Responds of Thiosulfate-Driven Autotrophic Denitrifiers to S2−, Fes and Scn− in Autotrophic Denitrification Process: Transformations of Nitrogen and Sulfur

Abstract

For sulfur (−2)-based autotrophic denitrification processes, their start-up was not clear using thiosulfate-driven autotrophic denitrifiers (TAD). The study aimed to investigate the response behaviors of thiosulfate-driven autotrophic denitrifiers to different sulfur (−2) compounds (S2− , FeS, and SCN− ). The results showed that the TAD could respond rapidly to these sulfur (−2) compounds in autotrophic denitrification process, which might be attributed mainly to Thiobacillus genus. The maximum denitrification rate was observed in the presence of SCN− , followed by FeS and S2− . The highest nitrite accumulation (102.7 mg N/L) was observed in FeS system, and the nitrite accumulation rate was up to 88%. However, the reduction of nitrate was significantly inhibited in S2− system during cycle tests. Intermediates containing sulfur (e.g., S0 and S2O32− ) were produced following denitrification using S2− and FeS, but detected rarely in SCN− system. Additionally, the removal of SCN− was limited obviously by S2− or FeS in coexistence system. This finding presented key insights for fast the start-up of sulfur (−2)-based autotrophic denitrification via TAD biomass, regulation of sulfur (−2) species and development of novel combined processes in treatment of wastewaters containing S2− and SCN−.

Keywords: Sulfur (−2) species, Thiosulfate-driven autotrophic denitrifier, Response, Denitrification, Sulfur oxidation