Electron beam irradiation applied for the detoxification and degradation of single ciprofloxacin aqueous solution and multiclass pharmaceutical quaternary mixture

The application of electron beam irradiation for detoxification and degradation of single antibiotic ciprofloxacin (CPF) and in a mixture with multiclass pharmaceuticals in aqueous solutions was carried out. Ecotoxicity assays indicated that the green algae were most sensitive to antibiotic and also that the presence of several pharma-ceutical increased the toxicity. After the irradiation treatment, degradation results of single antibiotic indicated reduction of 95.86 % at 1.0 kGy. Total organic carbon decreased up to 38 % at 5.0 kGy. At lower doses (1.0 kGy), no effect in toxicity was evidenced, however, increase in toxicity for Vibrio fischeri was observed after 2.5 kGy. For Daphnia similis exposure, an increase in toxicity was noted for all applied doses. In contrast, for the green algae R. subcapitata toxicity reduction varied from 62.3 to 81.9 % at the evaluated doses. Toxicity assays to microbes E. coli and S. aureus reduced antibacterial activity of CPF after irradiation treatment. Regarding the irradiated quaternary mixture at 2.5 kGy, reduction up to 96 % was achieved for the ciprofloxacin, metformin and acetylsalicylic acid, and 81 % removal was achieved for fluoxetine. Acute assays with V. fischeri indicated no increase in toxicity, while some increase was noted for D. similis (acute effects). Nevertheless, chronic assays data indicated low toxicity reduction (14 %) with D. similis, and complete detoxification was shown for the green algae after the irradiation. In addition, decrease in antimicrobial activity was noted after the treatment. Furthermore, the in-silico model was not enough accurate for the prediction of CIP toxicity. These findings showed that electron beam irradiation can be applied for reducing the impacts of antibiotics in aquatic ecosystem. Measuring toxicity on living-organism from different trophic levels are useful tools to evaluate the interaction of mixtures and also to assess toxicity of the generated byproducts.