Incineration is a disposal method that involves combustion of waste material. Incineration and other high-temperature waste treatment systems (also called "thermal treatment") disposes of solid, liquid and gaseous waste. Incineration can be a practical method of disposing of certain hazardous waste materials (such as biological medical waste). While incineration does not completely replace landfilling, it can reduce the volume for landfill disposal significantly.
Energy value of incinerated materials
| Material |
BTU/ lb. |
| Plastics |
11,000-20,000 |
| Rubber |
10,900 |
| Newspaper |
8,000 |
| Corrugated boxes (paper) |
7,000 |
| Yard waste |
3,000 |
| Food waste |
2,600 |
| Average for MSW |
4,500-4,800 |
Source: Tennessee Solid Waste Education Project
Although approaches vary greatly, the incineration sector may approximately be divided into the following main sub-sectors:
- Mixed municipal waste – treating typically mixed and largely untreated household and domestic wastes
- Pretreated municipal or other pretreated waste – installations that treat wastes that have been selectively collected, pretreated, or prepared in some way, such that the characteristics of the waste differ from mixed waste
- Hazardous waste - incineration on industrial sites and at merchant plants (that usually receive a wide variety of wastes)
- Sewage sludge – sewage sludges may be incinerated separately from other wastes in dedicated installations; otherwise such waste is combined with other wastes (e.g. municipal wastes) for incineration
- Clinical waste incineration – dedicated installations for the treatment of clinical wastes, typically from hospitals and other healthcare institutions
Waste-to-energy (WtE) or energy-from-waste (EfW) are broad terms for facilities that burn waste in a furnace or boiler to generate heat, steam and/or electricity. The amount of heat or power produced is highly dependent on the quality of waste being used as fuel. The high (temperature 950-1400 C) achieved by incineration plants allows for generation of steam directly as in a topping cycle.
Close to 35% of total municipal waste is incinerated in Europe, which is much higher than the current 12.7% in the U.S. Also the documented calorific value of municipal waste (approx 13,000 KJ/Kg) is much higher in the U.S. than in most other countries, thus providing better input for incineration.
Incineration-CHP schemes are also suitable in urban locations where there is likely heat demand within a reasonable distance.
Key benefits:
According to a report on waste to energy in Denmark, incinerators reduce the mass of the original waste by 80–85% and the volume (already compressed somewhat in garbage trucks) by roughly 95%, 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. About 10% of the total ash formed in the combustion process is used for beneficial use such as daily cover in landfills and road construction.
Waste incineration in the U.S.
In 2008, about 32 million tons of materials, or 12.7%of total municipal waste generated (249.6 million tons), were combusted for energy recovery.MSW combustion for energy recovery has remained fairly constant since 1990. Over one-fifth of the U.S. municipal solid waste incinerators use refuse derived fuel (RDF). In contrast to mass burning—where the municipal solid waste is introduced "as is" into the combustion chamber—RDF facilities are equipped to recover recyclables (e.g., metals, cans, glass) first, then shred the combustible fraction into fluff for incineration.
Pollution control:
A variety of pollution control technologies significantly reduce the gases emitted into the air, including scrubbers (which use a liquid spray to neutralize acid gases) and filters (which remove tiny ash particles). Burning waste at extremely high temperatures also destroys chemical compounds and disease-causing bacteria. Regular testing ensures that residual ash is non-hazardous before being landfilled.
Specific pollutants from incineration plants have been addressed with new technologies, including the following:
- Pathogens and toxins are destroyed due to high temperatures in the treatment of clinical wastes and certain hazardous wastes
- Dioxins and furan emissions have declined drastically since the 1980s to roughly one-thousandth of their zenith
- Installation of filtering devices has also reduced carcinogenic and non-carcinogenic materials to levels which are comparable to those emitted by conventional power plants
Additional resources: