June 5 – 10, 2022
Today about 80 million tonnes of municipal solid waste (MSW) is annually incinerated in Europe. One of the solid residues from the municipal waste incineration (MSWI) plant is fly ash (FA). FA is classified as hazardous waste due to the high content of soluble salts, potentially toxic elements (Zn, Pb, Cd, Cr, Cu, Hg, Ni, As, and Sb), and trace organic pollutants (e.g. dioxins, furans, etc.) and, therefore, must be disposed of in special landfills . On the other hand, the high content of valuable components (Zn, Pb, Cu, and salts) makes FA a potential anthropogenic source for resource recovery. In addition, the production of FA usually accounts for 10-30 kg/t of incinerated waste. Nowadays, 0.75 million tonnes of waste in the Czech Republic is incinerated annually and about 0.02 mil. tonnes of FA produced. With the future limits of landfilling in the EU, the volume of FA will increase. Finding environmentally friendly pathways to promise the use of FA concerning the Green Deal, Circular Economy, and Sustainability goals of EU are critical to future developments in this sector. The study aims to identify and evaluate the potential environmental impacts (EI) or benefits of the viable pathways of MSWI FA treatment in the Czech Republic. EI are evaluated using the Life cycle Assessment (LCA) approach based on Product Environmental Footprint (PEF 3.0) methodology. The 5 cases of MSWI FA treatment pathways will be comparatively assessed for FA taken from 3 different Czech MSWI plants. The first case represents cement-based S/S of FA with landfilling of solidificates as non-hazardous waste. The second case describes the water washing of FA for removal and recovery of soluble salts and landfilling of residues as non-hazardous waste after cement-based S/S. The last three cases illustrate three different options of recovery of valuable metals (Zn, Pb, and Cu): acid extraction of metals followed by their chemical precipitation as a filter cake, acid extraction followed by electrochemical recovery of pure metals, the combination of water washing for recovery of salts followed by acid extraction of metals with their chemical precipitation. The remaining solid residues from these three cases are landfilled as non-hazardous waste after cement-based S/S, similarly to the first two cases. The evaluation is performed using GABI and OPenLCA software with specific databases (Sphera – 2021, Ecoinvent, ILCD, EF, Exiobase, etc.). The results of selected impacts (such as climate change, acidification, photochemical ozone formation, water consumption, ecotoxicity, etc.) are presented and compared with published data from international studies and databases. In addition, the potential circular economy indicators of by-products will be evaluated. The analysis is focused primarily on the operation phase. The life cycle inventory (LCI) includes the transportation of MSWI FA by truck from the MSWI plant to its disposal on an above-ground landfill. For all cases, the impacts of the transport of the necessary operating media (cement, acids, etc.) are included. The functional unit is defined as 1 tonne of MSWI FA for the treatment and disposal. For the cases, the recommendation from the study  is considered for possible transfer into the environments (more specific to air, soil, and aquatic) and validated with data obtained from databases. Input and output process flows are defined with the conclusions obtained from experimental verification of MSWI FA treatment supplemented by balances and data from international published studies, journals, and reports. In the end, two approaches of distributions of EI into by-products will be analyzed and compared. The first is the form of credits as a replacement for identical products from raw materials. In the second approach, the PEF 3.0 of the MSWI, including FA treatment, will be divided into each product based on allocation, i. e., techno (mass, exergy), economic (market price/cost), or circular indicators.  Yuying Zhang, et al., Treatment of municipal solid waste incineration fly ash: State-of-the-art technologies and future perspectives, Journal of Hazardous Materials, Volume 411, 2021, 125132, ISSN 0304-3894, https://doi.org/10.1016/j.jhazmat.2021.12  Huber F, et al., Comparative life cycle assessment of MSWI fly ash treatment and disposal. Waste Manag. 2018 Mar;73:392-403. doi: 10.1016/j.wasman.2017.06.004. Epub 2017 Jun 9. PMID: 28602425
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Monika Vitvarova, Ekaterina Korotenko, Vladimir Koci, and Michal Syc, "Environmental aspects of the implementation of MSWI fly ash treatment methods in the Czech Republic" in "WasteLCA_3: Life Cycle Sustainability Assessment For Waste Management And Resource Optimization", Umberto Arena, University of Campania “Luigi Vanvitelli”, Italy; Thomas Astrup, University of Denmark, Denmark Eds, ECI Symposium Series, (2022). https://dc.engconfintl.org/lca_waste_3/53