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, RuO ₂/Ti anodic oxidation (AO), AO in the presence of electro-generated H ₂O ₂ (AO-H ₂O ₂), 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 6.66mA/cm ², a pH of 3, and a concentration of 1mM of Fe ²⁺ 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 BOD ₅/COD and the BOD ₁₄/COD ratios. The EF did not effectively remove the COD, but removed enough to achieve suitable biodegradability for a further biological process.