Scaled-up electrochemical reactor with a fixed bed three-dimensional cathode for electro-Fenton process: Application to the treatment of bisphenol A

In this study, we report on the development of an open undivided electrochemical reactor with a compact fixed bed of glassy carbon pellets as three-dimensional cathode for the application of electro-Fenton process. Bisphenol A (BPA) was chosen as model molecule in order to improve its efficiency to the treatment of persistent pollutants. The study of the BPA removal efficiency in function of the applied current intensity was investigated in order to determine the limiting current of O-2 reduction (optimal conditions of H2O2 production at flow rate of 0.36 m(3).h (1)) which was 0.8 A (0.5 A/100 g of glassy carbon pellets). Many parameters have been carried out using this electro-Fenton reactor namely degradation kinetics, influence of anodic reactions on DSA, effect of initial pollutant concentration. In the optimal current condition, the global production rate of H2O2 and (OH)-O-center dot was investigated. The yield of electroFenton reaction (conversion of H2O2 (OH)-O-center dot) was very high (> 90%). The absolute rate of BPA degradation was determined as 4.3 x 10(9) M (1) s (1). COD, TOC and BOD5 measurements indicated that only few minutes of treatment by electro-Fenton process were needed to eliminate BPA for dilute solutions (10 and 25 mg. L (1)). In this case, the biodegradability of the treated solutions occurred rapidly. For higher concentration levels, an efficient removal of BPA appeared for treatment time higher than 1 hour and more than 90 minutes were necessary to obtain the biodegradability of BPA solutions. In optimum conditions, the scale-up of the electrochemical reactor applied to electro-Fenton process was suggested and depended on the concentration level of the pollutant. The operating parameters of the scaled-up reactor might be deduced from the new section of each fixed bed exposed to the flow, from values of liquid flow velocity and from the corresponding limiting current density obtained with the reactor at laboratory scale. The compact fixed bed cathode in an open undivided electrochemical reactor appears as an appropriate solution as pre-treatment electro- Fenton process followed by the biological treatment of persistent pollutant. (C) 2016 Elsevier Ltd. All rights reserved.