Electricity and Control January 2023


In another project in the Netherlands, Dutch Spiral, a company based in Groot-Ammers, offers an optimal solution to dealing with and disposing of the residual materials from wastewater treatment plants safely, cleanly and with minimal odour – using a container system and an integrated screw conveyor. Compact radar sensors fromVEGA are used to monitor the levels inside the containers to ensure they are exchanged in good time. Radar sensors ensure a clean solution

I n wastewater treatment, the main focus is of course on the end product – clean water. But many individual pro cess steps are involved along the way. These produce various residual materials that have to be disposed of safe ly and efficiently. For example, the screenings, the sludge and the sand – how do you dispose of them? The core product of the Dutch family-owned business Dutch Spiral is the shaftless screw conveyor. Dutch Spiral, together with the company Huber, also offers an ingenious solution for handling the residuals of wastewater treatment. This solution is used in almost every wastewater treatment plant in the Netherlands. It is basically a container that is filled automatically via an integrated screw conveyor. More than 230 such containers are currently in use in the Netherlands. Although there are other prefabricated, compact solutions on the market, these containers have the advantage that they can be adapted to the situation on any site. Automatic filling Screenings, sand and sludge are further processed in the containers. The STC dewatering container was specially developed to transport dewatered sludge without contami nating the environment with unpleasant odours. Depending on the design size, the container can hold up to 30 cubic metres of sludge. The Dutch Spiral Screening Container RGC, on the other hand, was specially designed to trans port the screenings. A key advantage of both systems is that the filling process is completely automatic; the level of filling and frequency of transport, however, can be controlled remotely. The container is positioned and secured using placing ramps. It is filled via a chute or a screw conveyor. At the end and at the inlet of the container there is a gas spring operated shut-off valve. The shut-off valve is equipped with a proximity switch that detects the position of the container and the open position of the slide. Below the collapse sleeve is Dutch Spiral’s shaftless screw conveyor, which, in turn, is driven by a bevel gear. Reliable stop The filling level inside the container is monitored with the help of level measurement. And this is where sensors from VEGA come into play, delivering a reliable signal when the

Sludge, sand, wood – the residual materials from wastewater treatment plants demand a lot from the deployed sensors.

The new series of compact radar level sensors measures the level in the containers, without contact.

JANUARY 2023 Electricity + Control


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