Bio- Electro-Fenton process: Application to the antiviral Ribavirin mineralization in aqueous medium

This work focuses on applying a combined process combining electro-Fenton (EF) pretreatment with biological degradation to mineralize the antiviral Ribavirin in an efficient, economical and ecological manner. First, the main experimental parameters affecting the efficiency of the electro-Fenton process, namely applied current intensity, Fe(II) catalyst concentration and initial Ribavirin concentration were evaluated and optimized. Indeed, the mineralization rate reaches maximum residual values of 99% after 4 hours of electrolysis applying a current of 200 mA. This mineralization is accompanied by an increase in biodegradability, evaluated from the BOD5/COD ratio, which goes from 0.04 at the beginning of treatment (1 h) to 0.45 after 2 hours of electrolysis, demonstrating the feasibility of a biological treatment. In addition, the energy efficiency decreased when the treatment time was extended due to the limitation of mass transport. Thus, the feasibility of coupling electro-Fenton and biological treatment has been successfully demonstrated on a laboratory-scale was, achieving a 96.66% removal rate by the Bio-EF process. A Box-Behnken design based on response surface methodology was applied to develop a model for predicting Rib removal rate. The interaction of factors such as Rib concentration (X1), catalyst concentration (X2) and electrolysis time (X3) was analyzed to identify optimal operating conditions. The model results obtained are statistically significant with an R2 of 0.99, indicating that the proposed model is significant and relevant. In addition, the iso-response curves obtained enabled us to determine the optimal experimental conditions required for effective mineralization of the targeted antiviral.