ADSORPTION OF LIPASE ON PULP FIBERS DURING BIOLOGICAL PITCH CONTROL IN PAPER-INDUSTRY

Biological pitch control is one of the new methods for reducing pitch deposits on paper machines by hydrolysing the triglycerides in the resins and washing out the free fatty acids with sodium hydroxide solution. This method consists of adding lipase to the pulp and incubating the resulting mixture for 3 h. The question whether the lipase molecules are adsorbed onto the fibers or on the resin particles or whether they can be recycled from the supernatant and reused for this purpose is of utmost interest for this process. We found that lipase was highly adsorbed onto the fibers. Therefore it is possible to add the enzyme at preferably low pulp consistencies and to increase the consistency afterwards, thus increasing the concentration of the enzyme in the system.