In a previous research developed by authors, it was published a methodology for estimating the energy content of the residual fraction refused by the Zaragoza´s mechanical–biological treatment (MBT) plant located in Zaragoza, Spain. The present study is based on a developed environmental evaluation method, that uses the Life Cycle Assessment (LCA) methodology, with the aim to evaluate the environmental implications, in terms of net CO2 emissions equivalent, of the valorisation of this residual fraction, taking into account the CO2-equivalent (eq.) emissions produced by the collection system, including transport stages, the MBT plant and the CO2-eq. emissions avoided by the Municipal Solid Waste (MSW) recovery (energy and material) method used. As a case study, the MSW management system in the ecocity Valdespartera, which is attended by the Zaragoza’s MBT plant, has been studied, taking into account a stationary vacuum waste collection and transport system for approximately 10,000 homes. Based on the application of the developed methodology to the case study, the environmental implications of the valorisation of the residual fraction refused by this MBT plant, which collects residual household waste from 62 municipalities in four regions of Aragon – Zaragoza, Ribera Baja del Ebro, Campo de Cariñena, and Campo de Belchite, are evaluated. Results allow detecting significant technical and environmental findings that could be used for promoting essential changes in the upstream of the MBT plant. Also, these results are relevant to help municipal decision makers in order to develop energy and material recovery, and disposal programs.