Plastic separation - A review

Plastic recycling is often associated with expensive and complex machines. However, for the plastic separation in low-income countries, a machine as cheap and as less complex as possible is requested, without affecting the separation result. Of special interest is the separation of a binary mixture consisting of polyethylene terephthalate and high-density polyethylene, which are used for beverage and food packaging. Different separation techniques from the literature are reviewed and evaluated for the given use case of plastic separation in Malawi. The evaluation is performed by using different evalu ation criteria, such as performance, costs, and process complexity ratings. Mechanical separation of plastic waste can be divided into two parts: dry separation and wet separation. Whereas the dry separation techniques are seen as more advantageous over the wet technique, as no intense post-processing is required. Air table separation is concluded to be the most suited separation method for the requested separation of plastic flakes in Malawi, followed by other dry separation techniques such as air classification and electrostatic separation. From the wet separation techniques, jigging is evaluated to be the most suitable method. It is proposed how to build a cheap prototype to prove the concept works, and the most important parameters to optimize its performance are listed. A challenge that arises is to reach the minimum quality requirements for polyethylene terephthalate recycling by using only one separation machine, as usually multiple machines are used to remove the different contamination parts.