Page last updated at 11:23 GMT, Tuesday, 14 February 2006

Q&A: Waste incineration

Waste is tipped into a holding area (1) where it is picked up by grabs and dropped into a hopper (2).
The waste is pushed gradually into the incinerator (3) which runs at a temperature of 750 degrees Celsius.
Heat from the burning waste is used in a boiler (4) and steam from this is piped to a turbine generator to create electricity.
The heaviest ash falls into a collection point (5) and is passed over with an electromagnet to extract metal content for recycling.
Flue gases containing fine ash then pass through a scrubber reactor (6) to treat acid pollutants such as SO2 and also dioxins.
The gases then pass through a fine particulate removal system (7) and are released through the chimney stack (8).

The UK government has launched a review of its waste strategy. Among the proposals is a plan to increase the amount of rubbish that is incinerated instead of being sent to landfill sites.

The BBC News website looks at the arguments for and against the use of incinerators.

Q. How much waste is currently incinerated?

Around 9% of municipal waste in England is currently incinerated.

The south-west has the lowest proportion of incineration, with less than 1% being burned.

The West Midlands burns the most, sending 31% of the region's waste to incinerators.

The vast majority of municipal waste is still sent to landfill sites. Around 72% of the 29.1 million tonnes of rubbish was buried in 2003/04.

Q. Why are environmentalists and campaigners against more incinerators?

They say incineration encourages more waste because incinerator operators need to have a constant level of waste to keep the fires burning.

To meet this demand, campaigners say, local authorities abandon recycling and waste reduction plans.

However, government figures show that recycling and composting of waste increased in 2003/04 by 3.3% to 19%.

Campaigners are also concerned about pollution from the smoke and ash, which they say is a health risk to local residents.

Q. What are the possible health risks?

The main concern surrounds pollutants found in the ash left in the incinerator and emitted from the chimney.

These include dioxins, acid gases, nitrogen oxide, heavy metals and particulates.

It is the dioxins contained in the gases from the chimneys that attract most concern because they are suspected of causing cancer.

The Environment Agency in England and Wales, and the Scottish Environment Protection Agency regulate and closely monitor the emissions from incinerators.

The introduction of tighter EU regulations in 1996 saw many of the older incinerators close down because they could not meet the stricter standards.

Q. What are the benefits of incineration?

Nearly all of the municipal waste that is burned in the UK is used to generate electricity, in what is called "energy from waste" (EfW).

If the waste is not burned then it is likely to end up in a landfill site which is considered the least environmentally friendly option.

Ash from incinerators can be used in the construction and road building industries.

Environmental groups say that although incinerators generate electricity, it does not save energy in the long run because the waste is not recycled. This means more raw materials have to be produced to replace the burnt material.

Q. How much waste does the UK incinerate in comparison to the rest of Europe?

Around 17% of waste in the EU is incinerated, almost twice the UK level.

Denmark, seen by many as one of Europe's most environmentally conscience nations, burns around 53% of its municipal waste.

At the other end of the scale, a number of countries - including Ireland and Greece - do not incinerate any of their waste.

Review launched to tackle waste
14 Feb 06 |  Science & Environment

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