Because of its cost-effectiveness against rot, fungi and insects, Chromated Copper Arsenate (CCA) has been widely used for decades as a wood preservative in outdoors residential structures, garden play structures, decking, etc. and industrial structures such as electric poles. Since the late 1990’s, the use of CCA-treated products has declined because of health concerns. The US EPA for example has banned them for residential use, and other countries have banned CCA use altogether. Other chemicals have been used since, containing chlorine, iodine, bromine, or
copper.
There are still many sites containing CCA-treated timber, and when this timber is replaced or removed, it must be disposed of or recycled. Because Arsenic can leach out of CCA-treated wood and pass into surrounding soil (and eventually ground water), CCA-treated wood must be sorted from other wood waste, and kept in a separate, lined
landfill.
Wood can also be incinerated. CCA-treated wood produces ash that is highly concentrated in chromium and copper, and arsenic is released in the atmosphere. Because the ash has become a hazardous waste, it is costly to dispose of. The arsenic must be trapped during the incineration process (which also adds to the cost of the incineration process).
Another option is to dispose of the waste wood at recyclers, who sort it and process it to sell it on (e.g. wood chips, sawdust, etc…).