Plastics collection/cleaning/separation

Recycling of postconsumer plastics involves the process of collection, cleaning, separation, and then processing them into various products. These different steps will be elaborated in the following sections. 

Separate collection of plastics, sorting, cleaning and mechanical recycling. 

Special collection systems are generally provided for large-scale or commercial postconsumer applications such as for agricultural films, chemical containers, automotive parts, carpets, and polystyrene foam packaging. Since most of the plastic is collected as multimaterial or in commingled forms, the collected plastic waste has to be sorted, separated, and cleaned, and most of this is done at material recovery facilities (MRFs). 

Treatment and recovery of plastics mixtures is more difficult. For example, about 3%-5% of household rubbish consists of plastics mixtures. Such mixtures can indeed be cleaned, reduced, and directly processed but the end products obtained in this way, however, have very poor mechanical properties because of the incompatibilities of polymers contained in the mixture. The subsequent sorting of plastic mixtures by hand is expensive and not reliable. Even the separate collection of old plastics is uneconomic, and indeed, even with unpaid volunteers. On the other hand, utilization of the thermal content of plastics as an energy source during rubbish combustion is economic, since the amount of oil required for complete combustion is reduced. 

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. 

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