Characterization of functional microbial communities involved in different transformation stages in a full-scale printing and dyeing wastewater treatment plant

Abstract

A simplified model employing anaerobic3-oxic2-sedimentaion reactor and multiple linear regression was proposed in this study. Four typical azo dyes were treated as model contaminants. Decolorization firstly happened by the cleavage of NN double bond, aromatic amines were yielded. Afterwards, deamination and desulphurization occurred, phenol and naphthol were formed. Then dearomatization reactions were detected by introducing the atoms of O2 into the aromatic nucleus. At last complete mineralization happened, yielding CO2 and H2O. Two types of functional microbial communities for NN double bond cleavage and aromatic rings broken were statistically identified with multiple linear regression and the results were presented in t-value biplots. The genera of Enterococcus, Acidaminococcus, Bacteroides, Megasphaera and Klebsiella played significantly important roles in cleavage of NN, while Pseudomonas, Anaerovorax and Longilinea demonstrated significantly positive relationship with breaking the aromatic rings. We must point out that species in the genera of Anaerovorax and Longilinea are usually reported as strictly anaerobic bacteria, while, in our study, they were abundant in aerobic compartments and significantly positive with aromatic compounds. The findings will provide important information for operation process optimization and treatment efficiency improvement in printing and dyeing wastewater treatment plant.