Evaluation of the hydrodynamic performance of an electrochemical reactor with rotating ring electrodes using CFD analysis

Chemical precipitation, ion exchange, evaporation and reverse osmosis processes have been applied to remove hexavalent chromium Cr(VI) from industrial wastewaters. However, some of chemical precipitation methods use great quantities of chemical and flocculating that produce elevated quantities of sludge that must be treated, handled and disposed, increasing the process costs. The other methods require high capital and operating costs. The electrochemical process is an alternative method to remove Cr(VI) from industrial wastewaters process. However, in electrochemical plug flow reactors with no liquid mixing or static electrodes, iron salt film is formed on the electrodes surface (electrode passivation) because of the poor diffusion and mass transfer that reduces the Cr (VI) removal efficiency and causes greater energy consumption. Therefore, the electrochemical reactors require to be designed to provide high mass transfer between the bulk liquid and the electrodes. However, their performance generally has been evaluated as if they were a "black box". In this work, the performance of an electrochemical reactor with rotating ring electrodes was evaluated using state-of the-art computational fluid dynamics (CFD) tools at different rotational speeds to evaluate their effect on the electrochemical process to remove Cr(VI) from wastewater.