ABSTRACT
RAGASSE is an agricultural by product from sugar cane after the cane is harvested and crushed to extract the juice. The utilization of bagasse as raw material for pulp and paper industry is increasing rapidly which also increasing pollution to the environment. In renewable resource to reduce chemical pollution, white rot fungi or lignin-degrading fungi was employed to contribute to remove lignin from raw materials. The aim of this investigation, is to determine the activity of white-rot fungi on bagasse as in in vivo biopulping or pre-treatment by comparing the lignin content of bagasse before and after the biodegradation in different conditions. It was found that the most favorable conditions for bagasse pulping can be achieved by treatment with propylene glycol [PG] 90% under pressure for 1 h or without pressure for 2 h at the cooking temperature 150°C. The mentioned treatments gave high pulp yield, with no rejects and low kappa number. The extractive removal of bagasse [10 mesh] by steam resulted to high weight loss, acid perceptible polymeric lignin [APPL] production and low kappa number. The biological 4 weeks treatment of bagasse by Ophiostoma piliferum at 27°C increased the brightness, breaking length and tear factor of unbleached bagasse paper sheets. when compared with steam treatment. Using mixed culture of Ceriporiopsis subvermispora and O. piliferum either from one or two-stage cultures for extractive removal and biodegradation of bagasse, led to the improvement the chemical pulp composition and the properties of unbleached paper sheets. One stage culture treatment increased the unbleached paper sheets properties which expressed as brightness, breaking length and tear factor by 5.6%. 0.08 km and 3.78, compared with the two-stage culture treatment results, which were 3.08%, 21.41 km and 3.69, respectively . The mentioned results were more convenient when compared with steam extraction method. Scanning electron micrographs [SEM] revealed that the biological fibers of the produced paper sheets exhibit a cleaner surface, high flexibility and conformability, which would be contributed to the good bonding nature
ABSTRACT
FUNGAL xylanase and lignin peroxidase enzymes were used as pretreatment for biobleaching of bagasse biopulping treated with mixed culture of Ophiostoma piliferum and Ceriporiopsis subvermispora SS- 33 at 27°C for one week in MV medium as static culture before the pulping with propylene glycol [PG]. Some agricultural wastes such as corn cobs, wheat bran and bagasse powder were used as a sole carbon source for xylanase production. The maximum production of fungal xylanase was attained after 7 days- fermentation period on corn cobs medium at 30°C on rotary shake flasks at 150 rpm. The enzyme production by Trichoderma reesie NRRL 6156 increased 1.17 fold as compared with that obtained by Trichoderma viride NRRL 13034.Using 10.30 IU xylanase/g bagasse biopulp, produced by Trtchoderma reesie NRRL 6156, for 4 h at 50°C was the best xylanase pretreatment which reduced klason lignin% and increased the brightness % of bagasse biopulp. The solid-state HC-LN medium supplemented with tween 60 and veratryl alcohol in addition to 10 grams of bagasse pulp was the best one for lignin peroxidase production by Phanerochaete chrvsosporium NRRL 6361, the enzyme activity of this treatment [77.75 IU/L] was higher than that obtained using semi-solid [47.75 IU/L] and liquid [36.50 IU/L] state, after 6 days incubation period. The optimum lignin peroxidase dose, for the best biobleaching of unbleached bagasse biopulp at 37°C for 8 h was 1.54 lU/g. Using these enzyme pretreatments led to increase the brightness %, breaking length and tear factor 6.7, 18.89 and 12.7 % by xylanase bleached bagasse [XBB] and 8.94 %, 34.92 and 30.82 %, by lignin peroxidase bleached bagasse [LBB], respectively. The enzyme treatment of LBB and XBB led to decrease of chlorine consumption 40% and 26.67 % as compared to control. Scanning electron microscope [SEM] of bleached bagasse pulp clearly showed fiber that exposed to enzymes treatment had a more open surface and it becomes more accessible to subsequent bleaching agents. The biologicaly pretreatment of bagasse pulp with xylanase orlignin peroxidase enzymes led to increase in the crystallinty by 11.29 and 8.3 %, respectively