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Many organizations in Europe collect data and perform research on municipal solid waste and the secondary raw materials that can be produced from them through recycling, urban mining, or landfill mining.However, the information generated and presented thereby is often highly aggregated, while research activities are many a time isolated. Both reduce the usability of the data and information generated. In order to better structure the knowledge generation on secondary raw materials production from municipal solid waste, we suggest to learn from the traditional raw materials mining Industry how to perform an integrated assessment and reporting of anthropogenic resources. This is exemplarily shown for the case of the anthropogenic resource municipal solid waste incineration bottom ash and airpollution control residues. A network of expert institutions from countries throughout Europe was build up to compile the information on legal and technological aspects for the recovery of different secondary raw materials from these residues, including construction minerals, metals, and salts. We highlight in our article the strength of the combined knowledge of an expert network not only on legal and technological, but also local and site-specific aspects of the recovery of secondary raw materials. By doing so, we hope to kick-off a discussion for how to organize and implement a structure for a better management of knowledge on anthropogenic resources, in order to provide a sustainable supply of secondary raw materials for a greener and more circular economy.
An environmentally friendly and cost efficient way for the management of municipal solid waste incineration (MSWI) fly ash represents its thermal co-treatment together with combustible waste. However, the safe introduction and storage of MSWI fly ash in the waste bunker is challenging and associated with severe problems (e.g. dust emissions, generation of undefined lumps and heat in case of moistened MSWI fly ash). Therefore, the aim of this study is to investigate the suitability of pelletisation as a pretreatment of MSWI fly ash. In particular, MSWI fly ash was characterised after sampling, pelletisation and thermal treatment and the transfer of constituents to secondary fly ash and flue gas was investigated. For this purpose, MSWI fly ash pellets with a water content of about 0.15 kg/kg and a diameter of about 8 mm have been produced by disc pelletiser and treated in an electrically heated pilot-scale rotary kiln at different temperatures, ranging from 450°C to 1050°C. The total contents of selected elements in the MSWI fly ash before and after thermal treatment and in the generated secondary fly ash have been analysed in order to understand the fate of each element. Furthermore, leachable contents of selected elements and total content of persistent organic pollutants of the thermally treated MSWI fly ash were determined. Due to the low total content of Hg (0.7 mg/kg) and the low leachate content of Pb (<0.36 mg/kg), even at the lowest treatment temperature of 450°C, thermally treated MSWI fly ash pellets can be classified as nonhazardous waste. However, temperatures of at least 650°C are necessary to decrease the toxic equivalency of PCDD/F and DL-PCB. The removal of toxic heavy metals like Cd and Pb is significantly improved at temperatures of 850°C, 950°C or even 1050°C. The observed metal removal led to relatively high contents of e.g. Cu (up to 11,000 mg/kg), Pb (up to 91,000 mg/kg) and Zn (up to 21,000 mg/kg) in the secondary fly ash. This metal enriched secondary fly ash might represent a potential raw material for metal recovery (e.g. via acidic leaching). Due to the high content of total dissolved solids observed in the leachate of thermally treated MSWI fly ash pellets, a wet extraction procedure is suggested to enable its safe disposal at non-hazardous waste landfills.