Within the Interreg ANCHOR project, four demo sites across the North Sea Region are examining how vacuum-based wastewater systems function in daily operation. One of these demo sites is De Nieuwe Dokken in Belgium, where DuCoop manages a vacuum sewer system that transports toilet wastewater using air instead of large volumes of water. This approach significantly reduces drinking water consumption and supports more resource-efficient sanitation. This article explains why scaling occurs inside vacuum pipes, how it can be prevented or removed, and why high-pressure water cleaning is an effective and important method.
Why scaling forms inside vacuum sewer pipes
In a vacuum sewer system, wastewater is transported rapidly using air. When the transport is not efficient enough or when small air leaks occur, liquid can dry out on the pipe walls. Over time, the remaining material crystallizes and becomes increasingly hard. In some cases, the scaling can become cement-like. As the layer thickens, the internal diameter of the pipe decreases, which increases friction and flow resistance. This raises the risk of blockages and puts unnecessary strain on the vacuum system.
To limit scaling, regular chemical dosing can be used. Chemical treatment helps reduce initial build-up, but once scaling has formed, experience shows that mechanical cleaning methods are usually required for effective removal.
Mechanical and chemical cleaning methods
One option for removing hardened scaling is mechanical scraping. Tools such as scraping chains can physically break off the material, but the method is aggressive and may damage the pipe material if used repeatedly or with excessive force. Chemical dosing, on the other hand, is gentler and helps slow down new scaling formation, but it is not always sufficient for removing thick or hardened deposits.
For this reason, most systems rely on a combination of preventive chemical treatment and a more powerful cleaning method when needed.
Why high-pressure water cleaning is an effective alternative
High-pressure water cleaning offers an efficient and less invasive way to remove scaling without damaging the pipes. During cleaning, a hose is inserted through an access point and a specially designed nozzle sprays water at high pressure. This breaks down and washes away the scaling, restoring the internal pipe diameter. The level of cleaning achieved depends on two main factors: the type of nozzle and the pressure used. Different nozzles are suitable for different pipe materials and scaling thicknesses, which makes choosing the right tool an important part of the process.
The water and loosened residues are then removed. This can be done either by keeping the vacuum system active during cleaning or by connecting a vacuum truck downstream to extract wastewater and debris.
Supporting reliable system operation
Regular high-pressure water cleaning helps prevent struvite formation, reduces the risk of blockages and ensures that the vacuum system continues to function reliably. For users, this means fewer operational disturbances and stable toilet performance. For the Interreg ANCHOR project, the experiences from the De Nieuwe Dokken demo site offer valuable insight into how scaling develops in vacuum systems and how different cleaning techniques can complement each other. By comparing results from the four demo sites, the project aims to strengthen shared knowledge on maintenance strategies and support long-term development of robust, resource-efficient sanitation solutions in the North Sea Region.
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