ABSTRACT
While plastics recycling has been practiced for many years with focus on homogeneous industrial scraps and homogeneous post-consumer plastics, the industry also accepted the challenge of recycling heterogeneous plastics waste based on new technologies of separation and processing. The present chapter deals with both these aspects of recycling and discusses various methods of waste plastics disposal, used in practice, with their merits and demerits. Different recycling methods currently available for predominant polyethylene terephthalate (PET) wastes, namely direct reuse, reuse after modification, glycolysis, methanolysis, ammonolysis, hydrolysis, depolymerization in supercritical fluids, and enzymatic depolymerization, are discussed. Other homogeneous wastes discussed similarly are polyurethanes, poly(vinyl chloride), and cured epoxies. For mixed wastes of plastics, methods considered are various direct use technologies, separation into single materials for reuse, and liquefaction for converting into oil. Considering its magnitude, importance, and several unique problems that it presents, rubber tire recycling is treated elaborately. Recycling methods of car batteries are reviewed. Equipment and machinery commonly used for various steps in waste plastics recycling operation, including automatic sortation, are described. The new concept of upcycling (as opposed to “downcycling” or recycling) of waste plastics is reviewed. Focus is also given on issues associated with plastics waste disposal, advantages and disadvantages of landfill, gas recovery prospects, impact of biodegradable plastics, composting, and energy generation by incineration.
