An apparatus and a method for electrochemical modification of liquid streams using at least one anode and cathode assemblies arranged to contain liquid electrolytes anolyte and catholyte, a plurality of electrically conducting anode and cathode particulates forming anode and cathode particulate beds, and current feeder and current collector devices in contact with the particulate bed, where the anode particulates and cathode particulates are in motion substantially independent of bulk electrolytes flow.