Draft PPS18: Renewable Energy
Annex 1 Energy from Waste (Thermal Processes) Technology: Disposal of Ash and Gas Cleaning Residues
There are two types of ash from conventional incinerators. The ash that falls from the combustion grate (bottom ash) is inert and can be sent to normal landfill. The ash from the flue gas cleaning installation contains heavy metals and traces of other contaminants and should be sent to controlled landfill. The ash from gasification and pyrolysis plants may contain a higher carbon content but this is not thought to be harmful as the carbon is in its elemental form and inert. Heavy metals will still be found in the finer ash and may need disposal in controlled landfill. This will depend upon the process and appropriate treatment of this ash will be a condition of the licence to operate.