Sustainable Treatment Strategies for Waste Plastics: Pathways Towards Resource Recovery and Clean Energy

Abstract

Plastic production now exceeds 400 million tonnes per year. Plastic waste persists due to its chemical stability and resistance to biodegradation. It accumulates in both terrestrial and aquatic ecosystems until it eventually fragments into microplastics, which pose ecological and human health risks. Current plastic waste management practices, including mechanical recycling, landfilling, and incineration, have limitations associated with the logistics of collecting contaminated feedstock, material compatibility, sorting efficiencies, and the greenhouse gas emissions produced during the non-recoverable portions of these materials. As a result, there is a strong push towards developing more environmentally sustainable plastic waste management technologies and practices aligned with circular economy principles. In this chapter, alternative methods of plastic waste management are reviewed, specifically focusing on the use of thermochemical conversion of plastics through pyrolysis, gasification, liquefaction and chemical recycling. A review of published life cycle assessments (LCAs), comparing the impact categories of global warming potential, fossil resource depletion, and human toxicity for mechanical recycling, pyrolysis, gasification, liquefaction, and chemical recycling is also included. Additionally, an analysis of current trends regarding plastic waste generation globally as well as locally in various regions and how they relate to technology availability and government policies is presented. A case study of the Indian context provides insight into the role of the informal recycling industry and how different types of recycling (i.e., mechanical recycling, regulated thermal treatments, open burning) create trade-offs.