In secondary fibre processing several problems are caused by fines,
which are present in high concentrations in recycled pulp. One of the
major problems is the decreased drainage rate, which results in a
reduction of the capacity of paper machines. With enzymatic treatment
the short cellulose fibres can be degraded and drainage properties of
the pulp can be improved.
The aim of this study was to prepare the investigation of the influence
of enzymatic treatment; the results of hydrolysis by cellulases are not
shown here. The freeness (characterised by Schopper-Riegler number) of
reference pulps showed great fluctuation in the parallel experiments,
as this was quantified by variance components analysis. All of
individual steps of the procedure were carefully examined and the
method was standardised based on analysis using an Ishikawa diagram.
The reproducibility and repeatability improved significantly. The
required number of future replicated and repeated experiments in
enzymatic treatments were calculated derived from estimated variance
components of the improved process on untreated pulps.