Process for the removal and recovery of heavy metals from aqueous solutions

A continuous process for reducing the concentration of water soluble heavy metal ions in an aqueous solution containing the same comprising:

• providing an aqueous waste solution containing sulfate ions and water soluble ionic heavy metal species capable of reacting with hydrogen sulfide to form water insoluble heavy metal species, said aqueous waste solution having a pH ranging from about 6 to about 11;
• providing a porous matrix containing a population of Desulfovibrio bacteria, said bacteria being capable of reducing said sulfate ions to hydrogen sulfide, said matrix being under anaerobic conditions;
• continuously passing said aqueous waste solution through said porous matrix at a rate up to about 820.0 liters of the aqueous waste solution per square meter of the porous matrix per day, in the presence of at least one nutrient capable of acting as a carbon source and selected from the group consisting of starches, sugars, organic acids, biological municipal waste water sludges and waste byproducts, said waste byproducts resulting from the metabolic reduction of at least one organic material selected from the group consisting of cellulose, hemicellulose, pectic substances, inulin, chitin, lignin, proteins, amino acids, hydrocarbons and derivatives thereof and in the presence of at least one trace nutrient and at temperatures ranging from about 0.degree. C. to about 65.degree. C. said nutrients and said temperatures providing for the growth and steady state population density of the bacteria in said matrix, to contact said sulfate ions with said Desulfovibrio bacteria and thereby metabolically reduce at least a portion of said sulfate ions to hydrogen sulfide which reacts with at least a portion of the water soluble ionic heavy metal species to form water insoluble heavy metal species, which substantially are retained on the porous matrix;
• and
• continuously separating from said porous matrix an aqueous effluent containing a reduced concentration of said water soluble ionic heavy metal species.