Elemental sulfur-based autotrophic denitrification and denitritation: microbially catalyzed sulfur hydrolysis and nitrogen conversions

The hydrolysis of elemental sulfur (S-0) coupled to S-0-based denitrification and denitritation was investigated in batch bioassays by microbiological and modeling approaches. In the denitrification experiments, the highest obtained NO3--N removal rate was 20.9 mg/l.d. In the experiments with the biomass enriched on NO2-, a NO2--N removal rate of 10.7 mg/l.d was achieved even at a NO2--N concentration as high as 240 mg/l. The Helicobacteraceae family was only observed in the biofilm attached onto the chemically-synthesized S-0 particles with a relative abundance up to 37.1%, suggesting it was the hydrolytic biomass capable of S-0 solubilization in the novel surface-based model. S-0-driven denitrification was modeled as a two-step process in order to explicitly account for the sequential reduction of NO3- to NO2- and then to N-2 by denitrifying bacteria. (C) 2018 Elsevier Ltd. All rights reserved.