The I-US model and indicators were finalized, including an optimization model comparing centralized and decentralized ash supply chains, and creating a sustainability indicator framework. The model has been applied to pilot regions through interviews and data collection to evaluate the costs, benefits, and business cases for I-US. A digital LCA-GIS tool has also been created to assess environmental and economic impacts using different I-US models, incorporating spatial data and ongoing updates with real pilot data. Lastly, the final version of Ash Modeling Application (AMA) software, developed by AI4Value, is now deployed and in maintenance phase. This software allows LCA optimization and matching ash characteristics to application requirements. AMA remains available for project partners until end of the project.
75 ash samples have been collected and characterized. This data provides crucial information for resource recovery potential and product development. The ash pretreatment method using sodium hydroxide effectively mitigates expansion and cracking caused by metallic aluminum. Carbon sequestration capacity has been assessed. Results showed that fly ashes generally have higher sequestration potential than bottom ashes, though actual CO2 uptake varies with curing conditions, highlighting the need for further optimization.
A literature review was prepared, focusing on phosphorus and metals recovery from ashes. Waste-acid extraction and electrochemical techniques were identified as feasible approaches. A pilot-scale electrodialytic separation (EDS) cell system was successfully developed. EDS experiments conducted by DTU demonstrated successful extraction of heavy metals and rare earth elements (REEs) from various ashes, achieving over 75% extraction for metals like Cd, Cu, Zn, and Pb under optimized conditions, and over 90% for certain REEs in stirred set-ups. Metal recovery from EDS-treated solutions using reduction crystallization and electrowinning methods was studied. Ash-based adsorbents developed showed preliminarily promising results for removing phosphate and ammonium from water. Finally, the safe removal of hazardous elements like Ni, Cd, and As that cannot be economically recovered was assessed, with precipitation at varying pH being tested and MgO-functionalized geopolymers considered for enhanced immobilization.
The mix designs for using ashes as supplementary cementitious materials in Portland cement concrete, alkali-activated concrete binders, carbstone products, fired or unfired clay bricks, and granulated ashes for earth construction have been optimized. The optimized mix designs met structural and durability standards, and thus are ready for the semi-industrial trials and pilots.
8 out of 11 large-scale pilots have been completed.
An overview of applicable legislation and standards for each application or product was collected. AshCycle partners advanced regulatory and environmental validation for ash-based construction products. ZAG and UNIZG led standardization efforts, leaching tests, and technical assessments for market approval.
