Matching construction and demolition waste supply to recycling demand: a regional management chain model

Construction and demolition (C&D) waste can be either directly disposed in landfills or processed in recycling plants as aggregates. Depending upon its physical properties, this recycled waste can be used in a variety of construction applications and also reduce dependence on natural aggregates. Since the recycling of C&D waste reduces landfill and conserves natural aggregate resources, most environmental policies aim at increasing C&D recycling. An optimization model is presented to understand the dynamics and planning of a C&D waste recycling network as an integrated set of supply-and-demand chains at the regional level. The model optimizes for minimum costs, includes assessment of technical and environmental performance, and shows the effects of potential policy interventions. A case study using the model revealed that disposal taxes are a cost-effective lever to increase total recycling, but not necessarily high-quality recycling. Increased transport costs reduce the recycling rate considerably, as recycling requires longer transport distances than disposal. The expected strong increase in the supply of C&D waste associated with the population decline (and associated shrinkage) projected for 2050 in Germany requires new sinks, e. g. intensified use of recycled aggregates in concrete, to preserve current high recycling rates.