Application of magnetic OMS-2 in sequencing batch reactor for treating dye wastewater as a modulator of microbial community.

The potential and mechanism of synthesized magnetic octahedral molecular sieve (FeO@OMS-2) nanoparticles in enhancing the aerobic microbial ability of sequencing batch reactor (SBR) for treating dye wastewater have been revealed in this study. The addition of FeO@OMS-2 of 0.25g/L enhanced the decolorization of SBRs with an operation cycle of 24h by more than 20%. The 16S rRNA gene high-throughput sequencing indicated FeO@OMS-2 increased the microbial richness and diversity of SBRs, and more importantly, promoted the potential dye-degrading bacteria. After a series of enriching and screening, four bacterial strains with the considerable decolorizing ability were isolated from SBRs, designating Alcaligenes faecalis FP-G1, Bacillus aryabhattai FP-F1, Escherichia fergusonii FP-D1 and Rhodococcus ruber FP-E1, respectively. The growth and decolorization of these pure strains were promoted in the presence of FeO@OMS-2, which agrees with the result of high-throughput sequencing. Monitoring dissolved Fe/Mn ions and investigating the change of oxidation states of Fe/Mn species discovered OMS-2 composition played the critical role in modulating the microbial community. The significant enhancement of Mn-oxidizing/-reducing bacteria suggested microbial Mn redox may be the key action mechanism of FeO@OMS-2, which can provide numerous benefits for the microbial community and decolorization of SBRs.