FR3107657A1 - A method and system for the recovery of polyphenols from solid waste or from solid waste and industrial liquid waste from the food and beverage sector - Google Patents

Abstract

"A process and system for the recovery of polyphenols from solid waste or industrial solid waste and liquid waste from the food and beverage industry" The process is characterized by comprising the steps of:a) subjecting solid waste, in batches, to an extraction of polyphenols by adding a solvent and to the action of ultrasound/microwaves to obtain treated volumes of solution; b) introducing and retaining in an intermediate tank one or more volumes of solution treated;c) impelling all or part of the contents of the intermediate tank as feed for a continuous process which includes the serial operations of microfiltration, ultrafiltration and reverse osmosis,d) reusing the permeate from the reverse osmosis as a solvent in operation a) or as a contribution to the intermediate tank to increase the sedimentability of the solids contained in the intermediate tank, protecting the membranes from their r clogging and fouling. Figure for abstract: Fig. 2

Description

A method and system for the recovery of polyphenols from solid waste or from solid waste and industrial liquid waste from the food and beverage sector

Technical sector of the invention

The invention relates to a process for the recovery of polyphenols present in solid waste and liquid waste (effluents included) from the food and beverage industries, such as those dedicated to the production of olive oil and wine.

The invention also relates to a system for performing such recovery of polyphenols present in said solid waste and industrial liquid waste mentioned.

History of the invention

Polyphenols, a group of phytochemicals found in fruits, vegetables and cereals, are compounds that are highly valued today for the antioxidant effect they produce in our body, and are therefore of great interest to the cosmetic industries. , pharmaceutical and food. Polyphenols are not only found in the consumable part of fruits and vegetables, but also in their parts that are discarded, such as the skins, pulps and seeds. The consumption of polyphenols has increased in recent years by more than 7%, so there is a need to expand the sources of polyphenols and develop adequate processes for their extraction.

In the wine industry, it is known that among the phenolic compounds, anthocyanins and the pigments derived from them, produced by co-pigmentation or condensation processes, are the compounds that most influence the coloring of red wines and rosé giving rise to orange, red, purplish or blue colorings. The transfer of the phenolic compounds responsible for the color of the skin to the liquid phase (must) after a crushing process is closely linked to the raw material and the winemaking techniques used and has a decisive influence on the variety, the degree of maturity and size of the grape, as explained in Spanish patent ES2478190-B2. Said patent refers to a process, module and equipment for the extraction of compounds from grapes by ultrasound in winemaking processes, and in particular the transfer of the phenolic compounds responsible for the color of the skin to the liquid part. (must) after crushing the grapes, using for this a process and equipment based on the generation of ultrasound. The phenomenon of cavitation is generated by the use of ultrasound, which allows the breakage of skin cells and makes available to the liquid medium the phenolic compounds responsible for the color so that they integrate into said reinforcing liquid medium. the color of the wine.

Another application of polyphenols, this time in the olive oil industrial sector, is that envisaged in patent application document EP2994225-A1, which describes a reactor for increasing the quantity of polyphenols contained and / or the stability of the turbidity of extra virgin olive oil over time. The reactor comprises a cavity adapted to receive a product consisting of olive oil or olive paste from which extra virgin olive oil is obtained, and at least one source of ultrasound adapted to vibrate the body of said cavity.

On the other hand, some wastewater generated in industrial processes in the food sector has high pollutant loads and the application of conventional treatments is not sufficient. In this context, we find, for example, wastewater from the production of table olives and wastewater from oil mills, the latter from the pressing of olives to produce olive oil in a proportion close to 50% of the weight of the pressed olives. This wastewater is distinguished by its high content of highly polluting organic compounds (polyphenols), which generates an environmental problem with regard to their disposal and treatment, since the treatments in conventional wastewater treatment plants are not sufficient to solve this problem. problem.

In order not to waste the polyphenols present in agro-industrial waste from vegetable, solid and / or liquid sources, several techniques and processes have been studied and developed.

To this end, the AINIA technological center has developed an industrial plant (known as ALTEX) for the extraction of _{supercritical CO 2} to recover polyphenols, with an extraction capacity of 4000 liters. Even if a recovery of polyphenols from industrial rebus is carried out effectively, it has certain limitations such as the high energy consumption or the high initial investment (CAPEX) that it requires, which can limit its viability.

Spanish patent ES2319032-B1 describes a process for extracting polyphenols from grape pomace from distillation which relies on the collection of residual pomace from the distillation process carried out by steam stripping and direct heat. Extraction of the polyphenols from said marc is carried out by using a hydroalcoholic mixture (ethanol / acidified water at pH 1, 50:50), at a temperature of 40 to 55 ° C and for a period of 3 to 4 hours. After the extraction process, said stream is cooled to 25 ° C and is purified by filtration to 100 microns and subsequent centrifugation to remove the precipitated solids. The liquid obtained is stabilized by adding 0.20 to 0.60 g of sodium alginate for each liter of polyphenolic extract and is concentrated to 50%, recovering a 70:30 ethanol / water condensate, for his reintroduction to the process.

This process relies on a conventional solid-liquid extraction, so an extraction process that can improve the recovery efficiency of polyphenols, reduce extraction time and reduce solvent requirements would be desirable.

Spanish patent ES2455999-T3 describes a process for obtaining a natural concentrate rich in hydroxytyrosol from waste and by-products of the olive tree, which consists of the following steps: a) treating the solid waste and semi -solids from the olive tree by extraction with water or with hydroalcoholic mixtures, b) either supply the extract which contains hydroxytyrosol and other bioactive compounds from the olive tree directly to a nanofiltration unit with a cut-off molecular weight of less than 300Da, or mix the extract obtained in step a) with the vegetable water from the crushed olives and centrifuge in the object to remove particles and other suspended solids, and provide the supernatant obtained from the centrifuge at said nanofiltration unit, wherein said hydroxytyrosol and other low molecular weight bioactive compounds are recovered in a permeate stream from said nanofiltration unit, and c) supplying the fluid x of permeate from said nanofiltration unit to the supply compartment of a reverse osmosis unit, wherein said hydroxytyrosol and other bioactive compounds are retained and concentrated in a retentate stream. As a disadvantage, it should be mentioned that the conventional extraction involves a high extraction time and high solvent consumption, which increases the operational cost and has a lower extraction efficiency in comparison with other extraction solutions. more advanced polyphenols. The application of a conventional extraction makes coupling with a membrane treatment difficult because the latter works in continuous mode and the conventional extraction involves a long extraction time.

As regards the wastewater from oil mills and their content of compounds of interest to the cosmetic, pharmaceutical, dietetic and food industry, patent ES2335418-T3 discloses a process for the recovery of tyrosol and hydroxytyrosol from wastewater of oil mill, as well as a catalytic oxidation method to convert tyrosol to hydroxytyrosol. The process in question consists of a step a) of coarse filtration or pre-filtration, microfiltration, ultrafiltration, nanofiltration and reverse osmosis of water, preferably at neutral or alkaline pH, a step b) of chromatographic separation of tyrosol, hydroxytyrosol and other phenolic compounds from the concentrate or from the reverse osmosis reject, a step c) of oxidation of the tyrosol thus obtained to give hydroxytyrosol in the presence of methylrenium trioxide and of hydrogen peroxide in a protic solvent, and a step d) of concentrating and spraying the high molecular weight portion with the recovery of water and high value added compounds.

The main limitation of this process is that it only offers treatment for liquid waste from water of plant origin, while in Spain 75% of olive oil extraction is carried out in two-phase extractions that generate solid waste. Also, it should be considered that in addition to tyrosol and hydroxytyrosol, the wastewater may contain other polyphenols which are not retained in their entirety by the membranes of the operations of step a). Another aspect to take into account is that after the process it is necessary to remove the catalysts, especially methylrenium trioxide, which is a strong irritant.

ES2595939-B1 relates to a process for recycling and reusing liquid effluents from olive oil extraction. The process aims to reduce the consumption of drinking water, to reuse wastewater and also to prevent certain compounds, such as phenolics, from being wasted in wastewater. The process consists of passing the waste water from washing or planting through a filtration system which includes, at a minimum, a filter placed downstream of the separation equipment; to introduce the reused water into a compensation tank with drinking water, placed upstream of the separation equipment for the olive oil extraction process; and reintroducing the water mixture into the phase separation unit.

So what is actually done is using the recycled water, which still contains polyphenols, for the three-phase extraction of olive oil. The separation is relatively simple because, in reality, we do not do an isolated recovery of the polyphenols but reintroduce the polyphenols present as part of the recycled water in the olive oil extraction process.

Spanish patent ES2641069-T3 discloses a process for the extraction and concentration of polyphenolic compounds contained in vegetation water and / or the pomace obtained from the treatment of olives which comprises a step 1) of collecting the liquid consisting of water from vegetation and / or marc after the olive grinding process; a step 2) of chemical, physical and enzymatic pretreatment; a step 3) of tangential filtration at a temperature in the range of 45 to 50 ° C, preferably of ceramic microfiltration, thus obtaining a fraction of concentrate and a fraction of permeate; and a step 4) of vacuum evaporation of the permeate phase obtained in step 3). The pretreatment 2) for its part comprises a step a) of acidification to a pH of between 2.5 and 4; a step b) of enzymatic treatment by adding a reserve of cellulolytic and pectolytic enzymes. During said treatment the liquid is maintained under hydraulic agitation by operating a process for the recirculation of the same liquid eccentrically with respect to the wall of the reactor, in which said agitation is maintained for a period of 2 to 6 hours, preferably for approximately 4 hours. at a temperature in the range of 30 and 50 ° C when working with vegetation water, and said hydraulic agitation is maintained for 12 to 24 hours at a temperature in the range of 50 to 80 ° C when the we work with marc. Pretreatment 2) also comprises a step c) of removing the solid or semi-solid waste which is collected on the surface at the end of said step b) where said waste has a density of between 0.70 and 0.85 g / cm ³ , wherein said removal takes place by pumping and sending the liquid mass collected at the bottom of the pre-treatment tank to the subsequent filtration section and said plug constitutes 2 to 7% by weight based on the total mass of the vegetation water and contains approximately 20% of the solids present in the initial vegetation water.

In this process, the permeate from the microfiltration is directly evaporated after an enzymatic pretreatment, so that the obtained extract of polyphenols will contain polysaccharides and other impurities since it cannot be separated only by a microfiltration membrane. In addition, a high operational cost associated with the evaporative energy (pressure and heat) is expected, as the evaporation applies to all of the microfiltration permeate. In addition, enzymatic hydrolysis does not reduce operating times compared to conventional extraction. Another drawback is that polyphenols have different polarities, so extraction with only water makes it difficult to extract nonpolar polyphenols.

As for the wine sector, patent ES2319032-B1 describes a process for extracting polyphenols from grape pomace obtained from distillation which comprises the following steps: a) extraction of the pomace by continuous diffusion in counter-current using as extractor a 50:50 solution of ethanol: water acidified to pH 1, at a temperature of 40 to 55 ° C and for a period of 3 to 4 hours, the pomace: extractor extraction ratio being in the range 1: 2- 3.5, an extraction marc and an extraction juice being obtained; b) pressing of the extraction grounds resulting from step a) at a pressure between 2 and 10 kg / cm ² , a pressing grounds and a pressing juice being obtained; c) mixing the extraction juice obtained in step a) and the pressing juice obtained in step b), followed by cooling the resulting mixture to 25 ° C, purification thereof by filtration at 100 microns and centrifugation, a clarified juice and a solid waste being obtained; d) stabilization of the clarified juice obtained in step c) by adding sodium alginate at a concentration of 0.2 to 0.6 g / l of clarified juice; and e) concentration of the stabilized juice obtained in step d) in a vacuum evaporator at 60-70 ° C until the volume of stabilized juice is reduced by approximately 50%, so as to obtain a polyphenolic extract with antioxidant power in a range between 150,000 and 250,000 mg of gallic acid / kg of dry marc.

A disadvantage of this process is that polysaccharides, sugars and other impurities cannot be separated by pre-filtration and evaporation.

It appeared above that one of the main problems of solid-liquid extraction is its high consumption of solvent and / or its regeneration (evaporation), which has an impact on an increase of the operational cost and reduces the durability. of the process. The development of new extraction techniques without the need for organic solvents (extraction under pressure, supercritical extraction with CO ₂ ) was also presented. However, these new techniques increase energy consumption, without reducing the extraction time, and can reduce the recovery efficiency of polyphenols due to the limited extraction of hydrophilic polyphenols.

For these reasons, the use of other advanced extractions is envisioned as an alternative, such as for example by ultrasound or microwave to improve the solid-liquid extraction by a mixture of organic solvents and water, which can be effective in recovery of polyphenols from waste generated in the food and beverage industries. It should be mentioned that although this alternative would greatly reduce the required amount of solvent, there is the problem of the high energy consumption for the evaporation required to regenerate the organic solvent used so that another objective of the present The invention will consist in solving the problem of reusing the solvent used in this type of advanced extractions.

Another equally important objective of the present invention is to provide a process and a system allowing the recovery of the polyphenols present both if solid waste is available as well as liquid waste, effluents included, from such industries.

Another priority objective of the present invention is to be able to recover the polyphenols present in said waste with a high degree of purity, namely, that they are separated from other compounds such as colloidal matter, proteins or carbohydrates.

Explanation of the invention

With the aim of providing a solution to the problems raised above, a process is proposed for the recovery of polyphenols from solid waste or from solid waste and industrial liquid waste from the food and beverage sector, such as for example of the olive oil and wine industry. It is understood that liquid wastes also include effluents, since these liquids come from an industrial plant.

In essence, the method of the invention is characterized in that it comprises the operations of:
a) subjecting the solid waste, in batches, to a polyphenol extraction operation by adding a solvent and to the action of ultrasound or microwaves to obtain treated volumes of solution;
b) introduce and retain in an intermediate reservoir one or more volumes of treated solution
c) propel all or part of the content retained in the intermediate tank as feed for a continuous process which includes the serial operations of membrane microfiltration, ultrafiltration of the membrane microfiltration permeate and membrane reverse osmosis of the permeate of the ultrafiltration,
the method further comprising a reuse of the permeate of the reverse osmosis as a solvent in step a) or as a supply to the intermediate tank to increase the sedimentability of the solids present in the contents retained in the intermediate tank and to protect the membranes by avoiding that 'they are not obstructed and reduce the fouling thereof.

In the process which is the subject of the invention, in the event that industrial liquid waste from the food and beverage sector is available, this liquid waste is introduced and retained in the intermediate tank, or they are introduced downstream of the intermediate tank and propelled as feed of the continuous process of membrane microfiltration, ultrafiltration of membrane microfiltration permeate and membrane reverse osmosis of ultrafiltration permeate.

In this way, the process which is the subject of the invention proposes an integrated solution for the recovery of polyphenols which includes an advanced extraction process, in particular by ultrasound or by microwave, to recover the polyphenols from solid industrial waste, coupled to a membrane treatment train to purify and concentrate the polyphenols present in solid waste and in industrial liquid waste.

Advanced extraction, referred to here as ultrasonic or microwave assisted extraction, reduces extraction time and solvent requirements compared to other alternatives on the market, such as direct membrane filtration or extraction conventional, maximizing at the same time the yield of the extraction. This advanced extraction is focused on the extraction of polyphenols present in industrial solid waste, preferably using a combination of water and ethanol (although other solvents can be applied) to maximize the recovery of polyphenols, however. that is the hydrophobicity of the compounds of industrial solid waste.

On the other hand, although in the state of the art there are several solutions based on a treatment train to recover the waste of olive oil, these mainly aim to recover the water from the vegetation. (liquid waste) and do not correspond to the same membrane treatment train of the process of the invention. In the process of the invention, a reverse osmosis operation is applied as a result of the ultrafiltration operation, and not nanofiltration, in order to increase the recovery of polyphenols. This is due to the fact that the inventors observed that the MWCO (molecular weight limit in English, also called molecular weight threshold) of certain polyphenols, for example the MWCO of those of olive oil, is similar to the MWCO of the size of the particles of the nanofiltration membranes, so that if we had a nanofiltration membrane, there would be polyphenols which would remain in the retentate but others would pass to the permeate, limiting the percentage of polyphenol recovery . Another feature to highlight is the membrane microfiltration which is carried out before the membrane ultrafiltration, to minimize the fouling of the ultrafiltration membrane and increase the life of the membranes.

It should be noted that the process object of the invention is indicated for the treatment of both liquid material and solid material, maximizing the recovery of polyphenols in a single system in which the process is carried out. The integration of a batch process such as the advanced ultrasonic or microwave extraction process, which is carried out in batches, with a continuous process as is the case with purification and membrane concentration treatment, is solves by the accumulation of the volumes of solution treated due to the fact that they have been subjected to ultrasound or to microwaves in the intermediate tank, which makes it possible to have the sufficient quantity available to ensure the continuous supply to the operations in series carried out on such membranes. In this way, the process defines that the intermediate tank is maintained with a certain quantity of liquid throughout the duration of the cycle carried out for the recovery of polyphenols.

The combination of microfiltration, ultrafiltration and reverse osmosis makes it possible to obtain an extract rich in polyphenols from the retentate of the reverse osmosis and to reuse the permeate of the reverse osmosis, which contains the organic solvent and is free of impurities, as a solvent for the extraction step a), without requiring external evaporation steps for the recovery of the solvent. In addition, the application of advanced extraction (ultrasonic or microwave extraction) reduces the extraction time, thus favoring the integration of said extraction with the membrane train, since it is possible to accumulate in a short period of time the sufficient quantity of volumes of solution treated (second by-product) to ensure continuous smooth operation of the series operations carried out on the membranes.

In addition to the above, the process which is the subject of the invention envisages the reuse of the reverse osmosis permeate as a solvent in operation a), which makes it a more durable alternative and contributes to the reduction of economic costs due to the fact that it requires less solvent to be supplied externally to perform the ultrasonic or microwave extraction. The initial solvent that is added at the start of the process to industrial solid waste for said extraction is ethanol (or its mixture with water), an organic solvent whose cost is considerably high. This ethanol (or its mixture with water) is usually contained in a supply tank with an outlet to the chamber where the extraction is performed by ultrasound or microwave. With the reuse of the reverse osmosis permeate as a solvent, a mixture of ethanol and water will act as the solvent in subsequent extractions, thereby reducing the initial ethanol input from the supply tank.

Unlike the other options for recovering the initial solvent (preferably ethanol) as an isolated component, which would involve a long and expensive step of separating the ethanol by evaporation techniques, the process which is the subject of the invention inventively solves the problem of the cost and the supply of the initial solvent (ethanol), configuring the various operations so that in the end the permeate of the reverse osmosis constitutes in itself a suitable solvent for the extraction of polyphenols by ultrasound or microwave, this solvent being, particularly and preferably a mixture of ethanol and water which can be directly added as solvent for said extraction, thus reducing the need to provide a new initial solvent (ethanol). In this way, in the process of the invention, the solvent is recovered in the own process, therefore without it being necessary to have additional external processes such as evaporation because the recovery of the solvent is already integrated. .

In the choice of membranes, the fact that the size of the ethanol molecule is larger than that of water was taken into account, to allow ethanol and not just water, as happens in d other groups of membranes of the state of the art, to cross all the membranes arriving at the permeate of the reverse osmosis. If instead of ethanol, the use of another initial solvent similar to ethanol, with similar characteristics or behavior, is considered, its molecule size will be taken into account in the same way for the choice of membranes. .

In the process of the invention, it has been provided that the volumes of solution treated in the ultrasonic or microwave extraction are subjected to a settling process before the microfiltration operation of the continuous process, to reduce the solids content present at the entrance to the membrane train. This settling can occur either in the extraction installation where the polyphenol extraction operation is carried out, or before they are introduced into the intermediate tank due to the fact that they are subjected to a centrifugation operation for reduce the solids content prior to their introduction, or in the intermediate tank because this tank is formed by a settling tank.

In connection with the above, another aspect to be taken into account is that the method which is the subject of the invention solves one of the problems which can be generated when an extraction is applied jointly with a membrane train, particularly that of the possible presence of solids in the flow coming from the extraction at the inlet of the membranes, which can give rise to a high fouling of the membranes, making their operability difficult because they are blocked by said solids (closing some of the pores of the membranes) . Depending on the specific characteristics of the solid and liquid industrial wastes available at any time, the expected sedimentation or settling of the solid components present may not be sufficient to ensure that the flow to the membranes has a solid content compatible with proper operation. of the latter, and for this reason, in these circumstances, the process which is the subject of the invention envisages the reuse of the permeate from the reverse osmosis as a contribution to the intermediate tank to increase the sedimentability of the solids present in the contents of the intermediate tank and to protect the membranes. , helping to extend their useful life.

According to another characteristic of the process for the recovery of polyphenols which is the subject of the invention, the reuse of the permeate from the reverse osmosis as a solvent in operation a) or as a supply to the intermediate tank is the result of an operation to compare the transmembrane pressure value of the microfiltration process at a membrane protection threshold value, the resulting reuse as input to the intermediate reservoir when such a transmembrane pressure value is equal to or greater than such a threshold value, and as a solvent in step a) when it is lower.

The membrane protection threshold value can be between 5 and 1000kPa, although it is preferably between 50 and 300kPa, although a more restrictive value can also be considered, such as a chosen value and between 100 and 150kPa. Thus, the transmembrane pressure in the microfiltration operation is monitored and in the event that it reaches or exceeds a defined threshold value, the reverse osmosis permeate is sent to the intermediate tank. In all cases, the threshold value which is defined ultimately depends on the type of membrane and the manufacturer's recommendations.

In this way, in the method which is the subject of the invention, the transmembrane pressure of the second by-product of operation c) is measured, at the inlet of the microfiltration system, and if it is high (equal to or greater than the preset threshold value), the reverse osmosis permeate is diverted to the intermediate tank to avoid damaging the membranes. Transmembrane pressure measurement was chosen because it is an easier value to measure and because it allows for better process monitoring than that offered by solid content measurement. The supply of the permeate of the reverse osmosis to the intermediate tank reduces the solids content of the supernatant and therefore, the flow of said supernatant (second by-product) which will be subjected to the microfiltration operation will not present a risk for the integrity of membranes. This function is ad hoc and only when necessary, so that in the rest of the cases, the reuse of the reverse osmosis permeate will serve as the solvent for operation a). In this way, a good coupling is achieved between the extraction operation a) and the continuous operation carried out in the membrane train, making it possible to avoid losses of solvent and to damage the membranes, providing a solution to the problem. technique arising from the conjunction of the process of extraction from solid waste with the serial process of microfiltration, ultrafiltration and reverse osmosis which does not receive only liquid waste, but a mixture of these with the solutions processed in operation a) ultrasonic or microwave extraction. It is also a solution for cases where the liquid waste to be treated, per se, has a high solids content.

It should be mentioned that in the event that a high transmembrane pressure which can damage the ultrafiltration membrane or the reverse osmosis membrane is detected (from a value defined as "high"), the possibility of diverting the permeate from reverse osmosis to one or more of the reservoirs prior to the ultrafiltration or reverse osmosis membranes is envisaged. These earlier reservoirs may be a reservoir provided between the microfiltration membrane and the ultrafiltration membrane, as well as a reservoir optionally provided between the ultrafiltration membrane and the reverse osmosis membrane.

The polyphenol recovery process of the invention provides in situ solvent regeneration, which reduces energy costs compared to conventional ex situ regeneration methodologies, such as evaporation. This reduction is estimated at 20-30kw-h / tonne of waste, which represents up to 90% of the energy consumption in the regeneration of solvents.

In the continuous process fed by the second by-product (treated solution volumes accumulated in the intermediate tank), which can be for example the supernatant of the intermediate tank, in the first place, the flow of the second by-product is subjected to a microfiltration step, to eliminate the presence of solids, mainly of colloidal material which is retained, and to minimize fouling ("fouling" in English) and obstruction ("clogging" in English) of the membranes of the following steps. The permeate from the microfiltration is treated in an ultrafiltration step to purify and concentrate the stream rich in polyphenols. In the case of the ultrafiltration membrane, the pore size of the membrane is between 5 and 10kDa, necessary to purify the flow of polyphenols and reduce the presence of proteins and carbohydrates. The ultrafiltration retentate, after a short evaporation, can be used as animal feed. On the other hand, the permeate from the ultrafiltration is finally subjected to a reverse osmosis process to maximize recovery and concentrate the flow of polyphenols. The polyphenol-rich stream retained in reverse osmosis can be used in own facilities where the polyphenol recovery process of the invention is carried out to produce products enriched in antioxidants or to be sold elsewhere, outside the facilities. Reverse osmosis makes it possible to obtain a permeate stream of high purity, which, as explained above, can be directly recirculated to the extraction operation a) in the object of recovering and reusing the permeate as solvent. For this purpose, the particle size of the reverse osmosis membrane is expected to be between 50 and 120Da, which is necessary to achieve good separation of the polyphenol extract from the solvent stream.

Preferably, it is expected that the membranes are hydrophobic, to avoid the absorption into the membranes of polyphenols and impurities and, therefore, to obtain a reduction in the obstruction and fouling of the membranes, as well as 'increase in the useful life of membranes and recovery of polyphenols. Polyethersulfone and polysulfone membranes should be avoided.

According to a preferred variant of the process that is the subject of the invention, prior to the reuse of the reverse osmosis permeate as a solvent in operation a) or as a supply to the intermediate tank, the reverse osmosis permeate accumulates in a tank distribution before being sent for reuse.

According to a second aspect of the invention, there is disclosed a system for the recovery of polyphenols from solid waste or industrial solid and liquid waste from the food and beverage sector, in which the process described above is carried out. .

• une installation d’extraction de polyphénols assistée par micro-ondes ou par ultrasons qui comprend une chambre ou un réservoir d’extraction apte pour la réception d’un lot des déchets solides, pourvu d’une source d’ultrasons ou de micro-ondes et d’au moins une première entrée par laquelle un solvant apte pour le traitement d’extraction de polyphénols de volumes de solutions par ultrasons ou par micro-ondes est introduit dans la chambre ou le réservoir d’extraction;
• un réservoir intermédiaire dont l’entrée est disposée en communication avec la sortie de l’installation d’extraction, la capacité volumétrique du réservoir intermédiaire étant apte pour l’accumulation d’au moins un volume suffisant de solution ou de solutions traitées dans l’installation d’extraction pour permettre l’opération continu d’un système de séparation qui réalise un processus continu;
• un système de séparation raccordé à la sortie du réservoir intermédiaire, formé d’un sous-système de microfiltration raccordé en série à un sous-système d’ultrafiltration qui est raccordé à son tour en série à un sous-système d’osmose inverse, dans lequel le sous-système de microfiltration comprend une membrane de microfiltration et une sortie pour le perméat de microfiltration raccordée à l’entrée du sous-système d’ultrafiltration, dans lequel le sous-système d’ultrafiltration comprend une membrane d’ultrafiltration et une sortie pour le perméat d’ultrafiltration raccordée à l’entrée du sous-système d’osmose inverse, et dans lequel le sous-système d’osmose inverse comprend une membrane d’osmose inverse et une sortie pour le perméat d’osmose inverse;
• une installation de réutilisation du perméat de l’osmose inverse qui comprend un réservoir de distribution raccordé à la sortie du perméat d’osmose inverse du sous-système d’osmose inverse, et comprend en outre un ou deux des conduits de réutilisation suivants, dans lequel l’un de ces conduits de réutilisation raccorde un tronçon de la sortie du réservoir de distribution à l’intérieur du réservoir d’extraction ou de la chambre de l’installation d’extraction pour la réutilisation du perméat d’osmose inverse comme solvant, et dans lequel l’autre de ces conduits de réutilisation raccorde un tronçon de la sortie du réservoir de distribution à l’intérieur du réservoir intermédiaire pour la réutilisation du perméat de l’osmose inverse comme apport au réservoir intermédiaire pour augmenter la sédimentabilité des solides présents dans le contenu retenu dans le réservoir intermédiaire, protégeant les membranes en évitant qu’elles ne soient obstruées et en diminuant l’encrassement de celles-ci.

The system for the recovery of polyphenols which is the subject of the invention is characterized in that it comprises:

• an installation for the extraction of polyphenols assisted by microwave or ultrasound which comprises an extraction chamber or tank suitable for receiving a batch of solid waste, provided with an ultrasound or microwave source and at least a first inlet through which a solvent suitable for the treatment of extraction of polyphenols from volumes of solutions by ultrasound or by microwave is introduced into the chamber or the extraction tank;
• an intermediate reservoir, the inlet of which is disposed in communication with the outlet of the extraction installation, the volumetric capacity of the intermediate reservoir being suitable for the accumulation of at least a sufficient volume of solution or solutions treated in the extraction installation to allow the continuous operation of a separation system which performs a continuous process;
• a separation system connected to the outlet of the intermediate tank, formed of a microfiltration sub-system connected in series to an ultrafiltration sub-system which is in turn connected in series to a reverse osmosis sub-system, wherein the microfiltration subsystem comprises a microfiltration membrane and an outlet for the microfiltration permeate connected to the inlet of the ultrafiltration subsystem, wherein the ultrafiltration subsystem comprises an ultrafiltration membrane and an outlet for the ultrafiltration permeate connected to the inlet of the reverse osmosis subsystem, and in which the reverse osmosis subsystem comprises a reverse osmosis membrane and an outlet for the reverse osmosis permeate ;
• a reverse osmosis permeate reuse plant which includes a distribution tank connected to the reverse osmosis permeate outlet of the reverse osmosis subsystem, and further includes one or two of the following reuse conduits, in which one of these reuse conduits connects a section of the outlet of the distribution tank to the interior of the extraction tank or the chamber of the extraction installation for the reuse of the reverse osmosis permeate as a solvent , and wherein the other of these reuse conduits connects a section of the outlet of the distribution tank to the interior of the intermediate tank for the reuse of the reverse osmosis permeate as a feed to the intermediate tank to increase the sedimentability of the solids present in the content retained in the intermediate tank, protecting the membranes by preventing them from being clogged and reducing their clogging.

The system object of the invention comprises a pipe or a mixing chamber provided with one or more inlets for the introduction of available industrial liquid waste, arranged either at the inlet or at the outlet of the intermediate tank. Preferably, it is expected that the mixing of the liquid waste with the solid waste (the latter in the form of solutions treated with ultrasound or with microwaves) is behind the intermediate tank, when the intermediate tank is a settling tank, to maximize its ability to separate the solid from the supernatant to be treated in the membranes after extraction. To do this, the extraction installation is first installed in the system, after this the intermediate tank (it can be a settling tank) then there are two alternatives: add only solid waste, mix the solid and liquid wastes previously in the membrane train, or they are fed separately (ie they are mixed in a pipe).

According to another characteristic of the system for the recovery of polyphenols which is the object of the invention, the reuse installation comprises the two reuse conduits, the first reuse conduit being that which connects a section of the outlet of the tank. distribution inside the extraction tank or the chamber of the extraction installation, and the second reuse duct being that which connects a section of the outlet of the distribution tank inside the intermediate tank. Further, the system for the recovery of polyphenols includes control means programmed to receive the transmembrane pressure value of the membrane microfiltration process at a time or time interval, and decide and control the introduction of the osmosis permeate. reverse in the first reuse duct or in the second reuse duct depending on the result of an operation to compare the transmembrane pressure value of the microfiltration process at an instant or time interval, with a predefined membrane protection threshold value . When such a transmembrane pressure value is equal to or greater than such a threshold value, the control means will activate and monitor the introduction of the reverse osmosis permeate into the second reuse duct, and when such a transmembrane pressure value is less than the threshold value, the control means will activate and control the introduction of the permeate into the first reuse duct.

In accordance with a particular embodiment of the system which is the subject of the invention, a section of the outlet of the distribution tank is provided with a bifurcation through which said section is connected on one side to the first reuse duct and on the other. side to the second reuse duct. The control means in this variant are programmed to act on the bifurcation and deactivate the connection with the second reuse duct so that the section of the outlet of the distribution tank communicates only with the second inlet to the extraction tank or to the chamber of the extraction installation, and if the transmembrane pressure value in real time is equal to or greater than the membrane protection threshold value, the control means are programmed to act on the bifurcation and only activate the connection with the second reuse duct so that the section of the outlet of the distribution tank communicates only with an inlet to the intermediate tank.

The membrane protection threshold value is between 5 and 1000kPa, preferably between 50 and 300kPa. A more restrictive threshold value can also be considered, between 100 and 150kPa. In all cases, the threshold value which is defined ultimately depends on the type of membrane and the manufacturer's recommendations.

Preferably, provision is made for a reservoir between the microfiltration membrane and the ultrafiltration membrane. Optionally, a reservoir can also be provided between the ultrafiltration membrane and the reverse osmosis membrane. Thus, in the event that a high transmembrane pressure (from a value defined as "high") which can damage the ultrafiltration membrane or the reverse osmosis membrane is detected, the possibility of diverting the permeate from the osmosis reverse to one or more of these reservoirs prior to the ultrafiltration or reverse osmosis membranes is envisaged.

Provision is also made for the system which is the subject of the invention to comprise a reservoir for supplying solvent (preferably ethanol) for the supply controlled by the means for controlling a quantity of solvent through an inlet of the extraction reservoir. or the chamber of the installation for extracting polyphenols assisted by microwave or ultrasound.

Advantageously, the system that is the subject of the invention can include centrifugation means arranged between the extraction installation and the intermediate tank, to minimize the presence of solids in the flow which enters the intermediate tank. Alternatively, the intermediate tank or the extraction tank (or chamber of the extraction installation) can be formed as a settling tank.

As for the parameters to be considered in the choice of membranes, the membranes are preferably hydrophobic, the size of the pores of the membrane of the ultrafiltration subsystem is between 5 and 10 kDa, and the size of the particles of the osmosis membrane. inverse is between 50 and 120Da, to achieve a good separation of the polyphenol extract and the solvent stream, and that the recovery of polyphenols is thus maximized and at the same time a high purity permeate is obtained, suitable for being used directly as a solvent in the extraction operation a). Thus, in the serial operations of microfiltration, ultrafiltration and reverse osmosis, the membranes are not only configured for the successive separation of the permeate from the colloidal material, polysaccharides and polyphenols, but also allow a mixture of 'water and ethanol (or other similar solvent), already present in the supernatant of the intermediate tank, to remain in the successive permeates so that this permeate, having finally passed through the reverse osmosis membrane, can be introduced into the installation extraction assisted by ultrasound or microwave as a solvent.

Finally, provision is made for the system which is the subject of the invention to comprise an ethanol supply tank for the supply controlled by the control means of a quantity of ethanol through the first inlet to the extraction tank or to the outlet. chamber of the polyphenol extraction plant assisted by microwave or ultrasound.

Brief description of the drawings

To complete the description which is in the process of being made and with the object of facilitating the understanding of the characteristics of the invention, a set of drawings is accompanied with this descriptive memory in which, by way of illustration and not limitation, it has have been represented as follows:

the is a schematic view of a first embodiment of the polyphenol recovery system object of the invention which also represents the solid waste and industrial liquid waste from the food and beverage sector from which the polyphenols are recovered according to the process which is also the object of the present invention, in which the chamber of the extraction installation (or extraction tank) is configured as a settling tank and in which the liquid waste is supplied downstream of the intermediate tank;

the is a schematic view of a second embodiment of the polyphenol recovery system object of the invention in which, unlike the first embodiment, the intermediate tank is configured as a settling tank;

the is a schematic view of a third embodiment of the polyphenol recovery system object of the invention in which, unlike the second embodiment, centrifugation means are arranged between the extraction installation and the intermediate tank, and the intermediate tank does not have a settling tank configuration;

the is a schematic view of a fourth embodiment of the polyphenol recovery system object of the invention in which, unlike the first embodiment, the liquid waste is supplied by a pipe between the extraction installation and the reservoir intermediate to be introduced into the intermediate reservoir; and

the is a schematic view of a fifth embodiment of the polyphenol recovery system object of the invention in which, unlike the second embodiment, the liquid waste is supplied by a pipe between the extraction installation and the reservoir intermediate to be introduced into the intermediate reservoir.

Detailed description of the embodiment

The to 5 show a system 100 for the recovery of polyphenols from solid waste 92 and industrial liquid waste 93 from the food and beverage sector, such as those from the olive oil and olive oil industry. wine. It is observed that the system 100 firstly comprises an installation 1 for extracting polyphenols assisted by microwave or ultrasound which in turn comprises a container or a chamber suitable for receiving a batch of solid waste 92, provided of an ultrasound or microwave source 13 and of first and second inputs through which a solvent suitable for the treatment of extraction of polyphenols from volumes of solutions by ultrasound or by microwave is introduced into the reservoir of extraction or the chamber of the extraction installation. The first inlet is connected to a solvent supply reservoir 12 (preferably an ethanol reservoir) for the supply controlled by control means 70 of a quantity of ethanol to the container or the chamber of the installation. extraction 1. The second inlet, shown to the right of the first, receives a mixture of water and solvent (preferably ethanol) reused as solvent and which comes, as will be explained below, from a reservoir distribution 7.

In the extraction plant 1 the solid waste 92 is subjected to the batch extraction operation and respective batches of treated solution volumes 10 are obtained.

Hereinafter, the volumes of solution treated 10 are introduced and retained in an intermediate tank 3, the volumetric capacity of which is suitable for the accumulation of at least a sufficient volume of solution or solutions treated in the extraction installation 1. to enable the continuous operation of a separation system which performs a continuous process which includes the serial operations of membrane microfiltration, ultrafiltration of the membrane microfiltration permeate 40 and membrane reverse osmosis of the ultrafiltration permeate 50. From the intermediate reservoir 3, all or part of its content as feed for this continuous process is impelled, for example, through a pump (not shown in the figures). As the output of the volumes of treated solution 10 from the extraction plant 1 is not continuous (it is in batches), the intermediate tank ensures that there is sufficient quantity or volume to be able to operate continuously throughout the entire process. the duration of the total operating cycle in the extraction installation 1, and not only when the discharge of the extraction installation 1 is made.

• en aval du réservoir intermédiaire 3, comme c’est le cas des systèmes représentés sur les Fig. 1, 2 et 3; ou
• avant le réservoir intermédiaire 3 pour être introduits et retenus dans celui-ci, comme c’est le cas des systèmes 100 représentés sur les Fig. 4 et 5.

As noted, system 100 allows the recovery of polyphenols from solid waste 92 and furthermore also from liquid waste 93. Liquid waste 93 can be introduced into system 100 at one of the following locations:

• downstream of the intermediate reservoir 3, as is the case with the systems shown in FIGS. 1, 2 and 3; Where
• before the intermediate reservoir 3 to be introduced and retained therein, as is the case with the systems 100 shown in FIGS. 4 and 5.

For this, the system 100 comprises a pipe or a mixing chamber provided with one or more inlets for the introduction of available industrial liquid waste 93, arranged either at the inlet or at the outlet of the intermediate tank 3.

We observe on the how a separation system is connected to the outlet of the intermediate tank 3, said separation system being formed of a microfiltration subsystem 42 connected in series with an ultrafiltration subsystem 52, which in turn is connected in series to a reverse osmosis subsystem 62. The microfiltration subsystem 42 comprises a microfiltration membrane 4 and an outlet for the microfiltration permeate 40 which in turn is connected to the inlet of the subsystem. ultrafiltration 52. The ultrafiltration subsystem 52 comprises an ultrafiltration membrane 5, with a pore size preferably between 5 and 10 kDa, and an outlet for the ultrafiltration permeate 50, in turn connected to the ultrafiltration membrane. inlet of the reverse osmosis subsystem 62. The reverse osmosis subsystem 62 comprises a reverse osmosis membrane 6 with a particle size between 50 and 120Da and an outlet for the reverse osmosis permeate 60. Preferably, the separati A reservoir is described between the microfiltration membrane 4 and the ultrafiltration membrane 5, and another reservoir between the ultrafiltration membrane 5 and the reverse osmosis membrane 6. From each subsystem there are two outlets, the first known as permeate (40, 50 and 60) and the second known as reject (41, 51 and 61).

The reason and configuration of the membrane train 4, 5, and 6 is as follows. First, the flow at the outlet of the intermediate tank 3 is subjected to a microfiltration step, to eliminate the presence of solids, mainly colloidal material 41 which is retained constituting the reject flow, and to minimize fouling and the obstruction of membranes 4, 5 and 6 of the following steps present in the respective subsystems. The permeate from microfiltration 40 is treated in an ultrafiltration step to purify and concentrate the polyphenol-rich stream. In the case of the ultrafiltration membrane 5, the pore size of the membrane is between 5 and 10kDa, necessary to purify the flow of polyphenols and reduce the presence of proteins and carbohydrates in the permeate of the ultrafiltration 50. The reject from ultrafiltration contains 51 polysaccharides in high concentration and after short evaporation can be used as animal feed. On the other hand, the permeate from the ultrafiltration 50 is finally subjected to a reverse osmosis process to maximize the recovery and concentrate the flow of polyphenols 61. The flow rich in polyphenols 61 retained in the reverse osmosis can be used in System 100's own facilities to produce products enriched with antioxidants or to be sold to external customers. Reverse osmosis makes it possible to obtain a flow of permeate 60 of high purity, said reverse osmosis permeate 60 being formed of a mixture of water and solvent (preferably ethanol or a similar compound), for which the particle size 6 of the reverse osmosis membrane is between 50 and 120Da, which is necessary to achieve a good separation between the polyphenol 61 extract and the flow of the mixture of water and solvent (osmosis permeate inverse 60).

In addition, the microfiltration membrane 4, the ultrafiltration membrane 5 and the reverse osmosis membrane 6 are hydrophobic membranes, to avoid the absorption into the membranes of polyphenols and impurities and, therefore, achieve a reduction in clogging and fouling of membranes, as well as increasing their useful life and recovery of polyphenols. Polyethersulfone and polysulfone membranes should be avoided.

• un réservoir de distribution 7 raccordé à la sortie du perméat d’osmose inverse 60 du sous-système d’osmose inverse 62;
• un premier conduit de réutilisation 71 qui raccorde un tronçon de la sortie du réservoir de distribution 7 à l’intérieur du conteneur ou de la chambre de l’installation d’extraction 1 pour la réutilisation du perméat de l’osmose inverse 60 comme solvant dans l’opération d’extraction par ultrasons ou par micro-ondes;
• un deuxième conduit de réutilisation 72 qui raccorde un tronçon de la sortie du réservoir de distribution 7 à l’intérieur du réservoir intermédiaire 3 pour la réutilisation du perméat de l’osmose inverse 60 comme apport au réservoir intermédiaire 3 pour diminuer la concentration de solides et protéger les membranes 4, 5 et 6 en évitant leur encrassement et obstruction;
• des moyens de contrôle 70 programmés pour recevoir la valeur de pression transmembranaire du processus de microfiltration membranaire 4 à un moment ou à un intervalle de temps, et décider et contrôler l’introduction du perméat d’osmose inverse 60 dans le premier conduit de réutilisation 71 ou dans le deuxième conduit de réutilisation 72 selon le résultat d’une opération de comparer la valeur de pression transmembranaire du processus de microfiltration à un instant ou à un intervalle de temps, avec une valeur seuil prédéfinie de protection de membranes, l’introduction du perméat d’osmose inverse 60 résultant dans le deuxième conduit de réutilisation 72 lorsqu’une telle valeur de pression transmembranaire est égale ou supérieure à une telle valeur seuil, et dans le premier conduit de réutilisation 71 lorsqu’une telle valeur de pression transmembranaire est inférieure à la valeur seuil.

As can be seen on the at 5, the system 100 includes a reverse osmosis permeate reuse plant 60 which in turn comprises:

• a distribution tank 7 connected to the outlet of the reverse osmosis permeate 60 of the reverse osmosis subsystem 62;
• a first reuse duct 71 which connects a section of the outlet of the distribution tank 7 inside the container or the chamber of the extraction installation 1 for the reuse of the reverse osmosis permeate 60 as a solvent in ultrasonic or microwave extraction operation;
• a second reuse duct 72 which connects a section of the outlet of the distribution tank 7 inside the intermediate tank 3 for the reuse of the reverse osmosis permeate 60 as a supply to the intermediate tank 3 to reduce the concentration of solids and protect the membranes 4, 5 and 6 by preventing their fouling and obstruction;
• control means 70 programmed to receive the transmembrane pressure value of the membrane microfiltration process 4 at a time or at an interval of time, and to decide and control the introduction of the reverse osmosis permeate 60 into the first reuse duct 71 or in the second reuse duct 72 according to the result of an operation to compare the transmembrane pressure value of the microfiltration process at an instant or at an interval of time, with a predefined threshold value of membrane protection, the introduction of the reverse osmosis permeate 60 resulting in the second reuse duct 72 when such a transmembrane pressure value is equal to or greater than such a threshold value, and in the first reuse duct 71 when such a transmembrane pressure value is lower to the threshold value.

In the at 5, it can be seen how a section of pipe to the outlet of the distribution tank 7 is provided with a bifurcation 73 through which it is connected on one side to the first reuse pipe 71 and on the other side to the second pipe reuse 72. The control means 70 are programmed to act on the bifurcation 73 and deactivate the connection with the second reuse duct 72 so that the section of the outlet of the distribution tank 7 communicates only with the second inlet to the reservoir d 'extraction or to the chamber of the extraction installation 1, and if the transmembrane pressure value in real time is equal to or greater than the membrane protection threshold value, the control means 70 are programmed to act on the bifurcation 73 and activate only the connection with the second reuse duct 72 so that the section of the outlet of the distribution tank 7 communicates only with an inlet of the reuse. intermediate servoir 3.

The membrane protection threshold value can be between 5 and 1000kPa, although preferably it has been defined as a value between 50 and 300kPa, a more restrictive value, such as a chosen value and between 100 and 150kPa which can be be considered in some cases. In all cases, the threshold value which is defined ultimately depends on the type of membrane and the manufacturer's recommendations. Thus, the transmembrane pressure is monitored or controlled in the microfiltration step, for example by the measurer 74 or similar means, and in the event that values equal to or greater than the range of the protective threshold value are reached. (for example, defined between 50 and 1300 kPa, the control means 70 recirculate the reverse osmosis permeate 60 to the intermediate tank 3, instead of recirculating it to the extraction installation 1, to increase the sedimentation capacity and reducing the concentration of solids at the entrance to the microfiltration membrane 4. In this way, although the main function of the control means 70 is the recovery of the solvent (the permeate which results from the reverse osmosis 60) for it. reuse in the extraction operation, the second function will take priority if necessary.

System 100 shown in envisages that the system 100 is provided with centrifugation means arranged between the extraction installation 1 and the intermediate tank 3, to minimize the presence of solids in the flow which enters the intermediate tank 3. The systems 100 shown in the and 4 do not have said centrifugation means, but in order to minimize the presence of solids in the flow which will later pass to the membrane separation system, the extraction tank or the chamber of the extraction installation 1 is formed as a settling tank, where at the bottom of the latter the solid matter in suspension settles and the supernatant of the extraction tank will feed the intermediate tank 3. On the other hand, in the and 5, it is the intermediate tank 3 of the system 100 which is configured as a settling tank.

In summary, the system 100 described above makes it possible to carry out the process for the recovery of polyphenols from solid waste 92 and industrial liquid waste 93 from the food and beverage sector, which comprises the operations of:
a) subjecting the solid waste 92, in batches, to a polyphenol extraction operation by adding a solvent and to the action of an ultrasound or microwave source 13 to obtain treated volumes of solution 10;
b) introducing and retaining in the intermediate reservoir 3 one or more volumes of treated solution 10;
c) propel all or part of the content retained in the intermediate tank 3 as feed for the continuous process which comprises the serial operations of membrane microfiltration 4, ultrafiltration of the permeate, membrane microfiltration 40 5 and reverse osmosis membrane 6 of the permeate ultrafiltration 50, and
d) reuse the reverse osmosis permeate 60 as a solvent in operation a) or as a contribution to the intermediate tank 3 to increase the sedimentability of the solids present in the content retained in the intermediate tank 3, protecting the membranes 4, 5, 6 by preventing them from being clogged and reducing their clogging.

As has been explained with regard to the system 100, and in particular with reference to the control means 70, the reuse of the reverse osmosis permeate 60 as a solvent in operation a) or as a supply to the intermediate tank 3 is the result of '' an operation to compare the transmembrane pressure value of the microfiltration process with a predefined membrane protection threshold value (preferably between 50 and 300kPa) the resulting reuse as input to the intermediate tank 3 when such a transmembrane pressure value is equal or greater than such a threshold value, and as a solvent in step a) when it is lower.

As has been commented on above, the introduction of the liquid waste 93 into the system 100 so that they can be treated and recover the polyphenols therefrom can be done at different points, for example, introduce them before the intermediate tank 3 by them. joining before the volumes of solution treated 10 coming from the extraction installation 1, or that they arrive at the intermediate tank 3 whatever the said volumes of solution treated 10, or that they are introduced into the system 100 downstream of the intermediate tank 3, at the inlet of the microfiltration sub-system 42, mixed or not with the flow coming from the outlet of the intermediate tank 3.

Claims (22)

Process for the recovery of polyphenols from solid waste (92) or solid waste (92) and liquid waste (93) from the food and drink sector, characterized in that it comprises the operations of:
a) subjecting the solid waste (92), in batches, to a polyphenol extraction operation by adding a solvent and to the action of an ultrasound or microwave source (13) to obtain solution volumes treated (10);
b) introduce and retain in an intermediate reservoir (3) one or more volumes of treated solution (10)
c) propel all or part of the content retained in the intermediate tank (3) as feed for a continuous process which includes the series operations of membrane microfiltration (4), of ultrafiltration of the permeate of membrane microfiltration (40) (5) ) and membrane reverse osmosis (6) of the permeate from the ultrafiltration (50),
the method further comprising re-using the permeate from reverse osmosis (60) as a solvent in step a) or as a feed to the intermediate tank (3) to increase the sedimentability of the solids present in the contents retained in the intermediate tank (3), protecting the membranes by preventing them from being clogged and reducing their clogging. Process for the recovery of polyphenols according to claim 1, characterized in that the reuse of the reverse osmosis permeate (60) as a solvent in step a) or as a supply to the intermediate tank (3) is the result of a operation of comparing the value of the transmembrane pressure of the microfiltration process with a predefined threshold value of membrane protection, the resulting reuse as a contribution to the intermediate reservoir (3) when such a value of transmembrane pressure is equal to or greater than such a value threshold, and as solvent in step a) when it is lower. Process for the recovery of polyphenols according to Claim 2, characterized in that the membrane protection threshold value is between 5 and 1000 kPa. Process for the recovery of polyphenols according to Claim 3, characterized in that the membrane protection threshold value is between 50 and 300 kPa. Process for the recovery of polyphenols according to Claim 4, characterized in that the membrane protection threshold value is between 100 and 150kPa. Process for the recovery of polyphenols according to any one of the claims, characterized in that the suspended colloidal material is retained in the membrane microfiltration operation (4), the polysaccharides are retained in the membrane ultrafiltration operation (5) and polyphenols are retained in the membrane reverse osmosis operation (6), the membrane pore size (5) of the ultrafiltration process to purify the flow of polyphenols and reduce the presence of proteins and carbohydrates in the ultrafiltration permeate (50) being between 5 and 10kDa. Process for the recovery of polyphenols according to any one of the claims, characterized in that in step a) the solvent is ethanol or a mixture of ethanol and water, and in that the permeate of the reverse osmosis (60) reused as solvent in step a) is a mixture of ethanol and water. Process for the recovery of polyphenols according to any one of the preceding claims, characterized in that the treated solution volumes (10) are subjected to a decantation process before the microfiltration operation of the continuous process, the decantation taking place either in the extraction installation where the polyphenol extraction operation is carried out, either before they are introduced into the intermediate tank (3) because they are subjected to a centrifugation operation to reduce the content in solids prior to their introduction, or in the intermediate tank (3) because the latter is formed as a settling tank. Process for the recovery of polyphenols according to any one of the preceding claims, characterized in that the process is carried out from industrial liquid waste (93) from the food and beverage sector, in addition to solid waste (92) , in which the liquid wastes (93) are introduced and retained in the intermediate tank (3), or they are introduced downstream of the intermediate tank (3) and propelled as feed for the continuous process of membrane microfiltration (4), from membrane ultrafiltration (5) of the permeate of membrane microfiltration (40) and membrane reverse osmosis (6) of the permeate of the ultrafiltration (50). Process for the recovery of polyphenols according to any one of the claims, characterized in that prior to the reuse of the reverse osmosis permeate (60) as a solvent in operation a) or as a supply to the intermediate reservoir, said permeate accumulates in a distribution tank (7) before being sent for reuse. System (100) for the recovery of polyphenols from solid waste (92) or solid waste (92) and liquid waste (93) from the food and beverage sector, characterized in that it comprises:
- an extraction installation (1) for polyphenols assisted by microwave or ultrasound which comprises an extraction chamber or tank suitable for receiving a batch of solid waste (92), provided with a source of ultrasound or microwave (13) and at least a first inlet through which a solvent suitable for the treatment of extraction of polyphenols from volumes of solutions by ultrasound or by microwave is introduced into the chamber or the extraction tank;
- an intermediate tank (3) whose inlet is arranged in communication with the outlet of the extraction installation (1), the volumetric capacity of the intermediate tank (3) being suitable for the accumulation of at least one volume sufficient solution or solutions treated in the extraction plant (1) to allow the continuous operation of a separation system which carries out a continuous process;
- a separation system connected to the outlet of the intermediate tank (3), formed of a microfiltration sub-system (42) connected in series to an ultrafiltration sub-system (52) which is in turn connected in series to a reverse osmosis subsystem (62), in which the microfiltration subsystem (42) comprises a microfiltration membrane (4) and an outlet for the microfiltration permeate (40) connected to the inlet of the sub -Ultrafiltration system (52), in which the ultrafiltration subsystem (52) comprises an ultrafiltration membrane (5) and an outlet for the ultrafiltration permeate (50) connected to the inlet of the sub- reverse osmosis system (62), and wherein the reverse osmosis subsystem (62) comprises a reverse osmosis membrane (6) and an outlet for the reverse osmosis permeate (60);
- an installation for reuse of the reverse osmosis permeate (60) which comprises a distribution tank (7) connected to the outlet of the reverse osmosis permeate (60) of the reverse osmosis subsystem (62), and further comprises one or two of the following reuse conduits (71, 72), wherein one of these reuse conduits (71) connects a section of the outlet of the distribution tank (7) to the interior of the distribution tank. 'extraction or from the chamber of the extraction plant (1) for the reuse of the reverse osmosis permeate (60) as a solvent, and in which the other of these reuse pipes (72) connects a section of the outlet of the distribution tank (7) inside the intermediate tank (3) for the reuse of the reverse osmosis permeate (60) as a contribution to the intermediate tank (3) to increase the sedimentability of the solids present in the contents retained in the intermediate tank (3) protecting the membranes (4, 5, 6) avoiding that they are clogged and reducing the clogging of these. System (100) for the recovery of polyphenols according to claim 11, characterized in that the re-use installation comprises the two re-use conduits, the first re-use conduit (71) being that which connects a section of the outlet of the storage tank. distribution (7) inside the extraction tank or the chamber of the extraction installation (1), and the second reuse duct (72) being that which connects a section of the outlet of the distribution tank (7) inside the intermediate tank (3), and in that the system (100) for the recovery of polyphenols comprises control means (70) programmed to receive the transmembrane pressure value of the membrane microfiltration process ( 4) at a time or time interval, and decide and control the introduction of the reverse osmosis permeate (60) into the first reuse conduit (71) or the second reuse conduit (72) depending on the reuse. result of an operation to compare the transmembrane pressure value of the microfiltration process at an instant or at an interval of time, with a predefined threshold value of membrane protection, the introduction of the reverse osmosis permeate (60) resulting in the second reuse duct (72) when such a transmembrane pressure value is equal to or greater than such a threshold value, and in the first reuse duct (71) when such a transmembrane pressure value is less than the threshold value . System (100) for the recovery of polyphenols according to Claim 12, characterized in that a section of the outlet of the distribution tank (7) is provided with a bifurcation (73) through which it is connected on one side to the first reuse duct (71) and on the other side to the second reuse duct (72), and in that the control means (70) are programmed to act on the bifurcation (73) and deactivate the connection with the second reuse duct (72) so that the section of the outlet of the distribution tank (7) communicates only with the second inlet to the extraction tank or to the chamber of the extraction installation (1), and if the transmembrane pressure value in real time is equal to or greater than the membrane protection threshold value, the control means (70) are programmed to act on the bifurcation (73) and only activate the connection with the second reuse duct (72 ) so that the section of the outlet of the distribution tank (7) communicates only with an inlet of the intermediate tank (3). System (100) for the recovery of polyphenols according to claim 12 or 13, characterized in that the membrane protection threshold value is between 5 and 1000 kPa. System (100) for the recovery of polyphenols according to Claim 14, characterized in that the membrane protection threshold value is between 50 and 300 kPa. System (100) for the recovery of polyphenols according to Claim 15, characterized in that the membrane protection threshold value is between 100 and 150kPa. System (100) for the recovery of polyphenols according to any one of claims 11 to 16, characterized in that it comprises centrifugation means arranged between the extraction installation (1) and the intermediate tank (3). System (100) for the recovery of polyphenols according to any one of claims 11 to 16, characterized in that at least the intermediate tank (3) or the extraction tank or the chamber of the extraction installation ( 1) is formed as a settling tank. System (100) for the recovery of polyphenols according to any one of claims 11 to 18, characterized in that the size of the pores of the membrane (5) of the ultrafiltration subsystem (52) is between 5 and 10kDa and the particle size of the reverse osmosis membrane (6) is between 50 and 120Da. System (100) for the recovery of polyphenols according to any one of claims 11 to 19, characterized in that the microfiltration membrane (4) of the microfiltration subsystem (42), the ultrafiltration membrane (5) of the Ultrafiltration subsystem (52) and the reverse osmosis membrane (6) of the reverse osmosis subsystem (62) are hydrophobic membranes. System (100) for the recovery of polyphenols according to any one of claims 11 to 20, characterized in that it comprises a supply reservoir (12) of ethanol for the supply controlled by the control means (70) d a quantity of ethanol through the first inlet of the extraction tank or of the chamber of the extraction installation (1) of polyphenols assisted by microwave or ultrasound. System (100) for the recovery of polyphenols according to any one of claims 11 to 21, characterized in that it comprises a pipe or a mixing chamber provided with one or more inlets (22) for the introduction of industrial liquid waste (93) available at the inlet or outlet of the intermediate tank (3).