Microbial diversity in a continuous system based on rice husks for biodegradation of the azo dyes Reactive Red 2 and Reactive Black 5

► Efficient degradation of two azo dyes by a cost-effective continuous process. ► Microorganisms analyzed by PCR, DGGE and identified by 16S rRNA sequencing. ► Several interesting species identified some known to produce azoreductase. ► Robust degradation performance over 80%, without any operational interruptions. ► Degradation monitored by LC/MS, no metabolites detected in the treated water.