The optimal management of the Solid Waste (SW) treatment system is still a crucial issue, since it involves political choices other than technological, social and economic factors. After the collection, the material streams are directed into the different treatment paths: the recycling plants for the separated material streams (e.g. paper, plastics, glass, metals) and the Mechanical Biological Treatment (MBT) plant for the Residual Unsorted Waste (RUW). The system outputs are the recycled manufactured products, the Refused Derived Fuel and the rejected materials from recycling plants. The calculation of the exergy cost (or Embodied Exergy, EE) of the processes appears a useful tool for accounting the resources invested in each step of the chain. Moreover, the enlargement of the system boundaries, with the inclusion of alternative scenarios for virgin materials production, allows the calculation of the avoided or additional exergy and monetary costs. Exergy indicators are developed and used for comparing different scenarios of waste recovering. Finally, a Multi-Objective Optimization is performed for seeking the best trade-off solutions, considering both the exergy efficiency and the total monetary cost; the optimization variables are linked to the amount of recycled materials. Results show that, even if the total recycling option is the best in matter of rational use of resources, trade-off solutions can be find for intermediate scenarios with moderate costs increment.