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Table1. Grades of waste wood within the UK system, derived from [33].
Notes
The main sources for this type of wood are the distribution, packaging, and retail industries (e.g., pallets, packing cases, cable drums), as well as offcuts from the wood machining industries. The wood can be contaminated with nails, screws and plastics; however, the processors generally screen these out. The wood can contain minor amounts of surface paint, but these are commonly water-based and non-toxic. This is the preferred material for animal bedding applications, but can also be used by the panelboard industry, in non-IED Chapter IV biomass, or in the manufacture of briquettes and pellets. This can include Category A wood and demolition wood and material from waste transfer stations. It can, therefore, include solid wood furniture. This grade of wood can be contaminated with plastics, paints, glass, grit, non-hazardous coatings, and glues. This is the preferred material for the particleboard industry but can also be used for IED Chapter IV biomass. This can include Categories A and B but is primarily sourced from municipal collections, transfer stations and HWRCs. This category often contains wood-based panels from flat pack furniture and DIY products. It can include some treated wood (non-CCA and no creosote). It can be used in panelboard manufacture or burnt. Due to the presence of the water-based preservatives any incineration needs to be in a boiler compliant with Chapter IV of the Industrial Emissions Directive. This category is a ‘waste’ according to Waste Management Regulations. This category includes waste wood from hydraulic engineering (e.g., from docks) or from industrial applications (e.g., cooling towers, or woodblock flooring), and from boats, carriages, and trailer beds. Can also be waste wood treated with CCA or creosote (i.e. includes telegraph poles, agricultural fencing, etc). The wood can contain all the contamination found in Category C, but the presence of CCA (Copper Chrome and Arsenic) preservatives and creosote is the main criterion. It must be segregated and consigned to sites permitted to handle hazardous wood.
Pre-consumer waste wood and untreated wooden packaging Clean untreated wood
CategoryA
Business waste Treated non-hazardous
CategoryB
Municipal waste wood Treated non-hazardous
CategoryC
Hazardous waste wood Treated hazardous Category C and track works, fencing and transmission poles
CategoryD
The grades were developed by the Wood Recyclers Association and have been refined as the waste wood handling sector has matured [33]. The difficulties of separation and classification (relating to the unknown provenance and history of the wood) are largely handled by the route that the wood takes entering the recycling system and the improved recognition and testing of the wood that is deemed potentially hazardous. The largest chal- lenge remains when handling wood waste at household waste recycling centres (HWRCs, for domestic waste) as the wide range of products being disposed of makes recognition difficult. A testing programme in 2019–2020 indicated that the percentage of hazardous waste entering HWRCs was so low that it could be considered insignificant (0.06%). A follow-up round of testing was initiated in 2023 to provide additional evidence [34]. A guidance document was released in November 2021, giving clear examples of wood types commonly handled at HWRCs, and which ones are most likely to potentially contain
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