Application of enzymes in producing bleached pulp from wheat straw

Area of Science:

• Biotechnology
• Pulp and Paper Industry
• Enzymology

Background:

• Wheat straw pulp production often involves harsh chemical treatments.
• Enzymatic treatments offer a potential eco-friendly alternative for pulp modification.
• Understanding enzyme activity, particularly xylanase and cellulase, is crucial for optimizing pulping.

Purpose of the Study:

• To evaluate the effectiveness of crude enzymes, specifically xylanase, in pre-treating wheat straw pulp.
• To assess the impact of enzymatic pre-treatment on pulp properties such as kappa number, brightness, and strength.
• To investigate the potential of xylanase to replace or supplement traditional chemical pulping stages.

Main Methods:

• Crude enzyme preparations from Penicillium A10 and Aspergillus L22 were used for pre-treatment.
• Enzyme dosages, particularly xylanase at 4 IU/g, were applied prior to pulping.
• Pulp kappa number, brightness (ISO), strength properties (breaking length), post-color number, and beating degree (SR) were measured.
• Enzymatic treatments were compared against a control and evaluated in different pulping sequences (CEH).

Main Results:

• Xylanase pre-treatment decreased the pulp kappa number by 6.29% (Penicillium A10) and 12.07% (Aspergillus L22).
• Enzymatic pre-bleaching reduced chlorine charge by 20-30% and increased brightness by 4-5% ISO.
• Modification of bleached pulp with xylanase (3 IU/g) improved brightness (3-6% ISO) and breaking length (160-790 m).
• High cellulase activity negatively impacted pulping; xylanase showed potential to substitute alkali extraction.

Conclusions:

• Xylanase pre-treatment is effective in reducing kappa number and chemical consumption in wheat straw pulping.
• Enzymatic modification enhances pulp brightness and strength properties.
• Xylanase offers a viable alternative to alkali extraction, contributing to more sustainable pulp production.