A critical review on thermal treatment technologies of combustible fractions from mechanical biological treatment plants

The presence of combustible fractions (CFs) such as plastic, paper and cardboard, textiles, wood, leather, and rubber in municipal solid waste (MSW), which are incalcitrant to microbial activities, has become a limitation for their utilization through biochemical processes. This results in the creation of MSW heaps within the premises of municipalities of developing nations, which leads to land scarcity, leaching of toxic species, and negative impacts on the surrounding inhabitants’ health. In this context, the panacea is the bulk utilization of CFs as a manmade resource. Several attempts have been made by the researchers to utilize the CFs as refuse-derived fuel (RDF), a resource/feedstock for thermal treatment technologies such as incineration, pyrolysis, and gasification. However, the utilization of CFs in the above-mentioned applications is facing issues associated with the material quality, operational parameters, and residual disposal, which ultimately defy the upscaling process. Therefore, this review presents the (i) current status of incineration, pyrolysis, and gasification (ii) influence of operating parameters (especially process temperature) on the product yield and quality, (iii) future scope for research in thermal treatment, (iv) perspectives on the thermal treatment in developing countries, and (v) future byproduct utilization schemes as a manmade resource for sustainable development. Additionally, the relationships proposed between the operating temperature (of the pyrolysis and gasification process) and product yields and calorific value are useful for practitioners while deciding the operating conditions of the field scale plants.