The effect of selected surfactants and heavy metal ions on the kinetics of the process of denitrification taking place with the involvement of Bacillus licheniformis bacteria has been studied. The limiting concentrations of the compounds studied and the coefficients of inhibition have been determined. A kinetic model of denitrification was carried out in a lactate medium with the addition of a quaternary ammonium salt APDA has been proposed. The process has been shown to occur according to the autocatalytic model of the second order with respect to nitrates (V) and proteins and first order with respect to nitrates (III) for the subseguent irreversible reaction.