First ozonation plant for advanced wastewater treatment in the Netherlands: HUBER supplies stainless steel equipment for Houten wastewater treatment plant

It is an ideal location for advanced wastewater treatment: HUBER, through its Dutch representative Dutch Spiral B.V., supplies proven stainless steel equipment from its Safe Access Solutions (SAS) business unit for the Netherlands' first wastewater ozonation plant. The scope of supply includes five HUBER Access Covers TT8a and three HUBER Pressure-Tight Doors TT7. 

Dutch drinking water is among the world's best due to its intensive purification. However, increasingly precise analytical methods show that residues of chemical substances such as medicines are present in the drinking water. A report published in 2021 by the Dutch National Institute for Public Health and the Environment RIVM shows that substances that should not be present in drinking water in this quantity were found in more than 60% of the drinking water samples.

Demographic change, use of medicines and quality assurance for drinking water

The drought of the past years has led to an increased concentration of pollutants, but the demographic change in society and the accompanying increased use of medicines also play a role. The quality of drinking water in the Netherlands remains very good, but there is growing concern about future quality due to the factors mentioned above.

Advanced wastewater treatment: Houten gets first wastewater ozonation plant in the Netherlands

Advanced wastewater treatment is an important key to reducing pharmaceutical residues in surface waters. After a nationwide analysis, the wastewater treatment plant in Houten, a small Dutch town in the province of Utrecht with about 50,000 inhabitants, was determined to be an ideal location for the installation of the first water ozonation plant in the Netherlands. The most common techniques have shown that ozone is a suitable means of reducing the amount of pharmaceutical residues that enter surface waters via wastewater. It is planned to equip several wastewater treatment plants with this type of system in the future.

Ozone treatment in Houten takes place in a concrete ozone reactor equipped with aeration elements. These elements must be easy to inspect and easy to reach. A pressure-tight door is the best choice for safe and at the same time easy access.

Thus, HUBER’s pressure-tight door type TT7 was chosen for the ozonation plant in Houten. The doors are located seven metres under water and are equipped with sight glass, wipers and LED lighting for easy observation of the effect of the ozone. It is a customised product with adaptations made to the sealing and glass type to prevent corrosion by the ozone. The HUBER Pressure-Tight Door TT7 is an all stainless steel, ready-to-install tank access door specifically designed for drinking water supply. The rectangular HUBER pressure doors are pressure-resistant up to ten metres, open to the pressure side, are ready-to-install, can be covered on both sides (wall thickness ≥ 280 mm) and are statically tested.

The reactor consists of different chambers. In order to be able to carry out correct sampling from each chamber, pressure-tight HUBER Access Covers TT8a were installed on the ceiling of each chamber, which are resistant up to a gas pressure of 40 mbar. The HUBER access covers, specially developed for drinking water supply, are maintenance and inspection openings made of stainless steel, pressure-resistant up to 5 metres water column as standard. The round types are ready for installation, can be covered on both sides and include an interposed seal according to their field of application. A blind cover serves as a closure, to which two handles are attached for lifting, connected to the frame by screw connections.