The purpose of this work was to study the basic construction, energy, and technological features of the electrochemical reactors used in the manufacture of whey, a dairy by-product and a biologically very valuable liquid. The choice of optimal regimes for processing various types of whey was specified aimed at increasing the efficiency of the recovery of whey protein fractions in the protein-mineral concentrates through reduction of the energy consumption. It is demonstrated that features of the electric reactors must be reasonably selected, including the distances between the electrodes and between the electrodes and the membrane, as well as their geometric shape, to avoid occurrence of dead areas and to ensure a high efficiency of the process. It was also important to find the most appropriate options for electric parameters and processing regimes (periodic or continuous). In addition, the ratio of the whey volume and the main electrode area, the type of the regimes membrane, the initial content of the dry matter in each type of the whey (in particular, its protein composition), and the compositions and concentration of the anodic (secondary) liquid, were taken into account. The results of the study are significant for the development of a wasteless technology of processing the dairy by-products.