The Fate of14C-Labelled High Molecular Weight Chlorinated Lignin and Chromophoric Material During Microbial Treatment of Bleached Kraft Effluent

Abstract
Bleached kraft effluent (BKE) is highly coloured due to the presence of high molecular weight, chlorinated, oxidised lignin. The dimethyl formamide-soluble portion of BKE was radiolabelled by methoxylation with 14C-methyl iodide, and the resulting product (C14-BKE) was used to Investigate the mechanism of colour removal by fungi and bacteria. The white-rot fungi Coriolus versicolor and Pleurotus sajor-caju decolorised the solutions, and depolymerised the C14-BKE. Both fungi produced about 16Z 14CO2 from C14-BKE In 20 days. The three bacteria tested, Bacillus cereus and two strains of Pseudomonas aeruginosa, removed colour primarily by adsorption with little depolymerisation or mineralization. The adsorbed C14-BKE could be removed from bacterial cells by washing with 0.1 M NaOH.