**6. Conclusions and Recommendation**

The ERWP model presented here serves for the planning of a waste managemen<sup>t</sup> system based on the all known forms of recycling, including recycling of energy. The disposal of municipal waste based on the presented model is, in fact, an implementation of the circular economy strategy, in which waste becomes a raw material. The model, taking into account specific features of the given waste, provides for proper preparation of the raw material constituting a charge to the energy generating process. This pertains mainly to separation, through mechanical separation of mixed waste, of highly energetic RDF having an HHV value close to 24.5 MJ/kg versus 16 MJ/kg of mixed waste directed to combustion in its entirety. The separated organic fraction together with dehydrated sewage sludge is then subjected to methane co-fermentation in low water content conditions featuring a high unit gas yield of 265 dm3/kg *dm*. The remaining part of the sewage sludge is directed to the wet fermentation process. The application of three energy-generating processes in the model described above provides a source of alternative energy, reducing consumption of fossil fuels such as crude oil, natural gas and coal. In a year, the energetic value of generated biogas and raw materials originating from selective collection as well as separated from the mixed waste stream for a municipality, with a population of almost 106,000, is 79,917.6 MWh, which substitutes approximately 10,000 t of coal.

The described ERWP model can be used in planning and implementation of an effective waste managemen<sup>t</sup> system of any scale. The effectiveness of the model has been demonstrated on the grounds of a medium-sized city having approximately 110,000 inhabitants. As a rule, bigger cities generate larger volumes of waste, which increases the profitability of the implementation of a system based on the ERWP model. The fundamental advantage of the model is the use of practical processes that make up the system, where products from one site become a raw material for other sites. Thus, potential stakeholders generating or gathering municipal waste are united by one goal—effective waste processing. The unit value of energy generated in the system based on the ERWP model amounting to 754 kWh/inhabitant/a cannot cover all of the energetic demand of the local population. However, the example of Copenhagen shows that the share of energy generated from municipal waste processing may constitute up to 40% of the entire energy demand. Use of the alternative source of energy, which is the municipal waste through the creation of a system based on known processes, is the fundamental advantage of the ERWP model that justifies its application.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Conflicts of Interest:** The author declare no conflict of interest.
