Incineration is a waste treatment technology that involves the combustion of organic materials and/or substances. Incineration and other high temperature waste treatment systems are described as "thermal treatment". Incineration of waste materials converts the waste into incinerator bottom ash, flue gases, particulates, and heat, which can in turn be used to generate electric power. The flue gases are cleaned of pollutants before they are dispersed in the atmosphere.
The term has found its way into the petroleum marketing industry because at some facilities, at some gasoline stations, unwanted gasoline vapors are burned instead of being transported back to a terminal for conversion into liquid gasoline.
At such stations, equipped with Stage II vapor recovery systems, the incineration unit is usually located on top of the station building. Vapors collected by the Stage II system are routed to this unit, ignited, and burned off.
Incineration with energy recovery is one of several waste-to-energy technologies such as gasification, Plasma arc gasification, pyrolysis and anaerobic digestion. Incineration may also be implemented without energy and materials recovery.
In several countries there are still expert and local community concerns about the environmental impact of incinerators.
Incinerators reduce the volume of the original waste by 95-96 percent, depending upon composition and degree of recovery of materials such as metals from the ash for recycling. This means that while incineration does not completely replace landfilling, it reduces the necessary volume for disposal significantly.
Incineration has particularly strong benefits for the treatment of certain waste types in niche areas such as clinical wastes and certain hazardous wastes where pathogens and toxins can be destroyed by high temperatures. Examples include chemical multi-product plants with diverse toxic or very toxic wastewater streams, which cannot be routed to a conventional wastewater treatment plant.