Simultaneous removal of nitrate and atrazine from groundwater

The objective of this research was to study the simultaneous removal of atr azine and nitrate by Pseudomonas ADP in a continuous reactor. Results obtai ned from batch experiments demonstrated that P. ADP kept the ability to deg rade and mineralize atrazine under both aerobic and anoxic renditions. Resu lts from fluidized bed reactors with P. ADP proved efficient biological rem oval of both nitrate and atrazine. Atrazine degradation in all the readers studied and under all operational conditions followed the same pattern: Fir st phase, which lasted for 3-5 weeks, with atrazine degradation of about 95 % conversion, followed by a second phase where atrazine degradation efficie ncy decreased gradually, reaching a value of between 10-25%. Results from s terile and non-sterile chemostats experiments indicated that the reason for the decrease in atrazine degradation activity in the continuous reactors w as due to the penetration of foreign denitrifying bacteria which did not ha ve the ability to degrade atrazine.