Edition 03/15

The project SEMIZENTRAL, of the Technical University Darmstadt in the Chinese coastal metropolis of Qingdao, has been given a GreenTec Award. This project shows how to plan infrastructure as needed, and how to put these infrastructure plans into practice. Instead of building one central sewage plant for the entire city, the scientists have pursued a semi-centralised approach with a number of smaller plants. This enables cities to grow in sections and consequently, the water supply and water disposal infrastructure can do likewise. Within this scope of application, AERZEN blower technology has been among the established equipment used worldwide for more than 150 years.

Efficient engineering made by AERZEN

For optimal water treatment, the Technical University Darmstadt and its cooperacooperation partners, Tongji University Shanghai and Qingdao Technological University, applied an especially energy-efficient technology. With regard to sewage water cleaning, basin aeration uses the highest amount of energy, so the application of energy-saving solutions is well worth the effort. For this reason, the decision was made in favour of the AERZEN series Delta Blower and Delta Hybrid. “We were looking for economical blower packages which transport air by means of high volume flows”, recalls Dr. Susanne Bieker, Research Project Manager.

Air quantities to be controlled as required

In the aeration basins, two Delta Blower packaged units ensure that in grey water treatment systems, the microorganisms do not run out of air. The blower GM3S supplies a volume flow of up to 210 m³/h. To ensure that the semi-centralised plant, which was taken into operation in 2014, is always working within an optimal range, both functionally and in terms of energy use, components are required which also work with high efficiency in partial-load operation. The adjustment of motor speed and flow capacity to suit daily demand is done by frequency converters. Under similar conditions,AERZEN Delta Blowers can be applied in membrane filtration basins as well. The generated air flow works as an air blade which removes the biofilm from the diaphragm and prevents the fine pores from clogging. For this, both air quantity and pressure are the decisive factors, and are reason enough to use, in this case, the efficient positive displacement blower GM 10 S made by AERZEN, which delivers a volume of up to 542 m³/h at a differential pressure of up to 1 bar.

The best of both worlds

For the treatment of black water, three Delta Hybrid packaged units are in operation, with a capacity of 690 m³/h. With this series, AERZEN has succeeded in combining the operating principles of the positive displacement blower and the screw compressor in such a way that they are comparable with standard compressors, but these units require 15% less current. These world first rotary lobe compressors offer completely new possibilities for the generation of negative pressure and overpressure by ingeniously combining the technical advantages of both concepts. For the Technical University Darmstadt these aspects influence the selection of suppliers as Dr. Bieker explains: “We use technology which is highly efficient in terms of energy use and reliable over long periods of time. Everything needs to be coordinated properly.” Worldwide service and a quick supply of spare parts are mandatory as well.

Further optimisations for the future

Productivity, reliability and energy efficiency are becoming ever more important considerations in European mechanical engineering in the assessment of process technology. Dr. Bieker reports that the total cost of ownership (TCO) hardly plays a role in China anymore. In view of increasing urbanisation, the efficient use of water is becoming more and more important. Saving is well worthwhile! Therefore, AERZEN steadily continues its research in terms of maximum energy efficiency and economy for blower technology.