MICROFLORA OF DISSIMILATIVE NITRATE REDUCTION IN A DENITRIFYING REACTOR

The predominant denitrifiers and ammonifiers from methanogenic, aerobi c and denitrifying reactor sludge were isolated and characterised. The population of ammonifiers increased by three orders of magnitude duri ng the operation of the denitrifying reactor treating landfill leachat e. The predominant ammonifiers were enterobacteria, and the predominan t denitrifiers belonged to the genera Alcaligenes and Pseudomonas. Stu dies in pure culture showed that ammonia production by ammonifiers was favoured by fermentable substrates and by high C/N ratios. For acetat e, only nitrite was obtained as the reduction product of nitrate, even at high C/N ratios. Furthermore, for glucose, nitrite addition caused a shift in fermentation products, with an increase in the acetate/eth anol ratio, with no significant differences in growth rates.