Abstract: A simple, rapid, efficient and inexpensive process for on-site recycling of wastewater with minimal odor wherein the solid wastes generated by the water treatment process are dewatering on-site by solar energy to water content levels below those required for disposal. All operations, including solar dewatering, are accomplished in a compact unit which may be mobile. The solar dewatering unit includes a drying pan over which a solar collector window arrangement is disposed. In the process, wastewater, a water purifying composition and an oxidizing agent are additively mixed together in a first reactor settling tank and the resulting composition is neutralized to a pH of between 7.5-9.4. The added water purifying composition is then allowed to precipitate wherein it binds to and precipitates heavy metals as well as other impurities. The precipitated purifying composition forms a non-hazardous sludge at the bottom of the tank.

Abstract: A method to remove heavy metals concentrations in water down to very low levels is described. The method calls for the addition of a soluble sulfide to the water. This is followed adding a soluble iron reagent such as ferrous sulfate or ferrous chloride. The water is aerated. As an alternative to aeration, the pH of the water can be increased. Finally, the solids generated from the above steps are separated from the water. This method has been shown to remove heavy metals, particularly copper and zinc, from actual industrial wastewater to very low concentrations, i.e., below about 100 ppb. Furthermore, the treated water is free of sulfide. The byproduct sludge comprises iron sulfide, iron oxides, iron hydroxides, and the heavy metal sulfides.

Abstract: The aqueous wash stream of an electrolytic precipitation system treating natural gas liquid (NGL) is maintained at a pH sufficiently basic to decrease the solubility of iron sulfide in the aqueous wash stream.

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: Heavy metals can be effectively complexed with a derivative of a fructan, which derivative contains complexing groups chosen from --X--CY--ZM, --X--CY--ZM, --X--CY--S--S--CY--X--Q, --PY'(--Z'M).sub.2, --SO.sub.3 M and --NR--CH.sub.2 --COOM, where M is a metal or hydrogen, Q denotes the residue of an alcohol or polyol, R is hydrogen or carboxymethyl and X, Y, Y', Z and Z', independently of one another, are O, S or NH and at least one of X, Y and Z is S, with a degree of substitution of 0.1-2.5. The complexing groups are in particular xanthate, xanthide or dithiocarbamate groups.

Abstract: The present invention relates to a method of treatment of acid waste waters or acid drainage waters containing metals comprising ferrous and ferric ions, the method comprising increasing the pH of the acid waste to at least 7.5 by addition of an alkaline reagent under conditions such that ferrous ions are stable with respect to oxidation to ferric ions, to form a precipitate and collecting the precipitate.

Abstract: An activated carbon-crystalline titanium and/or tin silicate composite for purifying waste streams and method of making. The method involves providing a combination of a synthetic carbon precursor, and titanium and/or tin silicate, followed by curing, carbonizing, and activating the carbon precursor. The composite is used to purify fluid streams such as water, of pollutants such as VOC's, heavy metals such as lead, and chlorine.

Abstract: Disclosed is a method for treating highly concentrated wastewater by electrolysis and oxidization, said method being characterized in that the electrolysis and oxidization are carried out in a fluidized bed of a suitable particulate carrier. The electrolytic reduction efficiency of ferric ions is improved by the fluidized particulate carrier, and thus a high proportion of iron(III) to iron(II) can be sustained in the system. This invention allows extensive purification of wastewater with improved efficiency.

Abstract: Process and apparatus for treating an aqueous effluent with high concentrations of silver and ferric/ferrous complexes using multiple additions of one or more water-soluble sulfur containing polymer chelating agents, with optional additions of non-polymeric sulfur containing compounds. The presence of a high concentration of both dissolved silver and ferric/ferrous complexes prevents efficient silver removal by precipitation and the achievement of a very low residual silver concentration. By using multiple additions of the chelating agent(s), a higher degree of silver removal can be achieved than would be possible with the same amount of chelating agents added in a single stage. Effluent from photo finishing operations, particularly minilabs, can be effectively treated so that there is essentially no silver remaining in the treated effluent.

Abstract: An apparatus and method for removing contaminating metal ions and sulfate ions from acidic aqueous solution such as waste mine water which features passing the solution between pairs of electrodes, each pair of electrodes impressed with a voltage selected according to specific ion species and then adding chemical agents to raise the pH and form precipitates of the metal and sulfate ions. A magnetic field is applied during at least the first mixing step. The precipitate is then separated from the water with settling and filtering steps. The clarified solution is treated by reverse osmosis to concentrate the ammonium.

Abstract: A process for removing lead and copper from drinking water discharged from a drinking water outlet while suppressing the concentration of phosphate ions comprising directing the water through a matrix comprising phosphate mineral with a very low phosphate solubility, and a solid carbonate mineral which is slightly soluble in water. The matrix is sized such that there is sufficient contacting between the water and the matrix to form a lead phosphate precipitate, reduce the lead concentration in the water to below 15 parts per billion, and suppress the phosphate ion concentration to 5 mg/L, preferably 3 mg/L, or below.

Abstract: Disclosed are formed composite material compositions suitable for use in the removal of heavy metals from aqueous systems, a process for preparing said composite materials and a process for the removal of heavy metals using said composite materials. Formed particulate composite material compositions are comprised of (A) at least one ion exchange material; (B) at least one activated carbon; and, optionally, (C) at least one binder material. The method for preparing said composite material compositions comprises first mixing components (A), (B) and, optionally, (C), then forming particles from said mixture. The method for removing heavy metals from aqueous systems containing one or more heavy metals comprises contacting said aqueous system with one or more of the composite materials until the heavy metals are substantially removed from the aqueous system.

Abstract: An apparatus and method for removing hydrocarbon contaminants and heavy metal ion contaminants from wastewater stream comprising the introduction of iron ions into the stream. In one embodiment, the ions are introduced by applying an electrical current through a bed of iron particulates in the form of steel wool and iron nodules. In another embodiment, the iron salts are added to the waste stream and the iron ions are reduced to a more reactive lower valence state by electric current.

Abstract: A method for removing selenium from waste water is disclosed comprising reducing selenium oxide with carbohydrazide in a solution comprised of the selenium oxide to form elemental selenium.

Abstract: A method for efficient removal of lead co-catalyst species from organic process streams arising from diaryl carbonate synthesis, by contacting the organic reaction mixtures with an aqueous acid, salt, or acid/salt solution, thereby extracting the treated mixture into an aqueous phase, or by treating the organic reaction mixtures with solid oxalic acid or oxalic acid salt, or an aqueous solution of oxalic acid or oxalic acid salt, thereby resulting in precipitation of the lead. The precipitated lead may then be calcined to provide a lead compound that is catalytically active in the carbonylation of phenol to yield diary carbonates. Use of these methods will substantially reduce both financial and environmental concerns for the preparation of diaryl carbonates.

Abstract: The surprising ability of the polysilicate microgels commonly known as "activated silica" to adsorb and to release heavy metals selectively as a function of pH is used in a novel method for separating metals from dilute aqueous solution by means of selective precipitation with and recovery from an activated silica absorbent, selected changes to the pH. The process is particularly intended for the economic purification of contaminated waste streams to recover valuable but toxic heavy metals from such effluents at a lower cost than hitherto possible, using an activated silica substrate which may be regenerated by alkali treatment.

Abstract: A reverse osmosis process for treating a phenolic stripped sour water stream containing soluble and insoluble contaminants is provided. Prior to passage through a reverse osmosis membrane, the phenolic stripped sour water stream is cooled, subjected to air flotation and filtered through a sand filtration system to remove insoluble contaminants, and passed through a water softener to remove divalent and trivalent metal cation contaminants. The pH of the stream is adjusted prior to the water softener, and again prior to the reverse osmosis membrane, to stabilize the solubility of soluble organic contaminants present within the stream.

Abstract: A continuous process for the biological solubilization of heavy metals from primary or other metal-laden sewage that utilizes indigenous sulphur oxidizing bacteria and elemental sulphur as the energy source, prevents nitrite formation and minimizes the residual sulphur remaining in the processed biosolids.

Abstract: Process for preparing fine-particle, water-insoluble polymers of aziridines by polymerizing aziridines, preferably ethylenimine, in the presence of crosslinkers which contain at least two functional groups, and in at least one ether, and also modified, water-insoluble polymers of aziridines which can be obtained by reacting fine-particle, water-insoluble, crosslinked polymers of aziridines, in aqueous medium, with carbon disulfide or formaldehyde and a nucleophilic agent from the group consisting of alkali metal cyanides, primary amines, secondary amines, alkali metal sulfites and alkali metal phosphites, and use of the modified and non-modified fine-particle, water-insoluble polymers for immobilizing active compounds, as absorbents for aldehydes, ketones and acids, and also for removing heavy metal ions from wastewaters.

Abstract: Municipal solid waste is classified as to density as well as size in a perforated inclined trommel through which a gas stream is flowed inwardly through the perforations and downwardly to entrain aid remove paper and plastics through the lower end. Ferrous and non-ferrous metals are removed from the residue which is digested anaerobically in two stages with an intermediate steam explosion treatment to expose cellulose fibers coated with lignin. Mercury may be removed as a vapor phase in an initial stage of the steam heating and condensed and collected. An aqueous phase of the anaerobic digestate may be treated to remove heavy metals and may be discarded or reused to slurry solid phase incoming to a digester. The solids phase of the anaerobic digestate may be acidified to solubilize heavy metals which are recovered by electrodeposition from the solution. The depleted residue can be neutralized and disposed of.

Abstract: Selenium-containing wastewater is sequentially treated through use of biological treatment means (6), chemical treatment means (12), and filtration means (14). In the biological treatment means (6), raw waste water (16) is subjected to anaerobic biological treatment so as to reduce selenate ions and/or selenite ions (soluble selenium) present in the raw waste water (16) to simple selenium, which is insoluble, to thereby remove the selenate ions and/or the selenite ions in the form of insoluble simple selenium. In the chemical treatment means (12), for example, a metal salt that reacts with soluble selenium to form an insoluble selenium compound is added to water treated by the biological treatment means (6), to thereby remove residual soluble selenium in the form of the insoluble selenium compound. In the filtration means (14), an insoluble substance remaining in water treated by the chemical treatment means (12) is removed through filtration.

Abstract: A method for removing a heavy metal from sludge, including the step of putting the sludge into contact with a treating liquid to dissolve the heavy metal contained in the sludge into the treating liquid. The treating liquid is formed of either A or B, where (A) is an aqueous solution of phosphoric acid, and (B) is an aqueous solution of phosphoric acid containing at least one of B1 and B2, where (B1) is at least one acid other than phosphoric acid, and (B2) is at least one oxidant. The concentration of the phosphoric acid in the treating liquid is 3% by weight or more. Alternatively, the sludge is put into contact with the treating liquid at a temperature of 40.degree. C. or higher.

Abstract: A method for removing metal contaminates from solution using mercapto-functional silica xerogels. The mercapto-functional silica xerogels are characterized by having a surface area greater than 365 m.sup.2 /g, an average pore diameter of at least 6 nm, and a pore volume of at least 2 cm.sup.3 /g. The mercapto-functional silica xerogels are particularly useful for removing Group VIII metals such as platinum from solutions comprising polyorganosiloxane fluids and resins.

Abstract: Metal ions and/or complexes of metal ions are removed from a solution by formation of an insoluble chelated complex of the metal ions and a polymeric precipitating agent. A two-step process of mixing the influent with the precipitating agent is used to induce rapid precipitation and obtain large, self-agglomerated precipitate without addition of flocculating agent and/or pH adjustment. In addition, parallel loops are employed to simultaneously discharge treated metal-free solution and effectively collect/remove the precipitate-containing sludge without interfering with each other. The metal capturing capacity of the polymeric precipitant is maximized by forcing the influent solution through layers of the collected precipitate and by recycling unsaturated metal-precipitant complexes in the processing loop.

Abstract: A method of treating a biomass comprising liquid manure from animal husbandry containing heavy metals, the method comprising the steps of subjecting the biomass to an anaerobic microbial degradation to form a biogas containing i.e. hydrogen sulphide gas, conveying at least a part of the biogas through at least a part of the microbially degraded biomass to precipitate the heavy metals as metal sulphides and separating the resulting mixture in a precipitate and a supernatant.

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 process for the treatment of sewage to provide effective removal of selenium (especially the 6-valent selenium) to meet required standards for the dissolved amount of selenium, and the like, at a low cost are developed. The process and apparatus reduces selenium from the 6-valent selenium using microbiological treatment to obtain 4-valent selenium and/or simple selenium, and then provide a solid-liquid separation.

Abstract: In a method of cleaning up heavy metal-laden waters and soils, conditions are established in the soils and waters to be treated so that the microorganism present there will form hydrogen sulfide, and optionally apathogenic facultative anaerobes that are tolerant of heavy metals are added to produce hydrogen sulfide, and the hydrogen sulfide formed by microbiological action is allowed to react with the heavy metals to form metal sulfides.

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 for recovering etchant from etching waste liquid 11 containing iron chloride is disclosed, wherein iron powder is mixed with iron chloride waste solution containing metal ions having a lesser ionization tendency than iron ion in an mixing vessel so as to cause a reaction between the iron powder and the metal ions and remove the precipitated metal from the iron chloride waste solution.

Abstract: A process for treating oils and solvents contaminated by radioactive substances includes a step of subjecting the oils and solvents to the action of pre-selected micro-organisms in the presence of air and a very large volume of water, relative to the volume of oils and solvents to be treated. The micro-organisms destroy organic molecules, and in particular transform them into CO.sub.2 and H.sub.2 O. Further steps of the process include preparing a predetermined volume of water having predetermined characteristics of dissolved oxygen concentration, pH and redox potential and adding a predetermined charge of oils and solvents contaminated by radioactive substances to this volume of water, the charge corresponding to a volume of oils and solvents which is a predetermined fraction of the predetermined volume of water. The charge is subjected to the action of micro-organisms at a predetermined temperature and for a predetermined time period.

Abstract: Dendritic polymer based networks consisting of well-defined hydrophilic and oleophilic (i.e., hydrophobic) domains, are capable of performing as nanoscopic sponges for electrophilic guest moieties such as (i) inorganic and organic cations; (ii) charged or polarized molecules containing electrophilic constituent atoms or atomic groups; and (iii) other electrophilic organic, inorganic, or organometallic species. As a result of such performance, the networks yield novel nanoscopic organo-inorganic composites which contain organosilicon units as an integral part of their covalently bonded matrix.

Abstract: A drain pan is provided for removing copper ions from condensate water produced by a heating, ventilation and air conditioning unit. The pan defines a volume having two closed ends and an open top so that water can evaporate from the pan. At least one copper removing agent is placed in the pan, and a baffle is provided between the ends of the pan, for routing water entering the pan at one end through the removing agent en route to an outlet at the other end. The removing agent may include mossy zinc and/or activated charcoal.

Abstract: The invention relates to a method for separating metals present in a solution using chitosane. According to the present invention, chitosane in modified physical form is used which allows faster, more extensive fixation of the metals present in a solution. This purpose is achieved using a method in which the chitosane used is a lyophilizate of chitosane, in particular a lyophilizate of chitosane salt.

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: The present invention concerns the treatment of an aqueous effluent and consists of ridding it of the iron which it contains, notably in the form of a complex. The method according to the invention consists of treating this effluent by successively a silicate, and a magnesium and aluminium hydroxycarbonate, then decanting and filtering. The method according to the invention is particularly useful in the treatment of photographic effluents.

Abstract: The invention relates to the use of sheet silicates of the general formulaNaMSi.sub.x O.sub.2x-1.yH.sub.2 Oin which x is from 1.9 to 4, M is Na or H and y is from 0 to 20, for removing heavy metals from aqueous systems.

Abstract: A method for treating a quantity of soil contaminated with lead, copper or mercury includes mixing the contaminated soil with an acid, chloride solution, to dissolve the contaminants in the chloride solution. Soil, essentially free of the contaminants, is separated from contaminant-containing chloride solution. Contaminants are precipitated from the contaminant-containing chloride solution by addition of one or more sulfides. Precipitated contaminants are separated from the remaining solution. The remaining solution may treated by adding chloride, acid, ORP adjusting agents and used to treat an additional quantity of soil.

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: A method for recovering metals from solutions is described. A particular embodiment of the method concerns recovering copper metal from aqueous solutions containing copper ions, such as ammoniacal circuit-board etching solutions. A working embodiment of the invention includes first treating a solution containing copper ions with a sufficient amount of an acid to obtain a solution pH of from about 1 to less than about 2.5. A reducing metal, such as iron, is then added to the solution to precipitate metal ions as metals. The reducing metal has a mesh size of about 230 or greater. The metal precipitate is recovered from the solution. The method is generally sufficiently efficient to allow discharge of solutions treated according to the method of the invention into public waste waters wherein the solution has less than about 5 ppm, and preferably less than 2 ppm, metal ions.

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: Waste water from a laundry (1) is collected in a storage container (3), fluffs and textile sheddings are separated through filtering sieves (2). The volume of the container is set so that it may store the amount of waste water produced for example during two days. The waste water is supplied with a bio-reactor (4) that works in aerobic conditions. Air is lead into the bio-reactor (4) at its lower end (5), establishing aerobic conditions therein. The biologically considered water leaves the bio-reactor (4) at the top end (6) of the column-shaped bio-reactor (4) and is supplied to an active coal column that acts as an adsorber (7). The adsorptively purified water leaves the adsorber (7) packed with active coal through the duct (8), is collected in a storage container (9) and if required is returned through duct (10) to the laundry, if required after 5 to 20% fresh water are added.

Abstract: The process consists in passing the liquid to be purified and a superabsorbent, preferably of polyacrylic type, through a column, the upward speed of the liquid being chosen such that, in the column, the superabsorbent which is merely swollen is in a stationary dynamics regime, whereas the superabsorbent laden with polyvalent ions settles at the bottom of the column. Application to the treatment of the aqueous rinses of articles which have undergone a nickel-plating treatment.

Abstract: The instant invention relates to a novel process for the hydrolysis of the by-products produced during the manufacture of methyldichlorosilanes comprising combining the by-products with an aqueous medium, optionally comprising a surfactant, at a pH range of at least about 7 and at a temperature of above about 0.degree. C. to produce a solid material in which copper and other metals are retained in a solid phase thereby resulting in a product with a high copper content.

Abstract: The metal oxide media includes oxides and hydroxides of iron, and other metals. The material is derived from basic-oxygen steel-making process, and includes a high calcium content. The oxide surfaces facilitate the adsorption of phosphorus, and the increased pH facilitates the precipitation of calcium and other phosphates. The oxides are a catalyst for converting organic phosphorus to inorganic form. Limestone may be added to the oxides, to ensure a long-term source of calcium, and to maintain high pH for long periods.

Abstract: A process and system for removing heavy metals, fluoride, silica and other contaminants from large volumes of wastewater is disclosed. In the process, a wastewater stream containing the contaminant is treated with a chemical coagulant to create a particle having a diameter greater than 5 microns. Treated wastewater is passed through a microfiltration membrane which physically separates the metal contaminant particle from the wastewater. Commercially available microfiltration membranes having a pore size from 0.5 micron to 5 microns may be used. The treated wastewater flow rate through the microfiltration membranes can range from 700 gallons per square foot of membrane per day ("GFD") to 1500 GFD. Solids are removed from the membrane surface by periodically backflushing the microfiltration membranes and draining the filtration vessel within which the membranes are located. The dislodged solid material within the filtration vessel is flushed into a holding tank for further processing of the solids.

Abstract: Ozonolysis is an effective process for improving the quality of produced water. A process for reducing the concentration of water soluble organic materials dissolved in produced water consists of introducing into the produced water a sufficient amount of gaseous ozone by use of a means for maximizing the collision frequency of ozone gas and the produced water. The temperature of the produced water is between from about 80.degree. to about 180.degree. F. The process renders a water effluent with markedly reduced oil and grease content. The water effluent can be used on land as a drinking or irrigation water supply source and may be safely discharged into navigable waters.

Abstract: Arsenic and TOC are removed from drinking water or wastewaters by use of finely-divided metallic iron in the presence of powdered elemental sulfur or other sulfur compounds such as manganese sulfide, followed by an oxidation step. A premix may be produced for this process, by adding the iron, sulfur and oxidizing agent to water in a predetermined pH range. The iron and sulfur are mixed for a period of time dependent upon the temperature and pH of the water and the presence of complexing or sequestering minerals and organic acids in the water. An oxidizing agent is added to the mixture and agitating is continued. In a preferred embodiment the oxidizing agent is hydrogen peroxide. Water is decanted from the mixture after a sufficient reaction time, to produce a concentrated premix. This premix can be added to water intended for drinking or to industrial effluents containing toxic materials.

Abstract: An agent for recovering heavy metal cations from an aqueous effluent, including a silicate or aluminosilicate type compound, e.g. an alkali metal silicate or aluminosilicate, and a carbonate type compound, e.g. an alkali metal carbonate, and preferably a carrier such as a lay. The agent may also form a cation stabilizer. Said agent is useful for removing or stabilizing heavy metal cations in the water used for cleaning flue gases from waste incineration, particularly household refuse and industrial waste incineration.

Abstract: The invention relates to the treatment of waste water containing a harmful ion such as a heavy metal ion or fluorine ion by the coagulating sedimentation method using an inorganic coagulant such as an iron compound or an aluminum compound. After separating treated water from the sediment (sludge) in which the harmful ion is incorporated in insoluble form, the pH of a mixture of the sediment and water is suitably adjusted to cause elution of the harmful ion from the sediment. Then the sediment is separated from the eluate and reused as an inorganic coagulant. By reusing the sediment in this manner, the waste water treatment is accomplished without producing a large quantity of sludge and the consumption of inorganic coagulant and auxiliary chemicals can be greatly reduced, while the concentration of the harmful ion in the treated water becomes sufficiently low.