Flow measurement in sludge treatment at a sewage treatment works in southern England

A Katronic employee assisted partner Z-Tech in the south of England with the commissioning of six KATflow 150 flowmeters at a wastewater treatment plant. The aim of the project was to measure the flow rate of activated sludge and excess sludge in 16 grey cast iron pipes. To this end, the first Katronic flowmeters fitted with Profibus PA modules were supplied to the UK via ABB. The installation was carried out in compliance with all prescribed spacing and safety regulations, for which Katronic was specifically classified and approved as a ‘system-relevant supplier’ for this project.

Monitoring activated sludge and excess sludge is important for maintaining a constant biomass concentration, which is why precise and repeatable flow measurements are of central importance in sludge treatment. The 16 grey cast iron pipes, with diameters ranging from 80 to 440 mm, were laid between 1930 and 1950. Measurements were complicated by sludge deposits inside the pipes, so the portable KATflow 210 and KATflow 230 flowmeters were used beforehand to record measurement values during a 24-hour test, which demonstrated the reliability of the measurements.

During the main installation of the six stationary KATflow 150 flow meters, the sensors were each mounted on the pipe at a distance of approximately 50 m from the measuring unit. Katronic’s ‘Acoustic Sensor Positioning Assistant’ helps to determine the correct sensor positioning when the control unit is out of sight but within earshot. For this installation, the Katronic Positioning Assistant attached to a portable KATflow 200 flow meter was used, which enabled the sensors to be set up on the pipe in advance before they were connected to the main control unit. The Katronic employee also configured the Profibus PA cards in each measuring device so that they could be successfully connected to the plant’s control system.