Evaluation of the effect of the rotational electrode speed in an electrochemical reactor using computational fluid dynamics (CFD) analysis

High concentrations of hexavalent chromium (Cr(VI)), which is a hazardous substance, can be found in the wastewaters generated by the electroplating industry. High-cost treatments have been applied to remove Cr(VI) from industrial wastewaters. Simple treatments such as chemical precipitation methods use great quantities of chemical and flocculating agents that produce large quantities of sludge, which, in turn, must be treated, handled, and disposed, thus increasing the process costs. The electrochemical process is an alternative method to remove Cr(VI) from industrial wastewaters. During the process, a film of oxides is formed on the surface of the electrodes (passivation effect), reducing both the Fe(II) transfer to the bulk liquid and the process efficiency, while increasing the energy consumption. In this work, rotating electrodes were used to increase the mass transfer of Fe(II) to the bulk liquid and avoid the salt film formation on the electrodes. Using industrial wastewater, different electrode rotating rates were tested and their effect on the treatment time was measured. The turbulence intensity was evaluated by computational fluid dynamics (CFD) analysis.