COMPLETE BIODEGRADATION OF THE AZO-DYE AZODISALICYLATE UNDER ANAEROBIC CONDITIONS

Citation
E. Razoflores et al., COMPLETE BIODEGRADATION OF THE AZO-DYE AZODISALICYLATE UNDER ANAEROBIC CONDITIONS, Environmental science & technology, 31(7), 1997, pp. 2098-2103
Citations number
38
Categorie Soggetti
Environmental Sciences","Engineering, Environmental
ISSN journal
0013936X
Volume
31
Issue
7
Year of publication
1997
Pages
2098 - 2103
Database
ISI
SICI code
0013-936X(1997)31:7<2098:CBOTAA>2.0.ZU;2-V
Abstract
Azo dyes are a widespread class of poorly biodegradable industrial pol lutants. In anaerobic environments, azo bonds are reductively cleaved yielding carcinogenic aromatic amines, many of which are assumed to re sist further metabolism by anaerobes. Here we report for the first tim e that an azo dye compound is completely biodegradable in the absence of oxygen. A pharmaceutical azo dye, azo-disalicylate, constructed fro m two 5-aminosalicylic acid (5ASA) molecules was mineralized in an ada pted methanogenic consortium to CH4 and NH3 with transient accumulatio n of 5ASA as a degradation intermediate in both batch assays and conti nuous bioreactors. The anaerobic metabolism of 5ASA was shown to provi de the electrons required for the initial reductive cleavage of the az o group. Our results suggest that it is possible to design azo dyes th at are fully mineralized in the environment; thereby, avoiding accumul ation of notorious toxic intermediates.