About the Nereda® WWTP Vroomshoop
The town of Vroomshoop is located in the province of Overijssel, in the north east of the Netherlands.
The conventional wastewater treatment plant (WWTP) at Vroomshoop serves a population equivalent of 12,000 and was built in 1972, since when it had not been modernised. Water authority Waterschap Vechtstromen (WSVS) identified a need to expand and renew the outmoded sewage water treatment plant, to meet current standards in the removal of phosphorous and sedimentation.
Image: The typical hybrid system: on the right the Nereda technology, on the left hand the traditional
Water authority Vechtstromen selected Nereda technology as the solution to the plant’s requirements. As the process of aeration and settling out occurs in a single tank, this saves on both energy and space. However, Vroomshoop is an exceptional case. The water authority chose to modify the Nereda design, as it was clear that a great deal of rainwater runs to the plant compared to the normal amount of wastewater. In addition to the Nereda technology, the scheme also combines conventional activated sludge technology into the process. The two tanks sit adjacent to each other and work in combination, to treat the effluent. The two systems work in parallel to purify water biologically, with sieves graded to remove particles over 1mm and 1.4mm. The added value of two technologies – new and old – in tandem, should lead to extraordinary results to cope with increased flow rates.
The bacteria in the Nereda technology forms granules instead of flocs, which settle out quicker. In Vroomshoop the traditional system treats 50% of the wastewater, Nereda the other 50%. By bringing the granular sludge from the Nereda reactor to the conventional system, the sludge settles better, making the purification process even more compact and efficient. In the Nereda reactor, both purification and sedimentation occur within the single space, but in the conventional system, the purification and sedimentation occur separately in settling basins. Using the two systems together brings out the best in both technologies and demonstrates how old technology can sometimes show the way forward towards new innovations. The daily average flow rate of the Nereda installation is 2,808 m³/day, with peak flow reaching 1265 m³/hour. The system started up in 2013 and has shown successful results since. Experts are now studying the advantages inherent in using this combination of treatments and are looking at the ways it may impact on other projects in the Netherlands and worldwide.