STUDY OF PHYSICOCHEMICAL FACTORS CONTROLLING NITRITE BUILDUP DURING HETEROTROPHIC DENITRIFICATION

The effects of temperature, pH and C/N ratio on nitrite build-up were studied, using a denitrifying bacteria, an ammonia producing bacteria and a nitrate reducing consortium. High temperature (with respect to the range of temperatures examined: 12.5 degrees C to 35 degrees C) and alkaline pH (8.5) were favourable to nitrite accumulation. C/N ratio did not seem to have any effect on this phenomenon. On the other hand, for all the C/N ratios studied, an increase in the initial nitrate concentration induced an increase in nitrite build-up. In every case, the microbial consortium was more efficient in the elimination of all the nitrogen oxides than the pure strains used in this study. In all experiments with this consortium, maximum amounts of nitrite measured in the culture media during the experiments were very low, and at the end of the experiment, no nitrite was detected in the media.