The performance and microbial community profiles in a sequencing batch reactor(SBR) treating saline wastewater were studied over 300 days from 0% to 2.0% salinity. The effects of crystal violet wastewater and nano-ferroferric oxide on microbial communities were also researched. The experimental results indicated that the activated sludge had high sensitivity to salinity variations in terms of pollutants removal and sedimentation. At 2.0% salinity, the system retained a good performance, and 80% removal rate of COD and 75% removal rate of NH4+-N could be achieved and SVI value was less than 35 mL·g-1; With the increase of salinity, the microbial diversity reduced gradually, the advantageous position of Gram-negative bacteria was gradually replaced by fungi and actinomycetes, whereas Gram-positive bacteria strains remained the advantageous group; In the comparison of activated sludge added with crystal violet dye with the activated sludge samples with a salinity of 2%, it was found that the contents of Parvibaculum and Winogradskyella were higher while the contents of Rhodanobacter and Agrobacterium decreased. In the comparison of crystal violet-activated sludge with and without addition of MNPs, it was found that the contents of Acidocella and Rhodanobacter were higher while the contents of Parvibaculum and Agrobacterium decreased.
Keywords: activated sludge; dye wastewater; microbial community; salinity; sludge volume index(SVI).