Preliminary Study and Numerical Investigation of an Electrostatic Unit for the Removal of Fluoride from Thermal Water of Ethiopian Rift Valley

This work deals with the numerical modeling of the multiphysics investigation of an electric-field based device for the defluoridation of Ethiopian water to mitigate fluorosis while satisfying the WHO quality requirement for potable water. A tubular reactor with metallic parallel plates, connected to a static voltage source, exerts an electric force on the ion in solution, attracting it to the electrodes. Meanwhile the ion drifted by the laminar water flow which, in turn, allows to separate and collect the F-rich stream from the potable one. In this system the electrostatic problem and the mass transport are coupled according to the highly non-linear modified Poisson-NernstPlanck-Stokes equations system. Therefore, carefully modeling the dielectric permittivity, the ionic diffusivity and mobility as function of fluoride concentration and temperature, the set of operating parameters to ensure the highest fluoride removal from Ethiopian thermal water are identified.