Separation of plastic waste from mixed waste: Existing and emerging sorting technologies performance and possibilities of increased recycling rate with Finland as case study

The current world view of the production, usage and disposal of plastics, especially flexible plastic packaging, is that of a tale that has generated several environmental and sustainability issues. In excess of 7% of world fossil, a non-renewable resource, is used as feedstock and energy for the production of plastics. Over 250 kt of waste plastics may already be floating and contaminating the world’s seas leading to the death of thousands of marine life and other animals; with an estimated 10% microplastics capable of finding their way into the food chain. The ever-increasing demand for plastics products, is liable to significantly increase these figures in the not too distant future. However, advances in technologies and systems for the collection, identification, sorting, separation and reprocessing of recyclable plastics are providing new prospects for recycling to closing the loop. Recycling provides opportunities to reduce oil, gas and coal usage; greenhouse gas emissions; the unleashing of plastics debris into the oceans and other water bodies; and the quantities, by volume and weight, of waste requiring disposal. Challenges involved in the collection, separation and sorting systems of plastic wastes have effectively limited it recycling rate and consequently made it arguably the least recycled waste stream; yet it is the most plentiful (i.e. by volume) of post-consumer wastes. In recent years, automated sorting has influenced and changed the way plastic wastes are segregated from other waste fractions and contaminants. This study examined how emerging and existing automated separation technologies performance could help impact and further improve the recycling process and caused corresponding significant increase in recycling rate. With Finland as case study, the focus was on the collection and utilization of mixed residual waste from municipal solid waste; and how processing this stream using separation technologies with high performance could help increase the recycling rate of plastics fraction (i.e. polymers) present in the stream. Ensuing case results suggested that with a source separation efficiency of 40-60%, it is possible to recover for recycling nearly half (i.e. 48%) of the total plastic packaging present in the mixed residual waste. This further increased plastic packaging recycling rate by 29. In this wise, it made about 102000 additional tonnes of plastic packaging available for recycling. Total plastic waste amount in the residual waste was found to be 16.8% of the total mixed residual waste. The derived recycling rate of 29% for plastic packaging corresponded to total plastics recycling rate of 24% with prospect for further possible increase.