AshCycle project outline

The EU funded AshCycle project (June 2022 - May 2026) provided tools for reducing the waste generation from the incineration of municipal solid waste (MSW), biomass, sewage sludge, or combinations of them by developing new utilization possibilities. The project deployed exemplary pilot solutions of the Industrial-Urban Symbiosis (I-US) concept by demonstrating novel recovery methods for valuable elements from the ashes. Furthermore, the aluminosilicate-rich minerals recovered from the ashes were piloted as a feedstock for companies across value chains to obtain products for construction and wastewater treatment leading to increased resource efficiency and circularity.

The AshCycle project had a broad cross-sectorial symbiotic approach as there were companies involved from, for example, waste management, energy production, ash processing, construction material manufacturing, water treatment, and information technology. On the other hand, the project also featured cross-cutting solutions for the material recovery from ashes and utilization of the mineral residues. Moreover, a cloud-based digital tool was developed to embed modern artificial intelligence (AI) and machine learning (ML) algorithms in such way, that they can be used by ash producers. With this tool, ash producers can utilize modern modelling methods to evaluate quality and optimal utilization potential of their ashes.

To fully realize the I-US concept also the engagement of citizens, civil society and end users were addressed in the project.

The objectives

The specific objectives of the project were

• to develop a software for ash producers (Ash Modelling Application, AMA) to evaluate the utilization potential of different ashes based on their composition and properties, and to predict the ash quality based on online measurements of power plants.
• to decrease waste generation from incineration processes by avoiding the landfilling of ashes and to decrease ~20 Mt/year of CO2 emissions by developing construction materials from the mineral residue of ashes.
• to validate and demonstrate AshCycle technologies and products.
• to identify and address the sustainability performance of innovative products and technologies, taking into account their safety and functionality.
• to engage and improve knowledge exchange between all relevant stakeholders in the value chain to develop synergies, partnerships, and new business opportunities in developing the ash-based I-US with also focusing on non-technological barriers.
• to collaborate with European Community of Practice and other circular I-US funded under the same topic, in order to establish an effective and sustainable platform towards building new circular value chains and disseminate the major innovation AshCycle outcomes and best practices.
• to communicate results and engage with the expectations about the future utilization prospects of underutilized ashes and to create the awareness among external stakeholders and the general public across the EU. Special focus will be given on better integration of I-US concepts and developed different AshCycle technologies and products within local communities through social innovation spin off activities such as workshops, showcases, public events, e-learning platform, videos etc.

Concept and methodology

The AshCycle overall concept was to develop new utilization prospects for currently underused and largely landfilled ashes leading ultimately to (near-)zero waste. In project, the ashes were characterized, categorized, and pre-treated to enable the recovery of valuable elements and to obtain high quality aluminosilicate-rich mineral residue for subsequent utilization. The use of the mineral residue was validated and demonstrated for construction material and wastewater treatment adsorbent applications. A focal point of the project was to develop regional I-US value chains for the ash utilization in pilots and to demonstrate their replicability - not only from technical aspect but taking into consideration several non-technological barriers, as well as environmental, economic, and social points of view. Value chains were created in each regional pilot or replication case (Denmark, Finland, Belgium, the Netherlands, Croatia, Slovenia, Switzerland, and South Africa) for waste valorisation and up-cycling. Each area gathered all relevant and important value chain stakeholders needed to implement economic, social, political, technical, and environmental dimensions of the I-US concept.

The project began with characterization of ashes from each regional pilot in terms of their quantities, chemical, physical, and mineralogical properties. In addition, the existing ash quality data of the powerplants was utilized. Based on the characterization, ashes were categorized into different groups in terms of their critical properties. The groups were rated where a lower level indicates more efforts needed for pre-treatment before utilization. Optimized pre-treatment methods for different groups of ashes were selected with the aim of improving the ash quality to enable economically viable recovery of valuable elements and subsequent utilization of the remaining mineral residue in low-carbon circular construction materials or adsorbent materials. Also, the carbon sequestration and storage capacities of ashes were evaluated by accelerated carbonation to stabilize ash and to reduce CO2 emissions. After pre-treatment, novel recovery methods were validated and demonstrated. The recovered valuable elements were further concentrated and their direct industrial use is evaluated.

The above mentioned ash characterization and pre-treatment data, together with existing databases and information available from scientific publications, was used as an input for the development of a cloud-based digital tool called AMA (Ash Modelling Application). The AMA software enables power plants to use AI-based modelling to evaluate required pre-treatment of ashes to achieve optimal utilization potential. It can also be used to evaluate replication potential of the AshCycle concept in other regions than the demonstrated pilot sites. The LCA/GIS tool was integrated with AMA to assess the environmental impacts of ash utilization along value chains in proposed applications.

The mineral residue of ashes remaining after recovery of valuable elements were used for the development of low-carbon circular construction materials and products. Another utilization prospect for the mineral residue was to develop alkali-activated composite adsorbents. Different utilization options were validated on laboratory-scale experiments and optimization of the products. Then, each product was demonstrated in a full-scale regional I-US pilot involving several actors from the value chain and in several replication demonstrations, which were performed as semi-industrial pilots or as computational-only virtual replication. Some virtual replications also included laboratory- or bench-scale testing of the AshCycle I-US concepts to support calculations. 

The pilots took place in three main areas: Croatia and Slovenia; Netherlands and Belgium; and Finland and Denmark. The demonstration projects involved inter-regional cooperation and relied on close cooperation between the local community, the industrial sector, universities and R&D institutions. Demonstration projects served as models for the successful implementation of the new solutions in the market, enhancing the capacity of the whole society to accept new concepts, technologies and procedures. They were designed to serve as models with high replicability and scalability potential.

In addition to the technical aspects, the AshCycle project also evaluated the I-US concept from economic, environmental, and social points of view. The symbiotic set-ups between different actors within the water-energy-waste nexus were modeled using the information from pilots. Moreover, the most appropriate set of indicators was selected to measure the overall societal impacts such as the level of system circularity integrating the frameworks, the level of inter-sectoral activity, environmental, economic, and the social impact. Technical and non-technical barriers were assessed with realistic business cases in collaboration with involved stakeholders, and measures to mitigate them were proposed.