Municipal Solid Wastes (MSW) that contain mixtures of paper, wood, green wastes, food wastes, plastics, leather, and rubber can have energy characteristics similar to wood. Use of MSW as a fuel can be accomplished by burning the as-received material, called mass burning, but processing is often required before it can be burned effectively. The purpose is to reduce size and remove materials, valuable materials or non-combustible materials in order to be reclaimed and used as alternative fuel for sustainable disposal and converted into green and clean energy. The impact of burning these heterogeneous materials in traditional boiling systems, as primary or supplemental fuel, needs to be assessed: the physical and chemical characterization of raw materials should be performed. “Solid Recovered Fuels” a classification system is used based on RDF main parameters: lower heating value, chlorine and mercury content. The ideal composition of RDF is high content in plastics, paper/cardboard, polymeric containers textiles, wood and other organic matter. Higher heating value is in fact associated with paper/card, plastics, wood and textiles content and, once these materials have in their composition biogenic compounds (40-80% w/w), they become an interesting alternative fuel to accomplish the reduction of CO2 emissions. Moreover, meaningful advantages of RDF are its low production costs and significant calorific value. The drawback associated to these fuels is their heterogeneity, moisture and high ash, chlorine or sulphur content associated with energetic density, ignition, combustion and corrosion problems in boilers. Several benefits of using RDF in the cement industry blended with other fuels are expected, namely ecological, with the reduction of the non-renewable fossil fuels and its environmental extraction impacts, the reduction of greenhouse gases emissions. It is also important to notice that the wastes would otherwise have to be disposed of on waste disposal sites. The technical benefits enclose the organics destruction at high furnace temperatures and residence times and the reduction of non-combustible parts of raw materials. The energy recovery from wastes can be achieved by direct combustion, gasification or pyrolysis, with the first being more generally allocated. Nevertheless, pelletizing should be implemented once it is the potential way for mass and energy densification of these energetic materials. In the economic standpoint, in the cement industry, as fuel consumption decreases the production costs also reduce. The purpose of this study is to characterize the rejected streams from the mechanical treatment of unsorted municipal solid waste, from the rejected residual fraction from plastic municipal selective collection and from the rejected fraction from the composting treatment, in order to evaluate their potential of valorization as RDF.
