Effect of Fungal Degradation of Wood Chips on Pulp and Paper Properties at Panafrican Paper Mills, Webuye, Kenya

Abstract

Losses caused by wood decay fungi in a Pinus patula chip pile in storage were studied for six months at Panafrican Paper Mills, Webuye, Kenya. The losses were quantified in terms of pulp yield, pulp quality, and paper properties. Light microscopy and scanning electron microscope observations confirmed that soft rot, white rot and brown rot caused fungal decay in the pile. Tests on pulp quality showed that severe fungal attack at 1m height reduced fibre length to less than 2.0 mm compared to 3.8 mm for the control at both 1m and 4m height. Pulp yield loss of up to 12.0% was recorded amounting to about 40 ha of pulpwood going to waste per year. Statistical comparisons using the Duncan’s Multiple Range Test indicated that strength values for paper specimens from the degraded chips were significantly lower than that of the control. Paper strength properties decreased substantially within six months with the tensile, tear and burst strengths decreasing by almost 17%, 19.0% and 14.0% respectively. Results indicate that the storage of pulpwood in multiple piles to reduce pile height and reduction in storage time to less than one month coupled with processing of chips on a “first in first out basis” can minimize the amount of degradation. They may be used as a basis for formulating control measures to minimize degradation at different chip heights. It is recommended that the firm adopt these storage practices, install porous material under each pile and construct drainage system to avoid retention of rainwater underneath the piles.