Kai, the UV sterilizers tend to be small units - you need a great many of them for larger flow rates (at least that's the type I'm familiar with -- there may be others designed specifically for very large installations....).
A web search for "UV sterilizer" will get you thousands of links.
Here's what one of them says:
http://www.aquascience.net/uv.htm#uv
A UV water treatment system is relatively simple in design. Source water flows into a closed chamber with a UV lamp in the center of the chamber. The flow rate through the chamber must allow all the water to be exposed to the UV light. High turbidity in water can block light or hide microbes. Dissolved substances such as iron, manganese, organic carbon, and nitrates will increase the absorbance of the UV radiation by the source water, thus reducing the delivered UV dose. Pretreatment to reduce the concentration of these compounds may be necessary to optimize the performance of the UV system.
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Another advantage you didn't mention is that the gamma sterilizer doesn't need lamp changes like the UV version.
Nonetheless, I think that all these advantages are far outweighed by the high cost of a gamma sterilizer.
Jaro
-----Original Message-----
From: Kai Kaletsch [mailto:info@eic.nu]
Sent: Friday July 05, 2002 9:35 AM
To: Franta, Jaroslav; RadSafe
Subject: Re: Water Irradiation?
Both gamma and UV irradiators have to be on 100% of the time because, unlike chlorine, they do not kill downstream of your unit and any bugs that get by are home free. If UV irradiators need power to run, then they also need backup power and an operator 24/7 who knows how to run the system.
How do you deliver the UV? It doesn't go through a steel pipe. If the water needs to be open to the atmosphere, that brings some more challenges.
There are some advantages to passive systems.
Kai
----- Original Message -----
From: Franta, Jaroslav
To: Kai Kaletsch ; RadSafe
Sent: Friday, July 05, 2002 7:22 AM
Subject: RE: Water Irradiation?
That's an interesting idea, but I'm pretty sure its impractical from the economic point of view, since such an irradiator would have to compete with a variety of commercial UV sterilizers of all sizes already on the market.
The one advantage a gamma sterilizer would have over a UV one is that the water would not need to be clean for the former to be effective -- UV sterilizers typically have reduced effectiveness in turbid water, as the bugs are shielded by bits of dirt.
Jaro
----- Original Message -----
From: Kai Kaletsch
To: RadSafe
Sent: Thursday, July 04, 2002 9:07 PM
Subject: Water Irradiation?
Not sure how aware the rest of the world is about this, but here in Canada there have been some issues with people getting sick or dying from bugs in the drinking water over the last couple of years. Water treatment has been a municipal issue but now the feds and provinces are getting more involved.
Some communities absolutely refuse to chlorinate their water. I was wondering if anyone knew what kind of dose it would take to kill the bugs in the water. Could that be achieved by putting some Cs-137 or Co-60 next to a water pipe? Would it cause the pipe to fall apart? Any side effects to the water?
I would just love to see someone propose that to one of these communities:)
Kai