Simultaneous removal of nitrate and hydrogen sulfide by autotrophic denitrification in nitrate-contaminated water treatment.

Nitrate contamination is a risk to human health and may cause eutrophication, whereas HS is an undesirable constituent in biogas. In order to better understand denitrification using gaseous HS as electron donor, this study investigated denitrification at different molar ratios of sulfur and nitrogen (S/N ratios) and HS dosages. Although nitrate continued to decrease, a lag in sulfate generation was observed, implying the generation of sulfide oxidizing intermediates, which accumulated even though nitrate was in excess at lower S/N ratios of 0.19 and 0.38. More addition of HS could result in a longer lag of sulfate generation. Before depletion of dissolved sulfide, denitrification could proceed with little nitrite accumulation. High throughout sequencing analysis identified two major genera, and , that were responsible for autotrophic denitrification. The simultaneous removal of nitrate and HS using a wide range of concentrations could be achieved.