Abstract: Pollutants, such as heavy metals, phosphorus, and pathogenic organisms, are removed from water by adding a chemical coagulant to water within an enclosure. With mixing, coagulation and flocculation occur, and a floc containing the pollutant settles to the enclosure bottom; so the treated water above the floc is free from at least some of the pollutant. Some of the treated water is removed from the enclosure, and new water is added. The new water and the settled floc are mixed to resuspend floc components. The process is repeated until the floc no longer exhibits contaminant-removal capability. In an alternate system, a matrix element is deployed within the enclosure, which captures a portion of the floc that settles within the water column. Pollutants in new water added to the enclosure encounter these suspended floc particles and are subsequently removed from the water.

Abstract: A method for treating water includes directing untreated water into a mixing zone in a water treatment system and mixing the untreated water with a flocculating agent and a ballast to form a ballast-floc mixture. Thereafter, the ballast-floc mixture is directed to a settling zone where the mixture settles to form sludge. Treated water is discharged from the settling zone and the sludge is directed to a separator. The method further includes separating at least a portion of the ballast from the sludge and directing the separated ballast from the separator to the mixing zone. Finally, the sludge is directed from the separator to a sludge treatment reactor where at least some of the remaining ballast settles from the sludge and substantially ballast-free sludge is discharged from the sludge treatment reactor.

Abstract: A method of removing metal scale from surfaces that includes contacting the surfaces with a first aqueous solution of a chelating agent, allowing the chelating agent to dissolve the metal scale, acidifying the solution to form a precipitant of the chelating agent and a precipitant of the metal from the metal scale, isolating the precipitant of the chelating agent and the precipitant of the metal from the first solution, selectively dissolving the precipitated chelating agent in a second aqueous solution, and removing the precipitated metal from the second solution is disclosed.

Abstract: A process for removing phosphorus from wastewater wherein an iron or aluminum salt is added to the wastewater. The iron or aluminum salt results in the precipitation of certain iron or aluminum species that include phosphorus adsorption sites. These iron or phosphorus species are settled and become a part of sludge produced in the course of the wastewater treatment process. By recycling substantial portions of the sludge, the concentration of these iron or aluminum species in the wastewater is increased. This increased concentration results in the presence of large quantities of unused phosphorus adsorption sites that attract and adsorb phosphorus, resulting in phosphorus being removed from the wastewater.

Abstract: Presently no chemicals are added in the pulp/paper mills wastewater treatment. There is a loop hole with the Biological Oxygen Demand test utilized. Regulators depend on the Biological Oxygen Demand test. All mills are discharging raw untreated wastes high in Chemical Oxygen Demand, (COD), Total Organic Carbon, (TOC) and COLOR. Liquid Alum solution is added to raw influent. All electrical energy aerated systems are eliminated. All flows from sewers join prior to the entrance to clarifier. The continuous in-line pH controller is proprietary as well as the continuous in-line COD analyzer. Because mills wastewater is amphoteric, it is mandatory that the raw influent pH be adjusted to range of 5.7 to 6.0 for optimum removal efficiencies. Aluminum chloride, ferric chloride and ferrous sulfate may be replaced for alum with higher operating costs. The precipitate is thickened, dewatered and incinerated, and approximately 75% of the chemicals regenerated.

Abstract: Processes for removing oil from a solid wellbore material such as drill cuttings or water such as produced by a subterranean formation include contacting the solid material/water with an amino-substituted polymer such as chitosan and a halogenating agent. The oil separates from the solid material and becomes bound within a flocculated solid. The flocculated solid containing the oil subsequently may be combined with a solvent of the amino-substituted polymer. Further, the flocculated solid may be contacted with a reducing agent, converting the flocculated solid back into the amino-substitute polymer and forming an oil-phase separate from the solvent-phase. The oil-phase may then be separated from the solvent phase and recovered. The solvent in which the amino-substituted polymer is dissolved may be recycled for treating more solid material removed from the well bore.

Abstract: The invention concerns a water treatment method which consists in introducing coagulated water in a flocculation zone, to enable flocculation of microflocs in the presence and around a ballast; introducing the mixture in a decantation zone; separating the treated water in overflow and a mixture of sludge and the ballast in underflow; conveying at least part of said mixture to a sludge/ballast separating system and recycling into or upstream of the flocculation zone the ballast and part of the sludge introduced in said separation system.

Abstract: A method for recycling sludge during waste-water treatment firstly utilizes a process of chemical coagulation to produce sludge rich in copper ions. The sludge is then leached in a sulfuric acid storage tank with sulfuric acid of concentration 1-2N, whereby a extractive solution with copper enrichment 18-39 g/L and residues can be obtained. The extractive solution is then processed in a refrigeration crystallization tank to form copper sulfate crystals. Further, the residues produced are added into the coagulation tank as a coagulant in the process of chemical coagulation for wastewater treatment, thereby achieving a goal of zero sludge production.

Abstract: A two-step chemical precipitation process involving hydroxide precipitation and sulfide precipitation combined with “field separation ” technology such as magnetic separation, dissolved air flotation, vortex separation, or expanded plastics flotation, effectively removes chelated and non-chelated heavy metal precipitates and other fine particles from water. In the first-step, the non-chelated heavy metals are precipitated as hydroxides and removed from the water by a conventional liquid/solids separator such as an inclined plate clarifier to remove a large percentage of the dissolved heavy metals. The cleaned water is then treated in a second precipitation step to remove the residual heavy metals to meet discharge limits. In the second precipitation step, any metal precipitant more effective than hydroxide for metal precipitation can be used.

Abstract: Toxic waste waters polluted with high levels of chemical byproducts of various industrial processes (e.g., waste water held in industrial holding ponds) are treated using gas hydrate to extract and remove fresh water from the polluted water, thus reducing the volume of toxic waste water inventories. Extracting fresh water by forming and removing the hydrate raises the concentration of dissolved materials in the residual concentrated brines to levels at which the residual fluid is suitable for use as an industrial feedstock. Furthermore, so raising the concentration of the residual brine will cause certain mineral species to precipitate out of solution, which mineral species are separated from the fluid and may be put to other uses, as appropriate. Food products are also advantageously concentrated by means of gas hydrates.

Abstract: Processes for removing oil from a solid wellbore material such as drill cuttings or water such as produced by a subterranean formation include contacting the solid material/water with an amino-substituted polymer such as chitosan and a halogenating agent. The oil separates from the solid material and becomes bound within a flocculated solid. The flocculated solid containing the oil subsequently may be combined with a solvent of the amino-substituted polymer. Further, the flocculated solid may be contacted with a reducing agent, converting the flocculated solid back into the amino-substitute polymer and forming an oil-phase separate from the solvent-phase. The oil-phase may then be separated from the solvent phase and recovered. The solvent in which the amino-substituted polymer is dissolved may be recycled for treating more solid material removed from the well bore.

Abstract: A clarification system for fluids in which particles are separated from the fluid by flotation and in which the buoyant media inducing the flotation is recycled. Flotation can be assisted by a flotation assistance device, such as dissolved air flotation.

Abstract: Pollutants, such as heavy metals, phosphorus, and pathogenic organisms, are removed from water by adding a chemical coagulant to the water within an enclosure. The water and the coagulant are mixed, and coagulation and flocculation are permitted to occur. The mixing is stopped, and a floc is permitted to settle to the enclosure bottom. The floc contains the pollutant; so the treated water above the floc is free from at least some of the pollutant. At least some of the treated water is removed from the enclosure, and new water is added to the enclosure. The new water and the settled floc are mixed to resuspend components of the floc. The process is repeated for multiple iterations, until the floc no longer exhibits contaminant-removal capability, at which time the floc is removed from the enclosure.

Abstract: The invention relates to a method for treatment of water, permitting the physico-chemical treatment of water, including a ballasted flocculation stage using a granular ballast material with a density greater than water, followed by, a stage of gravity separation of the treated water and the flocculent mass, a stage of separation of the granular material, recycled for the flocculation stage and the muds. Said muds are sent to a stage for treatment of the muds, characterised in comprising a stage in which the functional mode passes from a mode using ballasted flocculation and gravity separation using coagulation and flocculation reagents to a mode functioning by simple gravity separation, without using coagulation and flocculation reagents. The passage from one mode to another is determined using at least one item of information on the water obtained at any stage of the treatment thereof or before said treatment.

Abstract: A method is provided for thickening sludge produced through a ballasted flocculation process. The sludge and granular material from the ballasted flocculation process are directed to a sludge separator where the sludge is separated from the granular material. Thereafter the separated sludge is sent to a degassing area and the sludge is degassed. A flocculating agent is mixed or injected into the sludge. The sludge is directed to a sludge thickener with a load at a sill calculated on the surface of the thickener greater than 200 kgMIS/m2/day. This process produces a thickened sludge having a concentration greater than 10 gm/I.

Abstract: Methods and apparatus for measuring sag properties of a drilling fluid using a rotary viscometer. An insert, or shoe, is placed at the bottom of the heat cup containing the fluid to be tested. A rotating cylinder is disposed within the fluid and solid particles are allowed to settle toward the bottom of the heat cup. The shoe incorporates a curved and inclined upper surface that directs the settled particles toward a well non-centrally located in the shoe. As the test is performed, fluid samples can be withdrawn from the well and analyzed. The samples can then be returned to the well and the test continued. The insert concentrates the settled solids into a single location, which increases the sensitivity of the test and provides a location for sample acquisition that is easily and repeatedly located, which allows for improved correlation with laboratory and flow loop results.

Abstract: The present invention is directed to a method and apparatus for the treatment of water and wastewater. In one embodiment, a method of treating water according to the present invention includes mixing sludge and precipitant with the water to be treated, mixing ballast with the water, and separating the water into treated water and sludge. Some or all of the separated sludge may be recycled for mixing with the precipitant and water to be treated.

Abstract: A two-step chemical precipitation process involving hydroxide precipitation and sulfide precipitation combined with “field separation” technology such as magnetic separation, dissolved air flotation, vortex separation or expanded plastics flotation, effectively removes chelated and non-chelated heavy metal precipitates and other fine particles from water. In the first-step, the non-chelated heavy metals are precipitated as hydroxides and removed from the water by a conventional liquid/solids separator such as an inclined plate clarifier to remove a large percentage of the dissolved heavy metals. The cleaned water is then treated in a second precipitation step to remove the residual heavy metals to meet discharge limits. In the second precipitation step, any metal precipitant more effective than hydroxide for metal precipitation can be used.

Abstract: The invention concerns an installation for measuring the concentration in dense granular material in a flow comprising a liquid, a dense granular material and suspended fine particles. The invention is characterised in that it comprises: at least a member for separating the dense granular material from the liquid and the suspended fine particles, at least a device for measuring (12, 12a, 13) at least a parameter representing the amount of separated dense granular material for a specific time interval T. Such an installation may be integrated in a ballasted-floc water treatment system.

Abstract: Water purification using organic salts. Feed water is mixed with at least one organic salt at a temperature sufficiently low to form organic salt hydrate crystals and brine. The crystals are separated from the brine, rinsed, and melted to form an aqueous solution of organic salt. Some of the water is removed from the aqueous organic salt solution. The purified water is collected, and the remaining more concentrated aqueous organic salt solution is reused.

Abstract: The invention relates to a process for the treatment of fly ash accumulating in the electro-filter of the soda recovery unit in a sulfate cellulose mill, the ash containing primarily Na sulfate, Na chloride, Na carbonate and K sulfate, to produce industrial raw materials, in which process the fly ash is dissolved in water, the carbonate present therein is broken down with hydrochloric acid to Na chloride, a sulfate precipitation chemical in chloride form is added, the sulfate precipitate obtained is separated from the solution, and the chloride-containing solution is recovered.

Abstract: A crystal substance formed by precipitating as fibrous aggregates by making a metal aliphatic carboxylate dissolve completely in pure water, stirring, and gradually cooling the resulting solution. A method of preparing the fibrous crystal aggregates. A material for recovering flowing oil and method of recovering flowing oil by using the fibrous crystal aggregates. A material for solidifying liquid hydrocarbon, waste tempura oil and edible oil and method of solidifying liquid hydrocarbon, waste tempura oil and edible oil by using the fibrous crystal aggregates. A method of preparing the solidifying material.

Abstract: A cost-effective method for reducing the dissolved sulfide content in a wastewater stream and thereby hydrogen sulfide emissions therefrom involving the steps of adding a transition metal salt to the wastewater stream at the upper reaches of a wastewater collection system prior to at least some hydrogen sulfide volatilization followed by addition of an oxidant to the wastewater stream to generate elemental sulfur and a transition metal salt which subsequently participates in additional hydrogen sulfide capturing steps, thereby also improving water quality and wastewater treatment plant operations.

Abstract: In the typical embodiments disclosed in the specification, a ballasted flocculation liquid treatment arrangement includes a mixing chamber in which liquid to be treated, flocculating agents and granular material are mixed. The mixture is supplied to the bottom of a flocculating chamber adjacent to the mixing chamber through an opening in a common wall between the chambers and is maintained in suspension in the flocculating chamber by turbulence generated by a rotating blade array. Ballasted flocs are transferred from the flocculation chamber to an adjacent sludge tank through a first opening in a common wall between them and liquid which contains lighter flocs is returned to the flocculation chamber through a second opening in the common wall. Liquid from the flocculation chamber passes upwardly through a turbulence control arrangement where flocs and particulates are substantially removed and into a clarification chamber where clarified liquid is passed over a weir to an outlet.

Abstract: In the typical embodiments disclosed in the specification, a ballasted flocculation liquid treatment arrangement includes a mixing chamber in which liquid to be treated, flocculating agents and granular material are mixed. The mixture is supplied to the bottom of a flocculating chamber adjacent to the mixing chamber through an opening in a common wall between the chambers and is maintained in suspension in the flocculating chamber by turbulence generated by a rotating blade array. Ballasted flocs are transferred from the flocculation chamber to an adjacent sludge tank through a first opening in a common wall between them and liquid which contains lighter flocs is returned to the flocculation chamber through a second opening in the common wall. Liquid from the flocculation chamber passes upwardly through a turbulence control arrangement where flocs and particulates are substantially removed and into a clarification chamber where clarified liquid is passed over a weir to an outlet.

Abstract: The invention concerns a flocculation-decantation method by ballasted flocs using a granular material and a step which consists in treating the sludge derived from flocculation-decantation in a circular grit trap wherein the auxiliary liquids tangentially injected into the sludge substantially in the same direction as the latter. The invention also concerns a circular grit trap with a cylindrical part of diameter D tangentially supplied with the suspension to be treated and a conical part and provided with a cylindrical chamber injecting wash-water provided at the conical part outlet and having a diameter D′ ranging between 0.35 D and 0.65 D, said cylindrical chamber having at least a tangential supply of auxiliary liquid along the same feeding direction as said tangential supply of the suspension to be treated.

Abstract: A process for forming small micron-sized (1-10 &mgr;m) protein particles is provided wherein a protein, a solvent system for the protein and an antisolvent for the protein solvent system are contacted under conditions to at least partially dissolve the protein solvent system in the antisolvent, thereby causing precipitation of the protein. The solvent system is made up of at least in part of a halogenated organic alcohol, most preferably 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Preferably, a solution of the protein in the solvent system is sprayed through a nozzle into a precipitation zone containing the antisolvent (preferably CO2) under near- or supercritical conditions.

Abstract: A conditioned alum-type water treatment residual is disclosed. A process for the conditioning of alum-type water treatment residual is likewise disclosed. The process includes dewatering the alum-type water treatment residual and conditioning by at least one method selected from the group consisting of conditioning by aging and physically turning periodically. A blended topsoil comprises conditioned alum-type water treatment residual and at least one topsoil component. A process for producing a blended topsoil with alum-type water treatment residual is disclosed. The alum-type water treatment residual is dewatered, conditioned by aging or turning periodically, and blended with topsoil components to produce a blended topsoil. The blended topsoil contains up to 50% alum-type water treatment residual by volume and preferably contains up to 30% alum-type water treatment residual by volume.

Abstract: Alum, used as a coagulant in water treatment, is recovered from clarifier sludge by adjusting the pH of the sludge downward to produce an aqueous clarifier sludge solution, and contacting the aqueous clarifier sludge solution with one side of a semi-permeable cation exchange membrane while contacting the other side of the membrane with an acidic sweep solution. By virtue of the Donnan co-ion exclusion phenomenon, aluminum ions, which are trivalent, pass readily through the membrane, in preference to divalent and monovalent cations, and consequently heavy metal carryover is relatively low. Organic matter carryover is substantially excluded, and consequently, the recovered alum can be reused without the potential for trihalomethane formation. The reactor is preferably in the form of a stack of spaced membranes, with the aqueous clarifier sludge solution and the acid sweep solution flowing through alternate spaces. The same process can be used for recovery of ferric iron coagulants.

Abstract: A system and process for agglomerating and processing carbonaceous fines is provided. The process includes powdering the carbonaceous fines, mixing the powdered carbonaceous fines with an organic liquid creating a slurry, adding a predetermined amount of an aqueous electrolyte to the slurry creating agglomerated particles, settling the large agglomerated particles resulting in a settled mixture of agglomerated coal fines and reagent liquor, and separating the agglomerated coal fines from the reagent liquor.

Abstract: This invention relates to a process for removing sulphates and calcium from a water stream which includes the steps of: combining the water stream and an amount of amorphous aluminum trihydroxide (Al(OH)3); allowing the formation of ettringite (3CaO.Al2O3.3CaSO4.31/32H2O) as a precipitate; and removing the precipitated ettringite from the water stream.

Abstract: Process employing the technique of ballasted flocculation with a step of injection, into the liquid to be clarified, of a ballast consisting of a granular material and of a polymer, followed by a flocculation step which leads to the formation of a ballasted floc, and by an accelerated settling step, said ballast being recirculated into the flocculation step, either as it is or after cleaning, wherein said process includes two recirculation regimes: a high-energy regime ensuring draw-off of the ballast contained in the ballasted floc, removal of the floc in the form of sludge and recycling of the cleaned ballast into the flocculation unit and, a low-energy regime ensuring transfer of the ballasted floc into the flocculation unit as long as the ballast ratio in the flocculator is greater than a predetermined level, this low-energy regime remaining in service while the high-energy regime is being put into action, but then being shut down during the operation of the high-energy regime, the two systems being emp

Abstract: Provided herein is a process for treatment of solutions which contain ferrous, ferric and soluble manganese species which process comprises addition of an oxidizing agent to such a solution to cause formation of manganese dioxide particles and adding manganese dioxide seed particles so as to cause nascent manganese dioxide agglomerates formed from the action of the addition of the oxidizing agent on the soluble manganese species to adhere to the manganese dioxide seed particles. By a process according to the invention, it is possible to effectively remove the soluble manganese species as solid manganese dioxide by having effective control over the size of the manganese dioxide particles to enable their subsequent removal using ordinary filtration techniques.

Abstract: The present invention provides a crystallization process for removing fluoride from waste water. Fluoride-containing waste water is introduced into a fluidized bed crystallizer provided with a carrier. A water soluble sodium reagent and a water soluble aluminum reagent are added into the fluidized bed crystallizer to form crystallized cryolite (Na3AlF6) onto the carrier. The treated waste water is separated from the fluidized bed crystallizer to obtain a primary treated water. The formed cryolite is in the form of crystals, which contain about less than 10% water, and is very convenient for re-utilization.

Abstract: A method for separating benzene from a hydrocarbon mixture containing benzene and at least one other organic material is carried out by treating the hydrocarbon mixture with at least one cyclodextrin to form complexes of the cyclodextrin with at least a portion of the benzene present in the hydrocarbon mixture. The cyclodextrin-benzene complexes then are separated from the hydrocarbon mixture.

Abstract: A method of purifying an aqueous liquid stream is provided, wherein the liquid stream is pressurized and contains proteinaceous materials, such as blood, and suspended solids, comprising the introduction of carbon dioxide into the liquid stream in a manner to reduce the pH of the liquid stream sufficient to cause coagulation ofthe proteinaceous materials. Specifically, it is intended that the pH of the liquid stream is reduced to a level below the isoelectric point of the proteinaceous materials, preferably at a level below pH 4.5. In a preferred method, the liquid stream is moved by a dissolved gas pump, wherein the carbon dioxide is introduced into the dissolved gas pump, and wherein a first portion of the gas is caused to dissolve within the liquid stream, and a second portion of the gas is caused to entrain within the liquid stream in the form of micro-fine bubbles.

Abstract: A process for removing fluoride from wastewater is presented. Calcium (or magnesium), sodium and aluminum reagents are added into a fluidized bed crystallizer to remove most of the fluoride in wastewater. The remaining fluoride is removed by aluminum hydroxide. Alternatively, two fluidized bed crystallizers are used in series to treat the fluoride-containing wastewater: in the first fluidized bed crystallizer, calcium (or magnesium), sodium and aluminum reagents are used to treat the wastewater which contains high concentrations of fluoride, so that the fluoride concentrations thereof are largely reduced. Then, in the second fluidized bed crystallizer, a calcium reagent is added to further remove fluoride therein.

Abstract: Process for the physico-chemical treatment of effluent, especially of surface water intended for consumption, comprising the successive steps of coagulation, flocculation and settling, a contacting mass being introduced into the water coming from the coagulation step, and therefore during the flocculation step, and this contacting mass consisting of part of the densified sludge resulting from the settling step and recycled in the flocculation step, this process being characterized in that at least part of the polyelectrolyte ensuring flocculation is injected into a sludge-recirculation circuit.

Abstract: A process is disclosed for the physico-chemical treatment of effluent, especially surface water intended for consumption, the process includes the successive steps of coagulation, flocculation and settling, wherein, during the flocculation step, a ballast is introduced into the sludge, the function of which ballast is to make the sludge heavier. The contacting mass used during this flocculation step consists of part of the densified sludge resulting from the settling step and continuously recycled in the flocculation step, without any treatment.

Abstract: A method of treating cleaning solvent used to clean mechanical parts. The method includes adding to the cleaning solvent a treating composition selected from the group of C.sub.5 -C.sub.14 alcohols, C.sub.2 -C.sub.8 dials, C.sub.10 -C.sub.14 polyols, and C.sub.4 -C.sub.14 glycol ethers, and mixtures thereof. A further embodiment includes the foregoing plus adding a clarifying agent from the group of aromatic, aliphatic and alkaryl sulfonic acids and sulfonic acid salts, esterified polyols, and alkyl phenol formaldehyde resins capped with alkoxy groups. The solvent is vaporized and condensed to effect recycling thereof without adding substituted quantities of treating composition to the solvent.

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 is proposed for the contiuous determination of gaseous oxidation products from industrial process, drinking and/or waste water, particularly for determining the TOC value, at least the organically bound carbon contained in a test solution to be investigated being oxidatively transformed and the gaseous oxidation products are supplied to a measuring unit, where at least the organically bound carbon is detected, the test solution being continuously pumped into a microreactor, where it is heated to a predetermined temperature and the organic compounds in the test solution are continuously oxidatively transformed under a temperature and pressure increased in a defined manner.

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 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: 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.

Abstract: A sedimentation device for treating water and wastewater utilizing differential sedimentation and recirculation in an internal recirculation reactor with an upflow zone and a downflow zone within a settling tank. Inert particles are added to the internal recirculation reactor to increase the growth rate of forming flocs and increase the differential sedimentation of the flocs in the downflow zone.

Abstract: A process for the treatment of aqueous acidic liquors containing dissolved aluminum and/or iron compounds to produce an aluminum and/or iron sulfate water-treatment product is characterized by the combination of steps comprising contacting the liquor with a basic material capable of reacting with the dissolved aluminum and/or iron compound to precipitate aluminum and/or iron values, separating the precipitate in the form of a cake or slurry from the remaining liquor, treating the cake or slurry with sulfuric acid to re-dissolve aluminum and/or iron values and to produce a solution of aluminum and/or iron sulfate and separating suspended solid matter from the solution. The liquor may be a waste product from industrial processes or may be a mine effluent and the process avoids the need to dispose of these to waste.

Abstract: An untreated flow of waste water is normally introduced into a plain sedimentation unit during plain sedimentation periods to separate it into sand and a flow treated by plain sedimentation. During other periods, for example periods of heavy rain, a coagulating agent, ballast sand and a flocculating agent are introduced. The coagulated flow is passed into a maturation intermediate area and then, with substantially all the sand and colloids of particles attached to it, into the plain sedimentation unit. Here effluent is separated by plain sedimentation and evacuated and sludge made up of the sand and the adhering colloids and particles is extracted and evacuated via an extraction system and the sand outlet channel of the plain sedimentation unit. The sludge is collected, the ballast sand is separated from it to be recycled into the sand injection area and the sludge and excess sand are extracted.

Abstract: Alum process residues (APR) are used to remove colored contaminants from waste waters. In addition, in accordance with the invention, up to 0.1% by weight of alum and up to 5 ppm of a polyelectrolyte polymer is added to improve color removal, turbidity removal and the settling rate. The resultant APR-alum-polymer mixture together with contaminants in the waste water settles rapidly, reducing the costs of the color removal process.

Abstract: There is provided a process for converting a silver-mercapto-s-triazine precipitate to a solid containing silver and a solution containing mercapto-s-triazine by contacting the silver-mercapto-s-triazine precipitate with one or more reducing agents. In preferred embodiments, at least one of the reducing agents has a redox potential more negative than about -0.9 V vs. Normal Hydrogen Electrode, NHE.