Abstract: An improved unit for removal of nitrates from water is disclosed, which features a cylindrical tank containing a nitrate-adsorbing resin bed and a dip tube/water distributor assembly. The assembly comprises a dip tube extending from an orifice in the upper portion of the tank to a lower distributor assembly, and an additional backflush tube having an open end disposed near the lower distributor assembly and communicating with an upper distributor located beneath the surface of the resin. A water flow restrictor is provided in the lower distributor assembly, such that when water is passed downwardly through the dip tube in a backflush mode, some of the water is squirted into the additional backflush tube, so that the backflush water flows into the resin bed at both its lower and upper portions. In this way, the resin bed is more effectively regenerated by subsequent supply of a brine solution than if the rinse water were only injected at the lower portion of the resin bed.

Abstract: The present invention relates to a method and an apparatus for producing a waste package of radioactive waste containing particles of radioactive waste material of low modulus of elasticity, particles of radioactive waste material of high modulus of elasticity, and a solidifying agent in which the particles of radioactive waste material of low modulus of elasticity and the particles of radioactive waste material of high modulus of elasticity are fixed in an almost uniformly dispersed state. According to this invention, the radioactive waste generated from nuclear power plants can be greatly reduced in volume and also a waste package of radioactive waste with high strength and excellent water resistance can be obtained.

Abstract: An improved process for the biomethanation of an organic substrate includes treating the substrate in a first reactor to form organic acid anions, passing an aqueous preparation containing dissolved organic anions through an anion exchanger so that the organic acid anions are adsorbed and separated from the remainder of the aqueous preparation, desorbing the organic acid anions and passing the desorbed acids to a second reactor containing methanogenic bacteria which convert the acids to methane. In a preferred embodiment, a bicarbonate solution is produced in the second reactor and it is used to desorb the organic acid anions and regenerate the anion exchanger into the bicarbonate form.

Abstract: The process of the present invention comprises adding an alkaline earth metal hydroxide such as barium hydroxide to a radioactive liquid waste containing sodium sulfate as the main component to convert the latter into an insoluble alkaline earth metal salt such as barium sulfate, adding silicic acid to by-product sodium hydroxide to prepare water glass and solidifying the radioactive insoluble alkaline earth metal salt with the water glass. According to this process, exudation of radioactive substances from the solid can be prevented and the solid having a high durability can be obtained at a low cost.

Abstract: A water-insoluble pigment comprising a complex of a water-insoluble inorganic substrate exhibiting anion exchange properties, a water-soluble dye, and an anionic amphipathic material is disclosed.

Abstract: A scrubbing process for high feed concentrations of different materials in liquid streams.

Abstract: A water-insoluble pigment comprising a complex of an anion exchange material with a layered crystal structure and a water-soluble dye is disclosed. The anion exchange material may be represented by the general formula:[M.sub.x.sup.+1 Q.sub.y.sup.+2.Al(OH).sub.3 ](A.sup.-1).sub.d (A.sup.-2).sub.e (A.sup.-3).sub.f (A.sup.-4).sub.g.nH.sub.2 Owhere M is a metal element or elements each with a positive valence of 1; Q is a metal element or elements each with a positive valence of 2; A.sup.-1, A.sup.-2, A.sup.-3, and A.sup.-4 are each one or more exchangeable anions each having a negative valence of 1, 2, 3, and 4 respectively; and n, x, y, d, e, f, and g are real numbers greater than or equal to zero and satisfy the following:0<x+2y.ltoreq.1d+2e+3f+4g=x+2y0.ltoreq.n.ltoreq.

Abstract: A water-insoluble pigment comprising a complex of an inorganic water-insoluble anion exchange material and a water-soluble dye is disclosed. The anion exchange material may be represented by the general formula:[M.sub.1-x.sup.a Q.sub.x.sup.a+1 O.sub.y (OH).sub.z ](A.sup.-1).sub.d (A.sup.-2).sub.e (A.sup.-3).sub.f (A.sup.-4).sub.g.nH.sub.2 Owherein M is a metal element or elements each with a positive valence of a; Q is a metal element or elements each with a positive valence of a+1; a is 2, 3, 4 or 5; A.sup.-1, A.sup.-2, A.sup.-3, and A.sup.-4 are each one or more exchangeable anions each having a negative valence of 1, 2, 3 and 4, respectively; x is 0<x.ltoreq.0.5; and n, y, z, d, e, f, and g are real numbers greater than or equal to zero and satisfy the following:2y+z=a0<d+2e+3f+4g.ltoreq.x0.ltoreq.n.ltoreq.10provided that when y=0, a is not equal to 2.

Abstract: Rectifying the compressive strength and toxic waste levels of ground water passages is achieved through the formation of a type C fly ash screen reinforcement of the passage.

Abstract: A process for treating acidic process waste water containing SiF.sub.6.sup.2- is disclosed. The process is carried out by contacting the waste water with a strong base ion exchange resin and loading SiF.sub.6.sup.2- onto the resin. Phosphate ions are then removed from the waste water by raising the pH of the waste water to between about 5.0 and 7.0 and contacting the waste water with a strong base ion exchange resin and loading phosphate ions onto the resin.

Abstract: Fluorine or fluorine compounds dissolved at low concentrations in water are efficiently separated by use of hydrated rare earth oxides or insoluble hydrated rare earth salts, particularly hydrous rare earth fluorides or hydrous rare earth phosphates, as the adsorbent. By bringing fluorine dissolved water of pH 2-7 into contact with said adsorbent, fluorine is adsorbed on the adsorbent, and the adsorbed fluorine can be desorbed by contact with an alkali solution of pH 10 to 14 to regenrate said adsorbent. Also, by addition of a precipitating agent for fluorine to the desorbed solution, fluorine compounds can be separated by precipitation and the filtrate can be reused as the regenerating solution for the adsorbent.

Abstract: The specification discloses a novel calcium silicate water-treating agent exhibiting a superior ability to remove various kinds of phosphorus compounds or other environmental pollutants contained in wastewater, the calcium silicate water treating agent comprising a burned product which is prepared by burning a mixture containing as main constituents calcium compound, thermally decomposable to calcium oxide (CaO), and SiO.sub.2 -containing compound at a temperature of 1300.degree. to 1600.degree. C., the molar ratio of CaO/SiO.sub.2 of the resultant burned product being in the range of 1.5 to 5.0, preferably 2.0 to 4.0. In this water treating agent, SiO.sub.2 component may be partially replaced by Al.sub.2 O.sub.3 and/or Fe.sub.2 O.sub.3. A further water treating agent is prepared by heating the hydrate of the burned product prepared above at a temperature of 50.degree. to 700.degree. C.

Abstract: The invention relate to a process for reducing the wash water required by weakly basic anion exchangers containing primary and/or secondary amino groups when fed with water containing carbon dioxide; in accordance with the process the exhausted, weakly basic anion exchangers are treated with dilute aqueous mineral acids before being regenerated.

Abstract: This invention relates to a method of ion-exchange and/or adsorption, and to a method of producing pure water. More specifically, this invention relates to a method of ion-exchanging and/or adsorbing an unnecessary product or a useful product in a liquid to be treated. Concretely, this invention relates to a method of ion-exchange and/or adsorption and to a method of producing superpure water by first treating the liquid with an ion-exchange resin, and then treating the liquid with an ion-exchange fiber.

Abstract: A method for producing a metal ion exchanger with increased absorption and regeneration capabilities that comprises treating an ionically inert porous support with a solution of metal oxychloride. Said metal oxychloride precipitates within the pores of the support and bonds thereto regardless of the pH of the system. The ion exchanger is then used as a medium through which sea water or other brine solutions are passed and inorganic ions and trace organics selectively absorbed. The ion exchanger is easily regenerated after absorption through treatment with sodium hydroxide and hydrochloric acid and can be reused immediately.

Abstract: A process for the preparation of formulations of water-soluble organic dyes starting from an aqueous salt-containing suspension of the untreated dye and using membrane separation methods, which process comprises substantially freeing the aqueous suspension of the untreated dye from by-products and reducing the salt concentration by more than half in a first membrane separation treatment, then diluting the dye suspension in a further optional step and effecting deionization and concentration in a second membrane separation treatment and converting the concentrate so obtained into a liquid or solid commercial formulation. This multi-step membrane separation process, e.g. ultrafiltration combined with hyperfiltration, results in a high rate of permeation through the membrane and avoids operating problems caused by membrane clogging.

Abstract: Anion exchangers containing OH groups as exchange active groups are suitable for the regeneration of photographic developers.

Abstract: The present invention provides a process for reducing the nitrate content in water, wherein water containing nitrate is contacted with an anion exchanger containing chloride and/or bicarbonate ions to remove the nitrate, whereafter the exhausted anion exchanger is regenerated, the spent eluate either (a) being divided into two or more portions at least one of which is rich in sulphate and at least one of which is rich in nitrate, the sulphate-rich portion being dumped to drain or being passed to a reaction vessel or vessels in which sulphate ions present therein are precipitated out as calcium salt by the addition of a water-soluble calcium salt or by adding an aqueous slurry of calcium hydroxide and in which denitrification is carried out on the nitrate-rich portion by means of appropriate anaerobic bacteria, a carbon source for the bacteria also being introduced into the reaction vessel and pH correction being carried out, if necessary, or (b) in which reductions of the sulphate and nitrate ion concentratio

Abstract: An apparatus for effecting filtration, clarification and purification of liquid which comprises a housing containing a filter element made up of a plurality of layers of adsorbent material, comprising a porous, non-woven fibrous matrix in which is included an adsorbing agent for removing dissolved or suspended matter from the liquid, and a plurality of layers of liquid-permeable material. The layers of adsorbent material and liquid-permeable material are interdigitated in a stack between liquid impervious walls, and the flow of liquid through the filter element is along path generally parallel to the confronting surfaces of the layers of adsorbent material and liquid-permeable material. A process for removing dissolved, suspended or particulate matter from a liquid containing same, utilizing the filter apparatus, is also disclosed.

Abstract: A novel composition including an inorganic mixed metal oxides and partially hydrated oxides exhibiting anion exchange properties and a method of preparing the exchanger composition by coprecipitating hydroxides or hydrated oxides of a pair of metal elements such as aluminum and titanium, drying the mixed metal hydroxides or hydrated oxides, exchanging the anion of the mixed metal hydroxide or hydrated oxide for a nonvolatile anion such as a sulfate anion and calcining the mixed metal hydroxide or hydrated oxide to form a mixed metal oxide or partially hydrated oxide exhibiting anion exchange properties.

Abstract: A method of purifying cooling water used in nuclear reactors, which comprises contacting said cooling water with a hydrotalcite compound of the following formulaM.sub.1-x.sup.2+ M.sub.x.sup.3+ (OH).sub.2 A.sub.x/n.sup.n-. mH.sub.2 O (1)wherein M.sup.2+ represents a divalent metal cation, M.sup.3+ represents a trivalent metal cation, A.sup.n- represents an anion having a valence of n, and x and m satisfy the following expressions0<x<0.50.ltoreq.m<1or a calcined product thereof obtained by calcination at a temperature of up to about 900.degree. C.; and a purifying agent used therefor.

Abstract: Borate ions dissolved at low concentration in water are separated efficiently with the use of a hydroxide or hydrous oxide of a rare earth element as the adsorbent. By contacting a borate ion-containing water with the adsorbent, borate ions are separated by adsorption, and the adsorbent having adsorbed borate ions is desorbed and regenerated for reuse with a desorbing solution adjusted to pH about 2 to about 4 or pH about 12 to about 14.

Abstract: There is disclosed a process for producing chlorine and an alkali metal hydroxide from brines containing soluble, iodine-containing salts by the electrolysis of aqueous alkali metal chloride in an electrolytic cell comprising an anode compartment and a cathode compartment separated by a fluorocarbon cation exchange membrane and in which the alkali metal chloride fed to the anode compartment contains not more than 1 ppm, preferably not more than 0.4 ppm of soluble iodine-containing salts.

Abstract: An improved process for treating aqueous effluents and purge streams to selectively remove polluting elements such as iron, copper, lead and mercury therefrom is described. The procedure comprises contacting the effluent with a poly(dithiocarbamate) chelating agent whereby the polluting elements are absorbed. The resin is extracted with an acidic aqueous solution having a pH of from about 4 to about 6; and removing the resin. When this is done, the residual content of these polluting elements in the effluent is reduced to a level below EPA required levels so that the effluent can safely be discharged into the surrounding ecosystem. The poly(dithiocarbamate) resin containing the polluting elements can be disposed of, for example, by being deposited in an unsecured landfill.

Abstract: Disclosed is a method of reducing the charging tendency in a flowing non-aqueous liquid which has a dielectric constant of less than about 50, by passing the liquid through an ion exchange resin charged with a weakly polar active group. Also disclosed is a combination of a transformer cooled by flowing organic insulating liquid and an anionic ion exchange resin and means for passing the liquid through the resin.

Abstract: Sulfate impurities are removed from alkali metal chloride brine electrolysis cell effluent by diluting the effluent to an alkali metal chloride content of less than 150 grams per liter and then contacting the diluted effluent with a weakly basic anion exchange medium.

Abstract: A novel technique has been discovered for separating oxalate from urine and other biological fluids. The method involves mixing the fluid with an adsorbent to separate the oxalate from the fluids, washing the adsorbent-oxalate complex, and releasing the oxalate by reacting the complex with alkali. This technique provides accurate results and can easily be run in hospitals and clinical laboratories.

Abstract: The present invention relates to insoluble compositions, which are capable of removing metal (e.g. selectively) from solution (e.g. Fe.sup.3+ from a liquid nutrient medium so as to lower the Fe.sup.3+ content to less than 0.1 .mu.M); the insoluble compositions comprise: a suitable insoluble carrier and organic co-ordinating sites covalently fixed to the surface of said carrier, said co-ordinating sites being capable of chelating Fe.sup.3+, Th.sup.4+ and/or UO.sub.2.sup.2+.

Abstract: This invention is concerned with production and use of high surface area particulate matter by calcining a charge of clay mineral, feldspar, zeolite, coal ash, fly ash, pozzolan or volcanic ash for a time to develop fractures which increase the surface area of the particles. Vacuum calcining decreases the calcining time. The calcined matter desirably has an analysis including: calcium oxide, about 20-40 weight %; aluminum oxide, about 15-35 weight %; and silicon oxide, about 20-40 weight %.The calcined particulate matter can be used in the treatment of impure aqueous materials; the matter is denser than water and sludge settles rapidly and completely. The calcined matter interacts with heavy metal ions to form tightly bound sludge that is nonhazardous for landfill disposal. The calcined matter can be combined with conventual coagulants, flocculants, filter aids, or activated carbon to obtain a multipurpose treating agent.

Abstract: The invention describes a process for the preparation of stable aqueous solutions of water-soluble reactive dyes, starting from an aqueous solution or suspension of the crude reactive dye which is concentrated and at least partially desalted by a membrane separation process. The process of the invention comprises continuously replacing part of the water which is drawn off from the dyestuff solution or suspension during the membrane separation process with demineralized water, whereby the concentration of calcium and magnesium ions in the dyestuff solution does not exceed 0.01% by weight. The concentrated and desalted dyestuff solution is stabilized by addition of a polyphosphate or dihydrogen phosphate/polyphosphate buffer, and a component which improves the water-solubility of the dye is optionally added.The formulations so obtained are readily storable for several months in the temperature range from -10.degree. to +40.degree. C.

Abstract: There is described a method for preparing a cation exchanger to remove metals from liquids they are contained in, which comprises adding to a silicic acid medium with a molecular weight which is preferably lower than 50,000, such a base which brings said medium at least to pH 8, preferably about pH 10, and forming a precipitate that comprises said cation exchanger.

Abstract: Ionic solutes are removed from fluids under oxidizing conditions or conditions of high physical stress or shock by contacting the fluids with ion exchange resin beads having macroreticular structure. These beads have a particular resistance to such conditions, and are formed by functionalizing with ion exchange functional groups a copolymer of 4-25% polyvinylidene crosslinking monomer and 96-75% monoethylenically unsaturated monomer or monomers, suspension polymerized in a liquid which is a solute for the monomer mixture, which does not substantially swell the copolymer, and which is present with the polyvinylidene monomer in an amount sufficient to cause separation of the copolymer from the dissolved monomer.

Abstract: An improved process for the treatment of aqueous effluents containing strong anions such as sulphate, nitrate, chlorides and fluorides wherein the aqueous effluent is subjected to a biological purification process is described. According to the process, aqueous effluent such as those obtained by condensation of gases present in a coal gasification plant and containing these anions and others in a combined concentration of at least 2 mval/l and organic contaminants in a concentration of at least 1000 mg/l are subjected to the biological purification followed by separation of water from solids of the effluent. Thereafter, the water is subjected to anion exchange in an anion exchanger against hydrogen carbonate ions and at least part of the so-treated water is recycled to the aqueous effluent so as to be present therewith during the biological purification. By such a process the biological purification can be conducted at an optimum pH such as a pH in the range of 6 to 8. CO.sub.3 /HCO.sub.

Abstract: Reducing the content of iodine in an aqueous brine solution to less than 1 ppm prior to electrolysis in an electrolytic cell separated into an anode chamber and a cathode chamber by a cation exchange membrane improves the electrolytic performance thereof.

Abstract: The invention relates to a method for separating nitrate from waters containing a significant amount of sulfate ion. Nitrate removal is accomplished by passing the water to be treated through a bed of a strong-base anion exchange resin which is a tributyl amine derivative of a copolymer exemplified by styrene-divinyl benzene. The tributyl species has been found to have an unusually high selectivity for nitrate over sulfate and provides not only a high capacity for nitrate removal but also economies in regeneration due to the ability to operate with only a partially regenerated resin bed.

Abstract: A cationic adsorption agent which is obtained by reaction of(a) an amino compound which contains at least one amino group and at least one free or methylolated carbamide or thiocarbamide group, or a salt thereof, with(b) an aminoplast precondensate which does not contain amino groups.The novel adsorption agent is suitable in particular for removing anionic substances, such as acid dyes or reactive dyes, from aqueous solutions, especially from wastewaters.

Abstract: A process for the direct regeneration of acid resin using a nonaqueous eluant saturated with anhydrous acid.

Abstract: A process for purifying or working-up a mixture containing water, water-soluble salts, organic ions and organic solvents, particularly mixtures of water, NaCl, Na glycolate and aliphatic alcohols such as methanol or isopropanol, by separating the mixture into its components using acidic and/or basic ion exchangers, in particular, using weakly basic anion exchangers after optionally adjusting the pH of the mixture to an acid value. The process is especially suited for purifying liquid reaction media and/or washing media from the production of polysaccharides, such as cellulose ethers or starch ethers containing sodium-carboxymethyl group substituents, which are prepared from polysaccharides, an alkali metal hydroxide and monochloroacetate ions in a medium containing water and at least one organic solvent.

Abstract: Resins bearing picolylamine moieties selectively adsorb iodide ions from acidic aqueous solutions. The iodide can be readily eluted from the resin with base. Particularly useful resins are obtained by reacting chloromethylated styrene-divinylbenzene copolymers with N-(2-hydroxyethyl)-2-picolylamine or bis-(2-picolyl)amine.

Abstract: In order to absorb ions and corrosive products which accumulate in a hydraulic circuit during its operation, particularly a hydraulic circuit in an aircraft which operates to control the operation of the aircraft, a solid material is disposed within the liquid which circulates through the circuit which is capable of chemically fixing these ions or products at its surface. The solid material may comprise a corrodible grade of iron and it may be in the form of a type of sieve.

Abstract: The present invention provides the following:(a) An aluminophosphorus compound wherein the atomic ratio of P to Al exceeds 1:1 and having anion exchange properties.(b) A process for preparing such an aluminophosphorus compound comprising treating an aluminous compound, for example a zeolite, a clay, or alumina with a melt comprising a phosphate, for example ammonium dihydrogen orthophosphate, and removing excess phosphate from the compound thereby formed.(c) A process for at least partially removing anions from an aqueous solution which comprises contacting the aqueous solution containing the anions with the aluminophosphorus compound.(d) A process for the chromatographic separation of two anions in aqueous solution wherein the chromatographic stationary phase comprises the aluminophosphorus compound.

Abstract: A cationic adsorption agent which is obtained by reaction of(a) an amino compound which contains at least one amino group and at least one free or methylolated carboxamide group, with(b) an aminoplast precondensate which does not contain amino groups.The novel adsorption agent is suitable in particular for removing anionic substances, such as acid dyes or reactive dyes, from aqueous solutions, especially from wastewaters.

Abstract: An adsorbent, which has been prepared by mixing (a) one part by weight of (i) at least one member selected from the group consisting of hydrated ferrites of titanium, zirconium and tin or (ii) a mixture of the said hydrated ferrites(s) and at least one member selected from the group consisting of hydrated oxides of titanium, zirconium, tin and iron with (b) about 1/10 to 3 parts by weight of a thermosetting resin showing resistance to acids and alkalis such as an unsaturated polyester or polyurethane resin, followed by curing.The adsorbent can be used to adsorb a great variety of anions and cations and especially as an adsorbent for phosphate ions.The adsorbent shows excellent resistance to acids and alkalis, and can be subjected to repeated desorption and regeneration procedures without causing any deterioration of its adsorptive capacity, thus permitting its repeated usage over a long period of time.The adsorbent can be magnetically separated, and facilitates solid-liquid separation.

Abstract: Preparations and uses are shown for novel crystalline aluminates which conform generally to the empirical formulaMgA.sub.a.sup.v Z.sub.b.sup.v.nAl(OH).sub.3.mH.sub.2 Owhere A and Z represent negative-valence ions or radicals selected from the group comprising hydroxyl, halide, inorganic acid, and organic acid,n is a value of from about 1 to about 2,v is a negative valence of 1, 2, or 3,a and b each have values of from zero to 2,with (va)+(vb) equal to 2, andwith m being a value of zero or more.

Abstract: Preparations and uses are shown for novel crystalline aluminates which conform generally to the empirical formulaMgA.sub.a.sup.v Z.sub.b.sup.v.nAl(OH).sub.3.mH.sub.2 OwhereinA and Z represent negative-valence ions or radicals selected from the group comprising hydroxyl, halide, inorganic acid, and organic acid,n is a value of from about 1 to about 2,v is a negative valence of 1, 2, or 3,a and b each have values of from zero to 2, with (va)+(vb) equal to 2, and withm being a value of zero or more.

Abstract: Sulfite ions are removed from an aqueous liquid by decreasing the pH of the liquid to convert at least a portion of the sulfite ions to bisulfite ions and contacting the liquid with a macroreticular solid compound containing carbonyl groups that can form adducts with the bisulfite ions.

Abstract: An adsorbent, which is prepared by subjecting to curing a mixture consisting of (a) one part by weight of at least one member selected from the group consisting of titanium oxide hydrate, zirconium oxide hydrate and tin oxide hydrate and of (b) about 1/10 to 3 parts by weight of an epoxy, unsaturated polyester or polyurethane resin.The adsorbent can be used as an adsorbent for a great variety of anions and cations and especially as the adsorbent for phosphate ion.The adsorbent displays also improved chemical resistance, resistant to acids and alkalis, and can be subjected to repeated desorption and regeneration procedures without causing any deterioration of its adsorptive capacity, thus permitting the repeated usage over a long period of time.

Abstract: The present invention relates to a method of abstracting heavy metal ions from solution by contacting the solution containing heavy metal ions with a cross-linked vegetable protein, or a mixture of cross-linked vegetable proteins. The method may be used to separate a mixture of heavy metal ions in solution by selectively abstracting a particular heavy metal ion by contacting the particular heavy metal ion with a selected cross-linked vegetable protein.Preferred vegetable proteins are derived from wheat, rape seed, safflower seed, sun-flower seed or soya bean.

Abstract: A gas stream containing SO.sub.x and NO.sub.x compounds is first treated for SO.sub.x removal by absorbing the SO.sub.x components in an aqueous liquid absorbent comprising formic or oxalic acid and an alkanolamine containing a tertiary amine functional group. When spent, this absorbent is regenerated by subjection to an elevated temperature sufficient to produce sulfur and/or hydrogen sulfide. The SO.sub.x -purified gas recovered from the first absorption step is then treated for NO.sub.x removal by contact with a second liquid absorbent solution containing a ferrous chelate in an aqueous, acidic medium. This absorbent is regenerated by contact, under conditions of elevated temperature and pressure, and in the presence of added formate ion, with a catalyst comprising a water-insoluble substance containing one or more tertiary amine functional groups such that absorbed NO.sub.x components are converted to elemental nitrogen.

Abstract: Contaminants such as surfactants, antifoam agents, viscosifying agents, corrosion inhibitors, other agents used in tertiary recovery of enhanced oil recovery operations, and the like are removed from a contaminated feedstock stream by contacting said feedstock stream with an adsorbent selected from montmorillonite clays, amorphous silica, and mixtures thereof with one another and/or with bauxite. In a further aspect, the thus purified feedstock stream is hydrodesulfurized.