Facing the treatment of polymedicated effluents using gaseous ozone electrochemically generated

Abstract

The degradation of antibiotics in hospital urine, as alternative to reduce the chemical risk of hospital effluents, is evaluated by gaseous ozone electrochemically generated in Polymer Electrolyte Membrane (PEM) cells. Firstly, the influence of the current density in the electrochemical step is evaluated. The results indicate that ozone gas with rates ranging from 0.034 to 1.111 mg O3 min−1 can be produced by applying current densities of 21–125 mA cm−2. Then, the degradation of Penicillin G (Pen G) by electrochemically generated ozone is evaluated. Results show that the degradation rate is dependent on the ozone dose flow rate and the aeration system plays a crucial role in enhancing the efficiency of the ozonation process by reducing the limitations associated with gas-liquid mass transfer. Under the optimal conditions, using an ozone dosage of 1.111 mg O3 min−1, 100 % efficiency of Pen G (50 mg dm−3) removal in hospital urine is achieved after 13 min, resulting in a ratio of 1.04 mg Pen G removed per mg O3 supplied. Finally, the efficiency of electrogenerated gaseous ozone for treating a simulated polymedicated hospital urine (using data from the University Hospital Complex of Albacete (Spain) as case of study) is tested. The findings suggest that the chemical risk associated with hospital urine is mitigated (reducing antibiotic activity by 100 %) by breaking down pharmaceutical compounds into simpler molecules that no longer possess antibiotic properties. Degradation efficiencies over 2 g (kWh)−1 make of this treatment a cost-effective alternative to treat hospital effluents.