Waste Disposal
There are – broadly – three types of treatments for waste --
Mechanical sorting,
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Heat treatment,
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Biological systems
See the Department for Environmental Food and Rural Affairs (Defra) guide on 'Options for the Diversion of Biodegradable Municipal Waste from Landfill'
Mechanical operations sort, separate, crush – they reduce the waste to something more manageable but don’t eliminate it altogether. Mechanical treatments are often used as the first step in a process which will also involve some form of biological treatment to deal with the compostable part, and some form of heat treatment for the materials left over.
Thermal or Heat treatments mean either burning waste - as in an incinerator; steaming waste in an Autoclave – similar to the type of thing used in hospitals; - or - one of the newer forms of heat treatment called Pyrolisis or Gasification which use heat in the absence of oxygen. All of these processes can, to some extent, create energy or fuel - which can be used for powering other buildings or sold to the National Grid.
And then there’s biological processes. These require careful pre-separation of the waste so that metals and large objects can be removed. Then in controlled conditions, the rotting process can be speeded up so that compost or some other material can be made. The cost effectiveness of these depend on a buoyant market for the resulting products.
See the defra guides listed below for further reading
Advanced Biological Treatment of Municipal Solid Waste
Mechanical Biological Treatment of Municipal Solid Waste
Guidance on Energy from Waste Technology
Incineration of Municipal Solid Waste
Review of the Environmental and Health Effects of Waste Management