Abstract: The invention relates to a process for purifying a crude 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate containing an impurity. The process includes bringing the crude 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate into contact with a poor solvent in which 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate is substantially insoluble, thereby removing the impurity from the crude 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate. Alternatively, the process includes precipitating crystals of 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate from a solution of the crude 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate. Thus, it is possible to produce 1,1,1,5,5,5-hexafluoroacetylacetone dihydrate of high purity. This product makes it easy to produce 1,1,1,5,5,5-hexafluoroacetylacetone of high purity.

Abstract: A cyclic olefin polymer having a small content of a catalyst residue, a production process for the same and use of the same as an optical material. Catalysts used for polymerization and/or hydrogenation reaction for forming the cyclic olefin polymer are decomposed efficiently by adding at least one compound selected from the group consisting of an &agr;-oxyacid and &bgr;-oxyacid having one hydroxyl group and one carboxyl group in the molecule and derivatives obtained by substituting hydroxyl group thereof by an alkoxyl group, and the decomposition products are removed by rendering them insoluble in a reaction solvent used for the polymerization and/or hydrogenation reaction and precipitating them efficiently.

Abstract: A method of treating an aqueous stream having inorganic material dissolved therein, the method comprising the steps of: (a) adding organic solvent to the aqueous stream in an amount effective to form an inorganic precipitate comprising at least a portion of the inorganic material; (b) removing at least most of the organic solvent from the aqueous stream by vacuum membrane distillation; and (c) after step (b), removing at least most of the inorganic precipitate from the aqueous stream.

Abstract: The present invention comprises a method for reducing the viscosity of the settled mud or underflow of a raked thickener thereby reducing the torque necessary to move the rake blade through the settled mud. The method includes the step of delivering a viscosity modifier to the settled mud and in front of the rake blade by pumping the viscosity modifier down the rake arm to an area in front of the rake blade. The method also includes an improved rake mechanism that includes a means for delivering viscosity modifier to the settled mud and in front of the rake blade. The present invention also includes a method for increasing the rate of consolidation of flocculated solids in a slurry.

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 method and system for removing heavy metals from wastewaters is provided wherein the wastewaters are pre-treated with a polymeric metal removing agent to assist in the removal of the heavy metals. The polymeric metal removing agent promotes the precipitation of large particles which may then be filtered by a high flow rate, low pressure filtration system.

Abstract: An apparatus and method for removing a metal residue from a process waste stream. In one aspect, an apparatus for a waste stream treatment assembly is provided which includes a waste stream metal removal reactor having at least one inlet and at least one outlet, a fluid delivery system connected to the at least one inlet of the waste stream metal removal reactor and a chelating agent supply source, and a filtering member disposed in communication with the at least one outlet of the waste stream metal removal reactor. In another aspect, a method is provided which includes adding a chelating agent to a process waste stream to form a metal complex, and removing the metal complex from the process waste stream prior to disposal.

Abstract: A method for removing a contaminant from water includes mixing droplets of a substantially non-water soluble oil with water to combine with the contaminant. The oil can include polar or ionic functional groups. A chemical destabilizer is added to the water to coagulate and aggregate the oil-contaminant mixture. The mixture is then separated from the water by gravity settling, filtration, or dissolved air flotation, thereby removing the contaminant.

Abstract: An improved process for the treatment of water, selected from livestock wastewater and a livestock water stream, which process comprises adding to said water a composition comprising a sufficient amount of an acid to lower the water pH to less than 3.5 to 2.0; and wherein said acid is selected from the group of 1,3,5-Triazine-2,4,6-(1H,3H,5H)-hydroxyalkyltriglyoxilic acid (PR-1409SA); 2,2-oxy-diacetic acid; 2,2-ether diglycolic acid; sulfamic acid; and sulfuric acid.

Abstract: The present invention comprises a method for reducing the viscosity of the settled mud or underflow of a raked thickener thereby reducing the torque necessary to move the rake blade through the settled mud. The method includes the step of delivering a viscosity modifier to the settled mud and in front of the rake blade by pumping the viscosity modifier down the rake arm to an area in front of the rake blade. The method also includes an improved rake mechanism that includes a means for delivering viscosity modifier to the settled mud and in front of the rake blade. The present invention also includes a method for increasing the rate of consolidation of flocculated solids in a slurry.

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: A method has been discovered for removing organics, such as water soluble organics (WSO), from fluids containing water, such as oil process water, by contacting the fluid with an effective amount of an organic ammonium salt. No added acid is necessary, although in some embodiments, weak acids such as glycolic acid, can be used to give synergistic improvement in organic removal. Suitable organic ammonium salts have the formula:R.sup.1 R.sup.2 R.sup.3 N.sup.+ H X.sup.-where R.sup.1 is a saturated or unsaturated alkyl group or an aryl group, or saturated or unsaturated alkyl group or an aryl group substituted with a heteroatom selected from the group consisting of N, O, S, P and halogen; R.sup.2, and R.sup.3 are independently H or a saturated or unsaturated alkyl group or an aryl group, or saturated or unsaturated alkyl group or an aryl group substituted with a heteroatom selected from the group consisting of N, O, S, P and halogen; and X is a halogen atom or an anion of a protic acid.

Abstract: A system and method for the detection and removal of copper from wastewater streams from semiconductor or printed circuit board manufacturing is described and claimed. The detection system and method involve the addition of a reagent that reacts with copper to quench the fluorophore present, with the decrease in fluorescence being detected by a fluorometer. The reduction of fluorescence is then used to calculate the amount of copper present in the form of Cu+2 ion in the wastewater. The removal system and method involve either the addition of a polymer that reacts with copper to form an insoluble precipitate with said precipitate then being removed by using any technique commonly known in the art; or the use of an ion exchange column to remove the copper from the wastewater stream.

Abstract: The present invention relates to methods for concentrating bacteria from a viscous biological sample. The methods involve adding to the sample a water-soluble, density-lowering agent having a density of 0.7 to 0.9 g/ml and a boiling point greater than 50.degree. C. The invention also relates to methods for concentrating bacteria and free bacterial nucleic acids from a biological sample that involve mixing with the sample a density-lowering agent and a monovalent salt.

Abstract: A sludge, preferably derived at least in part from a paper mill, pulp mill or deinking plant, and which contains at least secondary sludge or primary sludge comprising deinking waste, recycled paper waste or mechanical pulping waste, is flocculated by being mixed with a phenolic material and a polyalkylene oxide and is then subjected to dewatering.

Abstract: The present invention relates to dewatering of an aqueous slurry of calcium carbonate. More particularly, the present invention relates to the use of non-ionic surfactants in dewatering aqueous slurries of an aragonitic precipitated calcium carbonate. Calcium carbonate slurries dewatered using the non-ionic surfactants of the present invention have higher weight percent solids, decreased dispersant demand, and result in higher productivity.

Abstract: Polyether polyols are produced by acid-catalyzed polyaddition of alkylene oxides to starter compounds having active hydrogen atoms. Perfluoroalkylsulfonic acid salts of metals from Group IIIA of the Periodic Table of Elements (corresponding to the IUPAC Convention of 1970) are used as the catalyst. The polyaddition reaction is carried out at a temperature of from 40 to 200.degree. C. at normal pressure or pressures from 0 to 20 mbar (absolute). An inert organic solvent may optionally be included in the reaction mixture. Substantially all of the catalyst is removed from the polyether polyol-containing reaction mixture by lowering the temperature and/or by addition of a precipitating agent and/or by extraction with water. If desired, the recovered catalyst may be used in subsequent polyaddition reactions.

Abstract: A process is disclosed for flocculating particles in a liquid suspension by mixing the suspension with a pyrrolidone having alkyl, alkenyl, aryl, alkylaryl, and arylalkyl radicals from 1 to 18 carbon atoms to form a mixture at a temperature above a minimum flocculation temperature for the mixture.

Abstract: A method and treatment composition for neutralizing formaldehdye. The treatment composition contains polyethylenimine, urea and an acid having a pH of less than 6. Treatment of formaldehyde solutions with the treatment composition results in a suspension that it easily disposable and non-toxic.

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: Method of purification by extraction of at least one substance to be isolated from a liquid medium, comprising an addition to the latter of an organic compound, entrainable by a vapor, which has a molecule with an acidic-basic character in the Lewis sense due to at least one atom of N, O and/or S forming one or more active sites provided with a free electron pair, this pair or these pairs being in resonance with at least one other pair carried by the molecule, this addition being carried out in a quantity sufficient to give rise to a product of an equilibrium reaction between the organic compound and the said at least one substance to be isolated, and sufficient to cause a precipitation of this equilibrium reaction product, a filtration of the precipitate and an entrainment by vapor of the organic compound from the precipitate, with a yield of the substance to be isolated in purified form.

Abstract: This invention relates to a process for the purification of polyether polyols. This process enables the removal of residual alkaline metal catalyst from produced polyether polyol. It comprises a) adding glycerine to a polyether polyol that contains Group IA alkaline metal catalyst to form a precipitate, and b) separating the precipitate formed in a) to provide a purified polyether polyol. The present invention also relates to the purified polyether polyol produced by this process, the precipitate produced by this process, and the use of the precipitate as an alkaline metal catalyst in a process for the production of polyether polyols.

Abstract: The present invention describes a process and an apparatus for treating sludge having both liquid and solid constituents. The sludge is first heated to a minimum optimum draining temperature. During heating, mechanical dewatering of the sludge occurs. In a preferred embodiment, a process is disclosed for treating waste paint sludge generated from a paint spraybooth, and heating is performed using microwave radiation. Liquid released from the paint sludge during dewatering can be recycled back to the spraybooth water, and vaporized exhaust generated during heating can either be condensed into liquid form and recycled, or incinerated and, preferably, sparged through untreated sludge to pre-heat it.

Abstract: A method of separating heteropoly compounds from mixtures of polyethers, polyesters and/or polyether esters, a protic component and heteropoly compounds, wherein the protic component is removed from the mixture and subsequently separating off the heteropoly compound as a separate phase. The polymer phase which remains is preferably brought into further contact with a solid adsorbent that is capable of adsorbing heteropoly compounds.

Abstract: The invention involves the demulsification and liquefaction of hydrocarbon based sludges. A demulsifier and a liquefaction agent and methods of using the same are disclosed. In a preferred embodiment, the demulsifier contains a salt of DDBSA, polypropylene glycol, and citrene. In a preferred embodiment, the liquefaction agent contains a glycol ether and sodium silicate. In another preferred embodiment, the liquefaction agent contains a glycol ether and citrene. In preferred practice, the sludge is treated with the liquefaction agent, circulated, treated with the demulsifier, and circulated further. An object of the invention is to provide a hydrocarbon based sludge that is sufficiently liquefied to be pumped and which is sufficiently demulsified to allow the waters, oils, and solids in the sludge to separate.

Abstract: Disclosed is an oil separating method in which oil-contaminated water in a separation tank is mixed with air bubbles in a bubble-generating apparatus provided at the bottom of the separation tank to jet out said air-water mixture into the separation tank,wherein a surfactant and/or an antifoamer are(is) previously added to the oil-contaminated water.

Abstract: Methods of removing contaminant metals from aqueous waste streams. A preferred method includes providing an aqueous waste stream containing a metal having a valence of at least one, such as zinc, lead, chromium, copper, iron, aluminum, manganese, cadmium, gold, silver, and mixtures of these metals. The waste stream is substantially free of calcium and magnesium. The process also includes forming a substantially insoluble precipitate of said metal by mixing with the waste stream fatty acids; zinc, potassium, and sodium salts of fatty acids; and mixtures of these materials. The metal precipitate is separated from the waste stream and the water that is subject to the removal process remains substantially free of calcium and magnesium throughout the entire process. The methods of the present invention are particularly effective for the removal of trace amounts of zinc from aqueous waste streams from polystyrene processes.

Abstract: A treated solvent composition for washing mechanical parts or the like. The solvent contains not more than about 25% aromatic solvents with the balance being aliphatic and other non-aromatic solvents having a flashpoint of at least 100.degree. F. The solvent is treated with up to 10 parts of an additive composition selected from the group consisting of C.sub.14 and lower alcohols, diols, polyols, lower glycols, and lower glycol ethers and mixtures thereof. In use, finely dispersed contaminant particles settle from the body of the solvent more rapidly than in untreated solvent and the resulting clarified appearance enables the solvent to be used longer and more effectively in a cleaning operation.

Abstract: This invention relates to the preparation, composition and applications of suspensions of ultra-small, substantially non-aggregated, non-crystalline particles of predetermined uniform size which, when suspended in a liquid, contain entrapped gaseous bubbles. These gaseous bubble particles are prepared by simultaneous co-precipitation of two compounds. In accordance with the present invention, the two compounds chosen for co-precipitation are such that one is substantially more soluble than the other in a given vehicle. When this vehicle is used for washing the co-precipitated particles, part of the soluble material is dissolved leaving a porous matrix. The porous particles then are dried and stored. The porous particles, which can be resuspended immediately prior to use, contain entrapped gas in the evacuated crevices or pores which is not displaced for a period of time because of surface tension of the suspending vehicle.

Abstract: Water is separated from crude oil by a process in which the oil demulsifier used is a mixture ofA) compounds which have demulsifying activity and are of the structure type of the(a) polyethyleneimine alkoxylate,(b) mono- or oligoamine alkoxylate,(c) alkoxylated alkylphenol/formaldehyde resins,(d) alkoxylated amine-modified alkylphenol/formaldehyde resins,(e) co- or terpolymers of alkoxylated acrylates or methacrylates with vinyl compounds,(f) condensates of mono- or oligoamine alkoxylates, dicarboxylic acids and alkylene oxide block copolymers, where these condensates may furthermore be completely or partially quaternized at the nitrogen atoms, or(g) compounds (a) to (f) reacted with crosslinking agents andB) as a demulsifying assistant, a polyalkylene glycol ether which has no demulsifying activity and is of the general formula I or IIR.sup.1 ?(OA.sup.1).sub.a --OH!.sub.n (I)H--(OA.sup.1).sub.b --(OA.sup.2).sub.c --(OA.sup.3).sub.d --OH(II)whereR.sup.1 is a monovalent to decavalent C.sub.1 -C.sub.

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.

Abstract: This invention relates to the preparation, composition and applications of suspensions of ultra-small, substantially non-aggregated, non-crystalline particles of predetermined uniform size which, when suspended in a liquid, contain entrapped gaseous bubbles. These gaseous bubble particles are prepared by simultaneous co-precipitation of two compounds. In accordance with the present invention, the two compounds chosen for co-precipitation are such that one is substantially more soluble than the other in a given vehicle. When this vehicle is used for washing the co-precipitated particles, part of the soluble material is dissolved leaving a porous matrix. The porous particles then are dried and stored. The porous particles, which can be resuspended immediately prior to use, contain entrapped gas in the evacuated crevices or pores which is not displaced for a period of time because of surface tension of the suspending vehicle.

Abstract: Disclosed is a process to remove tumour necrosis factor .alpha. (TNF.alpha.) or/and bacterial lipopolysaccharides (LPS) from an aqueous liquid, in particular blood, blood plasma or serum, in an extracorporeal perfusion system after removing corpuscular blood components if necessary, wherein(a) the pH value of the body fluid is adjusted to pH<6,(b) a precipitation reagent in the form of a polyanion is added,(c) precipitated substances are removed by filtration or/and centrifugation and(d) the resulting liquid is passed over an anion exchanger.

Abstract: Small, wet particulate material is effectively dried by adding a hydrophobizing agent to coat the surfaces of the particulates, and then mechanically removing water droplets from the surfaces of the particulates. Once on the surface of the particulates, the hydrophobizing reagent makes the particulates relatively more hydrophobic and increases the water contact angle on the particulates. The moisture content of the particulate material can easily be reduced to levels below 20%, below 10%, and even below 5%. The process can be used to dewater a wide variety of constituents including coal particles, clays, sulfides, phosphorous compounds, minerals, metals, waste sludge, etc. Particularly preferred hydrophobizing reagents include mono unsaturated fatty esters and polysiloxane polymers.

Abstract: A method of separating oleophilic-hydrophobic material from wash water is disclosed. The method comprises the steps of mixing with the wash water, either alone or in combination, about 30-2100 ppm of a surfactant having the formula: ##STR1## where n is 6-20; and about 1-200 ppm of an enzyme selected from the group consisting of proteases, amylases, lipases, cellulases, pectinases and mixtures thereof. The mixture of wash water surfactant and/or enzyme is then permitted to stand for a time sufficient for the oleophilic-hydrophobic material to separate.

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

Abstract: Red blood cells are removed from whole blood or a fraction thereof by contacting whole blood with a combination of an agglutinating agent and nucleating particles to form clusters of red blood cells. High molecular weight polyethylene glycol may be added further to enhance agglutination. The clusters of red blood cells are much larger than the size of individual red blood cells, so that the clusters can easily be filtered through a porous medium. The plasma which is substantially free of red blood cells is further passed through a filter that optionally contains an additional agglutinating agent.

Abstract: A method for removing aluminum from blood includes the step of adding to the blood an anticoagulant and a complexing agent for aluminum or one compound effective in both preventing coagulation of blood and capable of complexing aluminum. The complexing agent or compound capable of complexing aluminum is allowed to intermingle with the blood and complex with aluminum present in the blood. The complex of complexing agent and aluminum formed during the intermingle step is then separated using a semi-permeable membrane, and the blood is recovered. The method is particularly useful in treating patient's having aluminum intoxication.

Abstract: In a process for dehydration and concentration of sewage sludge containing activated sludge with the aid of organic and/or inorganic flocculators, the activated sludge content is produced in an aerated biological purification stage in presence of a composition containinga) folic acid and/or dihydrofolic acid or at least one ammonium, alkali metal, alkaline earth metal and/or alkanolammonium salt thereof andb) a water-soluble molybdenum compound,whereby an improved sludge dehydration of the activated sludge content is achieved.

Abstract: The present invention is directed to the use of water-soluble compositions containing a compound having a Lewis base group attached to a hydrophobic group where the Lewis base group is capable of donating at least one lone pair of electrons to a metal. These compositions are effective in treating acid mine drainage by treating the source of the acid mine drainage as well as the acid mine drainage waters. These compositions are also effective in removing metal and non-metal ions from aqueous sources and the process can be modified to allow the selective removal of metal and non-metal ions from aqueous sources.

Abstract: A powdered composition for treating spent dry film stripping and/or developing solutions comprising: 10 to 70 percent by weight of an aluminum source, such as aluminum sulfate, aluminum chloride; and 28 to 90 percent by weight of siliceous particulates, such as diatomaceous earth, sodium potassium aluminum silicate or expanded perlite. The powdered composition may also include 3 to 35 percent by weight of a metal precipitation agent, such as trimercapto-s-triazine, sodium dimethyldithiocarbamate, starch xanthate, sodium diethydithiocarbamate and thio red, to precipitate the metal from the spent solutions and/or 0 to 10 percent by weight of a dust-suppression agent such as water or propylene glycol. A method of using the disclosed compositions is also revealed in this application.

Abstract: An ion exchange process utilizes a chemical system in which sodium nitrate is reacted with an acidic solution of urea to selectively precipitate nitrate ions from waste brine in the presence of chloride ions, thereby allowing for the recycling of the brine regenerant.

Abstract: A method for the prevention of fouling in a distillation train of a hydrocarbon processing unit. The method involves the precipitation of foulants contained in the hydrocarbon fluid prior to distillation. Precipitation of fouling components occurs when the liquid to be distilled is contacted with a high boiling fluid which is a non-solvent for the foulant causing species but is a solvent for the liquid that is to be distilled.

Abstract: A process for the precipitation and separation of inorganic species form aqueous solutions. The method comprises the step of adding a miscible organic solvent to inorganic-aqueous solution so that a solid precipitate from the aqueous solution is formed. The resultant solid precipitate is separated from the organic-water mixture. After separating the solid precipitate, the miscible organic solvent is removed and recovered from the organic-water mixture by applying vacuum or other means of recovery. The separated miscible organic solvent can then be condensed and returned to the process. The water is stripped of traces of miscible organic solvent and removed from the system as product water.

Abstract: Fine particles are dewatered in an energy efficient process in which a non-polar liquid or a mixture of different hydrophobic liquids are used to displace the water from the particle surface. Thermodynamically, this process is spontaneous. The only energy required for this process is to recover the hydrophobic liquid(s) for recycling purposes. The hydrophobic liquids are recovered in gaseous form either by lowering the pressure or by heating, and converted back to liquid form for re-use. The most economical reagents that can be used for this purpose include propane, butane, pentane, and ethane. Carbon dioxide may also be used for the dewatering process described in the present invention. The process of dewatering by displacement is capable of achieving the same or better level of moisture reduction as thermal drying but at substantially lower energy costs.

Abstract: A method of removing silver from a solution containing silver halide and silver ion is described, which comprises a step of adding an a sulfur atom-containing hydrophilic polymer chelating agent to the solution.

Abstract: A novel process and related apparatus for removing common contaminants from used motor oil. Propane, butane or similar solvent is mixed with the contaminated oil to form a solution. This solution is agitated and then given time to settle thus allowing gravitational separation of asphaltic pollutants. The solution is then percolated through a columned filter to remove heavy metallic contaminants and the solvent recovered by heating the solution.

Abstract: A process and apparatus for the treatment and recovery of spent vehicle coolant that involves the following steps:a) removing the spent coolant from the engine;b) treating the spent coolant with sodium dimethyldithiocarbamate to cause dissolved metals therein to form insoluble particles;c) treating the spent coolant of step b) with an aqueous basic coagulating agent such as a polyquaternary ammonium compound in its hydroxide form;d) filtering the spent coolant from step c) through a set of filters and then through a bed of carbon particles, to produce a relatively cleaner liquid; ande) adding to the relatively clear liquid a combination of corrosion inhibitors, buffering agents and alkali, whereby the treated coolant can be recycled to the vehicle for effective coolant performance therein.

Abstract: Finely divided solids suspensions can be dewatered by adding to the solids suspension a mixed hydroxy ether of the formula ##STR1## wherein R.sup.1 is a linear hydroxy alkyl group containing from 2 to 16 carbon atoms with the hydroxyl group on the carbon atom adjacent to the carbon atom with the ether linkage and R.sup.2 is a linear alkyl group with 1 to 15 carbon atoms with the proviso that the sum of the total carbon atoms in R.sup.1 and R.sup.2 is 5 to 17, R.sup.3 is a linear or branched alkyl group with 1 to 12 carbon atoms and n is a number of from 1 to 20. The mixed hydroxy ethers are readily biodegradable, generate very little foam and have a low solidification point.

Abstract: A method for preventing activated sludge from losing its settling ability, which sometimes happens in solid/liquid separation in an activated sludge treatment of an aqueous organic waste and causes the so-called bulking and scumming of the sludge. This method involves adding either (a) a nonionic and/or an anionic surfactant, (b) a combination of a nonionic surfactant with a cationic surfactant of a form of quaternary ammonium salt or (c) a combination of a nonionic surfactant and a cationic surfactant of a form of a quaternary ammonium salt with a cationic organic flocculant, to the activated sludge treatment system.