Abstract: Systems and methods for polymer addition control for sludges from water and wastewater treatment. In a treatment process where flocculating agents are used to promote solids aggregation, intrinsic physical properties of the liquid rich stream following separation may be continuously measured in order to control or optimize the amount of flocculating or treatment agent that is added to the process. These intrinsic physical properties may include, for example, the flocculating suspension or network strength. By determining the floc strength using various treating agent dosages, a optimum treating agent dose can be determined. The optimum treating agent dosage is the minimum in a floc strength to polymer dose curve.

Abstract: A method for purifying a spent acid catalyst from an acid catalyzed chemical reaction that generates a mixture of a product, spent add and tar, includes the steps of separating the mixture of product, spent acid, and tar into a product fraction and a spent acid fraction, said spent acid fraction comprising a mixture of spent acid and tar, and separating the spent acid fraction, by flotation separation, centrifugation, or liquid-liquid coalescence, into a tar fraction and a de-tarred spent acid fraction. The fluidized tar and the de-tarred spent acid can each be further processed to produce concentrated acid.

Abstract: The invention includes a method for demulsification of water-in-oil emulsions, oil-in-water emulsions, and mixtures of water-in-oil and oil-in-water emulsions by oscillatory mixing of the emulsions.

Abstract: A method of treating an oil-containing waste water includes adding, where the waste water has been adjusted to have a pH between eight and twelve and have a temperature not higher than 50° C., a high-cationic flocculant consisting of a high-molecular material selected from among acrylamide-quaternized or salified dimethylaminoethyl acrylate or methacrylate copolymer, and acrylamide-quaternized or salified dimethylaminoethyl acrylate or methacrylate-acrylic acid copolymer, and which constitutes a plurality of polymerized units at least 60 mol % of which have respective cationic functional groups, to the waste water, such that a concentration of the flocculant in the waste water falls between 100 mg/L and 1,000 mg/L, so that at least one fouling component dispersed in the water is flocculated to form a sludge consisting of flocks of the at least one fouling component and thereby separate the at least one fouling component and the water.

Abstract: A powered in-line blender for mixing additives to sludges or other flowable liquid/solid mixtures. The blender is particularly useful in a method of blending polymer to municipal sewage sludges to improve the dewatering characteristics, and thus improving total costs for dewatering, handling, and disposal.

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: Hot water pipes, in areas with hard water, tend to fill with scale until they no longer pass enough water. De-scaling water pipes with acid is dangerous, expensive and damages the pipes. Ion exchange and reverse osmosis water softeners eliminate scale buildup in pipes, but are expensive. This invention is a means of keeping the scale precipitate, created when water is heated, inside the water heater by passing the hot water through a removal medium where the scale sticks to the surface. The removal medium can be placed inside the water heater or in a separate tank connected to the water heater; both configurations remove the precipitate from hot water; both save hot water pipes from scale accumulation.

Abstract: Methods of treatment of fluids produced by an oil or gas well following a stimulation operation, allowing separation from the fluids and re-injection of oil and gas hydrocarbons in a production pipeline under pressure, and allowing achievement of suitable quality for the residual fluids compatible with their rejection, for example into the sea, including the following three elements; neutralization of the fluids by mixing with a high pH chemical, until the resulting pH reaches a level compatible with the equipment and pipes; use of optimized emulsion breakers in a phase separator, selected for best results with the fluids produced by the well, to accelerate the separation of oil from the fluids, and to lower the residual oil content in the fluids to levels compatible with environmental regulations; and use of a multi-phase pump to pump the oil and gas hydrocarbons produced and reinject them in a pipeline under pressure.

Abstract: The levels of iron sulfide present in a conduit, such as a pipeline, are reduced by contacting the conduit, on an inner surface, with a composition obtained from an aqueous solution containing at least one compound of Formula (I) and at least one amine or corresponding ammonium derivative in the presence of a solvent, wherein X is an anion of valency n. Preferably, the pH of the solution is about 8. Alternatively, the method employs a composition comprising tris(hydroxymethyl)phosphine (TRIS) and at least one amine or corresponding ammonium derivative. The amine preferably is ammonia or a primary alkylamine. The compositions readily complex and thereby dissolve deposits of iron(II) sulfide, removing them from the conduit.

Abstract: A process for removing metal sulfates from dilute aqueous solutions in which a conductivity control solution is injected into the stream. The solution is selected to increase the conductivity of the stream to a value wherein the ion state of each metal is then modified by passing the stream between electrodes of each pair of an array of pairs of electrodes. A voltage is imposed across each pair of electrodes, selected according to a target ion state for each of the various contaminants. The pH of the stream is then increased to a value where precipitate of metal hydroxide of the metal sulfates are formed. The precipitated metal hydroxide is then removed from the stream leaving a reduced amount of sulfate ions.

Abstract: A method of purifying wastewater as a fluent coming either from industrial plants or from municipal sewage runs. The method includes the steps of running the wastewater as a fluent into a headworks where some preliminary treatment takes place. From there the fluent is passed into a primary reservoir. The primary reservoir analyzes the fluent as to certain control parameters such as pH, dissolved oxygen and/or dissolved solids. Thereafter the fluent flows into a primary reactor having a plurality of electrolytic cells therein. While in that reactor the fluent is subjected to electrical contacts which are located at the bottom and the top of the reactor. The effluent from the primary reactor passes through a ratio weir into a secondary receptor. The secondary receptor contains sensors for the measurement of control parameters such as pH, DO (dissolved oxygen TDS (total dissolved solids) and chlorine. Thereafter, the fluent is passed to a filtering device.

Abstract: A product and method for the removal of pollutant heavy metals from aqueous solutions which precludes the end user from storing, handling, feeding and controlling hazardous soluble sulfide materials. The product is a slurry which includes a mixture of a liquid medium and an essentially insoluble salt wherein the salt is the reaction product of heavy metal ions, preferably selected from Mn++ ions, Fe++ ions, and Fe+++ ions, and sulfide ions derived from soluble sulfide sources such as sodium sulfide, hydrogen sulfide, and sodium hydrosulfide. Addition of the subject slurry to a wastewater stream will effect the precipitation of heavy metals with lesser equilibrium sulfide ion concentrations than that of the essentially insoluble salt. Solids collected by this method may be returned to subsequent wastewater streams for additional removal of heavy metals by any excess heavy metal sulfide salt.

Abstract: The invention is directed to a method for flotation separation. The method has the steps of feeding an influent stream containing liquids and solids to a vessel, while removing clarified liquid at the same time as the feeding process. The method employs a step for emptying the solids from the vessel based on the solids having formed a float blanket of a predetermined depth. The solids are removed from the vessel through a bottom nozzle as opposed to being skimmed off the top surface with mechanical separators. The depth of the float blanket can be monitored. Once it is determined that the float blanket has reached the predetermined depth, the feed to the vessel is stopped and the vessel is emptied of liquids and solids through a suitable outlet other than the feed inlet, by an arrangement of valves and lines.

Abstract: Systems and methods for polymer addition control for wastewater treatment. In a water treatment process where flocculating agents are used to promote solids aggregation, intrinsic physical properties of the liquid rich stream following separation may be continuously measured in order to control or optimize the amount of flocculating or treatment agent that is added to the process. These intrinsic physical properties may include, for example, the viscosity or the density. By continuously measuring an intrinsic physical property of the liquid rich stream, additional tracing compounds may not need to be added to the water treatment system. The treatment process may also include a holding tank, or a device that separates the entering water into two or more streams, such as a liquid stream and a biosolid stream.

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: A method and apparatus for treating heavy-metal-containing wastewater using a sulfidizing agent. Sulfidizing treatment is carried out by adding a sulfidizing agent to heavy-metal-containing wastewater, while detecting hydrogen sulfide gas generated from the wastewater, such as to maintain a state in which hydrogen sulfide gas is just starting to be generated from the wastewater. When separately recovering each of a plurality of metals from wastewater in which are mixed ions of the plurality of metals, there is repeated for each of the metals a process in which the acidity of the wastewater is adjusted to within a range suitable for the metal to be separated out and recovered, a sulfidizing reaction is carried out on that metal, and the metal sulfide produced is precipitated and filtered off.

Abstract: There is a process for removing by-product tar during the manufacture of isopropyl alcohol. The process comprises the following: a) reacting propylene with concentrated sulfuric acid and water to form isopropyl alcohol and a spent acid having a by-product tar; b) capturing at least a portion of the isopropyl alcohol; c) contacting the spent acid with a gas in bubble form; d) allowing a least a portion of the tar to separate from the remainder of the spent acid to form a layer of tar and a layer of cleaned acid solution; e) capturing the tar; and h) recycling the cleaned acid solution to step a) as a source of sulfuric acid. There is also a process for removing by-product tar during the manufacture of methyl ethyl ketone. The process is substantially the same except that 1-butene is substituted for propylene. There is also a process for removing tar from a spent acid.

Abstract: A system is provided for removing dissolved metals from industrial wastewater by electrocoagulation. The system includes an electrocoagulation reactor with a DC power supply having an insulation support enclosure with positive and negative electrode plates disposed thereon. The electrode plates are insulated for each other but remain in direct contact with the wastewater as it flows between the electrodes. The DC power supply induces opposite charges on alternate electrodes thereby generating an electric field between adjacent electrodes to cause the electrodes to ionize and go into solution for interaction with the contaminants in the wastewater as it flows through the reactor. The reactor is housed in a pressure vessel container so the exterior pressure on the reactor is higher than its internal pressure preventing leakage of fluids and oxygen and hydrogen gases produced in the reactor by decomposition of water.

Abstract: A process for treating liquid septage and other biosolids having the steps of placing a known amount of liquid septage in a tank, mixing in a sufficient quantity of alkaline material to raise the pH to a desired level, flocculating the septage, storing the pH adjusted septage for a predetermined period of time, thickening the septage, de-watering the septage, and pasteurizing the resultant liquid effluent and de-watered solids cake. The process for treating liquid septage and biosolids disclosed by the current invention meets the Class A vector attractant reduction and pathogen reduction requirements mandated by the U.S. EPA. The end product of septage and other biosolids treated using the process disclosed by the current invention can be sold as fertilizer, and utilized without any additional permits.

Abstract: A method of treating an electroless plating waste is provided. The waste is contained and an ability of a reducing agent to reduce a metal of the waste is decreased, for example by adding a stabilizing chemical or by exposing the waste to an anode to which a positive voltage is applied. Poisonous and explosive gases evolve from the waste, which are vented. Upon completion, the waste is drained.

Abstract: The invention includes a method for demulsification of water-in-oil emulsions.

Abstract: Systems and methods for polymer addition control for sludges from water and wastewater treatment. In a treatment process where flocculating agents are used to promote solids aggregation, intrinsic physical properties of the liquid rich stream following separation may be continuously measured in order to control or optimize the amount of flocculating or treatment agent that is added to the process. These intrinsic physical properties may include, for example, the flocculating suspension or network strength. By determining the floc strength using various treating agent dosages, a optimum treating agent dose can be determined. The optimum treating agent dosage is the minimum in a floe strength to polymer dose curve.

Abstract: A system and method for dewatering a continuous stream of slurry at high flow rates demonstrates enhanced efficiency, economy and ease of operation. A stream of slurry is subject to continuous or continual measurement of flow rate and pulp density and the measurements are used to control the rate of addition of a flocculating agent to the slurry. The flocculated slurry is delivered to a dewatering unit where it is passed through a diffuser and evenly delivered to a tracking screen for filtering solids from a liquid filtrate. The pulp density of the filtrate may also be measured and used to control addition of a flocculating agent. The tracking screen is adjusted to achieve an angle of repose suited to the particular composition of the filter cake. The diffuser has a base having a horizontal section aspect ratio of from about 1:1 to about 4:1 and continuously changing vertically into an upper portion having a horizontal section with an aspect ratio of from about 40:1 to about 100:1.

Abstract: A system for removing fluoride from wastewater is provided. The system comprises a reaction tank for processing said wastewater by adding calcium salts, a filtration tank for removing the precipitated fluoride formed in the reaction tank, a single fluoride electrode disposed at the reaction tank for measuring a concentration of fluoride in the influent wastewater and providing an output signal, and a programmable controller for controlling addition of said calcium salts into said reaction tank. The programmable controller defines a setpoint of fluoride concentration in the reaction tank and automatically controls addition of calcium salts based on the setpoint and the output signal provided by the single fluoride electrode. A method of removing fluoride from wastewater is also provided.

Abstract: An apparatus for treating wastewater including a physical-chemical reactor; a chemical supply operably connected to the physical-chemical reactor; a clarifier operably connected to and located downstream of the physical-chemical reactor; a ballast recirculation line operably connected between the clarifier and the high rate physical-chemical reactor; and a control system that directs a) influent into 1) the clarifier but not the physical-chemical reactor when flow or pollutants of the influent is within a selected low range and 2) the physical-chemical reactor and then into the clarifier when the flow/pollutants of influent is within a selected higher range and b) internally generated ballast into the physical-chemical reactor through the ballast recirculation line when the pollutants and/or flow is within the selected higher range.

Abstract: Systems and methods for polymer addition control for wastewater treatment. In a water treatment process where flocculating agents are used to promote solids aggregation, intrinsic physical properties of the liquid rich stream following separation may be continuously measured in order to control or optimize the amount of flocculating or treatment agent that is added to the process. These intrinsic physical properties may include, for example, the viscosity or the density. By continuously measuring an intrinsic physical property of the liquid rich stream, additional tracing compounds may not need to be added to the water treatment system. The treatment process may also include a holding tank, or a device that separates the entering water into two or more streams, such as a liquid stream and a biosolid stream.

Abstract: There is a method for which a sewage sludge is permitted to flow from a first connecting region 21 to a treatment device, which works with rotation and stresses the sewage sludge with severing parts, and from the treatment device to a second connecting region 1. It is desirable to improve the continuity to the operation and to attain a decisive increase in the disintegration. This is achieved by using a rapidly rotating pipe-head formation, which has a head 6 with radial openings 10 and radial wings 4, for the mechanical disintegration of biogenic sewage sludge. The edges of the openings exert a shear effect, while the wings exert an impact effect and the combination of these two actions, in conjunction with the rapid rotation, brings about the improvement in the disintegration.

Abstract: A process and apparatus therefore in which a sludge treatment stage 24 is controlled in response to the density or solids content of the sludge includes flowing sludge along a flow line 1 towards the treatment stage, taking a sample from the flow line 1, degassing the sample to produce a degassed sample, measuring the density or solids content of the degassed sample, and utilizing the measured degassed density or solids content of the degassed sample for controlling the treatment stage 24.

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: The present invention provides a method for chemical addition utilizing adaptive process control optimizations having a combination of expert system(s), neural network(s) and genetic algorithm(s).

Abstract: The invention relates to a process for dewatering sewage sludges using plate filters, wherein the flocculated sewage sludge treated by means of organic polymer flocculation aids and optionally other auxiliary agents is separated from the major amount of water of the flocculated sewage sludge on a plate filter by means of hydrostatic filtration, whereafter the partially dewatered sewage sludge is subjected to pressure filtration. The plate filters employed have filtrate outlet systems permitting filtrate discharge at a flow rate of 1.0 m/s at maximum. By conducting the process in this way, the dewatering capacity is substantially increased.

Abstract: A water treatment method uses a removable, disposable cartridge having an internal mesh structure. A disposable heater heats water fed to the cartridge. Precipitated solids collect on the mesh surface provided temperature and residence times are appropriately maintained. The heat breaks down the bicarbonate hardness of the water thereby depositing carbonates on the mesh surface and heavy metals will be codeposited due to the resultant change in pH. The cartridge has a head-space for collecting entrained gases such as volatile organic compounds, chlorine and air. Water sterility is achieved by heating the water over an appropriate period of time. Turbidity is removed within the cartridge due to settling induced by the low fluid velocity controlled by a controller and by a filter provided at the outlet of the cartridge. The filter will become blocked when bicarbonate hardness is carried over forcing a user to replace a spent cartridge.

Abstract: A system is provided for removing dissolved metals from industrial wastewater by electrocoagulation. The system includes an electrocoagulation reactor with a DC power supply having an insulation support enclosure with positive and negative electrode plates disposed thereon. The electrode plates are insulated for each other but remain in direct contact with the wastewater as it flows between the electrodes. The DC power supply induces opposite charges on alternate electrodes thereby generating an electric field between adjacent electrodes to cause the electrodes to ionize and go into solution for interaction with the contaminants in the wastewater as it flows through the reactor. The reactor is housed in a pressure vessel container so the exterior pressure on the reactor is higher than its internal pressure preventing leakage of fluids and oxygen and hydrogen gases produced in the reactor by decomposition of water.

Abstract: Compositions of aluminum chlorohydrate and high molecular weight branched epichlorohydrin amine condensate polymers are applied to waste liquids, such as pulp and paper mill effluents having a lignin content, to reduce true color. The branched epichlorohydrin amine condensate polymer is branched using branching agents which result in a molecular weight greater than about 300,000 and permit solubility. When applied to waste liquids, the high molecular weight branched epichlorohydrin amine condensate polymer and aluminum chlorohydrate react with the lignin components in the waste liquid to form an insoluble agglomerate thus reducing the true color of the waste liquid. The resulting agglomerate, including the colored lignin, may be filtered from the waste liquid.

Abstract: The invention provides finely divided, substantially crystalline particles of budesonide characterized in that they are substantially smooth and having a BET value of from 1 to 4.5 m2/g, a process for their preparation, a pharmaceutical composition comprising said particles, the use of said particles in the treatment of and in the manufacture of a medicament for use in the treatment of respiratory disorder, and a method of treatment of respiratory disorders by administration of said particles to a host in need of such treatment.

Abstract: A process for removing metals from wastewater, which comprises the following: measuring the flow rate and oxidation reduction potential of wastewater as it is fed into a first treatment tank, adjusting the pH of the wastewater, adding a first liquid elixir to the wastewater to react with at least one metal in the wastewater to cause it to either precipitate out of solution, or convert into a form that will allow it to be precipitated out of solution by a second liquid elixir, and to bond with the metal to prevent it from re-dissolving back into solution, adding a second liquid elixir to the wastewater to react with at least one metal in the wastewater to cause it to precipitate out of solution, and to bond with the metal to prevent it from re-dissolving back into solution, feeding the wastewater into a second treatment tank, mixing a third liquid elixir and a fourth liquid elixir into the wastewater to flocculate and/or coagulate the precipitated metals, and separating the flocculated and/or coagulated precip

Abstract: A water treatment method uses a removable, disposable cartridge having an internal mesh structure. A permanent heater heats water fed to the cartridge. Precipitated solids collect on the mesh surface provided temperature and residence time are appropriately maintained. The heat breaks down the bicarbonate hardness of the water thereby depositing carbonates on the mesh surface and heavy metals will be codeposited due to the resultant change in pH. The cartridge has a head-space for collecting entrained gasses such as volatile organic compounds, chlorine and air. Water sterility is achieved by heating the water over an appropriate period of time. Turbidity is removed within the cartridge due to settling induced by the low fluid velocity controlled by a controller and by a filter provided at the outlet of the cartridge. The filter will become blocked when bicarbonate hardness is carried over forcing a user to replace a spent cartridge.

Abstract: The present invention relates to a sludge treatment plant in which sludge is flocculated and then dewatered to form a cake and a reject liquor is modified by recycling 3 to 40% of the reject liquor into the sludge immediately before the dewatering process.

Abstract: The invention relates to an apparatus for separating water-containing solvent mixtures having two or more phases, using one or two gravitational separators (4, 16) and to the use of this apparatus, and also to a process for separating water-containing solvent mixtures having two or more phases. Using the novel apparatus it is possible to separate even small-density-difference solvent mixtures having two or more phases. To this end, a coalescence separator (1) has been provided upstream of the first gravitational separator (4).

Abstract: The present invention relates to a method for the continuous separation of caesium, strontium and transuranium elements contained in sodium waste which comprises the use of NaTPB, and to a device for the implementation of this method.

Abstract: A process for optimizing the rate of oxidation using halogen, e.g. chlorine donors to prevent the accumulation of undesirable chlorinated by-products. The feed rate of a chlorine donor is controlled for maintaining a desired ORP. The amount of free halogen is reduced and the ORP range expanded by addition of an effective amount of a coagulating agent. The rate of oxidation is sufficient to prevent the accumulation of the undesirable by-products. Treatment removes the by-products from the water and surrounding air by maintaining continuous breakpoint halogenation conditions.

Abstract: A method to treat wastewater brines to remove the salts prior to discharge. The method includes evaporating the water component of the pretreatment effluent into the atmosphere.

Abstract: A process for optimizing the rate of oxidation using a combination of halogen, e.g. chlorine donors and peroxygen, e.g. potassium monopersulfate. The peroxygen compound elevates the oxidation-reduction potential of the body of water being treated. Simultaneously, a halogen donor is added to the body of water to maintain a PPM level of free halogen sufficient to insure sanitization. The amount of free halogen is reduced and the ORP effective range expanded to 700-850 mv by addition of an effective amount of a coagulating agent. The feed rates and concentrations of both oxidizers are optimized so as to achieve and maintain the targeted parameters. A high level of oxidation is maintained which removes by-products from the water and surrounding air.

Abstract: A wastewater treatment system and process for removal of radioactive particulates includes continuous monitoring of charged particles and the addition of chemicals to coagulate and cause removal of the particulates from the wastewater.

Abstract: The invention relates to a method for treating and conditioning circulated rolling oil, comprising removing dirt and abrasion particles from the returned rolling oil by filtration, feeding filter aids in a controlled manner, and adjusting an electric conductivity preventing electrostatic charging in the purified rolling oil. So that conductivity additives can be omitted, a flocculating agent is employed as the filter aid, and the amounts in which the agent is added depends on the residual contamination remaining in the filtrate, so that a preset minimum conductivity caused by the remaining residual contamination is preserved in the filtrate.

Abstract: A process is provided to create a treated recycle stream through pre-treatment and solids separation for reuse in animal feeding operations without odors and creates a treated liquid effluent that can be stored for reuse, or can be land applied without odors and is free from pathogens and nutrients. Additionally the methods describe a means of converting animal manure to organic fertilizer and removing nutrients from the liquids to create a feed supplement from biomass. The organic fertilizer is non-leaching and free from pathogens. The entire process is accomplished in a reduced footprint from other treatment processes and allows waste ponds to be removed from service.

Abstract: The invention provides finely divided, substantially crystalline particles of budesonide characterized in that they are substantially smooth and having a BET value from 1 to 4.5 m2/g, process for their preparation, a pharmaceutical composition comprising said particles, the use of said particles in the treatment of and in the manufacture of a medicament for use in the treatment of a respiratory disorder, and a method of treatment of respiratory disorders by administration of said particles to a host in need of such treatment.

Abstract: In a waste water treatment apparatus, sludge settled in a settling tank is treated by being introduced (returned) into a return sludge reaction tank having a settling section in its rear portion. Therefore, unreacted chemicals contained in the sludge that has settled in the settling tank can be utilized in the return sludge reaction tank. Therefore, the unreacted chemicals are not discharged as sludge. Accordingly, as compared with the conventional treatment method of discharging a sludge from the settling tank, it is possible to reduce the amount of generated sludge remarkably and consequently, reduce a sludge disposal fee, the use amount of slaked lime, and a running cost such as maintenance cost of a dehydrator.

Abstract: A system and method for dewatering a continuous stream of slurry at high flow rates demonstrates enhanced efficiency, economy and ease of operation. A stream of slurry is subject to continuous or continual measurement of flow rate and pulp density and the measurements are used to control the rate of addition of a flocculating agent to the slurry. The flocculated slurry is delivered to a dewatering unit where it is passed through a diffuser and evenly delivered to a tracking screen for filtering solids from a liquid filtrate. The pulp density of the filtrate may also be measured and used to control addition of a flocculating agent. The tracking screen is adjusted to achieve an angle of repose suited to the particular composition of the filter cake. The diffuser has a base having a horizontal section aspect ratio of from about 1:1 to about 4:1 and continuously changing vertically into an upper portion having a horizontal section with an aspect ratio of from about 40:1 to about 100:1.

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