Circularity indicator for municipal solid waste treatment plants

Abstract

Circular Economy (CE) has become an essential paradigm to achieve sustainability, and waste processing plants are an important element to minimise loss of resources in the production and consumption system. To incorporate CE into decision-making processes, it is essential to have metrics that consider this criterion. To date however, no such indicators can explicitly allow the circularity of waste treatment plants to be assessed straightforwardly. The objective of this study was to develop an indicator to measure the circularity of municipal solid waste (MSW) treatment plants (TP). This work is based on a literature review about efficiency indicators for resource recovery, an analysis of the most used technologies of such plants, and their materials and energy balances. As a result, a new circularity indicator for treatment plants (CITP) is proposed that combines two components: the main one evaluates the material recovery efficiency, and the secondary one quantifies energy recovery. Following the waste management hierarchy, for equality in the first component's value, the alternative with the highest energy component would be better evaluated. CITP was applied to six case studies ranging from a landfill with gas recovery to an MSW processing facility that includes the recovery of materials and the use of rejects as alternative fuel. The analysis of case studies reflects that the best MSW treatment alternatives must contemplate the intensive recovery of recyclable materials and the energy use of combustible rejects. The application results show that CITP can be calculated simply with the required information easily available, which enables different alternatives to be compared as regards CE and leaves the room for improvement of each alternative to be easily identified.