EP3390283A1

EP3390283A1 - Water treatment method, and associated module and facility

Info

Publication number: EP3390283A1
Application number: EP16820230.7A
Authority: EP
Inventors: Anne BREHANT; Angélique FABRE; Marc Philibert; Laurent GUEY
Original assignee: Suez Groupe SAS
Current assignee: Suez International SAS
Priority date: 2015-12-18
Filing date: 2016-12-16
Publication date: 2018-10-24
Also published as: WO2017103101A1; US10710905B2; FR3045591B1; AU2016369400B2; HK1252335A1; KR20180096732A; AU2016369400A1; SG11201805089RA; FR3045591A1; CN108367943B; US20180370818A1; CN108367943A; CL2018001613A1

Abstract

The present invention concerns water treatment methods allowing cations and anions to be extracted from an aqueous effluent by bringing said aqueous effluent into contact with a hydrophobic liquid phase, also comprising at least one step of bringing the effluent into contact with a hydrophobic solid membrane, in order to eliminate the residual hydrophobic liquid membrane in the treated effluent by coalescence on said hydrophobic solid membrane. The methods according to the invention comprise seawater desalination methods. The invention also concerns a desalination module and the facility associated therewith, characterised in that they comprise at least one coalescer.

Description

WATER TREATMENT METHOD, MODULE AND INSTALLATION

ASSOCIATED.

The present invention relates to water treatment processes for extracting cations and anions from an aqueous effluent by contacting said aqueous effluents with a hydrophobic liquid phase. The processes according to the invention comprise seawater desalting processes, in which calcium, sodium, potassium, chloride, sulphate and carbonate ions, and processes for removing metal ions, for example, will be extracted. metal cations derived from transition metals such as iron, gold, silver, copper, chromium, platinum, lead, tin, cadmium, cobalt, zinc, nickel, mercury, .... or alkali metals such as sodium, cesium In particular, the invention relates to a process for the desalination of water by contacting an aqueous effluent with a hydrophobic liquid membrane. The invention also relates to a module for implementing the methods according to the invention, more particularly a desalination module and its associated installation.

Especially for desalination processes for the production of drinking water from seawater, these processes are generally based on heat or membrane treatments. However, they induce high energy consumption. Therefore, many developments have been made over the past decade to reduce the energy consumption of reverse osmosis membrane installations (optimization of membranes, development of more efficient pumps and introduction of recovery loops). energy). However, the overall cost of this type of facility remains much higher than conventional processes for treating freshwater.

Liquid-liquid extraction (LLE) water treatment processes are innovative processes that extract cations and anions from water through phase transfer of these ions from the aqueous phase to a hydrophobic phase, which is then separated from the treated water and optionally regenerated. Such hydrophobic liquids may be, for example, ionic liquids, comprising one or more anionic and / or cationic surfactant salts which are liquid at ambient temperature. More generally, these hydrophobic liquids may be formulations comprising a or a plurality of hydrophobic liquid bases and one or more active molecules capable of transferring the anions or cations which it is desired to remove from the aqueous phase to the hydrophobic phase. These active substances may be dispersed or dissolved in a hydrophobic liquid base or in a mixture of hydrophobic liquid bases. The active molecules capable of transferring the anions or cations which it is desired to remove from the aqueous phase to the hydrophobic phase may be, for example, anionic surfactants (for extracting the cations), or cationic surfactants (for extracting the anions), or molecules capable of solvating or complexing cations or anions, such as, for example, crown ethers, cyclic oligo-mothers (calixarenes), or non-cyclic oligomers of phenol derivatives in the presence of crown ethers, or dithizones.

The hydrophobic liquid phases used are commonly referred to as "liquid membranes".

These methods do not use a solid membrane, and do not require back pressure to extract the ions from the water.

Thus, it is known from the prior art documents which describe water pretreatment units, in particular salt water, comprising a direct contact heat exchanger whose continuous or dispersed fluorinated phase comprises a fluorine liquid immiscible with water. water and density greater than 1, 25. According to the variants, the direct contact heat exchanger may be a heat exchanger and / or an ion exchanger. Indeed, depending on the fluorinated phase used, the transfer made between the fluorinated phase and the water to be treated may be a thermal transfer or an ion transfer or simultaneously, a thermal transfer and ionic.

However, even if the liquid membranes used in liquid-liquid extraction water treatment processes are very hydrophobic and immiscible with water, they still have a slight water solubility. As a result, the time course in these processes results in a transfer of the liquid membranes into the aqueous phase. These transfers can come from soluble compounds that migrate with time from the liquid membrane to water.

Microdroplets may also exit the system due to the following malfunctions: the uncontrolled emulsion of the liquid / water phases causes separation problems, during the treatment or regeneration operations, the liquid membrane is carried off into the treated water stream or into the regeneration brine flow, due to a Inadequate ratio of counterflow flow rates, wear of the liquid membrane leads to underperformance in the extraction of ions.

It then follows the following disadvantages: an additional cost related to the loss of the liquid membrane, which must therefore be replaced, the contamination of the treated water with traces of liquid membrane, the contamination of the brine by traces liquid membrane, the brine from the regeneration of the liquid membrane.

The invention therefore aims to eliminate all or part of the disadvantages mentioned above, recovering the loss of one of the phases in the other. In addition, it solves the problem of the sensitivity of current coalescence devices to the precipitation of salts in brines.

More particularly, the subject of the invention is a method for treating an aqueous effluent comprising the following steps: (a) Liquid-liquid extraction, by bringing the aqueous effluent into contact with a hydrophobic liquid membrane immiscible with the water, allowing the transfer of ions from the aqueous phase to the hydrophobic liquid phase,

(b) Separation of the aqueous effluent and the hydrophobic liquid membrane resulting from step (a); (c) bringing the effluent from step (b) into contact with a hydrophobic solid membrane, in order to removing residual hydrophobic liquid membrane in said effluent by coalescence on said hydrophobic solid membrane.

Optional features of the invention, complementary or substitution are set forth below. The hydrophobic liquid membrane may comprise at least one compound chosen from the category of anionic surfactants and / or cationic surfactants, and / or calixarenes, preferentially the calix [4] arenes, and / or crown ethers, preferably the 18-6 crown ethers, or 12-4 crown ethers or 15-5 crown ethers, and / or dithizones.

The anionic surfactants may be chosen from the salts of carboxylates, alkyl benzoates, carboxiimidates, alkoxides or dialkoxides, alkyl sulphates, alkyl sulphonates, ether sulphonates, sulphonyl imides, phosphine oxides, phosphinates and alkyl borates. The cationic surfactants may be chosen from alkylsulfonium, alkylammonium, alkylphosphonium, alkylimidazolium, alkyloxazaborolidinium and alkyloxazolidinium salts.

The separation step (b) may be a decantation step.

The hydrophobic solid membrane may comprise a material chosen from polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefms, polyvinyl chlorides, polyethylene terephthalates, polyolefin copolymers, polyetherketones and ceramics.

The hydrophobic solid membrane may be hollow fibers. According to one variant, the liquid-liquid (a) and separation (b) extraction step are carried out in a first treatment chamber, the treated aqueous effluent and the hydrophobic liquid membrane being extracted separately from the first enclosure of treatment at the end of steps (a) and (b), and the bringing into contact of the aqueous effluent from step (b) (thus treated), with a hydrophobic solid membrane, intervening after evacuation of the aqueous effluent treated outside the first treatment chamber.

According to another variant, the liquid-liquid extraction step (a) and the separation step (b) are carried out in a first treatment chamber, the treated aqueous effluent and the hydrophobic liquid membrane being extracted separately from the first chamber at the end of steps (a) and (b), the contacting of the aqueous effluent from step (b) (thus treated) with a hydrophobic solid membrane, intervening before the evacuation of the aqueous effluent treated outside the first treatment chamber. The step of bringing the aqueous effluent resulting from step (b) into contact with the hydrophobic solid membrane may be carried out in a substantially cylindrical contactor provided with a central channel and a hydrophobic solid membrane. composed of porous and hollow longitudinal fibers, so that the residual hydrophobic liquid membrane migrates radially to the inside of the fibers. Circulation of fluids within this contactor can be done co-current, countercurrent or cross flow.

The treatment process may further comprise a step (e) of contacting the hydrophobic liquid membrane resulting from step (b) with a hydrophilic solid membrane, in order to eliminate the residual effluent in the hydrophobic liquid membrane, by coalescence on said hydrophilic solid membrane.

The hydrophilic solid membrane may comprise a material chosen from polysulfones, polyvinylidene fluorides, polyvinylpyrrolidones, cellulose acetate, polyether sulphones, optionally modified or additivated, and ceramics. The method may further comprise a regeneration step (d) of the hydrophobic liquid membrane from step (b).

According to one variant, the hydrophobic liquid membrane extracted from the first treatment chamber is admitted into a second regeneration chamber where it is brought into contact with water, the regenerated hydrophobic liquid membrane and the water then being separated and discharged outside the chamber. the second chamber, and the regenerated hydrophobic liquid membrane is then brought into contact with a hydrophilic solid membrane after evacuation out of the second chamber so as to eliminate traces of water.

The hydrophobic liquid membrane resulting from the coalescence step may be reused in step (a) of the treatment process.

The treatment can be a water desalination treatment, in particular desalination of seawater.

The regeneration of the hydrophobic liquid membrane can take place between 70 and 90 ° C., preferably around 80 ° C. The pressure differential during step (c) of contacting with a hydrophobic solid membrane may be between 1 and 5 bar. The pressure differential during step (e) of contacting with a hydrophilic solid membrane may be between 1 and 5 bar.

The subject of the invention is also a treatment module by bringing an aqueous effluent into contact with a hydrophobic liquid membrane for implementing the method according to the invention, the module comprising at least one liquid extraction chamber - liquid, means for admission and discharge of the effluent, respectively in and out of said chamber, means for admission and discharge of the hydrophobic liquid membrane, respectively into and out of said enclosure, characterized in that it further comprises at least a first hydrophobic solid membrane coalescer in fluid communication with said enclosure by means of a first inlet nozzle in the coalescer made on the means for discharging the effluent from said enclosure to remove traces of hydrophobic liquid membrane residual in the aqueous effluent.

The liquid-liquid extraction chamber may comprise a liquid / liquid extraction column.

The liquid-liquid extraction chamber may comprise a mixer / settler or any other liquid-liquid extraction contactor.

The liquid-liquid extraction chamber and the first coalescer can form a single unit consisting of a membrane contactor. The modules according to the invention are suitable for the implementation of water treatment processes for extracting salts present in a large panel of aqueous effluents from the oil and gas industry, water from mining operations, leachates from landfills, wastewater from incineration plants.

The invention particularly relates to a desalination module by contacting an aqueous effluent with a hydrophobic liquid membrane for implementing the method according to one embodiment of the invention, the module comprising at least one enclosure desalting means, means for admission and discharge of the effluent, respectively in and out of said enclosure, means for admission and discharge of the hydrophobic liquid membrane, respectively in and out of said enclosure, characterized in it further comprises at least a first hydrophobic solid membrane coalescer in fluid communication with said enclosure by means of a first coalescer inlet tapping on the discharge means of the the effluent out of said enclosure, to remove traces of hydrophobic liquid membrane residual in the aqueous effluent.

Optional features of the invention, complementary or substitution are set forth below. The first coalescer may be in fluid communication by means of a second and a third outlet tap, with respectively means for admission and discharge of the hydrophobic liquid membrane, in and out of said enclosure.

The hydrophobic liquid membrane may comprise at least one compound chosen from the category of anionic surfactants and / or cationic surfactants, and / or calixarenes, preferentially the calix [4] arenes, and / or crown ethers, preferably the 18-6 crown ethers, or 12-4 crown ethers or 15-5 crown ethers, and / or dithizones.

The anionic surfactants may be chosen from the salts of carboxylates, alkyl benzoates, carboxiimidates, alkoxides or dialkoxides, alkyl sulphates, alkyl sulphonates, ether sulphonates, sulphonyl imides, phosphine oxides, phosphinates and alkyl borates.

The cationic surfactants may be chosen from alkylsulfonium, alkylammonium, alkylphosphonium, alkylimidazolium, alkyloxazaborolidinium and alkyloxazolidinium salts. The first coalescer may be a contactor of substantially cylindrical shape, provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers.

The materials constituting the hydrophobic solid membrane may be chosen from the list defined by polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefins, polyvinyl chlorides, polyethylene terephthalates, polyolefin copolymers, polyetheretherketones and ceramics.

The desalination chamber may comprise a liquid / liquid extraction column. The desalination chamber may comprise a mixer / decanter or any other liquid-liquid contactor. The desalination chamber and the first coalescer can form a single unit consisting of a membrane contactor.

The desalination module may furthermore comprise a second hydrophilic solid membrane coalescer in fluid communication with the desalination chamber of the first module by means of a first entry into the coalescer made on the means for evacuating the membrane. hydrophobic liquid out of said enclosure, to remove traces of aqueous effluent residual in the hydrophobic liquid membrane.

The second coalescer may be in fluid communication by means of a second and third outlet tap, with the means for admitting the aqueous effluent into the chamber of the first module.

The second coalescer may be a contactor of substantially cylindrical shape, provided with a central channel and a hydrophilic solid membrane consisting of porous and hollow longitudinal fibers. The materials constituting the hydrophilic solid membrane may be chosen from the list defined by polysulfones, polyvinylidene fluorides, polyvinylpyrrolidones, cellulose acetate, polyether sulfones, optionally modified or additive, ceramics.

According to a particular embodiment, the desalination module comprises a coalescer dedicated to desalination and provided with a contactor of substantially cylindrical shape, provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers, inlet means in the central channel of a mixture composed of the aqueous effluent and hydrophobic liquid membrane, the mixture being produced in a particular mixing unit, means for discharging the desalinated effluent out of the central channel, inlet and outlet means connected to a first hydrophobic liquid membrane recirculation loop within the longitudinal fibers.

The invention also relates to a desalination plant of an aqueous effluent, in particular seawater, characterized in that it comprises a first desalination module according to one of the embodiments of the invention. invention. Optional features of the invention, complementary or substitution are set forth below.

The installation may furthermore comprise a second hydrophobic liquid membrane regeneration module, the means for admission of the hydrophobic liquid membrane into the first desalination module of the aqueous effluent being in fluid communication with the evacuation means. the hydrophobic liquid membrane outside the second hydrophobic liquid membrane regeneration module, while the hydrophobic liquid membrane admission means in the second regeneration module are in fluid communication with the liquid membrane evacuation means hydrophobic out of the first desalination module.

The installation may furthermore comprise a third hydrophobic solid membrane coalescer in fluid communication with the regeneration chamber of the second module by means of a first inlet into the coalescer made on the brine discharge means. out of said enclosure, in order to remove traces of hydrophobic liquid membrane residually present in the brine.

According to a particular embodiment, the installation may furthermore comprise a second hydrophobic liquid membrane regeneration module, said second module comprising a regeneration coalescer having a substantially cylindrical contactor provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers, means for admission into the central channel of a mixture composed of fresh water from a water point and hydrophobic liquid membrane from the first module, means for discharging the brine out of the central channel, admission and evacuation means connected to a second hydrophobic liquid membrane recirculation loop inside the longitudinal fibers of the contactor.

The installation may furthermore comprise a fourth hydrophilic solid membrane coalescer in fluid communication with the regeneration chamber of the second module by means of a first input into the coalescer made on the membrane discharge means. hydrophobic liquid out of said enclosure, to remove traces of aqueous effiuent residual in the hydrophobic liquid membrane. The fourth coalescer may be in fluid communication by means of a second and third nozzle, with the means for admitting the aqueous effluent into the enclosure of the first module.

The fourth coalescer may be a contactor of substantially cylindrical shape, provided with a central channel and a hydrophilic solid membrane consisting of porous and hollow longitudinal fibers.

The materials constituting the hydrophilic solid membrane are selected from the list defined by polysulfones, polyvinylidene fluorides, polyvinylpyrrolidones, cellulose acetate, polyether sulfones, optionally modified or additive, ceramics.

Other advantages and particularities of the invention will appear on reading the detailed description of implementations and non-limiting embodiments, and the following appended drawings: FIG. 1 is a schematic representation of a detail of a FIG. 2 is a schematic representation of another detail of a coalescer according to the invention, FIGURES 3, 4, 5, 6, 7 are diagrammatic representations of embodiments of an installation. desalination according to the invention. The methods according to the invention comprise a liquid-liquid extraction step

(LLE) which consists of extracting cations and anions from the water by phase transfer of these ions from the aqueous phase to a hydrophobic liquid phase, which is then separated from the treated water and optionally regenerated.

The hydrophobic liquid phases used in the processes, modules and installations according to the invention are commonly referred to as "liquid membranes".

Such hydrophobic liquid membranes may be, for example, ionic liquids comprising one or more salts of anionic and / or cationic surfactants which are liquid at room temperature. More generally, these hydrophobic liquids may be formulations comprising one or more hydrophobic liquid bases and one or more active molecules capable of transferring the anions or cations that are desired remove from the aqueous phase the hydrophobic phase. These active substances may be dispersed or dissolved in a hydrophobic liquid base or in a mixture of hydrophobic liquid bases. The hydrophobic liquid bases can be, for example, hydrocarbon-based liquid bases, for example aliphatic hydrocarbons, preferably comprising between 6 and 22, preferentially between 10 and 18 carbon atoms, or aromatic hydrocarbons. These hydrophobic liquid bases may also be alkyl phenols, alcohols or fatty acids, or fatty esters, for example fatty esters of benzoic acid. These bases may also comprise substituted hydrocarbon chains, for example halogenated, for example fluorinated, to give the hydrophobic liquid a density greater than that of water. For example, hydrofluorocarbons or perfluorocarbons may be used as the hydrophobic liquid base.

The active molecules capable of transferring the anions or cations which it is desired to remove from the aqueous phase to the hydrophobic phase may be, for example, anionic surfactants (for extracting the cations), or cationic surfactants (for extracting the anions), or molecules capable of solvating or complexing cations or anions, such as, for example, crown ethers, calixarenes, or dithizones.

As anionic surfactant, salts of carboxylates, alkyl benzoates, carboxiimidates, alkoxides or dialkoxides, carboxiimidates, alkylsulfates, alkylsulfonates, ether sulfonates, sulfonylimides, phosphine oxides, phosphinates, alkylborates, etc. are preferably mentioned.

As cationic surfactant, mention may preferably be made of alkylsulfonium, alkylammonium, alkylphosphonium, alkylimidazolium, alkyloxazaborolidinium or alkyloxazolidinium salts, for example their salts formed with the anions tetrafluoroborate, chloride, hexafluorophosphate, mesylate, tosylate, triflate; .

The hydrophobic chains of these surfactants may be linear or branched, saturated or unsaturated, optionally substituted alkyl chains, for example by aryl or, for example, halogenated, in particular fluorinated or perfluorinated, substituents.

The molecules capable of solvating ions may be, for example, crown ethers, in particular crown 18-6 or crown 12-4 or crown 15-5 ethers, having a particular affinity for K +, Li + and Na + respectively. . these are also for example the calixarenes, in particular calix [4] arenes having a particular affinity for the ions Na +, Cu2 +, Zn2 +, or even the dithizones, having a particular affinity for lead and mercury. These molecules can also comprise various hydrocarbon substituents, aryl substituents, or linear, branched or cyclic, saturated or unsaturated, optionally substituted, for example halogenated, for example fluorinated or perfluorinated, alkyl substituents.

Hydrophobic liquid membranes suitable for water desalination processes, in which calcium, sodium, potassium, chloride, sulphate and carbonate ions, for example, comprise, for example, advantageously comprise one or more compounds chosen from: alkyl ammonium surfactants or alkyl phosphonium, having affinity for chloride ions, and / or crown ethers having affinity for sodium or potassium ions, and / or calixarenes having affinity for sodium and / or potassium ions, carboxylate, phopsphonate, sulphate surfactants phosphates, alkoxides, preferably phenolates, esters, preferentially benzoates, for their affinities with sodium and potassium cations.

Preferably, the liquid membranes have a density greater than that of water, a high hydrophobicity, and are regenerable at relatively low temperature (as an indication about 80 ° C). Preferably, the hydrophobic liquid membranes used in the desalination of seawater have the following characteristics: hydrophobic,

density higher than water,

interfacial tension sufficient to improve contact with water,

- sufficient affinity with the ions included in the list defined by Na ⁺ , Cl ^" , K ⁺ , Mg ^{z +} and SO4 ^2" , C03 ² \

ability to extract the complex salts of the hydrophobic liquid membrane (regeneration) at a temperature of about 80 ° C,

ability to extract complex salts from water at low temperature (room temperature). In order to gather all the above characteristics, the viscosity of the ion exchange liquids will generally be between 10 and 60 times the dynamic viscosity of the water.

Those skilled in the art will be able to adapt the formulation of the liquid membranes so as to obtain all or some of the above-mentioned characteristics and in order to extract the target cations or anions to be eliminated in the process.

The hydrophobic liquid membrane may be formulated from the active ingredients including methyl trioctyl / decylamine chlorides (Aliquat 336), trihexyl (tetradecyl) phosphonium chlorides (Cyphos IL 101), tributil (tetradecyl) phosphonium chlorides (Cyphos IL 167) in solvated or diluted phase in 10% decanol / kerosene. For more detail, the person skilled in the art will refer to the publication titled "Ionic liquids as a carrier for chloride reduction from brackish water using a hollow inflation liquid membrane" (Spain) and published by A. Fortuny et al in the journal " Desalination in 2013. The hydrophobic liquid membrane may be formulated from the active ingredients comprising mixtures of phosphine oxides: R ₃ PO + R ₂ R'PO + RR ' ₂ PO + R ₃ PO with R = CH ₃ (CH ₂ 7 and R = CH ₃ (CH ₂ ) ₅ (Cyanex 923) in the solvated or diluted phase in an aliphatic diluent (Exxsol D100) or aromatic diluent (Solvesso 200). For more detail, the person skilled in the art will refer to the publication entitled "Extraction and permeation studies of Cd (II) in acidic and neutral chloride media using Cyanex 923 on supported liquid membrane".

The hydrophobic liquid membrane may be formulated from the active principles comprising trioctyl / decylmethylammonium-bis (2,4,4-trimethilpentyl) (ALiCY IL) phosphinates, trioctyl / decylmethylammonium decanoates (ALiDEC IL), in the solvated or dilute phase in 10% decanol or kerosene. For more detail, the person skilled in the art will refer to the publication titled "Boron reduction by supported liquid membranes using ALiCY and ALiDEC ionic liquids asters" (Spain) and published by MT Coll in the journal "Chemical Engineering Research and Design" in 2014. The hydrophobic liquid membrane may be formulated from the active ingredients including hexafluoro-phosphates 1-alkyl-3-methylimidazolium, bis [(trifluoromethyl) sulfonyl] imides, bis [(perfluoroethyl) sulfonyl] imides, dicyclohexano-18-crown-6. For more detail, the skilled person will refer to the publication entitled "Ionic liquid anion effects in the extraction of metal by macrocyclic polyethers" (USA) and published by SL Garvey in the journal "Separation and Purification Technology" in 2014 The hydrophobic liquid membrane may be formulated from the active ingredients including acetates, tetrafluoroborates, hexafluorophosphonates, methylsulfates, dimethylphosphates, trihexyl (tetradecyl) phosphonium chlorides (Cyphos IL 101), Cocosalkyl (ECOENG500), alkyl-3-methylimidazolium, 1-allyl-3-methylimidazolium solvated phase or diluted in benzene, hexane, chlorobenzene, phenols, benzoic acids, benzamides. For more detail, the skilled person will refer to the publication entitled "Methods for recovery of ionic liquids - A review" (Republic of Korea) and published by NX. May in the journal "Process biochemistry" in 2014.

The hydrophobic liquid membrane may be formulated from the active ingredients including phenylglyoximes, P-tolylglyoximes, N '- (4'-Benzo [15-crown-5]) phenylaminoglyoximes, N' - (4'-Benzo [ 15-crown-5]) tolylaminoglyoximes, crown ether compounds + oximes. For more detail, the person skilled in the art will refer to the publication entitled "Liquid-liquid extraction of transition metal cations by glyoximes and their macrocyclic glyoxime ether derivatives" (Turkey) and published by N. Karapinar in the journal "Journal of Chemistry " in 2013.

The hydrophobic liquid membrane may be formulated from the active principles comprising the amines tris [(L) -alanyl-2-carboxamidoethyl]. For more detail, the person skilled in the art will refer to the publication entitled "Coordination of CU (II) and Ni (II) with a polydentate nitrogen ligand and synthesis of inoic liquids derived from betaine: Application to liquid extraction. liquid metal "(France) and published by A. Messadi in the journal" Thesis University of Reims Champagne Ardenne "in 2013.

The hydrophobic liquid membrane may be formulated from the active ingredients including Imidazolium, Ammonium, Pyridinium, Pyrrolidinium, Sulphonium, Phosphonium, tetrafluoroborates, hexafluorophosphates, trifluoroacetates, trifluoromethanesulfonates, bis (trifluorosulfonyl) imides, crown ethers, calixarenes, oxides trioctyl. The hydrophobic liquid membrane may be formulated from the active ingredients including tributyl (2-ethoxy-2-oxoethyl) ammonium, dicyanamides (Dca), bis (trifluoromethylsulfonyl) imides (NT £ 2). For more detail, the person skilled in the art will refer to the publication entitled "Task-speci fi cation ionic liquid with coordinating anion for heavy metal ion extraction: Cation exchange versus ion-pair extraction" (France) and published by A. Messadi in the "Separation and Purification Technology" magazine in 2013.

The hydrophobic liquid membrane may be formulated from the active ingredients including ethylaminediacetic acids. For more detail, the person skilled in the art will refer to the publication entitled "Removal of metal ions from aqueous solutions using chelating task-specified ionic liquids" published by Harjani in the journal "Journal of Materials Chemistry" in 2008.

The hydrophobic liquid membrane may be formulated from the active ingredients comprising 1-alkyl-3-, methylimidazolium hexafluorophosphates ([C n mim] [PF6], n = 4, 6, 8), with, as ligands, the crown ethers of the type 18-crown-6 (18C6), dicyclohexano-18-crown-6 (DCH18C6), 4,4 '- (5') - di- (tert-butylcyclohexano) -18-crown-6 (Dtbl8C6). For more detail, the person skilled in the art will refer to the publication entitled "Traditional extractants in nontraditional solvents: Groups 1 and 2 extraction by crown ethers in room temperature ionic liquids" and published by Visser in the journal "Industrial & Engineering Chemistry Research "in 2000.

The hydrophobic liquid membrane may be formulated from the active ingredients comprising R 1 = CH ₂ CH ₃ , R 2 = H, R 3 = CH ₃ 1-ethyl-3-methylmidazolium (emim +), R 1 = NH ₂ (CH ₂ ) ₃ CH ₃ R 2 = H, R 3 = CH ₃ N -aminopropyl-3-methylmidazolium (NH 2 pmim +), R 1 = (CH ₂ ) ₃ CH ₃ R 2 = H, R 3 = CH ₃ 1-butyl-3-methylmidazolium (bmim +), R 1 = ( CH ₂ ) ₅ CH ₃ , R 2 = H, R 3 = CH ₃ 1-Hexyl-3-methylmidazolium. For further details, those skilled in the art will refer to the publication entitled "Recent Advances in Ionic Liquid Membrane Technology" (Spain) and published by LJ Lozano in the journal "Journal of Membrane Science" in 2011.

The hydrophobic liquid membrane may be formulated from the active ingredients comprising 1-methyl-1- [4,5-bis (methylsulfide)] pentylpyrrolidinium

([MPS2PYRRO] +), 1-methyl-1- [4,5-bis (methylsulfide)] pentylpiperidinium ([MPS2PIP] +), 1-methyl-2-pentenepyrrolidinium ([MPTPYRRO] +), 1-methyl - 2- pentenepiperidinium ([MPTPIPJ +), 1-butyronitril. For more detail, the person skilled in the art will refer to the publication entitled "Extraction of noble metal ions from aqueous solution by ionic liquids" (Singapore) and published by JM Lee in the journal "Fluid Phase Equilibria" in 2012. The membrane hydrophobic liquid may be formulated from the active ingredients including dicychlohexano-18-crown-6, dithizone, 18-crown-6, 1- (2-pyridylazo) -2-naphthols, 1- (2-thiazolylazo) - 2-naphthols, tri-n-butylphosphates, 4,4- (5) - di (tert-butylcyclohexano) -18-crown-6, calyx [4] arene-bis (tertoctylbenzo-crown-6). For more detail, the person skilled in the art will refer to the publication entitled "The use of ionic liquids as" green "solvents for extractions" () and published by H. Zhao in the journal "Journal of chemical technology &biotechnology" in 2005.

The hydrophobic liquid membrane may be formulated from the active principles comprising the Calixarenes, calix [4] arenes bearing carboxymethoxygroups. For more detail, the skilled person will refer to the publication entitled "Calixarene-Based Molecules for Cation Recognition" (Germany) and published by R. Ludwig in the magazine "Sensors" in 2002.

The hydrophobic liquid membrane may be formulated from the active principles comprising the calix [n] arenes coupled to diazo groups p- (4-phenylazo) calix [4] arene (L1), p-phenylazocalix [6] arene (L2) ], phenol derivatives, 2,6-dimethyl-3-phenylazophenols (L3), 2- (5-bromo-2-pyridylazo) -5-diethylamino phenols (L4). For more detail, the person skilled in the art will refer to the publication entitled "Comparative studies on the solvent extraction of transition metal, cations by calixarene, phenol and ester derivatives" (Turkey) and published by H. Deligoz in the journal "Journal The hydrophobic liquid membrane may be formulated from the active ingredients including calixarene or resorcinarenes, calix [4] arenes containing carbonyl or ether oxygen atoms, in the solvated phase. or diluted in chloroform. For more detail, the skilled person will refer to the publication entitled "Calixarene and Resorcinarenes" (Poland) and published by W. Sliwa in the journal "Wiley-vch edition" in 2009.

The hydrophobic liquid membrane may be formulated from the active ingredients comprising the secondary amide derivatives calix [4] arene, the 5.1 l, 17,23-tetra (tert- butyl) -25,26,27,28-tetra (N-hexylcarbamoylmethoxy) calix [4] arene in solvated or diluted phase in benzonitrile, methanol. For more detail, the person skilled in the art will refer to the publication entitled "The effect of specifies solvent-solute interactions on complexation of alkali-metal cations by a lower-rim calix [4] arene amide derivative" and published by G. Horvat in the journal "Inorganic Chemistry" in 2013.

The hydrophobic liquid membrane may be formulated from the active ingredients comprising phosphoric acids Di-2-ethylhexyl, phosphoric acids Ethylhexyl (C16H3504P) solvated phase or diluted in kerosene. For more detail, the person skilled in the art will refer to the publication titled "Simultaneous removal of copper, nickel and zinc metal ions using a bulk liquid membrane system" (India) and published by R. Singh in the "Desalination" magazine in 2011. .

The hydrophobic liquid membrane may be formulated from the active ingredients comprising thiosalicylates tricaprylmethylammonium, [A336] [TS], benzoates tricaprylmethylammonium 2- (methylthio), [A336] [MTBA], benzoates tricaprylmethylammonium, [A336] [BA] , tricaprylmethylammonium benzoates, [A336] [BA], tricaprylmethylammonium. For more detail, the person skilled in the art will refer to the publication entitled "Ionic liquids for extraction of metals and metal containing compounds from communal and industrial waste wates" (Austria) and published by L. Fischer in the journal "Wates Research" in 2011. Figures 3, 4 and 5 show different embodiments of desalination plants. In each of the figures, there is a desalination chamber 10 and a regeneration chamber 20 in which an aqueous effluent is in contact with an ion exchange liquid (also called hydrophobic liquid membrane). The enclosures 10 and 20 respectively comprise intake means 11, 23 and discharge means 13, 22 of the aqueous effluent. They also comprise intake means 14, 21 and discharge 12, 24 of the ion exchange liquid. These admission and evacuation means may be ducts equipped with valves.

As referenced 40a, 40a ', 40b in FIGS. 3, 4 and 5 respectively and as shown in more detail in FIGS. 1 and 2, at least one of the modules incorporates a coalescer 40a, 40a', 40b in order to separating the hydrophobic liquid membrane from the effluent, in this case in a preferred application, seawater. The term "coalescer" is defined to mean a hydrophobic membrane contactor permitting a separation process between two phases, by means of a large contact surface of the microporous membrane which allows the coalescence of the droplets of the phase in the trace state in the microporous membrane. another phase. Coalescer also denotes an enclosure comprising a solid membrane, and into which a biphasic liquid mixture is introduced, for example a mixture of a hydrophobic liquid and an aqueous effluent, and in which the membrane has an affinity for one of the phases and not for each other. For example, a coalescer provided with a hydrophobic solid membrane is fed with an aqueous effluent containing traces of hydrophobic liquid. Traces of hydrophobic liquids will coalesce on the surface of the solid membrane. These coalesced droplets may migrate to the inside of the membrane, which may be porous, for example under the effect of a pressure differential.

To recover traces of water in a hydrophobic liquid, one proceeds in the same manner but using a coalescer provided with a hydrophilic solid membrane, which will be fed by a hydrophobic liquid containing water in trace amounts .

The membrane may be in the form of porous hollow fibers. The two-phase mixture is for example introduced outside the fibers. The liquid to be recovered in the trace state migrates inwardly of the hollow fibers of the membrane due to the porosity of the fibers, and possibly to a differential pressure between the inside and the outside of the fibers. The coalescer may also be fed from the inside of the fibers, counter-current, co-current or cross flow, by a liquid flow identical to that which is recovered in the trace state, and which will cause the coalesced droplets having migrated inside the fibers outside the coalescer. The coalescer may comprise a solid hydrophobic membrane, for example hollow porous fibers, for example materials selected from the list defined by polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefins, polyvinyl chlorides polyethylene terephthalates, polyolefin copolymers, polyetherketones and ceramics.

The coalescer may comprise a solid hydrophilic membrane, for example porous hollow fibers, for example materials selected from polysulfones, polyvinylidene fluoride, polyvinylpyrrolidones, cellulose acetate, polyether sulfones, ceramics. These materials may also have undergone surface modifications, or be additive in the mass, so as to enhance their hydrophilic nature. . As shown in detail in FIG. 1, the coalescer 40 has a substantially cylindrical shape and a housing 404 enclosing a grid 401 which holds a plurality of hollow fibers 403 extending longitudinally. The coalescer 40 is traversed by a central channel 402 connected to the outside by means of two openings 42 and 45, which are also in communication with the outside of the hollow fibers. The set of fibers, parallel to the central channel, is also in communication with the interior by means of two collectors 41, 43. The central channel serves to convey the phase to be treated inside the coalescer, this phase then wetting on the outer surface of the fibers.

As shown in detail in FIG. 2, the coalescer 40 may be integrated in a device by means of an inlet manifold 41 activated by a pump 44 ', and an outlet manifold 43. The outlet 43 of the channel can be connected to the input 41 via a recirculation loop comprising the pump 44 'and a valve 49 and / or can also be connected to another circuit by means of another pump 48 and another valve 47.

The general principle of operation of the coalescer in the invention will now be set forth. The liquid that it is desired to filter from the other liquid remaining in the trace state is introduced into one of the collectors 42, 45, the collector 45 becoming the inlet collector and the collector 42 becoming the outlet collector. . This liquid to be purified then flows longitudinally along the outer surface of the fibers. One introduces into one of the two openings 41, 43 the other liquid, so that it flows in the opposite direction (that is to say against the current) inside the fibers. The pressure of the liquid to be filtered is higher than the pressure of the other liquid. Because of the differential pressure (about two bars) and because of the hydrophobicity of the other liquid, the trace liquid passes through the porous wall of the fibers and joins the interior of the fibers to flow through of the other circuit comprising the two openings 41, 43.

In the case where it is desired to extract an aqueous effluent traces of hydrophobic liquid membrane, the solid membrane comprises hydrophobic hollow fibers and resistant to organic solvents. The materials will preferably be chosen from the list defined by polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefms, polyvinyl chlorides, polyethylene terephthalates, copolymers of polyolefins, polyetheretherketones, and ceramics.

In the case where it is desired to extract aqueous hydrophobic traces from a hydrophobic liquid membrane, the solid membrane comprises hollow fibers that are hydrophilic and resistant to organic solvents. The materials will preferably be chosen from the list defined by polysulfones, polyvinylidene fluorides, polyvinylpyrrolidones, cellulose acetate, polyether sulfones, optionally modified or additive, and ceramics. Mixtures or combinations thereof are possible as well as the use of surface-modified polymers, such as, for example, polymers chemically modified with one or more halogen groups by corona discharge or by ion incorporation techniques.

As shown in FIGS. 3, 4, 5 and 6, the desalination plant thus comprises a first module provided with a first desalination enclosure 10. The module is traversed by an aqueous effluent stream, for example from the seawater, entering the chamber 10 via the admission means 11, the fresh water evacuating via means 13. A flow of hydrophobic liquid membrane crosses against the enclosure 10, said flow being admitted in the enclosure 10 by the means 14 and being discharged from the enclosure 10 by the means 12.

Advantageously, the first module is an extraction module comprising, according to a first embodiment, an enclosure consisting of a liquid / liquid extraction column operating against the current. The extraction column contains a lining to increase the interface between the two phases (seawater and hydrophobic liquid membrane) and operate in a countercurrent mode. Thus, the salt water enters the bottom of the column and comes out at the top once desalinated, while the hydrophobic liquid membrane is introduced into the upper part through a distributor and leaves the column from below, loaded with salts. In the lower part of the column, zones of coalescence and decantation make it possible to hydraulically recover the hydrophobic liquid membrane by ion exchange and to separate it from water. According to another embodiment, the extraction module comprises an enclosure that can be a mixer / settler. Mixer / settler is understood to mean a set of stages mounted in series, each comprising a mixer in which the dispersion necessary for the transfer of material is created, a decanter which carries out the mechanical separation of the previously dispersed phases, a connection network ensuring the transfer countercurrent coalesced phases.

According to another embodiment, the extraction module comprises an enclosure that can be a stirred column or any other liquid-liquid extraction contactor as described in the engineer's art. J 2 756 "Liquid liquid extraction - Device description ".

As shown in FIG. 3, the enclosure 20 is in fluid communication with the coalescer 40a with hydrophobic solid membrane by means of a first quill 41 entering the coalescer made on the evacuation means 24. The coalescer is also in fluid communication by means of a second 45 and third 43 stitching of the coalescer, with respectively the evacuation means 13 of the fresh water out of the enclosure 10 and the admission means 21 of the liquid membrane hydrophobic in the enclosure 20.

The fresh water from the first module is sent to the collector 45 and then flows longitudinally along the outer surface of the fibers. The hydrophobic liquid membrane is introduced into the opening 41, so that it circulates countercurrently (in the opposite direction) inside the fibers. The pressure of the fresh water is greater than the pressure of the hydrophobic liquid membrane. Due to the differential pressure (about two bars) and because of the hydrophobic nature of the hydrophobic liquid membrane, the latter, in trace form, passes through the porous wall of the fibers and joins the interior of the fibers to join the main flow. of hydrophobic liquid membrane and flow through the other opening 43. The latter reintegrates the first module via the admission means 14.

Thus, the coalescer 40a makes it possible to extract from the flow of desalinated fresh water leaving the enclosure 10, the traces of hydrophobic liquid membrane which remained. Advantageously, the desalination plant comprises a second regeneration chamber 20 which makes it possible to desalt the hydrophobic liquid membrane, once the latter has recovered the salt initially contained in the seawater entering the water. first module. According to the same principle as that of the desalination module, the chamber 20 is traversed by a flow of the hydrophobic liquid membrane to be desalinated, which enters the chamber 20 via the admission means 21 themselves connected to the means of evacuation 12 of the chamber 10, the desalinated hydrophobic liquid membrane evacuating via the means 24 to reintegrate the first module via the admission means 14, and the inlet 41 of the coalescer 40a. A flow of fresh water crosses in the opposite direction the chamber 20, said flow being admitted into said module by the means 23 and being discharged (the water then became salted, or brine) out of the said module by the means 22.

Advantageously, the second module is a regeneration module consisting of a first embodiment in a liquid / liquid gravity extraction column. The extraction column contains a lining to increase the interface between the two phases (fresh water and hydrophobic liquid membrane) and operate in a countercurrent mode. Thus, the charged hydrophobic liquid membrane enters the upper part of the column and is subjected to salt extraction during its passage along the lining. It will then leave the column at the bottom and is routed as a liquid regenerated by the ion exchange to the first module. The fresh water enters the bottom of the column and is loaded with the salts released from the hydrophobic liquid membrane during its passage along the lining. This brine comes out of the column from above, loaded with salt. According to another embodiment, the regeneration module may be a mixer / settler. Mixer / settler is understood to mean a set of stages mounted in series, each comprising a mixer in which the dispersion necessary for the transfer of material is created, a decanter which carries out the mechanical separation of the previously dispersed phases, a connection network ensuring the transfer countercurrent coalesced phases.

According to another embodiment, the extraction module comprises an enclosure that can be a stirred column or any other liquid-liquid extraction contactor as described in the engineer's art. J 2 756 "Liquid liquid extraction - Device description ". This regeneration module may also advantageously comprise a direct contact heat exchanger which heats the regeneration column in order to minimize the overall heat loss occurring during desalination of the hydrophobic liquid membrane.

Advantageously, the temperature is brought between 70 and 90 ° C, and preferably around 80 ° C. According to a variant shown in FIG. 4, the desalination plant comprises a first chamber 10 and a second chamber 20 for regeneration which are in fluid communication in the same manner as the configuration of FIG. 3. On the other hand, the chamber 20 is now in fluid communication with a hydrophobic solid membrane coalescer 40a 'by means of a first coalescer inlet tap 45 on the brine discharge means 22 out of the second chamber 20. The coalescer is also in fluid communication by means of a second 42 and third 43 outlet connections of the coalescer, with respectively means for discharging the brine out of the second chamber 20 and with the inlet means 14 of the hydrophobic liquid membrane in the first chamber 10. The brine from the second module is sent to the collector 45 and then flows longitudinally along the outer surface of the fibers. The hydrophobic liquid membrane is introduced into the opening 41 so that it circulates in the opposite direction inside the fibers. The brine pressure is greater than the pressure of the hydrophobic liquid membrane. Due to the differential pressure (about two bars) and because of the hydrophobic nature of the hydrophobic liquid membrane, the latter, in trace form, passes through the porous wall of the fibers and joins the interior of the fibers to join the main flow. of hydrophobic liquid membrane and flow through the other opening 43. The filtered brine traces hydrophobic liquid is then conveyed to be treated while the recovered hydrophobic liquid flow is reintegrated into the first module via the means of admissions 14.

Thus, the coalescer 40a 'makes it possible to extract from the stream of brine leaving the second regeneration module, the traces of hydrophobic liquid membrane which remained.

According to another variant shown in FIG. 5, the desalination plant comprises a first desalination chamber 10 and a second regeneration chamber 20 which are in fluid communication in a manner identical to the configuration of FIGS. 3 and 4. the enclosure 10 is now in fluid communication with a coalescer 40b by means of a first and second tappings 41 (inlet), 43 (outlet) in the coalescer practiced on the intake means 11 of the seawater in the enclosure 10. The coalescer is also in fluid communication by means of a third and fourth tappings 45 (inlet), 42 (outlet) in the coalescer, with the discharge means 12 of the hydrophobic liquid membrane out of the chamber 10 of the first module.

The hydrophobic liquid from the enclosure 10 is sent to the collector 45 and then flows longitudinally along the outer surface of the fibers. Water is introduced into the opening 41 so that it circulates in the opposite direction inside the fibers. The pressure of the water is lower than the pressure of the hydrophobic liquid membrane. Due to the pressure difference (about two bars) and because of the hydrophobic nature of the hydrophobic liquid membrane, trace water passes through the porous wall of the hydrophilic membrane fibers and joins the interior of the fibers. to join the main flow of water and flow through the other outlet opening 43, to join the intake circuit 11 in the enclosure 10. The hydrophobic liquid from the coalescer is thus filtered traces of water and is returned via the output 42 to the second module to be desalinated.

Thus, the coalescer 40b makes it possible to extract from the flow of hydrophobic liquid membrane coming out of the first module, the traces of water that remained.

According to yet another variant shown in FIG. 6, the desalination plant comprises a first desalination chamber 10 and a second regeneration chamber 20 which are in fluid communication in a manner identical to the configuration of FIGS. 3, 4 and 5. on the other hand, the enclosure 10 is now in fluid communication with a hydrophilic coalescer 40b 'by means of a first and second branching 41 (inlet), 43 (outlet) in the coalescer made on the inlet means 11 of the seawater in the enclosure 10. The coalescer is also in fluid communication by means of a third and fourth port 45 (inlet), 42 (outlet) in the coalescer, with the discharge means 24 of the liquid membrane hydrophobic out of the chamber 20 of the second module.

The hydrophobic liquid coming from the enclosure 20 is sent to the collector 45 and then flows longitudinally along the outer surface of the fibers. Water is introduced into the opening 41 so that it circulates in the opposite direction inside the fibers. The pressure of the water is lower than the pressure of the liquid membrane hydrophobic. Due to the pressure difference (about two bars) and because of the hydrophobic nature of the hydrophobic liquid membrane, trace water passes through the porous wall of the hydrophilic membrane fibers and joins the interior of the fibers. to join the main flow of water and flow through the other outlet opening 43, to join the intake circuit 11 in the enclosure 10. The hydrophobic liquid from the coalescer is thus filtered traces of water and is returned via the output 42 to the first module.

Thus, the coalescer 40b 'makes it possible to extract from the flow of hydrophobic liquid membrane leaving the second module, the traces of water caused by the regeneration, which remained.

Regarding now the desalination process, whether in the case of desalination of seawater or the hydrophobic liquid membrane, the latter comprises at least the following steps:

(a) Liquid-liquid extraction, by contacting the seawater with a hydrophobic liquid membrane immiscible with water, allowing the transfer of ions from the aqueous phase to the hydrophobic liquid phase,

(b) Separation of the seawater and the hydrophobic liquid membrane from step (a),

(c) contacting the desalinated water from step (b) with a hydrophobic solid membrane, to remove residual hydrophobic liquid membrane in water desalted by coalescing on said hydrophobic solid membrane.

To formulate the hydrophobic liquid membrane, use is made of at least one compound chosen from the category of anionic surfactants and / or cationic surfactants, and / or calixarenes, preferentially the calix [4] arenes, and / or crown ethers, preferentially the 18-6 crown ethers, or 12-4 crown ethers or 15-5 crown ethers, and / or dithizones.

The separation step (b) may be a decantation step. The hydrophobic solid membrane is manufactured from a material chosen from polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefms, polyvinyl chlorides, polyethylene terephthalates, polyolefin copolymers, polyether ketones, as well as ceramics. A hydrophobic solid membrane consisting of hollow fibers is preferably used.

According to one variant, the liquid-liquid (a) and separation (b) extraction step are carried out in a first treatment chamber, while the aqueous effluent and the hydrophobic liquid membrane are extracted separately from the first chamber at the end of steps (a) and (b), and while the contacting of the aqueous effluent from step (b) with a hydrophobic solid membrane, occurs after evacuation of the aqueous effluent treated out of the first treatment chamber.

According to another variant, the liquid-liquid extraction step (a) and the separation step (b) are carried out in a first treatment chamber, whereas the treated aqueous effluent and the hydrophobic liquid membrane are extracted separately out of the first treatment chamber at the end of steps (a) and (b), and while the contacting of the aqueous effluent from step (b) with a hydrophobic solid membrane, occurs before the evacuation of the aqueous effluent treated outside the first treatment chamber.

The step of bringing the aqueous effluent from step (b) into contact with the hydrophobic solid membrane preferably takes place in a contactor of substantially cylindrical shape, provided with a central channel and a hydrophobic solid membrane constituted by of porous and hollow longitudinal fibers, so that the residual hydrophobic liquid membrane migrates radially to the inside of the fibers. Circulation of fluids within this contactor can be done co-current, countercurrent or cross flow. The treatment process may further comprise a step (e) of contacting the hydrophobic liquid membrane resulting from step (b) with a hydrophilic solid membrane, in order to eliminate the residual effluent in the hydrophobic liquid membrane, by coalescence on said hydrophilic solid membrane. The hydrophilic solid membrane is at least composed of a material chosen from polysulfones, polyvinylidene fluorides, polyvinylpyrrolidones, cellulose acetate, polyether sulphones, optionally modified or additivated, and ceramics.

The method may further comprise a regeneration step (d) of the hydrophobic liquid membrane from step (b).

The hydrophobic liquid membrane resulting from the coalescence step may be reused in step (a) of the treatment process. The regeneration of the hydrophobic liquid membrane can take place between 70 and

90 ° C, preferably around 80 ° C.

The pressure differential during step (c) of contacting with a hydrophobic solid membrane may be between 1 and 5 bar.

The pressure differential during step (e) of contacting with a hydrophilic solid membrane may be between 1 and 5 bar.

To summarize, the coalescer may be used when it is connected to the outlet of the aqueous effluent treated in the first module, to recover traces of hydrophobic liquid membrane which would have fortuitously dispersed in the form of droplets in the extraction column of the first module. This thus prevents the contamination of the aqueous effluent treated by the hydrophobic liquid membrane. The coalescer can also be used when it is connected to the second module, to recover traces of hydrophobic liquid membrane that would have incidentally dispersed in the form of droplets in the regeneration column of the second module. This thus avoids the contamination of the brine resulting from the desalination of the hydrophobic liquid membrane by the hydrophobic liquid membrane.

Alternatively, the coalescer may also be used when it is connected to the second module, to recover traces of water that would be incidentally dispersed in the form of droplets in the regeneration column of the second module. This thus avoids the contamination of the hydrophobic liquid membrane by the water used in the regeneration column.

The coalescer can be used when it is connected to the output of the hydrophobic liquid membrane of the first module, to recover traces of water that would escape the system due to an uncontrolled emulsion of the solvent / water phases or a bad one. coalescence / settling in the lower part of the extraction column extraction. This thus avoids weakening the thermal balance of the heat exchanger associated with the first module. This also makes it possible to conserve the capacity of the hydrophobic liquid membrane to carry out the ion uptake.

Alternatively, the invention also includes the case where the desalination chamber 10 and the coalescer form a single unit consisting mainly of a membrane contactor. This configuration is shown in Figure 7.

In this configuration, the step of coalescing the desalted Peffluent and / or the hydrophobic liquid membrane takes place in said enclosure 40, which is a hydrophobic solid membrane contactor, before the desulfated effluent and the hydrophobic liquid membrane are discharged out of the water. this enclosure. In this configuration, the effluent is desalinated by the hydrophobic liquid membrane during their contacting in the contactor, and, concomitantly, there is coalescence of the hydrophobic liquid membrane so as to eliminate its traces present in the effluent .

In other words, the liquid-liquid extraction is carried out (a) by contacting the aqueous effluent with a hydrophobic liquid membrane which is immiscible with water, allowing the transfer of ions from the aqueous phase. to the hydrophobic liquid phase, then, the aqueous effluent resulting from step (a) is brought into contact with with a hydrophobic solid membrane, in order to proceed concomitantly with steps (b) and (c).

More particularly and as shown in Figure 7, there is shown a desalination plant incorporating these particular modules. The plant comprises a desalting coalescer 40 having a substantially cylindrical shaped contactor provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers. The coalescer is provided with inlet means 45 in the central channel, exhaust means 42 out of the central channel, admission means 41 and evacuation 43 connected to a first recirculation loop communicating with the interior of the longitudinal fibers. This recirculation loop comprises a valve 49 and a pump 44 '.

The installation also comprises a regeneration coalescer 50 having a contactor of substantially cylindrical shape, provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers, admission means 55 in the channel central unit connected to the first recirculation loop and a water point 60. The regeneration coalescer 50 is also provided with evacuation means 52 out of the central channel, admission means 51 and evacuation means 52 connected to a central station. second recirculation loop communicating with the interior of the longitudinal fibers. This recirculation loop comprises a valve 59 and a pump 54. A tapping on this second recirculation puts it in communication with the inlet 45 of the desalination coalescer, by means of a line 44 also comprising a valve 57, a pump 58 and a water point 61.

In more detail, the hydrophobic liquid mixed with the water to be desalted are sent into the coalescer 40 through the collector 45 and then flow longitudinally along the outer surface of the fibers. The mixture between the water to be desalinated and the hydrophobic liquid membrane takes place in a mixing unit 45 'which may be a pump, a static mixer, or any other mixing device. The mixing unit is therefore connected as input to an inlet 44 dedicated to the hydrophobic liquid membrane and to an inlet dedicated to the water to be desalinated. The opening 41 of the hydrophobic liquid membrane is introduced so that it circulates in the opposite direction inside the fibers. The pressure of the hydrophobic liquid membrane is less than the pressure of the water + hydrophobic liquid membrane mixture. Due to the pressure differential (about two bars) and because of the hydrophobic nature of the hydrophobic liquid membrane, which therefore has affinity with the hydrophobic solid membrane, the hydrophobic liquid membrane contained on the outside of the fibers passes through the porous wall of the membranes. fibers (by taking with it the salt extracted from the water to be desalinated) and joined the interior of the fibers to join the main flow of hydrophobic liquid membrane and flow through the other outlet opening 43. Part of this flow is then returned to the coalescer 40 through the opening 41 and the other part is returned via the inlet 55 to the coalescer 50 to be desalinated. The salt-free desalinated water and the hydrophobic liquid membrane leave the coalescer 40 via the outlet 42. In order to regenerate the hydrophobic liquid membrane, a booster of water is made at 60 before admission into the coalescer 50 via a line 46 endowed with a pump 48 and a valve 47. The mixture water + hydrophobic liquid membrane is then sent into the coalescer via the inlet 55 and then flow longitudinally along the outer surface of the fibers. The hydrophobic liquid membrane is introduced into the opening 51 so that it circulates in the opposite direction inside the fibers. The pressure of the hydrophobic liquid membrane is less than the pressure of the water + hydrophobic liquid membrane mixture. Due to the pressure differential (about two bars) and because of the hydrophobic nature of the hydrophobic liquid membrane, which therefore has affinity with the hydrophobic solid membrane, the hydrophobic liquid membrane contained on the outside of the fibers passes through the porous wall of the membranes. fibers and joins the interior of the fibers to join the main flow of hydrophobic liquid membrane and flow through the other outlet opening 53. Part of this flow is then returned to the coalescer 50 through the opening 51 and the other part is returned via line 44 to the inlet 45 of the coalescer 40 as a regenerated hydrophobic liquid membrane. The brine (water concentrated in salts) leaves the coalescer 50 through the outlet 52.

In this configuration, the hydrophobic liquid membrane is desalinated by fresh water (becoming brine) when they come into contact in the contactor, and, concomitantly, the brine coalesces so as to eliminate its traces of the hydrophobic liquid membrane. The latter can be reused without there being alteration or loss.

The configuration according to which there is a single unit of the "membrane contactor" type, to ensure desalination by contacting an effluent with a hydrophobic liquid membrane, and coalescence, is particularly advantageous because of its compactness.

The desalinated effluent also offers an excellent quality of treatment insofar as its passage through the contactor synergistically makes it possible to extract both the hydrophobic liquid membrane and the salt trapped therein.

The embodiments described above being in no way limiting, it will be possible to consider variants of the invention comprising only a selection of features described, isolated from the other characteristics described (even if this selection is isolated within a sentence including these other characteristics), if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one characteristic, preferably functional without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art .

To summarize, the process for treating an aqueous effluent according to the invention makes it possible in particular to desalt an aqueous effluent by successively performing the three steps (a), (b) and (c) or by first carrying out the step (a) then steps (b) and (c) concomitantly. The method for treating an aqueous effluent according to the invention therefore comprises the following steps:

(a) Liquid-liquid extraction, by contacting the aqueous effluent with a water-immiscible hydrophobic liquid membrane, allowing the transfer of ions from the aqueous phase to the hydrophobic liquid phase, then, - (b) ) Separation of the aqueous effluent and the hydrophobic liquid membrane from step (a), then,

(c) contacting the effluent from step (b) with a hydrophobic solid membrane, in order to remove the residual hydrophobic liquid membrane in said effluent by coalescence on said hydrophobic solid membrane, or (a) Liquid-liquid extraction, by bringing the aqueous effluent into contact with a water-immiscible hydrophobic liquid membrane, allowing the transfer of ions from the aqueous phase to the hydrophobic liquid phase, then,

(b and c) bringing the aqueous effluent from step (a) into contact with a hydrophobic solid membrane in order to proceed concomitantly with steps (b) and (c).

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention. In addition, the various features, shapes, variants and embodiments of the invention may be associated with each other in various combinations to the extent that they are not incompatible or exclusive of each other.

Thus, it is possible to extend the invention to other liquid membranes, for other specific applications by changing the combinations of active molecules, cationic or anionic surfactant salts, or "cage" type ether crowns, calixarenes molecules. .... Their formulation can be adapted to extract salts present in a wide range of effluents from the oil and gas industry, water from mining operations, landfill leachates, wastewater from industrial plants. 'incineration.

Claims

A method of treating an aqueous effluent comprising the steps of:

(a) Liquid-liquid extraction, by contacting the aqueous effluent with a water-immiscible hydrophobic liquid membrane, allowing the transfer of ions from the aqueous phase to the hydrophobic liquid phase,

(b) Separation of the aqueous effluent and the hydrophobic liquid membrane from step (a),

(c) contacting the aqueous effluent from step (b) with a hydrophobic solid membrane, in order to remove the residual hydrophobic liquid membrane in said effluent by coalescence on said hydrophobic solid membrane,

Process according to claim 1, in which the hydrophobic liquid membrane comprises at least one compound selected from the category of anionic surfactants and / or cationic surfactants, and / or calixarenes, preferably calix [4] arenes, and / or crown ethers, preferentially the 18-6 crown ethers, or 12-4 crown ethers or 15-5 crown ethers, and / or dithizones.

Process according to one of Claims 1 to 2, in which the anionic surfactants are chosen from the salts of carboxylates, alkyl benzoates, carboxiimidates, alkoxides or dialkoxides, alkyl sulphates, alkyl sulphonates, ether sulphonates, sulphonyl imides, phosphine oxides, phosphinates and alkyl borates.

Process according to one of Claims 1 to 3, in which the cationic surfactants are chosen from alkylsulfonium, alkylammonium, alkylphosphonium, alkylimidazolium, alkyloxazaborolidinium and alkyloxazolidinium salts.

5. Method according to one of claims 1 to 4 wherein the step (b) of separation is a decantation step. Process according to one of Claims 1 to 5, in which the hydrophobic solid membrane comprises a material chosen from polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefms, polyvinyl chlorides, polyethylene terephthalates, copolymers of polyolefins, polyetherketones.

The method of any one of claims 1 to 6, wherein the hydrophobic solid membrane is porous hollow fibers.

Treatment process according to any one of Claims 1 to 7, characterized in that:

the liquid-liquid (a) and separation (b) extraction step are carried out in a first treatment chamber,

the aqueous effluent and the hydrophobic liquid membrane are extracted separately from the first treatment chamber at the end of steps (a) and (b),

contacting the aqueous effluent from step (b) with a hydrophobic solid membrane, occurs after evacuation of said aqueous effluent out of the first treatment chamber.

Treatment process according to any one of Claims 1 to 7, characterized in that:

the treated aqueous effluent and the hydrophobic liquid membrane are extracted separately from the first treatment chamber at the end of steps (a) and (b),

contacting the aqueous effluent from step (b) with a hydrophobic solid membrane, occurs before the discharge of said aqueous effluent out of the first treatment chamber.

10. Treatment process according to any one of claims 1 to 9, characterized in that the step of contacting the aqueous effluent from step (b) with the hydrophobic solid membrane is produced in a substantially cylindrical contactor provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers, and in that the residual hydrophobic liquid membrane migrates radially up to inside the fibers.

11. Treatment method according to any one of claims 1 to 10 further comprising a step (e) of contacting the hydrophobic liquid membrane from step (b) with a hydrophilic solid membrane, in order to eliminate the residual effluent in the liquid membrane, by coalescence on said hydrophilic solid membrane.

12. The method of claim 11 wherein the hydrophilic solid membrane comprises a material selected from polysulfones, polyvinylidene fluoride, polyvinylpyrolidones, cellulose acetate, polyether sulfones, optionally modified or additivés, ceramics.

13. The method of claim 1 further comprising a regeneration step (d) of the hydrophobic liquid membrane from step (b).

14. Treatment method according to claim 13, characterized in that:

the hydrophobic liquid membrane extracted from the first treatment chamber is admitted into a second regeneration chamber where it is brought into contact with water,

the regenerated hydrophobic liquid membrane and the water are separated and discharged out of the second enclosure,

the regenerated hydrophobic liquid membrane is brought into contact with a hydrophilic solid membrane after evacuation from the second enclosure.

15. Treatment method according to any one of claims 1 to 14, wherein the hydrophobic liquid membrane from the coalescing step is reused in step (a) of the treatment process.

16. Method according to one of claims 1 to 15 wherein the treatment is a desalination treatment of water, in particular desalination of seawater.

17. Desalting process according to claim 16, wherein the regeneration of the hydrophobic liquid membrane takes place between 70 and 90 ° C, preferably around 80 ° C.

18. Desalting process according to any one of claims 16 to 17, wherein the pressure differential during step (c) of contacting with a hydrophobic solid membrane, is between 1 and 5 bar.

19. Desalination module by contacting an aqueous effluent with a hydrophobic liquid membrane for carrying out the process according to one of claims 16 to 18, the module comprising at least one desalination chamber (10), means for admitting (11) and evacuating (13) effluent, respectively, into and out of said enclosure, means for admitting (14) and discharging (12) the hydrophobic liquid membrane, respectively, into and outside said enclosure, characterized in that it furthermore comprises at least a first coalescer (40a) in fluid communication with said enclosure by means of a first inlet tap (45) in the coalescer practiced on the means discharging the effluent from said enclosure, to remove traces of hydrophobic liquid membrane residual in the aqueous effluent. 20. Desalination module according to claim 19, characterized in that the coalescer (40a) is in fluid communication by means of a second (41) and third (43) outlet connections, respectively with the admission means and discharging the hydrophobic liquid membrane, in and out of said enclosure. 21. desalination module according to claim 19 or 20, characterized in that the hydrophobic liquid membrane comprises at least one compound selected from the category of anionic surfactants and / or cationic surfactants, and / or calixarenes, preferably calix [4 arenas, and / or crown ethers, preferentially the 18-6 crown ethers, or 12-4 crown ethers or 15-5 crown ethers, and / or dithizones.

22. desalination module according to claims 19 to 21, characterized in that the anionic surfactants are selected from carboxylate salts, alkyl benzoates, carboxiimidates, alkoxides or dialkoxides, alkylsulfates, alkylsulfonates, ether sulfonates, sulfonylimides, phosphine oxides, phosphinates, alkyl borates.

23. desalination module according to claims 19 to 22, characterized in that the cationic surfactants are selected from alkylsulfonium, alkylammonium, alkylphosphonium, alkylimidazolium, alkyloxazaborolidinium, alkyloxazolidinium salts.

24. desalination module according to any one of claims 19 to 23, characterized in that the first coalescer is a contactor (40a) of substantially cylindrical shape, provided with a central channel (402) and a hydrophobic solid membrane composed of porous and hollow fibers (403) longitudinal. 25. desalination module according to claim 24, characterized in that the materials constituting the hydrophobic solid membrane are selected from the list defined by polypropylenes, polyethylenes, polyvinylidene fluorides, polytetrafluoroethylenes, polyacrylonitriles, polyolefms, chlorides of polyvinyl, polyethylene terephthalates, copolymers of polyolefins, polyetheretherketones, and ceramics.

26. desalination module according to any one of claims 19 to 25, characterized in that the desalting chamber comprises a liquid / liquid extraction column.

27. desalination module according to any one of claims 19 to 25 characterized in that the desalination chamber comprises a mixer / settler.

28. desalination module according to any one of claims 19 to 25 characterized in that the desalting chamber (10, 20) and the coalescer form a single unit consisting of a membrane contactor.

29. desalination module according to any one of claims 19 to 28 characterized in that it further comprises a second coalescer (40b) in fluid communication with the desalination chamber of the first module (10) by means of a first entry into the coalescer practiced on the means for discharging the hydrophobic liquid membrane out of said enclosure, in order to eliminate traces of aqueous effluent residually present in the hydrophobic liquid membrane.

30. Desalination module according to claim 29, characterized in that the second coalescer (40b) is in fluid communication by means of a second and third outlet connections, respectively with the means of admission of the aqueous effluent into the enclosure of the first module (10).

31. desalination module according to any one of claims 29 or 30, characterized in that the second coalescer is a contactor (40b) of substantially cylindrical shape provided with a central channel (402) and a hydrophilic solid membrane composed of porous and hollow fibers (403) longitudinal.

32. Desalination module according to claim 24, characterized in that the materials constituting the hydrophilic solid membrane are selected from the list defined by polysulfones, polyvinylidene fluorides, polyvinylpyrrolidones, cellulose acetate, polyether sulfones, optionally modified or additive, ceramics. 33. Desalting plant of an aqueous effluent, in particular seawater, characterized in that it comprises a first desalination module according to any one of claims 19 to 32.

34. Desalting plant according to claim 33, characterized in that it further comprises a second regeneration module (20) of the hydrophobic liquid membrane, the inlet means (14) of the hydrophobic liquid membrane in the first module. for desalting the aqueous effluent (10) being in fluid communication with the means for discharging (24) the hydrophobic liquid membrane out of the second regeneration module of the hydrophobic liquid membrane, while the inlet means (21) ) of the hydrophobic liquid membrane in the second regeneration module are in fluid communication with the discharge means (12) of the hydrophobic liquid membrane out of the first desalination module.

35. Desalting plant according to claim 34, characterized in that it further comprises a third coalescer (40a ') in fluid communication with the regeneration chamber of the second module (20) by means of a first quilting. entering the coalescer practiced on the means for discharging the brine out of said enclosure, in order to eliminate residual hydrophobic liquid membrane traces present in the brine.

36. Desalination module by contacting an aqueous effluent with a hydrophobic liquid membrane for carrying out the process according to one of claims 16 to 18 and in which the liquid-liquid extraction is carried out, by placing in contact with the aqueous effluent with a hydrophobic liquid membrane immiscible with water, allowing the transfer of ions from the aqueous phase to the hydrophobic liquid phase, and then bringing the aqueous effluent coming from the step (a) with a hydrophobic solid membrane to proceed concomitantly with steps (b) and (c), characterized in that it comprises a desalting coalescer (40) having a substantially cylindrical contactor provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers, inlet means (45) in the central channel of a mixture consisting of the aqueous effluent and a hydrophobic liquid membrane and realized in a one (45 '), means for discharging (42) the desalinated effluent from the central channel, admission means (41) and discharge device (43) connected to a first hydrophobic liquid membrane recirculation loop (44 ', 49) within the longitudinal fibers.

37. A desalination plant for an aqueous effluent, in particular seawater, characterized in that it comprises a first desalination module according to claim 36.

38. Desalting plant according to claim 37, characterized in that it further comprises a second hydrophobic liquid membrane regeneration module, said second module comprising a regeneration coalescer (50) having a substantially cylindrical contactor , provided with a central channel and a hydrophobic solid membrane consisting of porous and hollow longitudinal fibers, means (55) for admitting into the central channel a mixture composed of fresh water from a point of water (60) and hydrophobic liquid membrane from the first recirculation loop (44 ', 49), means (52) for evacuating the brine from the central channel, admission means (51) and discharge (52) connected to a second hydrophobic liquid membrane recirculation loop (54, 59) within the longitudinal fibers of the contactor.