Conductive diamond sono-electrochemical disinfection (CDSED) for municipal wastewater reclamation

• Total and efficient disinfection of urban wastewater with CDEO is performed.
• Production of hazardous chlorine derivates is avoided at low current densities.
• Marked synergistic effect observed when coupling US irradiation and electrodisinfection.
• E. coli deagglomeration and improvement in oxidants production by US irradiation.

In the present work, the disinfection of actual effluents from a municipal wastewater treatment plant (WWTP) by a conductive diamond sono-electrochemical process was assessed. First, efficiency of single electrodisinfection process with diamond anodes (without the contribution of ultrasounds) was studied, finding that the total disinfection can be attained at current charges applied below 0.02 kA h m−3. It was also found that the main disinfection mechanism is the attack of Escherichia coli (E. coli) by the disinfectants produced in the electrochemical cell and that the production of chlorates is avoided when working at current densities not higher than 1.27 A m−2. Next, a marked synergistic effect was found when coupling ultrasound (US) irradiation to the electrochemical system (sono-electrochemical disinfection). This increase in the disinfection rate was found to be related to the suppression of the agglomeration of E. coli cells and the enhancement in the production of disinfectant species.