Abstract: The present invention is a process for oxidation of a liquid which contains cyanide and soluble metal ions, using an oxygen-containing gas. Art example of such a liquid is the liquid waste produced during metal treatment processes. The disclosed process not only eliminates the cyanide completely, but also converts the metal dissolved in the liquid into granular metal oxides which can be readily recovered.

Abstract: Hexavalent chromium is reduced to trivalent chromium by reacting the hexavalent chromium with peroxide in acidic solution. In another aspect of the invention, the hexavalent chromium reduction with peroxide step may take place after the step of the destruction with aldehyde of any cyanide or cyanide compounds present, so that the peroxide may destroy any excess aldehyde remaining after the first step. No materials are added which have to be removed later in the process. In either case, the waste solution may then be treated with sodium hydroxide, or other conventional materials, to precipitate chromium hydroxide and effect removal of the hazardous chromium from the waste stream.

Abstract: An in situ method of cleaning soil and/or water contaminated with a contaminant comprising one or more compounds selected from the group consisting of metal compounds, sulfur compounds and cyanide compounds comprises breaking up contaminated soil, admixing soil with water and a biodegradable detergent in a proportion effective to obtain an aqueous slurry where the soil, any contaminant and the detergent interact to form contaminant-detergent formations, allowing the slurry to stand under conditions effective to permit any contaminant-detergent formations to rise in the aqueous slurry, separating the contaminant-detergent formations from the aqueous slurry now comprising partially decontaminated soil and water, separating the soil from the water, repeating the cleaning and separation steps until the soil has less contaminant than a predetermined value, typically a 80-90% decrease, admixing the soil having a lower contamination level with water and an activating agent for microorganisms capable of removing the

Abstract: Cyanide present in aqueous streams, such as effluents from electroplating and gold mining operations is reduced or eliminated by contacting the cyanide-containing stream with oxygen and carbon dioxide in the presence of ferrous ions, nickelous ions or cobaltous ions. The oxygen may be provided by air or oxygen and the contacting is carried out until the pH of the aqueous stream is reduced to a value in the range of about 6 to 8 and preferably 6.5 to 7.5.

Abstract: The oxidation of cyanide under acid conditions using oxygen as the oxidizing agent can be effected under mild reaction conditions when certain metal chelates are used as catalysts. Especially effective chelates are metal phthalocyanines, particularly where the metal is vanadium or a member of the iron group metals. The oxidation can be effected homogeneously using water soluble metal chelates, or can be performed heterogeneously, especially in a continuous fashion using a packed bed reactor, by using suitable water-insoluble metal chelates, especially when supported on appropriate carriers.

Abstract: A process is provided for removing ammoniacal values of potential environmental concern, both present and latent, from cyanate-containing waste streams and water-wet waste solids, typically generated in gold leaching or electroplating operations. The process includes heating the waste material to a temperature in excess of 50.degree. C. to convert ammonium cyanate to urea and optionally reducing pH to a range of 2.5 to 5 to accelerate hydrolysis of cyanate to ammonium carbonate, to supply ammonium ions for reacting with unhydrolyzed cyanate.

Abstract: A system and process are provided for treatment of cyanide-containing waste to form a substantially detoxified reaction product. The system comprises a reaction vessel, a heat exchange conduit extending through the reaction vessel to provide a flow path for heat exchange fluid, a heating loop for circulating heat exchange fluid through the heat exchange conduit at a temperature sufficient to initiate hydrolysis of cyanides in cyanide-containing waste to form the substantially detoxified reaction product, a cooling loop for circulating heat exchange fluid through the heat exchange conduit at a temperature sufficient to cool the substantially detoxified reaction product to a discharge temperature, and an apparatus for diverting flow of heat exchange fluid from the heating loop to the cooling loop.

Abstract: A method is disclosed for detoxifying an aqueous waste solution containing cyanide. The method involves adding a source of silicon oxide to the cyanide containing aqueous waste solution in a concentration of 0.001 to 10 g silicon dioxide/liter aqueous waste solution, at an alkaline pH and a temperature of from 10.degree. to 100.degree. C. Hydrogen peroxide or another peroxygen compound is added in a sufficient quantity to convert the aqueous waste solution containing cyanide to an aqueous solution containing environmentally less toxic materials.

Abstract: The oxidation of complexed cyanide using oxygen as the oxidizing agent when certain metal chelates are used as catalysts may be enhanced by irradiating the complexed cyanide with ultraviolet light prior to or concurrent with the oxidation. Especially effective chelates are metal phthalocyanines, particularly where the metal is vanadium or a member of the iron group metals. The oxidation can be effected homogeneously using water soluble metal chelates, or can be performed heterogeneously, especially in a continuous fashion using a packed bed reactor, by using suitable water-insoluble metal chelates, especially when supported on appropriate carriers.

Abstract: Aqueous solutions which are contaminated by hydrogen sulfide, hydrogen cyanide, and ammonia are brought to a pH of about 3 or less after their formation and treated with an inert gas in a stripping column to remove the sulfide and cyanide. The pH of the solution is then increased to about 10 or more and the solution is again treated with an inert gas in a second stripping column to remove the ammonia.

Abstract: A method for detoxifying cyanide waste using a reactive sugar having aldose functionality is provided. The reactive sugar is mixed with the cyanide waste to produce sugar acid, a non-toxic and environmentally safe compound.

Abstract: A process is disclosed for the detoxification of aqueous solutions containing cyanides and/or cyano complexes in the presence of heavy metals which are Mn, Co, Ni, Cu, Cd and Zn, more particularly Cu, by oxidative treatment of the solutions with peroxide compounds at pH values of 8 to 12. Peroxide compounds from the group consisting of alkali metal percarbonates and alkaline earth metal peroxides are used. The peroxide compounds are added to the solutions to be detoxified per se or are formed in situ therein from hydrogen peroxide and other components. Sodium perborate, sodium percarbonate and calcium peroxide are preferred.

Abstract: A process is disclosed for the detoxication of aqueous solutions which contain cyanohydrins, in particular glycol nitrile, and/or nitriles and in addition contain decomposition catalyst for peroxide compounds, in particular manganese compounds, by perhydrolysis of the cyano compounds at temperatures of from 5.degree. to 80.degree. C. and pH values of from 8 to 12 by means of one or more peroxide compounds which are alkali metal percarbonates and perborates of alkali metals and alkaline earth metals and alkaline earth metal peroxides. The peroxide compounds are added as such to the solution to be detoxified or formed in situ in the solution to be detoxified. Sodium percarbonate is preferably used.

Abstract: A process is disclosed which limits the corrosion of the materials of construction of a wet oxidation system treating wastewaters. The process is particularly useful in the wet oxidation treatment of ammonium sulfate containing wastes such as acrylonitrile wastewaters. The wastewater is mixed with an oxygen containing gas such that a substantial residual oxygen gas concentration is maintained from before the stream-gas mixture is heated for wet oxidation until after the oxidized stream-gas mixture is cooled and separated. Preferably, in the treatment of acrylonitrile waste water the shutdown procedure comprises cooling said waste stream by introducing an aqueous liquid substantially free of organic impurities and containing a basic material.

Abstract: This invention pertains to a method of treating cyanide contained in wastewater with particularly high levels of solids in the stream. The process involves either simultaneous or step-wise dosage of hydrogen peroxide in the form of an aqueous solution of a concentration between 35% to 90% by weight, preferably at least 50% by weight, and SO.sub.2 either in the form of gaseous SO.sub.2 or solution of sodium and/or potassium sulfite or metabisulfite resulting in the conversion of cyanide ions to non-toxic cyanate ions.

Abstract: A method for reducing the concentration of target co-ions in a liquid feed mixture comprising target co-ions and counter-ions by adding a colloid such as a polyelectrolyte or surfactant comprising a colloidal ion and colloidal counter-ions to the feed mixture wherein the colloidal ion has the same type of charge as the target co-ion. The feed mixture containing the colloid is filtered through an ultrafiltration membrane having pores small enough to block the passage of the colloidal ion.

Abstract: Biological treatment process removes free and metal complexed cyanides, and thiocyanate through oxidations. Even high concentrations of these pollutants are workable. Toxic heavy metals are absorbed and adsorbed within a biofilm. This process has been adapted to and performs well at high cyanide concentrations (e.g., even above about 100 mg/L and high pH (e.g., even higher than about 9.5). Mixed cultures of adapted strains of Pseudomonas are utilized to perform biological oxidation within the system. End products of oxidation include carbonates, sulfates, and nitrates. The pH is neutralized by metabolism of, or by, intermediate reaction products. The biological processes can be utilized as a pretreatment or post-treatment process in conjunction with chemical processes.

Abstract: The invention provides an apparatus for continuous thermal hydrolysis of cyanide ions and cyanide-containing ions contained in a liquid, comprising an elongated tubular reactor of a size selected to enable the liquid to be retained in the reactor for a predetermined reaction time, a conduit for supplying the liquid to the reactor, means for adding a base to the liquid prior to heating, and means, associated with the conduit, for instantaneously and uniformly heating the liquid to a preselected temperature. The apparatus preferably uses high pressure steam to heat the liquid and appears much less subject to fouling by scale.

Abstract: A process for removing cyanide anions from waste waters using halogen-free ferric salts is disclosed. The process is particularly effective when treatment of cyanide waste waters is done by adding ferric sulfate while adjusting pH of the waste waters with a halogen-free acid, such as sulfuric acid, to a pH ranging from about 3.0 to 5.0.The ferric ferricyanides formed are agglomerated and flocculated using synthetic polymers along with whatever other dispersed or suspended solids may be present in the waste waters, and this dense sludge is separated in a clarifier. Cyanide removal is at least 80%, relative to initial cyanide concentrations, and preferably 90% removal or higher.Cyanide wastes from coke oven off gas scrubbing waters are particularly waste waters amenable to this treatment.

Abstract: A method of removing undesired ions, such as chlorine, hypochlorite, chromium, cyanide and heavy metal ions, from an aqueous preparation containing one or more of said ions consists of adding to the aqueous preparation an effective amount of magnesium bisulfite to inactivate the undesired ions and then adjusting the pH of the mixture to an appropriate pH. Compositions containing magnesium bisulfite and divalent and trivalent ions are disclosed.

Abstract: A process for chemically modifying at least one contaminant component in an aqueous-based material comprising: contacting at least one contaminant component in an aqueous-based material with at least one metal component selected from the group consisting of vanadium components in which vanadium is present in the 5+ oxidation state in an amount effective to promote the chemical modification of the at least one contaminant component in the aqueous-based material, iron components in which iron is present in the 3+ oxidation state in an amount effective to promote the chemical modification of the at least one contaminant component in the aqueous-based material, manganese components in which manganese is present in the 3+ oxidation state in an amount effective to promote the chemical modification of the at least one contaminant component in said aqueous-based material and mixtures thereof, and at least one oxygen transfer agent in an amount effective to do at least one of the following: maintain at least partially

Abstract: A process is provided for detoxifying an aqueous solution containing weak acid-dissociable cyanide metal complexes. The process comprises incorporating hydrogen peroxide and at least 1 mole of citric acid per mole of complexed metal ion and maintaining the pH of the solution between 8 and 12.

Abstract: A process for treatment of waste aqueous process streams from industrial process containing both cyanide ions and dissolved ammonia to reduce the cyanide content, comprising the consecutive steps: (a) adding a halogenating agent to the solution while maintaining the pH of the solution at greater then 7; (b) removing ammonia from the solution by aeration; (c) acidifying the solution to a pH of less then 7; (d) substantially neutralizing the solution; and (e) removing the ammonia from the solution by aeration.

Abstract: The oxidation of cyanide using oxygen as the oxidizing agent can be effected under mild reaction conditions when certain metal chelates are used as catalysts. Especially effective chelates are metal phthalocyanines, particularly where the metal is vanadium or a member of the iron group metals. The oxidation can be effected homogeneously using water soluble metal chelates, or can be performed heterogeneously, especially in a continuous fashion using a packed bed reactor, by using suitable water-insoluble metal chelates, especially when supported on appropriate carriers.

Abstract: A novel cyanide converting enzyme, a "cyanidase" is described.The enzyme is extremely efficient in reducing substantial concentrations of cyanide to very low levels in a broad pH, and temperature range, and in the presence of organics and metal ions.

Abstract: Cyanide is removed from a cyanide-containing waste water by passing the water through an adsorbent porous solid substrate which has been treated with a water insoluble metal compound, preferably copper sulfide (CuS), that facilitates adsorption of the cyanide, a preferred adsorbent substrate is activated carbon. An oxidizing agent is supplied to the adsorbent to oxidize the adsorbed cyanide, the preferred oxidizing agent is a source of oxygen such as air. Ammonia is passed over the bed along with the waste water to enhance the longevity of the adsorbent.

Abstract: An integrated process for heavy metal and cyanide removal in aqueous waste stream from plating processes wherein cyanide is oxidized by hypochlorite at approximately pH of 11.5 and hexavalent chromium is reduced to trivalent chromium at ambient temperature with ferrous sulfate at pH of 9.5; excess hypochlorite from cyanide destruction reacts with ferrous sulfate and additional ferrous sulfate is added to reduce hexavalent chromium to trivalent chromium to allow hydroxide co-precipitation with hydroxides of the ferric iron and hydroxides of copper, chromium, zinc, cadmium, manganese, etc., which are then separated by settling and filtration.

Abstract: Disclosed is a method for treating in a continuous manner an aqueous solution containing ions of a given type in order to remove these ions from the solution. According to this method, the aqueous solution containing the ions to be removed is first neutralized if it is acidic. Then, it is contacted with a metal salt which is sparingly soluble in water and has a very strong affinity to react with the ions to be removed to form therewith another salt which is insoluble in water, for a period of time sufficient to allow this other salt to be formed and precipitate. This method is very efficient and can be used, by way of example, for removing chromium ions from an industrial waste water, using barium carbonate as sparingly soluble salt.

Abstract: An improved process for removal of soluble contaminants from wastewater is disclosed which provides significantly enhanced contaminant removal and overall process efficiencies. The improved contaminant removal process is especially suitable for treatment of industrial effluents having high levels of dissolved cyanide and arsenic contaminants. Wastewater undergoes multiple stage sludge treatment, wherein sludge is mixed with wastewater sequentially in a plurality of discrete reaction stages for relatively short retention times. Reaction conditions which promote chemical and/or physical reaction of soluble contaminants with sludge are maintained, and liquid/solids separation is effected after each sludge treatment stage. Oxidizing agent is preferably mixed with the wastewater prior to multiple stage sludge treatment to change the oxidation state of inorganic contaminants and remove cyanide contaminants from solution.

Abstract: A system for removing cyanide and related species from a cyanide-containing waste fluid, for example, of the sort generated by mining operations, includes means for generating hydrogen peroxide by the burning of a fuel and the quenching of that burning with the waste fluid. At least a portion of the cyanide content of the waste fluid is eliminated by oxidation with the hydrogen peroxide, and the quenching can also provide organic material to serve as a carbon source for microbes which degrade residual cyanide in the treated waste stream.

Abstract: A method for reducing the amount of anionic metal-ligand complex in a solution comprises: (a) contacting the solution with a substance selected from: a compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion, and w, x, y, z and n satisfy the following: 0.ltoreq. z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x); a calcined product of said compound and mixtures thereof; and (b) separating the substance from the solution. A method for removing substantially all metal-cyanide, -thiocyanate, -thiosulfate, -citrate and/or -EDTA complex from a solution containing one or more of said complexes is also disclosed.

Abstract: Methods are provided for removing contaminants from an aqueous solution to yield a less contaminated aqueous effluent. In one embodiment of the invention, the method comprises coprecipitating non-volatile contaminants (i.e., heavy metals, light metals, cyanide, phenolics, oil and grease, TSS, BOD, COD, and/or TOC) with a carrier precipitate which is formed in situ within the aqueous solution. In another embodiment of the invention, the method comprises partitioning volatile organic contaminants between a liquid phase and a gas phase. In yet a further embodiment, the above versions of the invention are simultaneously performed in the same reaction vessel.

Abstract: A method is disclosed for treating wastewater from a suspension styrene-acrylonitrile (SAN) copolymerization process. The wastewater contains SAN and polyvinyl alocohol (PVA) as a suspensing agent. The method includes the steps of adding to the wastewater a floc forming effective amount of a) a water soluble borate salt, preferably sodium metaborate and b) a water soluble ferrous salt, preferably ferrous sulfate, and separating the resulting floc which contains the SAN particles and PVA from the treated wastewater.

Abstract: Cyanide present in aqueous streams, such as effluents from electroplating and gold mining operations is reduced or elliminated by contacting the cyanide-containing stream with oxygen and carbon dioxide in the presence of cupric ions. The oxygen may be provided by air or oxygen and the contacting is carried out at until the pH of the aqueous stream is reduced to a value in the range of about 6 to 8 and preferably 6.5 to 7.5. Cupric sulfate has been found to be particularly effective for the described reaction.

Abstract: A system for removing cyanide and related species from a cyanide-containing waste fluid, for example, of the sort generated by mining operations, includes means for generating hydrogen peroxide by the burning of a fuel and the quenching of that burning with the waste fluid. At least a portion of the cyanide content of the waste fluid is eliminated by oxidation with the hydrogen peroxide, and the quenching can also provide organic material to serve as a carbon source for microbes which degrade residuel cyanide in the treated waste stream.

Abstract: A process is disclosed for the detoxification of effluents containing cyanide by treating with a mixture of hydrogen peroxide and phosphoric acid.

Abstract: Treatment of effluent containing cayanide is disclosed wherein a mixture of H.sub.2 SO.sub.4 and H.sub.2 O.sub.2 with between 0.01 and 0.5 moles of H.sub.2 SO.sub.4 per mole of H.sub.2 O.sub.2 is used.

Abstract: Recovery of precious metals such as gold and silver from aqueous cyanide solutions thereof, by contact with a reagent containing a guanidine functionality. The guanidine reagent extracts the precious metal from the aqueous solution which is subsequently stripped from the guanidine reagent and recovered by conventional methods. Certain novel guanidine compounds suitable for extracting gold and silver are disclosed.

Abstract: A waste water treatment system for high temperature hydrolysis of cyanides has a reactor operating at a sufficiently high temperature and pressure to effect hydrolysis of cyanide in the waste waters. A heat exchanger system is provided through which reactor effluent and reactor influent streams flow. The improved waste water treatment system includes a first tube in tube heat exchanger for an influent stream and a second tube in tube heat exchanger for an effluent stream. A heat exchange medium is circulated between the effluent heat exchanger and the influent heat exchanger to cool down the effluent and in turn use the heat to heat up the influent to the reactor. The heat exchangers are arranged such that the influent and effluent streams pass through the tube side of each heat exchanger to minimize clogging of the first and second heat exchangers, while at the same time providing for effective heat exchange in cooling the effluent and heating up the waste waters to be treated.

Abstract: A method for reducing the amount of anionic metal-ligand complex in a solution comprises: (a) contacting the solution with a substance selected from: a compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z .multidot.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion, and w, x, y, z and n satisfy the following: 0.ltoreq.z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.3/2x; a calcined product of said compound and mixtures thereof; and (b) separating the substance from the solution. A method for removing substantially all metal-cyanide, -thiocyanate, -thiosulfate, -citrate and/or -EDTA complex from a solution containing one or more of said complexes is also disclosed. The latter method comprises contacting the solution with a sufficient amount of substance consisting essentially of a compound selected from: hydrotalcite, calcined hydrotalcite and mixtures thereof.

Abstract: The process comprises injecting into the inlet of a polyphase tubular reactor (6), on one hand, the aqueous solution at such temperature that the oxidation reaction occurs at a temperature between 50.degree. C. and 370.degree. C. and at an absolute pressure Pe of between 2 bars and 210 bars, and, on the other hand, gaseous oxygen at a pressure slightly higher than said pressure Pe. The invention is applicable to the treatment of effluents for the chemical destruction of pollutants.

Abstract: A process for the removal of cyanide and other impurities from an aqueous solution is disclosed. The process comprises adding copper ion and ferrous ion as reagents to the solution at a pH of about 4 to 8 with a ratio of copper to cyanide in the range of 3:1 to 10:1 by weight and with a ratio of iron to copper of at least 0.3:1 by weight.

Abstract: A process for the treatment of aqueous effluent containing cyanide and toxic or heavy metals, wherein the effluent is contacted with a sufficient amount of hydrogen peroxide to oxidize at least a substantial portion of the cyanide in the effluent in the presence of sufficient trimercaptotriazine to react with a substantial portion of the metal present in said effluent, and precipitating said metal component.

Abstract: A method for operating a continuous wet oxidation system for destroying cyanide in caustic cyanide and metal wastes which scale upon heating. Raw waste is introduced into the wet oxidation reactor without heating while a mixture of heated dilution water and oxygen containing gas is introduced into the reactor by a separate inlet. The reactor is fitted with a pair of valved effluent lines and corresponding valved lines for introducing dilute mineral acid into each effluent line at system pressure. Oxidized effluent and offgases exit through a first effluent line while dilute mineral acid flows through a second effluent line into the reactor to prevent scale buildup. Periodically the flows are alternated such that oxidized effluent and offgases exit through the second effluent line and dilute mineral acid flows through the first effluent line into the reactor to remove scale. The oxidized effluent and offgases are then cooled and separated.

Abstract: A method removing cyanuric acid from bather water in swimming pools, spas, and the like. Melamine is added to the bather water in a quantity sufficient to react with the cyanuric acid and form a precipitate. The insoluble precipitate can then be vacuumed or removed through the filtration system of the pool.

Abstract: A waste treatment method for metal hydroxide electroplating sludges. Metal hydroxide sludges from the treatment of electroplating waste waters are rendered environmentally safe. The sludges are first dewatered and heated to a temperature sufficient to cause the metal hydroxides to convert to metal oxides. Predetermined quantities of silica and soda, or sources thereof, are mixed with the metal oxides. The mixture is further heated to a temperature sufficient to cause fusion of the mixture and form a slag-like composition having the metal oxides in chemical solution. The slag-like composition is then cooled to ambient temperature. The structure of the cooled slag-like composition is predominantly crystalline, having the metal oxides in solid solution in either a precipitate phase or a silicate matrix. The slag-like composition is resistant to corrosion even in an acidic environment.

Abstract: Free cyanide-containing wastewater is treated to destroy the free cyanide content thereof by the step of treating said water with sulfur in the form of polysulfide in an integrated process wherein thiocyanate is also eliminated to produce a non-hazardous wastewater effluent and treating the wastewater in a second step with cultures of bacteria of the genus Thiobacillus in combination with nitrifying bacteria which oxidize ammonia to nitrite to nitrate. The first step is preferably carried out in the presence of a cationic surfactant, preferably a quaternary cationic surfactant, as a catalyst.

Abstract: A method of removal of cyanide and metal ions from electroplating waste waters is described. The cyanide, as hydrogen cyanide, is purged with air and then absorbed efficiently in 1.5% sodium hydroxide solution. The purge is effected by dispersing air bubbles in the waste water after adjusting the pH of the water to one within the range of from 4 to 6.5. The cyanide ions are converted to hydrogen cyanide and entrained in the air bubbles for transport to a separate vessel for absorbtion in the sodium hydroxide solution. The apparatus employed is a closed system to avoid the hazards associated with hydrogen cyanide.

Abstract: A process is provided for detoxifying an aqueous solution containing a cyanide by employing hydrogen peroxide in the presence of a solid catalyst. The solid catalyst comprises a transition metal supported on an aluminum oxide and/or silicon oxide base.

Abstract: Free cyanide-containing wastewater is treated to destroy the free cyanide content thereof by the step of treating said water with sulfur in the form of polysulfide in an integrated process wherein thiocyanate is also eliminated to produce a non-hazardous wastewater effluent and treating the wastewater in a second step with cultures of bacteria of the genus Thiobacillus in combination with nitrifying bacteria which oxidize ammonia to nitrite and nitrite to nitrate. The first step is preferably carried out in the presence of added metallic zinc.