ES1303753U - A system for the recovery of polyphenols from solid waste or solid waste and industrial liquid waste from the food and beverage sector (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

A 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) of polyphenols assisted by microwave or ultrasound that comprises an extraction chamber or tank suitable for receiving a batch of solid waste (92), provided with an ultrasound or microwave source (13) and at least a first inlet through which a solvent suitable for the extraction treatment of polyphenols from volumes of solutions by ultrasound or microwave is introduced into the extraction chamber or 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 a sufficient volume of solution or solutions treated in the extraction installation (1) to allow the continuous operation of a separation system that carries out a continuous process; - a separation system connected to the outlet of the intermediate tank (3), formed by a microfiltration subsystem (42) connected in series to an ultrafiltration subsystem (52) which in turn is 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 ultrafiltration subsystem (52), in which the subsystem The ultrafiltration system (52) comprises an ultrafiltration membrane (5) and an outlet for the ultrafiltration permeate (50) connected to the inlet of the reverse osmosis subsystem (62), and wherein the reverse osmosis subsystem (62) comprises a reverse osmosis membrane (6) and an outlet for the reverse osmosis permeate (60); - a reverse osmosis permeate reuse facility (60) comprising a distribution tank (7) connected to the reverse osmosis permeate outlet (60) of the reverse osmosis subsystem (62), and further comprising two reuse (71, 72), the first reuse conduit (71) being the one that connects a section of the outlet of the distribution tank (7) with the interior of the extraction tank or chamber of the extraction installation (1) for reuse of the reverse osmosis permeate (60) as a solvent, and the second reuse conduit (72) which connects a section of the outlet of the distribution tank (7) with the interior of the intermediate tank (3) for the reuse of the permeate from reverse osmosis (60) as a contribution to the intermediate tank (3); - control means (70) programmed to receive the transmembrane pressure value of the membrane microfiltration process (4) at a moment or time interval and compare it with a pre-established membrane protection threshold value, and programmed to decide and control introducing the reverse osmosis permeate (60) into the first reuse conduit (71) or into the second reuse conduit (72). (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

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

Technical sector of invention

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

Background of the invention

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

In the wine industry it is known that of the phenolic compounds, anthocyanins and the pigments derived from them, produced through copigmentation or condensation processes, are the compounds that most influence the color of red and rosé wines, giving rise to orange colors, red, violet or blue. The transfer of the phenolic compounds responsible for the color from the skins to the liquid phase (must) after a crushing process is closely related to the raw material and the winemaking techniques used and is decisively influenced by the variety, the degree of ripening and size of the grape, as explained in the Spanish patent ES2478190-B2. This patent refers to a procedure, a module and equipment for the extraction of compounds from grapes using ultrasound in winemaking processes, and in particular to the transfer of the phenolic compounds responsible for the color from the skin to the liquid part ( must) after crushing the grapes, using a procedure and equipment based on the generation of ultrasound. Due to the use of Ultrasound generates the phenomenon of cavitation, which allows the rupture of the skin cells and makes the phenolic compounds responsible for the color available to the liquid medium so that they can be integrated into said liquid medium, enhancing the color of the wine.

Another application of polyphenols, this time in the olive oil industrial sector, is the one proposed in the patent application document EP2994225-A1, in which a reactor is described to increase the amount 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 to obtain extra virgin olive oil, and at least one ultrasound source adapted to vibrate the body of said cavity.

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

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

With this objective, the AINIA technology center has developed an industrial plant (known by the name ALTEX) for the extraction of supercritical CO ² to recover polyphenols, with an extraction capacity of 4,000 liters. Although recovery of polyphenols from industrial waste is carried out effectively, it has certain limitations such as high energy consumption or the high initial investment (CAPEX) required, which can limit its viability.

Spanish patent ES 2319032-B1 describes a procedure for extracting polyphenols from grape pomace from distillation that is based on the collection of residual pomace from the distillation process carried out by steam drag and direct fire. An extraction of the polyphenols from said pomace is carried out by using a hydroalcoholic mixture (ethanol/water acidified to pH 1, 50:50), at a temperature of 40-55°C and for a time of 3-4 hours. After the extraction process, said stream is cooled to 25°C and purified by filtration at 100 microns and subsequent centrifugation to eliminate precipitated solids. The liquid obtained is stabilized by adding 0.20 to 0.60 g of sodium alginate per liter of polyphenolic extract and concentrated up to 50%, recovering a 70:30 ethanol/water condensate, for reintroduction into the process. .

This procedure is based on a conventional solid-liquid extraction, so an extraction procedure that would improve the polyphenol recovery performance, reduce extraction time and solvent needs would be desirable.

The Spanish patent ES2455999-T3 describes a procedure for obtaining a natural concentrate rich in hydroxytyrosol from waste and by-products of the olive tree, which consists of the following stages: a) processing the solid and semi-solid waste from the olive tree by means of extraction with water or with hydroalcoholic mixtures, b) either supply the extract containing hydroxytyrosol and other bioactive compounds from the olive tree directly to a nanofiltration unit with a cut-off molecular weight of less than 300 Da, or mix the extract obtained in step a. ) with the vegetable waters from the olive grindings and centrifuge in order to eliminate particles and other suspended solids, and supply the supernatant obtained from the centrifuge to said nanofiltration unit, in which said hydroxytyrosol and other low-weight bioactive compounds molecular are recovered in a permeate stream of said nanofiltration unit, and c) supplying the permeate stream of said nanofiltration unit to the supply compartment of a reverse osmosis unit, in which said hydroxytyrosol and other bioactive compounds are retained and concentrated in a retentate stream. As a drawback, it is worth mentioning that conventional extraction involves a long extraction time and high solvent consumption, which increases the operating cost and has a lower extraction yield compared to other more advanced extraction solutions for polyphenols. The application of conventional extraction makes coupling to a membrane treatment difficult since the latter works in continuous mode and conventional extraction entails a long extraction time.

In relation to oil mill wastewater and its content in compounds of interest to the cosmetic, pharmaceutical, dietetic and food industries, patent ES2335418-T3 discloses a procedure for the recovery of tyrosol and hydroxytyrosol from oil mill wastewater, as well as as a catalytic oxidation method in order to convert tyrosol to hydroxytyrosol. The procedure in question consists of a stage a) of coarse filtration or prefiltration, microfiltration, ultrafiltration, nanofiltration and reverse osmosis of water, preferably at a neutral or alkaline pH, a stage b) of chromatographic separation of tyrosol, hydroxytyrosol and other compounds phenolics of the concentrate or rejection of reverse osmosis, a step c) of oxidation of the tyrosol thus obtained to give hydroxytyrosol in the presence of methylrenium trioxide and hydrogen peroxide in a protic solvent, and a step d) of concentration and spraying of the high molecular weight portion with the recovery of water and compounds with a high added value.

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

Patent ES2595939-B1 refers to a procedure to recycle and reuse liquid effluents from olive oil extraction. The procedure is aimed at reducing the consumption of drinking water, reusing wastewater and also, on the other hand, preventing some compounds, such as phenolics, from being wasted in wastewater. The procedure consists of passing the residual washing or vegetable water through a filtration system that includes, at least, a filter placed downstream of the separation equipment; introduce the reused water into a compensation tank with drinking water, placed upstream of the separation equipment for the olive oil extraction procedure; and reintroducing the water mixture into the phase separation unit.

Thus, what is actually done is to use the recycled water, which still contains polyphenols, for the three-phase extraction of olive oil. The separation is relatively simple since in reality there is no isolated recovery of the polyphenols but rather the polyphenols present are reintroduced as part of the recycled water in the olive oil extraction process.

The Spanish patent ES2641069-T3 discloses a procedure for the extraction and concentration of polyphenolic compounds contained in vegetation waters and/or residues obtained from the processing of olives that comprises a stage 1) of collecting the liquid that consists of vegetation waters and /or pomace after the olive grinding procedure; a stage 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 ceramic microfiltration, thus obtaining a concentrate fraction and a permeate fraction; and a stage 4) of vacuum evaporation of the permeate phase obtained in stage 3). Pretreatment 2) 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 with hydraulic agitation by operating a procedure for the recirculation of the same liquid eccentrically with respect to the wall of the reactor, in which said agitation is maintained for a time of 2 to 6 h, preferably for approximately 4 hours. h at a temperature in the range of 30 to 50°C when working with vegetation water, and said hydraulic agitation is maintained for 12-24 h at a temperature in the range of 50 to 80°C when working with pomace. Pretreatment 2) also comprises a stage c) of elimination of the solid or semi-solid residue that is collected on the surface at the end of said stage b) where said residue has a density between 0.70 and 0.85 g/cm3, in wherein said removal takes place by pumping and sending the liquid mass collected at the bottom of the pretreatment tank to the subsequent filtration section and said plug constitutes 2-7% by weight with respect to the total mass of the vegetation water and contains approximately 20% of the solids present in the initial vegetation waters.

In this procedure, the microfiltration permeate is directly evaporated after an enzymatic pretreatment, so the obtained polyphenol extract will contain polysaccharides and other impurities because it cannot be separated by a microfiltration membrane alone. Furthermore, a high operating cost related to evaporation energy (pressure and heat) is expected, because evaporation is applied to the entire microfiltration permeate. Furthermore, enzymatic hydrolysis does not reduce operation times compared to conventional extraction. Another drawback is that polyphenols have different polarities, so extraction with just water makes it difficult to extract non-polyphenols. polar.

In relation to the wine sector, patent ES2319032-B1 describes a procedure for extracting polyphenols from grape pomace from distillation that includes the following steps: a) extraction of the pomace by continuous countercurrent diffusion using a solution 50 as extractant: 50 of ethanol: acidified water at pH 1, at a temperature of 40-55°C and for a time of 3-4 hours, with the extraction ratio pomace: extractant in the range 1:2-3.5, obtaining a extraction pomace and an extraction juice; b) pressing the extraction pomace resulting from step a) at a pressure between 2 and 10 kg/cm2, obtaining a pressing pomace and a pressing juice; c) mixture of the extraction juice obtained in stage a) and the pressing juice obtained in stage b), followed by cooling the resulting mixture to 25°C, purifying it by filtration at 100 microns and centrifugation, obtaining a clarified juice and a solid residue; d) stabilization of the clarified juice obtained in step c) by adding sodium alginate in a concentration of 0.2-0.6 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%, in such a way that a polyphenolic extract with an antioxidant power in a range between 150,000 and 250,000 mg gallic acid/kg of dry pomace.

A drawback of this process is that polysaccharides, sugars and other impurities cannot be separated by prefiltration and evaporation.

Previously, it has been shown that one of the main problems of solid-liquid extraction is its high consumption of solvent and/or its regeneration (evaporation), which results in an increase in operating costs and reduces the sustainability of the process. The development of new extraction techniques without the need for organic solvents (pressure extraction, supercritical extraction with CO ² ) has also been presented. However, these new techniques increase energy consumption, without reducing extraction time, and may reduce polyphenol recovery yield due to limited extraction of hydrophilic polyphenols.

For these reasons, the use of other advanced extractions is proposed as an alternative, such as using ultrasound or microwaves to improve solid-liquid extraction using a mixture of organic solvents and water, which can be efficient. in the recovery of polyphenols from waste generated in the food and beverage industries. It is worth mentioning that, although this alternative would considerably reduce the required amount of solvent, there is the problem of high energy consumption for the evaporation necessary to regenerate the organic solvent used, so another objective of the present invention will be to solve the problem of reuse. of the solvent used in this type of advanced extractions.

Another equally important objective of the present invention is to provide a system that allows the recovery of the polyphenols present whether there is solid waste or liquid waste, including effluents, from the aforementioned 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, that is, that they are separated from other compounds such as colloidal matter, proteins or carbohydrates.

Explanation of the invention

With the aim of solving the problems raised above, a system is proposed for the recovery of polyphenols from solid waste or solid waste and industrial liquid waste from the food and beverage sector, such as from the oil industry. olive and wine. It is understood that liquid waste also includes effluents, as these liquids come from an industrial plant.

The system for the recovery of polyphenols object of the invention is characterized by comprising:

- a microwave or ultrasonic assisted polyphenol extraction installation comprising an extraction chamber or tank suitable for receiving a batch of solid waste, provided with an ultrasonic or microwave source and at least a first inlet through the that a solvent suitable for the extraction treatment of polyphenols from volumes of solutions by ultrasound or microwave is introduced into the extraction chamber or tank;

- an intermediate tank whose inlet is arranged in communication with the outlet of the extraction installation, the volumetric capacity of the intermediate tank being suitable for the accumulation of at least a sufficient volume of solution or solutions treated in the extraction installation to allow continuous operation of a separation system that carries out a continuous process;

- a separation system connected to the outlet of the intermediate tank, formed by a microfiltration subsystem connected in series to an ultrafiltration subsystem which in turn is connected in series to a reverse osmosis subsystem, in which 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 wherein the reverse osmosis subsystem comprises a reverse osmosis membrane and an outlet for the reverse osmosis permeate;

- a reverse osmosis permeate reuse facility comprising a distribution tank connected to the reverse osmosis permeate outlet of the reverse osmosis subsystem, and further comprising two reuse conduits, in which the first reuse conduit connects a section of the outlet of the distribution tank with the interior of the extraction tank or chamber of the extraction installation for the reuse of the reverse osmosis permeate as a solvent, and in which the second reuse conduit connects a section of the outlet of the tank distribution with the interior of the intermediate tank for the reuse of the reverse osmosis permeate as a contribution 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 becoming clogged and reducing the soiling thereof;

- control means programmed to receive the transmembrane pressure value of the membrane microfiltration process at a moment or time interval and compare it with a pre-established membrane protection threshold value, and programmed to decide and control the introduction of the osmosis permeate inversely in the first reuse conduit, if the transmembrane pressure value received is less than said pre-established threshold value, or in the second reuse conduit, if the transmembrane pressure value received is equal to or greater than said pre-established threshold value.

The system object of the invention comprises a conduit or a mixing chamber provided with one or more inlets for the introduction of the available industrial liquid waste, arranged either at the inlet or at the outlet of the intermediate tank. Preferably, it is planned that the mixing of the liquid waste with the solid waste (the latter in the form of solutions treated with ultrasound or microwaves) is after the intermediate tank, when the intermediate tank is a settling tank, to maximize its capacity to separate the solid of the supernatant to be treated in the membranes after extraction. Therefore, in The system is arranged first with the extraction installation, followed by the intermediate tank (it can be a decanter) and then there are two alternatives: add only solid waste, mix the solid and liquid waste previously to the membrane train, or feed it separately (i.e. say that they mix in a drive).

When the transmembrane pressure value received by the control means is equal to or greater than said threshold value, the control means will activate and control the introduction of the reverse osmosis permeate into the second reuse conduit, and when said pressure value transmembrane is less than the threshold value, the control means will activate and control the introduction of the permeate into the first reuse conduit.

The system object of the invention allows carrying out a procedure that includes the operations of:

a) subjecting the solid waste, in batches, to a polyphenol extraction operation by adding a solvent and the action of ultrasound or microwaves to obtain treated volumes of solution;

b) introduce and retain in an intermediate tank one or more volumes of treated solution c) drive all or part of the content retained in the intermediate tank as feed to a continuous process that includes the serial operations of membrane microfiltration, ultrafiltration of the microfiltration membrane permeate and reverse osmosis membrane permeate ultrafiltration,

The procedure also includes reuse of the reverse osmosis permeate as a solvent in operation a) and as a contribution to the intermediate tank to increase the sedimentability of the solids present in the content retained in the intermediate tank and protect the membranes by preventing them from becoming clogged. and reduce their fouling. Said reuse of the reverse osmosis permeate is the result of an operation of comparing the transmembrane pressure value of the microfiltration process with a pre-established membrane protection threshold value, resulting in its reuse as a contribution to the intermediate tank when the aforementioned transmembrane pressure value is equal to or greater than the aforementioned threshold value, and as a solvent in operation a) when it is lower.

In the event that industrial liquid waste from the food and beverage sector is available, these liquid waste are introduced and retained in the intermediate tank, or are introduced downstream of the intermediate tank and driven as feed to the continuous microfiltration process by membrane, ultrafiltration of permeate membrane microfiltration and membrane reverse osmosis permeate ultrafiltration.

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

Advanced extraction, referred to here as ultrasonic or microwave assisted extraction, reduces extraction time and solvent needs compared to other alternatives on the market, such as direct membrane filtration or conventional extraction, while maximizing extraction performance. 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 could be applied) to maximize the recovery of polyphenols, regardless of the hydrophobicity of the compounds in the waste. 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 olive oil waste, these are mainly aimed at recovering water from the vegetation (liquid waste) and do not correspond to the same membrane treatment train of the procedure. In the system of the invention, a reverse osmosis operation is applied after the ultrafiltration operation, and not nanofiltration, in order to increase the recovery of polyphenols. This is because the inventors have observed that the MWCO (limiting molecular weight in English, also called threshold molecular weight) of some polyphenols, for example the MWCO of those in olive oil, is similar to the MWCO of the particle size of nanofiltration membranes, so if a nanofiltration membrane were installed, there would be some polyphenols that would remain in the retentate but others would pass into the permeate, limiting the percentage of recovery of polyphenols. Another feature worth highlighting is the membrane microfiltration that is carried out before membrane ultrafiltration, to minimize fouling of the ultrafiltration membrane and increase the useful life of the membranes.

It is noteworthy that the system object of the invention is indicated for the treatment of both liquid and solid matter, maximizing the recovery of polyphenols in a single system in which the procedure is carried out. The integration of a discontinuous process such as advanced ultrasonic or microwave extraction, which is carried out in batches, with a continuous one such as purification and concentration treatment by membranes, is resolved by the accumulation of volumes of solution treated by having been subjected to ultrasound or microwaves in the intermediate tank, which allows sufficient quantity to be available to ensure continuous feeding to the series operations carried out on the aforementioned membranes. In this way, it is established that the intermediate tank is maintained with a certain amount of liquid during the entire duration of the cycle carried out for the recovery of polyphenols.

The combination of microfiltration, ultrafiltration and reverse osmosis makes it possible to achieve an extract rich in polyphenols from the reverse osmosis retentate and to reuse the reverse osmosis permeate, which contains the organic solvent and is free of impurities, as a solvent for the operation. ) extraction, without the need for external evaporation steps for solvent recovery. Furthermore, 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 a sufficient amount of volumes of treated dissolution (second by-product) to ensure correct continuous operation of the series operations carried out on the membranes.

In addition to the above, the procedure carried out in the system object of the invention contemplates the reuse of the reverse osmosis permeate as a solvent in operation a), which makes it a more sustainable alternative and contributes to cost reduction. economical because they require less solvent to be supplied externally to carry out the extraction by ultrasound or microwaves. The initial solvent that is added in the beginning of the procedure to the 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 carried out using ultrasound or microwaves. With the reuse of the reverse osmosis permeate as a solvent, a mixture of ethanol and water will act as a solvent in the following extractions, thus reducing the initial ethanol contribution from the supply tank.

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

When choosing the membranes, it has been taken into account that the size of the ethanol molecule is greater than that of water, to make it possible for ethanol and not just water, as occurs in other groups of membranes of the state of the art. , crosses all the membranes reaching the reverse osmosis permeate. If instead of ethanol the use of another initial solvent analogous 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 procedure carried out in the system of the invention, it has been planned that the volumes of solution treated in the ultrasonic or microwave extraction are subjected to a decantation process before the microfiltration operation of the continuous process, to reduce the content of solids present at the entrance to the membrane train. This decantation can occur either in the extraction facility in which the polyphenol extraction operation is carried out, or before being introduced into the intermediate tank when subjected to a centrifugation operation to reduce the solids content prior to its introduction. , or in the intermediate tank as this tank is configured as a settling tank.

Related to the above, another aspect to take into account is that the procedure carried out in the system object of the invention solves one of the problems that can be generated when jointly applying an extraction with a train of membranes, specifically, the of the possible presence of solids in the stream coming from the extraction at the entrance of the membranes, which can lead to high fouling of the membranes, making their operability difficult as they become obstructed by said solids (closing some of the pores of the membranes). Depending on the specific characteristics of the solid and liquid industrial waste available at any given time, the planned sedimentation or decantation of the solid components present may not be sufficient to ensure that the stream reaching the membranes has a solids content compatible with the correct one. operation of the same, and for this reason, in these circumstances, the system object of the invention contemplates the reuse of the reverse osmosis permeate as a contribution to the intermediate tank to increase the sedimentability of the solids present in the contents of the intermediate tank and protect to the membranes, helping to extend their useful life.

According to a particular embodiment of the system object of the invention, a section of the outlet of the distribution tank is provided with a bifurcation by which said section is connected on one side to the first reuse conduit and on the other side to the second reuse conduit. reuse. The control means in this variant are programmed to act on the bifurcation and disable the connection with the second reuse conduit so that the section of the outlet of the distribution tank is only communicated with the second inlet to the extraction tank or chamber. the extraction installation, and if the real-time transmembrane pressure value is equal to or greater than the membrane protection threshold value, the control means are programmed to act on the bifurcation and only enable the connection with the second waste reuse conduit. so that the outlet section of the distribution tank is only connected to an inlet to the intermediate tank.

The membrane protection threshold value is between 5 and 1000 kPa, preferably between 50 and 300 kPa. A more restrictive threshold value, between 100 and 150 kPa, can also be considered. Thus, the transmembrane pressure in the microfiltration operation is monitored and in the event that it reaches or exceeds an established threshold value, the reverse osmosis permeate is sent to the intermediate tank. In any case, the threshold value that is finally established depends on the type of membrane and the manufacturer's recommendations.

In this way, in the procedure carried out in the system object of the invention, the transmembrane pressure of the second byproduct is measured at the entrance to the production system. microfiltration, and if it is high (equal or greater than the preset threshold value), the reverse osmosis permeate is diverted to the intermediate tank to avoid damage to the membranes. The measurement of transmembrane pressure has been chosen as it is an easier value to measure and because it allows better monitoring of the process than would be provided by measuring the solids content. The contribution of the reverse osmosis permeate to the intermediate tank causes the solids content of the supernatant to decrease and therefore, the stream of said supernatant (second by-product) that will be subjected to the microfiltration operation will not pose a risk to the integrity of the the membranes. This function is punctual and only in case of need, so in the rest of the cases, the reuse of the reverse osmosis permeate will be as a solvent for operation a) of extraction. In this way, a correct coupling is achieved between operation a) of extraction and the continuous operation carried out in the membrane train, allowing solvent losses and damage to the membranes to be avoided, providing a solution to the technical problem derived from combining the process. extraction from solid waste with the series process of microfiltration, ultrafiltration and reverse osmosis that does not receive only liquid waste, but a mixture of these with the solutions treated in operation a) of ultrasonic or microwave extraction. It also constitutes a solution for cases in which the liquid waste to be treated already has a high solids content.

Preferably, a tank is provided between the microfiltration membrane and the ultrafiltration membrane. Optionally, a tank can also be provided between the ultrafiltration membrane and the reverse osmosis membrane. Thus, in the event that a high transmembrane pressure is detected (from a value set as "high") that could damage the ultrafiltration membrane or the reverse osmosis membrane, the possibility of diverting the permeate from the osmosis is considered. reverse to one or more of these tanks prior to the ultrafiltration or reverse osmosis membranes.

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

It is also envisaged that the system object of the invention comprises a solvent supply tank (preferably ethanol) for the supply controlled by the control means of a quantity of solvent through an inlet to the extraction tank or chamber of the microwave or ultrasonic assisted polyphenol extraction facility.

Advantageously, the system object of the invention can comprise centrifugation means arranged between the extraction installation and the intermediate tank, to minimize the presence of solids in the stream that enters the intermediate tank. Alternatively, the intermediate tank or extraction tank (or chamber of the extraction installation) can be configured as a settling tank.

In the continuous process fed by the second by-product (volumes of treated solution accumulated in the intermediate tank), which can be for example the supernatant of the intermediate tank, first the stream of the second by-product is subjected to a microfiltration step, to eliminate the presence of solids, mainly colloidal matter that is retained, and to minimize fouling and clogging of the membranes of the following stages. The microfiltration permeate is treated in an ultrafiltration step to purify and concentrate the polyphenol-rich stream.

In relation to the parameters to be considered in the choice of membranes, preferably the membranes are hydrophobic, the pore size of the membrane of the ultrafiltration subsystem is between 5 and 10 kDa, necessary to purify the polyphenol stream and reduce the presence of proteins and carbohydrates, and the particle size of the reverse osmosis membrane is between 50 and 120 Da, to achieve a correct separation of the polyphenol extract and the solvent stream, thus maximizing the recovery of polyphenols and al At the same time, a high purity permeate is obtained, suitable for being directly used as a solvent in operation a) of extraction. Thus, in serial microfiltration, ultrafiltration and reverse osmosis operations, the membranes are not only configured for the successive separation of the permeate from colloidal matter, 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, remains in the successive permeates so that having finally crossed the reverse osmosis membrane, this permeate can be introduced into the extraction installation assisted by ultrasound or microwaves as a solvent.

Finally, it is anticipated that the system object of the invention comprises a tank of ethanol supply for the controlled supply by the control means of a quantity of ethanol through the first inlet to the extraction tank or chamber of the microwave or ultrasonic assisted polyphenol extraction facility.

Brief description of the drawings

To complement the description that is being made and in order to facilitate the understanding of the characteristics of the invention, this descriptive report is accompanied by a set of drawings in which, for illustrative and non-limiting purposes, the following has been represented:

Fig. 1 is a schematic view of a first embodiment of the polyphenol recovery system object of the invention in which the solid waste and industrial liquid waste from the food and beverage sector from which polyphenols are recovered have also been represented. , 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;

Fig. 2 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;

Fig. 3 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;

Fig. 4 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 provided through a pipeline between the extraction installation and the intermediate tank to be introduced into the intermediate tank; and

Fig. 5 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 provided through a pipeline between the extraction installation and the intermediate tank to be introduced into the intermediate tank.

Detailed description of the embodiment

In Figs. 1 to 5 shows a system 100 for the recovery of polyphenols from solid waste 92 and liquid industrial waste 93 from the food and beverage sector, such as those from the olive oil and wine industries. It is appreciated that the System 100 first comprises a polyphenol extraction facility 1 assisted by microwave or ultrasound, which in turn comprises a container or chamber suitable for receiving a batch of solid waste 92, provided with an ultrasound or microwave source 13. and a first and second inlet through which a solvent suitable for the extraction treatment of polyphenols from volumes of solutions by ultrasound or microwave is introduced into the extraction tank or chamber of the extraction installation. The first inlet is connected to a solvent supply tank 12 (preferably an ethanol tank) for the controlled supply by control means 70 of a quantity of ethanol to the container or chamber of the extraction installation 1. The second inlet, represented To the right of the first, it receives a mixture of water and solvent (preferably ethanol) reused as a solvent and which comes, as will be explained later, from a distribution tank 7.

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

Next, the treated solution volumes 10 are introduced and retained in an intermediate tank 3 whose volumetric capacity is suitable for the accumulation of at least a sufficient volume of solution or treated solutions in the extraction installation 1 to allow the continuous operation of a separation system that carries out a continuous process that includes the serial operations of membrane microfiltration, ultrafiltration of the microfiltration permeate 40 by membrane and reverse osmosis by membrane of the ultrafiltration permeate 50. From the intermediate tank 3 it is driven , for example, through a pump (not shown in the figures) all or part of its contents as feed to this continuous process. As the output of the treated solution volumes 10 from the extraction installation 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 during the time that the total operation cycle lasts. the extractor installation 1, and not only when the extractor installation 1 is downloaded.

As indicated, the system 100 allows the recovery of polyphenols from solid waste 92 and, in addition, also from liquid waste 93. The liquid waste 93 can be introduced into the system 100 in any of the following locations:

- downstream of the intermediate tank 3, as is the case of the systems represented in Figs. 1,2 and 3; either

- before the intermediate tank 3 to be introduced and retained therein, as is the case of the systems 100 represented in Figs. 4 and 5.

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

In Figs. 1 to 5 it can be seen how a separation system is connected to the outlet of the intermediate tank 3, said separation system being formed by a microfiltration subsystem 42 connected in series to 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 connected in turn to the inlet of the ultrafiltration subsystem 52. The ultrafiltration subsystem 52 It 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 inlet of the reverse osmosis subsystem 62. The reverse osmosis subsystem 62 It comprises a reverse osmosis membrane 6 with a particle size between 50 and 120 Da and an outlet for the reverse osmosis permeate 60. Preferably, the described separation system comprises a tank between the microfiltration membrane 4 and the filtration membrane 5. ultrafiltration, and another tank between the ultrafiltration membrane 5 and the reverse osmosis membrane 6. From each subsystem there are two outputs, the first known as permeate (40, 50 and 60) and the second known as rejection (41, 51 and 61).

The reason and configuration of the membrane train 4, 5, and 6 is as follows. Firstly, the stream at the outlet of the intermediate tank 3 is subjected to a microfiltration stage, to eliminate the presence of solids, mainly colloidal matter 41 that is retained constituting the rejection stream, and to minimize fouling and clogging of membranes 4, 5 and 6 of the following stages 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 10 KDa, necessary to purify the polyphenol stream and reduce the presence of proteins and carbohydrates in the ultrafiltration permeate 50. Rejection from ultrafiltration contains polysaccharides 51 in a high concentration and after a brief evaporation, it can be used as food for animals. For its part, the permeate from ultrafiltration 50 is finally subjected to a reverse osmosis process to maximize recovery and concentrate the stream with polyphenols 61. The stream rich in polyphenols 61 retained in reverse osmosis can be used in the system facilities themselves. 100 to produce products enriched with antioxidants or to be sold to external customers. Reverse osmosis makes it possible to achieve a permeate stream 60 of high purity, said reverse osmosis permeate 60 being formed by a mixture of water and solvent (preferably ethanol or similar compound), for which the particle size of the osmosis membrane 6 reverse osmosis permeate 60).

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

As seen in Figs. 1 to 5, system 100 comprises a reverse osmosis permeate reuse facility 60 which in turn comprises:

- a distribution tank 7 connected to the reverse osmosis permeate outlet 60 of the reverse osmosis subsystem 62;

- a first reuse conduit 71 that connects a section of the outlet of the distribution tank 7 with the interior of the container or chamber of the extraction installation 1 for the reuse of the reverse osmosis permeate 60 as a solvent in the ultrasonic extraction operation or by microwave;

- a second reuse conduit 72 that connects a section of the outlet of the distribution tank 7 with the interior of the intermediate tank 3 for the reuse of the reverse osmosis permeate 60 as a contribution to the intermediate tank 3 to reduce the concentration of solids and protect to membranes 4, 5 and 6, avoiding fouling and obstruction;

- control means 70 programmed to receive the transmembrane pressure value of the membrane microfiltration process 4 at a moment or time interval, and decide and control the introduction of the osmosis permeate reverse 60 in the first reuse conduit 71 or in the second reuse conduit 72 according to the result of an operation of comparing the transmembrane pressure value of the microfiltration process at a moment or time interval, with a pre-established protection threshold value of membranes, resulting in the introduction of the reverse osmosis permeate 60 into the second reuse conduit 72 when said transmembrane pressure value is equal to or greater than said threshold value, and into the first reuse conduit 71 when said pressure value transmembrane is less than the threshold value.

In Figs. 1 to 5 it can be seen how a conduction section at 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 conduit 71 and on the other side to the second reuse conduit 72 The control means 70 are programmed to act on the branch 73 and disable the connection with the second reuse conduit 72 so that the section of the outlet of the distribution tank 7 is only communicated with the second entrance to the container or chamber. the extraction installation 1, and if the real-time transmembrane pressure value 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 enable the connection with the second duct of reuse 72 so that the section of the outlet of the distribution tank 7 is only connected with an inlet to the intermediate tank 3.

The membrane protection threshold value can be between 5 and 1000 kPa, although preferably, it has been established as a value between 50 and 300 kPa, and in some cases a more restrictive value may be contemplated, such as one selected and included between 100 and 150 kPa. In any case, the threshold value that is finally established depends on the type of membrane and the manufacturer's recommendations. Thus, the transmembrane pressure is monitored or controlled in the microfiltration stage, for example by means of the meter 74 or similar means, and in the case of reaching values equal to or greater than those in the range of the protection threshold value (for example established 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 reduce the concentration of solids at the entrance of the membrane microfiltration 4. In this way, although the main function of the control means 70 is the recovery of the solvent (the permeate resulting from the reverse osmosis 60) to reuse it in the extraction operation, the second function will be priority in case of necessity.

The system 100 represented in Fig. 3 contemplates 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 stream that enters the intermediate tank 3. The systems 100 depicted in Figs. 1 and 4 do not have said centrifugation means, but with the purpose of minimizing the presence of solids in the stream that will later pass to the membrane separation system, the extraction tank or chamber of the extraction installation 1 is formed as a tank decanter, at the bottom of which the suspended solid matter settles and the supernatant from the extractor tank goes on to feed the intermediate tank 3. However, in Figs. 2 and 5, it is the buffer tank 3 of system 100 that is configured as a settling tank.

In summary, the system 100 previously described above allows carrying out the procedure for the recovery of polyphenols from solid waste 92 and liquid waste 93 from the food and beverage sector, which includes the operations of:

a) subjecting the solid waste 92, in batches, to a polyphenol extraction operation by adding a solvent and the action of an ultrasound or microwave source 13 to obtain treated solution volumes 10;

b) introduce and retain in the intermediate tank 3 one or more volumes of treated solution 10;

c) drive all or part of the content retained in the intermediate tank 3 as feed to the continuous process that includes the serial operations of microfiltration by membrane 4, ultrafiltration of the microfiltration permeate 40 by membrane 5 and reverse osmosis by membrane 6 of the 50 ultrafiltration permeate, 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 and 6 preventing them from becoming clogged and reducing their contamination.

As has been explained in relation to system 100, and specifically in reference to the control means 70, the reuse of the reverse osmosis permeate 60 as a solvent in operation a) or as a contribution to the intermediate tank 3 is the result of a operation of comparing the transmembrane pressure value of the microfiltration process with a value pre-established membrane protection threshold (preferably between 50 and 300 kPa), resulting in reuse as a contribution to the intermediate tank 3 when the aforementioned transmembrane pressure value is equal to or greater than the aforementioned threshold value, and as a solvent in operation a) when be less.

As mentioned previously, the introduction of the liquid waste 93 into the system 100 to be treated and recover the polyphenols from them can be done at different points, for example introducing them before the intermediate tank 3, joining them before with the volumes of treated solution 10 from the extraction installation 1, or that reach the intermediate tank 3 independently of said volumes of treated solution 10, or that are introduced into the system 100 downstream of the intermediate tank 3, at the entrance of the microfiltration subsystem 42, mixed or not with the stream coming from the outlet of intermediate tank 3.

Claims (11)

1. A 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: - a microwave or ultrasonic assisted polyphenol extraction installation (1) that comprises an extraction chamber or tank suitable for receiving a batch of solid waste (92), provided with an ultrasonic or microwave source (13) and at least a first inlet through which a solvent suitable for the extraction treatment of polyphenols from volumes of solutions by ultrasound or microwave is introduced into the extraction chamber or 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 a sufficient volume of solution or solutions treated in the extraction installation (1) to allow the continuous operation of a separation system that carries out a continuous process; - a separation system connected to the outlet of the intermediate tank (3), formed by a microfiltration subsystem (42) connected in series to an ultrafiltration subsystem (52) which in turn is 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 ultrafiltration subsystem (52), in which the subsystem The ultrafiltration system (52) comprises an ultrafiltration membrane (5) and an outlet for the ultrafiltration permeate (50) connected to the inlet of the reverse osmosis subsystem (62), and wherein the reverse osmosis subsystem (62) comprises a reverse osmosis membrane (6) and an outlet for the reverse osmosis permeate (60); - a reverse osmosis permeate reuse facility (60) comprising a distribution tank (7) connected to the reverse osmosis permeate outlet (60) of the reverse osmosis subsystem (62), and further comprising two reuse (71, 72), the first reuse conduit (71) being the one that connects a section of the outlet of the distribution tank (7) with the interior of the extraction tank or chamber of the extraction installation (1) for reuse of the reverse osmosis permeate (60) as a solvent, and the second reuse conduit (72) which connects a section of the outlet of the distribution tank (7) with the interior of the intermediate tank (3) for the reuse of the permeate from reverse osmosis (60) as a contribution to the intermediate tank (3); - control means (70) programmed to receive the transmembrane pressure value of the membrane microfiltration process (4) at a moment or time interval and compare it with a pre-established membrane protection threshold value, and programmed to decide and control introducing the reverse osmosis permeate (60) into the first reuse conduit (71) or into the second reuse conduit (72). 2. The system (100) for the recovery of polyphenols according to claim 1, characterized in that a section of the outlet of the distribution tank (7) is provided with a bifurcation (73) by which it is connected on one side to the first conduit. of reuse (71) and on the other hand to the second reuse conduit (72), and because the control means (70) are programmed to act on the bifurcation (73) and disable the connection with the second reuse conduit ( 72) so that the outlet section of the distribution tank (7) is only communicated with the second entrance to the extraction tank or chamber of the extraction installation (1), and the control means (70) are programmed to act on the bifurcation (73) and only enable the connection with the second reuse conduit (72) so that the section of the outlet of the distribution tank (7) is only connected with an inlet to the intermediate tank (3). 3. The system (100) for the recovery of polyphenols according to claim 1 or 2, characterized in that the membrane protection threshold value is between 5 and 1000 kPa. 4. The system (100) for the recovery of polyphenols according to claim 3, characterized in that the membrane protection threshold value is between 50 and 300 kPa. 5. The system (100) for the recovery of polyphenols according to claim 4, characterized in that the membrane protection threshold value is between 100 and 150 kPa. 6. The system (100) for the recovery of polyphenols according to any one of claims 1 to 5, characterized in that it comprises centrifugation means arranged between the extraction installation (1) and the intermediate tank (3). 7. The system (100) for the recovery of polyphenols according to any one of claims 1 to 5, characterized in that at least the intermediate tank (3) or the extraction tank or chamber of the extraction installation (1) is formed as a tank decanter. 8. The system (100) for the recovery of polyphenols according to any one of claims 1 to 7, characterized in that the pore size of the membrane (5) of the ultrafiltration subsystem (52) is between 5 and 10 kDa and The particle size of the reverse osmosis membrane (6) is between 50 and 120 Da. 9. The system (100) for the recovery of polyphenols according to any one of claims 1 to 8, characterized in that the microfiltration membrane (4) of the microfiltration subsystem (42), the ultrafiltration membrane (5) of the ultrafiltration (52) and the reverse osmosis membrane (6) of the reverse osmosis subsystem (62) are hydrophobic membranes. 10. The system (100) for the recovery of polyphenols according to any one of claims 1 to 9, characterized in that it comprises an ethanol supply tank (12) for the controlled supply by the control means (70) of a quantity of ethanol through the first inlet to the extraction tank or chamber of the polyphenol extraction facility (1) assisted by microwave or ultrasound. 11. The system (100) for the recovery of polyphenols according to any one of claims 1 to 10, characterized in that it comprises a conduit or a mixing chamber provided with one or more inlets (22) for the introduction of liquid waste (93). available industrial tanks, at the entrance or exit of the intermediate tank (3).