Assessment of the Recovery Potential of Recyclables via Automated Sorting of Municipal solid waste – A Case Study from Austria

Abstract

Austria needs to increase its effort to transfer more packaging materials to recycling. While the EU recycling targets for 2025 are already met for packaging materials made from glass, paper, and cardboard, a substantial increase in recycling rates is still necessary for plastic and metal. Besides measures such as improving the separate collection and introducing a deposit system for specific fractions, the remaining content of recyclables within mixed municipal solid waste (MSW) could be harnessed. In Austria, approximately 2.3 Mt of mixed municipal solid waste (MSW) are generated. The largest fraction (94%) goes to MSW incineration directly or via residues from pretreatment such as mechanical biological treatment (MBT) or waste sorting. While unburnable materials like glass and metals can also be recovered from bottom ash, plastics and paper are “lost” after incineration and therefore need to be recovered before. According to Austrian MSW sorting analysis, on average, about 17% of packaging materials are in mixed MSW. These 17% of packaging materials comprise 6% plastics, 4% glass, 3% paper and cardboard, 2% metals, and 2% other materials. This investigation, part of a large-scale research initiative called Christian Doppler Laboratory for a recycling-based Circular Economy, aims to assess the recovery potential of recyclables with automatic waste sorting. The assessment includes two Austrian waste sorting plants, with a total capacity of about 330,000 t/a. Their primary purpose is the pretreatment of mixed MSW before incineration. This pretreatment includes shredding, screening, and ferrous- and non-ferrous metal separation. One plant has a two-stage near-infrared (NIR) sorter to produce refuse-derived fuel (RDF) for the cement industry. As a result, only metals are going to material recycling. To assess the recovery potential for other recyclables such as plastics, selected output streams of these plants were sampled periodically and characterized with sorting analysis. Results show that the theoretical recovery potential of plastic packaging from these two plants ranges from 4,800 t/a to 7,000 t/a (not considering sorting losses). Considering that about 300,000 t/a of plastic packaging waste are generated in Austria, from which 76,000 t/a are recycled, those two plants, which treat ~14% of Austria’s mixed MSW, could potentially increase the recycling rate for plastic packaging from currently 25% to 27-28%.