Operation performance and microbial community of sulfur-based autotrophic denitrification sludge with different sulfur sources.

Operation performance and bacterial community structure of sulfur-based autotrophic denitrification (SAD) based on different sulfur sources served as electron donor was first parallelly compared among three sequencing batch reactors. Sulfur and sodium thiosulfate systems achieved similar operation performance and were superior to that of sodium sulfide. When the influent NO3--N concentration ranged from 50 to 150 mg/L, the effluent NO3--N concentrations of the sulfur and sodium thiosulfate systems were 0-5.99 mg/L and 0-4.52 mg/L, respectively, without NO2--N accumulation. However, when the effluent concentration of NO3--N in the sodium sulfide system was 0-10.38 mg/L, that of NO2--N in the effluent was 0-39.85 mg/L. In addition, participation of sulfur sources presented obvious pressure on the bacterial community structure based on the high-throughput sequencing. Microbial diversity results indicated that sludge with elemental sulfur as electron donor had the richest microbial diversity, followed by sodium thiosulfate and sodium sulfide. Moreover, sludge with elemental sulfur and sodium thiosulfate as electron donor demonstrated more similar community structure compared with the sludge that denitrified with sodium sulfide according to the microbial similarity analysis. The 9.34%, 24.3% and 29.6% of sequences could be assigned to potential SAD organisms from sludge denitrifying with elemental sulfur, sodium thiosulfate and sodium sulfide, respectively. Furthermore, all sludge denitrifying with different sulfur sources showed an enrichment of separate core functional microorganisms. This study could provide an insight into improving the understanding of SAD in engineering applications.