Optimizing resource efficiency in regional industrial symbiosis: Integrated modelling and scenario analysis

In response to growing environmental concerns and global sustainability efforts, regional industrial symbiosis has emerged as a crucial strategy for enhancing resource efficiency and reducing the environmental impacts of production processes. The concrete industry, being resource-intensive with significant environmental footprints, represents a prime candidate for the application of such symbiotic approaches. By substituting general-purpose cement with treated alum sludge, a by-product of drinking water purification, the sludge-derived green concrete has the potential to markedly lower its embodied carbon. However, achieving widespread adoption necessitates a comprehensive evaluation of industrial symbiosis and logistic optimisation to ensure eco-economic viability. This study explores critical aspects of alum sludge treatment and develops a genetic algorithm (GA)-based tool to strengthen the symbiotic relationship between the water and concrete sectors, with a focus on decarbonizing sludge-derived concrete while maximising its economic returns. Eight scenarios were assessed, highlighting the environmental and economic advantages contributed by regional industrial symbiosis. Results show that pre-treating alum sludge at water treatment plants can lead to a carbon reduction of up to 86.24%, alongside potential energy and cost savings of approximately 65.16% and 52.04%, respectively. When factoring in landfill cost avoidance, total savings could exceed 100%. For sludge-derived concrete with a 10% cement substitution, energy savings and carbon reductions were recorded at 2.57% and 5.53%, respectively. Furthermore, the GA-based tool effectively identified optimal treatment locations or the nearest drinking water treatment plants based on market demand of sludge-derived concrete, thereby aligning environmental benefits with economic gains. Highlights : • Sludge-derived concrete promotes sustainability through reginal industrial symbiosis between water and concrete sectors. • An integrated model has been established to support the assessments of eco-economic performance and resource efficiency. • A GA-boosted framework has been developed to optimize eco-economic benefits of sludge-derived concrete production. • Scenario analysis conducted to explore decarbonization potential and cost-saving opportunities. • Supply chain optimization applied to enhance eco-economic viability within a regional industrial symbiosis framework.