Enzymatic Bioremediation of Effluent from Sugarcane Bagasse Soda Delignification Process

This work aims to evaluate the recovery of soluble lignin from an effluent produced in the alkaline delignification of sugarcane bagasse. The lignin polymerization was carried out using different substract-enzyme relation, namely 0.05 and 1.8 mg soluble lignin for peroxidase activity, and different H2O2 concentration, namely 0.18 and 2.1 mol of H2O2 per peroxidase unit, furthermore was achieved using horseradish peroxidase and a preliminary study using laccase produced by Trametes versicolor. The highest lignin polymerization yield was 93 % for 50 Mg lignin/unit of peroxidase activity and 0.2 Mmol of H2O2/unit of peroxidase activity. The polymerization process occurred after a considerable increase in the molecular weight of lignin (from 415 Da in the effluent to 2,122 Da in the polymer obtained after 30 min of reaction) as demonstrated by gel permeation chromatography. The average molecular weight of the obtained polymer changed as a function of reaction time, which of 0, 0.5, 4.0, 8.0, 16.0 and 42.0 h produced lignin polymers with 415, 2,122, 1,576, 1,150, 794 and 4,595 Da, respectively. The preliminary treatment study of the effluent with a culture broth of T. versicolor with laccase increased the average molecular weight of soluble lignin from 415 to 1,150 Da, however the polymerization catalyzed by laccase was not accomplished by the effective lignin polymerization followed by an efficient separation.