Almost 500 municipal solid waste incineration plants in the EU, Norway and Switzerland generate about 17.6 Mt/a of incinerator bottom ash (IBA). IBA contains minerals and metals. Metals are mostly separated and sold to the scrap market and minerals are either disposed of in landfills or utilised in the construction sector. Since there is no uniform regulation for IBA utilisation at EU level, countries developed own rules with varying requirements for utilisation. As a result from a cooperation network between European experts an up-to-date overview of documents regulating IBA utilisation is presented. Furthermore, this work highlights the different requirements that have to be considered. Overall, 51 different parameters for the total content and 36 different parameters for the emission by leaching are defined. An analysis of the defined parameter reveals that leaching parameters are significantly more to be considered compared to total content parameters. In order to assess the leaching behaviour nine different leaching tests, including batch tests, up-flow percolation tests and one diffusion test (monolithic materials) are in place. A further discussion of leaching parameters showed that certain countries took over limit values initially defined for landfills for inert waste and adopted them for IBA utilisation. The overall utilisation rate of IBA in construction works is approximately 54 wt%. It is revealed that the rate of utilisation does not necessarily depend on how well regulated IBA utilisation is, but rather seems to be a result of political commitment for IBA recycling and economically interesting circumstances.

Austria must recycle more packaging materials. Especially for plastic packaging waste, significant increases are necessary to reach the EU recycling targets for 2025 and 2030. In addition to improving separate collection and introducing a deposit system for specific fractions, the share of plastic packaging in mixed municipal solid waste (MSW) could be utilized. In Austria, about 1.8milliontonnes of mixed MSW are generated. This includes about 110,000 t/a of plastic packaging waste. Most of the mixed MSW (94 %) is sent directly or via residues from pre-treatment, such as mechanical-biological treatment or waste sorting, to waste incineration. While materials such as glass and metals can also be recovered from the bottom ash, combustible materials such as plastics must be recovered before incineration. This work aims to evaluate the recovery potential of plastic packaging waste in mixed MSW with automated waste sorting. For this purpose, two of the largest Austrian waste sorting plants, with a total annual throughput of about 280,000 t/a, were investigated. The investigation included regular sampling of selected output streams and sorting analysis. The results show that the theoretical recovery potential of plastic packaging from these two plants is 6,500 t/a on average. An extrapolation to Austria results in a potential of about 83,000 t/a. If losses due to further treatment, such as sorting and recycling, are considered, about 30,000 t/a of recyclate could be returned to plastic production. This would correspond to an increase in plastic packaging recycling rate from 25 % to 35 %.

Bottom ash is the primary solid residue arising from municipal solid waste incineration. It consists of valuable materials such as minerals, metals and glass. Recovering these materials from bottom ash becomes evident when integrating Waste-to-Energy within the circular economy strategy. To assess the recycling potential from bottom ash, detailed knowledge of its characteristics and composition is required. The study at hand aims to compare the quantity and quality of recyclable materials present in bottom ash from a fluidized bed combustion plant and a grate incinerator, both located in the same city in Austria and receiving mainly municipal solid waste. The investigated properties of the bottom ash are grain-size distribution, contents of recyclable metals, glass, and minerals in different grain size fractions, and the total and leaching contents of substances in minerals. The study results reveal that most recyclables present are of better quality for the bottom ash arising at the fluidized bed combustion plant. Metals are less corroded, glass contains fewer impurities, minerals contain fewer heavy metals, and their leaching behavior is also favorable. Furthermore, recoverable materials, such as metals and glass are more isolated and not incorporated into agglomerates as observed in grate incineration bottom ash. Based on the input to the incinerators more aluminum and significantly more glass can potentially be recovered from bottom ash from fluidized bed combustion. On the downside, fluidized bed combustion produces about five times more fly ash per unit of waste incinerated, which is currently disposed of in landfills.

Through the Circular Economy Package, the EU aims to reduce material imports and environmental impacts of waste management. Ambitious recycling targets should help to achieve these objectives. As a response, the waste industry developed technical and organizational solutions that can intervene at different stages of a waste management system in order to increase the recovery of recycling materials, starting with improved separate collection over the use of modern material recovery facilities up to the enhanced treatment of waste incineration ashes. The large question is how each of these options can contribute to increase recycling rates to achieve a circular economy. By reviewing case studies as presented in the most recent literature published since the year 2010 from European countries on the recycling of post-consumer packaging waste of glass, metals, paper, and plastics, this study contributes to answer this question. In the first stage, the review found 644 articles matching with the search terms and published since the year 2010. Of these, 46 remained for an in-depth analysis, since 319 did not present case studies as defined in the scope of this article. The articles reviewed provide a good overview on the state of knowledge on increasing recycling of post-consumer packaging waste by improved separate collection, material recovery facilities, and waste incineration bottom ash treatment. Additional information and case studies, however, are required, particularly large-scale experiments to test new separate collection systems, large-scale with different feedstock material at the most-modern material recovery facilities and waste incineration bottom ash treatment plants.

Enhanced treatment of incineration bottom ashes (IBA) from municipal solid waste incineration can contribute to a circular economy since not only metals can be recovered but also glass for recycling. Moreover, the remaining mineral fraction can be utilized in concrete as manufactured aggregate. To evaluate the effects of an enhanced treatment, three IBAs from fluidized bed combustion (FB-IBAs) and three grate incineration bottom ashes (G-IBAs) were standardly treated in a jig and further processed on a pilot scale, including improved metal recovery and sensor-based glass separation. The removed glass fractions were weighed and their composition was assessed by means of manual sorting. The manufactured aggregate was also sorted manually and its total and leachate contents were determined before and after aging. Results showed general differences between FB-IBAs and G-IBAs. For G-IBAs, higher contents of heavy metals and residual metal pieces were determined, while the share of glass removed was low compared to FB-IBA. The treated mineral fractions from G-IBA contained more mineral agglomerates, whereas FB-IBAs contained more glass. However, the glass-fractions removed from FB-IBAs need further treatment to be accepted in glass recycling. Austrian limit values for utilization in concrete were met by all manufactured aggregates produced from FB-IBA, but only by one from G-IBA. Overall, the enhanced treatment in the study performed well compared to the literature. Nevertheless, further investigations are necessary to improve the recyclability of the recovered glass fractions and to determine the technical suitability of manufactured aggregates produced from IBAs.

Urban buildings consume raw material and energy, and they produce waste and greenhouse gasses. Sustainable urban development strategies aim to reduce these. Using the case study of buildings in Vienna, this article evaluates the impact of a defined urban development pathway on the heating energy demand, greenhouse gas emissions, and total material requirement of buildings in Vienna for 2021–2050. Furthermore, the impact of recycling to reduce the total material requirement and to increase the circular material use rate is evaluated. The results show that the heating energy demand can be reduced to meet the targets of Vienna’s sustainable development strategy. The same does not count for greenhouse gas emissions. To meet the targets for the latter, the renovation of old buildings by thermal insulation should be expanded and heating systems substituted. With respect to the total material requirement, the recycling of demolition waste from buildings in Vienna to produce secondary raw materials for buildings in Vienna can help to achieve the reduction targets of Vienna’s sustainable development strategy so that in the year 2050, the material footprint is only 44% of the value of the year 2019. Since there is a contradiction between the total material requirement and the circular material use rate, the latter has to be discussed for its use as a circular economy indicator, since the aim of circular economy is not to produce as much recycling materials as possible, but to reduce resource consumption to a sustainable level.