Advancing quality of recycling assessment: a new multidimensional indicator streamlining computation and communication

While the importance of high-quality recycling is emphasized in European acquis, assessing the quality of recycling remains a challenge. Advancing recent work on the subject, a new multidimensional indicator is presented and applied to the case of two waste materials of the Construction and Demolition Sector: glass and brick. The indicator assesses the quality of recycling considering three dimensions (Technical, Temporal, and Environmental) providing a qualitative outcome. A 3D diagram is developed where each axis represents one of the three dimensions such that the space under study is totally included in a cube. Each of the three axes of the cube is divided into two sections via a threshold value, resulting in eight sub-cubes corresponding to eight qualitative levels of quality. The results for the two case studies show the potential of the indicator. Concerning glass, two pathways were evaluated: a closed-loop process (flat glass-to-flat glass) and an open-loop process (flat glass-to-recycled aggregates). When the indicator is applied, the former option resulted in a High-Quality level, whereas the latter in a Low-Quality one. For the bricks, three different open-loop recycling pathways were assessed: replacement of cement, recycled aggregates, and alkaline activation. The recycled aggregates pathway resulted in a Medium-High-Quality 3 level, whereas the other pathways in a High-Quality one. Since it can be applied to any combination of recycling pathways and waste material fractions, the indicator shows potential to function as a decision-support tool for industry and policymakers, building on and advancing previous attempts by streamlining calculation and communication.