Assessing the regional and temporal feasibility of urban-industrial symbiosis: meeting the demand for low-carbon construction materials with urban waste incineration ashes

• The study examines closed-loop urban-industrial symbiosis in ash recycling in the Dutch built environment. • Geospatial analysis with a linear optimization model identifies potential urban-industrial symbioses. • Despite growing recycling and projected decline in cement demand, 16 urban-industrial symbioses remain by 2050. • To foster symbiosis, cities must inform citizens and plan long-term strategies in own waste recycling. While municipal solid waste (MSW) incineration with energy recovery offers advantages over landfilling, it also introduces complexities in aligning with circular economy objectives. As residues of incineration processes, the ashes are currently landfilled in many European countries, while they could potentially be used as supplementary cementitious materials, reducing the demand for carbon-intensive Portland cement. By combining geospatial analysis with linear supply chain optimisation model, this study examines potential urban-industrial symbioses between cities and incinerators in terms of urban waste supply for incineration and distribution of ashes for valorisation in alternative construction materials to meet demand for their urban building stock. Considering circular economy policy recycling targets, population dynamics, and cement demand projections up to 2050, the feasibility of establishing such urban-industrial symbioses over time is assessed in the Netherlands. Examining the 35 biggest cities by population, the results show that under the scenario achieving 75% MSW recycling targets, the capacity of incineration plants becomes excessive in year 2050. However, 16 cities will be able to sustain closed-loop systems both in 2024 and in 2050. This applies to both the supply of MSW for incineration and the fulfilment of urban demand for alternative construction materials with ashes produced from own urban waste, highlighting key areas for fostering urban-industrial symbiosis.