The passage of electric current through interfaces between media with different electrochemical properties is accompanied by changes in the solution composition close to the interfaces (concentration polarization). Another phenomenon occurring at solid-liquid interfaces is the charge separation and formation of (equilibrium and non-equilibrium) double electric layers. Subject to external and/or spontaneously arising electric fields and ion-composition gradients, the space charges give rise to volume-transfer phenomena. Their intensity is strongly dependent on the ion composition of the liquid phase, which can change considerably close to current-polarized interfaces. This is one of the mechanisms of coupling between the ion- and volume-transfer phenomena in heterogeneous systems. At the same time, the space-charge-related volume transfer can strongly modify the solution composition close to polarized interfaces via convective transfer of solutes. This is another mechanism of coupling between the phenomena of interest. The interplay of these two mechanisms gives rise to a number of non-linear, non-1D and non-stationary phenomena. Their modeling is difficult but important for the optimization of applications in clean energy, advanced water treatment, micro-analysis, and so on. Because of complexity of the objects involved, such a model cannot be formulated from first principles and has to use input parameters determined experimentally. Therefore, fundamental experimentation is an indispensable constituent part of the modeling effort.Important elements of this model and/or corresponding fundamental experimentation have been developed in the previous studies of the Proposers. The purpose of this project is to facilitate the knowledge transfer between them to make possible further development and integration of these elements into a self-consistent and comprehensive model. Its utility will be validated via optimization of several practically-relevant systems/processes.