Processing the biogenic fraction of residual solid waste into a co-substrate for biodigestion in digester towers at wastewater treatment plants

(Energetische Nutzung der biogenen Anteile im Restmüll als Co-Substrat in Faultürmen von Abwasserreinigungsanlagen, ENARA)



Supported by researchers of the Work Area Waste Treatment and Resource Management at the University Innsbruck, the project ENARA is realized by ATM GmbH. This project is part of STREFOWA, within the Interreg Programme Central Europe. It is co-financed by the European Regional Development Fund (ERDF). Additional funding comes from Tyrol’s government as well as from the Packaging Coordination Center (Verpackungs-Koordinierungsstelle, VKS)

Landtirol                          strefowa



Project Duration:

01.08.2017 - 31.03.2018


Project Partners:

  • ATM (Lead partner), IKB und AAG (coordination, preparation, and delivery of waste supply)
  • UIBK (biological-chemical analyses, scientific support)
  • MCI (development and implementation of hydrocyclone prototype)
  • Regional wastewater treatment plants (implementation of technological scale trials)



The aim of the project is to develop a treatment process by which the organic-rich fraction of residual solid waste (RSW) is transformed into a co-substrate for biogas production in digestion towers of wastewater treatment plants (WWTPs). The results of this project will be fundamental for the implementation of the process in industrial scale.


Project Description: 

Even after the introduction of separate biowastes collection, considerable amounts - between 20% and 40% - of biogenic wastes, like kitchen and food residues, are still found in RSW. According to EU legislation, these wastes must be submitted to thermal (waste incineration plant) or biological treatment (mechanical biological treatment plant) prior to landfilling.

Many WWTPs in Tyrol have been spaciously laid out and therefore possess considerable free capacities in their digester towers. In order to put these free capacities to good use, in some of these WWTPs, biowastes from separate collection are fed as co-substrates into the digestion towers for biological treatment, which results in increased biogas quantities and an improved energy balance of the WWTPs. The biological degradation process results in a sludge which has to be incinerated. Most of the nutrients contained in the biowastes are either destroyed or remain in the ashes, which are landfilled. Therefore, these valuable resources are lost for fertilizing purposes in agriculture.

If the biogenic components contained in RSW could be processed into a high-quality co-substrate for the digester towers in WWTPs, those biowastes originating from separate collection could be treated separately, and the contained nutrients could be recycled as fertilizer. Also, the energy balance of WWTPs with excess capacities in their digestion towers could be improved considerably.



  • Development of an optimal treatment combination for the separation of biogenic matter from the lower calorific fraction of MSW (partial waste stream from the mechanical treatment plant Ahrental, Tyrol);
  • Assessment of the effects the impurities possibly still present in the processed MSW could exert on the aggregates of the WWTP; determination of necessary adaptations;
  • Assessment of the biogenic waste potential contained in Tyrol’s RSW;
  • Investigation of biogas and energy potentials;
  • Assessment of the influence of the co-substrate on the degradation of wastewater sludges; back-contamination (especially by nitrogen) of wastewater lines by digestion effluents, quantity and quality of digestion sludge (dewaterability, impurities (heavy metals), phosphorus suitable for posterior reclamation, etc.);
  • Analysis and assessment of the technological and economic feasibility as well as of the environmental effects of the process, through Life Cycle Assessment methodology.


Contact Information:

Universität Innsbruck
Univ-Prof. Dr.-Ing. Anke Bockreis
Technikerstrasse 13
6020 Innsbruck

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