Abstract: The process relates to the treatment of aqueous solutions of polyhydric alcohols to remove heavy metal components, oils, organic contaminants and, optionally, water. The process is particularly well suited for use in the treatment of spent antifreeze/coolant from the cooling systems of internal combustion engines.

Abstract: Selenium compounds present in aqueous liquids can be removed using a poly dithiocarbamate materials. The selenium compounds are then removed by precipitation or sedimentation. Optionally, an oxidizing agent may be added to the system prior to the addition of the poly dithiocarbamate. Various filtration methods may be employed to remove the selenium-dithiocarbamate materials from aqueous liquids.

Abstract: Metals contained in various wastewaters are selectively recovered as metal precipitates and/or as spinel ferrite and water suitable for discharge into the environment is obtained. High grade magnetic spinel ferrite is recovered from wastewaters having aluminum and arsenic if present in the wastewater, removed from the wastewater. There are three process stages for the treatment of wastewater. In the first process stage which is optional, at least a portion of at least one non-ferrous or non-ferric metal is precipitated from the wastewater by subjecting the wastewater to an oxidizing agent to increase the oxidation-reduction potential of the water, by adjusting the pH of the wastewater to a pH at which the metal precipitates from the water and by adding an organic or inorganic sulfur compound, capable of causing the metal to form a precipitate, to the water in a quantity sufficient to precipitate the metal.

Abstract: A process for inhibiting the formation of an unwanted precipitate comprising [H.sub.2-n TMT]Na.sub.n [HNR.sub.3 ] during the precipitation of silver mercapto-s-triazine (AgTMT) from a silver containing photoprocessing solution, comprising the steps of:(a) providing a base solution;(b) providing a reagent solution containing mercapto-s-triazine (TMT), or a water soluble salt thereof;(c) mixing the TMT reagent solution with the photoprocessing solution; and(d) adding sufficent base to increase the pH of the mixture of the TMT reagent and photoprocessing solutions above the pH of the mixture before addition of base, and the base is mixed:(i) directly to the photoprocessing solution before mixing TMT reagent with the photoprocessing solution; or(ii) with the photoprocessing solution concurrently with TMT reagent; or(iii) immediately after the point TMT reagent begins mixing with the photoprocessing solution.

Abstract: Additives are usually diluted before they are added to a geothermal brine processing stream. It has been found that one preferred diluent is the conditioned steam condensate produced after power generation in the geothermal plants. One class of additives beneficially diluted by the conditioned steam condensate are crystal structure modifiers. When it is diluted with the steam condensate, the heat-sensitive crystal structure modifier is prevented from being degraded by the heat of the brine so that when blended with the geothermal brine the crystal structure modifier can perform its function of inhibiting the precipitation of alkaline earth salts.

Abstract: A process for removing silica in dissolved or colloidal form from an aqueous liquor comprising, precipitating/adsorbing the silica with or onto a precipitant/adsorbent, typically a compound containing aluminium, magnesium, or iron, forming floccs of the precipitated/adsorbed silica, and separating the floccs from the liquor.

Abstract: A process for separating the components of an emulsion. The process comprises, adjusting the pH of the emulsion to 4 less, adding a coagulant to the emulsion, forming a substantially uniform dispersion of inert particulate carrier in the emulsion adding a polyelectrolyte flocculent either during or after the step of forming the substantially uniform dispersion of inert particulate carrier in the emulsion to form floccs of the inert particulate carrier, the dispersed liquid phase, and the contaminants, allowing the floccs to settle, and separating the relatively clarified continuous liquid phase from the settled floccs.

Abstract: The invention provides a method for dewatering coal tailing aqueous slurries. The method including the step of adding to the slurry a flocculant composition including a vinylamine polymer including from about 1 to about 100 mole percent vinylamine and from about 1 to about 99 mole percent of at least one monomer selected from the group consisting of vinylformamide, vinyl acetate, vinyl pyrrolidinone, vinyl alcohol and the esters, amides and salts of acrylic acid and methacrylic acid.

Abstract: The invention discloses a method for treating a heavy metal containing waste water by using acorns. Acorns and nuts of other trees belonging to the Eagaceae group are dried at the room temperature and under the sun beams. Then acornic acid is extracted from the dried acorns. Then the acornic acid is filtered until it becomes colorless. A heavy metal containing waste water (low concentration and high concentration) is maintained at pH=8-11.5 by adding NH.sub.4 OH, Ca(OH).sub.2 and NAOH. Then the acornic acid is added into the waste water, and then, Ca.sup.++ ions singly or together with other divalent cations are added by 50 ppm. Then this solution is agitated for several minutes, and then, the heavy metals are precipitated, or the solution is filtered, thereby treating the heavy metal containing waste water.

Abstract: The present invention provides for a novel method of removing emulsified oils, dissolved solids and particulates from a water containing liquid wastestream comprising chemically treating the wastestream with an acid, a coagulant, and a flocculant and subsequently flowing such treated wastestream upwardly through a vertical plate pack chamber.

Abstract: A precipitating agent containing thioacetamide is described for the precipitating of heavy metals from flue gases and waste waters, it containing thioacetamide (C.sub.2 H.sub.5 SN) in a 1-20% aqueous solution, which, in addition, contains a buffer substance in order to prevent hydrolyric spontaneous decomposition, the solution having a pH of between 5.5 and 9.0.

Abstract: A process for removing proteinaceous materials, fats and oils from food processing wastewater using a coagulant such as lignin or a halogen ion containing compound together with a flocculant such as a natural polymer such as a polysaccharide or synthetic polymer is described. The combination of lignin or halogen and polymer is effective for coagulating and flocculating proteinaceous materials, fats and oils in food processing wastewater at low pH.

Abstract: An improved process is provided for the steam conversion of dilute printer ink washup fluids, and especially those of a single color, in order to permit reuse of the ink fraction of the fluids as reconstituted printing inks. Preferably, the washup fluids are acidified to create a pin floc therein, with a final pH of from about 2-7; the acidified fluid is then contacted with a stream of steam in a hydroheater (16) in order to convert the residual ink fraction and permit reconstitution thereof into printing ink. The acidifying agent is preferably an acid polymer or an inorganic acid such as HCl or H.sub.2 SO.sub.4.

Abstract: A wastewater treatment system and method for chemical precipitation and removal of metals from wastewater in a continuous or batch treatment process includes an ion-selective sulfide electrode and a reference electrode disposed in a precipitation tank for measuring an electrochemical potential therebetween in a predetermined range. A controller unit is provided which is responsive to the electrochemical potential in the predetermined range and is connected to a precipitant feed unit for automatically controlling the chemical precipitant fed into the precipitation tank.

Abstract: The invention pertains to the purification of commercial, industrial and institutional waste streams in order to bring them into dischargeable compliance with environmental standards. The invention provides a system for removing contaminants, such as fats, oils and grease (FOGs) and total petroleum hydrocarbons (TPHs), from waste effluents on an essentially continuous basis. During the treatment process, the FOGs and TPHs disposed within the textiles to be cleaned are treated with an alkaline, pH- or acid-sensitive detergent, causing their emulsification. The effluent waste stream is then treated by removing the solids and particulates. The alkaline emulsion is broken up by acidification of the wastewater, thereby releasing and dispersing the FOGs and TPHs. The FOGs and TPHs in the broken-up and dissolved emulsion are agglomerated by the introduction of an organic, cationic polymer.

Abstract: A method for removing metal compounds from waste water comprising the steps of adjusting the pH of the water to from 5 to 12 and preferably 6 to 9; aerating the waste water; adding a flocculating agent to the water and allowing floccules including metal compounds to form; and separating said floccules including metal compounds from the water. An apparatus for carrying out this method is also disclosed.

Abstract: Oil well production fluid composed of oil and water and containing in excess of 100 ppm water soluble petroleum carboxylates in anionic form dissolved in the water is treated by acidifying the fluid to a pH of 6.0 or lower with a combination of a strong organic acid and a strong mineral acid and then is intimately mixed. The oil and water are separated one from the other. The content of the water soluble organics in the water is thereby substantially transferred to the oil phase. In a second aspect of the invention, water used to extract corrosive compounds to render the oil suitable for fueling gas turbine power plants is acidified to a pH of 6.0 or lower and is thereafter intimately mixed with fuel oil.

Abstract: A highly colored dye wastewater is treated by a sequence of steps to obtain a color reduction of 90 percent or more. The method requires acidifying the wastewater and adding a cationic flocculant. A reducing agent is then, optionally, added to further reduce the color value of the wastewater and produce an oxidation-reduction potential of at least -200 and, generally, about -400 to -800. The reducing agent is, preferably, either a hydrosulfite or both a bisulfite and an alkali metal borohydride.

Abstract: A treatment method for removing arsenic from water includes conditioning the water with one more additives including an iron salt, an acid, and an oxidant until the water contains more ion than arsenic, is acidic, and has an ORP of about plus 600 mV. A reagent is then added to the conditioned water until it becomes basic and the water and additives are then reacted in a reaction chamber wherein iron and arsenic are co-precipitated in the form of iron arsenate and iron hydroxide or iron oxide. Treated water is then separated from the precipitate by settling of filtering.

Abstract: A method is set forth for the treatment of mixed oil and water flowing from a producing oil well. Certain salts may be formed by the mixture some of which will be soluble organic salts. The present process sets forth a method of treating the produced stream with low molecular weight amines and preferably amine quaternaries with strong acids so that the oil based salts are removed from the water phase and left with the oil for segregation, thereby permitting disposal of the produced water without creating a sheen on the produced water. Subsequent waste water treatment is avoided to remove traces of oil on the produced but separated water.

Abstract: A process for the removal of soluble polyvalent metal impurities from aqueous streams, the polyvalent metal selected from groups IIIA, IIIB, IVA, IVB, VA, VB, VIB, VIIB, and VIII in the periodic table of elements, is disclosed. The process comprises, in order:(1) dissolving (a) chitosan or a water soluble salt thereof and (b) a halogenating agent capable of converting chitosan to an N-halochitosan in an aqueous stream that (i) contains said polyvalent metal impurity as a cationic or complex anionic moiety and (ii) is at a pH of 2 to 5.5, wherein an effective amount of N-halochitosan is formed in said aqueous stream to remove said polyvalent metal impurity;(2) raising the pH of the aqueous stream to a pH greater than 6, the pH being sufficiently high to form an insoluble product containing the polyvalent metal impurity and said N-halochitosan; and(3) separating the insoluble product from the aqueous stream.

Abstract: Solutions such as for example groundwater, drinking water, extracting solutions and effluents contaminated with metals, radioactive species and organics, singly or in combination, are treated by first removing undesirable oxidizing agents from the contaminated solution. Then the contaminated solution is separately treated with aqueous solutions of ferrous sulfate and hydroxide, which precipitate substantially all of the contaminants. Next, the precipitate is treated with a flocculant and/or a coagulant to form an easily dewaterable and separable solid. The solid contaminants are readily removed from the cleansed solution. The process utilizes a novel combination of steps which maximizes contaminant removal, minimizes waste volume, and produces a recyclable solution and a manageable waste stream. The preferred hydroxide solutions are sodium hydroxide, calcium hydroxide, and ammonium hydroxide.

Abstract: Process for denaturating water-dilutable paints and solvent-based paints, wherein said paints are treated by washing with the assistance of an aqueous denaturation phase whose pH is from 4.5 to 7 and preferably from 5 to 6 and which contains an effective quantity of at least one denaturation agent consisting of an amine molecule of formula ##STR1## or of formula: ##STR2## in which the substituents R.sub.1 to R.sub.7, which may be identical or different, represent:a hydrogen atom,a radical of formula --O--Re in which Re is chosen from the group comprising hydrogen and a C.sub.1 to C.sub.4 saturated aliphatic hydrocarbon chain, it being understood that the substituents R.sub.5 to R.sub.7 are not simultaneously all hydrogen atoms,or of a hydrate or else of a salt of an organic or inorganic acid salt of said amine molecule, preferably a salt of sulfuric acid, phosphoric acid or hydrochloric acid.

Abstract: A process for removing color from a pulp and paper wastewater which comprises the following steps: (a) treating the wastewater with a reducing agent which is capable of inactivating color producing functional groups of the wastewater; and (b) treating the wastewater subsequent to step (a) with a polymer which is capable of removing color from the wastewater.

Abstract: The invention describes the use of molybdenum compounds in circulating waters of wet precipitators of spray coating units for detackifying and coagulating paints and/ or varnishes, waxes and other organic coating compositions, and a process for detackifying and coagulating paints and/ or varnishes, waxes and other organic coating compositions by means of molybdenum-containing coagulants.

Abstract: A process for selectively recovering dissolved heavy metals from a solution is disclosed that involves selectively reacting a xanthate with such dissolved heavy metals. Selective reaction of a xanthate with selected dissolved heavy metals is accomplished by conducting the reaction under conditions such that only some of the heavy metals react with the xanthate, to the exclusion of reaction with other dissolved heavy metals. Selectivity of the reaction is particularly influenced by the pH at which the reaction occurs. Typically, the reaction should occur at a pH below about 4.0. Xanthates, once reacted, can be separated from the heavy metal xanthate reaction product and recycled for use within the process. Purified heavy metal product can be produced if desired.

Abstract: A composition for the detackification and clarification of acid and alkaline paint and lacquer waste waters and paint spray booth wastes, comprising:an inorganic-organic and/or organic adduct alloy polymer composition having the formula:A.multidot.B.sup.+ .multidot.D.sup.+wherein:A=[(SiO.sub.2 /Me.sup.I.sub.2 O).sub.u Me.sup.II.sub.m Me.sub.m.sup.III(OH) p.sup.(SO 4.sup.) y.sup.(Aci) (2m+3n)-p-2y].sub.4wherer=1 to 98% bw;u=0 to 10% bw; ##STR1## where: x=0 to 98% bw; Z is a divalent substituted or unsubstituted aliphatic, cycloaliphatic, heterocyclic or aromatic radicalD.sup.+ (PQAM).sub.wwherew=2 to 98% b.w. of polyquaternized polymer (PQAM)Me.sub.m.sup.II is selected from the divalent cationic group comprising: Mg, Zn, Ca, and Fe.sup.2+m=0 to 5Me.sub.n.sup.III is a tri-or more valent metal selected from the group comprising: Fe, Al, and Al-Zn complexes;n=1 to 20Aci is selected from the monovalent anionic group comprising Cl.sup.-, Br.sup.-, I.sup.-, NO.sub.3 --, H.sub.2 PO.sub.4 --, CH.sub.3 COO.sup.-, OH.

Abstract: A method of recovering contaminants from suspension or solution in a liquor comprises the steps of forming a foam of the liquor, displacing said foam onto a drainage device to dry said foam and separate the liquor said contaminants being retained in the dried foam and the drained liquor being reduced in contaminant content.

Abstract: Effluent containing inks undergoes flocculation by the action of a flocculating agent, followed by the continuous centrifuging of the effluent consisting of an acceleration between 1,000 and 20,000 g, while avoiding an air-liquid interface during centrifuging.

Abstract: Wastewater contaminated with heavy metals is treated in a multi-stage process. In a first stage, wastewater is treated with an effective amount of calcium oxide and/or calcium hydroxide in the form of lime to adjust the pH so that various metals in the water become insoluble. Gypsum formation may also occur if sulfate ions are present in the wastewater. In a second stage, an effective amount of sodium carbonate is added in the form of soda ash to allow formation of calcium carbonate. In a third stage, a coagulant, preferably a polymer, is added to facilitate the formation of a sludge comprising heavy metals, gypsum and calcium carbonate. In a final stage, the pH of the resulting effluent may be adjusted with a suitable acid, such as hydrochloric acid, to attain acceptable discharge requirements. The sludge formed is substantially stable and dewatered and has low toxic metal leaching characteristics.

Abstract: A method for inhibiting calcium sulfate scale formation and deposition and/or dispersing iron from a feedstream passing through a reverse osmosis system which comprises the steps of: controlling the pH of the feedstream within the range between about 6.0 to about 7.0; controlling the temperature of the feedstream within the range between about 50.degree. to about 80.degree. F.; and adding a scale inhibitor and/or iron disperant to the feedstream in an amount between about 0.002 ppm per ppm hardness (as CaCO.sub.3) of the feedstream to about 0.005 ppm per ppm hardness (as CaCO.sub.3) of the feedstream, the scale inhibitor comprising a water-soluble organic phosphonate and an N-substituted acrylamide polymer containing an amide structure as follows: ##STR1## where R.sub.2 is hydrogen or methyl, R.sub.

Abstract: Methods of treating circulating water containing oversprayed, water-borne paint, such as in a paint spray booth operation, with aluminum salts such as aluminum chloride or polyaluminum chloride and a flocculant, resulting in removal of sludge from the paint spray booth water.

Abstract: A process for the precipitation of aqueous plastics dispersions containing polyvinyl alcohol, preferably from waste waters, and separation of the polymeric solids content, which comprises adding the following to the dispersion in order, with thorough mixing:a) a boric acid component,b) a basic compound for making the pH alkaline, thenc) an iron salt andd) a cationic polymeric polyelectrolyte, and isolating the precipitate which forms in the alkaline medium. The process according to the invention is advantageously applicable in all relevant sectors of technology and waste water treatment in which polymer dispersions containing polyvinyl alcohol are used or have to be disposed of, and where waste waters in which dispersions containing polyvinyl alcohol are present have to be processed. Degrees of clarification of more than 95% can be achieved.

Abstract: A novel method of treating circulating water containing over-sprayed, water-borne paint, such as in a paint spray booth operation, comprises adjusting the alkalinity of the paint spray booth water to between about 20 and 600 ppm, on a calcium carbonate basis, by adding a designated alkalinity source thereto, adding a cationic potato starch to the water, contacting the over-sprayed, water-borne paint with the alkalinity-adjusted paint spray booth water after addition of the cationic potato starch, adding an effective amount of a polymer floccing agent to the paint spray booth water, and removing resulting sludge from the paint spray booth water.

Abstract: Method for removing suspended solids from a stream of waste water for subsequent use as an animal feed, wherein bentonite and an anionic polymer are added to the waste water which is maintained within a predetermined pH range. No metallic salts or other materials unacceptable as food additives are added to the waste water stream to facilitate flocculation of the bentonite and suspended solids. The pH range, maintained from 3.5 to 9.0 and optimally from 4.0 to 5.0, facilitates the coagulation of the suspended solids without the use of the metallic salts or other such additives. Microscopic air bubbles are used to float the flocculated bentonite and solids to the surface. In some cases the materials may be floated by gravity forces alone without the use of air bubbles. These floated materials are removed by skimmers or other top-floating solids removing apparatus commonly known in the industry and rendered into animal feed products.

Abstract: A process is disclosed in which ink contained in a water-wipe solution used in the intaglio printing of security documents is recycled after being refurbished. The water-wipe solution is neutralized; the ink is separated by filtration and refurbished before being utilized.

Abstract: The invention provides a method for decolorizing an effluent stream from a pulp mill plant comprising the step of adding an effective amount of a decolorizing composition including a ferrous sulfate and a water-soluble cationic amine polymer.

Abstract: A method of treating BCTMP/CTMP wastewater to improve retention and purification of cellulose fiber suspension and clarification of the BCTMP/CTMP wastewater which comprises the addition of a cationic, water soluble coagulant having a molecular weight less than 15,000,000 in an amount of about 1 to about 300 ppm; and a high molecular weight flocculant selected from the group consisting of: nonionic polymers having a molecular weight in the range between about 500,000 to about 30,000,000, low charge cationic polymers having a molecular weight in the range between about 5,000,000 to about 30,000,000, and low charge anionic polymers having a molecular weight in the range between about 5,000,000 to about 30,000,000, in an amount of about 0.1 to about 100 ppm.

Abstract: A process for removing proteinaceous materials, fats and oils from food processing wastewater using a coagulant such as lignin or a halogen ion containing compound together with a flocculant such as a natural polymer such as a polysaccharide or synthetic polymer is described. The combination of lignin or halogen and polymer is effective for coagulating and flocculating proteinaceous materials, fats and oils in food processing wastewater at low pH.

Abstract: A paint detackification treatment for paint spray booths include a water soluble polymer which is a dicyanadiamide formaldehyde condensation product in combination with multivalent metal salt, preferably aluminum chlorohydrate. The composition is added to the overspray collection tanks and acts to detackify particles of paint which are collected in a water curtain. The combination of the dicyanadiamide formaldehyde and aluminum chlorohydrate permits a lower concentration of polymer to be used and also permits this detackification product to be used with a wide variety of aqueous and oil based paints.

Abstract: Phosphates which are dissolved or contained in suspension are substantially completely removed from a low-solids waste water which has been clarified. Precipitating and flocculating agents for transforming the dissolved phosphated to an undissolved form are added to the low-solids wate water and precipitation products and suspended matter are removed by microsieving through mesh openings in the range of about 10 to 150 .mu.m. Microsieving is preferably effected in two stages including a preliminary sieving through mesh openings from 60 to 150 .mu.m and a fine sieving through mesh openings from 10 to 80 .mu.m.

Abstract: A method of treating wastewater including a heat-curable (meth)acrylic monomer-containing composition, at temperature below that necessary to effect heat-curing of the composition. The wastewater may be produced by aqueous washing of porous parts impregnated with a sealant composition containing such monomer. The monomer-containing wastewater is (1) adjusted in pH to a value in the range of from about 8 to about 10, and (2) contacted with an effective amount of a reducing agent which is polymerizingly effective for the monomer, to yield corresponding polymer from the monomer. The wastewater is mixed with a cationic flocculating agent in sufficient quantity to flocculate the polymer in the wastewater, and the resulting wastewater is physically separated to recover a monomer- and polymer-reduced wastewater effluent which may be discharged to receiving waters.

Abstract: Poly(diallylamine) blended with poly(N-methylolacrylamide) effectively detackifies over-sprayed paint in the circulating water of a wet paint spray booth operation. After detackification the dispersed paint is flocculated with hydrolyzed polyacrylamide, the paint waste is removed, and the clarified water is recirculated back into the paint spray booth operation.

Abstract: A method of treating wastewater containing (meth)acrylic monomer, such as is produced by aqueous washing of porous parts impregnated with a sealant composition containing such monomer. The monomer-containing wastewater is (1) adjusted in pH to a value in the range of from about 8 to about 10, and (2) contacted with an effective amount of a reducing agent which is polymerizingly effective for the monomer, to yield corresponding polymer from the monomer. The wastewater is mixed with a cationic flocculating agent in sufficient quantity to flocculate the polymer in the wastewater, and the resulting wastewater is physically separated to recover a monomer- and polymer-reduced wastewater effluent which may be discharged to receiving waters.

Abstract: Method for treating drilling effluents containing ligno-sulfonates wherein, successively, sulfuric acid is injected in order to cause coagulation, a cationic polyelectrolyte is injected to cause a flocculation and solids are separated from the liquid by centrifugation or dewatering compaction.

Abstract: A method for treating wastewater having a pH of between about 0.1 and 14 and containing dissolved heavy metals, in which a substantial portion of the heavy metals is precipitated as crystallized solids embedded within an insoluble monoclinic calcium sulfate crystal to produce a purified effluent having a pH of between 8 and 9.

Abstract: A process for treating wastewater the improvement which comprises admixing with the wastewater at least 0.5 percent by weight of a solution consisting of hypochlorous acid having a pH of less than 3 to prepare disinfected wastewater having substantially no available chlorine residual.The novel process of the present invention provides rapid, intimate mixing of the highly pure, highly acidic hypochlorous acid solution with the wastewater stream to disinfect wastewater bodies while minimizing unwanted side effects. The process eliminates the need for storing and handling pressurized gaseous or liquid chlorine.

Abstract: A process for sanitizing impotable water the improvement which comprises admixing with the impotable water a solution consisting of hypochlorous acid containing at least 0.5 percent by weight of HOCl and having a pH of less than 3 to prepare potable water having an available chlorine residual.

Abstract: A method for reducing industrial or urban effluent COD is described, comprising treating said effluents with an aqueous solution of alkaline and/or ammonium salts or humic acids perpared by the dry oxidation of coal with oxygen or oxygen/nitrogen mixtures at a temperture of between 120 and 350.degree. C. at an oxygen partial pressure of between 0.1 and 10 ata for a contact time of between 15 and 600 minutes, followed by extraction of the crude oxidation product with an alkaline and/or ammoniacal solution, characterised in that said aqueous solution is fed into effluent, the pH of which has been previously adjusted to between 1 and 3.5, to the extent that the humic acid salts which exhibit flocculating action are in a concentration of less than or equal to 2000 mg/1 of effluent.

Abstract: A chelation process and apparatus for treating an acid solution, namely nitric acid photoengraving etchant, having a high concentration of magnesium and having a heavy metal contaminant produced by zinc leached during etching. The process requires adjusting pH of a batch quantity of the etch solution to a value permitting chelating to occur and mixing carbamic sodium salt hydrate chelating agent with the solution in quantity sufficient to cause precipitation from the solution of a carbamic salt compound precipitate of the contaminant, and separating the precipitate from the remaining solution by filter press for removal from the solution for safe environmental disposal. The remaining liquor is safely sewered. The apparatus is mobile for use on photoengraving premises.