Fat turns out to be no problem for the system

Apilot is intended to demonstrate that something works, even in the everyday practice. At the beginning of November, the ICABUS was installed at the wastewater treatment plant (WWTP) in Olburgen, operated by Waterschap Rijn en IJssel. The system has worked perfectly without any malfunctions, except for one minor issue.

The photo shows a lump of fat. This lump was found in the 20-meter-long hose that returns the pulp to the supply of the primary settling tank. As a result, the hose would occasionally become clogged, causing a nasty mess. However, note that the ICABUS has successfully separated the fat without any issues, so fat turns out to be no problem for the system.

My working hypothesis was that an illegal discharger was dumping their grease trap into the sewer in the evening hours (since that was when the problems occurred).

We use an immersion pump. The pump is installed after the overflow of the sand trap and is in direct connection with the primary settling tanks.

“This weekend, almost at the end of the tests, I finally took the time to think carefully and systematically about the cause of this. And I think I finally know how this problem is occurring. The pump controls the water level. With a low input flow (evening and night), the pump will allow the water level in the primary settling tank to drop, causing backflow from the primary settling tank to the channel where the pump is located. In this process, coagulated fat will also be returned (the primary settling tank is also the grease trap). If the fat lump is large enough and the water level low enough, the fat lump will be sucked in and carried to the ICABUS. The fat is properly separated but ends up in the pulp pump hose, where it causes problems.

Lessons learned:
1) The ICABUS can handle fat very well
2) Fat is hoses can cause blockages
3) Think carefully about the potential risks (in a HAZOP, this falls under the category ‘reverse’)
4) Cleaning up sprayed used toilet paper is not a pleasant task

Bron: https://www.linkedin.com/posts/fransdurieux_vet-en-de-icabus-een-pilot-dient-ervoor