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Incineration Plants
Different incinerators are used to treat different types of waste. All are strictly monitored and must comply with European Directives on incineration. The local authorities or the Environment Agency ensure that all emission limits are met. Plants are regularly reviewed to ensure that emissions are reduced over time as the technology allows and as legal limits are tightened.
Hazardous Waste Incinerators
Hazardous waste incinerators primarily treat dangerous wastes from industrial sources, including the chemical and pharmaceutical industries, paint, food factories and metal processing operations.
There are two types of hazardous waste incinerators: merchant or in-house. ESA·s Members are responsible for the two operational merchant hazardous waste incinerators in the UK. These facilities treat about 100,000 tonnes of hazardous waste each year between them. It is estimated that there are approximately 60 in-house incinerators in the UK, but these are usually small, dedicated units.
Municipal Waste Incinerators
Municipal waste incinerators treat all types of municipal waste, burning the waste at high temperatures to reduce the volume of the waste and produce energy.
All municipal waste incinerators in the UK generate energy from waste facilities which treat between 80,000 - 600,000 tonnes each year. Efw facilities in the UK currently recover value from approximately 9% of municipal waste.
Clinical Waste Incinerators
There are currently about 250 incinerators in the UK which deal solely with clinical waste, mainly in hospitals. Clinical waste includes waste from hospitals, dentists, veterinary surgeries, nursing homes, etc. These wastes pose a significant threat to human health as they may contain waste tissue, blood, dressings, and other contaminated material. Chemical waste generally cannot be treated or disposed of by landfill or other processes.
Sewage Sludge Incinerators
Currently, approximately 20% of sewage sludge (2.4 million tonnes) is incinerated in the UK. Incineration is usually carried out in multiple hearth or fluidisied bed systems, sometimes after mixing with municipal solid waste. The calorific value of dewatered sludges is typically sufficient to give self-sustaining combustion.
Pyrolysis and Gasification.
New technologies also offer the potential to recover other products from the waste stream which complete combustion would not allow. A number of these processes, such as pyrolysis and gasification, are under development at the moment, and a significant proportion are focusing on biomass waste.
- Pyrolysis involves heating waste in the absence of oxygen at temperatures of 400-800°C. The heat breaks down complex molecules and resultant gases are then passed into a combustion chamber where they are heated (in the presence of oxygen) at temperatures around 1250°C. The process produces a liquid oil which is used as a fuel.
- Gasification involves heating wastes in a low-oxygen atmosphere to produce a gas with a low energy content. This gas can then be burned in a turbine or engine.
Combined Heat and Power
Combined Heat and Power (CHP) systems can make incinerators more energy efficient providing energy and heat for local communities and businesses. A number of the UK·s efw facilities have a CHP system in place, but the absence of appropriate infrastructure restricts its use at other facilities. CHP is particularly suited to facilities which are close to new housing developments or industrial parks where a heating scheme can be incorporated at an early stage of construction. 
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