Abstract: An in situ process for treating ambient solid materials (e.g., soils, aquifer solids, sludges) by adding one or more divalent metal cations to the ambient solid material. The added divalent metal cations, such as Cu2+ or Zn2+, combine with metal oxide/hydroxides (e.g., ferric oxide/hydroxide or aluminum oxide/hydroxide) already present in the ambient solid material to form an effective sorbent material having a large number of positively-charged surface complexes that binds and immobilizes anionic contaminant species (e.g., arsenic or chromate). Divalent metal cations can be added, for example, by injecting an aqueous solution of CuSO4 into an aquifer contaminated with arsenic or chromate. Also, sludges can be stabilized against leaching of anionic contaminants through the addition of divalent metal cations. Also, an inexpensive sorbent material can be easily formed by mixing divalent metal cations with soil that has been removed from the ground.

Abstract: Disclosed herein is a process for reducing or substantially eliminating chromium in non-volatile residue obtained from a certain processes, and particularly from cyclohexane oxidation processes.

Abstract: Disclosed are methods, devices and apparatus for bioremediation of mixed waste aquifers, based on a synergistic combination of reductive treatment using zero-valent iron and anaerobic biotransformations. Also disclosed are methods for in situ and ex situ remediation of groundwater and wastewater via these iron-bacterial compositions in a variety of devices including batch reactors, permeable and semipermeable reactive barriers, flow-through reactors, fluidized bed reactors, and sediment tanks.

Abstract: A unique filtration device (10) which removes metal ions from a contaminated aqueous stream through the use of partially hollow wicking fibers (20) impregnated with a selected liquid (18) which can capture the metal ions in the aqueous stream. The wicking fibers (20) are formed into a filter element (12) which extends from a chamber (16) through which the aqueous stream is directed into a chamber (18) wherein the unwanted metal ions are removed from the extracting liquid (18). The wicking fibers (20) include internal longitudinal cavities (22) each with a relatively small longitudinal extending opening (24). The wicking fibers (20) are filled with the selected liquid extraction (18) which remains within the fiber through capillary action by which capillary action the individual wicking fibers (20) rapidly draw the selected liquid,(18) with which they comes into contact, through the internal cavities (22).

Abstract: A treatment effective for removing or substantially reducing the amount of Cr+6 present in drinking water or wastewater is described. The method includes adding a stannous salt of a non-carbon acid, in an amount effective to reduce most or substantially all of the chromic ion in the water.

Abstract: An in situ method and system for reductive dechlorination, the precipitation of chromium, the precipitation of heavy metals, and microbial denitrification. The invention comprises the formation of in situ anaerobic reactive zones to precipitate and filter out dissolved heavy metals as metallic sulfides, to degrade nitrate to nitrogen gas, to reduce chlorinated hydrocarbons to ethene, and to precipitate and filter out chromium. The invention is comprised of an injection well or wells that extend into a contaminated groundwater. A conduit located within the injection well conveys a reagent to the contaminated groundwater. The reagent may be a carbohydrate rich solution. Microbes digest the carbohydrates to produce sulfate reducing and methanogenic conditions within the reactive zone that include a dissolved oxygen level less than about 0.5 mg/l, a redox potential less than about −250 mv, and a dissolved organic carbon to contaminant ratio of greater than about 50:1.

Abstract: A process for the treatment of waste water containing heavy metals in which sulphur components and/or metals are biologically reduced to precipitate the metals as water-insoluble metal species, which are separated from the waste water. The biological reduction and the precipitation of the metal species are carried out in a moving sand bed, in which sand particles partly immobilize the bacteria and retain the precipitated metal species, treated waste water is separated from the precipitated metal species and the precipitated metal species are subsequently separated from the sand particles. Metals like selenium and uranium can be precipitated without sulphur components, whereas metals like antimony, cadmium, copper, zinc and the like are precipitated as sulphides.

Abstract: A method is taught for converting metal contaminants in the soil to less toxic forms as well as permitting their removal from groundwater. A first reactive solution comprising ferrous sulfate and an acid selected from the group consisting of sulfuric acid and phosphoric acid is injected to decomplex contaminants and precipitate them as insoluble compounds. A second reactive solution comprising hydrogen peroxide, and an acid selected from the group consisting of sulfuric acid and phosphoric acid is then injected to destroy organic liquids and enhance decomplexation. The pH of the first solution may range from 3 to 5, and the pH of the second solution range from 3 to 7, preferably 5 to 7. The process is particularly effective where chromium compounds such as hexavalent chromium are the contaminants.

Abstract: A method is disclosed for treating a flushing solution from an ion exchanger used in electroplating operations by co-precipitating or selectively precipitating out metal hydroxides derived from metal ions from the structures being plated in the electroplating bath, metal ions from the electrodes use in the electroplating bath and metal ions from the plating metal used in the electroplating bath, and a pH raising agent having a cation with a valence of at least 2. After the metals are precipitated out of the flushing solution, the flushing solution is aerated with carbon dioxide to precipitate out the cation from the pH raising agent as a carbonate. The carbonate precipitate is removed from the flushing solution and the resulting solution consists essentially of water that may be recycled for use in the electroplating plant or safely discharged into the environment.

Abstract: A process for removing heavy metals from water is provided. The process includes the steps of introducing magnetite to a quantity of water containing heavy metal. The magnetite is mixed with the water such that at least a portion of, and preferably the majority of, the heavy metal in the water is bound to the magnetite. Once this occurs the magnetite and absorbed metal is removed from the water by application of a magnetic field. In most applications the process is achieved by flowing the water through a solid magnetized matrix, such as steel wool, such that the magnetite magnetically binds to the solid matrix. The magnetized matrix preferably has remnant magnetism, but may also be subject to an externally applied magnetic field. Once the magnetite and associated heavy metal is bound to the matrix, it can be removed and disposed of, such as by reverse water or air and water flow through the matrix.

Abstract: A method for improving the efficiency and usable life in a cross flow membrane filter used to remove contaminants from bilgewater. The bilgewater is passed upstream of the cross filter membrane through a fluid-pervious filtration media which has been infused with an absorbtion composition comprising a homogeneous thermal reaction product of an oil component selected from the group consisting of glycerides, fatty acids, alkenes, and alkynes, and a methacrylate or acrylate polymer component. The contaminants are thereby immobilized at the media. The purified output from the infused filtration media is then provided as input for the cross flow membrane filter.

Abstract: A method and apparatus for removing contaminants from an oily bilgewater. In the method the bilgewater is passed through a fluid-pervious filtration media which has been infused with an absorbtion composition comprising a homogeneous thermal reaction product of an oil component selected from the group consisting of glycerides, fatty acids, alkenes, and alkynes, and a methacrylate or acrylate polymer component. The contaminants are thereby immobilized at said media, and the purified bilgewater having passed through the filtration media is discharged, e.g. into a body of navigable water.

Abstract: A batch or continuous process for the removal by flocculation of silicon and heavy metal contamination from aqueous waste streams by the addition of an aluminum salt, particularly, aqueous streams recycled as electrolyte in the electrolytic production of alkali metal or alkaline earth metal chlorates. The process is particularly suited to the removal of heavy metals and silicon contamination in an electrolyte recycled to an electrolytic cell subsequent to the removal by crystallization of a chlorate salt. An aluminum salt, such as aluminum chloride, aluminum chlorohydrate, and polyaluminum chlorides including polyaluminum chloride sulfates is effective as a flocculating agent.

Abstract: Embodiments of the present invention relate to methods and systems for removal of contaminants from aqueous solutions. The methods and systems of these embodiments are particularly suited to removal of arsenic species as well as transition-metals, post-transition-metals, phosphates and other contaminants in aqueous solutions. The methods and systems of embodiments of the present invention provide for the addition of a reagent to a contaminated solution in combination with a pressurization process and a depressurization process. Contaminant particulates and solids produced in these processes may be removed by conventional separation techniques.

Abstract: A media is used to remove species from aqueous solutions, particularly in the treatment of water to enable it to be suitable for drinking. The media includes a material selected from the group consisting of zirconium hydroxide, titanium hydroxide, hafnium hydroxide and combinations thereof. A preferred form of the media is a layer having an aspect ratio of at least 1:1, more preferably, at least about 10:1. Removed from the water are species selected from the group consisting of arsenate, selenate, chromate, borate, perchlorate, fluoride and combinations thereof. In particular arsenite (As+3) containing species are also removed from water. Arsenite may be removed from water to levels not greater than 10 parts per billion with a single exposure to the media. The media is selective for certain species over others.

Abstract: A process and a system for removal of metals from ground water or from soil by bioreducing or bioaccumulating the metals using metal tolerant microorganisms Saccharomyces cerevisiae. Saccharomyces cerevisiae is tolerant to the metals, able to bioreduce the metals to the less toxic state and to accumulate them. The process and the system is useful for removal or substantial reduction of levels of chromium, molybdenum, cobalt, zinc, nickel, calcium, strontium, mercury and copper in water.

Abstract: A method for treating in situ large bodies of water contaminated with heavy metals and having varying density stratas to immobilize the contaminant metals is disclosed. The method, or process for in situ immobilization of metals is focused on treating large bodies of water having metals therein that are also adjacent a border of soil or earthen materials in an attempt to immobilize the metals from penetrating through the soil. Initially, the density mean of the body of water is determined, which is densest typical at regions at or approaching 4 degrees C.

Abstract: A material and method for removal of environmental oxyanions (and especially phosphates), the material comprising a substrate such as a clay modified with complexing elements selected from Group IIIB, Group IVB, and lanthanide elements (or a mixture of such elements). The resultant modified substrate can bind oxyanions and make them unavailable for utilisation in the environment; in the case of phosphates, by algae and the like. The method includes forming a capping of material at the sediment/water interface, applying the material in the form of pellets at the sediment/water interface, or injecting the pellets into the sediment.

Abstract: An in situ method and system for reductive dechlorination, the precipitation of chromium, the precipitation of heavy metals, and microbial denitrification. The invention comprises the formation of in situ anaerobic reactive zones to precipitate and filter out dissolved heavy metals as metallic sulfides, to degrade nitrate to nitrogen gas, to reduce chlorinated hydrocarbons to ethene, and to precipitate and filter out chromium. The invention is comprised of an injection well or wells that extend into a contaminated groundwater. A conduit located within the injection well conveys carbohydrates and sulfates to the contaminated groundwater. Microbes digest the carbohydrates to produce sulfate reducing and methanogenic conditions within the reactive zone that include a dissolved oxygen level less than about 0.5 mg/l, a redox potential less than about −250 mv, and a dissolved organic carbon to contaminant ratio of greater than about 50:1.

Abstract: A method is disclosed for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal from waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the like are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: A method is disclosed for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal from waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the like are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: A method of removing a dissolved metal constituent from a contaminated liquid is provided. The method comprises the steps of: providing a flow stream containing the contaminated liquid; providing a plurality of shell components formed by comminuting a shell stock including at least one shell having a biomineralized calcium carbonate composition; combining the shell components with the flow stream; and converting at least one shell component to a substantially insoluble biometallic nodule by maintaining contact between the shell components and the dissolved metal constituent over a predetermined time period. The biometallic nodule thus formed contains at least a portion of the metallic constituent in a biogenic metallic carbonate form. After their formation, the biometallic nodules are separated from the treated flow stream.

Abstract: The process of the present invention comprises the steps of (a) a step of dissolving a condensed tannin powder in an aqueous alkaline solution, (b) a step of admixing an aqueous aldehyde solution with the aqueous solution obtained in the step (a), (c) a step of adding the aqueous solution obtained by the above step (b) to a hydrophobic solvent containing a polyether type nonionic surfactant under heating and stirring to disperse the aqueous solution in the form of droplets in said hydrophobic solvent and (d) evaporating water components from the above-mentioned droplets to form a spherical and gelled insoluble tannins. Water content of the gel can be widely controlled as 5 to 90% as compared with the conventional adsorbent and the network structure and molecular space are changed depending on the size of the metal ion to be adsorbed so that a gelled insoluble tannin which can increase an adsorption capacity of metals can be obtained.

Abstract: A method is disclosed for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal form waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the lie are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: A non-iron sulfide is introduced into an iron-containing zone to form ferrous sulfide. A contaminated aqueous composition is then contacted with the ferrous sulfide to react with said contaminants.

Abstract: An aqueous solution, for example, effluent from an off-gas scrubber, is treated to remove metal and metalloid ions by in situ precipitation of ferrous ions by the addition thereto of a ferrous ion-containing solution, salt or other such ferrous ion-containing source and a hydroxyl-yielding base in the presence of the metals and metalloids. The reaction conditions include a temperature of at least about 60° C., and a pH of from about 6 to about 10.

Abstract: An in situ method and system for reductive dechlorination, the precipitation of chromium, the precipitation of heavy metals, and microbial denitrification. The invention comprises the formation of in situ anaerobic reactive zones to precipitate and filter out dissolved heavy metals as metallic sulfides, to degrade nitrate to nitrogen gas, to reduce chlorinated hydrocarbons to ethene, and to precipitate and filter out chromium. The invention is comprised of an injection well or wells that extend into a contaminated saturated zone. A conduit located within the injection well conveys carbohydrates and sulfates to the contaminated saturated zone. Microbes digest the carbohydrates to produce sulfate reducing and methanogenic conditions within the reactive zone that include a dissolved oxygen level less than about 0.5 mg/l, a redox potential less than about -250 mv, and a dissolved organic carbon to contaminant ratio of greater than about 50:1.

Abstract: Phosphates and chromates are selectively removed from contaminated water by a new class of sorbent, referred to as a Polymeric Ligand Exchanger (PLE). The exchanger bed comprising a styrene-divinylbenzene or polymethacrylate matrix having an electrically neutral chelating functional group with nitrogen or oxygen donor atoms, and a Lewis-acid type metal cation, such as copper, bonded to the chelating functional group in a manner that the positive charges of the metal cation are not neutralized. PLEs are very selective toward phosphates and chromates, chemically stable, and also amenable to efficient regeneration.

Abstract: The present invention relates to a process for treating contaminated water to precipitate metals without increasing the total dissolved solids content. In particular, the invention relates to the use of phosphoric acid and calcium hydroxide or calcium oxide to adjust the pH of chromium contaminated groundwater during the treatment process without increasing the total dissolved solids (TDS).

Abstract: Aluminum particles are reacted with heavy metal ions in a first acidic aqueous solution to form heavy metallic particles that are suitable for recycling and reuse when recovered from the first aqueous solution. The first residual aqueous solution may also contains ferrous ions obtained by acid redissolving a co-precipitated heavy metal hydroxide and ferrous hydroxide sludge that is produced in the treatment of a dilute chelated heavy metal solution. The first residual aqueous solution with heavy metals substantially removed is recycled and reused as the ferrous reagent for treating said dilute chelated heavy metal bearing solution. The process disclosed herein is useful for treating both dilute and concentrated wastes and wastewaters generated by industries such as metal plating and metal etching and printed circuit board fabrication.

Abstract: A method for treating heavy metal contaminated soils, particularly those containing hexavalent chromium, which includes a first soil washing at pH 9-12 with an anionic synthetic organic flocculant followed by a liquid-solid phase separation such as by gravity separation including sedimentation, an optional second soil sludge washing at pH 2.5-3.0 with addition of a metal valency reducing agent which when done is followed by a second liquid-solid phase separation using a cationic synthetic organic flocculant, combining the first and second stage liquids and optional treating the liquid phase with a metal valency reduction agent such as sodium metabisulfite under acidic conditions followed by treatment with an alkaline agent to form insoluble metal hydroxide which is separated in a phase separation process and is combined with the final sludge, recycling the liquid from washing stage or stages for use in soil processing, dewatering the separated sludge or sludges using a separation method (e.g.

Abstract: A method and a system which enable simple and inexpensive removal of heavy metals from a heavy-metal-containing substance. In this method, a substance containing heavy metals and water are introduced into a mixing bath in proportions by weight of 1:3 to 1:6. A strong acid is added to the mixture, and the mixture is stirred while its pH is maintained at a pH lower than 4. As a result of stirring of the substance at a pH 4, heavy metals are extracted into the liquid as metal ions. The metal-ion-containing liquid is input to a heavy metal precipitation bath, and the pH of the liquid is increased to a pH higher than 10 by addition of alkali to the liquid. Gas bubbles of carbonic acid gas are input to the liquid from a lower portion of the heavy metal precipitation bath, and they are broken into a large quantity of small gas bubbles of carbonic acid gas by turbine blades. The large quantity of gas bubbles of carbonic acid are brought into contact with the metal-ion-containing liquid having a pH higher than 10.

Abstract: Method and apparatus for handling water used in plating processes to eliminate discharge of pollutants including a plating tank for chrome plating selected materials, at least one rinse tank which holds rinse water where parts from the plating tank are rinsed to remove chrome compounds used in the plating tank and transfer means to transfer water from the rinse tank to a purification tank where hydrazine is added to the rinse water in quantities sufficient to maintain selected pH in the water returned to one of the rinse tanks for precipitation of the chromic compounds to chromic hydroxide which can be easily filtered for disposal as a dry material. High quality water such as deionized water is added to the rinse tank to makeup lost water and a catalyst such as cobalt salt can be added to the purification tank to assist in reduction of the chromic compounds.

Abstract: A process of selectively separating a target metal contained in a solid matrix from the solid matrix by contacting a solid matrix containing a target metal with an aqueous solution including a water-soluble polymer adapted for complexation with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solid matrix is disclosed.

Abstract: A method for recovering and separating precious and non-precious metals from waste streams, which removes, separates, and recovers such metals in a cost effective manner with more than 95% removal from waste streams and with minimal amounts of unprocessed solids and sludge remaining in the environment. Metals such as chromium, manganese, cobalt, nickel, copper, zinc, silver, gold, platinum, vanadium, sodium, potassium, beryllium, magnesium, calcium, barium, lead, aluminum, tin; and the like are removed and recovered from the waste streams with at least 95% removal and other metals and compounds, such as antimony, sulfur, and selenium are removed and recovered from waste streams with at least 50% removal. The method employs a unique complexing agent comprising a carbamate compound and an alkali metal hydroxide which facilitates the formation of the metals into ionic metal particles enabling them to be readily separated, removed and recovered.

Abstract: The invention relates to a method for treating waste water sludge comprising at least one metal originating from a waste water treatment coagulant, and phosphorus and heavy metals in order to recover said at least one metal and phosphorus and to discharge said heavy metals. In this method said waste water sludge is acidified to dissolve metals contained in the sludge thereby yielding an acidified sludge solution containing at least 1% by weight of at least one metal to be recovered. In a first precipitation stage the pH of said acidified sludge solution is raised to precipitate at least one metal to be recovered as a phosphate, and thereafter the phosphate precipitate is separated, thereby leaving a solution comprising heavy metals. In a second precipitation stage the pH of said solution comprising heavy metals is raised and, if necessary, an appropriate chemical is added to precipitate heavy metals, and thereafter the precipitate is discharged.

Abstract: A method for removing pollutants from water, according to the preferred embodiment of the present invention, comprises the steps of providing algal spores for seeding, providing a source of water for flowing through a floway, and the water contains a quantity of pollutants and has a pH on entry into said floway, providing a growing surface in the floway upon which the algal spores form an attachment, subjecting the algal spores in the floway to operating conditions resulting in the formation of an algal turf in which the algae has cell walls on its surface, adjusting the floway operating conditions such that a predetermined pollutant precipitates onto and/or into the algal cell walls but not into the water, and harvesting a portion of the algal turf including the cell walls onto and/or into which the pollutants have precipitated.

Abstract: A method for removing heavy metals and halogenated hydrocarbons from contaminated groundwaters is provided. The method provides utilizing a treatment solution comprising a soluble source of organic carbon, ferrous iron, and sulfate. Additionally, the treatment solution may comprise sulfate reducing bacteria as well as nutrients for bacterial metabolism. The treatment is designed to stimulate the growth of naturally occurring sulfate reducing bacteria such that the metals are coprecipitated in iron sulfide and the hydrocarbons are reduced to innocuous byproducts.

Abstract: The invention relates to the use of barium sulphide or strontium sulphide for the removal of heavy metals in industrial acidic solutions.The invention is applicable to the purification of contaminated acids, in particular of spent battery acid, or of industrial solutions of titanyl sulphate.

Abstract: A waste water stream containing a heavy metal such as chromium, zinc, copper, and the like is directed from a source after pH adjustment to a tank containing adsorption material in the form of granular activated carbon. A waste water stream is directed to the tank in either an upward or downward flow mode. The heavy metal is adsorbed onto the surface of the adsorption material which is pretreated to an initial pH in the range between about 1.5 to 2.5. The water stream free of the metal contaminant is directed to an effluent tank for safe discharge. Thereafter a stripping solution preferably containing sulfuric acid is circulated through the tank to remove the adsorbed metal for the adsorption material. The metal is carried by the stripping solution from the tank to an electrolytic metal recovery unit. The unit includes a cathode terminal and the stripping solution passes through a voltage potential resulting in electrolytic deposit of the heavy metal onto the cathode terminal.

Abstract: Adsorbent alumina particulates which comprise coagulated droplets, extrudates or crushed alumina particles having a volume of pores with a diameter greater than 80 .ANG. of at least 0.15 cm.sup.3 /g and a particle size of less than 4 mm are well suited for adsorbing chelated organometallic compound values thereon, in particular from a medium of polymerization comprising same.

Abstract: In a process of remediating chemical contamination of a pond contaminated with one or more toxic heavy metals or aromatic compounds, the steps include: preparing a silage of grass clippings, placing the silage on the surface of a pond, and inoculating the pond with an alga and Bacillus cereus in sufficient quantities to cause a mixed algal and bacterial bloom to form on the pond surface and become annealed to the silage, leaving the silage with the annealed bloom on the surface of the pond for a sufficient amount of time to allow the bloom to withdraw at least some of the toxic heavy metal content or to degrade at least some of the aromatic compound content of the pond, and removing the silage with the annealed bloom from the pond.

Abstract: The present invention is a method to remove metals from solutions by precipitating the metals and adding cellulosic fiber to the solution. The precipitates attach to the cellulosic fibers to form products. The products may be removed from the solution by gravity separation techniques or by filtration. The removed products may be dewatered and incinerated. The method provides a simple and effective technique for removing low concentrations of metals from high volume solution streams.

Abstract: Process for the inertization of liquid waste, mud and solid waste, containing sulphates and heavy metals, which comprises a neutralization step of the compounds to be treated and an anaerobic reduction step of the sulphate ion to allow the formation of sulphide ions necessary for the process. A consortium of sulphate-reducing bacteria and lactobacilli is used, with whey as a carbon and nitrogen source.

Abstract: A method for the removal of metal from a metal-containing aqueous medium wherein the aqueous medium is passed through a particulate carrier material in the presence or ferrous iron and an oxidant and at such velocity and in such direction that the carrier material particles are fluidised in the aqueous medium and wherein metal-containing coatings are formed on the surfaces of the carrier material particles and wherein the particles thus coated are separated from the aqueous medium. A method for the production of iron oxyhydroxide-containing adsorbent wherein the carrier material particles are fluidised in an aqueous medium in the presence ferrous iron and an oxidant so as to form iron oxyhydroxide coatings on the particles and wherein the particles thus formed are separated from the aqueous medium.

Abstract: Process for the decontamination of decontaminants in waste waters, wherein the waste water stream to be treated pass sequentially through following process steps,waste water treatment with hydrogen peroxide (H.sub.2 O.sub.2), irradiating at the same time with UV light,treatment with a reducing agent such as sodium dithionite,precipitation of existing metal contaminants, optionally followed by a filtration and/or a treatment with a selective ion exchanger.

Abstract: Metals and organics are extracted from solution by co-precipitating them with a gel comprising aluminum hydroxide and a complexing agent such as EDTA. After the gel is processed to remove the metals and organics, it can be recycled for further use by dissolving it in a high-pH solution, leaving no secondary waste stream. A number of alternative complexing agents perform better than EDTA.

Abstract: A process for treatment of hazardous liquid waste comprising trace amounts of hazardous elements in solution as oxyanions by oxyanion fixation within ettringite and related minerals. In accordance with the disclosed process, reagents for forming ettringites are mixed with the waste stream resulting in the formation of oxyanion-substituted ettringite and related materials. The resulting ettringite and related minerals are separated by filtration from the liquid. Thereafter, the liquid, having an elevated pH, is neutralized by carbon dioxide sparging resulting in precipitation of excess reagents in the liquid. Thereafter, the precipitates are filtered, producing a clean liquid.

Abstract: Heavy metal ions react with iron particles in acidic aqueous solution to form heavy metallic particles that are suitable for recycling and reuse when recovered from the aqueous solution. Chelating agents that are present are deactivated by bonding to ferrous ions produced from the iron particles. An alkali metal hydroxide is utilized to precipitate remaining heavy metal ions including ferrous and ferric ions which are recycled to the acidic aqueous solution.

Abstract: A process for treating industrial waste water containing hexavalent chromium (Cr.sup.+6) and other heavy metals is disclosed which comprises reduction of Cr.sup.+6 to trivalent chromium (Cr.sup.+3) and the precipitation thereof with other heavy metals by addition of sulfide ion and ferrous ion to the waste stream at a pH of about 7 to 9 under conditions such that sludge production by the process of the invention is substantially less than that characteristic of prior art processes. Polymers are added to the solution to assist flocculation and clarification of the waste stream. More specifically, the invention comprises adding sulfide ion in a sulfide to hexavalent chromium ratio of about 0.7-2.5:1 and adding ferrous ion in a ferrous to hexavalent chromium ratio of about 0.5-5.0:1. The waste stream pH is preferably maintained in the range of about 7.2 to 7.5.