Pumping solids without screening
Climatic changes force us to save water. Given that the pollution load has remained the same, the solids content in wastewater has increased, which has been a technical challenge for wastewater treatment plants. Until now, upstream pumping stations have had to implement costly measures to ensure reliable operation. KSB has responded to this problem with a new technical development that eliminates a previously essential step in pumping stations.
Many years of close partnerships with customers have provided KSB with detailed insights into the problems and challenges its products face in daily work. This has enabled KSB to tune its technical solutions precisely to what customers need. KSB’s sales engineers recognised that cutting back on processes in wastewater pumping stations would save considerable costs. In the end, they just had to convince their customers of this solution.
The city council of Oelde, located in the southeast Münsterland region in Germany, operates a public sewer system of about 280km in length for its 30,000 inhabitants. Nineteen pumping stations make the wastewater flow from suburbs such as Stromberg, Sünninghausen and Lette to the wastewater treatment plant, where 8,500 cubic metres are treated mechanically and biologically every day.
In addition to pump technology, wastewater pumping stations are fitted with components such as screens and strainers that mechanically pre-clean the wastewater upstream of the pumps. This prevents clogging or damage to the pumps. Wet wipes from hygienic applications, in particular, make wastewater transport difficult. Having to remove solids and service the screens incurs extra costs.
KSB has further developed its Amarex KRT and Sewatec pump type series. A new impeller has been designed that can handle wastewater with a high solids content without clogging the pump. This means the pumping station operator can do away with any upstream components for mechanical pre-screening—a distinct advantage.
Once several prototypes were available, KSB started a field test where the pumps had to prove their worth in practice. Oelde’s Obstromberg pumping station was the first to use one of the newly developed pumps for a free trial operation. KSB supplied a Sewatec D-max and had it installed by engineers from the KSB service network. Installation was straightforward as the technically advanced pump was designed with standard dimensions. Only the hydraulic part of the pump has changed, and a larger suction pipe has been fitted.
In the one-month trial operation, Sewatec D-max 100-403 was used with the previously fitted upstream screen. After running successfully for this period, the pump was then operated without the screen. And it worked: Even without mechanical pre-screening, the pump was able to handle coarse solids together with the wastewater without clogging. Twelve months after the trial operation had started, the Oberstromberg pumping station ordered a second Sewatec D-max. This additional pump has provided trouble-free operation together with the first pump since mid-2022.
The upstream screen, initially planned to be renewed, has since been completely removed from the pumping station, saving the operator a six-digit investment. A useful new technical development has eliminated a process that had been established for decades, including the associated costs for disposal and servicing.
