EN
The effect of glutaraldehyde (GA) in different concentrations on microbiological activities of Bacillus licheniformis, Desulfotomaculum ruminis and Thiobacillus ferrooxidans bacteria used in the processes of denitrification, desulfurication and iron (II) oxidation, respectively, has been tested. For the sake of comparison, the effect of formaldehyde (FA) on the activities of the same organisms in the same conditions has been studied. The tolerated and toxic concentrations of the aldehydes were determined.