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Closing the household metal packaging cycle through recovery of scrap from waste-to-energy bottom ash: The case study of Flanders

Van Caneghem, J., De Coster, E., Vandenbergh, K., De Broyer, S., Lambrix, N., Weemaels, L.
Resources, conservation, and recycling 2019 v.144 pp. 115-122
bags, bottom ash, case studies, markets, material flow analysis, metals, packaging, recycling, uncertainty, wastes, Belgium
In 2015, in Flanders, 45 279 t of household metal packaging was brought on the market, of which 25 639 t was separately collected via the dedicated waste bags after consumption. Literature data showed that 16 880 t of the household metal packaging was present in residual waste that is incinerated in waste-to-energy (WtE) plants; together with the separately collected waste corresponding to 93.9% of the household metal packaging brought on the market. Metals that are present in the incinerated waste largely remain in the bottom ash. A representative sorting experiment showed that the different metal scrap fractions recovered from WtE bottom ash consisted for 2.2 to 11.3% of packaging. Combining these percentages with waste and bottom ash mass flows pointed out that only 2 577 t of metal packaging was present in WtE bottom ash, together with the metal packaging separately collected corresponding to an overall recycling rate of 62.3%. The difference between the household metal packaging mass flows obtained from literature data and from the sorting experiment is remarkable, even taking into account the uncertainty on the results of the sorting experiment and those due to assumptions made in the material flow analysis and the possible material losses to other ash fractions in the WtE process. It shows the need to gather more accurate information on the composition of the different household waste streams and of all WtE ash fractions to establish realistic recycling rates.