Biodegradability enhancement of wastewater containing cefalexin by means of the electro-Fenton oxidation process

The comparative degradation behavior of cefalexin (CLX) using advanced oxidation processes (AOPs) with the aim of improving CLX biodegradability was studied. Among the AOPs used, RuO2/Ti anodic oxidation (AO), AO in the presence of electro-generated H2O2 (AO-H2O2), and the electro-Fenton (EF) process, the EF process was the most effective. In the EF process an activated carbon fiber (ACF) was used as a cathode. Different input variables, including catalyst concentration, pH, and current density were evaluated to find the optimum conditions for the EF. The most suitable operational conditions were as follows: a current density of 6.66 mA/cm(2), a pH of 3, and a concentration of 1mM of Fe2+ as the catalyst. Different CLX concentrations were analyzed as well of different reaction times to assess the degree of mineralization. The change in biodegradability was evaluated by the BOD5/COD and the BOD14/COD ratios. The EF did not effectively remove the COD, but removed enough to achieve suitable biodegradability for a further biological process. (C) 2012 Elsevier B.V. All rights reserved.