Influence of C-sources on the denitrification rate of a high-nitrate concentrated industrial wastewater

Two different carbon substrates (ethanol and acetic acid) were compared in order to set up the denitrification of a concentrated industrial wastewater (115 mM nitrate, 0 mM nitrite). Two stirred anaerobic reactors were carried out in continuous flow culture mode: one using ethanol as carbon source, and the other using acetic acid. The microorganisms, selected from the factory lagoon, were a mixed culture of Pseudomonas sp. and cocci sp. The variation of the dilution rate allowed the evaluation of the specific growth rate of the bacteria. In the two cases, the denitrification was complete. The experiments have shown that the development of the microorganisms was higher on ethanol, but on acetic acid, the specific denitrification rate was higher. The high specific denitrification rate observed with acetic acid was explained by the fact that acetic acid is a directly assimilable carbon source. The ethanol must be first changed into acetate. This studyʹs application is a fluidized bed pilot plant for the industrial wastewater treatment.