Long-term proof: Combination screens have been running trouble-free for 19 years

19 years of trouble-free operation – combined screens protect membrane sewage treatment plant

The planning and tendering process for the construction of the Bronn an der Pegnitz membrane sewage treatment plant began back in 2004. A central task was to reliably protect the hollow fiber membranes from solids in the wastewater. Efficient and reliable pre-treatment was therefore crucial for the long-term operation of the plant.

After careful consideration, we opted for a solution from nrw Anlagentechnik. The system was completed and put into operation at the end of 2007. Since then, the installed contec combi rakes have been performing reliably – and have now been in continuous operation for 19 years.

A so-called twin installation with two combination rakes working in parallel is used. The entire system therefore has two cleaning stages. Each of the two screens has a two-stage design: In the first stage, a 3.0 mm perforated screen ensures coarse separation. In the second stage, a fine screen with a 1.5 mm perforated screen cleans the wastewater further. This multi-stage system reliably removes screenings, hair and fibers before the water reaches the membrane stage.

The long-term effect is particularly evident today. After 19 years of operation, the hollow fiber membranes are still reliably in use and have clearly exceeded their originally predicted service life.

Based on this positive experience, we have now also equipped two other wastewater treatment plants with nrw contec screens. The systems are also working reliably there and are contributing to stable and economical operation.

Dominik Schauer, Wastewater Treatment Plant Manager
City of Pegnitz