Dunea successfully remove mussel seed via Huberts micro-filters

Drinking water company Dunea produces and supplies drinking water to approximately 1.3 million customers in the western part of South Holland. One of the water treatment plants, is low pressure pumping station Brakel. Here, surface water is collected to be purified into drinking water.

The surface water of the Afgedamde Maas contains large quantities of mussel seed. This is causing problems in Dunea’s cooling water channels and installation parts. The mussel seeds grow into mussels resulting in damage and excessive wear. The Hubert micro-filters, with a total capacity of about 12,000 M3/hour, are placed at the pumping station to filter the dirt and mussel seeds out of the water.

Wear and tear of the bearings

The conditions in which the micro-filters operate are harsh. Sand and shell particles penetrate into the installation, resulting in wear and tear. This was particularly the case with the bearing construction of the micro-filter. In consultation with Dunea, it was therefore decided to investigate whether the lifetime of the bearings could be improved. In addition to cost savings in maintenance, this would also certainly increase the operational reliability of the installations.

In May 2015, the improvement project for the micro-filters started. The central question with regard to the bearings was: ‘What is causing the wear and tear and how can we minimize it?‘  In order to be able to answer this question properly, (online) studies were carried out of similar situations and discussions were held with experts and suppliers. The experiences of other customers, who also use the micro-filter, proved to be very valuable and indispensable during this process.

Research into the existing micro-filter installations quickly showed that no demonstrable cause could be found beforehand. The applications and conditions of the installations varied so much that no conclusions could be drawn. Possible causes; corrosion, contamination, wear of the materials used and combinations of several factors. 

Gaining experience

Testing under similar conditions proved to be the best solution.  In 2017 and 2018, several constructions with various (stainless) material types and seals were tested. From the tests and research, it was suspected that the wear resistance of the materials used was insufficient due to contamination. It was then decided to increase the wear resistance of the bearing construction. The challenge here is the choice of material and its implementation in the existing construction.

Usually the wear resistance of a material comes at the expense of corrosion resistance and Water Alliance member Hubert wanted both! In consultation with Sietzema Techniek a wear-resistant coating was chosen. The advantage of this is that the existing (stainless) steel construction does not need to be changed.


By hardening the wear parts and choosing the right counter materials, the wear is minimal. The modified seal also prevents contamination of the bearing and ensures an effective seal of the micro-filter. The end result; the Hubert micro-filter is a robust and reliable installation that can be used with minimal maintenance in numerous applications in the field of micro-filtration. Meanwhile, this renewed construction with the coating of Sietzema Techniek, is already used for several projects.

Source: Hubert