Material flow, economic and environmental assessment of municipal solid waste incineration bottom ash recycling potential in Europe

• Published in: Journal of cleaner production 2021-10, Vol.317, p.128511, Article 128511
• Main Authors: Bruno, Martina, Abis, Marco, Kuchta, Kerstin, Simon, Franz-Georg, Grönholm, Raul, Hoppe, Michel, Fiore, Silvia
• Format: Article
• Language: English
• Subjects: Bottom ash; Circular economy; Municipal solid waste; Recycling; Thermal treatment; Waste-to-energy
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2021.128511

In 2018 municipal solid waste (MSW) incineration in Europe produced nearly 19 Mt of bottom ash (BA); only 46 %-wt. was treated, often in poorly performing plants, leaving behind 10 Mt of untreated and unrecovered BA, destined to landfill. This work was based on the inventory of BA across Europe, and on the hypothesis to achieve complete BA valorisation through two assumptions: treating 100% BA and minimizing the loss of valuable fractions due to technical limitations of state-of-the-art processes in comparison to advanced innovative processes. The research involved three phases: characterization of potential secondary raw materials (metals and mineral fraction) currently lost from untreated (the surplus compared to treatment capacity) and unrecovered BA (the fine fraction) through material flow analysis; environmental assessment (energy balance and net GHG emissions) of complete BA valorisation; investigation of the economic feasibility of complete BA valorisation through state-of-the-art technologies. The resulting 2.14 Mt loss of valuable materials included 1 Mt mineral fraction and 0.97 Mt ferrous metals, mostly from untreated BA, and 0.18 Mt non-ferrous metals, mostly from unrecovered BA. The energy balance and GHGs emissions required by the treatment of the currently untreated and unrecovered fractions of BA resulted in energy and GHGs emissions savings. Economic profitability was driven by iron and copper recycling and avoided landfill fees. Profitability was achieved by two thirds of considered countries (average values: NPV 83 M€, ROI 20%, payback time 11 years) with BA mass flow exceeding 0.02 Mt. [Display omitted] •Untreated and unrecovered bottom ash (BA) in Europe in 2018 (10 Mt) were analysed.•A technical/economic/environmental assessment of complete BA valorisation was made.•Energy balance was positive and net GHG emissions were negative in all countries.•Economic profitability was due to Fe and Cu recycling (1.15 Mt) and avoided landfill fees.•Economic profitability was achieved when BA mass flow exceeded 0.02 Mt per year.