title: In situ probing the effect of potentials on the microenvironment of heterotrophic denitrification biofilm with microelectrodes.
abstract: Bio-electrochemical reactor provides a promising technology to remove nitrogen contaminants in water. In this study, a heterotrophic biofilm for denitrification process was developed, and stable total nitrogen removal efficiencies (>80%) were achieved. Fluorescence in situ hybridization showed that genes norB mainly transcribed in inner biofilm while genes nosZ showed similar transcription activities in the entire biofilm. The microelectrodes of pH and nitrous oxide (N₂O) were applied to profile the microenvironment of denitrification biofilm. In all measurements, the microenvironment pH decreased as a function of biofilm depth. The highest N₂O concentration of 90 μM in biofilm was detected when the bulk solution pH was 7.3, and an applied potential of -0.2V did not decrease the yield of N₂O in biofilm at pH 7.3. Nevertheless, pH 9.5 or an applied potential of -0.4V seemed not to suppress the yield of N₂O in biofilm.
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xiao
authors.forename: Song
authors.initials: S
authors.lastname: Wu
authors.forename: Zhao-Hui
authors.initials: ZH
authors.lastname: Yang
authors.forename: Ze-Jie
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Chang-Zhou
authors.initials: CZ
authors.lastname: Yan
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
mesh_terms: D018441:Biofilms; D019149:Bioreactors; D058440:Denitrification; D006863:Hydrogen-Ion Concentration; D008839:Microelectrodes; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Biofilm; Denitrification; Microelectrode; Microenvironment; Nitrous oxide