ABSTRACT
Nitrification, the oxidation of ammonia tp nitrate catalyzed by bacteria, is a key part of global nitrogen cycling. In the first step of nitrification, chemolithoautotrophic ammonia oxidizers transform ammonia to nitrite, which is subsequently oxidized to nitrate by nitrite-oxidizing bacteria. This process can be affected by several factors. In this study the effect of influent COD/N ratio on nitrification rate in a bench-scale biological reactor was investigated. Experiments were carried out using synthetic wastewater. The initial ammonium concentration was 25 mg NH[4]-NL[-1]. The effect of COD/N ratio between 10.0l +/- 0.083 and 24.08 +/- 0.22 gCODgN[-1] on nitrification rate were investigated by varying the COD loading supplied to the reactor. From the results obtained in this study it is found to be in the range of 10.01 +/- 0.083 to 14.15 +/- 0.17 gCODgN[-1], there is a direct relationship between COD/N ratio and nitrification rate. However, more than 14.15 +/- 0.17 up to 24.08 +/- 0.22 gCODgN[-1] was found to exhibit an indirect relationship between the ratio and rate