Microbial Degradation of Acid Orange and Reactive Black in Presence of Anaerobic Granular Sludge

Abstract

This study mainly focuses on the biodegradation of two azo dyes, Acid Orange and Reactive Black, was evaluated in batch experiments where anaerobic and aerobic conditions were integrated by exposing anaerobic granular sludge to oxygen. Under these conditions, the azo dyes were reduced, resulting in a temporal accumulation of aromatic amines. Subsequently, aniline was degraded further in the presence of oxygen by the facultative aerobic bacteria present in the anaerobic granular sludge. Acid Orange and Reactive Black were also degraded, if inoculum from aerobic enrichment cultures were added to the batch experiments. Due to rapid autoxidation of Acid Orange, no enrichment culture could be established for this compound. The results of this study indicate that aerobic enrichment cultures developed on aromatic amines combined with oxygen tolerant anaerobic granular sludge can potentially be used to completely biodegrade azo dyes under integrated anaerobic/aerobic conditions.