The removal of COD and NH-N from atrazine production wastewater treatment using UV/O: experimental investigation and kinetic modeling.

In this study, a UV/O hybrid advanced oxidation system was used to remove chemical oxygen demand (COD), ammonia nitrogen (NH-N), and atrazine (ATZ) from ATZ production wastewater. The removal of COD and NH-N, under different UV and O conditions, was found to follow pseudo-first-order kinetics with rate constants ranging from 0.0001-0.0048 and 0.0015-0.0056 min, respectively. The removal efficiency of ATZ was over 95% after 180 min treatment, regardless the level of UV power. A kinetic model was further proposed to simulate the removal processes and to quantify the individual roles and contributions of photolysis, direct O oxidation, and hydroxyl radical (OH·) induced oxidation. The experimental and kinetic modeling results agreed reasonably well with deviations of 12.2 and 13.1% for the removal of COD and NH-N, respectively. Photolysis contributed appreciably to the degradation of ATZ, while OH· played a dominant role for the removal of both COD and NH-N, especially in alkaline environments. This study provides insights into the treatment of ATZ containing wastewater using UV/O and broadens the knowledge of kinetics of ozone-based advanced oxidation processes.