Waste Incineration Directive (WID)
The 'thermal treatment' which includes combustion, gasification and pyrolysis of solids or liquids that can be defined as waste ('which the holder discards or intends or is required to discard') is governed by the Waste Incineration Directive (WID). Guidance on the WID is available from Defra (Environmental Permitting Guidance The Directive on the Incineration of Waste). The guidance states that 'for the purposes of the WID 'waste' has the same meaning as in the EC Waste Framework Directive (WFD)', however there is no definitive list of what is and is not waste beyond the statement above, leaving courts to be the final arbiter.
In addition, experimental plants that are used for research, demonstration and testing, and also treat less than 50 tonnes of waste per year, are also excluded from the WID.
Even plants that are excluded from the WID by virtue of the fact that they only treat excluded wastes may still require a Pollution Prevention and Control (PPC) Permit, a Waste Management License or an Exemption.
Under very limited circumstances waste derived fuel (WDF) may cease to be waste before it is used as fuel if it has been subject to some form of processing, however, this is subject to ruling by courts and is not expected to apply in many cases.
Thermal conversion of treated wood waste, as well as other industrial wastes and co-products, is most likely to be covered by the WID. In addition, material defined as 'hazardous waste' is subject to specific constraints under the WID. Timber from construction and demolition sites is also assumed to be covered by WID unless it can be shown to be otherwise.
The WID imposes requirements on the types of waste permitted at a given plant, delivery and reception of the waste, the thermal conversion equipment used and the operating conditions required, abatement plant, emissions monitoring requirements and emission limits values to air and water. Disposal of ash is not specifically covered by the WID, however, other EU legislation is relevant, such as the Landfill Directive. Waste is defined as either non-hazardous under the WID (according to the European Waste Catalogue) or hazardous, and the technical requirements of the processing plant are different in each case.