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Why does modern aeration technology make the treasurer happy?
The aerzen combined system provides optimum efficiencies at the wallau wastewater treatment plant
The combination of different technologies for air conveying enablesoptimal energy use of oxygen for biological degradation processes in wastewater treatment plants. Concrete savings resulting from the use of AERZEN machines demonstrate this in practice at the Wallau plant.
In 2016, the independent central Hessian wastewater association “Perfgebiet-Bad Laasphe” modernised its wastewater treatment plant on its own, with only the support of “UD Umwelt-DiensteGmbH”. “If we had gone the way of a tender, a less expensive solution would probably have been selected, but not necessarily the best one,” explains Production Manager, Gernot Wege. His team on site knows everything about the plant, particularly where oxygen demand in the aeration tanks is concerned. So, the wastewater association started searching for a solution with this data in hand. Today, a blower combined system, consisting of Turbo and Delta Hybrid, with connected Aerostrip fine-bubble diffusers made by Aquaconsult, guarantees perfect oxygen entry in the aeration tanks. 39,000 inhabitants on both sides of the River Lahn are connected to this wastewater treatment plant. It was easy to install the new and modern fine-bubble diffusers directly onto the base of the tanks. The mounting layouts did not have any negative influence on the water level, which remained stable. Thanks to this system change, the surface aerators which had hitherto been used, became a thing oft he past. Two concrete bridges mounted to the rotor units above the aeration tanks were also no longer needed. “We were ableto use the newly available space to mount the new blowers,” explains Rüdiger Vrabac, Division Manager, UD GmbH in Friedberg.
The now-available space used anew
Each bridge now has a small structure which protects the combined blower system from wind and weather. Furthermore, the housing provides noise protection. The decentralised setup directly above the aeration tanks also has another advantage for Vrabac: “We saved not only on construction costs, but alsoonlong and expensive stainless steel supply pipes.” The tandem mode is mainly designed for considerably differing load requirements during winter and summer time. For higher air requirements during the summer months, the wastewater association uses the AERZEN turbo blower as an efficient base load machine. For this purpose, the type AT 100-0.6 S supplies a volume flow up to 4,200 m³/h. In winter, the system can switch to Delta Hybrid, as less oxygen is necessary for aeration at this time of year. The maximum volume flow of type D 36 Sis 2,150 m³/h. The major difference evidentat Wallau is the result of its special geology, as the sewer system carries a comparatively high level of groundwater, which strongly dilutes the waste water. Due to a schist layer, the rain cannot be directly drained. Eventually, however, the energy savings of 15% forecast at the beginning of the project in Wallau were considerably exceeded. The new combined system has already achieved savings of 26% in respect of the electricity demand of the entire wastewater treatment plant. In view of the fact that the aeration needs only half of the previous electricity demand, the retrofitting in this sector yields savings of more than 50%.