Reactor performance and microbial community dynamics during aerobic degradation and detoxification of Acid Red B with activated sludge bioaugmented by a yeast Candida tropicalis TL-F1 in MBR

• Azo dye degradation with yeast-bioaugmented MBR was firstly studied.
• Performance of decolorization, TOC removal and detoxification were investigated.
• The bioaugmented MBR achieved high color, TOC and eco-toxicity removals.
• Both of bacterial and fungal communities were analyzed by MiSeq sequencing.
• Candida tropicalis TL-F1 survived and became dominant fungi in the MBR.

A submerged membrane bioreactor (MBR) was constructed to assess the long-term effectiveness of an activated sludge system which was bioaugmented by a yeast Candida tropicalis TL-F1 for degradation and detoxification of Acid Red B (ARB). MiSeq sequencing analysis was performed to analyze the dynamics of microbial community. Results showed that both of decolorization and TOC removal rates were unstable during the non-augmented phase, which were less than 90% and 80%, respectively. By contrast, color and TOC removal percentages after bioaugmentation achieved to more than 96% and 97%, respectively. Furthermore, the bioaugmented system could also tolerate shock loading of ARB and maintain stable and sufficient biomass in the MBR. On the other hand, the eco-toxicity of the effluent with bioaugmentation was much lower than those of influent and the effluent without bioaugmentation. The results of MiSeq sequencing showed that both of bacterial and fungal communities obviously shifted due to bioaugmentation and shock loading. Furthermore, Candida tropicalis TL-F1 survived and became the dominant fungus in the bioaugmented system.