Science Forums 2

[Turtle]

Originally Posted by freeztar

I'm unable to find studies related to UV effectiveness, can you please provide some sources?

i found some stuff.

Ultraviolet - Wikipedia, the free encyclopedia

The Sun emits ultraviolet radiation in the UVA, UVB, and UVC bands, but because of absorption in the atmosphere's ozone layer, 98.7% of the ultraviolet radiation that reaches the Earth's surface is UVA. (Some of the UVB and UVC radiation is responsible for the generation of the ozone layer.)

Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths while Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm.[4][5][6] ...

Ultraviolet Water Sterilization | BuyUV.com

Ultraviolet radiation is a type of light, unlike visible light, that cannot be seen. Its wavelengths, expressed in Angstrom units (one Angstrom unit wavelength equals one hundred-millionth of a centimeter), are shorter than the wavelengths of visible light and carry more energy. Because of this high concentration of energy, UV radiation has the unique ability to kill microorganisms with which it comes in contact.

HOW DOES ULTRAVIOLET RADIATION WORK?

Ultraviolet radiation sterilizes water. Sterilization implies that life such as bacteria, viruses, yeasts, molds, and algae are destroyed. For UV radiation to work, a 2537 Angstrom unit (254 nanometers) wavelength must come in contact with the microorganism to inactivate it. When ultraviolet rays reach the microorganism, they strike the heart of the organism destroying the DNA (deoxyribonucleic acid) and preventing it from reproducing. Table I give the amount of UV necessary to kill various microorganisms.

a list of some 'germs' and the UV dose needed to kill them: >> Germicidal Disinfection Information

Originally Posted by lemit

This is fascinating.

I've had giardia. I went for two months before I got it diagnosed. It isn't fun and I wouldn't recommend it, but I've had worse.

Where I grew up, we had water from a deep well about a half mile from a coal vein. It stuck to your ribs and probably provided more than the daily requirements of a lot of mineral supplements.

Speaking of where I grew up, if you aren't trying to make a hip-pocket purifier, how about a still like some folks back there had? Wouldn't that do the job?

That isn't a leading question. I don't know much about purifying. I wish I had when I was drinking that oily stuff.

--lemit

a still is ideal. for my hip-pocket needs, well, rucksack, i'm currently using a fiber/charcoal filter unit, and i carry a little bottle of bleach too. as it is, it would be a rare thing for me these days to take an adventure without taking all the water i need.