Post Consumer Plastics Recycling

Phillips, E., Morrow, D., Nosker, T., and Renfree, R. "The Processing and Properties of Recycled Post-Consumer Plastics-Commingled Molding" Proceedings of 1989 RecvclingPlas IV Conference. Plastics Institute of America. Hoboken, NJ. 1989. 

Altland, B. L., Cox, D., Beckerman, E. J. (1995) Optimization of the high pressure, near-critical liquid - based microsortation of recyclable post - consumer plastics. Resources, Conservation and Recycling, 15, pp. 203-217... 

APPR Assoc, of Post-consumer Plastics Recyclers... 

Commercial plastics polymerisation is akin to making pig s ears out of silk purses, albeit usually useful porcine ears from very worn out handbags. What were once valuable polymers are turned into generally less valuable monomers. The regenerated monomers and small chemicals from polymerisation of post-consumer plastics have no particular moral authority or intrinsic grace compared to chemicals derived from non-recycling sources. To be successful, commercial polymerisation must make economic sense in ways that are understood by those who invest dear money into capital assets. 

Post-consumer plastic waste recycling is discussed with special reference to feedstock recycling, the advantages it has over mechanical recycling, and the techniques involved. Chemolysis and thermolysis are explained, and... 

Brief details are given of two proposed resolutions on the subject of pyrolysis of waste plastic. The first states that pyrolysis and other methods of chemically reprocessing post-consumer plastics is a suitable way of diverting waste from landfills. The second resolution, supported by environmentalists, states that pyrolysis only recovers plastic s energy value, and should not be viewed as recycling. 

The high consumption of plastics in developed countries (over 50 million tons in the year 2001 and an increase of 4% year-1 is expected) explains the great interest for exploitation of post-consumer plastics. Taking into account that the environmental regulations prohibit their exploitation by combustion, thermal decomposition or pyrolysis is one of the procedures for recycling plastic with best perspectives for obtaining feedstock and fuel. 

One approach to reduce the contaminant levels consists in reusing the wasted plastic as the core of the new material. Residues of pesticides or harmful contaminants may limit recycling of plastics as a result of their potential toxicity. Utilisation of post-consumer plastics for pharmaceutical or food-contact applications is forbidden, and multilayer food packaging materials manufactured using functional barriers are subjected to strict regulations [9, 40, 41]. 

Huber, M., and Franz, R. (1997). Studies on contamination of post-consumer plastics from controlled resources for recycling into food packaging applications. Deutsche lebensmittel-Rundschan 93(10), 328-331. (In Franz, R., and Welle, F. (2003). Recycling packaging materials. Ch. 23. In "Novel Food Packaging Teclmiques" (R. Ahvenainen, ed.), pp. 497-518. Woodhead, CRC Press, Boca Raton, FL). 

In this chapter the technical as well as legislative aspects of mechanical (secondary) recycling of post-consumer plastics will be described. For packaging materials containing a certain amount of PCR plastics the most important point is the migration of the suspicious compounds from the polymer. 

Feedstock/feed stream Post-consumer plastics used as raw materials for recycling. 

Although direct liquefaction of waste plastic looked promising, problems associated with impurities (paper, aluminum, etc.) and chlorine derived from PVC caused operational difficulties. Consequently, it currently appears that the first step of any feedstock recycling process for waste plastics or tires should be pyrolysis, which allows much easier separation of solid impurities and chlorine. Research on pyrolysis of post-consumer plastic has been carried out by Kaminsky and co-workers [17, 18], Conrad Industries [19, 20], and Shah et al. [21]. Shah et al. [21] conducted pyrolysis experiments on relatively dirty post-consumer waste plastic obtained from the DSD. The pyrolysis oils were then subjected to hydroprocessing to convert them into high-quality transportation fuels (gasoline, kerosene, diesel). 

A distinct advantage of plastic pyrolysis into fuels as a means of recycling is its ability to handle mixed and unwashed plastics. Post-consumer plastics are often commingled and contaminated with extraneous materials such as soil, dirt, aluminium foils, paper labels and food remnants. While soil, dirt and glue can be removed from post-consumer plastics by washing, this is a fairly expensive operation and it leads to secondary waste streams... 

Researchers at the Chehalis facility carried out 18-months of parametric study to assess the Conrad recycling process [9]. Their objective was to identify process bottlenecks, develop operating parameters and begin to assess product value and markets. For the initial experiments a base feed mixture of 60 20 20 high-density polyethylene, polypropylene and polystyrene (HDPE PP PS) was used as representative of the major constituents found in post-consumer plastic streams. 

This chapter describes post-consumer plastic recycling, where recycling refers to plastic material and may involve material recycling, chemical recycling or thermal recycling. 

Recycling is the best alternative. Much of industrial post-consumer plastics can be recycled by some methods because they are sorted. Meanwhile, the range of plastics collected from households is enlarged substantially. It is difficult to recycle unsorted plastics. 

Figure 12.11. Tensile strength of post-consumer plastic containers reprocessed with different fillers. [Adapted, by permission, from La Mantia F P. Recycling of PVC Mixed Plastic Waste, ChemTec Publishing, Toronto, 1996.]...

Develop a robust thermo-catalytic process for producing hydrogen from readily available non-recyclable post-consumer materials and residues, such as spent plastics, organic solid residues, and waste grease. 

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