Occurrence and formation of environmentally persistent free radicals in incineration and their impact on soil and water

Incineration is a thermal waste treatment technique that can be understood as a controlled combustion process with the primary objective of volume reduction of waste mass. Combustible waste including gaseous, aqueous, muddy, molten, and solid waste is typically deal with incineration at temperature ranges from 750 to 1200 degrees C. End products of incineration include a considerable amount of particulate matter (PM) and pollutants. Particulate matter released from the incineration process plays an important role in forming environmentally persistent free radicals (EPFRs) which are the most toxic and stable substance emitted from the incinerator. Other major compounds released during the incineration process are dioxins, polychlorinated biphenyls, polychlorinated naphthalene, chlorinated benzenes, and polycyclic aromatic hydrocarbons (PAH). Although incineration is significantly used to control the waste crisis but emissions of toxic substances from an incinerator have various health impacts on the environment and humans. Long exposures to these hazardous compounds lead to respiratory and cardiovascular diseases. These toxic compounds participate in various redox activities as well as metal complexation events and deteriorate the physiochemical parameter of soil and water. The aim of the present study is to summarize the existing knowledge regarding the formation of harmful compounds released during waste incineration and major environmental challenges associated with them.