|Title||Effect of low concentrations of dissolved oxygen on the activity of denitrifying methanotrophic bacteria|
|Author(s)||Kampman, Christel; Piai, Laura; Temmink, Hardy; Hendrickx, Tim L.G.; Zeeman, Grietje; Buisman, Cees J.N.|
|Source||Water Science and Technology 77 (2018)11. - ISSN 0273-1223 - p. 2589 - 2597.|
|Publication type||Refereed Article in a scientific journal|
|Keyword(s)||Anaerobic methane oxidation - Anaerobic wastewater treatment - Denitrification - Methylomirabilis oxyfera - Oxygen|
Chemical energy can be recovered from municipal wastewater as biogas through anaerobic treatment. However, effluent from direct anaerobic wastewater treatment at low temperatures still contains ammonium and substantial amounts of dissolved CH4. After nitritation, CH4 can be used as electron donor for denitrification by the anaerobic bacterium Candidatus Methylomirabilis oxyfera. The effect of 0.7% (0.35 mg dissolved O2/L), 1.1% (0.49 mg dissolved O2/L), and 2.0% (1.0 mg dissolved O2/L), on denitrifying activity was tested. Results demonstrated that at 0.7% O2, denitrifying methanotrophic activity slightly increased and returned to its original level after O2 had been removed. At 1.1% O2, CH4 consumption rate increased 118%, nitrite consumption rate increased 58%. After removal of O2, CH4 consumption rate fully recovered, and nitrite consumption rate returned to 88%. These indicate that traces of O2 that bacteria are likely to be exposed to in wastewater treatment are not expected to negatively affect the denitrifying methanotrophic process. The presence of 2.0% O2 inhibited denitrifying activity. Nitrite consumption rate decreased 60% and did not recover after removal of O2. No clear effect on CH4 consumption was observed.