E. Nsabimana et al., EFFECTS OF THE HERBICIDE ATRAZINE ON THE ACTIVATED-SLUDGE PROCESS - MICROBIOLOGY AND FUNCTIONAL VIEWS, Chemosphere, 33(3), 1996, pp. 479-494
Two pilot laboratory plants were used in order to assess the impact of
atrazine on the activated sludge process. At the steady state (15 day
s), one pilot received continuously, either 1 ppm of atrazine for 6 da
ys, or 20 ppm for 7 days. At 20 ppm, atrazine had an immediate effect
on COD which increased after 22 hours. After the 4(th) day, it reduced
MLVSS and bacterial concentration. Metabolic activities of the sludge
in oxidation of sewage (dehydrogenation), in proteolysis, as well as
in the nitrogen cycle, were not affected. Atrazine had no effect on di
fferent genera of protists present in the mixed liquor and was not bio
transformed. Among 6 bacterial strains isolated from sludges, none deg
raded this pesticide but the growth of Flavobacterium indologenes was
inhibited by 100 ppm. This therefore suggests that the decrease of bio
mass in sludge at 20 ppm of atrazine was due to the inhibition of some
bacteria. Copyright (C) 1996 Elsevier Science Ltd