The effect of antibiotics on nitrification processes. Batch assays.

The effect of different antibiotics at several concentrations of ampicillin (0-250 mg/L), benzylpenicillin (0-250 mg/L), novobiocine (0-150 mg/L), oxytetracycline (0-250 mg/L), and chloramphenicol (0-50 mg/L) on a stabilized nitrifying sludge was evaluated under aerated and lithoautotrophic conditions. No effect resulting from the presence of antibiotics on the biomass and nitrate production was noticed. The specific growth rate and volumetric nitrification rate average values for the controls were 8.28 x 10-3/h-1 and 2.74 x 10-3 g/L.h, respectively. Similar rate values were found when different kinds of antibiotic and concentrations were tested. These results may be explained by the nature of the floc or the instability of the antibiotics.