Talk:Ultraviolet germicidal irradiation

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Article merged: See old talk-pages here and here

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)

Could PeterH kindly consider completing his commentary as this would prove invaluable guidance on design restrictions and considerations to empower interested readers in avoid the oversights he has outlined? I believe much of what he has highlighted can be mitigated through considered integrated systems design once a full understanding of these factors is achieved. If no verification for his assertions is forthcoming, could they be considered as biased opinion?(Tobyvanreenen (talk) 15:57, 13 August 2013 (UTC))

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

EEPROM times

I changed "10's of seconds" to "under a minute." Originally I was going to just fix the "10's" (http://www.grammarbook.com/punctuation/apostro.asp) but that still sounded awkward.

ChrisKurtz (talk) 06:06, 3 December 2009 (UTC)

Merger proposal

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result was merge. -- zazpot (talk) 03:51, 8 August 2011 (UTC)

---

There are two articles with substantially overlapping content. I propose they be merged with this one. zazpot (talk) 22:59, 18 July 2011 (UTC)

For information, since the merge proposal templates will be deleted once the merge is complete, the two articles referred to above are the ones currently present on Wikipedia as Ultraviolet disinfection and UV water disinfection. zazpot (talk) 03:51, 8 August 2011 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Advantages

This paragraph is a mismash of semi-related ideas. UV have nothing to do with making water hard. The boiling does not have to be done on a biomass stove. It is not clear what is meant by chlorine treating "larger organisms." The connection with UV and expensive drill rigs is non-existent. And UV does not make wells "immobile." The advantages section does not really give the advantages of UV. KudzuVine (talk) 13:39, 29 February 2012 (UTC)

"Bandwith" of the 254nm line

This line is a chemical property of the mercury plasma and does not shift or widen with regard to power fluctuations. Article was updated accordingly. — Preceding unsigned comment added by 24.96.249.3 (talk) 20:55, 10 August 2012 (UTC)

Please Add

I wish this article said why reflective linings has the greatest positive effect on the SODIS method. I had figured out that by applying it onto the SODIS method, and testing my water samples. I'm still having trouble finding the answer to my question. — Preceding unsigned comment added by 24.225.121.218 (talk) 21:44, 14 December 2013 (UTC)

reply

I agree with PeterH, this is propaganda. The author just used scientific words. 24.225.121.218 (talk) 16:39, 15 December 2013 (UTC)g

External links modified

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Potential source

• Chatterley, Christie; Linden, Karl (2010-09-01). "Demonstration and evaluation of germicidal UV-LEDs for point-of-use water disinfection". Journal of Water and Health. 8 (3): 479–486. doi:10.2166/wh.2010.124. ISSN 1477-8920.

It's a bit old. Note, "Although research of this technology is still in its infancy, improvements to UV-LEDs are expected to occur rapidly following visible LED source trajectories, resulting in a high efficiency, low input power product." and "Limited research has been conducted on the effective- ness of UV-LEDs for water disinfection" and "Combining projected improvements to power output, lifetime, and cost per mW, results in UV-LEDs being a feasible option and an improvement over LP systems around the year 2013 ( Table 2 )."

Do we have sources showing these projections have been met? --Ronz (talk) 15:29, 15 August 2016 (UTC)

UV irradiation can remove estrogenicity from a water supply?

UV irradiation can remove estrogenicity from a water supply; such estrogenicity may be gained from exposure to EE2, which is overwhelmingly the most common type of synthetic, estrogen used in the contraceptive pill; a woman who takes the contraceptive pill, may excrete EE2 in her urine or feces. According to Zhang, 'Results showed that more than 95% of the estrogenicity was removed after 40 min irradiation and that the parent compound EE2 was mainly responsible for the observed estrogenicity.

This paragraph was initially removed because the source is primary and not relevant to water supplies. Those concerns have not been addressed.

Given the publisher, I'd like some evidence that the source is reliable as well. --Ronz (talk) 19:58, 14 July 2017 (UTC)

• This is kind of misleading. What municipal water supplies actually irradiate their entire water supply for 40 minutes? I don't doubt that in theory, it works, and in relatively small batches, it is effective, but putting it in a section that deals with entire supplies (ie: at least hundreds of thousands or millions of gallons per day), and not just quantities for lab testing, is WP:UNDUE and misleading. If it is included (and I'm not against inclusion if done right), it needs to be qualified better and not framed by paragraphs that talk about entire supplies. This sounds like a small scale theory, not anything that any water supply would use any time soon. Dennis Brown - 2¢ 18:15, 20 July 2017 (UTC)

@Dennis Brown:The paragraph Ronz quoted above was actually changed on 21:41, 11 May 2017‎, by way of response to a comment from another editor who raised similar concerns to yourself. Apparently, Ronz has chosen to ignore the newer version and restate the older version. For what reason I do not know. The newer, edited version was stated in the 'Advantages' section and read:

UV irradiation can remove estrogenicity from water; such estrogenicity may be gained from exposure to EE2, which is overwhelmingly the most common type of synthetic, estrogen used in the contraceptive pill; a woman who takes the contraceptive pill, may excrete EE2 in her urine or feces. In regard to the ability of UV irradiation to remove estrogenicity from an aqueous solution, Zhang states, 'Results showed that more than 95% of the estrogenicity was removed after 40 min irradiation and that the parent compound EE2 was mainly responsible for the observed estrogenicity.<ref>

• • Still, that isn't practical for a "water supply". I'm not sure it needs to be in there at all, and in fact, would say it is misleading. No water supply irradiates for 40 minutes. That was and still is my point. Dennis Brown - 2¢ 17:33, 31 July 2017 (UTC)

@Dennis Brown:I am not applying the statement to a water supply. Do you mean that the 'Strengths' and 'Weaknesses' sections are only for water supplies and not for other uses (boiling is also discussed there)? If that is the case, then perhaps a solution may be putting it in a different section.RickyBennison (talk) 15:20, 1 August 2017 (UTC)

It was right under a paragraph discussing water supplies so it was implied that removal is an option for water supplies. It is not. I think before you put it in at all, I think you first need to explain why it is helpful in an article that covers "Ultraviolet germicidal irradiation" (and is in fact named that), then we can talk where it would go. Estrogen is not a germ, or any other kind of living organism. I'm not convinced it belongs anywhere in this article, although I'm open to hearing why it does belong. I think that is why you keep getting reverted. Again, I really am open to hearing, but at first glance, it appears to be well out of scope for this article, no matter where you put it. Dennis Brown - 2¢ 15:31, 1 August 2017 (UTC)

I don't see a solution without finding some non-primary sources that put this type of research into context which we can then follow. --Ronz (talk) 15:47, 1 August 2017 (UTC)

• I agree that a non-primary source is needed, but even then, why is this important in an article about "germicidal irradiation"? That still doesn't fix the scope issues. Dennis Brown - 2¢ 18:37, 1 August 2017 (UTC)

I agree. The new source would have to establish the link between the topic of this article and the topic of the research. --Ronz (talk) 19:23, 1 August 2017 (UTC)

Hi, sorry for late reply. I acknowledge the scope issues. An argument for including it in this article may be that the removal of EE2 constitutes the removal of an environmental contaminant- and that this removal and disinfection may both be achieved as part of the same overall process which utilises UV irradiation i.e. one process involving UV irradiation both cleans environmental contaminants and disinfects. I am by no means an expert but I think some AOP processes are an example of this. So to add the previous to this article, in more general terms which are non-specific to EE2 (because I have not seen any direct references to AOP and EE2 yet), perhaps a short section along the lines of 'UV germicidal irradiation is sometimes achieved via AOPs, some of which are also used to clean environmental contaminants.' Perhaps the section could be called 'Usage of UV irradiation technology in other processes to both disinfect and clean environmental contaminants/perform other functions.' I am by no means insisting on this, but I thought it was worth putting forward as an idea.RickyBennison (talk) 16:55, 14 August 2017 (UTC)