HDPE and PE concrete protection for treatment plants.

H2S gases are released during the biological treatment process of a sewage treatment plant. This is also the case with the process at the Echten WWTP. H₂S-gases can affect concrete so quickly that it rots away within a few years. To prevent this, DL Plastics is providing the five concrete tanks at the WWTP in Echten with a special lining.

A sewage treatment plant holds no secrets for DL Plastics. "We have been to every sewage treatment plant in the Netherlands at one time or another, to one degree or another," begins Ronald de Lange who has been active in the family business all his life. For more than 50 years, DL Plastics has been a major player in the world market in the processing and assembly of flexible films in various sectors. "We are right at home at sewage treatment plants, WWTPs and industrial wastewater treatment plants and have a solution for every exception situation." 

Many variants

DL Plastics is also a familiar relationship for Van Hattum and Blankevoort. "They always know how to find us for these types of projects," says Ronald. "Internally, we looked at the request and proposed a solution. In Echten, we chose different types of concrete protection in HDPE and PP. The latter can withstand higher temperatures. We also distinguish between our DL T-lining for new construction and the DL Renovation Lining for existing tanks that is not cast in but mechanically fastened. All of these variants are covered here." The existing tanks at the WWTP in Echten will be fitted with a roof. "Previously, gases could escape freely here, but since everything is now covered, it is crucial to properly protect the concrete above the water line. We therefore connect to the existing materials and can weld them together one on one."

Pressure on implementation

The DL Renovation Lining is assembled by DL Plastics itself, while the DL T-lining is custom-made and put on the formwork by Van Hattum en Blankevoort itself. "Naturally, everything is welded and tested by us on site," assures Robert Rouhof of DL Plastics. "All corners and penetrations are also finished so that every crack and seam is guaranteed to be sealed." One tank has now been completed; the remaining four are scheduled for next year. "The biggest challenge is mainly in the weather. Plastic welding requires temperatures above 5 degrees Celsius and dry weather. In addition, our work always takes place immediately after the concrete work and before the finishing work begins. So there is always pressure on execution, but we are entrusted with that. And because we operate in multiple sectors, we can quickly step in and add people if necessary."

In total, DL Plastics processes some 2,000 m2 of concrete protection at the WWTP in Echten. "In addition to the five tanks, we also provide a number of small sand collection pits and a grate with concrete protection."