FACTORS AFFECTING BIOLOGICAL OXIDATION OF NITROGEN

RUIZ F.; CONTRERAS E.; BERTOLA N.

Campeche, Mexico

Simposio; Fifth Latin American Biodegradation and Biodeterioration Symposium (LABS5); 2004

Abstract   Respirometric techniques have been intensively used for the determination of BOD, toxicity and biokinetic parameters of toxic and non-toxic wastewater. In this paper the effect of pH, ammonia, nitrite, and nitrate concentrations on the nitrification rate was studied using a respirometric technique. The nitrifying activated sludge was obtained from a laboratory scale completely mixed, continuous-flow activated sludge reactor. Synthetic wastewater was used with an ammonia nitrogen concentration of 500 mgN/l and devoid of carbonaceous substrate; the pH was controlled at 8 ± 0.2 by adding a solution of Na2CO3 (1M) used as pH buffer and carbon source for nitrifying bacteria. The oxygen uptake rates (OUR) of nitrifying bacteria were measured in batch tests. The tested values of pH ranged between 6.0 to 9.5; ammonia, nitrite, and nitrate concentrations ranged between 0 to 3000 mgN/l. OUR was pH dependent with a maximum value in the 7.5-8 range.  OUR was not affected by ammonia and nitrate within the tested concentrations; however, at high concentrations of nitrite a partial OUR inhibition was observed.