Talk:Ultraviolet germicidal irradiation

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Did You Know An entry from Ultraviolet germicidal irradiation appeared on Wikipedia's Main Page in the Did you know? column on 12 September 2006.
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As someone that moved from England to Sweden (in 1988) I noticed how much nicer the water tastes here. It was only after working in a number of water works here that I discovered that we use UV rather than clorine to purify the water. Clorine is available as a stand by if the UV systems fail.

One aspect is that since the clorine stays in the water, it stays as sterile all the way to the tap (and into your body) whereas UV treated water can become reinfected.

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[edit] Propaganda

This article is mere propaganda, and does not deserve to be on Wikipedia's Main Page. UV's main drawback is its lack of a residual, meaning that any germ that by chance survives the radiation, can begin to reproduce happily in the piping system once this single hurdle of UV radiation is taken. The odds of survival are in fact quite high, because the radiation intensity decreases exponentially an a straight path, being further attenuated fpr spatial reasons (radial rather than parallel light beams), so that many commercial systems contain lines through which germs could theoretically pass rather unharmed. In fact, I have seen commercial systems where after the UV system the germ count was higher than before, owing to biofilm development at the exit parts that are not exposed to radiation, and where because of tha lack of a residual, there is no disinfection at all. In addition, "real" water contains lots of material that can scatter light, further attenuating UV intensity. Because of Rayleigh's scattering law (scattering depends on wavelength to the fourth power!!!), the popular absorbance measurements to determine UV teatability are just window dressing, and not based on thorough science. To make things worse, UV destroys all common chemicals that may have been used prior to the water being irradiated. The biased praise of UV in this article is unwarranted. (PeterH, 2006-09-12)

If you can verify your arguments, why don't you add them to the article? Melchoir 16:09, 12 September 2006 (UTC)
With pleasure, as soon as I have time, but right now I am preparing for a job where the health officer has shut down a UV system because it has contaminated a previously clean hospital piping system, as I predicted, for exactly the reasons outlined above. This and some other similar jobs will keep me busy over the next few weeks, so please bear with me. (PeterH 2006-09-12)

[edit] hey! Collagen is now a cell?

I was reading this article after it was featured on the main page, and I spotted the following:

When this happens a person’s cells such as collagen are damaged at the cellular level.

I believe that collagen is a protein in skin rather that an actual cell. Just thought I'd point that out... it doesn't detract from the article much.

Alpineflame 13:09, 12 September 2006 (UTC)AlpineFlame

Well, feel free to fix it; this is Wikipedia, after all! Melchoir 15:53, 12 September 2006 (UTC)

I removed the 'cells like collagen' and added a bit about thymine dimers... but as an amateur biologist at best I will need to research further to thoroughly fis the 'How UVGI works' section.

[edit] Propaganda Redux:

As the author of this let me state for the record: I wrote this based on an article I read in regards to ultraviolet used to remove allergens from circulating air. I wanted to check the article against Wiki and was surprised there was limited information about it in the Ultraviolet section. I had no agenda and I certainly don't advocate it. Just being bold. Please update the article with any information that corrects my errors. -- PDream

[edit] What about?....small, acid-soluble proteins

I am writing a paper about an iodine disinfection mechanism, and I wanted to find a better definition for small, acid-soluble proteins, which apparently limit UV's disinfection capability with regard to endospores. At least according to this paper, whose references, (Popham et al., 1995, Tennen et al., 2000) I don't have in front of me. But the only wikipedia article to mention small, acid-soluble proteins is in german. I'm not a biology/biochemistry major, so I'd rather not get it all wrong, but if someone can expand on this, many perplexed students besides myself will benefit. User:wysockat 20:24, 12 December 2006 (UTC)