Branqueamento de celulose e o pré-branqueamento enzimático: potencial, benefícios e desafios na redução do uso de produtos químicos

Abstract

This work explores the potential of enzymatic pre-bleaching of pulp as an alternative to reduce the intensive use of chemical products in bleaching processes, aligning with the growing demands for sustainability in the pulp and paper industry. Through a comprehensive literature review, the study analyzes the evolution of bleaching technologies, from methods based on elemental chlorine to ECF (Elemental Chlorine Free) and TCF (Totally Chlorine Free) sequences, contextualizing the introduction of biotechnology as a strategic advancement. The results indicate that pretreatment with enzymes, especially xylanases, promotes a significant reduction in the consumption of chemical reagents, such as chlorine dioxide, in the range of 15% to 25%. This leads to both economic benefits, through savings on inputs, and environmental benefits, through the lower formation of organochlorine compounds (AOX) in the effluents. The mechanism of action of xylanases consists of the hydrolysis of the redeposited xylan layer on the fibers, increasing their porosity and facilitating the removal of residual lignin in the subsequent chemical stages. However, the implementation of the technology presents challenges, such as an increase in the organic load (COD) in the filtrate from the enzymatic stage and a potential process yield loss. It is concluded that enzymatic bleaching is a viable and consolidated technology, whose success depends on a careful balance between economic and environmental gains and operational challenges, requiring a customized analysis for each industrial plant. Continuous innovation in biotechnology is fundamental to optimizing the process and expanding its application, reaffirming its role in the pursuit of a more competitive and sustainable pulp industry.