Patent ID: 8349130

Claim:
A method for removing off gas contaminants from an aqueous evaporation condensate pulp mill effluent stream, which aqueous evaporation condensate contains methanol and off gas contaminants selected from the group consisting of sulphur dioxide and total reduced sulphur (TRS) compounds comprising: providing a hollow fibre membrane contactor comprising a plurality of hollow fibres, each fibre having a hydrophobic membrane wall having first and second opposed sides; flowing the aqueous evaporation condensate through said contactor, in contact with the first sides of the walls of the fibres; and flowing an acceptor fluid through the contactor, in contact with the second sides of the walls of the fibres, allowing said off gas contaminants in said aqueous evaporation condensate to migrate through the membrane walls to said second sides of the walls of the fibres and extracting the undesirable compounds migrating through the membrane walls with said acceptor fluid, while leaving an aqueous methanol stream rich in the methanol of said condensate at said first sides of said walls; said acceptor fluid being selected from a stripping gas or an aqueous alkaline solution.