Abstract: This invention concerns the electrochemical removal of metal ions and certain other contaminating ions from aqueous solutions and moist gas streams. Direct current from an external source is caused to flow through electrically conductive particulate elements or packing forming a bed of low electrical conductivity from two or more oppositely charged spaced electrodes maintained in direct physical contact with conductive particulate elements or packing. The aqueous solution or moist gaseous stream to be treated is brought into contact with the conductive bed while current is supplied to the electrodes and flows through the bed. The characteristics of the system are such that each bed element exhibits bipolar properties causing a multiplicity of electrically positive and negative sites to exist within the bed at which electron transfer with the pollutant ions occurs, changing their state and effectively removing them from the fluid.