Method for recovering a wood preservative from waste sludges

摘要

The present invention provides a method for the recovery of a wood preservative chemical from aqueous waste sludges containing said wood preservative chemical in both its liquid and solid phases. The method comprises treating said aqueous waste sludges to effect an initial separation and recovery of the liquid and solid phases, individually. The recovered liquid phase comprises the first liquid phase product stream. The recovered solid phase then is subjected to elevated temperatures sufficient to liquefy the solid phase, said liquefied solid phase comprising the second liquid phase product stream. During the liquefaction of the recovered solid phase, it may be contacted with a quantity of a fresh wood preservative chemical, a portion of a dehydrated first liquid phase product stream or a portion of a dehydrated second liquid phase product stream to prevent the precipitation of any normally solid constituents therein and to enhance the liquefaction of said recovered solid phase.