Patent ID: 6425974
Filing Date: 2002-07-30
Classification: C02F,D21C,Y10S

Abstract:
A process for reducing the amount of dissolved organic compounds in waste water discharged from a bleach plant, said waste water comprising alkaline wash filtrate from treatment-steps and/or delignification/bleaching-steps of pulp, said process comprising:i) treating at least a part of the alkaline filtrate in order to produce an alkaline concentrate enriched in high molecular weight dissolved organic compounds and a stream depleted in organic compounds, where the share of the alkaline concentrate to the total amount of the alkaline filtrate corresponds to a volume reduction factor in the range of from about 2.0 up to about 7.5, ii) withdrawing the depleted stream, iii) collecting at least a part of the alkaline concentrate from step i) and using the concentrate as wash or dilution water in brownstock washing fiberline with a dilution factor of up to about 4.0, where at least a part of said washing filtrate is brought to the chemical recovery system.