Municipal solid waste incinerator ash

[edit] What is municipal solid waste incinerator ash ?

The incineration of municipal solid waste (MSW) involves the burning of organic materials at very high temperatures, often to reduce the waste bulk and produce energy from the hot gases. The result of burning municipal waste or any material is the production of two types ash, a light, fine ash called fly ash and heavy ash called bottom ash, together they are referred to as municipal solid waste incinerator ash (MSWIA).

On average, the total ash produced through combustion is around 10% in relation to the volume of the input materials, and around 30% in relation to the weight of the input materials. Of the total ash that is produced typically about 10-20% (by weight) of the ash produced is fly ash, the rest 80-90% is bottom ash.

Municipal solid waste (MSW) was estimated at 1.3 billion tons per year worldwide in 2012 and is expected to rise to 2.2 billion tons by 2025. So theoretically that is around 22 million tons of ash globally by volume. Around only 15% of incinerators globally are waste to energy plants (or incineration with energy recovery), of which 80% are in nations such as Japan, France, Germany and the United States.

[edit] Fly Ash

Fly ash (also called flue ash) is a general term given to the lighter fine ash that is produced during the combustion of any material in a furnace or incinerator, it is normally around 5-10% of the mass of the material being burnt. The density of this light ash can vary anywhere between 550 to 850 kg/m3, it is kept in suspension during combustion and often accumulates on the sides of chimney flues, or many cases is collected through special filtration systems placed within the flue.

Fly ash is also commonly associated more directly with the combustion of coal, where it maybe referred to as pulverised flue ash or PFA. It is a by-product of specifically the coal combustion process, particularly electricity generating power stations. It is formed when fine particulates of burnt coal fuse in suspension and are driven out with flue gases. As they are driven out of the combustion chamber, the fused material cools and forms glassy particles called fly ash. Modern coal-fired power plants use particle filtration equipment to catch the fly ash before it reaches the chimneys.

[edit] Bottom Ash

Bottom ash or main ash as the name suggests collects at the base of an incinerator, it is the equivalent of ashes left behind after lighting a simple fire. It tends to be higher density but can be anywhere between 700 and 1200 kg/m3. Bottom ash can be used Bottom ash is used as a construction material in artificial reefs, roads, liners, and daily covers for landfills, concrete masonry blocks, and lightweight and partial replacement of aggregate.

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