Sanitary products, wet wipes, cleaning rags: the persistently high proportion of solids in sewage regularly brings waste water pumps to a standstill. The Treis Sewage Treatment Plant of the Cochem Collective Municipality, the largest SBR (sequencing batch reactor) system of its kind in Rhineland-Palatinate, has like others been battling for years with this problem. Previously, pumps at a connected pump station would break down at least once a week due to blockage and need to be cleared laboriously by hand. In 2019, therefore, the operator decided to gradually replace the fault-prone and high maintenance models with new EffTec pumps using MXS hydraulics from HOMA Pumpenfabrik GmbH. The flow-optimised hydraulic system effectively prevents blockages and clogging. For that reason, this pump series is particularly suited to applications involving high levels of solids, as is the case in Treis-Karden. By 2021, a total of three EffTec pumps had been installed there. Thanks to their high degree of adaptability, the refit all went smoothly. The new pumps have reduced maintenance interventions at the pump station by 95 %.

EffTec Pumps Master High Solid Content in Wastewater

“Our old pumps had been in use since 2004. At the start they were becoming blocked up to five times a week and even after various expensive adaptations, they were still doing so weekly,” reports Karl Neiss, Waste Water Manager at the Treis Sewage Treatment Plant of the Cochem Municipal Waste Water Works. The frequent breakdowns on the old pumps, which occurred disproportionately often on Sunday nights or public holidays such as Christmas Eve, kept staff at the Treis Sewage Treatment Plant permanently busy. Aside from the journey to the pump station involved, the affected unit had to be painstakingly dismantled by hand and the material that it was clogging it – cleaning rags, sanitary products and sometimes even old clothes – removed. All of these steps could take up to 75 minutes per blocked pump, in some cases several times a week. “It was therefore a happy coincidence when we got to know the staff from HOMA Pumpenfabrik at IFAT in 2018, and as a consequence heard about the EffTec pump series,” continues Neiss.

After carrying out an assessment of the problem at the relevant pump station in Treis, HOMA recommended installing EffTec pumps, which are specifically designed for use in situations affected by high levels of solids. Common problems causing the blockage of waste water pumps at the site include a low flow rate inside the pump and large gaps behind the impellers and in the intake area between the impeller and the pump chamber. “The EffTec pumps therefore have improved hydraulics with enclosed single-channel impellers and optimised ball passages, allowing high rates of flow,” explains Florian Steiner, sales representative at HOMA Pumpenfabrik. “The flow-optimized impellers generate no turbulence, so solids are able to pass through the hydraulics without difficulty.”

Robust Pumps Guarantee Reliable Operation of the Pumping Station

At the pump station in Treis, a vertical dry installation of one EffTec unit was carried out each year in 2019, 2020 and 2021. “With the first installation we had to make a few adjustments because the new pump was not compatible with the existing pipework,” Steiner reports. In principle, though, we ensure a high level of adaptability with our units, so that the required conversion was unproblematic.” For the operators of the sewage treatment plant, the investment soon paid off: once the first EffTec pump was installed at the end of May 2019, it ran without any blockages for over a year until the first maintenance work was required in June 2020. “Since then, maintenance has been required only once a quarter,” concludes Neiss. “Compared to the weekly problems with the old units, that means a 95 % reduction in maintenance costs for us.”

In addition to the safe and low maintenance running of the EffTec units, the operators of the pump station in Treis also benefit from their tough combinations of materials. So far, no repairs of any kind have been required and none of the impellers has had to be replaced, even though these are usually particularly susceptible to damage. “Through their optimised hydraulics, we have managed to make the EffTec series very smooth running, minimising the stress on the individual components,” explains Steiner. Furthermore, the pumps are fitted with the PermaCool system which allows for wet or dry installation. With this patented design, the motor is continuously cooled but the cooling jacket cannot get clogged with solids.

Karl Neiss and his colleagues feel altogether well advised by HOMA and pleased with their collaboration over the long term too. Due to their positive experience, the operators are already planning to replace further old and fault-prone pumps with new units from the same manufacturer. “Just as the inhabitants of Treis-Karden can depend on the round-the-clock reliability of the sewage treatment plant, we also must be able to depend on the reliability of our pumps,” concludes Neiss. “Nowadays the only reason to go to the pump station is to clear away the cobwebs.”