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The quantification of the actual environmental advantage of mechanical recycling of post-consumer PET and PE liquid containers was the main aim of the study. The phases of collection, compaction, sorting, reprocessing and refuse disposal in the Italian system of plastic packaging waste recycling were individually analysed and quantified in terms of energy and material consumptions as well as of emissions in the environment.The results indicate that the recycling scenarios are always preferable to those of non-recycling. The energy saving could be as large as 185% if the energy recovery from scrap wastes is realised. The reduction in material consumption is even very large, indicating, for instance, that in only one year the Italian system for plastic liquid containers is able to save more than 83,000t of crude oil, 28,000t of gas and 23,000t of coal. The calculations were made with the (reasonable) assumption that the final utilization can use the virgin or the recycled polymer without any difference.

Goal, Scope and Background.: The object of the study is the Italian system of plastic packaging waste recycling, active until 2001, that collected and mechanically recycled the post-consumer PE and PET liquid containers. The phases of collection, compaction, sorting, reprocessing and refuse disposal were individually analysed and quantified in terms of energy and material consumptions as well as of emissions in the environment. The work is the result of a joint research project with the Italian Consortium for Packaging (CONAI), carried out in co-operation with the main Italian companies active in the field. The main aim was the quantification of the real advantage of plastic container recycling and the definition of criteria, at the same time environmentally compatible and economically sustainable, for their management. Main Features: For each of the unit processes, and in order to increase the data quality, all the data of interest were collected during technical visits to several selected plants active in Italy or deduced by official documents and certificate declarations of the same companies. To allow comparison of resource consumption and environmental pollution from different management scenarios producing different products, thebasket of products methodwas applied. Results: The results indicates that the production of 1 kg of flakes of recycled PET requires a total amount of gross energy that is in the range of between 42 and 55 MJ, depending on whether the process wastes (mainly coming from sorting and reprocessing activities) were sent or not to the energy recovery. The same quantity of virgin PET requires more than 77 MJ. The energetic (and then environmental) saving is so remarkable, even for PE, being 40–49 MJ for the recycled polymer and about 80 MJ that for the virgin polyolefin. The calculations were made with the reasonable assumption that the final utilisation can use the virgin or the recycled polymer without any difference. Conclusions and Outlook: The analysis defined and verified a suitable tool in the field, based on objective data, for comparing different coherent scenarios of waste management politics. This allows one to propose the extension of the tool under different collection schemes, as well as for different systems of packaging recycling. As an immediate consequence of the success of the present study, the joint-research programme with CONAI has been extended for another three years. The focus will be the Italian system for paper and paperboard recycling and that for all plastic packagings. In parallel, a different study has been scheduled with reference to the integrated solid waste management of the Regione Campania, the largest and most populated area in the South of Italy.

The risk of defluidization during the low‐temperature pyrolytic processes of polyolefins is one of the major constraints to a wider utilization of fluidized beds for the pyrolysis of plastic wastes. A predictive model can estimate the occurrence of defluidization under different operating conditions, taking into account the role of physical properties of the polymers and hydrodynamic variables of the reactor, together with that of the main operating parameters, like the process temperature and the plastic waste feed rate. The results agree well with the experimental data obtained by feeding recycled polypropylene and polyethylene in a laboratory‐scale bubbling fluidized‐bed pyrolyzer. An operating map allows to distinguish the region of reactor stable operation from that of defluidization.

A cold model of a CFB, having a 0.120m ID, 5.75m high riser, was operated at a superficial gas velocity of 6m/s and at average solids mass fluxes varying in the range between 16 and 55kg/sm2. A stream of carbon dioxide was injected continuously at a fixed position along the riser axis and used as tracer gas. Three solids, belonging to groups A and B of Geldart's classification, were selected in order to investigate separately, the effect of particle size and density on the radial mixing of the gas phase. The intensity of radial gas dispersion reduced when larger or heavier particles were used. The differences in the values of radial dispersion coefficient and Peclet number were explained, taking into account the role of the particle size with respect to the scale of gas turbulence.