Replacing unreliable belt drive systems with gear motors and variable speed drives supplied by Bauer Gear Motor has improved control, reduced breakdowns and saved energy at a German municipal wastewater treatment plant


he residents of Ensdorf in Western Germany probably give little thought

to their local sewage treatment works. Many won’t even know where it is, since the facility has been designed to blend into the landscape. Yet Ensdorf sewage treatment plant plays a vital role in the social, economic and ecological fabric of the German municipality. Situated on the right bank of the River Saar, the sewage treatment plant processes the waste water generated by the region’s 50,000 or so inhabitants, together with effluent generated by several local industries. Like all modern sewage treatment

facilities, the Ensdorf plant relies on a combination of mechanical and biological processes to remove dissolved contaminants and solid materials from the incoming effluent. Its job is to ensure that water leaving the facility meets strict cleanliness rules, allowing it to be safely discharged into the Saar, and that the remaining solids are also transformed into a condition suitable for safe disposal, typically as agricultural soil enhancers. That’s a delicate balancing act. The

contaminants and solid wastes processed by the facility similarly vary over time. To keep the plant’s processes running properly, the plant’s staff must adjust the operating speeds of equipment across the facility as demand rises and falls. Originally, speed control in some of the

plant’s important equipment was achieved via mechanical means. As part of the sludge dewatering process, the pumps that supply sludge to the two centrifuges were powered by 7.5 kW asynchronous geared motors with belt drive adjustment. Additional pumps used a similar system with 4 kW motors to transport the thickened sludge away from the centrifuges and on to the next process. While the belt drive approach did enable the necessary speed control, the system proved unreliable in operation. Adjusting the belts frequently was inconvenient for operators, and breakages were common, leading to downtime and disruption. In search of a better approach, the

inflow rate to the plant can vary significantly, from 26,000m3 weather to 57,888m3

of heavy rain. The volumes of /day in dry /day during periods

The introduction of variable speed drives has enabled the automation of speed control


Promega has introduced Water-Glo, a tool to help analysts at water treatment plants, and in other industries where water quality is critical to a process, quickly and reliably detect living microbes present in a sample. Water-Glo offers plant operators, engineers and water quality specialists a sensitive and flexible measurement system for monitoring microbial contamination in, for example, freshwater, process water, seawater or waste water samples. Promega is established in adenosine triphosphate (ATP) detection – the ‘energy currency’ of all living

cells that degrades quickly when a cell dies. Its Water-Glo kits employing a lysis and detection reagent combination. Formatted for lab use in a 96-well plate format, Water-Glo kits and companion instrumentation can quickly analyse ATP levels in up to 90 samples in less than 90 minutes. ATP is emerging as a technology for gaining a better understanding of microbial populations in complex

water ecosystems. Users get a clear insight into how many live bacteria are in a sample and can predict how they might impact on water quality and process performance. In addition to public health concerns, bacterial growth causes issues such as biofilm formation (biofouling) and microbial-influenced corrosion (MIC) within pipelines and storage tanks. Early detection can prevent problems leading to contamination, downtime and costly repairs. Water-Glo gives an immediate indication of microbial contamination that conveniently shortcuts the

need to wait for microbes to grow in culture. This means that the effectiveness of biocide treatments or biological filtration processes can be monitored. Hemanth Shenoi, global commercialisation marketing

manager, Applied Markets, Promega, said: “Traditional testing methods require days for culturing bacteria and, often, by the time you find out there’s contamination, it’s already too late. Because Water-Glo is based on ATP bioluminescence technology, users get consistent, low-level detection of all live microbes in minutes rather than days, which makes it the ideal early warning system to protect critical processes.” Promega

plant’s managers contacted Klebs + Hartmann, a Bauer Gear Motor Gear Centre, who proposed a solution to resolve the reliability issues, and achieve energy savings. Matthias Klee, project engineer Drive Technology, and Peter Siepel, project engineer Inverter Solutions, worked together to create a bespoke solution. That solution was based on the introduction of variable speed drive (VSD) controls and high-efficiency permanent magnet gear motors supplied by Bauer Gear Motor, part of the Altra Industrial Motion Corporation. The new approach solved Ensdorf’s

reliability challenges at a stroke. The introduction of variable speed drives eliminated the need for belts and allowed the automation of speed control in the transport systems for the centrifuges. In addition, the Bauer motors selected for the project are IP66 rated, providing increased protection against corrosion and the risk of water damage from cleaning. The greater efficiency of the modern

motors enabled significant energy savings. In fact, the new IE3 motors are so much more efficient than the older, unrated units they replaced that downsizing was possible. The pumps that supply the centrifuges are now powered by 6.3kW units rather than 7.5kW and the downstream pumps are powered by 3kW motors instead of 4kW. After successful testing with one of the centrifuges, Ensdorf has now installed the new Bauer motors in all four locations, making life easier for operatives at the plant.

Bauer Gear Motor

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