Project meeting of STEP at the site of the company ATS - Agro Trading & Solutions in Hardegsen (Photo: DBFZ)

sector coupling | CHP Heat Power Validation market potential Biomass furnace System integration

Project ID 03EI5428

VerKlär² - Utilization concept for energy self-sufficient and resource-saving wastewater treatment plants: Integrated sewage sludge and sewer gas utilization


  • 01.03.2021 – 31.08.2024


City Hassfurt
Hauptstraße 5
97437 Haßfurt

Günther Werner – project leader
Telephone: +49-(0)9521 668-0

Tina Heller – direct contact person / project coordinator
Telephone: +49-(0)9521 668-127

Matthias Langguth
Telephone: +49-(0)9521 3372


03EI5428B - RWTH Aachen University
03EI5428C - Institut for energy management IfE GmbH
03EI5428D - Spanner Re² (Renewable Energy Experts) GmbH

Associated partners

Cooperation partners



planned results:

  • plant level: pilot plant, demonstration plant
  • concept level: plant concept
  • publications: scientific papers (ISI, peer-reviewed)
  • market level: marketable technologies


The objecitve of the project is the demonstration of environmentally friendly, energetic sewage sludge utilisation in an innovative fluidization furnace for wastewater treatment plants in the classification size 4a with 10,000-50,000 population equivalents using the example of Hassfurt. Recent amendments to the Sewage Sludge Ordinance have resulted in an increased demand for mono-incineration capacities. As a decentralised process for sewage sludge incineration, the new technology can provide an important ecological contribution. The broad fuel band of the patented technology makes the energy supply more flexible by using additional biogenic residues in order to compensate fluctuations in fuel supply and prevent disrupting effects on the local energy system. Process-related advantages are offered by the optimization of emissions due to the establishment of different incineration zones for primary reduction of nitrogen oxide emissions. Planned investigations on the direct injection of additives should enable a reduction of pollutants in the ashes directly within the furnace and thus the production of a suitable educt for future phosphorus recycling. The technology has already been tested with sewage sludge in a prototype but has not yet been transferred into field operation.


Objectives of the project include the conception, implementation, commissioning, technical optimisation and long-term demonstration of the furnace as a modular incineration unit for sewage sludge. The results are used to establish this decentralised treatment process for sewage sludge and other biogenic residues, with complete coupling of the process heat into the infrastructure of the wastewater treatment plant, for sludge drying and heating of buildings. The goal is to achieve a selfsufficient energy supply for wastewater treatment plants by intelligent and flexible combination of sewage sludge incineration with the generation of electricity from sewer gas.


City Haßfurt

  • Sampling and characterisation of the sewage sludge
  • Integration of the furnace into existing wastewater treatment plant infrastructure
  • Plant installation, commissioning and transfer to continuous operation

RWTH Aachen University

  • Characterisation and analysis of sewage sludge
  • Investigation of thermal behaviour on a laboratory and pilot plant scale
  • Preliminary tests and process optimisation in an existing prototype
  • Re-engineering of the incineration plant
  • Construction and operation of the pilot plant

Institut for energy management IfE GmbH

  • Integration of the firing system into existing wastewater treatment plant infrastructure
  • Construction and commissioning of the pilot plant
  • Economic and ecological process evaluation

Spanner Re² GmbH

  • Re-engineering of the incineration plant
  • Manufacture of the pilot plant
  • Installation and commissioning of the pilot plant


City Haßfurt

IIntegration of decentralised sewage sludge incineration in a fluidization furnace for solid fuels into the local wastewater treatment plant operation

RWTH Aachen University

Applied investigation of decentralised sewage sludge incineration in a fluidization furnace for solid fuels

Institut for energy management IfE GmbH

Integration of the furnace into the existing wastewater treatment plant, scientific-measuring and economic evaluation of the project

Spanner Re² GmbH

Manufacturing and optimisation of a pilot plant for decentralised sewage sludge incineration


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