ES2634333B1 - PROCEDURE FOR THE TREATMENT OF WASTE AND OBTAINING SUBPRODUCTS OF ALMAZARAS - Google Patents

Abstract

Procedure for the treatment of waste and obtaining by-products from oil mills. # The present invention relates to a process for treating waste from oil mills and obtaining by-products of industrial interest comprising a step of mixing solid and liquid waste that contributes to improve the extractive process, an extraction stage and a solid-liquid separation stage. In this way, a solution is offered to the problem posed by by-products or solid and liquid waste from the oil mills, allowing the recovery of polluting waste from the spills.

Description

PROCEDURE FOR THE TREATMENT OF WASTE AND OBTAINING SUBPRODUCTS OF ALMAZARAS

SECTOR OF THE TECHNIQUE

The present invention can be included in the field of industrial waste treatment in industries that generate waste containing mixtures of solid and liquid elements such as the agro-food industry of olive oil extraction. Specifically, the present invention seeks to solve the problem posed by solid and liquid by-products or residues of oil mills.

STATE OF THE TECHNIQUE

Waste generated in the oil mills

Olive oil production has increased significantly during the last decades. As an unwanted parallel effect, the amounts of waste derived from the olive oil production process have been significantly increased, especially due to the change in traditional discontinuous press technology by the continuous systems currently used, based on centrifugation processes

The production of table olives and olive oil grows year after year, and similarly the waste generated in the process. Approximately 30 million cubic meters (m3) of waste from the olive industry is processed annually. A modern mill of average size today generates between 10 and 15 m3 of wastewater daily, which in Spain alone accounts for more than 9 million m3 of these wastewater annually, which represents a huge volume of discharge of these effluents highly polluting, as well as drinking water consumption, in addition to approximately 800 kg of solid waste for each ton of processed olive.

The main residual liquid effluents that are generated in the oil mills are constituted by the alpechin and the washing waters of the olive, as well as the oil washing in the centrifuges, the bucket of the patio and punctually of the hopper. On the other hand, a solid residue called alpeorujo is generated, with a humidity of 60-75%, which hinders its further treatment. These residues have a series of characteristics that make their treatment by conventional physicochemical means extremely difficult.

The presence of recalcitrant phytotoxic contaminants - such as tannins, phenolic compounds, organic acids, long chain fatty acids and organohalogenated compounds - makes these effluents highly resistant to their microbial degradation and therefore inhibits the efficiency of biological treatments. In addition, its physical-chemical composition is very variable, since it depends on several factors such as the extraction process used in the production of the oil, edaphoclimatic and cultivation parameters, as well as the type, quality and maturity of the processed olives .

These residues are characterized by their strong odor, acidity, intense dark violet color, considerable salinity reflected by high values of electrical conductivity, as well as a high polluting power of organic origin. Added to this are difficulties such as the small size and geographical dispersion of the oil mills, as well as the seasonality of olive oil production, which further complicates their treatment.

The direct discharge of these wastewater and solid waste to public channels is currently prohibited, since they cause severe polluting consequences, and cannot be reused directly for irrigation or as fertilizer, respectively. Numerous studies have reported that the discharge of these effluents results in annoying odors in the surroundings, phytotoxic effects on plant growth, alteration of the nutrient balance of the soil, contamination of water bodies and impediment of self-purification processes , as well as dramatic impacts on aquatic fauna and in this is your ecological.

Solutions for the treatment of mill waste.

In countries like Spain, the generally adopted solution has been the construction of artificial rafts for the natural evaporation of waste. Over the years this measure proved inefficient, since in the rafts this residue is concentrated, increasing its pollution power year after year. In addition, due to the limited capacity of the rafts, when they are filled, the need arises to build new ones, causing the following problems in the sector, such as the increase in the occupied area, overflow, sanctions and stoppage of activity, a brake on

implementation of quality systems, air pollution, leaks to the subsoil contaminating the ground and groundwater, bad odors, insect pests, as well as problems in areas with high rainfall.

The technology of obtaining olive oil in continuous is based on centrifugation processes of three or two phases. In the three-phase system, a residual discharge commonly called alpechin is obtained, which includes the olive vegetation water, the addition and washing water and a variable percentage of solid, and a solid residue (pomace). In the two-phase procedure, called the ecological system And widely implemented in recent years, the decanters used have only two outputs, one through which the oil comes out, with some moisture, and on the other the solid waste, called "alpeorujo ", with 55-70% humidity approximately. Subsequently, the oil is washed in the vertical centrifuge, while the pomace serves as the basis for the extractor industry.

However, the problem regarding these wastes has not yet been solved. The effluents from the two-phase olive oil production system still have significantly high values of organic matter, detected by measuring the biological oxygen demand (DBDs) and the chemical oxygen demand (DQD), between 0.8 and 2.2 gIL in the residual washing water of the olives and between 4 and even 18 gIL in the effluent of the centrifugation process. On the other hand, the organic load of the alpeorujo is up to more than ten times higher.

Currently working on the search for viable solutions from the economic point of view and applicable at the industrial level. So far, a range of processes have been proposed to solve the management and treatment of these wastes, recently developing new technologies to reduce their contamination by physical, chemical and biological procedures, as well as combinations of them. [Sánchez, S., Martínez, M.E., Espejo, M.T., Pacheco, R., Espinola, F., Hodaifa, G., 2001. Mixotrophic culture of ChJorella pyrenoidosa with ofive-mill wastewater as the nutrient medium. Journal of Applied Phycology 13 (5), pp. 443-449] made a first attempt to use wastewater from the three-phase centrifugation process (alpechin) in the production of the Chlorella Pyrenoidosa microalgae biomass. Subsequently, [Hodaifa, G., Eugenia-Sánchez, M., Sánchez, S., 2008. Use of industrial wastewater from olive-oil extraction for biomass production of Scenedesmus obliquus. Bioresource Technology 99, pp. 1111-1117] studied the possible use of water

residuals of the olive industry that operate with the three-phase process in the

Biomass production of Scenedesmus Obliquus microalgae. Among the proposed solutions, the biological processes have shown a low effectiveness and therefore have not been escalated at an industrial level, due to the resistance of these effluents to biological degradation [Taccari, M., Ciani, M., 2011. Use of Pichia fermentans and Gandida sp. Strains for the bioJogical trealmen! of stored olive mili wastewater. Biotechnoly Letters 33, pp. 2385-2390].

Among other proposed treatments are natural or forced evaporation processes [Paraskeva P., Diamadopoulos E., 2006. Technologies for olive mili wastewater (OMW) treatment: A review. Journal of Chemical Technology and Biotechnology 81, pp. 1475-1485], treatments with silt and clays [Aktas, E. S., Imre, S., Esroy, L., 2001. Characterization and lime treatment of olive mili wastewater. Water Research 35, pp. 2336-2340], composting lPapadimitriou, E. K., Chatjipavlidis, l., Balis, C., 1997. Application of composting to olive mili wastewater treatment. Environmental Technology 18 (1), pp. 101-107], coagulation-f1oculation [Sarika, R., Kalogerakis, N., Mantzavinos,

D., 2005. Treatment of olive mili effluents. Part 11. Complete removal of solids by direct flocculation with poly-electrolytes. Environmental International 31, pp. 297-304] And electrocoagulation [Tezcan Ün, Ü., Ugur, S., Koparal, A. S., Ogütveren, Ü. B., 2006. Electrocoagulation or, olive mili wastewaters. Separation and Purification Technology, 52 (1), pp 136-141].

However, the complexity, low efficiency and / or high implementation and operation costs have prevented the transfer of these treatments at the industrial level.

Valorization of mill waste

Many of the processes proposed for the treatment of waste from the olive industry are too expensive, and this sector, made up of small factories, is not willing to bear these high costs. However, such residues can be a very important and potentially economically viable source of natural antioxidants (polyphenols). Only 2% of the total phenolic content of the olives is transferred to the oil phase, with the greatest amount lost in the derived waste. Polyphenolic compounds have excellent antioxidant, antimicrobial and anticarcinogenic properties, favoring the elimination of free radicals in cells and providing protection against oxidative stress in biomolecules such as proteins, lipids and AON. Other polyphenolic compounds with very important antioxidant properties present in the residual residues of the olive oil industry are vanyl, caffeic, p-cumaric, procatechinic, oleic and maslinic acid, oleuropein, as well as tirasol, aglycone, luteolin and ligstroside, among others.

To date, these compounds, highly demanded by the agri-food, cosmetic, pharmaceutical and biotechnology sectors, have been synthesized by chemical processes, which contributes to further raising their price in the market.

In addition, if the polyphenolic compounds remain in these residues without being treated, they oxidize and / or gradually poly me, making these effluents highly phytotoxic and recalcitrant to biological degradation. Therefore, the recovery of the polyphenolic fraction can provide not only economic benefits, but also reduce toxicity to favor further treatment and discharge.

In the three-phase olive oil extraction system, approximately a pomace production between 60 -75% and 25 -30% of alpechín is obtained. The pomace contains 25 -35% moisture, 8 -10% oil and up to 1.5% by weight of polyphenolic compounds, this percentage being around 0.4-0.7% in the alpechin. In the two-phase extraction system, the alpeorujo yield is 70 -80%, containing 55 -70% moisture, up to 6% oil and approximately 0.4% polyphenolic compounds, while these percentages are lower in more 50% in the oil wash water. Some oil mills are equipped with olive bone separation systems, either before the extraction process or after the alpeorujo or pomace. Usually, the alpeorujo contains between 10-20% by weight of olive bone, depending on the variety of olive and the light size of the sorter or sieve used.

Several methods have been proposed to date for the recovery of polyphenolic compounds present in these wastewater, such as solvent extraction [Bertin, L., Ferri, F., Scoma, A., Marchetti, L., Fava, F., 2011. Recovery of high added value natural polyphenols from actual olive mili wastewater through salid phase extraction. Chemical Engineering Journal171 (3), pp. 1287-1293]. Our Research Group, in preliminary tests with two-phase centrifugal wastewater, has detected, by extraction with different solvents (ethyl acetate, hexane, ethanol) and gas chromatography coupled to mass spectrometry, levels

significant concentration mainly of thiol and hydroxytyrosol, as well as 3,4-dihydroxyphenyl glycol, pyrocatechol, oleuropein and oleic acid. Other proposed methods are adsorption with resins, extraction with supercritical fluids, the use of microparticles and bioflitters, cloud point extraction and ultrasonic assisted extraction [Víctor-Ortega, M.o., Ochando-Pulido, J.M., Martínez-Férez, 2016.

Performance and modeling of continuous ion exchange processes for phenols recovery from olive mili wastewater. Process Safety and Environment Protection 100, 242-251].

However, the high costs and / or low efficiency of most of these proposals has prevented its definitive industrial escalation. Among them, the liquid-liquid extraction with solvents seems a priori to the simplest operation and scaling in the small mills existing in the countries of the Mediterranean Basin. However, it has the disadvantage of the use of organic solvents, which in addition to being very expensive can generate additional environmental problems and safety problems and complicated recovery for reuse. In this sense, the patent ES 2282027 81 describes a process for the industrial obtaining of oleanolic and maslinic acid extract from solid mill products, for use as natural products in veterinary medicine. For its part, the patent ES 2291111 81 describes a method of using biophenols from mill waste by selective solvent extraction.

Solutions for waste disposal and utilization that use filtration

US 6361803 81 describes a method for the extraction of antioxidant compositions from olives, olive pulp, olive oil, and residual water from the olive oil production process, by means of a solid matrix to trap antioxidant components, whose subsequent solvent washing Organic polar would drag the antioxidant components. EP patent application 1369407 A 1 describes a method for the extraction of hydroxytyrosol from olive by-products, by chromatographic separation methods in aqueous extracts with ion exchange resins and polymeric adsorbents selected according to polarity and molecular size, resulting in the isolation of a single polyphenolic compound, for use in agri-food applications.

In this regard, membrane technology, which comprises microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (01), can offer a number of advantages compared to conventional separation processes, erecting it in a very promising technology for the purpose of recovering the polyphenolic fraction contained in the wastewater of the oil industry and the remediation of these effluents.

Among the important advantages of membrane technology we can highlight that it is a green and clean technology since it does not involve the use of chemical reagents, such as solvents, to achieve separation and concentration; its lower capital and energy consumption costs than most conventional separation processes, but still guaranteeing a high purification capacity, selectivity and recovery factor; and also easy industrial scaling by virtue of its modular nature, as well as its simple design and operation, and low maintenance requirements. In addition, the membrane processes can be projected for the recovery of specific compounds, by appropriate selection of the membrane material and suitable pore size, and for this purpose they can also be superficially charged depending on the pH of the solution, adding this way to the exclusion by impediment is rich a selectivity factor by effect of electrostatic charge very relevant.

A process for the reduction of the high organic load of the three-phase alpechin was proposed by [Borsani, R., Ferrando, 8., 1996. Ultrafiltration plant for olive vegetation waters by polymeric membrane batteries. Desalination 108, 281-286], consisting of a first stage of removal of suspended solids and oil, tangential ultrafiltration (polysulfone membrane of cut size of 30 kDa) and finally a double stage biological treatment, achieving a mean reduction in the Biological oxygen demand (0805) and chemical oxygen demand of 65 -70% (000). Another process of treatment of the three-phase alpechin [Turano, E., Curcio, S., De Paola, M.G., Calabró, V., lorio, G., 2002. An integraled cenlrifugalionullrafiltration system in the trealment of olive mili waslewater. J. Membr. Sci. 206, 519531] consists of an integrated centrifugation system - for the reduction of suspended solids - followed by ultrafiltration (17 kDa polysulfone membrane), reaching up to 80% and 90% overall reduction of solids concentration in suspension and 000, respectively. Some preliminary studies with membranes for the recovery of low molecular weight polyphenolic compounds have already been

proposed: [Cassano, A., Conidi, C., Giorno, L., Drioli, E., 2013. Fractionation ofolive mili wastewaters by membrane separation techniques. J. Hazard Mater. 248, 185-193], [Garcia-Castello, E., Cassano, A., Criscuoli, A., Canidi, C., Drioli, E., 2010. Recovery and concentration of polypheno / s (rom olive mili wastewaters by integrated membrane

system. Water Res. 44, 3883--3892], [Canidi, C., Mazzei, R., Cassano, A., Giorno, L.,

2014. Integrated membrane system for the production of phytotherapics from olive mili wastewaters. J. Membr. SeL 454, 322-329), Paraskeva, CA, Papadakis, V.G., Tsarouchi, E., Kanellopoulou, D.G., Koutsoukos, P.G., 2007. Membrane processing for olivemill wastewater fractionation. Desalination 213, 218-229]. As a counterpoint, both processes showed a rapid and irreversible clogging of the membranes, which causes them to decrease their productivity and therefore seriously compromise the economic viability of the process.

In patent applications EP 1773721 81 and WO 2008/067976 A1, the recovery of chemical compounds from the wastewater of the oil industry is proposed through a pH adjustment step followed by enzymatic hydrolysis, separation of particles and suspended solids to obtain a clarified liquid product, and finally the treatment thereof by microfiltration (preferably with 23-channel ceramic membranes, pore size between 0.1-1.4 ~ m), ultrafiltration (preferably with polymeric polysulfone membranes, cellulose acetate regenerated or polyethersulfone-polyamide, spiral, of molecular size between 1 -20 kDa), nanofiltration (preferably with polymeric membranes cutting size between 150 and 250 Da, in spiral configuration) and reverse osmosis (preferably with polymeric membranes of composite polyamide, high saline rejection, in spiral configuration), resulting in a retained phase rich in polyphenols and water purified as permeate.

The application EP 2044848 A 1 describes a process of treatment of the residual water of vegetation of the alpeorujo of two phases, to recover a polyphenolic concentrate and purified water by means of mechanical separation processes combined with membranes. The proposed process includes de-humidification of the alpeorujo by horizontal centrifugation (until reducing the humidity to 40 -55%) and extraction of the residual oil with organic solvents (hexane), after which additives and / or flocculants are added to facilitate the separation of the solid phase from the liquid by sedimentation, horizontal and / or vertical centrifugation and filtration, and finally

ultrafiltration (between 50 and 60 OC) and nanofiltration, all of them finished in diafiltration, and finally biological oxidation.

EP 2338500 A 1 proposes a process for obtaining a concentrated solution or powder consisting of different biologically active compounds (such as oleuropein, hydroxyrosol, verbacoside and anthocyanin pigments) from residues of the olive industry, in particular leaves and pruning residues, olive pulp and pomace, by integrating simple cold or hot or pneumatic extraction (preferably with hydro-alcoholic solutions, between 60 and 95 OC), followed by separation by microfiltration membranes (polymeric membranes of polysulfone, regenerated cellulose acetate or nylon in spiral configuration, or alumina tubular ceramics internally covered with zirconia or titanium dioxide, pore size between 0.1-3! -1m, with between 8 and 85 channels, operating temperature between 45 and 50 "e, pressure between 5 and 6 bar), ultrafiltration (preferably with spiral membranes, with a cut size between 0.5 -50 kDa), nanofiltration (size of cut between 150 and 250 Da, in spiral configuration) and reverse osmosis (in spiral configuration, of high or low salinity, preferably a maximum of 35 bar of operating pressure and up to 60 "e of temperature, with spacers of light size between 0 , 51 -0.97 mm), finally completed with a stage of refinement of the concentrates of the UF and NF stages by chromatographic resins

EP 2526785 A 1 describes a process for obtaining an extract rich in biologically active compounds of high molecular weight (> 500 Da) from the vegetation water and the olive mill pomace. The method combines physical-chemical and enzymatic pretreatment methods, microfiltration membrane technology (tubular ceramic pore size membranes between 0.1-1.4 IJm, with between 8 and 85 channels, operating temperature between 45 and 50 oC , pressure between 5 and 6 bar) and finally evaporation under vacuum, obtaining an extract characterized by a composition and specific properties for its application in the fields of the cosmetic, food and phytotherapy industries.

The patent ES 2277490 B 1 describes a process of industrialization of fresh alpeorujo by dehydration by centrifugation (between 35 and 45 "e for 40-60 minutes), from which the liquid fraction is centrifuged to separate solids and obtain a raw alpeorujo for its subject to centrifugation, biological treatment, alcoholic fermentation and filtration, and finally it is concentrated by means of a multi-effect vacuum evaporator (85 CC), obtaining a concentrate for multiple applications, and on the other hand condensed water that is subjected to a volatile scrubber column to separate the alcohol from the water, which will finally be purified by treatment columns.

In another patent, ES 2374 675 81, a device and method for the treatment and use of by-products of olive oil (alpeorujo or pomace), which comprises a preheating (between 100 and 200 oC for a maximum of 180, is described) minutes) of these and subsequent introduction into a reactor for direct heating with water vapor (pressure between 3 and 11 bar) and / or indirectly through a heating wall, and extraction of the volatile phase by condensation, and then effect a separation in a three-phase horizontal centrifuge.

In WO 2006/005986 A 1 a process for obtaining a concentrate in oleic polyphenols of solid or semi-solid sub-products of oil mills using a polar solvent is detailed (maximum temperature 85 oC for 3 to 5 hours, by-product / solvent ratio of 1/3 to 1/30) and enzymatic hydrolysis (with esterase and [3glucosidase, temperature between 50 and 60 'C, pH between 4 and 6.5), followed by the extraction of polyphenols from said mixture and subsequent concentrate of the solution by ultrafiltration (pore size between 0.01-0.1 IJm) and nanofiltration (hollow fiber or spirals, pore size between 1-10 nm) and finally vacuum distillation and spray-dry drying (maximum temperature 70 OC).

WO 2007/013032 A2 proposes a process for obtaining a concentrate rich in hydroxytyrosol from the residues and solid by-products of the olive grove, through an initial stage of extraction preferably with hydroalcoholic mixtures, followed by another subsequent stage of fluid extraction supercritical (with supercritical C02 at a temperature between 30 and 80 oC and pressure between 8 and 20 MPa), combined with nanofiltration (average membrane pore size of 300 Da, operating pressure between 1.0 -1.5 MPa) and reverse osmosis ( 4.0 -6.0 MPa), individually or integrally, and finally a spray drying, lyophilization or evaporation stage.

Therefore, the need to find more efficient and sustainable solutions for the treatment of these effluents is urgent, taking into account the increasingly demanding legislation on wastewater and wastewater treatment. In all the inventions described previously, the addition of an external current (solvent) is proposed, which implies the generation of a new residual current. On the contrary, no additional residual current is generated with the present invention, since it is the residual currents themselves generated in the mill that are mixed together.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a process for the treatment of waste from oil mills that allows to obtain by-products of industrial interest with high added value. This procedure is simple, safe and efficient, energy efficient and therefore economically, uses clean technologies considered "green", avoiding at all times the introduction of reagents in the process.

More specifically, the present invention relates to a process for treating waste from oil mills comprising a first stage of mixing solid and liquid waste, after which a liquid-solid extraction stage of compounds of interest is carried out, in that the extractant phase is water; then proceeding to a solid-liquid separation (Sfl) process, from which a solid and a liquid phase are obtained which in turn is composed of an aqueous phase highly enriched in compounds of interest (mainly polyphenolic compounds), plus a oil phase composed of residual olive oil.

The proposed procedure avoids the introduction of additional streams or reagents in the process, reusing the own by-product streams of the production process to obtain a stream rich in antioxidant compounds of high added value, as well as a stream with a minimized organic load for reuse in irrigation or discharge, devoid of the high organic load of the starting waste.

Unlike the inventions cited in the previous section, the present invention allows to carry out the treatment of waste and obtain its use without introducing any additional current in the process, but by reusing the own by-product streams of the productive process to obtain a current rich in compounds high value-added antioxidants (with a profile in synergistic heterogeneous polyphenolic compounds) and a stream with a reduced organic load for reuse in irrigation or spillage, in which a heterogeneous concentrate rich in hydroxytyrosol is obtained that has highly antioxidant properties,

antimicrobial, anti-inflammatory and anticarcinogenic, which allow to compensate for the cost of the treatment process of these effluents.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1.-Diagram depicting the three stages comprising the process of the invention. (E1) represents the mixing stage of solid (RS) and liquid (RL) waste. (E2) represents the liquid-solid extraction stage of compounds, performed in a mixing tank, (T). (E3) represents the solid-liquid separation stage that gives rise to industrially usable by-products in solid phase (FS) and liquid phase (FL).

Figure 2.-Diagram depicting the third stage of the process of the invention together with an additional stage (S) of separation of the aqueous (FL 1) and oil (FL2) phases.

Figure 3.-Diagram representing the third stage of the process of the invention together with an additional stage (8) of separation of the aqueous (FL 1) and oily (FL2) phases and a final nanofiltration stage that gives rise to by-products ( P) with a high content of polythene and a liquid residue (R) with minimized polyenolic load.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The concept of "waste from oil mills" encompasses waste produced by obtaining olive oil and the production of table olives. By way of example, "pomace residues" are the pomace, the alpeorujo, the olive bone, the alpechin, the olive washing water, the oil washing water and the brine. Among the residues of the oil mills, for the purposes of the present invention, solid waste and liquid waste are distinguished. Liquid uresiduos shall be considered: two "those whose moisture content exceeds 80%, such as oil or olive wash water, brine or alpechin; while the term" solid waste "refers to those whose content in Water is equal to less than 80%, such as pomace, alpeorujo, or olive bone.

The term "comprises", which can also be interpreted as "consists of", and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention.

Invention Procedure

In a first aspect, the present invention relates to a method of extracting waste from oil mills, hereinafter "method of the invention" (Figure 1), which comprises the following steps:

Mixture (E1) of solid waste (RS) and liquid waste (RL) from

oil mills

Liquid-solid extraction (E2) of compounds, characterized in that the phase

extractant comprises at least 5% water, preferably more than one

15% water, more preferably between 20 and 30% water, and even more

preferably around 25% water.

Solid-liquid separation (E3) (SIL), by which the resulting product is separated

of the previous phase in a solid phase and a liquid phase.

By this procedure, after the solid solid separation a solid phase (FS) and a liquid phase (FL) are obtained which in turn is composed of an aqueous phase highly enriched in compounds of interest (mainly polyphenolic compounds), plus a compound oil phase by residual olive oil.

In a preferred embodiment, the process of the invention comprises a stirring / homogenization stage after the residue mixing stage.

We will now explain the procedure in more detail:

Mix of solid waste and liquid waste from oil mills (E1)

In this sense, examples of liquid residues are the olive wash water, the oil wash water, the vegetable water and the brine used in the processing of table olives. On the other hand, examples of solid residues are pomace, alpeorujo or olive bone.

The solid (RS) and liquid (RL) residues will preferably be mixed in a ratio between 1: 1 and 1: 12, more preferably between 1: 1 and 1: 6, and even more preferably between 1: 1 and 1: 4. Thus, for each liter, L, of solid waste, between 1 and 12 L of liquid waste will be added to the mixture, preferably between 1 and 6l, more preferably between 1 and 4L.

In a particular embodiment, intended for oil mills that operate with the two-phase system, the solid residue, alpeorujo, obtained as a by-product of the horizontal centrifugation of the olive paste, will be mixed with the liquid phase obtained at the exit of the Vertical centrifuge of the oil washing process (oil washing water).

In another particular embodiment, for oil mills that operate with the three-phase system, the pomace (solid residue) is mixed with the vegetable water (liquid residue), both generated in this case in the vertical centrifugation process.

Preferably, the residues of the oil mills that are intended to be treated will be collected directly and immediately at the exit of the horizontal decanter and the vertical centrifuge, respectively, during the continuous process of obtaining olive oil in the oil mills themselves, to avoid processes of self-fermentation of the residues that alter the composition of the same that would act increasing on the one hand its phytotoxicity and on the other causing the loss of compounds of high added value.

Optionally, the solid residue may be previously boned before being introduced into the mixing tank.

Preferably, the mixture of solid and liquid waste is stirred to achieve a homogeneous solution. For this, the mixing will preferably be carried out in a mixing tank equipped with a stirrer. This agitator can be a propeller or turbine type agitator, with several propeller or turbine elements along the longitudinal axis of the agitator for a homogeneous and perfect mixture of the solid and liquid phases.

Liquid-Solid Extraction of Compounds (E21

Then, the solid-liquid extraction stage (E2) takes place in any container suitable for carrying out the extraction phase, hereinafter "mixing tank" (T). In this step, compounds of interest are extracted, such as, for example, bioactive compounds such as hydroxytyrosol, thiol, 3,4-dihydroxyphenyl glycol, oleuropein or pyrocatechol. This stage is characterized in that the extractant phase comprises at least 5% water, preferably more than 10%, more preferably between 20 and 30% water and even more preferably in 25% water volume.

Preferably, the extractant phase consists only of the water contained in the mixed waste.

In a particular embodiment, the extractant phase consists mostly of the oil wash water (liquid phase) and the extract phase is the alpeorujo (solid phase). This embodiment is particularly convenient if the waste comes from two-phase oil mills.

In another particular embodiment, convenient if the residues come from three-phase oil mills, the extractant phase consists mostly of the washing water of the olives.

Preferably, the duration of the solid-liquid extraction process should be between 0.5 and 24 hours, preferably between 1 and 12 hours, more preferably between 1.5 and 4 hours. Also, the stirring speed should be between 20-1000 rpm, preferably between 20-500 rpm, preferably between 40-200 rpm, to ensure as homogeneous contact as possible in the solid-liquid interface.

During the solid-liquid extraction stage of the extract phase by the extractant phase the temperature is preferably maintained at a value between 15-50 oC, more preferably between 15 -40 oC, and even more preferably between 20 -40 cC.

This temperature is in the same range as the outlet temperature of the liquid and solid by-products in the oil production processes (vertical and horizontal centrifuges) and therefore no additional heating is necessary at this stage, thus ensuring the economic efficiency of the proposed process, compared to the procedures known in the state of the art.

If necessary, in order to maintain the temperature, indirect heating means are preferably used, avoiding direct heating systems, such as water vapor heating systems, which would lead to dilution of the mixture.

By maintaining the temperature, during the extraction process, within the aforementioned intervals, the loss of polyphenolic compounds by volatilization or degradation is avoided.

In said solid-liquid extraction stage, the mixing tank will preferably be hermetically sealed, to avoid the loss of volatile bioactive compounds during the referred mixing and extraction stages. At the end of the solid-liquid extraction stage, the concentration of total phenolic compounds extracted in the liquid phase will be between 5 and 10 times greater than that of the initial effluent (oil or olive wash water, brine or alpechin), arriving In some cases to be 15 times higher.

The way of carrying out the extraction phase makes it possible to avoid adding additional reagents in the process, reusing the own by-products of the production process to obtain, at the end of the process of the invention, a by-product rich in antioxidant compounds of high added value, and by another, an aqueous residue with a minimized organic load that can be used in irrigation or dumping.

It is also not necessary to add any organic or other exogenous solvent, with the consequent economic, environmental and safety advantages that this entails with respect to the procedures known in the state of the art.

Solid-liquid separation (SIl) (E3)

In this step (E3) a density separation process or, preferably, a filtration process is performed, preferably a filtration process using vacuum or centrifugation or a combination of any of the above processes in any of the possible sequences, which results in to two phases: a solid phase (FS), mainly composed of spent alpeorujo or pomace, understanding as such a solid residue with a negligible or industrially unprofitable amount of compounds of interest such as polyphenols, and a liquid phase (FL) that at its It is also composed of an aqueous phase enriched in polyphenolic compounds, and a 0leos phase8.

The solid phase (mainly spent pomace or spent alpeorujo) will be between 25 -35% by weight with respect to the initial weight of solid waste (alpeorujo or pomace) and liquids (oil wash water or olives). The solid phase can be taken to composting (to obtain fertilizers) or anaerobic digestion (to obtain biogas and / or biohydrogen).

In a particular embodiment, the solid-liquid separation is carried out by filtration using vacuum, this is preferably carried out at room temperature, with a filter of between 1 -1000 µm, preferably between 1-200! 1m, more preferably between 50 -100! -1m. By vacuum filtration, two phases are mainly obtained, (FS) a solid phase and (FL) a liquid phase in turn composed of an aqueous phase (FL.1) highly enriched in bioactive compounds of interest (mainly polyphenolic compounds), plus an oil phase (FL.2) composed of residual olive oil extracted from both initial solid and liquid waste.

In another particular embodiment the solid-liquid separation is carried out by centrifugation. The centrifugation is carried out at room temperature, in a horizontal or vertical decanter, preferably in a vertical centrifuge, at an angular speed comprised between 100 -10000 rpm, preferably between 200-5000 rpm, preferably between 1000-5000 rpm. By centrifugation two phases are obtained, (a) a solid one, which will remain at the bottom, and a (b) liquid in turn composed of (b.1) an aqueous phase highly enriched in bioactive compounds of interest that will remain in the intermediate part, plus (b.2) an oily phase composed of residual olive oil extracted from both initial solid and liquid residues, which will remain at the top, due to density differences.

Additional stages

The process of the invention can be optimized by performing several additional steps:

Oil phase and water phase separation (Figure 2 S)

In a particular embodiment the process of the invention comprises a stage that separates an aqueous phase and an oil phase from the liquid phase obtained after solid-liquid separation.

After the SIL separation stage, the resulting liquid phase is maintained at rest so that the oil phase (FL.2) will remain in the upper part of the solid-liquid suspension due to density differences (lower oil density compared to the aqueous phase ), can be easily removed and collected using a mechanical system for use as virgin olive oil, since it has not undergone any chemical process, and will involve between 1% and 10% w / w with respect to the solid mixture - initial liquid, preferably alpeorujo or orujo mixed with oil wash water or olives.

The aqueous phase (FL.1) obtained by the process of the invention, located at the bottom, will be directed to a subsequent membrane stage for fractionation and concentration once the oil phase is separated as described. The aqueous phase obtained will suppose between 65% and 75% by weight with respect to the initial weight of the mixture, solid and liquid waste.

If, after the SIL separation, solid residues are dispersed in the liquid phase, they will be deposited by sedimentation in the lower part of the tank and incorporated into the rest of the solid phase obtained in step E3 after obtaining the aqueous phase.

At the end of the SIL separation stage, the concentration of total phenolic compounds extracted in the aqueous phase will be between 10 and 20 times greater than that of the starting liquid waste, in some cases becoming 30 times higher.

Nanofiltration

In another particular embodiment, the liquid phase obtained after the SIL separation stage, and in particular the aqueous and oily phases, preferably the aqueous phase, is fractionated and concentrated by nanofiltration, obtaining a product with a high concentration of polyphenolic compounds.

In the case of the aqueous phase, a product with a concentration between 500 mg / L and 3000 mg / L, mostly hydroxytyrosol, and a heterogeneous polyphenolic profile can be obtained.

Thus, in a particular embodiment (Figure 3), the aqueous phase obtained by separation, will subsequently be subjected to a membrane nanofiltration stage for its fractionation and concentration, purified with respect to other compounds existing in the mixture.

The nanofiltration stage to carry out the fractionation and concentration (purification) of the aqueous phase will consist of a nanofiltration operation, with membrane modules either in flat, spiral, or tubular configuration, preferably in spiral configuration, with nanofiltration membranes either polymeric or ceramic, preferably polymeric.

The nanofiltration stage will be carried out in load mode or semi-continuous, at a temperature between 15-50 ce, preferably between 15 -40 oC, preferably between 20 -40 oC, and at a medium-low working pressure, between 1-40 bar, preferably between 5 -30 bar, preferably between 5 -20 bar, in line with the temperatures of the stages described above, to ensure the energy efficiency of the proposed process. Although previous studies have indicated that membrane methods lack technical and economic efficiency when using vegetable water as a starting material, in the proposed process it has surprisingly been found that the inclusion of the stages prior to this stage, described above, enhances the effectiveness of the proposed nanofiltration stage. Without the removal of the solids in suspension and oil phase achieved in these previous stages, the membrane tends to fill quickly, rendering the proposed process inefficient. In addition, the indicated temperature range is key to avoid damaging the matrix, with the consequent loss of polyphenolic compounds due to volatilization or degradation, and also said temperature during the extraction process is in the same range as the outlet temperature of the by-products liquid and solid in the vertical and horizontal centrifuge, respectively, and in the range of the proposed previous stages, therefore no further heating is necessary in this nanofiltration stage, thus ensuring the economic efficiency of the proposed process, compared to the procedures known in the state of the art. In this sense it is important to note that studies proposed in the state of the art operate at very high temperatures, which leads to the degradation and loss of said bioactive compounds.

At the end of the nanofiltration stage of the aqueous phase, a liquid residue will be obtained

(R) with a minimized organic load that can be spilled without problems or used in irrigation since its solids content in suspension and organic load is less than 500 mg / L and 1500 mg / L; and a by-product (P) in which the concentration of total phenolic compounds will be between 10 and 35 times higher than that of the initial effluent, preferably between 20 and 35 times higher, where hydroxytyrosol will represent between 5 -10% of the concentration total, reaching in some cases up to 15%.

The concentrate obtained has highly antioxidant, antimicrobial, anti-inflammatory and anticarcinogenic properties, with a high concentration of polyphenol compounds of low molecular weight, particularly in hydroxytyrosol, but with a heterogeneous and synergic polyphenolic pertile, such that it confers a biological activity superior to that observed for isolated hydroxytyrosol.

This concentrate rich in hydroxytyrosol may have a liquid or solid form

or powder by drying with spray-dry or lyophilization. The hydroxytyrosol-rich concentrate may optionally be in the form of an emulsion or vehiculized in the form of solid lipid nanoparticles, enabling and enhancing its subsequent incorporation into solid or liquid matrices of hydrophilic or lipophilic character.

Boneless Previous

Prior to the solid-liquid mixing and extraction stage, the extract phase (alpeorujo or pomace) may be totally or partially boned before entering the reactor, causing it to pass through a sieve with a light size between 0.1 -5 mm, preferably between 0.1 -3 mm, preferably between 0.5 -2 mm, thus also allowing the recovery of the olive bones for subsequent direct or indirect use (pellets) for energy production.

Acid Hydrolysis Optionally, and before, simultaneously or after the extraction stage

solid-liquid of compounds of interest of the extract phase and the extracting phase an acid hydrolysis step of the solid-liquid mixture may be carried out, consisting of the addition of a well acidic agent (a) to the solid waste mixture and liquids, or (b) to liquid wastes (in a particular embodiment, oil wash water) prior to mixing with solid wastes (in a particular embodiment, alpeorujo).

The acid hydrolysis stage will be carried out at room temperature, or at the temperature of the solid-liquid extraction process.

The acidic agent added in the hydrolysis step is a food grade acid, preferably selected from hydrochloric acid, sulfuric acid, phosphoric acid or citric acid.

The purpose of this stage is to avoid the self-fermentation of the by-products that alter their composition by increasing their phyto-toxicity on the one hand and on the other causing the loss of compounds with high added value.

At this stage, part of the load present in the matrix of both residues, such as cellulosic, hemicellulosic and lignin fibers, oil globules and pulp residues, is reduced and separated into aqueous suspensions, facilitating its solubilization and transfer to the liquid phase , improving its subsequent filterability.

System of the invention

Finally, a system for the treatment of waste from oil mills and obtaining by-products of industrial interest is also object of the invention, comprising means for carrying out the process in any of its possible implementations.

In a particular embodiment, this system comprises a boning system, a mixing tank, a hydrolysis reactor, an agitator, a centrifuge, an oily phase mechanical removal system, a nanofiltration membrane equipment, a drying equipment. spray-dry

MODE OF REALIZATION

Procedure used in an oil mill with two-phase extraction process

The proposed process comprises a first stage of mixing the solid residue with the liquid residue, which will be carried out in a closed reactor type mixing tank, equipped with a turbine type agitator. Two streams of samples obtained in-situ, directly and immediately at the exit of the horizontal decanter and the vertical centrifuge, respectively, of an oil mill operating with the two-phase system giving rise to two types of waste are introduced: alpeorujo (solid waste) and an oil wash water (liquid waste), the weight: volume ratio of solid and liquid waste being equal to 1: 2. The alpeorujo was previously boned by means of a 1 mm sieve, obtaining 15% by weight of removed olive bone and the remaining boneless alpeorujo.

Next, the solid-liquid extraction step of compounds of interest (bioactive compounds) is carried out, the mixture of solid and liquid residues being continuously stirred at a stirring speed of 200 rpm, for 1 hour and at a constant temperature of 35 oC . To maintain this temperature, an indirect heating system was used.

Next, a solid-liquid separation (SIL) process is carried out in a vertical centrifugation system, at an angular speed of 3000 rpm, at the outlet temperature of the previous stage. After this stage, a solid phase (spent alpeorujo) in the lower part, an aqueous phase highly enriched in bioactive compounds of interest remaining in the intermediate part, and an oil phase composed of residual olive oil are obtained by their different densities extracted from solid waste and starting liquids, which remains at the top.

The oil phase, which has not undergone any chemical process, is removed and collected mechanically for use as virgin olive oil, and represents 5% of the initial weight of the solid-liquid mixture (alpeorujo or pomace-water of washing of oil or olives), while the spent alpeorujo supposes 30% in weight with respect to the initial weight of the solid mixture (alpeorujo or pomace) - Liquid (water of washing of oil or olives).

The aqueous phase, once the upper oil phase has been removed, will be directed to a later stage 5 of nanofiltration (polymeric, composite film "thin film"

composite »of polyamide on polysulfone. with a cut size of 300 Da). The nanofiltration operation is carried out in semicontinuous, at the current output temperature of the preceding stages (35 OC) And at an operating pressure of 20 bar, obtaining an efficient permeate flow.

10 At the end of the nanofiltration stage, a permeate stream is obtained with an organic load minimized by 80%, for reuse in irrigation or discharge, and a concentrated stream in which the concentration of total phenolic compounds is more than 20 times higher than that of the starting liquid residue, where hydroxytyrosol

15 represents 15% by weight of the total, with a heterogeneous polyphenolic pertile.

Claims (17)

1. Procedure for the treatment of mill waste and obtaining by-products of industrial interest, which includes the following stages:

•

Mix of solid waste and liquid waste from oil mills

•

Liquid-solid extraction of compounds, characterized in that the extractant phase comprises at least 5% water, preferably more than 15% water, more preferably between 20 and 30% water, and even more preferably about 25 % of water.

•

Solid-liquid separation, whereby the resulting product of the previous phase is separated into a solid phase and a liquid phase.

2.

Method according to the preceding claim comprising a solid waste deboning stage performed before the waste mixture.

3.

Method according to any of the preceding claims characterized in that the solid and liquid residues are mixed in a ratio between 1: 1 and 1: 12, more preferably between 1: 1 and 1: 6, and even more preferably between 1: 1 and 1 :4.

Four.

Process according to any of the preceding claims in which the residues come from oil mills that operate with the two-phase system, the solid residue is alpeorujo and the liquid residue is oil wash water or olives.

5.

Method according to any of claims 1, 2 or 3 in which the residues come from oil mills that operate with the three phase system, the solid residue is pomace and the liquid residue is alpechin.

6.

Process according to any of the preceding claims characterized in that the extractant phase consists of the water contained in the mixed waste.

7.

Method according to any of the preceding claims characterized in that the temperature is maintained during solid-liquid extraction in a

value between 15 -50 oC, more preferably between 15 -40 oC, and even more preferably between 20 -40 oC.

8.

Method according to any of the preceding claims characterized in that the solid-liquid separation is carried out using vacuum filtration.

9.

Method according to any one of claims 1 to 8 characterized in that the solid-liquid separation is carried out using centrifugation.

10.

Method according to any one of claims 1 to 8, characterized in that the solid-liquid separation is carried out using vacuum filtration and centrifugation in any of its possible sequences.

eleven.

Method according to any of the preceding claims, which further comprises a stage that separates the liquid phase obtained by density difference after solid-liquid separation in an aqueous phase and an oil phase.

12.

Process according to any of the preceding claims which further comprises a nanofiltration step of the liquid phase obtained.

13.

Process according to claim 11, further comprising a nanofiltration step of the aqueous phase obtained.

14.

Process according to any of the preceding claims, which also comprises an acid hydrolysis stage prior to, simultaneously or after the extraction stage.

fifteen.

Process according to the preceding claim characterized in that the acid hydrolysis is carried out by adding an acidic agent to the liquid waste before mixing it with the solid waste.

16.

Process according to any of claims 14 or 15 characterized in that the acid added in the hydrolysis step is a food grade acid, preferably selected from hydrochloric acid, sulfuric acid, phosphoric acid or citric acid.

17. System for the treatment of waste from oil mills and obtaining by-products of industrial interest comprising means for carrying out the process according to any of the preceding claims.