the collapse of the bed to release the solid particles the reactor is ideal for the reduction of suspensions the large specific surface area given by the porous electrode is very attractive for a process permitting a small current exchange per surface unit additionally this morphology allows to increase the coefficient of mass transfer because it acts as a turbulence promoter for the electrolyte moving through the bed the contact between particles in suspension and the granular material is optimal and the pressure drop through the reactor remains moderate the use of the electrode as a carbonated granular material permits to obtain good productivity per volume unit of the reactor for the reduction of vat dyes and sulfur dyes the process can so be used for vatting operation in the process of coloration the configuration of the dragged bed electrode presents an interesting configuration to bring in contact a gas phase a liquid phase the electrolyte and a solid phase the electrode in order to allow an electrochemical transformation for example it was demonstrated that oxygen could be transformed electrochemically into h 2 o 2 on the same material as the one which is used for the reduction of coloration vat dyes and sulfur dyes the way to transform an electrochemically heterogeneous mixture with high performances is particularly interesting because of the possibility to avoid some separation processes the invention allows electrochemical transformations in homogeneous electrolytes suspensions emulsions foams etc the invention can find a lot of applications in the chemical industry reduction or oxidation of organic and inorganic compounds and also in the biotechnological industry for example for the regeneration of the cofactors according to the scheme as given in fig3.