Open AccessRegulating factors of denitrification in trickling filter biofilms as measured with the oxygen/nitrous oxide microsensor
Author(s) -
Dalsgaard Tage,
Revsbech Niels Peter
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05771.x
Subject(s) - denitrification , denitrifying bacteria , anoxic waters , biofilm , environmental chemistry , trickling filter , nitrous oxide , chemistry , aerobic denitrification , organic matter , environmental engineering , nitrogen , biology , environmental science , bacteria , organic chemistry , wastewater , genetics
Microzonation of denitrification in trickling filter biofilms was studied using a combined microsensor for O 2 and N 2 O. Denitrification was measured as a function of concentrations of O 2 , NO 3 − , organic matter and NH 4 + and was found to occur only in part of the biofilm. At increased concentrations of NO 3 − the thickness of the denitrifying zone increased and thereby increased the total denitrification whereas addition of dissolved organic matter increased the rates of denitrification within the denitrifying part of the biofilm, expressed per volume biofilm. The presence of NH 4 + decreased the rate of NO 3 − assimilation and thereby increased the availability of NO 3 − for denitrification. Denitrification was only found at O 2 concentrations below approximately 20 μM. The toxic zone normally extended 0.2–0.3 mm below the biofilm surface, but when the biofilm was exposed to light photosynthetically produced O 2 pushed the oxic‐anoxic interface down to 1.3 mm. Denitrification stopped when O 2 was introduced to the denitrifying zone, but even after exposure to O 2 for 18 h denitrification began immediately after returning to anoxic conditions. Steady state in denitrification was then reached in only 30 min and the rate found then was identical to the rate before exposure to O 2 , as well as the rate 15 h after return to anoxia. The immediate onset of denitrification suggest that most of the denitrifiers in the biofilm possessed constitutive enzyme systems for denitrification.