Investigating the enzymatic biodegradation of atrazine in the H2O2-stimulated SBR bioreactor

S-triazine is a class of herbicides which includes atrazine, simazine, ametryn, and prometryn. Atrazine is one of the most commonly used s-triazine herbicide. Atrazine is amongst the most persistent pollutants in water resources that is toxic for various living microorganisms. The aim of this study was investigation of atrazine removal using hydrogen peroxide-activated peroxidase enzyme. Atrazine samples were synthetically prepared. Experiments were carried out in 1000 mL sequencing batch reactor (SBR). Initial experimental phases including acclimation and enrichment of atrazine degrading bacteria were conducted. The effects of initial concentration of atrazine (25 - 100 mg/L), the effect of concentration of hydrogen peroxide H2O2 and microbial activity were studied. During the experiments, concentration of atrazine was measured using HPLC. Likewise, the pH value was controlled and set about 7 during the entire process.In this study, acclimation period was 72 days and Complete removal of atrazine in all tested concentrations and from 22 d in one of step to 1 d in final of step was obtained. Optimal ratio H2O2/ATZ equal to 11 that ATZ concentration 25 mg/L with concentration of  H2O2 to the 7.5 mM in HRT 24 h completely removed. In ATZ concentrations of 25 and 100 mg/L on times 15 and 54 h removal complete was done. with increasing concentration of ATZ from 25 to 50 mg/L dehydrogenase enzyme activity increased from 8.8 to 9.7 TF/g biomass.d.  Based on the obtained results, atrazine degradation using peroxidase enzyme in presence of hydrogen peroxide is a novel and efficient enzymatic method for degradation of this pollutant in aquatic environments.