Abstract: A method of biotreating a solid material to remove an undesired compound using a nonstirred surface bioreactor is provided. According to the method the surface of a plurality of coarse substrates is coated with a solid material to be biotreated to form a plurality of coated coarse substrates. The coarse substrates have a particle size greater than about 0.3 cm and the solid material to be biotreated has a particle size less than about 250 .mu.m. A nonstirred surface reactor is then formed by stacking the plurality of coated coarse substrates into a heap or placing the plurality of coated coarse substrates into a tank so that the void volume of the reactor is greater than or equal to about 25%. The reactor is inoculated with a microorganism capable of degrading the undesired compound in the solid material, and the solid material is then biotreated in the surface bioreactor until the undesired compound in the solid material is degraded to a desired concentration.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.

Abstract: According to the process, a heap preferably having dimensions of at least 2.5 m high and 5 m wide is constructed with chalcopyrite bearing ore. The constructed heap includes exposed sulfide mineral particles at least 25 weight % of which are chalcopyrite. The concentration of the exposed sulfide mineral particles in the heap is such that the heap includes at least 10 Kg of exposed sulfide sulfur per tonne of solids in the heap. Furthermore, at least 50% of the total copper in the heap is in the form of chalcopyrite. A substantial portion of the heap is then heated to a temperature of at least 50.degree. C. The heap is inoculated, with a culture including at least one strain of thermophilic microorganisms capable of bioleaching sulfide minerals at a temperature above 50.degree. C. A process leach solution that includes sulfuric acid and ferric iron is applied to the heap.

Abstract: A method of biooxidizing sulfide minerals in a nonstirred bioreactor is provided. According to the disclosed method, a concentrate of sulfide minerals is coated onto a plurality of substrates, such as coarse ore particles, lava rock, gravel or rock containing a small amount of mineral carbonate as a source of CO.sub.2 for the biooxidizing bacteria. After the sulfide minerals are coated or spread onto the plurality of substrates, a heap is formed with the coated substrates or the coated substrates are placed within a tank. The sulfide minerals on the surface of the plurality of coated substrates are then biooxidized to liberate the metal value of interest. Depending on the particular ore deposit being mined, the sulfide mineral concentrates used in the process may comprise sulfide concentrates from precious metal bearing refractory sulfide ores or they may comprise sulfide concentrates from metal sulfide type ores, such as chalcopyrite, pyrite or sphalorite.

Abstract: A method for improving bacteria and reagent actions on mineral-bearing particles. In the heap leaching process, the method also increases percolation of the leach solution through the heaped ore without the use of high concentrations of cement, high concentrations of high molecular weight polymers, or high concentration of any other binding agents. The method is accomplished by a process comprising the applying of solutions of varying combinations of bacteria, bacterial nutrients, or leaching reagents, together with surface acting agents onto the ore particles before the ore is formed into a heap. The reagents are applied by spray or foggers or foam into the ore as the ore is mined, transported out of the mine, crushed, or transferred to the heap, and before it is formed into the heap.

Abstract: A metal-containing refractory ore, such as refractory sulfide ore, is split into a first portion and a second portion. The first portion is partially biodigested by a sulfide-digesting microorganism in a biooxidation reactor where the microorganism is acclimated to the sulfide "diet" provided by the ore. The partially digested ore is then combined with the second portion. The resulting material is then dewatered, agglomerated, biooxidized and subjected to a lixiviation process.

Abstract: A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution is provided.

Abstract: A method of biooxidizing sulfide minerals in a nonstirred bioreactor is provided. According to the disclosed method, a concentrate of sulfide minerals is coated onto a substrate, such as coarse ore particles, lava rock, gravel or rock containing mineral carbonate as a source of CO.sub.2 for the biooxidizing bacteria. After the sulfide minerals are coated onto the substrate, a heap is formed with the coated substrates or the coated substrates are placed within a tank. The sulfide minerals are then biooxidized to liberate the metal value of interest. Depending on the particular ore deposit being mined, the sulfide mineral concentrates used in the process may comprise sulfide concentrates from precious metal bearing refractory sulfide ores or they may comprise sulfide concentrates from metal sulfide type ores, such as chalcopyrite, millerite or sphalorite.

Abstract: The subject invention provides a novel process and bioreactor for enhancing the bioleaching of metals from sulfide mineral concentrations.

Abstract: A process is provided for removing hydrogen sulfide out of gas, such as gas separated from geothermal brine, by passing the hydrogen sulfide containing gas and oxygen containing gas through a bioreactor containing bacteria, such as Beggiatoa, Thiothrix and Thiobacilli, supported on a support so that the bacteria oxide the hydrogen sulfide into elemental sulfur, which is subsequently oxidized into sulfuric acid. The flow of the gases through the bioreactor is cyclically reserved about every 12 hours to about 5 days so as to provide a better sulfur distribution in the support, resulting in more efficient oxidation of the elemental sulfur into sulfuric acid. Hydrogen sulfide depleted gas and sulfuric acid are discharged from the bioreactor. A plurality of bioreactors may be used, connected in series or in parallel.

Abstract: Liquid chemical compositions are disclosed for anaerobic biodegradation, detoxification, and transformation of toxic organic and inorganic compounds in a contaminated geologic media under reducing conditions, including, but not limited to, denitrifying, manganese-reducing, iron-reducing and sulfate-reducing conditions. One such liquid chemical composition includes sodium nitrate in the range of one-fifth (0.2) to four (4) pounds per gallon of the chemical composition; sodium hexametaphosphate or other biologically hydrolyzable ring or linear polyphosphate in the range of one twentieth (0.05) to five (5) pounds per gallon of the chemical composition; a surfactant in the range of 0.01% to 10% by volume of the chemical composition; and a diluent in the form of water. A method is disclosed for anaerobic biodegradation, detoxification, and transformation of toxic organic and inorganic compounds in a contaminated geologic media.

Abstract: A process for biologically enhancing an iron-based redox process for catalytic oxidation of a sulfide compound such as hydrogen sulfide from a gas in a redox system wherein said catalyst comprises a ferric compound and at least one organic chelant capable of holding ferric and ferrous ions in solution at processing temperatures and conditions suitable for generation and retrieval of elemental sulfur, comprising the steps of oxidation of a sulfide compound by a gas with a redox system comprising ferric ions, removal of elemental sulfur from said system, and reoxidation of ferrous ions in the redox system in the presence of a culture of bacteria comprising Thiobacillus ferrooxidans and leptospirillium ferrooxidans at a pH at least as high as about 7.5.

Abstract: A process for treating gold bearing sulphide minerals wherein the minerals are subjected to biological oxidation, the product thereof is separated into light and heavy fractions and gold is recovered from the light fraction using a non-biological process.

Abstract: The present invention provides a method for remediating soil contaminated with Cr(VI) by reducing the Cr(VI) to Cr(III) in the soil. The method involves contacting the contaminated soil with a plant that accomplishes the reduction. Removal of the plant from the environment is not required; in fact, preferred embodiments of the invention involve plowing the plant back into the soil environment and replanting the soil.

Abstract: A method and apparatus for anaerobic oxidation of metal sulfides in ores and concentrates. Base-metal and precious-metal ores and concentrates often contain metal sulfides, such iron sulfides (e.g., pyrite, pyrhotite, arsenopyrite, etc.), copper sulfides (e.g., chalcopyrite, chalcocite, etc.), zinc sulfides (e.g., sphalerite, etc.) and/or lead sulfides (e.g., galena, etc.) and/or other metal sulfides), that must be oxidized in order to recover metal values (e.g., gold, silver, or platinum group elements) from the ores. In the present invention, these metal sulfides are oxidized in one reactor under anaerobic or anoxic conditions using oxidized metal ions, such as ferrous ions (Fe.sup.+3), as the oxidizing agent. Anaerobic oxidation of elemental sulfur that is produced by metal sulfide oxidation is biocatalyzed by sulfur-oxidizing bacteria, such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans, or or Sulfolobus sp.

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: Chelants represented by Formula 1b: ##STR1## are determined to be biodegradable when Distance A is from about 3.8.times.10.sup.-10 to about 4.6.times.10.sup.-10 m, Distance B is from about 5.1.times.10.sup.-10 to about 5.9.times.10.sup.-10 m, and Distance C is from about 4.3 to about 6.7.times.10.sup.-10 m). Compounds meeting these criteria are referred to as compounds of Formula 2.

Abstract: The invention relates to Proteobacteria that show unusually high level resistance to a wide range of metal oxides and oxyanions and to methods using selected Proteobacteria subgroups for efficient reduction of certain metal oxides and oxyanions to the free metal. High level resistance was shown to be affected by growth conditions, and was observed in facultative photoheterotrophs such as Rhodobacter sphaeroides grown either chemoheterotrophically or photoheterotrophically. The disclosed methods are adaptable to the production of hydrogen from cultures of Peoteobacteria grown in the presence of tellurite class oxyanions with carbon dioxide and nitrogen as carbon and nitrogen sources. The methods have commercial application for efficient bioremediation of carbon dioxide and nitrogen.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometullurgically treating the bioleached ore to recover the precious metal values. If sufficient quantity of precious metal values are contained in the separated clays and fines, these materials can be further processed to recover the precious metal values contained therein.

Abstract: A method for recovering precious metals from carbonaceous ore comprising leaching the ore with a lixiviant solution and then preg-robbingly concentrating the precious metal-lixiviant complexes in solution on to the native carbonaceous component of the ore for subsequent recovery. The preg-robbing capacity of the native carbonaceous component of the ore can be augmented by adding recycled carbonaceous matter or finely ground carbon to the ore-lixiviant mixture.

Abstract: Methods and apparatus for the hydrometallurgical separation and recovery of biological nutrients, cadmium, lead, and gypsum from raw materials such as electric arc furnace flue dust. Biological nutrients, including zinc and iron, are selectively separated and recovered from raw materials, including metals and metal oxides, and are selectively and variably recombined, to achieve a biological nutrient product which a desired relative concentration of zinc and iron. The process is a closed system generating no solid waste, no liquid water or acid waste streams, and whereby gypsum, and substantially all hazardous wastes such as lead and cadmium, are separated and recovered from raw material for sale as commercial products.

Abstract: A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution is provided.

Abstract: A method of biotreating a solid material to remove an undesired compound using a nonstirred surface bioreactor is provided. According to the method the surface of a plurality of coarse substrates is coated with a solid material to be biotreated to form a plurality of coated coarse substrates. The coarse substrates have a particle size greater than about 0.3 cm and the solid material to be biotreated has a particle size less than about 250 .mu.m. A nonstirred surface reactor is then formed by stacking the plurality of coated coarse substrates into a heap or placing the plurality of coated coarse substrates into a tank so that the void volume of the reactor is greater than or equal to about 25%. The reactor is inoculated with a microorganism capable of degrading the undesired compound in the solid material, and the solid material is then biotreated in the surface bioreactor until the undesired compound in the solid material is degraded to a desired concentration.

Abstract: The present invention relates to a process for bio-oxidating insoluble mineral compounds from ores comprising the steps of:a) conditioning the ore with an acidic solution;b) adding a microbial inoculum to the conditioned ore;c) drying the ore until soluble bio-oxidized products in solid state are obtained, the solid products containing microbial colonies;d) maintaining the ore into an adequate range of temperature for the employed microorganism, until the bio-oxidation is completed; ande) separating out the soluble bio-oxidized products in solid state by washing or by another suitable method.

Abstract: A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution is provided.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.

Abstract: A method and apparatus for extraction of precious metals from their ores and the product thereof. Oxidized ore comprising a precious metal is exposed to a leaching solution (lixiviant) comprising a relatively high concentration (fugacity) of dissolved hydrogen sulfide gas, a relatively high concentration (activity) of bisulfide ions, and a relatively low concentration (fugacity) of dissolved hydrogen gas. The hydrogen sulfide gas and bisulfide ions are preferably added to the solution by sulfate-reducing bacteria growing in a medium comprising dissolved sulfate ions and dissolved nitrate ions, but abiotic sources may also be used. Examples of such bacteria include mesophilic, fresh-water species such as Desulfobacterium catecholicum DSM 3882 and Desulfovibrio simplex DSM 4141; mesophilic, salt-water species such as Desulfovibrio salexigens DSM 2638; and thermophilic, fresh-water species such as Desulfomaculum kuznetsovii VKM B-1805. The complexed precious metal is recovered from the lixiviant.

Abstract: A method for recovering precious metals from carbonaceous ore comprising leaching the ore with a lixiviant solution and then preg-robbingly concentrating the precious metal-lixiviant complexes in solution on to the native carbonaceous component of the ore for subsequent recovery. The preg-robbing capacity of the native carbonaceous component of the ore can be augmented by adding recycled carbonaceous matter or finely ground carbon to the ore-lixiviant mixture. Furthermore, after the carbonaceous component of the ore is separated from the gangue, the gangue material can be treated in a hot CIL process to further increase the recovery of the precious metal.

Abstract: A bioleaching method is provided for recovering nickel from an ore selected from the group consisting nickel-containing lateritic ores and nickel-containing sulfidic ores or concentrates thereof. Where the ore selected is a nickel-containing lateritic ore, at least one micro-organism selective to the leaching of the lateritic ore is provided as an aqueous solution thereof maintained at a pH ranging from about 1 to 3 including a nutrient for the micro-organism. The ore may be in the form of a heap, or a charge in a vat, or as a slurry. Where the ore selected is a nickel-containing sulfidic ore or concentrate thereof, at least one micro-organism comprising a biooxidizing bacterium selective to the leaching of sulfidic ore is added as an aqueous solution to the sulfidic ore or concentrate maintained at a pH of about 1 to 3, including a nutrient for the bacterium.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometullurgically treating the bioleached ore to recover the precious metal values. If sufficient quantity of precious metal values are contained in the separated clays and fines, these materials can be further processed to recover the precious metal values contained therein.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.

Abstract: In the removal of hydrogen sulfide from a gas stream by use of a liquid catalyst containing ferric ions, the ferric ions of the liquid catalyst are converted to ferrous ions. Regeneration of the ferric ions can be accomplished by bubbling air through the liquid catalyst. A significant decrease in regeneration time for transforming the ferrous ions back to the original ferric ion state can occur when a culture of Thiobacillus ferrooxidans bacteria is introduced to the liquid catalyst. Optimization indicates a pH range between 6.0 and 9.0, a temperature between 20.degree. C. and 45.degree. C. and a cell concentration of 12.5.times.10.sup.8 cells per liter.

Abstract: Process for biolixiviating minerals from copper sulfides and also from their flotation concentrates, characterized by the use of biolixiviation through indirect contact as well as separation and improvement of the chemical and biological steps of the biolixiviation process. In the chemical step, a low concentration of ferric sulfate is used as the lixiviating agent. In the biological step, bacterial films of Thiobacillus ferrooxidans attached to an inert solid are used to regenerate the lixiviating agent by converting the ferrous ion into ferric ion through oxidation. The regenerated agent is then recycled to the lixiviation reactor. The biolixiviation process permits complete extraction of the copper contained in the ore and results in a lixiviation liquor which contains all the copper charge and a low concentration of ferric sulfate similar to the low concentration of ferric sulfate used initially.

Abstract: A biohydrometallurgical apparatus and method for extracting precious metals, including gold and silver, from oxidized ore by means of leaching with a neutral bisulfide solution instead of cyanide, thiourea, thiosulfate, or other conventional lixiviants is disclosed. In a preferred embodiment, a first process step of conventional bio-oxidation of ore particles is accomplished to free precious metals dispersed or occluded within the ore. A portion of the acidic, base-metal sulfate leach solution produced by bio-oxidation is introduced to an anaerobic reactor. In a heap leach embodiment of the process, the anaerobic reactor is a side-stream reactor. In an alternative slurry (e.g.,vat) leaching embodiment, the anaerobic process may occur on-line. A preferably non-toxic electron donor, such as acetate or methanol (which does not bind effectively to activated carbon), is added to the anaerobic reactor to enrich within it a mixed culture of sulfate-reducing bacteria.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometullurgically treating the bioleached ore to recover the precious metal values. If sufficient quantity of precious metal values are contained in the separated clays and fines, these materials can be further processed to recover the precious metal values contained therein.

Abstract: A process for recovering precious or base metals from particulate refractory sulfide materials comprises: a) contacting the sulfide material with an aqueous solution containing a thermotolerant bacteria culture capable of promoting oxidation of the sulfide material at a temperature in the range from 25.degree. to 55.degree. C., b) separating the oxidized residue from the aqueous liquid, and, c) treating the oxidized residue and/or the aqueous liquid to recover metal. In this context, a thermotolerant bacterium is one which has an optimum growth temperature of 40.degree. to 45.degree. C., and an operating temperature of 25.degree. to 55.degree. C.

Abstract: Materials and methods for the enhancement of the biooxidative acid leaching of heavy metals from sulfide ore are disclosed and claimed. The enhancement of bioleach solutions with a nutrient supplement selective for a particular sulfide oxidizing strain of bacteria significantly increases copper solubilization of chalcopyrite ore. Likewise, copper solubilization is enhanced by enriching bioleach solutions with a non-selective growth mediums.

Abstract: A variety of processes for recovering gold from gold ore are disclosed. Briefly, the methods include culturing at least one microorganism species capable of producing cyanide ion under conditions wherein the microorganism produces cyanide ion, thus forming a cyanide ion-containing culture; contacting the cyanide ion-containing culture with gold ore, causing production of gold ion-cyanide ion complexes and biosorption of said complexes to said cultures; and recovering gold from the culture. The invention may be practiced with a variety of microorganisms, including Chromobacterium violaceum and Chlorella vulgaris.

Abstract: A process for the removal of sulphur compounds from a gaseous effluent, comprising the steps of: a) contacting the gaseous effluent with an aqueous solution wherein sulphur compounds are dissolved; b) adjusting the concentration of buffering compounds such as carbonate and/or bicarbonate and/or phosphate in the aqueous solution to a value between 20 and 2000 meq/l; c) subjecting the aqueous solution containing sulphide to sulphide-oxidizing bacteria in the presence of oxygen in a reactor wherein sulphide is oxidized to elemental sulphur; d) separating elemental sulphur from the aqueous solution; and e) recycling the aqueous solution to step a). This process is suitable for removing H.sub.2 S from biogas, ventilation air etc. It can be used for removing SO.sub.2 from combustion gases by introducing the additional step, after step a) and before step c), of subjecting the aqueous solution containing the sulphur compounds to a reduction of the sulphur compounds to sulphide. H.sub.2 S and SO.sub.

Abstract: A hydrometallurgical process for the recovery of one or more metal values from a metal ore material in the presence of clays and/or fines material, said ore material being comprised of one or more metal values and a matrix material having a sulfur content wherein the sulfur is present in an oxidation-reduction state of zero or less. The process comprises forming particulates from particles of said ore material, particles comprising said clays and/or fines material, an acid-resistant polymeric agglomeration aid and an inoculate comprising bacteria capable of at least partially oxidizing the sulfur content; forming a heap of said particulates; biooxidizing the sulfur content and recovering those one or more metal values.

Abstract: A variety of processes for recovering gold from gold ore are disclosed. Briefly, the methods include culturing at least one microorganism species capable of producing cyanide ion under conditions wherein the microorganism produces cyanide ion, thus forming a cyanide ion-containing culture; contacting the cyanide ion-containing culture with gold ore, causing production of gold ion-cyanide ion complexes and biosorption of said complexes to said cultures; and recovering gold from the culture. The invention may be practiced with a variety of microorganisms, including Chromobacterium violaceum and Chlorella vuloaris.

Abstract: A process for treating optionally oxidized sulphidic material containing one or more heavy metals, by aerobic microbial oxidation of the optionally oxidized sulphidic material in an aqueous suspension using a sulphur oxidizing micro-organism to convert optionally oxidized sulphide into soluble sulphate at a pH sufficient to maintain most of the heavy metals present in a soluble form. A preferred sulphidic material is sulphidic waste, preferably sulphidic slag. The formed sulphate is environmentally less harmful than the sulphide, while the heavy metals compounds are suitable for recovery of the metals using known methods.

Abstract: A method of releasing metals from catalysts in a form that is readily recoverable using denitrifying bacteria is disclosed. The method can be used to regenerate catalysts and to recover metals from catalysts, especially molybdenum and nickel.

Abstract: Disclosed is an efficient biological process for recovering heavy metals from refractory ore, and a process for removing heavy metal contaminants from the soil. The process utilizes a potato extract growth medium (PEGM) to greatly increase the efficiency for recovering heavy metals from ores and for removing heavy metal contaminants from soil. Microbes which can be used in the process are manganese reducing Bacillus sp., or mutants thereof which retain the metal recovering properties of the parent microbe. Further, recombinant microbes, as disclosed herein, can be used in the same manner as the native microbe.

Abstract: A method is provided for the recovery of precious metal values, such as gold and silver, from refractory carbonaceous, or carbonaceous-sulfidic ore material. The ore material is inoculated using a specific microbial consortium and then incubated to deactivate the carbonaceous component of the material to prevent binding of the precious metal values to the carbonaceous component. The precious metal is then recovered.

Abstract: A continuous process for the microbiological conversion and removal of malodorous sulphur-containing organic and inorganic compounds from a gaseous stream, comprising the steps of providing a column filled with packing material. Passing a biologically active liquid stream containing nutrients and a consortia of bacteria including microorganisms of the Thiobacillaceae family through the column whereby the bacteria are immobilized onto all available surface area of the packing material. Maintaining the temperature conditions within the column between about 5.degree. C. to about 47.degree. C. and the pH conditions between about 5 to about 9. Concurrently passing a gaseous stream containing the malodorous sulphur-containing organic and inorganic compounds through the column at a liquid gas ratio of about 3:7 for a sufficient period of time to allow the bacteria to convert greater than about 97% of the sulphur compounds within the gaseous stream into a useful form of elemental sulphur.

Abstract: In a process for the biological elimination of halogen- and sulfur-containing gaseous pollutants from a waste air stream, the waste air stream is passed through an intermittently moistened trickling filter tower. In a preferred variant of the process, individual sections of the surface of the trickling filter are subjected to intermittent phase-displaced moistening. Cyclic moistening of the trickling filter sections can be achieved in this way. The volume-time yield in the biological purification of gas streams can be considerably improved by this process.

Abstract: A reactor vessel for use in treating slurries containing minerals, soils or sludges contaminated with toxic organic substances is disclosed. The vessel includes a tank, having a sealed cover, a mixer arrangement, an air supply arrangement and an exhaust gas recycling system. The air supply arrangement includes one or more porous, flexible membrane diffusers adapted for introducing gas, in the form of fine bubbles, into a tank-contained slurry.

Abstract: Remediation of toxic waste materials in solid, liquid or a mixture of solid and liquid form provides rapid reduction of the toxic conditions to innocuous levels. The process utilizes indigenous microorganisms present in the waste materials. The process comprises contact mixing waste materials with protein nutrients in water, air entraining the waste materials and protein nutrients during mixing to form a bioactive structure, and exposing the bioactive structure to cure in air until the toxic materials are remediated to a predetermined innocuous level.

Abstract: A variety of processes for recovering gold from gold ore are disclosed. Briefly, the methods include culturing at least one microorganism species capable of producing cyanide ion under conditions wherein the microorganism produces cyanide ion, thus forming a cyanide ion-containing culture; contacting the cyanide ion-containing culture with gold ore, causing production of gold ion-cyanide ion complexes and biosorption of said complexes to said cultures; and recovering gold from the culture. The invention may be practiced with a variety of microorganisms, including Chromobacterium violaceum and Chlorella vulgaris.