Investıgatıon Of Nıtrıfyıng Bacterıal Actıvıtıes Durıng Wastewater Treatment Usıng Actıvated Sludge Process

Authors : Merve TEMİZER OĞUZ

Pages : 75-84

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Publication Date : 2006-06-30

Article Type : Research Paper

Abstract :The activity of nitrite oxidizing bacteria (NOB)   during activated sludge wastewater treatment was investigated by monitoring nitrite oxidation, nitrate formation and carbon dioxide fixation. Nitrite oxidation, nitrate removal and carbon dioxide (CO2) fixation assays in batch experiments were performed using mixed liquor samples obtained from a complete-mix, bench-scale, activated sludge reactor. Nitrite oxidation resulted in a 1:1 ratio (nitrite removal to nitrate formation) with equal rates in the batch samples. This ratio suggests conversion of all consumed nitrite to nitrate based on the stoichiometry of the reaction of nitrite oxidation in which 1 mol of nitrite-N is converted to 1 mol of nitrate-N. The mean assimilated inorganic carbon was 20.3 µg/L and the mean carbon dioxide fixation rate was calculated as 4.06 µg/L-hr. The ratio of carbon incorporated to nitrogen oxidized was 1.42 x 10-3.  Additionally, it was demonstrated that there was a connection between nitrite removal, nitrate formation and CO2 fixation. Also, it was shown that uptake of inorganic carbon can be exploited as a method by which to demonstrate the in-situ activity of nitrifying bacteria.  
Keywords : Nitrite oxidation, nitrate formation, carbon dioxide fixation, activated sludge, wastewater treatment