Abstract. Plastics are exceptionally useful materials for all kinds of consumer items, but poorly managed plastic waste breaks down in smaller pieces contributing to land and ocean pollution with microplastics and nanoplastics. Rapid growth in global plastic production over the last decades increased to 368 million metric tonnes in 2019. Manufacturers utilize a variety of different plastic materials that each possess unique properties. While plastics have been recycled since the 1970s, the quantities that are recycled are relatively small. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities. Combined actions of the public, industry and governments can divert the majority of plastic waste from landfills to recycling and reuse over the next decades. Most popular and commonly used plastics are: PolyΜethyl Methacrylate, Polycarbonate, High and Low density Polyethylene, Polystyrene, Polypropylene Polyethylene Terephthalate, Polyvinyl Chloride or Vinyl. Some plastics are easily recyclable but some are very challenging and need special chemical methods to break down their chemical bonds and produce monomers of oil fuels. Mechanical recycling of plastic waste is generally the most cost effective approach, however with some limitations. The profitability and economic viability of mechanical recycling depends on the type of plastic material and the degree of contamination of the waste stream. Additionally, there are many technological applications for chemical recycling of plastic waste that are very effective and low cost. Chemical recycling addresses the plastic waste that cannot be mechanically recycled for technical or economic reasons. Chemical recycling offers a variety of technological solutions for plastic waste which is either more contaminated, or mixed and/or consist of multi-materials. The thermal and catalytic decomposition of waste plastic through pyrolysis is one of the best approaches of handling plastic waste. In the last decade large number of research initiatives have developed for biocatalytic technologies to recycle of post-consumer plastics. Enzymatic biocatalysis has gained increasing attention as an eco-friendly alternative to conventional plastic treatment and recycling methods. Bioremediation of plastics waste using engineered enzymes has emerged as an eco-friendly alternative approach for the future plastic materials as a form of circular economy with low waste and recycled feedstocks. Scientists found that enzymes in the wax worm can biodegrade polyethylene (PE), most commonly used in plastic bags. Researchers of Spanish National Research Council and the University of Cambridge showed that the worms were able to break the polymer chains in PE by eating them. The second most important chemical technology, after pyrolysis, is gasification, where plastic waste is reacted with gasifying agents at high temperature around 500–1300 C. Hydrothermal liquefaction (HTL) is another recycling process that emerged for the valorization of biomass and applied to plastic waste recycling to provide energy recovery and low molecular weight chemical products.
http://chem-tox-ecotox.org/wp-content/uploads/2022/05/PLASTIC-RECYCLING-2022.pdf