Abstract: The use of a coupling agent containing a mercapto, disulfide, tretrasulfide and/or polysulfide end group provides a mercury removal media having increased reactivity, stability, and mercury removal ability. The mercury removal media described herein is prepared by reacting an organophilic clay containing onium ions with a mercapto, disulfide, tetrasulfide, and/or polysulfide end moiety. Alternatively, the clay can be made organophilic by onium ion reaction prior to or simultaneously with the coupling reaction of the mercapto- or sulfide-end group-containing coupling agent.

Abstract: A process for removing selenium from a water stream, in particular a waste water stream, by: 1) the addition thereto of a ferric salt, followed by 2) the addition of a cupric salt and pH adjustment to a pH value in the range of from about 6.5 to about 8.0, thereby forming a copper-and-selenium-containing precipitate, and 3) removing the copper-and-selenium-containing precipitate to thereby form a treated water stream, is disclosed. The optional precipitation and removal of excess copper ions is also disclosed.

Abstract: A process and apparatus for separating suspended solid material from a fluid, comprising the steps of adding in a chamber buoyant media as glass spheres with 30-250 micron diameter (106) to the fluid to form a first mixture of fluid influent and buoyant media, adding a flocculant (108) to the said first mixture to form a second mixture of influent, buoyant media and flocculant, transferring said second mixture to a flotation chamber (200), introducing a pressurised fluid (203) to the second mixture in said flotation chamber, removing separated floating sludge from said flotation chamber, and removing separated clarified effluent from said flotation chamber Optionally, a coagulant may be added after the flocculant.

Abstract: An animal treatment method comprises flushing the animal waste from a barn to a holding tank where the waste is mixed with an alkaline solution to kill pathogens. After neutralization, the solution is separated into solids and liquids. The liquid is treated and recycled as flushing water to clean the barns and/or drinking water for the animals. The solids are separated into digested and undigested feed. The digested feed is further processed for use as a fertilizer and the undigested feed is processed for use as animal feed.

Abstract: The invention relates to a device for purifying water, in particular for the continuous purification of water in the paper industry, said device comprising at least one supply line and at least one drain line for the water. The device also comprises a compression device for at least one sub-stream of the water, an injection device for injecting at least one gas and an expansion device for expanding at least one sub-stream of the water. In addition, the device comprises a unit for separating different phases of the water for purification. The device is characterized by a control system, which detects at least one parameter of the water and controls at least the addition of at least one additive in accordance with the process parameter.

Abstract: Recycled waste water is treated to remove contaminants and produce a sludge cake with a high percentage of solids and to produce a treated recycled waste water that can be discharged into a municipal sewer system.

Abstract: A device for separating metal components from a colloidal suspension or solution uses a vessel for holding the colloidal suspension or solution. A membrane impermeable to the selected metal components of a colloidal suspension or solution is sealed over a support to form a leaf element. The leaf element includes an outlet for the selected components of the colloidal suspension or solution and is extended into the colloidal suspension or solution. The leaf element is controllably vibrated simultaneously with application of a negative or positive pressure which is used to motivate permeation of the membrane by the liquid of the colloidal suspension or solution to purify it. Metals removed by the method include metals with an atomic number greater than 10 including and/or silicon. The colloidal suspension or solution may optionally contain a metal precipitator such as a dithiocarbamate and/or trithiocarbamate to aid in the separation.

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 present invention provides a polyvinylidene fluoride copolymer capable of forming a uniform film, a solution of the copolymer and a thin film comprising the polyvinylidene fluoride copolymer. The polyvinylidene fluoride copolymer of the present invention is characterized in that the ratio of the scattered-light intensity (I) for a 15% solution of the polyvinylidene fluoride copolymer in dimethylformamide solvent to the scattered-light intensity (I0) for dimethylformamide, (I/I0), is 10 or lower. The polyvinylidene fluoride copolymer solution comprises the polyvinylidene fluoride copolymer and an organic solvent capable of dissolving the copolymer.

Abstract: A method of treating animal manure yielding a final liquid fraction and solid fractions whereby the final liquid fraction has a suspended solids (SS) content of about 3 g/L or lower comprising subjecting at least a part of said manure to a first biological passive flotation step in a flotation unit having a hydraulic residency time (HRT) of about 4 to about 24 hours with a polymer to yield a first flotation solid fraction and a first flotation liquid fraction, said method comprising a further treatment.

Abstract: The method is for treating a liquid or slurry with an ultrasonic energy. A movable endless member is provided that is permeable to a liquid. A transverse foil is disposed below the member and extends across the member and a transducer is in operative engagement with the foil. The member is moved about rollers. The transducer generates pressure pulses into the foil to form implosion bubbles in the liquid disposed above the member. The implosion bubbles have a first diameter (d1). A gap is formed between the member and the foil. The gap represents a distance (d2) that is less than the diameter (d1) of the bubbles to prevent any bubbles of critical size to be captured in the gap.

Abstract: The invention relates to a centrifugal separating device and method for clarifying must during wine production, especially with a separator (7). Gas and/or gelatine and/or other additives are added to the must that is clarified in the separating device after the must has passed through the separating device and before it passes through the constant pressure valve (13) of the separating device, as the must is discharged (9), in order to obtain flotation.

Abstract: A method which uses a process reactor having three separate reaction stages to remove high concentrations of heavy metals from acidic wastewater and chemical solutions. During each of three stages the pH level of the wastewater is increased and sludge and flocculate organic and metal hydrocyl matters are removed from the wastewater to provide clean water which is discharged in to a sewer system.

Abstract: An apparatus which uses a process reactor having three separate reaction stages to remove high concentrations of 3000 mg/l heavy metals from acidic wastewater and chemical solutions. During each of three stages the pH level of the wastewater is increased and sludge and flocculate organic and metal hydroxyl matters are removed from the wastewater to provide clean water which is discharged in to a sewer system.

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: 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: A method and apparatus is described for separating contaminants from waste material including waste water derived from a chemical processing or manufacturing plant, such as the waste water from a coconut processing plant. The separation method and apparatus involves the use of a mixer to aerate a partially treated waste water material prior to mixing the aerated material with a new supply of waste water to aerate the waste water feed supply for admission to a separation vessel in which the contaminants of the waste water are collected as sludge at the top of the aerated zone for disposal. The treated waste water now substantially free of contaminants is collected in a clean zone for discharge or recirculation. Prior to discharge the partially treated waste water in the clean zone can be recycled through a recirculation loop containing the mixer. The recirculation loop can be operated independently of the rate of supply of new waste water.

Abstract: An activated sludge process for the clarification of wastewater comprising introducing the wastewater into a reactor where microorganisms consume organic material in the wastewater to form a mixed liquor comprising water, the microorganisms and an activated sludge; separating clarified water from the mixed liquor by filtration through a microfiltration or ultrafiltration membrane; separating the activated sludge from the mixed liquor; adding to the activated sludge at least one high molecular weight water soluble polymer to form a mixture of water and coagulated and flocculated solids; dewatering the coagulated and flocculated solids to form a mixture of dewatered solids and filtrate water; and recycling the filtrate water into the mixed liquor and a method of controlling polymer dosage, preferably using fluorescence emission spectroscopy.

Abstract: Animal waste such as fecal material from swine, chicken, turkey, and cattle is converted into useful forms such as fertilizer, other types of soil builders, and even nutrient feed additives. Devices, systems, and methods are provided that allow economical conversion and in many instances, alleviate the production and release of undesirable gases such as sulfide and ammonia. In one embodiment, undesirable anaerobic and facultative anaerobic bacteria are killed at a greater rate than desirable soil compatible aerobic bacteria. The use of low temperature killing diminishes off gassing commonly associated with other techniques, and the use of gas trapping additives such as zeolites provides enhanced soil building qualities such as slow release of nitrogen and slow release of moisture to soil. The methods allow convenient adjustment of composition, allowing conversion of waste into tailored designer fertilizer suited for particular soils.

Abstract: The coupling of a sewer treatment station to a treatment plant for the flocculation and flotation of water streams and the insertion of said treatment plant for the flocculation and flotation of water streams into a water treatment station. The sewer treatment station is installed upstream from the flocculation and flotation treatment station, in such a way that the outlet of said station is directly connected to the inlet of the flocculation and flotation treatment plant disposed next to the stream bed or next to and interconnected thereto by means of a varying flow canal. The insertion has dynamic introduction of the process of treatment for the flocculation and flotation of fluid beds, all in a closed canal, wherein the flow of secondary streams (E) is dynamically and continuously submitted to flocculation and flotation techniques in an induced flow canal (FE) in the water treatment station.

Abstract: Process for treating liquid manure, comprising the introduction of homogenized liquid manure into a tank, into which are introduced some polymers/copolymers that bring about an interchange to produce the flocculation of colloidal substances and solids in suspension, which are then separated off with the aid of filters. The flocculation is carried out by feeding the liquid manure in at a constant flow rate and introducing the reagent at the same time in the form of a tertiary or quaternary polymer/copolymer, stirring the mixture for a time of between 5 and 15 minutes and then eliminating the suspended solids by flotation, involving the coalescence of the colloidal particles.

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 system for separating particles from a contaminated liquid stream includes an apparatus for mixing the liquid with one or more separation enhancement additives and gases. A pressure reducing device having a flow restrictor element within an enlarged tube receives the mixed liquid and creates bubble laden floccs by reducing the pressure of the liquid stream. The pressure reducing device empties into a bloom chamber of a flotation tank, where the bubble laden floccs are directed upwardly to an upper portion of the flotation tank. The flotation tank is configured such that the bubble laden floccs circulate within the upper portion of the flotation tank until they float to the upper surface, while decontaminated liquid flows to a lower portion of the tank for removal. A skimmer removes the floated contaminated floccs from the upper surface of the flotation tank into a dewatering apparatus.

Abstract: Recycled waste water is treated to remove contaminants and produce a sludge cake with a high percentage of solids and to produce a treated recycled waste water that can be discharged into a municipal sewer system.

Abstract: Raw water is treated with chlorine, chlorine dioxide and ammonia in various stages as it proceeds from raw water acquisition through clarification (e.g., coagulation, flocculation, sedimentation, and filtration) to storage of finished water from which the treated water can be introduced into a distribution system. Chlorine dioxide can be used as a pre-oxidant or disinfectant. Chlorine can be used as a disinfectant or to react with ammonia to produce monochloramine.

Abstract: A process for treating impure cane-derived sugar juice comprises subjecting, in a clarification stage, the juice to microfiltration/ultrafiltration to decrease the levels of suspended solids, organic non-sugar impurities and/or color therein. The resultant clarified sugar juice is sequentially passed through an ion exchange stage by bringing the juice into contact with a strong acid cation ion exchange resin in the hydrogen form, and thereafter into contact with an anion ion exchange resin in the hydroxide form. A purified sugar solution is withdrawn from the ion exchange stage, and concentrated to produce a syrup. The syrup is subjected to primary crystallization in a primary crystallization stage, to produce refined white sugar and primary mother liquor. The primary mother liquor is subjected to secondary crystallization in a secondary crystallization stage, to produce impure crystallized sugar and white strap molasses.

Abstract: The present invention is a floatation process and associated apparatus for removing heavy metal waste from various effluent water streams. The process and apparatus generally introduces a population of fine diameter air bubbles and one or more flocculating chemicals into an effluent stream to produce buoyant floc structures that include the heavy metals and that can be removed from the effluent stream. The present invention provides a reliable, cost-effective means of removing heavy metals from effluent water streams.

Abstract: A method for treating liquid includes directing a pressurized stream of the liquid into a cyclone apparatus having an inlet closed to the atmosphere and a submerged outlet. A liquid vortex is formed along an inner surface of the cyclone apparatus, and a central portion defined by an inner surface of the liquid vortex is substantially evacuated of gases to create a near vacuum condition. Treatment gas may be selectively added to the liquid vortex through the evacuated central portion. Photon energy may be directed through the evacuated central portion and into contact with the treatment gas, or the liquid vortex. Pressure levels within the evacuated central portion are measured using a pressure sensor or gauge. Upon exiting the cyclone apparatus, the liquid is subjected to collision and cavitation forces.

Abstract: This invention refers to the use of surface-active agents as a treatment of effluents containing acetic derivatives by tangential filtration characterized from aqueous solutions containing between 20 and 35% in weight of acetic derivatives having been optionally decanted and filtered in a conventional manner in order to remove suspended impurities, which undergo the addition of one or more surface-active agents, while submitted to the tangential filtration process via polymer membranes, the cutting range of which may vary between 0.001 and 0.

Abstract: The present invention is a floatation process and associated apparatus for removing heavy metal waste from various effluent water streams. The process and apparatus generally introduces a population of fine diameter air bubbles and one or more flocculating chemicals into an effluent stream to produce buoyant floc structures that include the heavy metals and that can be removed from the effluent stream. The present invention provides a reliable, cost-effective means of removing heavy metals from effluent water streams.

Abstract: A water soluble, surface active, polymeric agent is mixed with digestion liquor, preferably with an additional surface active defoamer coagulant agent prior to or during acidification of the alkaline digestive liquor. This results in an easily separable, non-gelatinous, non-gummy, coagulated lignin as a solids, particulate fraction that tends to float on a clarified liquid fraction containing recoverable salts. The solids fraction and the liquid frictions are easily separated, one from the other, by a gravity separation step.

Abstract: Disclosed is a process for reducing the amount of silicon in brine. More specifically the silicon content of the brine is reduced to 1 ppm or less by using low caustic excess. The disclosed process can also be characterized as lowering sodium hydroxide excess (caustic excess) while maintaining the sodium carbonate level thereby obtaining a brine with a low level of silicon. A further purification step employs a sludge blanket.

Abstract: A method of removing synthetic hydrophobic resinous particles from a waste treatment process in which an aqueous cellulosic suspension is formed from waste cellulosic material in a pulping stage, passing the cellulosic suspension to a separation stage in which particles of ink and/or synthetic hydrophobic resinuous materials are separated from the cellulosic suspension, and optionally subjecting the cellulosic suspension to a washing stage and/or thickening stage to provide a treated pulp, in which process water from the separation stage and/or washing and/or thickening stages is clarified in a clarification stage in which suspended solids, comprising synthetic hydrophobic resinous particles are removed, and the clarified water is fed to the pulping stage in a clarification loop and/or combined with the treated pulp, wherein a water soluble cationic polymer is added to the process water at or prior to the clarification stage, characterised in that the water soluble cationic polymer formed from a monomer blend

Abstract: A method for clarifying food processing waste water containing suspended solids comprising (iii) adding to the waste water with an effective amount of at least one vinylamine polymer having a molecular weight of at least 10,000, wherein the polymer is prepared by first polymerizing N-vinylformamide and, optionally, vinyl acetate to form a vinylformamide polymer or a vinylformamide/vinylacetate copolymer and then subjecting the vinyl formamide polymer or vinylformamide/vinylacetate copolymer to acid or base hydrolysis to form a vinylamine/vinylformaide copolymer, a vinylamine homopolymer or a up vinylamine/vinylalcohol copolymer; (ii) coagulating and flocculating the suspended solids; and (iii) separating the coagulated and flocculated suspended solids from the wastewater.

Abstract: The present invention relates to an apparatus and process for separating contaminants from a contaminated fluid, such as wastewater.

Abstract: A novel method that promotes upward mobilization of dense nonaqueous-phase liquid contaminants. In one embodiment, the method comprises the steps of: (1) injecting a treating agent (e.g., a polyaphron solution) comprising a light organic-phase fluid (e.g., kerosene, xylene, octane, hexane, etc.) into the Earth's subsurface, targeted within or adjacent to the dense contaminant source zone; and (2) injecting a post-flush agent comprising a polyvalent cation (e.g., Al3+, Fe3+, etc.), or similar species, once the treating agent is displaced throughout the source zone. The treating agent converts the contaminant to a density less than the density of groundwater by inducing in-situ mixing. The post-flush agent destabilizes the polyaphrons thus allowing the contaminant and the treating agent to mix.

Abstract: Waste water is treated to remove contaminants and produce a sludge cake with a high percentage of solids and a treated waste water that can be discharged into a municipal sewer system.

Abstract: A method is provided for deinking paper. Repulped paper is treated with a deinking agent. The deinking agent comprises a triglyceride. A preferred triglyceride is beef tallow.

Abstract: A method of controlling algae in a municipal water plant including the step of adding an algicide-flocculant solution including 25-50 wt % acidic flocculent, 0-10 wt % polymer flocculant aid, an algicide consisting essentially of copper having a concentration of 0.025-1.275 wt % in the form of a water soluble copper salt, balance water. The algicide-flocculant solution may be added to the water via a clarifier of the water plant, a basin of the water plant, or a mixing chamber. The mixing chamber may be located within the clarifier, adjacent to the basin, or upstream of the clarifier and/or the basin.

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: A method for removing contaminants from a liquid includes filtering objects of a relatively large dimension. The liquid is then mixed with additives to adjust the chemistry of the liquid. The liquid is pressurized and directed through a gasification device to dissolve gas into the liquid. This is accomplished by directing the liquid into an inlet of a hydrocyclone of the gasification device, directing the liquid exiting the hydrocyclone upwards to remove large bubbles, and removing liquid containing dissolved gas from a bottom portion of a vessel of the gasification device. The pressure of the liquid is then reduced and the liquid is introduced into a separation tank, and the contaminants are removed from the liquid by stratification. The treated water is removed from the separation tank, and sludge formed by skimming flocs from a liquid surface of the tank is subjected to a dewatering process.

Abstract: A process for treating sludge is disclosed. Sludge to which a flocculating agent has been added is stirred by a stirring pump or shear-stirred by a liquid shear-stirrer prior to initiation of flocculation reaction of the flocculating agent to render the flocculating agent in a fine particulate state to thereby disperse, diffuse or distribute the flocculating agent in a fine particulate state throughout the sludge, so that flocks or aggregate structure type flocks or blocks can be efficiently formed. A treating line is constructed such that the sludge can flow therein as a laminar flow. The distance from a flocculating agent injection part to a stirring pump is made to a distance such that the flocculating agent can pass through in a reaction initiation time obtained in advance for the flocculating agent.

Abstract: A calcium carbonate mineral is placed in a lower portion of a second water tank, while sludge precipitated in a sixth water tank is returned to an upper portion. A blower and an air diffusion pipe weakly aerate the lower portion. Thus, an unreacted chemical sludge zone is formed in the upper portion of the second water tank. As a result, the second water tank can execute a primary treatment of fluorine in a waste water by the calcium carbonate mineral, a secondary treatment of fluorine and a primary treatment of phosphor by unreacted chemicals, treatment of surface active agent by microorganisms in a return sludge and reduction treatment of hydrogen peroxide by anaerobic microorganisms in the return sludge. The unreacted chemicals are thus reused, so that the amount of generation of waste can be reduced and concurrently the treatment can be executed with energy conservation.

Abstract: An algicide-flocculant solution for use in treating raw water in a municipal water plant to control algae, the algicide-flocculant solution including 25-50 wt % of an acidic flocculant, 0-10 wt % of a polymer flocculant aid, an algicide of essentially copper having a concentration of 0.025-1.25 wt % in the form of a water soluble capper salt, and balance water. Uniform mixing of the flocculant into the raw water simultaneously uniformly mixes the algicide of the algicide-flocculant solution into the raw water. The acidic flocculant is preferably aluminium sulfate, iron sulfate, iron chloride or mixtures thereof. The water soluble copper salt is preferably copper sulfate, copper chloride, copper nitrate, copper acetate or mixtures thereof. Moreover, the flocculant aid is a high molecular weight quaternary amine such as diallyldimethylammonium chloride.

Abstract: An apparatus and method for separating microalgae from water without rupturing cells. The method comprises the steps of flocculation, flotation and dehydration. Microalgae suspension from a reservoir is passed to a mixer unit where flocculation is carried out, using modified starch or other flocculating agents. The suspension is then directed to a flotation column. Dissolved gas in water is transferred to the flotation column through a disperser. A layer of foam containing microalgae is formed on the liquid layer in the column, which can be skimmed off through an overflow outlet. The flotation column is a telescopic column of adjustable height, which enables the position of the overflow outlet to be aligned with the level of the foam layer for efficient foam removal. Foam containing microalgae is then passed to a filtration unit for cloth filtration, followed by drying in a drying chamber.

Abstract: This invention is directed to a cationic terpolymer comprising (a) a first monomer unit selected from acrylamide and methacrylamide; (b) a second monomer unit selected from dimethylaminoethyl acrylate methyl chloride quaternary salt, 3-(acrylamido)propyltrimethylammonium chloride, 3-(methacrylamido)propyltrimethylammonium chloride, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate dimethylsulfate quaternary salt, dimethylaminoethyl methacrylate dimethylsulfate quaternary salt, diethylaminoethyl acrylate methyl chloride quaternary salt and diethylaminoethyl acrylate dimethylsulfate quaternary salt; and (c) a third monomer unit selected from benzyl methacrylate, 2,2,2-trifluoroethyl acrylate, acrylamide diacetone, N-phenylacrylamide, 2,2,3,3-tetrafluoropropyl acrylate and poly(propylene glycol)methacrylate. The terpolymer is useful for dewatering a variety of sludges.

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: A variety of methods to prepare a polymer composition containing at least one polymer and at least one modified pigment are described. The methods, in part, involve introducing a slurry containing at least one modified pigment into an emulsion or solution polymer prior to dewatering. Other polymer systems can be used including aqueous based polymerizations and solvent-based polymerizations, which can include free radical polymerizations. Other methods involve the formation of a modified pigment in the presence of an emulsion or solution polymer and then recovering the polymer composition containing the modified pigment. Compositions containing at least one modified pigment and the emulsion or solution polymer are also described as well as uses for the polymer compositions of the present invention.

Abstract: A process for treating waste water containing a resin is disclosed, which includes the steps of adding a polyamine compound to waste water containing at least a resin to coagulate at least water-insoluble matter in the water to form coagulated particles, adding a polyacrylamide polymer to cause those particles to grow into flocculated flocs, and separating the flocculated flocs. The process of the invention can treat waste water containing a resin in an industrially beneficial way without producing a large amount of sludge is disclosed.

Abstract: A process for treating waste water containing cutting oil is disclosed, which includes the steps of adding a cationic organic compound to waste water containing used cutting oil to coagulate water-insoluble matter in the water and to thereby form coagulated particles, adding an anionic organic polymer to cause those particles to grow into flocculated flocs, and separating the flocculated flocs. The process of the invention can treat waste water containing used cutting oil in an industrially beneficial way without producing a large amount of sludge.