Scaling-up an integrated electrodisinfection-electrocoagulation process for wastewater reclamation

Abstract

This work focuses on the scale-up of an integrated electrodisinfection-electrocoagulation (ED-EC) process, especially suited for the reclamation of actual urban treated wastewater, equipped with Boron Doped Diamond (BDD) anodes and iron bipolar electrodes. The system operates in continuous mode and in the prototype the anode area was increased three times (anodic oxidation) and the bipolar electrode area fifteen times (electrocoagulation) with respect to the system used at bench scale. Results show that it is possible to attain the complete and simultaneous disinfection and turbidity removal by applying current densities within the range 5–10 A m−2. Free and combined chlorine species were electrogenerated from the chloride contained in the effluents (no reagents were added) being these species responsible for the removal of microorganisms. Likewise, iron coagulant species coming from the electro-dissolution of the anodic side of bipolar electrodes promote turbidity removal. In the scaled-up prototype, a more efficient turbidity removal was achieved, because of the increase in the bipolar electrode area. Finally, it was probed that for electric charges below 0.07 kAh m−3 the reclamation of urban treated wastewater could be reached, avoiding the formation of hazardous chlorates and perchlorates even at current densities higher than 7 A m−2.