Continuously Biodegrading High Concentration of Acid Red B Under Hypersaline Conditions in a Membrane Bioreactor Bioaugmented by a Halotolerant Yeast Pichia occidentalis G1 and Microbial Community Dynamics

摘要

Effluents from textile and dyeing industries are typical hypersaline wastewaters, which also contain high concentration of dyes (most are azo types). To achieve effective and environment-friendly treatment, a laboratory-scale activated sludge-based membrane bioreactor (MBR), which was bioaugmented by a halotolerant yeast Pichia occidentalis G1, was constructed and assessed through a long-term operation. Dynamics of microbial community during the operation were analyzed by high-throughput sequencing method. The results demonstrated that the bioaugmented MBR was more stable and efficient for decolorization, chemical oxygen demand removal, and detoxification, as well as stronger tolerance to shock loading than the nonaugmented control. Sludge concentration in the yeast-augmented MBR was also higher than the other two controls, which might ensure its more stable and higher treatment efficiency. MiSeq sequencing results suggested that the most abundant fungal genus in the bioaugmented MBR were identified as Pichia, indicating the possibly successful colonization of strain G1 or some other species belonging to the same genus with high metabolic activity. Fungal species belonging to Candida were also enriched with bioaugmentation. Rhodanobacter was the most dominant bacterial genera in the bioaugmented system, which might share acidic conditions with fungi belonging to Pichia. This method was potentially effective in bioremediation of hypersaline industrial wastewaters, which contained azo dyes.