Poly recycling incineration

In Japan the amount of waste poly(vinyl chloride) (PVC) has been sharply increasing since disposal of building materials such as pipe and roof liners with long service life has been started recently. It was estimated to be approximately one million tons in FY 2000, and it is predicted to increase further to approximately 1.8 million tons in FY 2020. Since the landfill sites run short and the incineration to reduce its volume produces dioxins and corrodes boiler tube by hydrogen chloride, development of a safe and inexpensive technology for the recycling of waste PVC is one of the most urgent issues. 

Other materials in waste that is thermally processed also were studied by pyrolytic techniques, typically with the purpose of regenerating the monomers or of obtaining other useful small molecules. For example, pyrolytic studies were performed for the evaluation of the possibilities for re-utilization of nylon carpet waste [7], the recycling of thermoset polymeric composites [8], the recovery of methyl methacrylate from poly(methyl methacrylate) waste [9], as well as for other raw material recovery from pyrolysis of plastic waste [10]. The results of incineration of various other types of waste also were studied at model scale [11, 12). These studies were applied to specific waste materials associated with the manufacturing process or to municipal solid waste [13-15)... 

The pyrolysis process for waste recycling is frequently done at larger scale than analytical pyrolysis. However, analytical pyrolysis studies are performed independently for the understanding and the optimization of such processes [10,16-19]. Also, model mixtures can be used in parallel with real samples. For example, the comparison of thermal degradation products from real municipal waste plastic and model mixed plastics can help understand the compounds generated in waste incinerators. In one such study [20], analytical pyrolysis of real municipal plastic waste obtained from Sapporo, Japan and model mixed plastics was carried out at 430 °C in atmospheric pressure by batch operation. The chlorinated hydrocarbons found in degradation liquid products of poly(ethylene)/poly(propylene)/ poly(styrene)/poly(vinyl chloride) and other polymeric mixtures were monitored. It was determined that the presence of poly(ethylene terephthalate), in addition to chlorinated plastics in the waste, facilitates... 

An ideal way to recycle waste plastics is to remelt them and form new products directly, bnt this process is usually possible only in the case of rather homogeneous waste streams. With heterogeneous plastic-containing waste streams, however, because other processing steps would be required, landfilling and incineration are the most favored disposal methods from an economic point of view. These disposal processes can lead to environmental problems, especially in the case of halogen-containing plastics snch as poly (vinyl chloride) (PVC). 

The opponents of thermal recycling are concerned with the environment the presence of too high a proportion of poly(vinyl chloride) in the plastic waste, if the incineration is not carried out correctly, can lead to the presence of dioxins in the flue gase there is also concern that the energy used in manufacturing the polymer is not recovered. 

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