Lesson 2: Biochemical Processes

The pulp making process used by the North Western Pulp and Power Company was state-of-the-art for its day. In this process, two Kamyr continuous digesters, the first in North America, cooked wood chips in a solution of sodium hydroxide and sodium sulphide. These chemicals dissolved most of the lignin (the adhesive material which binds wood fibres together) in the wood but left the cellulose strands intact. The long, strong cellulose fibres were then bleached using a series of chlorine baths. The bleached cellulose was then pressed into bales and sold to papermakers.

Pulp mills discharge significant amounts of water into rivers. The quality of this water became a major environmental concern during the 1980s. The elemental chlorine used in the bleaching process included trace amounts of highly toxic chemicals, for example, dioxins and furans, which were being discharged into the river.