Engineering insights into thermal plasma processing for plastic waste management: a review

Abstract

The rapid accumulation of plastic waste due to its non-biodegradability and increasing global consumption presents a significant environmental challenge. Conventional thermochemical waste management techniques, such as pyrolysis and gasification, offer partial solutions but suffer from secondary pollutant formation, inefficiencies, and scalability issues. Thermal plasma-assisted processes, operating at extreme temperatures of 1,500–5,000 °C, present a promising alternative by leveraging high-energy plasma arcs to achieve complete waste destruction, converting plastic into syngas and inert slag while minimizing hazardous by-products like dioxins and tars. Despite being studied over decades, the commercialization of plasma technologies remains limited due to high capital costs, proprietary technology barriers, and suboptimal reactor designs. The scalability of these systems depends on optimizing energy efficiency and feedstock adaptability, which can be addressed through advanced reactor design. This review systematically evaluates thermal plasma technology for plastic waste treatment through chemical engineering analysis of plasma-specific reaction kinetics under rapid heating conditions, coupled heat/mass modelling in high-temperature reactors, and computational optimization of torch configurations and reactor geometries. Key knowledge gaps are analyzed, including electrode erosion dynamics, plasma gas selection trade-offs, unaddressed radiation effects, and lack of thermal plasma-specific kinetic-modelling and experimentation, while presenting strategies to overcome these limitations through both modeling and experimental approaches.