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

Year 2006, Volume: 19 Issue: 1, 75 - 84, 30.06.2006

Merve Temizer Oğuz

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. .

References

• [1] Metcalf and Eddy, Inc., “Wastewater Engineering: Treatment, Disposal and Reuse”; 3rd Ed. McGraw-Hill, New York, 1991.
• [2] Grady L.C.P.Jr, Daigger G.T., and Lim H.C., “Biological Wastewater Treatment”, 2nd Ed., Marcel Dekker, New York, 1999.
• [3] Okabe S., Satoh H., Watanabe Y., “In-Situ Analysis of Nitrifying Biofilms as Determined by In-Situ Hybridization and the Use of Microelectrodes”, Appl. Environ. Microbiol., Vol. 65, pp. 3182-3191, 1999.
• [4] Bock E., Koops H.P., Harms H., Ahlers B., “The Biochemistry of Nitrifying Organism”, pp. 171-200, in Variations in Autotrophic Life, Academic Press, New York, 1991.
• [5] Madigan M.T., Martinko J.M., and Parker J., “Biology of Microorganisms”, 8th Ed., Prentice-Hall, New York, NY, 1997.
• [6] Billen G., “A Method for Evaluating Nitrifying Activity in Sediments by Dark [14C]-bicarbonate Incorporation”, Water Res., Vol. 10, pp. 51-57, 1976.
• [7] Somville M., “A Method for Measurement of Nitrification Rates in Water”, Water Res., Vol. 12, pp. 843-848, 1978.
• [8] Glover H.E., “The Relationship Between Inorganic Nitrogen Oxidation and Organic Carbon Production in Batch and Chemostat Cultures of Marine Nitrifying Bacteria”, Arch. Microbiol., Vol. 142, pp. 45-50, 1985.
• [9] Belser L.W., “Bicarbonate uptake by nitrifiers: Effect of growth rate, pH, substrate concentration and metabolic inhibitors”, App. Environ. Microbiol., Vol. 48, pp. 1100-1104, 1984.