A 10-day mill trial of near-neutral sulphite deinking. Part III: Mill assessment

In this third part of a three-part series on a 10-day mill trial of near-neutral sulphite deinking, we report data collected from outside the recycle plant. The following observations were made: There was better runnability on paper machine #5 which correlated with a lower deposition rate index as measured on the paper machine rich white water. During the entire trial, paper machine #5 ran with 34% DIP. This extended production at 34% DIP with exceptional runnability was unprecedented on PM5. Slightly lower (1-3%) paper-to-paper coefficients of friction of the newsprint paper containing various percentages of sulphite DIP were measured. However, customer feedback was monitored and no negative feedback was obtained. Accelerated concrete corrosion from the news train due to sulphite deinking is unlikely, provided the clarifiers do not become septic. No significant increase in microbiological activity was noted in the recycle furnish. At the end of the trial, the results indicated a healthy, stable activated sludge biomass, with no reason to predict changes in the biotreatment effluent plant operation.