Energy recovery from the low calorific fraction (LCF) of a mechanical waste treatment plant



Reference flow in the MFA for which is suitable the technology

Low calorific output of a mechanical waste treatment plant

Incoming input

The LCF is one of three  output flows of the local mechanical waste processing and recycling plant. The material is composed of the residues left after the following processes: shredding, sieving at mesh sizes of 80 mm and 40 mm, and separation of recyclable metals. The material is humid and rich in organic matter. 

Outgoing output

The material stream (LCF), after the CE solution process, results in two output flows:

  • Solid LCF (40 – 12 mm grain size) containing the inert fraction (glass, stones, sand and other impurities < 12 mm grain size),
  • Liquid, organic fraction.

Technology description

The proposed technology represents of a form of hydro-mechanical treatment.  It consists of a specifically designed hydrocyclone, which separates a prepared LCF/water pulp into a solid and a liquid phase: the solid phase containing the impurities, the liquid phase containing the biogenic, biodegradable compounds, then sent to anaerobic digestion. 

Organizative processes to support closing the loops

For logistic reasons, the hydro-mechanical pre-treatment and the anaerobic digestion will be located at a wastewater treatment plant (WWTP). Therefore, the incoming material will have to be transported from its place of origin (mechanical treatment plant) to the WWTP, and the relevant logistics need to be organized.

 The wet pre-treatment unit will have to be operated and maintained at the WWTP and staff needs to be organized.

Practitioners opinion

Relevant and benefiting practitioners are predominantly operators of WWTPs.

Plant operators are generally open to further develop their plants and to take up new tasks associated with this innovation process. In particular, they are positive about advancing the co-fermentation process using additional new substrates if necessary.

The main concerns about the use of the potential co-substrates produced from LCF are about possible concentrations of impurities.

Possible limiting factors

The costs are the major limiting factor. This includes investment, operation and maintenance. A detailed life cycle cost analysis and a business plan are necessary to plan expenses and potential revenues.

PP’s opinion of the technology

The project partner has looked into this technology in detail and compared it with the existing solution. This technology was found to be competitive regarding costs and performance. 

Concept and conclusions how the technology can affect the CE effect

Test runs with the prototype of the technologyto analyse its performance regarding composition of the output material have been conducted successfully. 

Is the technology a BAT?


Charts, photo, diagrams


Meirer, M., Müller, W. & Bockreis, A. Österr Wasser- und Abfallw (2017) 69: 397.

Leonhartsberger, C., Müller, M., Meirer, M., do Carmo Precci Lopes, A. (2018): Endbericht. Machbarkeitsstudie ENARA. Interner Bericht.

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