Reference flow in the MFA for which is suitable the technology

Short Description

Incoming MSW is pretreated mechanically (shredding, sieving, removal of metals) and split into three fractions: a high, a medium, and a low calorific fraction, with a grain size < 40 mm. The high and medium fractions are used for RDF, while the organic fraction (OF) of the low calorific fraction will be fed into the digesters of WWTPs for enhanced biogas production.

The managerial solution consists in administrating the newly generated organic fraction and the newly generated waste streams: calculation of general mass potential, distribution of required quantities to the WWTPs, optimizing transport logistics, managing biogas production, managing the predominantly mineral residues and their further processing (p.ex. separation and sale of recyclable glass cullet) and their final disposal.

Organizative processes to support closing the loops

Inside processes: The mechanical waste treatment plant (MWTP) receives MSW as well as bulky wastes, usually with little or no organic fraction (OF). Therefore, the management of the MWTP has to make sure that only that part of the LCF which resulted from MSW treatment is going to be further processed for the separation of the OF. Thus, a quality control protocol needs to be in place. In Tyrol’s case, the OF of the LCF, when fed into the digesters of WWTPs for biogas production, will replace the organic wastes from source separate collection commonly used for this purpose. These organic wastes usually have a very low concentration of contaminants and therefore are more suitable for fertilizing purposes, thus contributing to closing the loops of certain minerals, p. ex. phosphorus, a critical resource. However, in a near future, the sludges of WWTPs will be legally banned from being used as fertilizers, and therefore the fertilizer potential of the clean organic wastes from source separate collection will be most probably lost, because viable industrial processes for their recovery are still expensive and not yet wide-spread. The proposed CE-solution therefore replaces the outside process of clean biowaste digestion at WWTPs, which then can be treated in mono biowaste treatment facilities. By doing so, the CE solution enhances the local and regional biowaste treatment sector and contributes indirectly to local and regional recycling of important plant nutrients and carbon.

Practitioners opinion

Not yet available 

Possible limiting factors

• Costs: Reliable data on costs and revenue not yet available.
• Degree of implementation at local scale: Project is scheduled to be implemented at local scale (date unknown)
• Other stakeholders involved: MWTP, WWTP, waste transport firms, local landfill. 

PP’s opinion of the technology

Although the technology of the proposed CE-solution is promising, its success depends on the acceptance by the WWTPs’ operators, and their cooperation. The results achieved with the technology until now are restricted to the physical composition of the potential co-substrate from MSW-LCF, which indeed has a very low impurity content. However, no reliable data on its biogas potential exist to date, especially from a continuous biodigestion process. This is currently carried out by a third party, and the results will be made available to the PP.

Concept and conclusions how the technology can affect the CE effect

1. Existing technology in the MWTP is applied to produce the input material: LCF < 12 mm
2. A newly developed hydrocyclone, based on existing technology but adapted to the specific technical requirements of the input material, will be used to produce an organic, liquid fraction, with a very low content of impurities, with a sufficiently high biogas potential to make it suitable for co-digestion in WWTP reactors.
3. The (partial) substitution of source separated organic waste, until now used as co-substrate in WWTPs, is one of the expected outcomes. These organic wastes would then be available for biodigestion and composting in a mono bio-waste treatment facility, and subsequent land application for fertilizing, closing local nutrients and carbon loops.
4. Another expected outcome is the increased regional overall biogas production potential, when the OF of the LCF is used as an additional co-substrate in WWTPs
5. The implementation of the CE-solution is realistic. Stakeholders are organized in a mutual effort to make waste and wastewater management and the respective treatment facilities more sustainable, thus contributing to the further development of a regional circular economy. This is supported by EU and country-specific legislation, including financial support for the development of respective R&D.

Charts, photo, diagrams

References

Meirer, M., Müller, W. & Bockreis, A. Österr Wasser- und Abfallw (2017) 69: 397. https://doi.org/10.1007/s00506-017-0411-2.

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