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

ABSTRACT

Nitrate contamination is a risk to human health and may cause eutrophication, whereas H₂S is an undesirable constituent in biogas. In order to better understand denitrification using gaseous H₂S as electron donor, this study investigated denitrification at different molar ratios of sulfur and nitrogen (S/N ratios) and H₂S 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 H₂S 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, Thiobacillus and Sulfurimonas, that were responsible for autotrophic denitrification. The simultaneous removal of nitrate and H₂S using a wide range of concentrations could be achieved.

KEYWORDS:

• Hydrogen sulfide
• denitrification
• S/N ratio
• wastewater
• microbial community

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge financial support from the National Natural Science Foundation of China (NSFC) [grant number 51578519], Major Science and Technology Program for Water Pollution Control and Treatment [grant number 2017ZX07202002] and the Fundamental Research Funds for the Central Universities [grant number 2652017187].