High-load digestion Erbach – Scientific support during the technical realisation of the high-load digestion at SKA Erbach

Mayor Achim Gaus officially inaugurated the newly built high-load digestion unit on 20 May 2017 with an open day at the Erbach sewage treatment plant.

High-load digestion is a process developed by Fraunhofer IGB for the anaerobic digestion and stabilization of sewage sludge. This technology was implemented at the Erbach wastewater treatment plant.

The first step included preliminary investigations into the digestion of the raw sludge from the treatment plant under high-load conditions. For the following steps, a planning team was employed with scientific support from Fraunhofer IGB. This support ranged from the first appointment with the approval authorities, to assistance with the tender documents, accompaniment through the construction phase, cold commissioning and subsequent inoculation with digested sludge from a neighboring wastewater treatment plant, as well as performance testing. In mid-December 2016, this was followed by inspection and approval with the executing companies and final acceptance by the district office. Then the fully functional plant was handed over to the city of Erbach.

The percentage of sewage sludge to be disposed of was reduced by more than 25 percent. In this process, a large part of the organic material is converted to digester gas by anaerobic microorganisms. After purification steps, a combined heat and power plant utilizes the biogas produced to generate electricity and heat. These are then used at the wastewater treatment plant and in the adjoining municipal building yard.

The high-load digestion ensures that a large part of the energy required to operate the sewage treatment plant is supplied by the sludge digestion. Both electricity and heat are used effectively, achieving a favorably high level of overall efficiency. The next high-load digestion unit is already under construction.