Fungal pretreatment of unextracted and pressurized hot water extracted Eucalyptus Grandis wood chips

[摘要] ENGLISH ABSTRACT: Unextracted (control) and PHWe Eucalyptus grandis wood chips were pulped at 15% activealkali (AA) and 1% antraquinone (AQ). Another batch of wood chips were then inoculatedwith fungal co-cultures of Aspergillus flavipes and Pycnoporus sanguineus. FCCi wood chipswere incubated for four weeks; one PHWe inoculated experimental treatment was incubatedfor three weeks. The full pulping cycle (160 min) was used to digest the experimentaltreatments with the exception of one lot of PHWe wood chips that were pulped for 150minutes. A further experimental treatment of PHWe wood chips was cooked at a reduced AAcharge of 14% and 1% AQ. Analysis of variance (ANOVA) of the data from all theexperimental treatments was conducted and the differences within the experimental treatmentswere determined using Statistica (v7, 1984–2006). The F-value (Fischer distribution) and thep-value as well as a non-parametric test known as the Mann-Whitney procedure was tested atthe 95% confidence limit. For a further enhancement of the 95% confidence limit the screenedyield data was tested by the Bootstrap method. Scanning electron micrographs clearlydemonstrated the changed structure and appearance of the chip cross-sectional area after thedifferent pretreatments.Although the mean average results of all the screened pulp yields showed no significantstatistical difference (p> 0.05), differences in screened yield of up to 2.5% were obtained. Allthe weighted means of the rejects showed a significant difference (p < 0.05). Other pulpproperties like shive content, chemical consumption, Kappa number, handsheet brightness andstrength tests showed mixed results i.e. rejected or accepted the hypothesis (p> or =or < 0.05).The hypothesis that the combined PHWE and FCCI of wood chips would further increase thepulp yield had to be rejected. It is however anticipated that the combination of PHWE withsuccessive co-culture fungal pretreatment would be very beneficial in obtaining higher pulpyields for fully bleached chemical pulp. Further research would be required to test thisassumption. This investigation confirmed the expected beneficial effects of combined PHWEand FCCI pretreatments of wood chips on the strength properties. In addition the combinedtreatment also improved the initial bonding strength potential of the unbeaten fibres.

[发布机构] Stellenbosch University