Identification and sorting systems

Most collection schemes generate heterogeneous material streams, which must be efficiently sorted to provide generic material streams. Frequently-used sorting methods are  

Macro sorting can be performed at the source of waste by giving directives to the consumers as in kerbside collection schemes. It is also carried out on an 

1 PETE = poly-ethylene terephtalate (PET) 2 HOPE = high density polyethylene 3 V = vinyl/polyvinyl chloride (PVC) 5 PP = pol)rpropylene 6 PS = polystyrene 7 OTHER = all other resins 

Such national coding systems may be superseded by the international ISO 14000 standard on material coding (see Chapter 6). There are several drawbacks to these attractively simple systems, of which the most significant is the variety of molecular weights and additives in plastics made from the same base polymer. This can create difficulty in maintaining the required quality of the material stream. 

Automated identification and separation technology is necessary to reduce the cost of recycling and enable greater volumes of waste to be processed. 

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