ATRAZINE REMOVAL THROUGH BIOFILTRATION

Atrazine is a common contaminant of many surface-water supplies in Missouri and other areas in the midwestem United States. It is classified by the Environmental Protection Agency as a group C-possible human carcinogen, and it has other negative health impacts on human health as well. Currently the established minimum allowable concentration level in drinking water is 3.0 (mu)g/L. Many surface-water suppliers have reported a greater quantity of atrazine in their raw water than the allowable limits. Cometabolic biodegradation of atrazine under aerobic conditions are reported here. In a shake flask using acclimated cultures, the atrazine removal was as high as 70% with humic acid as the primary metabolite. With glucose and PTYG (peptone, tryptone, yeast extract, and glucose) media, the atrazine removals in these flasks were greater than 40%. Mannitol and sodium acetate were unable to support cometabolism of atrazine under the test conditions. Atrazine could be cometabolized by the microbial film in continuous-flow packed columns (Captpor media) with humic acid and PTYG media as the primary substrate. The atrazine removals varied from 30 to 35%. The presence of ammonium nitrate in the culture media did not inhibit atrazine biodegradation.