Primary Settlement Tanks Sludge Level Measurement

Welsh Water approached us to help them find a solution to automate the de-sluging process of their primary settlement tanks. Automation was require to reduce down time and maintenance costs, high sludge levels were causing damage to the scrapers resulting in expensive replacement parts to be source from the USA and up to 3 days down time to drain the tanks, clean and repair. Secondly with an automated de sluding process the output percentage solids constancy of the sludge can be control to a far greater tolerance allowing the whole pant process to run more efficiently.

Application Problem

The challenge faced with this application was the varying levels of suspended solids within in the sludge ranging between 0.5 and 5%. The large variation would make it challenging to track the sludge blanket level accurately. This particular tank also had no surface rakes meaning thick layers of scum could form potentially obscuring the the sensor face.

Solution

From previous experience with sludge bed level measurement Hawk was able to recommend the use of the Sultan Sonar continuous bed level transmitter. Thick surface scum was no problem for the Hawks unique Sonar level transmitter, its high power sensor face constantly vibrating aids self cleaning while the full fibre glass housing meant the transducer could be submersed below the surface scum.

Calibration of the unit was performed over the course of a morning and two de-sluding pump cycles against the their current Partech Sludge Watch measurement device to insure accurate tracking of the sludge level.

The unit was trailed for 1 month against the current manual Partech Sludge Watch device. Using Field Electronics IOT interface the Sultan Sonar could be monitored live on a web based dashboard to keep a log of sludge level and calibration parameters could be adjusted live over the air if required.

Daily site reports over the trail period recorded the Hawk Sultan Sonar Level measurement Vs the Partech Sludge Watch and the current percentage solid levels. Through out the trial period the Hawk Sultan Sonar continued to give an accurate bed level measurement even with the suspended solids percentage varying constantly in the range of 0.83% to 3.2%