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Rights: The University of Waikato
Published 29 July 2008

Sanjay Kumarasingham (Watercare Services Ltd) talks about the ideal conditions for disinfecting wastewater effluent.

UV Comparisons/Emperor Aquatics


What are the right conditions for the water to get to ultraviolet disinfection? Generally, you would need to have water of a good quality – so it should very clear, so the water rays of the 254 nanometre UV wavelengths penetrate through the entire water surface, so any bugs that are within the water particles as it moves through actually get zapped. So when you look at the influent to the UV plant, it is very clear, and the clarity is required to pretty much have the penetration of the UV rays onto the microbial cells. By sight, you won’t be able to see it – you will need a microscope to have a look at the bugs. And that is what we are trying to attack. There is a need, obviously, for a certain exposure period, when the water is moving across the UV channel. So the lamps are stationary, the water is moving through, and the period that the water is moving through is controlled by an inlet and outlet pinstock.