An immobilized cell bioprocess for the removal of heavy metals from aqueous flows

Microorganisms can be used to remove toxic heavy metals from liquid industrial wastes. In addition to the chemical toxicity of many of the latter, the production of long-lived nuclides from nuclear power programmes has introduced additional radiotoxicological hazards. Associated problems of the presence of contaminating, non-metal co-pollutants and the presentation of dilute, high-volume wastes have received little attention. Traditional biotechnological waste treatments have relied either on the use of non-living biomass ('biosorption') or on the accumulation of metals by living cells with the associated problems of metal toxicity effects and the requirements for cell viability or growth. Identification of an enzymically-mediated metal accumulation step can permit decoupling of cell growth from metal accumulation. Using pre-grown biomass immobilized in a flow-through filter ('bioreactor') the metal-accumulative bioprocess can be described accurately applying traditional Michaelis-Menten kinetics. The effect of co-pollutants can be then quantified in order to run the bioreactor in the most efficient way.