The effect of anions on uranium accumulation by free and immobilized cells of aCitrobactersp. Implications for the treatment of metal‐bearing liquid wastes

Abstract
Many metal‐bearing wastes are highly acidic and neutralization prior to treatment yields liquid effluents of high ionic strength. The interfering effects of an excess of chloride, sulfate and nitrate ions on metal accumulation by a Citrobacter sp. were investigated. Sulfate ion (300 mM) did not interfere with metal accumulation although 15–20% of the activity was lost in the presence of nitrate ion. This was attributable to an effect on the phosphatase enzyme responsible for metal uptake. Chloride ion interfered with uranyl ion uptake by cells immobilized in a flow‐through bioreactor but had little effect on metal accumulation by batch cell suspensions. These results have implications for the choice of bioreactor design for bioprocess use.