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Environ Sci Technol

Title:		Activated carbon as an electron acceptor and redox mediator during the anaerobic biotransformation of azo dyes
Author(s):		van der Zee FP; Bisschops IA; Lettinga G; Field JA;
Address:		"Agrotechnology and Food Sciences, Subdepartment of Environmental Technology, Wageningen University, P.O. Box 8129, 6700 EV, Wageningen, The Netherlands. frankvdz@iq.uva.es"
Journal Title:		Environ Sci Technol
Year:		2003
Volume:		37
Issue:		2
Page Number:		402 - 408
DOI:		10.1021/es025885o
ISSN/ISBN:		0013-936X (Print) 0013-936X (Linking)
Abstract:		"Activated carbon (AC) has a long history of applications in environmental technology as an adsorbent of pollutants for the purification of drinking waters and wastewaters. Here we describe novel role of AC as redox mediator in accelerating the reductive transformation of pollutants as well as a terminal electron acceptor in the biological oxidation of an organic substrate. This study explores the use of AC as an immobilized redox mediator for the reduction of a recalcitrant azo dye (hydrolyzed Reactive Red 2) in laboratory-scale anaerobic bioreactors, using volatile fatty acids as electron donor. The incorporation of AC in the sludge bed greatly improved dye removal and formation of aniline, a dye reduction product. These results indicate that AC acts as a redox mediator. In supporting batch experiments, bacteria were shown to oxidize acetate at the expense of reducing AC. Furthermore, AC greatly accelerated the chemical reduction of an azo dye by sulfide. The results taken as a whole clearly suggest that AC accepts electrons from the microbial oxidation of organic acids and transfers the electrons to azo dyes, accelerating their reduction. A possible role of quinone surface groups in the catalysis is discussed"
Keywords:		"Adsorption Azo Compounds/*metabolism Biotransformation Carbon/*chemistry Catalysis Coloring Agents/*metabolism Electrons Oxidation-Reduction Waste Disposal, Fluid Water Pollutants, Chemical/*metabolism Water Purification/*methods;"
Notes:		"Medlinevan der Zee, Frank P Bisschops, Iemke A E Lettinga, Gatze Field, Jim A eng Research Support, Non-U.S. Gov't 2003/02/05 Environ Sci Technol. 2003 Jan 15; 37(2):402-8. doi: 10.1021/es025885o"