ES2392235A1 - Method of cleaning, sterilization and disinfection for covered membranes with at least one film of at least one hydrophilic polymer. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Cleaning method, sterilization and disinfection for membranes coated with at least one film of at least one hydrophilic polymer. The present invention relates to a method of cleaning, sterilization and disinfection of membranes, preferably of semi-permeable hydrophobic type, which are coated with at least one film composed of at least one hydrophilic polymer, preferably selected from catecholamine, catecholamine derivatives, polyester, polyester derivatives and a combination thereof, said cleaning method comprising at least injecting a cleaning agent to the membrane selected from hot water, steam, superheated water or a mixture of the latter two. Preferably, the cleaning agent is injected at a temperature of at least 85ºC when it is hot water, and at least 100º c, more preferably 105º c, when it is water vapor, superheated water or a mixture of both. The membranes on which the cleaning and disinfecting agent is injected may be coated with a second film of at least one hydrophilic polymer similar to the first, although more preferably the first film is catecholamine and the second is polyester. (Machine-translation by Google Translate, not legally binding)

Description

CLEANING, STERILIZATION AND DISINFECTION METHOD FOR MEMBRANES COATED WITH AT LEAST ONE FILM OF AT LEAST A HYDROPHILIC POLYMER TECHNICAL SECTOR

The present invention is included in the field of the treatment of fluids and especially of waters, such as the purification of waters with a low contaminating load or of residual waters, specifically in the treatment by means of membrane filtration and more specifically it is related

with

the systems of cleaning of said membranes after its

job

in this kind of processes.

STATE

OF THE TECHNIQUE

Recently,

I know he has published in the magazine Science a

interesting

discovery accomplished by H. read et to the. (H.

Lee, P.E. Messersmith, Science 318,426 (2007)), which is based on the ability of certain substances secreted by certain species of mollusks, mussels among others, to fix the individual to almost any surface in the marine environment with a surprisingly effective level of adherence.

The molecules generated by the mussel spontaneously polymerize to the natural pH of seawater, acting as an effective adhesive that fixes the mussel to rocks, paints, concretes, steels, plastic pipes, etc. found in the marine environment. This substance has been found to belong to the catecholamine family and to be a neurotransmitter and precursor to other neurotransmitters in mammals. Catecholamines include epinephrine, norepinephrine, dopamine, and phenylethylamine, which contain a catechol group and an amino group and are synthesized from the amino acid tyrosine. These products act as surprisingly effective adhesives.

The discoverers of this action focused their work on a specific catecholamine, polydopamine, one of the

base products of this "natural adhesive". This molecule, or similar molecules, have the ability to polymerize each other, quickly and efficiently in the appropriate aqueous medium by fixing to the surface of almost anything. In this way they fix certain prominences of these molluscs to the surfaces to which they are attached, acting as an effective adhesive that attaches to the mentioned prominences and to the surface that supports them.

Additionally, the researchers showed the great reactivity of the polymer thus formed against third molecules (eg polymers with reactive groups such as amines, thiols and other groups, or even metals present in the water in the form of metal salts etc.) with which they would subsequently come into contact under the appropriate pH conditions

(fundamentally). This can cause the initially created polydopamine to be coated with a second product that may be of interest for a given industrial application.

Applications that are especially useful are, for example, semi-permeable membrane coatings such as nanofiltration or reverse osmosis and, especially, particle filtration membranes are microfiltration (MF) or ultrafiltration

(PHEW). This coating can affect (i.e. be performed on) the outer and inner surface of the membrane and even the pores that can be coated initially with a catecholamine, and later with a

polyether,

how the polyethylene glycol (PEG), the

polypropylene glycol

(PPG) or with any other polyether

Similary

or molecule highly hydrophilic than prevent the

proliferation

of lifetime organic or matter organic in the

surface

treated.

Indeed, one of the limitations of filter membranes in general and especially those of MF and UF in their

Filtration cycle is the fixation in them of amino acids, proteins, hydrocarbons, bacteria, fungi, and a long etcetera of organic matter, living or not, that contaminates them, damaging their filtration capacity. This contamination occurs not always reversibly by conventional membrane washes, especially those with MF or UF pore size.

Currently, the membranes of these latter types are washed by countercurrent water return, by air agitation, and by the use of chemical reagents such as soaps, acidic or caustic solutions, oxidants, or molecules such as EDTA acid, which applied with greater or lesser concentration and frequency they regenerate or clean the membranes of their deposits, with which a new filtration cycle begins.

Naturally, the fact that the surface and pores of a membrane are covered with catecholamine

(including epinephrine, norepinephrine, dopamine, and phenylethylamine), which is itself highly hydrophilic (higher hydrophilicity than most polymers used to make membranes, eg PVDF, PP, PES, PS and a long etc., generally more or less hydrophobic and tending to facilitate its contamination by "organic") is highly desirable, since a simple backwash without the use of reagents would mechanically remove the organic materials retained, since they do not they attach so easily to hydrophilic (more or less hydrophilic) surfaces and to the pores of filter membranes.

Indeed, the binding of proteins to highly hydrophilic surfaces is weak, and an agitation that generates a

value

high in the number of Reynolds is enough for its

elimination

of the surface hydrophilic. No So of the

surfaces

hydrophobic than require without doubt the use of

reagents

how the before mentioned.

Even more favorable is the previous phenomenon if a second layer of a polymer is applied to the catecholamine.

highly

hydrophilic, how can to be any polyether

(polyethylene glycol,

polypro pilenglicol, etc.) . The effect

previously

indicated of "difficulty in the fixation of

organic "is further enhanced with this type of polymers bound to catecholamine. The fixation of this second polymer can be carried out as indicated by Messersmith in the annex to the article published in Science (H. Lee et al. Supporting Online Material for Mussel -Inspired Surface Chemistry for Multifunctional Coatings (Science) 318, 426

(2007)).

However, the fact that the binding of proteins, bacteria, fungi or any "organic" is seen to be several orders of magnitude decreased in its ability to bind to a membrane covered in the manner described does not mean that it is non-existent. Over time, a more active removal of organic matter is also required in these cases, which has ended up fixing on the interior (pores) or exterior surface of the membranes, even if they have the most hydrophilic of coatings or the best of repellents of "biofouling" (generic name with which the contamination and silting by organic matter of any type of filtering materials, such as membranes) is applied internationally on catecholamine.

A major problem arises here because most classic laundry products chemically attack catecholamine, so the applied coating disappears in one or more washes. This coating is especially sensitive to oxidants, such as, for example, chlorine, which in its various forms (especially sodium hypochlorite), is used systematically in backwashing of filter membranes due to its ability to remove products that cause the aforementioned and undesirable biofouling, while disinfecting

effectively to them and to the materials that serve them

of

support (modules, fabrics support  of the membranes,

stickers,

housings, structures support, backstage,

containers, etc.).

Membranes, arranged in the form of flat membranes

or hollow fiber membranes, whether reinforced (or supported on a fabric) or integral (not supported), installed in the form of suction filtration systems or in the form of pressure filters, intended to filter clean water with low pollutant load, or to filter highly loaded waters (such as MBRs for the treatment of Urban Wastewater and Industrial Wastewater), they face the same biofouling problem, more or less intensely depending on the characteristics of the water or fluid to be filtered.

The invention presented below focuses on the development of an alternative cleaning treatment for membranes coated with one or more highly hydrophilic polymer films, such as catecholamine and polyether, by using a new bacterial cleaning agent. in substitution of the commonly used chemical products, in order to achieve a cleaning method of these membranes covered with polymeric films that, on the one hand, do not chemically attack said polymeric coating films, avoiding their deterioration, and in turn, being capable of effectively remove all organic matter deposited on (or inside) the membrane during operation.

DESCRIPTION OF THE INVENTION Brief description of the invention

An excellent solution has been found, applicable to any of the systems or arrangements discussed above, which consists of a procedure without alternative chemical reagents for washing, sterilizing and disinfecting membranes coated with at least one

film of at least one hydrophilic polymer, such as a

catecholamine or a polyether, and preferably coated with

a double film, without deterioration or

chemical attack by the cleaning agent towards

5

said coating film (s) or towards the

membrane itself. The cleaning method consists of

use of an agent selected from hot water,

water vapor, superheated water or a mixture of these two

latest on the membrane in question that is

1 O

coated with at least one highly polymeric film

hydrophilic.

Detailed description of the invention

The present invention, as expressed in the statement

of this specification, refers to a method of

fifteen

cleaning and disinfection of membranes coated with at least

a film of at least one hydrophilic polymer,

characterized in that said method comprises injecting a

cleaning agent selected from the compound group

by hot water, steam, superheated water and a

twenty

mixing these last two to the membrane.

The membranes are preferably of the membrane type

semipermeable, and more preferably they are hydrophobic. In a

of the invention, the membranes more particular embodiment

either supported (i.e. they are of the hollow fiber type,

25

made on a support) or integral (not supported)

Also preferably, semi-permeable membranes

hydrophobic are of the type selected from the group

consisting of: reverse osmosis membranes,

nanofiltration, microfiltration (MF) and ultrafiltration

30

(PHEW)

In another particular embodiment, the membranes

coated are supported within a complete module of

membranes, which is in turn fully or partially coated

with the at least one hydrophilic polymer and consisting of all

35

the elements necessary for the proper functioning of

the membranes. In these cases, the coated membranes are presented as bundles or grouped, having one or more filtered water collectors common to all of them, in what is commonly called a membrane cassette,

frame

or package of membranes. The reference to a

covering

total or partial of the module or frame of

membranes

than is washed by the process described I know

it is due to the possibility that the at least one hydrophilic polymeric film covers said module in one of the following ways: that it only covers the membranes contained in the module as stated in the invention; covering all parts of the module in contact with water during the filtration phase, the backwash phase or both phases; and even if the entire membrane containment or support system within the module is covered by said polymeric film.

Particularly in another embodiment, the membranes are supported within a closed pressure filter, or in their absence, a typical container of the so-called "membrane pressure filters" of MF, UF, or any other membrane in which pores are defined as MF or UF, nanofiltration, or reverse osmosis.

The at least one hydrophilic polymer comprised in the at least one coating film is preferably selected from catecholamine, catecholamine derivatives, polyether, polyether derivatives and any combination thereof. Catecholamine is preferably selected from adrenaline, norepinephrine, dopamine, polydopamine, phenylethylamine, and a combination thereof. For its part, the polyether and the derivatives of the polyether are preferably selected from polyethylene glycol, polypropylene glycol, polyetheramine with one, two, three or more amino groups capable of reacting with catecholamine in a highly efficient way, and a combination thereof.

In a preferred embodiment of the invention, the membrane or module is also covered by a second hydrophilic polymeric film comprising, like the first, at least one hydrophilic polymer. More preferably, the hydrophilic polymer comprised in the second film overlying the device in question is selected from catecholamine, a polyether, and a combination thereof. The specifications given for both catecholamine and polyether for the first polymeric film are also met for the second.

In an even more particular embodiment, the first coating film is catecholamine, and the second is polyether.

In another preferred embodiment, the second polymeric film is covalently bonded to the first coating film.

In the preferred case in which the membranes are covered with two polymer films, one of catecholamine and the other of polyether, said membranes have a greater resistance to biological fouling produced in water purification processes, such as wastewater, decreasing the amount of organic matter that is deposited on the membranes.

The temperatures used for the cleaning agent, higher than the optimum growth of the bacteria and microorganisms present in the membranes, inevitably cause the death of the microorganism or sublethal lesions. With a few exceptions, it is perfectly established that the kinetics of bacterial thermodestruction is logarithmic, so the higher the temperature, the greater the destruction of bacteria. Bacteria that grow at high temperatures, such as thermophilic bacteria, develop up to 80 ° C, but from this value almost all microorganisms begin to die. In general we can affirm that almost

any organic pollutant is removed above 85 ° C. Therefore, the injection of the cleaning agent is carried out at a temperature of at least 85 ° C.

The cleaning agent to be used is chosen from hot water, steam, superheated water or mixtures of the latter two.

The hot water must be at an elevated temperature, at least 85 ° C, preferably 90 ° C, and more preferably 95 ° C.

"Superheated water" means water whose temperature is between the boiling point

(100 ° C) and the critical temperature (374 ° C) and that is maintained in the liquid phase by the effect of pressure. The superheated water remains liquid because it is put under pressure when it exceeds the boiling point, or because it is heated in a closed tank with a higher space where the liquid water is equilibrium with the steam at the saturation pressure.

As the water temperature rises above 85 ° C, the hydrogen bonds are broken, changing their properties in a very remarkable way. Thus, as the temperature increases, the water molecules move more freely, with which the viscosity and surface tension of the water decrease and the diffusivity increases. Likewise, water becomes less polar and behaves more like an organic solvent, increasing the solubility of organic matter in it. That is why water vapor, superheated water or mixtures of the latter two become excellent cleaning agents for membranes clogged with organic matter.

In view of the above, the materials that make up the membrane, its support, the module that comprises it and all the accessories and attachments that a filtration system may require in any manufacturer must withstand temperatures of at least 85 ° C.

Preferably, the steam or superheated water is injected at a pressure of between 1 and 3 atm, more preferably being 2 atm, and for a time of between 5 and 30 minutes, more preferably being 10 minutes. In particular, the steam or superheated water is injected at a temperature of 110 ° C and a pressure of 1.4 atm for 10 minutes. Still more preferably, in a particular embodiment, the temperature may be 105 ° C, the pressure 1.2 atm, and the injection time 15 minutes.

In view of the above, the described coated membranes (preferably those of hollow fiber), either with one or two polymeric films, have to resist both the temperatures and the pressures mentioned above. When the resistance of the membrane is mentioned, especially the hollow fiber-covered one, it refers to the thermal and mechanical resistance of the entire membrane as a whole, said membrane being able to further comprise an internal reinforcement and a base polymer film. In a particular embodiment, the membrane may be composed of an internal reinforcement in the form of a hollow fiber, a coating film of a base polymer, a first additional polymeric film of catecholamine, catecholamine derivatives, polyether and / or polyether derivatives, and a second additional polymeric film of catecholamine, catecholamine derivatives, polyether and / or polyether derivatives.

Likewise, all the necessary materials, the adhesives that fix the membranes, the supports of the same, the heads that encapsulate them, the supports of the heads, the screws, the gaskets, the covers, the modules that comprise it and all the accessories and additions that a filtration system may require with any manufacturer must withstand the temperatures and pressures previously specified.

On the other hand, hot water, water vapor, superheated water or a mixture of the latter two must pass through the membranes. In a particular case, said cleaning agent is applied in the direction of filtration from the outside to the inside of the membrane, while in another more preferred embodiment the agent is applied from the inside to the outside of the membranes (counter-current direction, this it is in the opposite direction to the filtration).

In accordance with the description given for the invention, the above objectives of eliminating biofouling and disinfecting the system are met, without the need for any other type of chemical reagent, this washing not sensitively affecting the bonds of the applied hydrophilic polymers. , either catecholamine or polyether type, the polymers of the second film being

reticulated

or fixed acts by a alone link or by various to the

polymer

of the first.

The

cleaning previous is especially effective in

membranes

of fiber hollow, in where the Water hot, the

Water vapor, superheated water, or a mixture of the latter two passes through the membranes in countercurrent as occurs in conventional MF or UF membrane washing. For example, it is even more effective in module designs such as those registered in the Spanish application for Utility Model No. U200930468, since it guarantees an excellent distribution of the cleaning fluid (either hot water, steam, superheated water or a mixture of these two Especially efficient is the application of this mode of washing and disinfection in closed pressure filters, where the filter itself acts as an "auto-key", reducing the energy consumption necessary to wash the membranes.

(closed filter systems).

Within this type of closed filters or working under pressure during the filtration phase, a filter arrangement and filter elements are more efficient

such as that contained in the Spanish patent application no P200930470, as it has a minimum of dead spaces and an excellent distribution of hot water, steam or water

overheated

or mix of both of them, in its road since the

inside

the membranes outward from these.

Other

of the advantage than presents this method of

washed,

completely unpublished in the technology of the

semipermeable membranes, MF or UF, is the need not to use any chemical additive, oxidant, etc., which generates more or less contaminating residues that must be post-treated, which converts the washing process described here in a more ecological and non-aggressive process with the environment.

DESCRIPTION OF THE FIGURES Figure 1: Evolution of the permeate flow as a function of the exposure time to the cleaning agent (water vapor). Figure 1 represents the flow rate permeated by different types of membranes described and analyzed in the Embodiment Example of the invention, both uncoated and coated as defined in the present invention: coated with catecholamine, coated with catecholamine (the film) + polyether -monoamine (2nd film) and coated with catecholamine (1st film) + polyether-diamine (2nd film), depending on the number of days exposed to water vapor. Specifically, the following cases have been prepared: uncoated membranes (line with a diamond-shaped marker) and catecholamine-coated membranes (line with a square-shaped marker); catecholamine (the film) + polyether diamine 1000 (2nd film) (line with star-shaped marker); catecholamine (1st film)

+ polyether-diamine 2000 (2nd film) (line with circle marker); catecholamine (1st film) + polyether-monoamine 1000 (2nd film) (line with triangle marker); and catecholamine (the film) + polyether-

monoamine 2000 (2nd film) (line with cross marker).

Figure 2: Evolution of the coating film as a function of the time of exposure to sodium hypochlorite. Figure 2 illustrates the decrease in the catecholamine and polyether amine coating thickness used in the membranes of the Embodiment Example when subjecting these samples to a cleaning with a 0.5% solution of sodium hypochlorite

(NaClO) at pH 9.5 and at room temperature. The cases shown are: catecholamine (the film) + polyether-monoamine 1000 (2nd film) (line with square-shaped marker); and catecholamine (1st film) + polyether-monoamine 2000 (2nd film) (line with triangle marker); catecholamine (1st film) + polyether-diamine 1000 (2nd film) (line with blade-shaped marker); catecholamine (the film) + polyether diamine 2000 (2nd film) (line with star-shaped marker) Figure 3: Evolution of the permeate flow rate as a function of time of exposure to bacterial fouling. Figure 3 shows the evolution of the permeate flow over the bacterial fouling time of the membranes analyzed in the Embodiment Example. The cases shown are: uncoated membranes (line with a diamond-shaped marker); membranes coated with catecholamine (the film) + polyether-monoamine 1000 (2nd film) (line with square marker); catecholamine (the film) + polyether-monoamine 2000 (2nd film) (line with triangle marker); catecholamine (1st film) + polyether-diamine 1000 (2nd film) (line with blade-shaped marker); and

catecholamine

(the movie) + polyether diamine 2000 (2nd

movie)

(line with marker in shape of star)

EXAMPLES

OF REALIZATION

TO

continuation I know they detail, to mode of example and with

non-limiting nature of the invention but only illustrative, a series of tests carried out and the

results obtained from the application of the cleaning and disinfection method for different hollow fiber membranes, both uncoated (reference) and coated with one or two hydrophilic polymer films: catecholamine, catecholamine (the film) + polyether-monoamine (2a film) and catecholamine (1st film) + polyether diamine

(2nd film).

The hollow fiber membranes used for their subsequent coating with catecholamine and / or with

Polyetheramine are composed of a hollow fiber braided interior reinforcement made of materials resistant to pressure and temperature increases generated when applying the cleaning agent.

In particular, the reinforcement used is made of a polymer with high thermal and mechanical resistance, such as polyamide or polyester. A film of a base polymer is deposited on said reinforcement, which properly acts as a separation membrane for particles and organic matter. In the particular case of this example, this coating film is made of PVDF polymer, offering a high thermal and mechanical resistance against any of the previously described cleaning agents.

Once the hollow fiber membranes were covered with polymeric films of both catecholamine and catecholamine plus polyetheramine, they were subjected to a cleaning, sterilization and disinfection treatment according to the present invention, using steam, in order to simulate the real cleaning conditions to which these coated membranes could be subjected throughout their useful life and thus be able to check the resistance of these polymeric coatings to said cleaning agent.

For this, hollow fiber membranes coated with

catecholamine and catecholamine plus polyetheramine were glued

in small tubes to prepare a series of modules

test. The membrane modules were connected to a

5

collector-system in which steam was introduced by an extreme

of water (although the same method and device can

also be used with hot water, superheated water or

a mixture of steam and superheated water as

agent), which was introduced through the interior gap of the

10

membranes, flowing from the inside to the outside of

the same (in countercurrent sense) In the case

Particular of the present example, steam of

water at a temperature of 105 ° C and a pressure of 1.2 atm.

After 24 h, the membranes subjected to water vapor

fifteen

in the aforementioned conditions, they were withdrawn and

immersed in deionized water at room temperature

for 10 min to temper them. Then they were measured

both the permeate flow and the bubble point of the

membranes subjected to water vapor.

2 O

Once the membranes were characterized, they were dried with

nitrogen for 5 min and reintroduced into the

reactor to re-steam them for

another 24 h. In this way, the samples were submitted

to the cleaning treatment with steam for 7 days

25

followed, time calculated to simulate the accumulation of

all steam cleaning to which the

membrane throughout its useful life.

Figure 1 shows that in all cases the

permeate flow rate increases slightly over time

30

exposure to water vapor, although the initial flow varies

from one case to another. Specifically, the order of flows

initials is as follows: uncoated> catecholamine>

catecholamine + polyether diamine 1000> catecholamine +

polyether diamine 2000> catecholamine + polyether monoamine

35

1000> catecholamine + polyether-monoamine 2000. This order of

flows is related to the number of movies

coating, as more films are added

of coating to the membrane the flow tends to decrease

due to the increased pressure drop of the membrane. In

5

cases of catecholamine + polyether coating,

notes that polyether diamine has a higher flow rate than

polyether-monoamine, since polyether diamine has

double amino group (-NH2) and that this group confers a

high hydrophilicity to the polymer due to the creation of

10

hydrogen bridges between the group nitrogen atom

amino and the hydrogen atom of the water molecule. In

Regarding molecular weight, it is observed that the membranes

coated with lower molecular weight polyetheramines

have a higher permeate flow than the corresponding

fifteen

higher molecular weight, because increasing length

of the polyetheramine chain generates a greater blockage of

superficial pores.

In Figure 2, it is observed in all cases that the

polymer coating ends up disappearing after

2 O

6 -8 h of cleaning with sodium hypochlorite. Hypochlorite

sodium, due to its high oxidizing power, ends up oxidizing

completely to the coatings films of

catecholamine and polyetheramine, destroying them in no time

weather. These results confirm the suitability of the

25

steam cleaning, cleaning with

sodium hypochlorite too aggressive for these membranes

coated.

The evolution of the flow is represented in Figure 3

permeated through bacterial fouling time

30

of the membranes. The uncoated membrane, although it starts with

an initial flow rate greater than any coated membrane,

suffers a noticeable and progressive decrease in flow

permeated with exposure time to soiling

bacterial, without any tendency towards a

35

final stabilization of the flow. However, with the

catecholamine and polyetheramine coating the permeate flow in all cases remains practically unchanged with time of fouling. This fact is due to the fact that the catecholamine and polyetheramine coating achieves a significant reduction in the adsorption of proteins and bacteria on its surface, and that it also remains constant throughout the fouling time.

For all these reasons, it can be concluded that the coating of the membranes with catecholamine plus polyetheramine is a very effective method in reducing the adsorption of organic matter on the surface of the membranes compared to the uncoated membrane, reducing the number of cleanings necessary. On the other hand, cleaning these membranes with hot water, steam, superheated water or mixtures of these last two agents not only does not create any negative effect on them, but also has the advantage of slightly increasing the flow rate permeated by the themselves. Therefore, treatment with hot water, steam, superheated water or mixtures of the latter two is a very suitable method for cleaning the membranes, preferably hollow fiber coated with hydrophilic polymers such as catecholamine and / or polyetheramine, since that in addition to eliminating the organic matter retained in the membranes, not only does it not produce any type of thermal or mechanical degradation in the different catecholamine and / or polyether polymer coatings, but it also does not cause it in the internal reinforcement of polyester or polyamide, nor in the PVDF base polymer film, or in any component of the module and, in general, in any accessory of the whole of the present filtration system.

Claims (23)

l. Method for cleaning, sterilizing and disinfecting membranes coated with at least one film of at least one hydrophilic polymer, characterized in that said method comprises injecting into the membrane a cleaning agent selected from hot water, steam, superheated water or a mixture of these last two.

2.

Method according to claim 1, characterized in that the hot water is injected at a temperature of at least 85 ° C.

3.

Method according to claim 1, characterized in that the hot water is injected at a temperature of at least 90 ° C.

Four.

Method according to claim 1, characterized in that the hot water is injected at a temperature of at least 95 ° C.

5.

Method according to claim 1, characterized in that the steam, the superheated water or the mixture of these last two agents is injected at a temperature of at least 100 ° C.

6.

Method according to claim 1, characterized in that the steam, the superheated water or the mixture of these last two agents is injected at a temperature of at least 105 ° C.

7.

Method according to any one of claims 1, 5 or 6, characterized in that water vapor, superheated water or the mixture of these last two agents is injected at a pressure of between 1 and 3 atm during a

time between 5 and 30 minutes.

8.

Method according to any one of claims 1, 5, 6 or 7, characterized in that the steam, the superheated water or the mixture thereof is injected at a pressure of between 1 and 2 atm for a time between 10 and 20 minutes.

9.

Method according to any one of the preceding claims, characterized in that the cleaning agent selected from hot water, steam, superheated water or a mixture of the latter two passes through the membrane in a countercurrent direction from the inside to the outside of the membrane .

10.

Method according to any one of the preceding claims, characterized in that the membranes are hollow fiber hydrophobic semipermeable selected from the group consisting of reverse osmosis membranes, nanofiltration membranes, ultrafiltration membranes and microfiltration membranes.

eleven.

Method according to any one of the preceding claims, characterized in that the membranes are supported within a complete module of membranes consisting of all the elements necessary for their correct operation.

12.

Method according to claim 11, characterized in that the complete module of membranes comprises, in addition to the membranes: adhesives that fix said membranes, supports for them, heads that encapsulate them, supports for the heads, screws, gaskets, covers, and other accessories and accessories that a filtration system needs, in such a way that all these materials resist and do not degrade to

the temperatures and pressures used to inject the cleaning agent.

13.

Method according to any one of claims 11 or 12, characterized in that the membrane module is totally or partially coated with the at least one hydrophilic polymer in one of the ways selected from: that only the membranes contained in the module are coated; that all parts of the module in contact with water are covered during the filtration phase, the backwash phase or both phases; and that the entire system of containment or supported of the membranes within the module is covered.

14.

Method according to any one of the preceding claims, characterized in that the at least one hydrophilic polymer is selected from catecholamine, catecholamine derivatives, polyether, polyether derivatives and a combination thereof.

fifteen.

Method according to claim 14, characterized in that catecholamine and derivatives thereof are

16.

Method according to one of claims 14 or 15, characterized in that the polyether and the derivatives of the polyether are selected from polyethylene glycol, polypropylene glycol, polyetheramine with one, two, three or more amino groups, and a combination thereof.

17.

Method according to any one of the preceding claims, characterized in that the first film of

selected

between adrenalin, norepinephrine, dopamine,

polydopamine,

phenylethylamine and a combination of the

themselves.

Membrane polymer is also coated with a second film of at least one hydrophilic polymer.

18.

Method according to claim 17, characterized in that the at least one hydrophilic polymer of the second coating film is selected from catecholamine, catecholamine derivatives, polyether, polyether derivatives and a combination thereof.

19.

Method according to any one of claims 17 or 18, characterized in that the membranes are covered by a first catecholamine coating film and a second polyether coating film.

twenty.

Method according to any one of claims 17 to 19, characterized in that the second polymeric film is covalently attached to the first coating film.

twenty-one.

Method according to any one of the preceding claims, characterized in that the membranes further comprise an internal reinforcement and a base polymer film.

22.

Method according to any one of the preceding claims, characterized in that the internal reinforcement, the base polymer film, the first hydrophilic polymer film and the second hydrophilic polymer film are totally resistant to the pressures and temperatures described in previous claims.

2. 3.

Method according to any one of the preceding claims, characterized in that the membranes are contained inside a pressure filter.