The paper analyses an Integrated Solid Waste Management System potentially suitable for a real Romanian metropolitan area where selective collection is still in development. From the analyzed integrated system, each technological solution taken into account is focused on the following data: waste composition (proximate and ultimate), energy potential, processes efficiency, net energy generation. The paper presents the first results of mass and energy balances with special attention on the separation process of the residual municipal solid waste. Taking into account the local needs and environmental standards, the presented approach considers the following options that separate the waste in different flows: selective collection for some sellable materials and residual municipal solid waste collection, mechanical treatments and combustion process. In practice, the system pre-treat the waste in order to separate some materials that the present selective collection system cannot recycle (because of its low efficiency). Applying this system 85% of the initial waste energy will be used for energy recovery. An increase of 10% in the LHV is observed thanks to mechanical pre-treatments. The system allow the minimization of landfilling (only 10%) thanks to pre-treatments that extract low LHV materials.