Biodegradation of selected azo dyes under methanogenic conditions

Biological treatment of wastewaters discharged by the textile industry could potentially be problematic due to the high toxicity and recalcitrance of the commonly-used azo dye compounds. In the present report, the fate of two azo dyes under methanogenic conditions was studied. Mordant Orange 1 (MO1)...

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Bibliographic Details
Published in:Water science and technology 1997, Vol.36 (6-7), p.65-72
Main Authors: Razo-Flores, Elías, Luijten, Maurice, Donlon, Brian, Lettinga, Gatze, Field, Jim
Format: Article
Language:English
Subjects:
Adaptation
Anaerobic bacteria
Anaerobic degradation
Anaerobic digestion
Azo dyes
Azodisalicylate
Bacteria
Biodegradation
Biological treatment
Bioreactors
Decoloring
Dyes
Granular sludge
Metabolism
Methanogenic conditions
Methanogens
Mineralization
Mordant Orange 1
Phenylenediamine
Reactors
Reduction
Textile industry
Toxicity
Trace levels
UASB reactor
Upflow anaerobic sludge blanket reactors
Wastewater treatment
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Summary:Biological treatment of wastewaters discharged by the textile industry could potentially be problematic due to the high toxicity and recalcitrance of the commonly-used azo dye compounds. In the present report, the fate of two azo dyes under methanogenic conditions was studied. Mordant Orange 1 (MO1) and Azodisalicylate (ADS) were completely reduced and decolorised in continuous UASB reactors in the presence of cosubstrates. In the MO1 reactor, both 5-aminosalicylic acid (5-ASA) and 1,4-phenylenediamine were identified as products of azo cleavage. After long adaptation periods, 5-ASA was detected at trace levels, indicating further mineralization. ADS, a pharmaceutical azo dye constructed from two 5-ASA units, was completely mineralized even in the absence of cosubstrate, indicating that the metabolism of 5-ASA could provide the reducing equivalents needed for the azo reduction. Batch experiments confirmed the ADS mineralization. These results demonstrate that some azo dyes could serve as a carbon, energy, and nitrogen source for anaerobic bacteria.
ISSN:0273-1223
1996-9732
DOI:10.1016/S0273-1223(97)00508-8