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Topic: UV disinfection in water treatment  (Read 2679 times)

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Offline Civilwaters

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UV disinfection in water treatment
« on: April 19, 2010, 08:37:06 AM »
I am designing a UV disinfection unit

I need to ensure an internal intensity/dose of 410 J/m.sq to all waters that pass though. (to comply with WHO guidelines)

I am aware of The Beer-Lambert Law but will have no data on absorption apart from turbidity in NTU's. Is there any conversion or link up?

The text books I have looked at have the photon output and as such energy within the tank but not intensity. (they are dealing with oxidation of chemicals and not inactivation of cells)

Any recommendations (ideas, online reading etc)

or am I just going to have to over design with a intensity sensor on the outer casing and power control system.
(humm going to need at least an ball park idea to do the over design)

Offline marquis

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Re: UV disinfection in water treatment
« Reply #1 on: April 20, 2010, 07:08:07 PM »
Sorry, I'm not familiar with that type of ozonation.  Could I impose on you for some background information?  How is the ozone monitored?

Beers Lambert is usually used in spectrometry.  This typically measures the amount of light passing through a sample.

You are using nephlometry.  This measures the amount of light reflected (usually from suspended particles) at a ninety degree angle from the beam.  It's a different type of measurement.  Depending on your application, Beers Lambert might not apply.

Offline eugenedakin

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Re: UV disinfection in water treatment
« Reply #2 on: April 25, 2010, 08:02:21 AM »
Hi Civilwaters,

Very good question. Unfortunately, I am going t sound like a lawyer when answering your question, as the answer is 'it depends'.

Yes, you definately will need to over build the amount of UV treatment. Maximize the time and intensity for UV exposure.

The reason why this will need to be overbuilt is that there will always be upsets in the plant (unintentional, and intentional). These upsets will always cause 'caking' and dirtying of the UV tube(s), which will decrease the effectiveness of the treatment.

NTU's is the standardized measurement, and is a pretty good method for translucence.  I would try and use this type of data for quality control.

As far as information is concerned, keep looking up more information from WHO. There are many books on Water and Wastewater treatments that will be able to help you with design parameters.

Best wishes,

There are 10 kinds of people in this world: Those who understand binary, and those that do not.

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