Electrodialytic Removal of Cu, Cr and As from Treated Wood

The service life of wood treated with Chromated Copper Arsenate (CCA) may be 30 years or even more due to the strong fixation of CCA in wood. The strong fixation also means that when the wood is removed from service, a large proportion of the copper, chromium and arsenic is still present and will enter into the waste stream unless actions are taken to prevent this.

While the use of CCA is regulated in many countries, the handling of the waste wood is often not. The amount of treated wood being removed from service is expected to increase dramatically over the next few decades. A method for safe handling of the waste wood and reuse of the wood resources, the contains — energy and metals, — would be environmentally beneficial.

Here we tested electrodialytic remediation as a remediation method. Preliminary results show that more than 90% copper and approximately 85% chromium and arsenic are removed from the wood. When the method will be optimised, it is expected that close to 100% of the metals will be removed during remediation.

Afterwards the metals can be recovered and possibly reused in new wood preservatives. The wood chips can be reused or burned as it no longer contains metals.