The wastewater disposal association “Obere Amper” (AZV) is having its sewage treatment plant at the Amperschlucht in Grafrath converted to new technology for climate protection reasons. The costs for the so-called anaerobic sludge stabilization, the conversion of which is expected to take until the end of 2025, are calculated at around six million euros. However, the cost estimate is from 2021, so additional costs cannot be ruled out due to inflation, for example in wages and materials. In the anaerobic process, the sewage sludge is stored in the absence of air and is thereby stabilized so that no odors arise and germs that are harmful to health are broken down.
According to a resolution by the AZV Council, the households in Grafrath, Kottgeisering and Türkenfeld, which can use the sewage treatment plant through a special purpose agreement, will not receive any special payments. The waste disposal company would like to refrain from making “improvement contributions”. As the AZV chairman, Kottgeisering's mayor Andreas Folger (BV), informs, the conversion will make “an important contribution to a climate-neutral world”, as after the conversion the energy requirements for the sewage treatment plant can be covered from renewable energy. This is obtained from the anaerobic stabilization of the sewage sludge and by means of co-digestion (with the addition of suitable organic waste) in a digestion tower. Similar to a biogas plant, the sewage sludge with added substrate ferments (rotts). The resulting sewage gas is used to produce electricity and heat in a combined heat and power plant and use it straight away. “One of the positive effects is that harmful methane gas is no longer emitted into the atmosphere during operation of the sewage treatment plant. In addition, the anaerobic sludge stabilization significantly reduces sewage sludge transport and thus CO₂ emissions,” explains Folger.
The conversion is a major financial challenge for the AZV, even though the project is subsidized by the Free State of Bavaria and the Federal Ministry for Economic Affairs and Climate Protection with a total of around one million euros. According to Folger, the federal funding comes from the non-profit project management organization Zukunft-Umwelt-Gesellschaft ZUG gGmbH. As a project sponsor, ZUG develops, supports and promotes important projects relating to the protection of the environment, nature and climate as part of the national climate protection initiative. The Free State of Bavaria's funding is based on the “Municipal Climate Protection” guidelines, which are intended to help make Bavaria a climate-neutral federal state by 2040 at the latest.
The municipality of Türkenfeld must also make a financial contribution as a guest user. “Without this state funding and the contribution of the neighboring municipality, we would not be able to shoulder the conversion,” reveals the AZV boss and explains that the remaining costs can essentially be covered by reserves and loans as well as ongoing fees. According to Folger, construction work has already begun. “Machine technology”, the most expensive area, will be awarded shortly so that we can start as planned.