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Sunlight Sterilization of Water


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I have read them turtle, when they say UV sterilization they are not talking about the UV in sunlight, they are talking about the UV from a germicidal lamp. Huge difference! I have built several UV sterilizers for my own use and for commercial use, even with germicidal lamps it is difficult to do, the water must be filtered so no particles bigger than the organisms is in the water. It still takes time to kill bacteria, protozoans are harder to kill and require much more time. A germicidal lamp can blind you fairly quickly, it can kill you, burn you severely, UV we get on the surface of the earth is not any were close to being as strongly germicidal. I see no way to use the UV in sunlight to sterilize water from a non-potable source.

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In addition to just painting it black, you can get much higher temps with the same amount of sunlight by increasing the pressure inside the glass. Granted, this may very well be beyond what Turtle wa

I think that info should give an idea if whether your UltraViolet Portable Absorption Sterilizing System (UV-PASS :)) should work.   According to the chart you link, bacteria need between 3620 and 220

I have read them turtle, when they say UV sterilization they are not talking about the UV in sunlight, ....

 

erhm...uh...post #4

Step 4 Utilize the effect of ultraviolet radiation on the most common pathogens. This is of particular use if you are in a circumstance where large amounts of sterile water are needed and you have few resources. Pour off particle matter. Take the clear water and pour it into a clear plastic bottle. Place the plastic bottle on a dark surface. Leave the bottle in sunlight for at least eight hours. The combined effect of ultraviolet radiation from sunlight and heat is effective in producing a primarily safe source of drinking water.

 

:) B)

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A germicidal lamp can blind you fairly quickly, it can kill you, burn you severely, UV we get on the surface of the earth is not any were close to being as strongly germicidal.

 

Well, focusing sunlight through a 3 inch lens could blind you quicker than a UV lamp (or burn you quicker). But, I think you have a sound point. There's a big difference between the UV-A which reaches Earth's surface and the optimum (middle) 254 nm for killing little buggers. The other day when I was writing the post above I found a source saying about 5 µW/cm2 of UV-B reachs the surface. I've lost the link now, but if true, that is not enough in-and-of-itself to do any real damage with a moderately-sized lens.

 

The real question then, is how well UV-A works as a germicide. I don't know. If it's even half as effective as the middle range of UV frequencies then I believe Turtle's idea could work very well.

 

~modest

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I have used the SteriPEN with no regrets. It uses UV-C.

 

# Ultraviolet (UV-C) light rays safely sterilize clear water by destroying 99.99% of protozoa (including Giardia and Cryptosporidium), bacteria and even viruses

# SteriPEN protects you from risks that cause botulism, cholera, dysentery and typhoid, just to name a few

SteriPEN Adventurer Water Purifier at REI.com

 

The biggest problem I see is having enough UV-C to destroy Cryptosporidium cysts. Nasty stuff it is. :)

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I didn't know that UV-C was required to kill microbes, but I have learned that very short wavelength UV is almost completely blocked by our atmosphere.

 

Turtle, you posted a link earlier about disinfecting water using the sun. Here's a wiki page I found giving more info. Apparently UV-A can be effectively used to kill microbes, but it requires a long exposure and is aided by higher temperatures.

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Turtle, you posted a link earlier about disinfecting water using the sun. Here's a wiki page I found giving more info. Apparently UV-A can be effectively used to kill microbes, but it requires a long exposure and is aided by higher temperatures.

 

indeed. so the old question remains, does a 'magnifying' lens, of any material whatsoever, bend any range of UV radiation whatsoever, to a focus as they do visible light? i have asked 3 times & looked on my own 4 times & still have nada. :Alien: no speculations thank you; just the physics phacts Mam.

 

now in light (:( ) of your wiki and my original article, the new question is how significant a factor is the volume of water being treated with Sunlight to the amount of time necessary? which is to say will a larger bottle of PET plastic containing contaminated water take longer than a smaller bottle to sterilize when place out in the Sun? again, the physics please. :hihi:

 

also, since the water is largely transparent, won't any particles, spores, protozoa and the like absorb the other light frequencies that do come to a focus? won't that fry them?

 

i may make a little experimental stand and try my hand at blazing some water drops. i have access to a 4 or 5 inch magnifying glass. :clue: ants be forewarned. :eek: :hihi:

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If focusing of UV is your desire, you might wish to explore the technology of UV irradiators as your guide.

 

UV Irradiators

Ultra-Cure UV Systems from Hernon Manufacturing, Inc.

 

 

Specific to sanitation and sterilization: UV sterilization and sanitation control.(Product focus: Sterilization and decontamination products)(Brief article) | Article from Medical Laboratory Observer | HighBeam Research

 

 

Wishing you well in you technoengineering creations, Turtle. :(

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indeed. so the old question remains, does a 'magnifying' lens, of any material whatsoever, bend any range of UV radiation whatsoever, to a focus as they do visible light?

 

Yes. But, the focal point might not be the same as for visible light. Quarts is recomended for imaging UV: Lenses for industrial applications-standard and custom lens design from Universe Kogaku

 

This chart shows the typical transmission of the Universe family of quartz lenses. Though they are optimized for 266nm you can see the wide range of transmission. Be advised that the lenses are NOT corrected for constant focus throughout this range. Re-focus will be required at different wavelengths.

 

I wonder what a good sized quartz lens would cost. You might be better off with a parabolic mirror, which I think Infinitenow's links use.

 

~modest

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If focusing of UV is your desire, you might wish to explore the technology of UV irradiators as your guide.

 

UV Irradiators...

Wishing you well in you technoengineering creations, Turtle. :([/

 

interesting. :hihi: one problem with using a lens, UV aside, is that it has to be moved continuously to follow the Sun and keep the focus, and that did put me to thinking of a parabolic reflector as i used for my experimental parabolic trough charcoal oven, because it only needs aligned E/W to work. :clue:

 

more interesting then with your link is that they indicate that a parabolic reflector diffuses the UV, and an eliptical reflector focuses it. :Alien: mmmmm....

 

it's late & will get to rest of links tomorrow. thnx. :hihi:

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so the old question remains, does a 'magnifying' lens, of any material whatsoever, bend any range of UV radiation whatsoever, to a focus as they do visible light?
Yes. But, the focal point might not be the same as for visible light. Quartz is recomended for imaging UV: Lenses for industrial applications-standard and custom lens design from Universe Kogaku

 

they say of their UV lenses:

Though they are optimized for 266nm you can see the wide range of transmission. Be advised that the lenses are NOT corrected for constant focus throughout this range. Re-focus will be required at different wavelengths

 

refocus necessary; check. :eek_big:

 

I wonder what a good sized quartz lens would cost. You might be better off with a parabolic mirror, which I think Infinitenow's links use.

 

~modest

 

the only site i found that looked promising for finding a quartz lens price required registering. :clue: roger the parabolic reflector. i realized this morning that the reason the folks at In's link were using an eliptical reflector rather than parabolic is that the UV light source is at the focus, whereas for our business it is the water that is at the focus.

 

so if we put a bottle of contaminated water in a parabolic trough reflector, sterilization would be quicker than the bottle just sitting out in the Sun as previously described as effective sterilization, oui/no?

 

still wanting to know what part does the volume of the water treated play in the amount of time necessary for sterilization? :shrug:

 

still looking for that big hand lens to try & fry some agua. :confused:

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so if we put a bottle of contaminated water in a parabolic trough reflector, sterilization would be quicker than the bottle just sitting out in the Sun as previously described as effective sterilization, oui/no?

 

Oui. Much like SEGS :)

 

Do you have a post or a pic you can point me to with the parabolic trough from your charcoal oven? You've piqued my interest with that, and I think I was not yet a member when you were working on it :doh:

 

still wanting to know what part does the volume of the water treated play in the amount of time necessary for sterilization? :agree:

 

Water is very transparent to UV. The sputum at the bottom of this page shows the absorption coefficient. UV is light blue. So, the volume would not really matter in that respect. However, I would think you'd want to focus the light on as small a target as possible ruling out a very thick tube with a large cross section...

 

More than that... I guess the flow rate would depend on the luminosity on the target. Here's a source that talks a bit about it.

 

An exact flow rate as a function of luminosity I cannot find and wouldn't know how to calculate without more info. Sorry.

 

~modest

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Oui. Much like SEGS :agree:

 

Do you have a post or a pic you can point me to with the parabolic trough from your charcoal oven? You've piqued my interest with that, and I think I was not yet a member when you were working on it :(

 

but of course. :)

 

Sun! Very sunny day. I put the oven out about 40 minutes ago & it is now at 180 deg F. Just air inside (and an oven thermometer) so far. Photo below. WARNING! Do NOT look directly into the reflector!:lol: :phones:

 

 

Water is very transparent to UV. The sputum at the bottom of this page shows the absorption coefficient. UV is light blue. So, the volume would not really matter in that respect. However, I would think you'd want to focus the light on as small a target as possible ruling out a very thick tube with a large cross section...

 

More than that... I guess the flow rate would depend on the luminosity on the target. Here's a source that talks a bit about it.

 

An exact flow rate as a function of luminosity I cannot find and wouldn't know how to calculate without more info. Sorry.

 

~modest

 

roger all. this brings us from the push to the shove, which is to say experiments. i have searched high & low for the big magnifying glass i mentioned earlier, and all so far for naught. :( no skin off my cheeks today though as it is raining. :rain::rainumbrella:

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Do you have a post or a pic you can point me to with the parabolic trough from your charcoal oven? You've piqued my interest with that, and I think I was not yet a member when you were working on it

 

http://hypography.com/forums/science-projects-and-homework/6465-solar-parabolic-trough-charcoal-oven.html

 

Posts 21 and 187 at the link above...

 

...With an interesting video from someone else in #259, and another interesting design in #289.

 

 

 

EDIT: Damnit! Got ninja'd by the Turtle himself. :rainumbrella:

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