Flow Measurement for UV Channel

Accurate and Reliable Non-contacting Open Channel Flow Measurement for Sewage Treatment Works in Hong Kong.

The Sai Kung Sewage Treatment Works in Hong Kong is a secondary sewage treatment works that supplies sewage treatment services to a population of 20,000 in the Sai Jung District. The plant includes two primary sedimentation tanks, two aeration tanks, two final settlement tanks, an ultra-violet disinfection system, and sludge treatment facilities.

Engineers at the treatment works were having issues with a low flow velocity of 0.05-0.1 m/s in their UV channel. Accurately knowing the amount of water that is flowing through this stage of the treatment process helps control the UV intensity of the effluent flow over the exit flumes.

For this application, it was decided that a non-contacting area-velocity solution would be best. A non-contacting open channel flow solution does not come into contact with the measurement medium, therefore cannot contaminate already treated water, and does not require maintenance due to wear and tear. Additionally, there were no system shutdown costs or complications as the sesnros are installed above the measurement medium.

The dBMACH3, MicroFlow, and FlowCERT system is a complete non-contacting area-velocity solution, the dBMACH3 measures the level of the channel, and the MicroFlow measures the surface velocity of the flowing liquid. Both readings return to the FlowCERT controller, which performs calculations to supply a localized reading of flow.