Ways to reduce the amount of organically bound chlorine in bleached pulp and the AOX discharges from ECF bleaching

摘要

The formation of chlorinated structures in chlorine dioxide bleaching of kraft pulp has been thoroughly studied. The importance of different structures in the pulp for the occurrence of OCl in bleached pulp and ways to manufacture pulp with a low OCl content bleached in a standard ECF sequence, are dis- cussed. Apart form the obvious fact that a lower charge of chlori- ne dioxide will lead to less chlorination and thus in general lower OCl and AOX and the well-known fact that alkaline extraction Subsequent to chlorination or chlorine dioxide treatment is a very Efficient way of reducing the OCl content of the pulp, new met- Hods are presented.