Browsing by Author "Dyantyi, S. D. (Simphiwe David)"

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    Fungal pretreatment of unextracted and pressurized hot water extracted Eucalyptus Grandis wood chips
    (Stellenbosch : Stellenbosch University, 2007-12) Dyantyi, S. D. (Simphiwe David); Gerischer, G. R. F.; Botha, Alfred; Stellenbosch University. Faculty of Agrisciences. Dept. of Forest and Wood Science.
    ENGLISH ABSTRACT: Unextracted (control) and PHWe Eucalyptus grandis wood chips were pulped at 15% active alkali (AA) and 1% antraquinone (AQ). Another batch of wood chips were then inoculated with fungal co-cultures of Aspergillus flavipes and Pycnoporus sanguineus. FCCi wood chips were incubated for four weeks; one PHWe inoculated experimental treatment was incubated for three weeks. The full pulping cycle (160 min) was used to digest the experimental treatments with the exception of one lot of PHWe wood chips that were pulped for 150 minutes. A further experimental treatment of PHWe wood chips was cooked at a reduced AA charge of 14% and 1% AQ. Analysis of variance (ANOVA) of the data from all the experimental treatments was conducted and the differences within the experimental treatments were determined using Statistica (v7, 1984–2006). The F-value (Fischer distribution) and the p-value as well as a non-parametric test known as the Mann-Whitney procedure was tested at the 95% confidence limit. For a further enhancement of the 95% confidence limit the screened yield data was tested by the Bootstrap method. Scanning electron micrographs clearly demonstrated the changed structure and appearance of the chip cross-sectional area after the different pretreatments. Although the mean average results of all the screened pulp yields showed no significant statistical difference (p> 0.05), differences in screened yield of up to 2.5% were obtained. All the weighted means of the rejects showed a significant difference (p < 0.05). Other pulp properties like shive content, chemical consumption, Kappa number, handsheet brightness and strength 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 the pulp yield had to be rejected. It is however anticipated that the combination of PHWE with successive co-culture fungal pretreatment would be very beneficial in obtaining higher pulp yields for fully bleached chemical pulp. Further research would be required to test this assumption. This investigation confirmed the expected beneficial effects of combined PHWE and FCCI pretreatments of wood chips on the strength properties. In addition the combined treatment also improved the initial bonding strength potential of the unbeaten fibres.