Operating Experience of ECF Bleaching with Xylanase Treatment

Abstract

Yonago mill of Oji Paper produces approximately 1, 200 tons of hardwood pulps per day at 85-86% ISO brightness for coated paper products.Xylanase treatment with on-site enzyme production was introduced into the hardwood kraft pulp bleaching process (C-E/O-dnD) in October 1998. A thermostable xylanase from a microorganism. Bacillus sp. S-2113, that we isolated through screening was selected for use in this process. The xylanasecontaining culture was applied to the bleaching process without removing the bacterial cells from the culture medium. Therefore. xylanase treatment process could be operated economically. Introducing xylanase treatment was allowed to reduce bleaching chemicals, so chemical cost was lower than before.In Novenber 2000, the bleaching process was converted to ECF one (D0-E/O-dnD). As a result, effluent AOX and chloroform emissions have decreased significantly. It is recognized that introducing xylanase treatment is allowed to reduce bleaching chemicals in ECF bleaching process, too.