Sunlight Sterilization of Water

[freeztar]

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.

[modest]

Yeah, I think UV-C works brilliantly.

I'm having the hardest time finding any kind of source saying just how germicidal UV-A is.

~modest

[Moontanman]

Good luck getting UVC from sunlight on the surface of the Earth.....

[Mercedes Benzene]

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.

[Turtle]

Originally Posted by Mercedes Benzene

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. 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.

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. ants be forewarned.

[InfiniteNow]

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.

[modest]

Originally Posted by Turtle

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

[Turtle]

Originally Posted by InfiniteNow

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. 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.

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

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

[Turtle]

Originally Posted by modest

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.

Originally Posted by Modert

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. 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?

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

[modest]

Originally Posted by Turtle

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

Originally Posted by Turtle

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

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