Remoção biológica de nitrogênio via nitrito utilizando fenol como fonte de carbono

Abstract

The present survey studied the transformation of ammonia nitrogen directly to nitrate, using phenol as source of carbon in the anoxic stage. A pilot sequential biological reactor was operated (volume of 20 liters), fed with 5.0 liters of synthetic wastewater. The research was characterized by a gradual increase of the concentration of ammonia nitrogen (200, 300 and 500 mgN‐NH3/L) in the affluent, and an effort to find operational conditions for the predominance and prevalence of the nitrite at the end of the aerobic phase. Phenol (1,000 mg/L) was used as the only source of carbon by the heterotrophic microorganisms for reduction of the nitrogen oxidized during the anoxic phase. Predominance of nitrite was observed at the end of the aerobic phase throughout the experiment. At the aerobic phase the pH was controlled close to 8.3; the temperature ranged between 25 and 33°C, and the dissolved oxygen concentration was maintained next to 1.0 mgO2/L. The efficiency of removal of N‐NH3 was over 93%; the relation N‐NO2 / (N‐NO2 + NNO3) ranged between 88 and 97%. The specific nitrification rate ranged between 0.04 and 0.06 kg N‐NH3 / kg VSS.day for a concentration of VSS in the range of 2,175 to 2,645 mg/L. Phenol was adequate as a source of carbon for concentrations of 200 to 300 mgN‐NH3/L The rate of "specific denitrification” ranged between 0.018 and 0.049 kg N‐NO2/ kg VSS.day. The F/M ratio remained in the range of 0.05 to 0.09 kg Phenol/kg VSS.day. For concentrations of N‐NO2 in the reactor over 75 mg/L, the experiment using phenol as the only source of carbon was severely inhibited.