The analysis of handsheets from wheat straw following solid substrate fermentation by Streptomyces cyaneus and soda cooking treatment

The recent interest in the utilisation of agricultural fibres has promoted research into their potential as raw materials for the pulp and paper industry. In the current study, we report on the effect of biological pretreatment of wheat straw by Streptomyces cyaneus on the performance of the handsheets produced from the treated pulps. The pre-treatment of wheat straw with S. cyaneus had a positive effect on both the burst and tear indexes of the pulps but had a negative impact on tensile index. No significant variation in permeability and in folding endurance was observed. Manipulation of handsheets from wheat straw through biological treatment may therefore result in improved quality traits.

TCF bleaching of wheat straw pulp using ozone and xylanase. Part B: kinetic studies

The reaction kinetics of ozone bleaching of wheat straw pulp has been studied for the first time. The results were compared with eucalyptus pulp in order to know that both raw materials have a similar behaviour. Ozone treatments were carried out in a special reactor at low consistency (0.5% o.d.p.). The main variables were consumption of ozone by the pulp and application of a xylanase treatment (X) prior to the oxygen stage (O). The responses measured were kappa number, viscosity and brightness, to give the kinetic expressions for delignification, cellulose degradation and elimination of chromophore groups, along with calculation of selectivity. Cellulose degradation and elimination of lignin and chromophore groups show first-order kinetics in all cases. The kinetics of the enzyme pre-treatment effect shows similar behaviour in both raw materials, although the constants of delignification and elimination of chromophore are higher in straw pulp.

TCF bleaching of wheat straw pulp using ozone and xylanase. Part A: paper quality assessment

The XOAZRP TCF sequence was applied to bleach wheat straw pulp. Following each bleaching stage, the properties of the pulp (viz. kappa number, standard viscosity, borohydride viscosity and brightness) and of the resulting effluents were determined. The performance of the reagents was analyzed through the studies of xylanase treatment and crystallinity and scanning electron microscopy of the pulps. Finally, the pulp was refined at 1000 revolutions in a PFI mill and the mechanical properties of the resulting paper were determined and compared with those of paper from a eucalyptus pulp. Despite its shortcomings, wheat straw pulp can be effectively bleached with the proposed TCF sequence.