Use of carbon felt cathodes for the electrochemical reclamation of urban treated wastewaters

• Combined chlorine species and H2O2 are the main responsible of E. coli elimination.
• H2O2 avoids the formation of chlorate and other disinfection by-products with CDA.
• Fe–carbon felt allow to simultaneously removing E. coli and turbidity.
• Low power consumption disinfection with Fe and CDA anodes and carbon felt cathodes.

This work focuses on the application of electrolysis with carbon felt cathodes for the reclamation of actual effluents from municipal wastewater treatment facilities (WWTFs) in combination with different anode materials (dimensionally stable anodes-DSA, conductive diamond anodes-CDA and iron–Fe). First of all, the efficiency of electrodisinfection with CDA and DSA was assessed, finding that total elimination of Escherichia coli (E. coli) can be attained at applied electric charges below 0.03 Ah dm−3, and that the disinfection process is more efficient when using CDA. Furthermore, it was observed that the formation of hydrogen peroxide on carbon felt cathodes limits the concurrence of disinfection by-products (chlorates, perchlorates and organic chlorinated by-products), an interesting result that broadens the potential of CDA for the regeneration of urban wastewater. Results with Fe anodes show that it is possible to attain the complete removal of microorganisms with comparable efficiency to that of CDA (due to the contribution of Fenton's reaction) and that it was possible to totally remove the turbidity of the effluent when working at current densities from 12.50 A m−2. Finally, it was found that Fe is the most efficient anode material (lowest power consumption) at low current densities and CDA is the most appropriate one at current densities higher than 5 A m−2. According to these results, the pairs anode-cathode CDA-carbon felt and Fe–carbon felt behave as the most promising electrode materials to be applied in wastewater reclamation processes.

Figure optionsDownload as PowerPoint slide