BIOBLEACHING PROCEDURES FOR PULP FROM AGRICULTURAL RESIDUES USING PHANEROCHAETE-CHRYSOSPORIUM AND ENZYMES

Pulps from agricultural residues (wheat straw) bleached using the DE(P )D sequence (chlorine dioxide-soda plus hydrogen peroxide extraction-c hlorine dioxide) and the FDE(P)D, XDE(P)D and XFDE(P)D sequences, whic h included pretreatment with the fungus Phanerochaete chrysosporium (F ), the enzyme Cartazyme HS (X) and the enzyme plus the fungus (XF) are compared in terms of kappa index, brightness and yield, in addition t o the breaking length, burst index and tear index of paper sheets manu factured from them. XDE(P)D was found to be the best alternative to th e DE(P)D sequence as it surpassed the latter in pulp brightness (by 3. 7%), featured a moderate yield loss (9.3%) and provided paper sheets w ith acceptably smaller breaking length and burst index (20.2 and 13.1% less, respectively). The FDE(P)D sequence was that resulting in the g reatest increase in pulp brightness (8.6%) and the greatest savings in chlorine (10.9%), however, the yield and the breaking length and burs t index of the sheets were markedly decreased (by 25.2, 24.7 and 41.8% , respectively) and the treatment time was rather long. Finally, the X FDE(P)D sequence provided pulp in a considerably diminished yield (34. 5%) and paper sheets with poor properties and essentially the same bri ghtness; this sequence also took a long time to implement. (C) 1997 El sevier Science Ltd.