System for removal of toxic heavy metals from drinking water

Abstract

Toxic heavy metal ions are removed from water by electrochemical replacement as the water flows through a tandem bed of (a) activated zinc and then (b) magnesium alloyed with a minor amount of manganese to inhibit corrosion. The zinc is activated by contact with a noble metal salt. Preferably, fine granules of zinc and Mg/Mn are used. Clogging is prevented by intermittent vacuum degassing of the beds. The activated zinc and the Mg/Mn advantageously are prepackaged and stored in cartridges which become part of the processing column. The Mg/Mn cartridge has a non-reactive atmosphere of e.g., argon, retained by frangible or soluble barriers that hermetically seal the ends of the cartridge. The barriers are torn away or dissolved by the initial water flow when the cartridge is installed. System scale-up is simplified by a 'half-length' concept characteristic of the present invention. Specifically, the heavy metal ion concentration is reduced by one-half for each additional fixed distance ('half-length') traversed through the reactant bed.