“…As a promising alternative of heterotrophic denitrication, autotrophic denitrication, using inorganic compounds including hydrogen gas, ferrous iron and reduced sulfur compounds as electron donor, is increasingly being studied in recent years. [17][18][19][20][21][22][23] Autotrophic denitrication especially hydrogen-based one (hydrogenotrophic denitrication) is desirable because of its nontoxicity and low biomass. 24 During the hydrogenotrophic denitrication process, hydrogen is used by hydrogenotrophic denitrifying bacteria as electron donor, and inorganic carbon, such as carbon dioxide and bicarbonate, is used as carbon source.…”