Rights: The University of Waikato Published 29 July 2008 Download

Sanjay Kumarasingham (Watercare Services Ltd) talks about what conditions are monitored in order to maintain the UV disinfection process.


The UV plant is basically getting effluent from the secondary treatment process, so if the secondary treatment carries suspended solids, it basically forms a film on the lamps itself. So there is a sleeve which goes across, and it is cleaning the lamps to have optimum rays coming out. The plant is monitored every day. We are trying to target a certain dose at which we know that the microbial organisms are dead. And the other thing that we do is monitor the UV intensity, and if the intensity starts falling below a certain level, we replace the lamps, and this happens after 12,000 hours of working. We tend to not replace them every day, but we tend to replace an entire channel every so often. When a channel is in service, we know the run of it, so what are we monitoring for maintenance purposes would be the run hours on the channel. That is the classic indication of how long it would last and what we need to do to bring it back on line. We clean the channels as well, along with the wiping system – there is a physical process of hosing the channels off, hosing the lamps off to keep it clean.