Electro-Fenton Process at Semi-Pilot Scale: A Study to Enhance Bisphenol A Biodegradability

In this study, we report the development of an electro-Fenton (EF) process at a semi-pilot scale plant using an open undivided electrochemical reactor design. To do so, a series of three-dimensional (3D) cathodes constituted of packed and fixed beds of glassy carbon pellets and dimensionally stable anodes (DSAs) were employed. To highlight the treatment efficiency of the EF process, bisphenol A (BPA), which is known to be a persistent molecule, was used as the model molecule. First, the applied current intensity was studied and optimized to determine the limiting current of the O2 reduction under hydrodynamic conditions of 0.6 m3·h−1. The limiting current intensity under hydrodynamic conditions corresponding to 10 L·min−1 (600 L/h) was determined to be near 17.5 A (0.51 A/100 g of glassy carbon pellets). Then, the effect of the number of cathodes on the removal efficiency of BPA versus the time of the electro-Fenton treatment was investigated. The value of Kapp in the typical reactor configuration was found to be 0.076 min−1. Many parameters were carried out using the EF reactor, i.e., the effect of the initial pollutant concentration as well as the effect of the treatment flow rate. The obtained results demonstrate that the degradation efficiency of BPA increases as the number of cathodes increases and the pollution charge decreases. Only a few seconds of treatment by EF process were needed to eliminate BPA from the dilute solutions (≤10 mg·L−1). The biodegradability of the treated solution and its mineralization were also investigated by referring to the measurements of COD, TOC, and BOD5. Finally, strategy of scaling-up the reactor design to an industrial pilot plant is discussed.