Abstract: A composite bioreactor and a method of using same is described. The bioreactor (10) comprises a combination of a sulfur oxidizing bacteria (SOB) bioreactor (12) directly on top of a sulphate reducing bacteria (SRB) bioreactor (14); the SOB bioreactor (12) comprising a heap of said soil to be rernediated and having suitable microorganisms therein to react with degrade contained contaminants; said SRB bioreactor comprising trough means (18) having support means to support said soil heap associated with an opening thereof, said support means having permeable membrane (16) associated therewith to allow passage of liquid but substantially no soil and sulfur reducing bacteria within said trough means (18); and liquid and nutrient supply means to promote growth of said sulfur oxidizing bacteria and said sulphate reducing bacteria within said composite bioreactor.

Abstract: A process for the decontamination of a medium comprising a particulate material contaminated with one or more metal species, the process comprising the steps of treating a body of the said medium with microbially produced sulfuric acid so as to solubilize the metal species as a metal sulfate; treating the leached metal sulfate by a bioprecipitation process which converts the said sulfate to an insoluble sulfide; separating hydrogen sulfide produced during the bioprecipitation from the insoluble metal sulfide; and oxidizing the separated hydrogen sulfide to form a reusable source of a sulfur-containing ingredient.

Abstract: A process for the decontamination of a medium including a particulate material contaminated with one or more organic species and one or more metal species, the process including the steps of: (1) treating said medium by breaking down the organic species by or through the action of microbial agents, (2) treating the medium with microbially produced sulfuric acid so as to solubilize and leach the metal species as a metal sulfate, (3) treating the leached metal sulfate by a bioprecipitation process which converts the said sulfate into one or more insoluble metal sulfides and hydrogen sulfide, (4) separating the hydrogen sulfide from the one or more insoluble metal sulfides and (5) oxidizing the separated hydrogen sulfide to form a reusable source of a sulfur-containing ingredient.

Abstract: A method for the decontamination of a cementitious or a metallic surface having contaminants is described. The method comprises the steps of supplying to said surface at least one microorganism under conditions conducive to growth of said at least one microorganism; maintaining said conditions conducive to growth of said microorganism and the generation of an acid or other metabolite to degrade said surface to a desired depth; terminating said conditions conducive to growth upon achieving at least said desired depth of degradation; removing the products of said degradation; treating said degradation products; and, disposing of said treated degradation products wherein the at least one microorganism is a citric acid generating microorganism.

Abstract: A biosensor for detecting metal ions of elements such as Hg, Cr, As, Tc, Cu, Ag, Se, V, Mo and U which are capable of being reduced to metal by a reductase enzyme. The reductase enzyme is contained in an immobilized enzyme composition also including a cofactor and a coenzyme. The cofactor, for example NADPH, is oxidized by a reaction coupled with the reductase reduction of the metal ions and the cofactor in its oxidized state, e.g., NADP.sup.+, is re-reduced thereby maintaining a supply of the reduced state cofactor by action of the coenzyme in a further oxidation reaction coupled with the cofactor reduction. The further oxidation reaction may be oxidation of an alcohol to an aldehyde brought about by a dehydrogenase coenzyme. The oxidation brought about by the coenzyme, i.e., the amount of oxidized product, is a measure of the amount of oxidized state cofactor produced which, in turn, is a measure of the concentration of metal ions being detected.

Abstract: In a process for the production of uranium tetrafluoride (UF.sub.4), uranic oxides, UO.sub.3 and U.sub.3 O.sub.8, are dissolved in dilute sulphuric acid (H.sub.2 SO.sub.4) and hydrofluoric acid (HF) is added to produce a uranyl fluoride-sulphate solution which is electrolytically reduced to uranous fluoride-sulphate complexes from which hydrated uranium tetrafluoride is precipitated by the addition of dilute HF at elevated temperature (preferably above 90.degree. C.). The uranyl fluoride-sulphate solution can alternatively be produced by dissolving uranyl fluoride in H.sub.2 SO.sub.4 or from uranyl sulphate solutions (derived from solvent extraction or ion exchange purification processes) conditioned with HF.