The pumping of municipal raw sewage is a great challenge. The main problem here is the percentage of fibrous materials, which in the form of wet wipes or similar, is found in the municipal raw sewage in an ever increasing quantities.
For years now, we have been offering our patented Turo® TA free-flow pump impeller, which was developed specifically for pumping wastewater. The new pump EOA series was developed to achieve higher flow rates compared to the fully recessed vortex pumps. It is based on a 2-bladed, half-open radial impeller.
Currently, various pumping stations and sewage treatment plants in Switzerland and Germany are equipped with these pumps. A clog-resistant pump alone is no longer sufficient to meet today’s requirements, it must have a correspondingly high energy efficiency. To continue and improve this development is our motivation. At the beginning of 2020, we installed an entirely new EOA impeller size EOA 8-250 for practical testing.
The impeller was previously tested at the Technical University (TU) Berlin on a test stand with a standardized wastewater.
Already first measurements after the installation on the sewage plant showed that the very good values of the measurements from the TU-Berlin were confirmed in practice. Efficiency improvements of up to 10 percentage points with raw sewage compared to the original version could be proven.
A good indication is the effective energy requirement to pump 1 m3 of raw wastewater 1 m high [kWh/m3 * m]. This value includes all power losses of pump, motor and frequency converter. The theoretical value (individual efficiency 100%) is 2,725 Wh/m3*m. The optimum achievable in practice with raw sewage is 4 Wh/m3*m.
A proven examination of the anti-clog properties of a pump is the one-hour run-test. Here the pump is operated at constant speed and the flow rate is measured. The flow rate must remain constant over time. This shows that the incoming fibres are conveyed at 100 %. Thus, the pump is entirely free of any clogging!
The resistance to clogging was significantly improved. This can also be judged by the required torque of the pump. In the same period, there was 4.7 times less torque related pump shutdown than with the first impeller generation. Under the same conditions of use of a single-channel wastewater pump with spiral impeller the value was even 5.8.
In summary, with the development of the new EOA impeller, we have achieved an energy-efficient and clog-resistant pump that is close to the optimum. We are thus prepared for future requirements by a planned eco-design directive for wastewater pumps of the EU.
You can find further information on our website: Wastewater Pumps EOA