ITMI20102063A1 - PROCEDURE FOR THE TREATMENT OF WATER CONTAMINATED BY ORGANIC COMPOUNDS - Google Patents

Description

PROCEDURE FOR THE TREATMENT OF WATER CONTAMINATED BY ORGANIC COMPOUNDS

DESCRIPTION

The present invention relates to a process for the treatment of water contaminated by organic compounds.

More particularly, the present invention relates to a process for the treatment of water contaminated by polar and / or apolar organic compounds comprising sending said contaminated water to at least one nanofiltration unit.

Industrial wastewater that must be treated before its disposal or reuse often includes contaminated water including polar and / or non-polar organic compounds. These waters can come from a variety of industries such as, for example, aluminum and mulch production industries, chemical and / or petrochemical industries, automotive industries, oil industries.

In particular, the oil industries, both during extraction and during refining, produce significant quantities of water. For example, during the extraction both the production water is produced which is extracted together with the oil, and the injection water deriving from the return to the surface together with the hydrocarbons of the water pumped into the well to maintain pressure values at adequate levels. .

Typical contaminating compounds present in wastewater deriving from the petroleum industries, in particular in production water and in refinery wastewater (e.g., cooling water, washing water, refinery groundwater), and in wastewater deriving from petrochemical industries (e.g., cooling water, washing water, groundwater from petrochemical industries), are shown in Table 1.

Table 1

Treatments for the removal of the aforementioned contaminating compounds are known in the art. Examples of said treatments are reported in Table 2.

Table 2

The aforementioned physical and / or chemical treatments are generally carried out in “offshore” plants where spaces are limited and compact technologies can be used. However, said treatments, in addition to having high costs, can have some drawbacks. In fact, said treatments do not always turn out to be completely effective in removing both the aforementioned polar or apolar organic compounds, and the aforementioned dissolved minerals.

The aforementioned biological treatments are, on the other hand, generally carried out in "onshore" plants. These biological treatments, generally cheaper and more effective than the aforementioned physical and / or chemical treatments, however, are not always feasible in particular, in the presence of:

high salt concentrations which strongly inhibit the activity of the microorganisms used;

toxic substances for biomass (eg, benzene);

hardly biodegradable organic substances (e.g., MTBE).

Furthermore, these biological treatments generally require the management of large volumes of sludge produced.

Finally, further problems may arise from secondary pollution due to the use of chemical additives that can be used in order to control the aforementioned chemical, physical and / or biological treatments.

Treatments of contaminated water through membranes are described in the art. For example, Visvanathan and others in the article "Volume reduction of produced water generated from natural gas production process using membrane technology", published in "Water Science and Technology" (2000), Vol. 41, pg. 117-123, describe a process for the treatment of production water deriving from the natural gas production process, comprising sending said production water to a pre-treatment unit comprising an ultrafiltration (UF) membrane, or a nanofiltration membrane (NF), obtaining a permeate and a retentate; sending the permeate obtained from the pre-treatment unit to a treatment unit comprising a reverse osmosis (RO)] membrane. The aforementioned pre-treatment is said to be necessary in order to avoid fouling of the reverse osmosis (RO)] membrane.

Mondai and others in the article "Produced water treatment by nanofiltration and reverse osmosis membranes", published in "Journal of Membrane Science" (2008), Vol. 322, pg. 162-170, describe the treatment of co-produced production water during the production of oil or gas, by means of membrane by nanofiltration (NF) or by reverse osmosis [“reverse osmosis” (RO)]. In particular, the following membranes were tested:

NF 270: thin film composite membrane based on piperazine and semi-aromatic polyamide [nanofiltration (NF)];

NF 90 thin film composite membrane based on aromatic polyamide [nanofiltration (NF)];

BW 30 thin film composite membrane based on aromatic polyamide {reverse osmosis [“reverse osmosis” (RO)]}.

Tests have shown fouling of the membranes. The BW 30 reverse osmosis (RO) membrane produced the best quality permeate compared to the NF 270 and NF 30 nanofiltration (NF) membranes.

Ahmadun and others in the review "Review of technologies for oil and gas produced water treatment", published in "Journal of Hazardous Materials" (2009), Vol. 170, pg. 530-551, report different techniques for the treatment of production water deriving from the oil and gas industry. Among these, for example, treatment techniques using membranes for microfiltration (MF), membranes for ultrafiltration (UF), membranes for nanofiltration (NF), membranes for reverse osmosis [“reverse osmosis” (RO)] are described. In said review it is reported that the treatment of production water through a single technique is generally not able to give an effluent with the characteristics required by the regulations in force and that, for this purpose, it is preferable to subject said production water to two or more treatments.

US patent US 5,028,336 describes a method for treating water (e.g., production water deriving from the production of oil or gas) having a low pH and containing dissolved water-soluble organic electrolytes, which comprises: raising the pH of said water thus to obtain an alkalized water containing organic electrolytes dissolved in water; subject said alkalized water containing dissolved water-soluble organic electrolytes to nanofiltration in order to obtain (i) an aqueous retentate containing a higher concentration of dissolved water-soluble organic electrolytes and (ii) an aqueous permeate containing a lower concentration of dissolved water-soluble organic electrolytes; recovering said aqueous retentate containing a higher concentration of dissolved water-soluble organic electrolytes; and recovering said aqueous permeate containing a lower concentration of dissolved water-soluble organic electrolytes. The aforementioned treatment is said to be capable of effectively removing the dissolved water-soluble organic electrolytes present in said water.

However, the above methods may have some drawbacks. In fact, the aforementioned processes are not always able to give the desired results, in particular in the treatment of water contaminated by polar and / or apolar organic compounds, more particularly in the treatment of water contaminated by polar and / or apolar organic compounds in the presence of high saline concentrations (e.g., saline concentrations greater than or equal to 10,000 ppm).

The Applicant therefore posed the problem of finding a process for the treatment of water contaminated by polar and / or apolar organic compounds capable of giving good results, without requiring further treatments, even in the presence of high saline concentrations.

The Applicant has now found that by subjecting said contaminated water to a nanofiltration treatment, said treatment being carried out in the presence of nanofiltration membranes having specific characteristics, it is possible to effectively remove said polar and / or apolar organic compounds, even in the presence of high saline concentrations. . Said nanofiltration treatment allows to guarantee a high quality of the final effluent. In particular, said nanofiltration treatment makes it possible to obtain the removal of polar and / or non-polar organic compounds at levels defined by the regulatory limits provided for by Legislative Decree 152/2006 without the need for further treatments, with a consequent saving in treatment costs.

Therefore, the object of the present invention is a process for the treatment of water contaminated by polar and / or apolar organic compounds, comprising sending said contaminated water to at least one nanofiltration unit including at least one hydrophilic nanofiltration membrane, in which said hydrophilic nanofiltration membrane has an angle of contact with water lower than or equal to 45 °, preferably comprised between 25 ° and 40 °.

Said "contact angle" was measured as described by Geens and others in the article "Polymeric nanofiltration of binary water-alcohol mixtures: Influence of feed composition and membrane properties on permeability and rejection", published in "Journal of Membrane Science" ( 2005), Vol. 255, p. 255-264.

For the purpose of the present description and of the following claims, the definitions of the numerical ranges always include the extremes unless otherwise specified.

For the purpose of the present invention and of the following claims, the term "nanofiltration unit" means the entire apparatus necessary for carrying out the nanofiltration comprising, typically, at least one feeding tank, at least one feeding pump, at least one container (" vessel ") for nanofiltration including at least one nanofiltration membrane, at least one heat exchanger in order to keep the temperature of the supplied water constant. More details relating to said nanofiltration unit are reported below (Materials and Methods used).

In accordance with a preferred embodiment of the present invention, said contaminated water can be chosen from: production water deriving from oil or gas wells; injection water resulting from the return to the surface together with the hydrocarbons of the water pumped into the well to maintain pressure values at adequate levels; water deriving from refining; water from the petrochemical industries; groundwater from refining and / or petrochemical industries.

In accordance with a preferred embodiment of the present invention, said polar and / or apolar organic compounds can be selected from organic compounds having from 1 to 8 carbon atoms, preferably from 2 to 6 carbon atoms.

According to a preferred embodiment of the present invention, said polar organic compounds can be: alcohols such as, for example, methanol, ethanol, 1-propanol, iso-propanol, 1-butanol, iso-butanol, tert-butanol; ketones such as, for example, acetone, 2,3-butanedione, 3-hydroxy-2-butanone, methyl-ethyl-ketone, methyl-propyl-ketone, methyl-butyl-ketone, pentan-2-one, pentan-3- one; glycols such as, for example, ethylene glycol, diethylene glycol, triethylene glycol; carboxylic acids such as, for example, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, or their methyl substitutes; aldehydes such as, for example, acetaldehyde, butanaldehyde, pentanaldehyde, hexanaldehyde, or their methyl substitutes; or their mixtures.

In accordance with a preferred embodiment of the present invention, said non-polar organic compounds can be: halogenated solvents such as, for example, tetrachlorethylene (PCE), trichlorethylene (TCE), dichloroethylene (DCE), vinyl chloride (VC); aliphatic and / or aromatic compounds such as, for example, methyl-t-butylether (MTBE), ethyl-t-butylether (ETBE), benzene, toluene, ethylbenzene, xylenes (known as BTEX); or their mixtures.

In accordance with a further preferred embodiment of the present invention, said contaminated water can comprise salts such as: alkali or alkaline-earth metal salts such as, for example, chlorides, sulphates, carbonates, bicarbonates, sodium, potassium, calcium , magnesium, barium, strontium, iron; salts of heavy metals such as, for example, chlorides, sulphates, carbonates, bicarbonates, arsenic, chromium, antimony, selenium, mercury, cadmium, cobalt, nickel, lead, manganese, copper; or their mixtures.

In accordance with a further preferred embodiment of the present invention, said salts of alkali or alkaline-earth metals, or of heavy metals, can be present in said contaminated water in quantities greater than or equal to 1 ppm, preferably between 10 ppm and 20000 ppm, more preferably between 5000 ppm and 18000 ppm.

In accordance with a further embodiment of the present invention, said contaminated water can comprise other contaminants such as, for example, chemical additives usually used during well drilling.

In accordance with a preferred embodiment of the present invention, said polar organic compounds can be present in said contaminated water in quantities ranging from 1 ppm to 10000 ppm, more preferably between 2 ppm and 5000 ppm.

In accordance with a preferred embodiment of the present invention, said apolar organic compounds can be present in said contaminated water in quantities ranging from 1 ppm to 10000 ppm, more preferably between 2 ppm and 5000 ppm.

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can have a water permeability, measured at 22 ° C, between 0.5 l / (m x h x bar) and 5 l / (m x h x bar) , preferably between 1 l / (m x h x bar) and 3 l / (m x h x bar).

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can have a surface energy between 40 mN / m and 80 mN / m, preferably between 50 mN / m and 75 mN / m.

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can have a maximum operating temperature between 15 ° C and 50 ° C, preferably between 20 ° C and 45 ° C.

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can have a maximum operating pressure between 5 bar and 45 bar, preferably between 10 bar and 40 bar.

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can have a "molecular weight cut-off" (MWCO) between 150 dalton and 300 dalton, preferably between 200 dalton and 280 dalton.

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can have a maximum operating pH between 1 and 12, preferably between 1.5 and 11.

In accordance with a preferred embodiment of the present invention, said hydrophilic nanofiltration membrane can be selected from polymeric membranes comprising polyalkylsiloxanes, preferably polydimethylsiloxanes. Said polyalkylsiloxanes can be cross-linked or non-cross-linked, preferably cross-linked.

Hydrophilic membranes for nanofiltration which can be advantageously used for the purpose of the present invention are the products known under the trade names of SelRO <®> MPS-44 (series 2540, 4040, 8040) of Koch Membrane Systems.

The aforementioned hydrophilic nanofiltration membranes can take the form of homogeneous membranes, asymmetrical membranes, multilayer composite membranes, matrix membranes incorporating a layer of gel or a layer of liquid, or in any other form known in the art. Preferably, they are presented in the form of multilayer composite membranes comprising a base layer, a porous support layer and a layer comprising at least one of the above mentioned polymers. Basic layers useful for this purpose are, in general, flexible and highly porous woven or non-woven fabrics, comprising fibers including metal fibers, polyolefin fibers, polysulfone fibers, polyetherimide fibers, polyphenylene sulphide fibers, carbon fibers, or their mixtures; porous structures including glass, ceramics, graphite, metals, are equally useful. The porous support layer preferably has an asymmetrical porous structure. Said porous support layer can be produced, for example, from polyacrylonitrile, polysulfone, polyethersulfone, polyetherimide, polyvinylidene-fluoride, hydrolyzed cellulose triacetate, polyphenylene sulphide, polyacrylonitrile, polytetrafluoroethylene, polyethylene, polyvinylalcohol, other polyfluorins, copolymers or other polymers useful, or their mixtures.

The aforesaid hydrophilic nanofiltration membranes can be in the form of flat sheets, hollow fibers, tubular membranes, spiral wound membranes, or in other useful forms.

According to a preferred embodiment of the present invention, the specific flux (kg of permeate per square meter of surface of the hydrophilic nanofiltration membrane per hour) can be between 0.5 kg / (m x h) and 50 kg / (m x h ), preferably between 0.8 kg / (m x h) and 30 kg / (m x h).

In accordance with a preferred embodiment of the present invention, said contaminated water can be sent to the nanofiltration unit at a temperature between 10 ° C and 40 ° C, preferably between 15 ° C and 30 ° C.

In accordance with a preferred embodiment of the present invention, said contaminated water can be sent to the nanofiltration unit at a pH between 1 and 12, preferably between 2 and 10.

In accordance with a preferred embodiment of the present invention, said contaminated water can be sent to the nanofiltration unit at a pressure between 5 bar and 35 bar, preferably between 8 bar and 25 bar. Materials and methods used

Nanofiltration unit and hydrophilic nanofiltration membranes

The experimentation was conducted on a pilot plant (i.e. nanofiltration unit) equipped with a stainless steel "vessel" for nanofiltration capable of containing at least one hydrophilic membrane of spiral wound nanofiltration, with a diameter of 61 mm , an area of 1.6 m, and characterized by a high surface / volume ratio.

Figure 1 shows the scheme of the pilot plant (i.e. nanofiltration unit) used which is composed as follows:

a feed tank (1) having a capacity of about 3001; a pre-pump (2) with the purpose of providing a minimum inlet pressure; a high pressure feed pump (4);

- two pressure gauges (Pi) and (P2) with the purpose of checking the pressure between the two filters

(3);

a flowmeter (Fi) for measuring the supply flow rate;

a cartridge pre-filter (e.g., washable nylon) and a cartridge filter (e.g., polypropylene) (3);

- a pressure gauge (P3) with the purpose of checking the operating pressure;

a needle valve (6) for regulating the pressure across the membrane;

a stainless steel vessel for nanofiltration (5) comprising a hydrophilic nanofiltration membrane;

- a flow meter (F2) to measure the permeate flow rate;

a conductivity meter (C) for on-line measurement of the conductivity of the permeate; a plate heat exchanger (7).

In Figure 1 the permeate (8) and the retentate (9) are also reported.

The aforementioned plant works with a feed rate of 8001 / h and total recirculation: both the permeate (8) and the retentate (9) are in fact recycled to the feed tank (1) to keep their concentration constant during each test. .

The power supply is "cross-flow" and allows to reduce the phenomena associated with the "fouling" of the hydrophilic nanofiltration membrane, both chemical and physical. The operating temperature was set at 20 ° C and kept constant by the aforementioned plate heat exchanger (7).

Two working pressures were used: 10 bar and 20 bar and the pH of the solutions was kept between 6 and 7, unless otherwise specified.

The hydrophilic nanofiltration membrane used is a composite spiral wound membrane and consists of a series of pairs of flat membranes glued together on three sides and with the fourth side connected to a central channel for collecting the permeate; the membranes are then wrapped around this channel. The two membrane sheets are separated by a space net for permeate drainage. The mesh is also mounted on the feed side (between the pairs of membranes) and helps to create an additional turbulence that allows a decrease in the polarization concentration (theoretically the motion is laminar, with Re (i.e. Reynolds number generally included between 100 and 3000).

The surface / volume ratios are quite high, generally between 700 m <2> / m <3> and 1000 m <2> / m <3>.

The chemical-physical characteristics of the hydrophilic nanofiltration membrane used SelRO <®> MPS-44 (series 2540) (Koch) are shown in Table 3.

Table 3

For comparative purposes the Desal <®> -5-DL (General Electrics Osmotic) nanofiltration hydrophilic membrane was used: the chemical-physical characteristics are reported in Table 4.

Table 4

The degree of separation achievable with a membrane, and therefore its performance, with respect to a given solute is expressed by the percentage rejection:

R (%) = (1 - Cp / Cr) x 100

where Cpe Cr are the concentrations of the solute in the permeate and of the solute in the retentate, respectively.

The levies for the merger measures were made in equilibrium. Each trial lasted between 2 hours and 4 hours, with withdrawals every hour.

Analytical Methods

The waters were characterized with qualitative and quantitative analyzes of both the organic compounds present in the headspace (volatile organic compounds - method EPA 5021), and the organic compounds extracted with solvents (less volatile organic compounds - method EPA 3510 C).

The qualitative analysis for a preliminary identification of the prevalent organic compounds was carried out by gas chromatography associated with mass spectrometry (GC-MS).

The quantitative analysis was performed with two methods: one gas chromatographic (GC) (method EPA 8041 and method EPA 8015) which refers to the most representative classes of organic compounds, for example phenol-equivalent, and a chemical one for which organic compounds present are quantified in terms of total organic carbon (TOC) (EPA method 415.1).

The oxygenated low molecular weight organic compounds such as alcohols, glycols, aldehydes and ketones were quantified with the ASTM E202 and EPA 8260B methods.

The equipment used for the analyzes were the following:

“Purge and Trap” gas chromatograph (Agilent HP 6890) with a FID detector, split-splitless inlet and equipped with a DB WAXetr (PEG) capillary column (length 30 m, diameter 320 pm, film thickness 1 pm);

"Headspace" gas chromatograph (HP 5890 Π series with Agilent 7694 sampler) with an FID detector, split-splitless inlet and equipped with an HP-5 column (length 30 m, diameter 320 pm, film thickness 0.25 pm );

- IL550 TOC-TN (Hach) analyzer for TOC (Total Organic Carbon) analyzes;

conductivity meter (mod. 160, Amel Instruments) for measurements of conductivity and therefore of salt concentrations;

Instran EcaMon ÌOS polarograph, equipped with a three-electrode cell: working carbon electrode, auxiliary platinum electrode and Ag / AgCl reference electrode for the analysis of zinc, cadmium, lead and copper;

atomic absorption 220 FS Varian, with graphite atomization; pH-meter mod. 632 (Metrohm Herisan).

In order to better understand the present invention and to put it into practice, some illustrative examples are given below which should in no way be considered restrictive of the scope of the invention itself.

EXAMPLE 1

Salt rejection: comparison between two SelRO <®> MPS-44 and Desal <®> -5-DL nanofiltration membranes

Saline solutions in distilled water were used. Different one-component solutions were prepared with seven equimolar concentrations of each salt in order to compare the performance of the membranes on the different solutes at the same concentration: salts and concentrations are reported in Table 5.

Table 5

Figure 2 and Figure 3 show the results obtained in terms of rejection percentage by the SelRO <®> MPS-44 membrane in accordance with the present invention on sodium and magnesium chloride solutions at different molar concentrations and at two different operating pressures.

From the graphs it is possible to observe how the rejection of the SelRO <®> MPS-44 membrane towards chlorides is extremely high. In the presence of dilute solutions, the rejection of sodium chloride is slightly greater than that of magnesium chloride. As the concentration increases, the rejection decreases until it reaches an approximately constant value. For the MgCl2Γ trend, although less evident, it is the opposite: as the concentration increases, the rejection slightly increases until it exceeds that of sodium chloride already at a concentration of 0.007 mol / 1 and reaches constant values. The rejection of Na2S04 and MgS04 by SelRO <®> MPS-44 as a function of the concentration is constant and equal to 100% already at pressures of 10 bar.

By comparing it with the Desal <®> -5-DL membrane (comparative), the performances achieved with the membrane in accordance with the present invention are highlighted even more (i.e. the SelRO <®> MPS-44 membrane).

Figure 4 shows the results obtained in terms of the percentage of rejection by the Desal <®> -5-DL membrane on sodium and magnesium chloride and sulphate solutions at different molar concentrations. The graph shown in Figure 4 shows, especially with regard to chlorides, a clear worsening of rejection compared to the results obtained with the SelRO <®> MPS-44 membrane in accordance with the present invention.

EXAMPLE 2

Rejection of polar organic compounds: comparison between two SelRO <®> MPS-44 and Desal <®> -5-DL nanofiltration membranes.

We examined neutral polar organic pollutants with low and medium molecular weight in solutions containing only one component at a time at a concentration of 1000 ppm, at an operating pressure of 10 bar, at a temperature of 20 ° C and

at pH 7.

Table 6 shows the chemical-physical properties of the polar organic compounds used and the rejections obtained using the SelRO <®> MPS-44 nanofiltration membrane in accordance with the present invention.

Table 6

Table 7 shows the chemical-physical properties of the polar organic compounds used and the rejections obtained using the Desal <®> -5-DL nanofiltration membrane (comparative).

Table 7

The data reported in Table 7 show how the use of the Desal <®> -5-DL nanofiltration membrane (comparative) leads to a worsening of rejection compared to the use of the SelRO <®> MPS-44 membrane in accordance with the present invention (see Table 6).

EXAMPLE 3

Rejection of contaminating compounds using the SelRO <®> MPS-44 nanofiltration membrane

An experiment was conducted on solutions of contaminants in water of increasing complexity to study the performance of the membrane in the presence of multiple pollutants at the same time.

Table 8 shows the solutions used and the concentrations of the monitored compounds.

Table 8

<(1)>: methyl-t-butylether;

<(2)>: tert-butanol;

<(3)>: ethyl-t-butylether;

<(4)>: total dissolved solids expressed as salinity (*: in solution N ° 3 they indicate the concentration of NaCl);

<(5)>: wastewater from the refinery groundwater treatment plant.

As a reference for the experimentation, a wastewater from a refinery groundwater treatment plant (TAF) was chosen, in particular the aqueous stream at the outlet of an ultrafiltration section (UF) provided for Γ abatement of the dispersed oil . The wastewater was characterized by a COD ("Chemical Oxygen Demand") equal to 70 ppm due to the presence of: aromatic compounds (e.g., benzene and its derivatives), halomethanes, MTBE, ETBE, acetone, t-butyl alcohol, heavy metals, high saline content.

Four solutions in deionized water were prepared, numbered from 1 to 4 (shown in Table 8), containing in various ratios the main pollutants, i.e. those present in higher concentrations in the wastewater considered, i.e. solution 5 (reported in Table 8). The operating pressure was set at 10 bar.

Table 9 shows the results obtained in the nanofiltration tests using the SelRO <®> MPS-44 nanofiltration membrane in accordance with the present invention.

Table 9

From the data reported in Table 9 it is evident the high rejection of the hydrophilic nanofiltration membrane SelRO <®> MPS-44 in accordance with the present invention, against all organic contaminants present in the aqueous stream under examination. The removal is very high regardless of the synthetic or real matrix. There is no evidence of a competitive effect of the various organic components present in the solution, in fact there is no appreciable variation in the rejection capacity of the membrane towards the individual components and their mixture.

EXAMPLE 4 (comparative)

Rejection of contaminating compounds using the Desal <®> -5-DL nanofiltration membrane.

For comparative purposes, solutions 4 and 5 reported in Table 8, were subjected to nanofiltration using the Desal <®> -5-DL nanofiltration membrane (comparative): the results obtained are reported in Table 10.

Table 10

From the data reported in Table 10 it is evident how the use of the Desal <®> -5-DL nanofiltration membrane (comparative) decreases the rejection compared to the use of the SelRO <®> MPS-44 nanofiltration membrane in accordance with the present invention, with respect to all the organic pollutants present in the aqueous stream under examination.

Claims (37)

CLAIMS 1. A process for treating water contaminated by polar and / or non-polar organic compounds, comprising sending said contaminated water to at least one nanofiltration unit including at least one hydrophilic nanofiltration membrane, wherein said hydrophilic nanofiltration membrane has a contact angle with water less than or equal to 45 °. 2. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 1, wherein said contact angle with water is comprised between 25 ° and 40 °. 3. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 1 or 2, in which said contaminated water is selected from: production water deriving from oil or gas wells; injection water resulting from the return to the surface together with the hydrocarbons of the water pumped into the well to maintain pressure values at adequate levels; water deriving from refining; water from the petrochemical industries; groundwater from refining and / or petrochemical industries. 4. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which said polar and / or non-polar organic compounds are selected from organic compounds having from 1 to 8 carbon atoms. 5. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 4, in which said polar and / or non-polar organic compounds are selected from organic compounds having from 2 to 6 carbon atoms. 6. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which said polar organic compounds are: alcohols such as methanol, ethanol, 1-propanol, iso-propanol, 1-butanol, iso-butanol, tert-butanol; ketones such as acetone, 2,3-butanedione, 3-hydroxy-2-butanone, methyl-ethyl-ketone, methyl-propyl ketone, methyl-butyl-ketone, pentan-2-one, pentan-3-one; glycols such as ethylene glycol, diethylene glycol, triethylene glycol; carboxylic acids such as acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, or their methyl substitutes; aldehydes such as acetaldehyde, butanaldehyde, pentanaldehyde, hexanaldehyde, or their methyl substitutes; or their mixtures. 7. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which said non-polar organic compounds are: halogenated solvents such as tetrachlorethylene (PCE), trichlorethylene (TCE), dichloroethylene (DCE), vinyl chloride (VC); aliphatic and / or aromatic compounds such as methyl-t-butylether (MTBE), ethyl-tbutyl ether (ETBE), benzene, toluene, ethylbenzene, xylenes (known as BTEX); or their mixtures. 8. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, wherein said contaminated water comprises salts such as: salts of alkali or alkaline-earth metals such as chlorides, sulphates, carbonates, bicarbonates, sodium, potassium, calcium, magnesium, barium, strontium, iron; heavy metal salts such as chlorides, sulphates, carbonates, bicarbonates, arsenic, chromium, antimony, selenium, mercury, cadmium, cobalt, nickel, lead, manganese, copper; or their mixtures. 9. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which said salts of alkali or alkaline-earth metals, or of heavy metals, are present in said contaminated water in a greater quantity or equal to 1 ppm. 10. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 9, in which said salts of alkali or alkaline-earth metals, or of heavy metals, are present in said contaminated water in quantities ranging from 10 ppm and 20000 ppm. 11. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 10, wherein said salts of alkali or alkaline-earth metals, or of heavy metals, are present in said contaminated water in quantities ranging from 5000 ppm and 18000 ppm. 12. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, wherein said contaminated water comprises other contaminants such as chemical additives usually used during well drilling. 13. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which said polar organic compounds are present in said contaminated water in a quantity comprised between 1 ppm and 10000 ppm. 14. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 13, wherein said polar organic compounds are present in said contaminated water in a quantity comprised between 2 ppm and 5000 ppm. 15. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which said non-polar organic compounds are present in said contaminated water in a quantity comprised between 1 ppm and 10000 ppm. 16. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 15, in which said polar organic compounds are present in said contaminated water in a quantity comprised between 2 ppm and 5000 ppm. 17. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, wherein said hydrophilic nano filtration membrane has a water permeability, measured at 22 ° C, comprised between 0.5 l / (m x h x bar) and 5 l / (m x h x bar). 18. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 17, wherein said hydrophilic nanofiltration membrane has a permeability to water, measured at 22 ° C, comprised between 1 l / (m x h x bar ) and 3 l / (m x h x bar). 19. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, wherein said hydrophilic nanofiltration membrane has a surface energy of between 40 mN / m and 80 mN / m. 20. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 19, wherein said hydrophilic nanofiltration membrane has a surface energy comprised between 50 mN / m and 75 mN / m. 21. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to any one of the preceding claims, wherein said hydrophilic nanofiltration membrane has a maximum operating temperature between 15 ° C and 50 ° C. 22. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to claim 21, wherein said hydrophilic nanofiltration membrane has a maximum operating temperature between 20 ° C and 45 ° C. 23. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to any one of the preceding claims, in which said hydrophilic nanofiltration membrane has a maximum operating pressure between 5 bar and 45 bar. 24. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to claim 23, wherein said hydrophilic nanofiltration membrane has a maximum operating pressure between 10 bar and 40 bar. 25. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to any one of the preceding claims, wherein said hydrophilic nanofiltration membrane has a "molecular weight cut-off '(MWCO) between 150 dalton and 300 dalton . 26. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to claim 25, in which said hydrophilic nanofiltration membrane has a "molecular weight cut-off" (MWCO) between 200 dalton and 280 dalton. 27. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to any one of the preceding claims, wherein said hydrophilic nanofiltration membrane has a maximum operating pH between 1 and 12. 28. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 27, wherein said hydrophilic nanofiltration membrane has a maximum operating pH comprised between 1.5 and 11. 29. Process for the treatment of water contaminated by polar and / or apolar organic compounds according to any one of the preceding claims, in which said hydrophilic nanofiltration membrane is selected from polymeric membranes comprising polyalkylsiloxanes. 30. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any one of the preceding claims, in which the specific flow (kg of permeate per square meter of surface of the nanofiltration membrane per hour) is between 0, 5 kg / (m x h) and 50 kg / (m <2> x h). 31. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 30, wherein the specific flow (kg of permeate per square meter of surface of the nanofiltration membrane per hour) is between 0.8 kg / (m x h) and 30 kg / (m x h). 32. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any of the preceding claims, in which said contaminated water is sent to the nanofiltration unit at a temperature between 10 ° C and 40 ° C. 33. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 32, in which said contaminated water is sent to the nanofiltration unit at a temperature between 15 ° C and 30 ° C. 34. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any of the preceding claims, in which said contaminated water is sent to the nano filtration unit at a pH between 1 and 12. 35. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 34, in which said contaminated water is sent to the nanofiltration unit at a pH between 2 and 10. 36. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to any of the preceding claims, in which said contaminated water is sent to the nanofiltration unit at a pressure between 5 bar and 35 bar. 37. Process for the treatment of water contaminated by polar and / or non-polar organic compounds according to claim 36, in which said contaminated water is sent to the nanofiltration unit at a pressure between 8 bar and 25 bar.