard on Maui Junior Member

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    I have seen it done once or twice Peter. Basically, a sheet of plastic is set over an evaporation pan which is filled with water. The sun heats the water up until it becomes vapour, then the vapour condenses on the plastic and runs down to gutters where it is collected. The kinds that I have seen have been setup to demonstrate that it is possible, but wouldn't be all that practical to purify water on a very large scale. but it would simply be a matter of making the unit a lot bigger I guess.
     
  3. christopher

    christopher Junior Member

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    Hi Peter,

    Try https://www.solaqua.com/solstilbas.html They have a few models.

    Its ot that hard. I know people who have done it here with sea water on the cayes, making salt and water.

    Good luck!

    C
     
  4. Michaelangelica

    Michaelangelica Junior Member

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    Pictures of solar stills

    If you google "Solar still" in the pictures section of Google Search Engine (use the "")you should get about 100 photos.

    I am working on a design myself.

    The Federal Government gave $150,000+ to a comapany called Eyre Enterprises in SA to market a solar still in some environmental awards a few years ago.
    They seem to have disappeared with the money and the still design.
    Anyone heard of them?
     
  5. blackash

    blackash Junior Member

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    Heard this guy on the radio national,
    He made an Solar Water Purifier
    His name is John Ward
    This is the last bit of the interview. John is talking.
    "My original thought was totally based upon humanitarian views which I’ve got and I wanted to cater for individual families, living under very poor conditions with effectively no money, barely living from day to day, having no access to electricity or a government-organised reticulated water system, so I thought I’d start at the very bottom end with a family that might need around 10 litres of water per day, of pure water which wouldn’t give them any more diseases than they’ve got already. So my target I think, has been achieved. It’s something which is portable, it has a handle on it just like a suitcase, you can set it up in any sunny location, you can fill it with bore water, sea water, urine, effluent, radio-active water and drink with equanimity what comes out of it."
    Here a link to the transcript.
    https://www.abc.net.au/ra/innovations/st ... 102910.htm
    Here is a link to his web site
    https://www.solarwaterpurifier.com
     
  6. Jez

    Jez Junior Member

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    Thanks Blackash - it's definitely very interesting technology.

    From what I've heard he's going to be on The New Inventors soon so it will be worth keeping an eye out for anyone wanting to see this unit in more detail.

    Does anyone know what exactly is the difference between this unit and 'solar pasteurisation' - as in these units which are very cheap and would (at least at face value) produce a lot more 'clean' water a day for your initial outlay.

    I assume pasteurisation would just kill bacteria when you're starting with bacteria laden water - so you couldn't start with effluent,remove mineral content, radiation etc.

    Anyone able to clarify the distinction between pasteurisation and the end product from the solar water purifier?
     
  7. Jim Bob

    Jim Bob Junior Member

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    Interesting, the guy says on his website it's really cheap, but gives no price for it ;)

    Jez, the difference between pasteurisation and distillation is this.

    In pasteurisation, the water is boiled, but stays in one vessel/bag/pot/whatever. So bacteria are killed, but any minerals, etc stay in there.

    In distillation, the water is evapourated. This may, or may not, kill any bacteria (needs to be over 85 degrees for ten minutes to kill most bacteria). But it removes the mineral content, and/or oils, soaps, etc. To get an idea of what happens, put a pot of water on the stove, pour in a heap of salt. Then boil away the water. You'll see that salt gets left behind. (Just don't add water to the hot pot later, instead leave it aside to cool, the sudden water on it will give you a steam blast which could burn you.)

    So pasteurisation is good for killing poisonous bugs, but won't turn salt or bore water into fresh drinking water. Whereas distillation usually won't kill bugs, but will remove the minerals, etc.

    Distillation can be done really hot, and this'll kill the bugs - but solar distillation won't be that hot. It won't achieve that 85+ degrees for ten minutes which you need to kill (most) bugs.
     
  8. Jez

    Jez Junior Member

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    Thanks Jim Bob, I figured that was the difference but I wasn't entirely sure.

    I assumed he doesn't have a price for the unit because he mentions on the site that they need to raise about a million dollars to start manufacturing them in bulk cheaply...seems (quite rightly IMO) disappointed he's received no development funding whatsoever from the government.
     
  9. Arby

    Arby Junior Member

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    Distillers are actually considered "purifiers" and from every thing I have read, they do take care of microorganisms...and in the same way they take care of other contaminates.

    Here's a decent link with additional links at the bottom:

    https://www.motherearthnews.com/Alternat ... lar_Stills

    Arby
     
  10. Jim Bob

    Jim Bob Junior Member

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    It depends on the temperature they reach, Arby.

    If you put a dish on top of a bowl of water on your back porch, you'll get water condensing on the dish. But that water won't be sterile. It's only sterile if it reaches a temperature of above 85 degrees for ten minutes. By comparison, a shower is 50-60 degrees, more than that burns you.

    If you're sure that a regular solar distiller will get rid of microrganisms, then try this experiment. Poo in a bucket, mush it up with some water, then put that water through a distiller. If the water makes you sick, it wasn't sterile. And if you're not willing to try the experiment, then I guess you've not that much faith in the distillation, yeah? 8)
     
  11. Arby

    Arby Junior Member

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    Jim Bob,

    From everything I have read, I was under the impression that vaporized water was light enough as it rose to leave everything behind, including microorganisms.

    I also don't understand your analogy of getting water to condense on a dish. I don't believe distillers are meant to sterilize via heat but rather sterilize by seperation. I believe they separate the good from the bad by the process of vaporization, not condensation. To condense means to cause a gas or vapor to change into a liquid. Distillers vaporize the water (the junk being heavier can't rise with the light weight steam) then condenses (changes to water) and drips into the holding tank. Am I making any sense here? It is a couple hours past my bedtime.:?

    I'm not necessarily doubting you as I have been wrong more times than I care to admit. I just haven't seen any reference that coincides with what you're saying here. Provide me a link to some reading material then I won't have to experiment with my poo. :lol:
     
  12. blackash

    blackash Junior Member

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    Hi guys,
    This is what John Ward as to say about his distiller. This guy is an Australian physicist. So one hopes that he knows what he is talking about... :D

    Question from the interviewer...Well, your Solar Water Purifier has no filters, has no electronics, has no moving parts and uses no chemicals, so more on how it works.

    His reply...WARD : Right. We have a box which is about a metre long and half a metre wide and 0.1 of a metre deep with a glass lid on it. Around the edge of the box is an aluminium frame to hold everything together and inside the box is a piece of black plastic, which is divided up into little square pockets. The water comes in at the top of this box when the box is inclined at 10-12 degrees to the horizontal. It flows down in series through 32 of these little pockets and, when they’re finally all full, you stop the water flowing and the sun shines through the glass window. Now the sun’s got all sorts of different radiations in it – one we’re very familiar with is the ultra-violet light--that’s the one which makes it all brown and red when we go out into the sun, and also, it’s very good at killing germs. And if there are any bacteria or viruses present in the water, prolonged exposure for 2 or 3 hours to the high intensity ultra-violet light in sunlight, is a very good killer of nearly all germs. And what we find is, we can break the DNA bond, destroy the living matter and the water, of course, has not been heated and the infra-red light from the sun heats the water. So the two different radiation bands – One, the ultra-violet light for killing the germs and Two, the infra-red light for heating the water are combined with this special glass window reflects both these regions of radiation come through it and the end product is hot water. The hot water effectively condenses in this square little tray – there are 32 of these in a typical tray – condenses onto the glass surface where eventually a sheet of water is formed and this whole sheet of water then flows down the inside of the glass and the whole process is called sheeting. And sheeting can only take place, if the mechanism which drives this process is called a heat pipe. So each of these 32 trays consist of a heat pipe and what we have created, (we didn’t know we were doing it,) was an array of square section, short-length heat pipes and because of this totally new principle involved, effectively we’ve been able to double, nearly double what anyone else in the world has produced hithertoward. So we’re quite excited about it, we now understand it. I broadcast it to the world at large at an international conference in Gothenburg in Sweden and I had a queue of nearly 200 people at the stand waiting to look at the poster which proved to be so popular, someone stole the poster, and when I reported it to the authorities they said, “Congratulations Mr Ward, someone wanted it more than you did”.

    Here a link to the abc for the full transcript of the interview.
    https://www.abc.net.au/ra/innovations/st ... 102910.htm
     
  13. Arby

    Arby Junior Member

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    Blackash,

    Thanks for that. Interesting info.

    Arby
     
  14. Michaelangelica

    Michaelangelica Junior Member

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