Characteristics of hydrogenotrophic denitrification in a combined system of gas-permeable membrane and a biofilm reactor

Hydrogenotrophic denitrification of potable water: A review

“…Saturation constants of 0.18 and 0.16 mg N/l were reported for nitrate and nitrite, respectively [8]. The values of nitrate saturation constants determined by Visvanathan et al [22] and Lu et al [106] were 0.0001 and 2.09 mg N/l, respectively. In another study, the reported hydrogen saturation constant ranged from 0.0009 to 0.0066 mg H 2 /l [78].…”

“…Complete denitrification of 16.34 mg NO 3 − -N/l was achieved with a velocity of 0.3 m/d. Lu et al [106] used a tank in which hydrogen was diffused via gas-permeable membrane and water was hydrogenated. Afterwards, the hydrogenated water was introduced in the fixed-bed reactor.…”

“…Many of the reviewed systems have the same H 2 provision scheme (gas sparging) either in a separated hydrogen saturation tank [8,10,106] or directly to the reactor [15,36]. The main limitation of hydrogen-driven denitrification is the low solubility of hydrogen gas resulting in low-mass transfer rate and possible accumulation of hydrogen gas in a closed head space thus creating an explosive environment [28].…”

“…Visvanathan et al [22] also used a Monod equation to describe nitrate and biomass effluent variation of a membrane denitrification system. Finally, a double Monod expression was employed by Lu et al [106] to describe the two-step hydrogenotrophic denitrification process, and the saturation constants of nitrate, nitrite and hydrogen were determined by batch experiments.…”

Chemolithotrophic denitrification in biofilm reactors

“…Direct H 2 supply has been carried out with several solutions in order to improve hydrogen diffusion. Gas-permeable membranes have been widely used in PBR applications resulting in high denitrification performances [38]. Hydrogen gas can be also produced directly inside the bioreactor.…”