Simultaneous removal of nitrate and atrazine from groundwater

The objective of this research was to study the simultaneous removal of atrazine and nitrate by Pseudomonas ADP in a continuous reactor. Results obtained from batch experiments demonstrated that P. ADP kept the ability to degrade and mineralize atrazine under both aerobic and anoxic renditions. Results from fluidized bed reactors with P. ADP proved efficient biological removal of both nitrate and atrazine. Atrazine degradation in all the readers studied and under all operational conditions followed the same pattern: First phase, which lasted for 3-5 weeks, with atrazine degradation of about 95% conversion, followed by a second phase where atrazine degradation efficiency decreased gradually, reaching a value of between 10-25%. Results from sterile and non-sterile chemostats experiments indicated that the reason for the decrease in atrazine degradation activity in the continuous reactors was due to the penetration of foreign denitrifying bacteria which did not have the ability to degrade atrazine.