Mixed culture hydrogenotrophic nitrate reduction in drinking water

Abstract

Isolation and identification of the bacteria from a hydrogenotrophic reactor for the denitrification of drinking water revealed that several microorganisms are involved. Acinetobacter sp., Aeromonas sp., Pseudomonas sp. and Shewanella putrefaciens were repeatedly isolated from the hydrogenotrophic sludge and postulated to be of primary importance in the process. Nitrate reduction to nitrite appears to be a property of a diverse group of organisms. Nitrite reduction was found to be stimulated by the presence of organic growth factors. Thus, in a mixed culture, hydrogenotrophic denitrification reactor, NO inf2 (sup-) formed by NO inf3 (sup-) -reducers can be converted by true denitrifiers thriving on organic growth factors either present in the raw water, or excreted by the microbial community. Mixotrophic growth also contributes to NO inf2 (sup-) reduction. Finally, chemolithotrophic bacteria participate in the nitrite to nitrogen gas conversion.

Hydrogenotrophic denitrification of potable water: A review

“…Pseudomonas stutzeri [79], were observed in many reactors where hydrogen gas was used to stimulate denitrification. Bacteria belonging to the genera Acinetobacter [11,83] have also been reported as dominating members in hydrogen-oxidizing microbial cultures. Members of Acinetobacter sp.…”

“…More specifically, bacteria belonging to the genera Pseudomonas [11,40], e.g. Pseudomonas stutzeri [79], were observed in many reactors where hydrogen gas was used to stimulate denitrification.…”

“…Thus, Paracoccus denitrificans that belongs tos ubclass of Proteobacteria is one of the most intensively studied denitrifying microorganisms [11,[77][78][79]. Populations of Proteobacteria [80,81] and especially ofˇ-Proteobacteria [28,81], such as Thauera sp.…”

“…In addition, the growth rate of autotrophic denitrifying bacteria ensures low biomass build-up and limited operating problems. Thus, hydrogenotrophic bacteria have been successfully used for drinking water nitrate elimination to acceptable levels either in pure [4][5][6][7] or in mixed-cultures [8][9][10][11][12][13][14][15].…”

Kinetics of hydrogen‐dependent denitrification under varying pH and temperature conditions

“…There have been a variety of studies characterizing the microbial ecology in hydrogenotrophic denitrification (Liessens et al, 1992;Selenka and Dressler, 1990;Szekeres et al, 2002;Vanbrabant et al, 1993). In these studies, bacterial populations were isolated from hydrogenotrophic fixed-film systems treating nitrate-contaminated water.…”