Plastic wastes mechanical recycling

This article provides brief information from a study carried out in the Netherlands, which revealed that combustion with energy recovery is the most economical way of processing waste plastics, whilst mechanical recycling is the most environmentally attractive option. 

Plastics waste comes from two main sources processing plants (ca. 10%) and post-use scrap (90%). The former is nearly totally reprocessed (i.e., > 96%) by the processors using the plastics (or mechanical) recycling methods. Recycling of the later material very much depends on the... 

The products are recovered from the MS W stream via curbside collection, separated/ sorted at MRFs, and then cleaned and ground into chips at plastic reclaiming facilities to be remelted into recycled resin pellets. The recycled resin is used, mixed with virgin plastics, in the fabrication of plastic products. Mechanical recycling works best when applied to source-separated streams of waste plastics products. 

Recycling additives Impact modifiers, stabilizers Used to improve/protect properties of waste plastics during mechanical recycling... 

Post-consumer recycling process occurs when plastics are made into products, for example, bottles, bags, film, packaging, used by a consumer, collected by a waste disposal company, processed into recycled pellets at an MRE, and then sold to plastic companies. Mechanical recycling is the most common recycling method for plastics. 

Finally, other relevant treatment options for plastics waste include landfill and mechanical recycling. Since these options (unlike Vinyloop and cement kiln incineration) are not even similar to feedstock recycling we discuss them here only very briefly. Mechanical recycling of plastics (be it PVC or other plastics), needs dedicated collection of the plastic waste in question. This is only possible for selected plastic flows (high volumes, recognisable products, products consisting mainly of one plastic). Landfill can accept plastic waste in any waste context (pure plastic type, MPW, mixed materials). I will only address the costs of these alternative technologies. 

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... 

This paper analyses the difficulties of the two traditional plastics waste recovery routes, energy recovery and mechanical recycling, and goes on to introduce a third... 

Mechanical recycling is the preferred route for homogeneous and relatively clean plastics waste streams. It is assumed that the cushion vinyl floor covering will be mechanically recycled [11].1... 

The building and construction plastics account only for 3% of overall collectable plastic waste in Western Europe in 2002, of which about 8% is mechanically recycled within Europe on a regular basis. However, the building and construction sector is an important end market for recycled plastics from many sectors. Some 30% of overall recycled plastics are used in applications such as insulation, fences and flooring. 

Besides mechanical recycling, the conversion of waste plastics into a petrochemical feedstock is another way for the recovery of the organic materials from a polymer waste. A basic problem is the removal of organobromine compounds. 

The changes in mechanical properties due to degradation and/or blending, contamination, antioxidant consumption and general use (e.g. oxidation processes) of the polymeric material during first service life are some of the characteristics that determine if the material should be recycled mechanically or disposed of in another way (e.g. energy recovery). A successful recycling is strictly dependent on the purity and uniformity of the plastic waste. 

Feedstock or chemical recycling is seen as complimentary to mechanical recycling and seems appropriate for cost effective treatment of mixed and contaminated plastic waste streams (115). A progress report, on potential technologies for high PVC content mixed plastic waste streams, is available (21). Promising developments, which look technically and economically viable, are ... 

This report discusses the options for feedstock recycling of plastics waste, including aspects of the environmental and economic pros and cons relating to feedstock recycling in comparison with incineration or mechanical recycling of municipal solid waste, based on a number of life cycle assessments. Particular reference is made to the experience of the TNO-CML Centre of Chain Analysis.485 refs. 

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