the general objective of this study was to develop a highly efficient, economical andintegrated technology for the removal of nitrogen compounds through denitrification via nitrite. toachieve this, a modified uasb reactor was designed, set-up and operated using chilean zeolite asmicrobial support. the results were compared to a conventional uasb reactor used as control. thevolume of each reacto...

the general objective of this study was to develop a highly efficient, economical andintegrated technology for the removal of nitrogen compounds through denitrification via nitrite. toachieve this, a modified uasb reactor was designed, set-up and operated using chilean zeolite asmicrobial support. the results were compared to a conventional uasb reactor used as control. thevolume of each reacto...

Nitrate and nitrite concentrations in the water and nitrous oxide and nitrite fluxes across the sediment-water interface were measured monthly in the River Colne estuary, England, from December 1996 to March 1998. Water column concentrations of N(2)O in the Colne were supersaturated with respect to air, indicating that the estuary was a source of N(2)O for the atmosphere. At the freshwater end ...

The feasibility of removing nitrogen from mature landfill leachate using the nitrite route was investigated in a two-stage SBR system – (1 first stage, short-cut nitrification; second stage, denitrification via nitrite. With a volumetric exchange rate (n) of 0.3 d and an oxygen concentration of between 1.2 and 1.3 mg/L, the nitrite accumulation ratio – (NO2-N)×100/(NOx-N)% – was between 32% and...

Sequencing biofilm batch reactor (SBBR) was used to achieve simultaneous nitrification and denitrification (SND) in current study. With SBBR, microorganisms are immobilized on fillers as biofilm, which results in high biomass hold up and enables the process to be operated at high liquid throughputs and organic loading rates [1]. Compared with sludge-based systems, SBBR is generally less energy ...

During anaerobic nitrate respiration Bacillus subtilis reduces nitrate via nitrite to ammonia. No denitrification products were observed. B. subtilis wild-type cells and a nitrate reductase mutant grew anaerobically with nitrite as an electron acceptor. Oxygen-sensitive dissimilatory nitrite reductase activity was demonstrated in cell extracts prepared from both strains with benzyl viologen as ...

Induction and repression of denitrification activity were studied in a continuous culture of Paracoccus denitrificans during changes from aerobic to anaerobic growth conditions and vice versa. The denitrification activity of the cells was monitored by measuring the formation of denitrification products (nitrite, nitric oxide, nitrous oxide, and dinitrogen), individual mRNA levels for the nitrat...

The phenotypes of three different Nitrosomonas europaea strains--wild-type, nitrite reductase (NirK)-deficient and nitric oxide reductase (NorB)-deficient strains--were characterized in chemostat cell cultures, and the effect of nitric oxide (NO) on metabolic activities was evaluated. All strains revealed similar aerobic ammonia oxidation activities, but the growth rates and yields of the knock...

The occurrence of denitrification and nitrate respiration among eukaryotes has been established during the last few decades. However, denitrification-related eukaryotic genes have been isolated from only a few fungi, and eukaryotic denitrification (or nitrate respiration) is still inadequately understood. In this study, we identified genes that were up-regulated under denitrifying conditions in...

This research investigated spatial-temporal variation in benthic bacterial community structure, rates of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) processes and abundances of corresponding genes and transcripts at three sites-the estuary-head, mid-estuary and the estuary mouth (EM) along the nitrate gradient of the Colne estuary over an annual cycle. Denitrification...