MX2013000943A - Method for conditioning wastewaters resulting from the nixtamal, masa and tortilla industry. - Google Patents

Abstract

The novel method for conditioning wastewaters resulting from the nixtamal, masa and tortilla industry, known as nejayote (corn nixtamalization effluent), is intended to remove suspended solids in order to obtain a product ideal for different purposes, the method including the following steps: (a) conditioning nejayote: (b) conditioning the hydrolase enzyme; (c) incubating the resulting mixture; (d) adding a flocculant; (e) separating the flocculated material of the clarified nejayote, completely removing any suspended material. The clarified product, nejayote free of suspended solids, is useful as raw material for processes or technologies intended to recover compounds with commercial or strategic value such as: phenolic compounds, carbohydrates, salts or water for being reused or discharged in an environmentally safe manner.

Description

METHOD FOR THE CONDITIONING OF WASTEWATER IN THE INDUSTRY OF NIXTAMAL, LA MASA AND LA TORTILLA TECHNICAL FIELD OF THE INVENTION The invention relates to a novel method for the conditioning of wastewater resulting from the nixtamal, dough and tortilla industry, commonly known as nejayote. More particularly, it refers to a chemical and / or enzymatic method for flocculating and removing solids in suspension, obtaining a product suitable for use for different purposes.

BACKGROUND OF THE INVENTION The nixtamalization is an ancestral process that consists in cooking corn grains in alkaline water. The cooked grains are then ground and the product known as masa is used to make the tortilla, the staple food of the Mesoamerican peoples' diet and whose use has spread throughout the world. In an industrial mode, the dough is dried and ground for sale as nixtamalized corn flour. In any case, the alkaline cooking water and the washing waters of cooked corn grains are commonly known as nejayote, which is an effluent rich in organic material formed, both by suspended solids and solids in solution. Unlike maize soaking water produced by the starch industry, the nejayote composition is highly complex since it contains the products resulting from the alkaline hydrolysis of the pericarp and part of the grain endosperm. The high concentrations and complexity of organic material, pH and temperature high, make the nejayote is considered a highly polluting effluent.

The relationship, concentration and nature of the compounds resulting from nixtamalization depend on several process parameters, which include the corn variety, endosperm hardness, quality and integrity of the grain, type and concentration of lime (Rosentrater , 2006, Waste Management 26, 284-292), temperature and time of cooking and soaking. According to the same author, there are 12 reports that allow establishing a range of 0.5-14.5% loss (dry weight) of corn components during nixtamalization that equate to a range of 2500 to 50000 mg of total solids / L of nejayote. Of these quantities, the suspended solids can range between 2350 to 5500 mg / L. These suspended solids are generally partially removed by screening or filtration, centrifugation or decanting (Rosentrater, 2006, Waste Management 26, 284-292). Ramírez-Romero et al., 2011 (Proceedings of the International Symposium on Conventional and Alternative Teenologies in Corn Processing, Chihuahua, Chihuahua, Mexico) point out that by using flocculants and a subsequent sedimentation, they manage to reduce suspended solids to a average concentration of 2100 mg / L, from nejayote samples with an average initial content of 4500 mg / L. The same author, jointly Vinlegra in 2007, describe in the patent application MX 2007010310A that the addition of an aluminum flocculant manages to reduce the suspended solids to levels that comply with the Mexican standard (<200ppm). The solids in suspension, partially removed are disposed in sanitary landfills (Rosentrater, 2006, Waste Management 26, 284-292) or employees for livestock feed (Velasco-Martínez et al., 1997, Poultry Science 76 (11), 1531- 1534).

The retentive solids in suspension are usually very small, with sizes ranging between 0.5-15 m? Ti, so they lack the mass necessary to be separated by gravitational force in settlers or by the action of centrifugal force in centrifugal separators. Due to their small size, they are not able to form flocs even with the help of flocculants, except in some cases at very high concentrations, mainly associated with adsorption phenomena. When these fine solids in suspension reach a filtering surface, they quickly cover or clog the pores or interstices of the filter forming an incrusting film, difficult to remove, which obstructs the passage of the liquid. For this reason, filtration, in any of its modalities, is not an option for the total removal of solids in suspension. Until now, the nature of these small particles in suspension had not been studied, not knowing their composition since by the type of process, their characteristics are very different from the solids that are generated in the processes of the starch industry, much more studied that the nixtamal industry, the dough and the tortilla.

However, the nejayote also contains a series of products with commercial or strategic value for the recovery and use of which different processes or technologies have been developed, in which it is necessary that this effluent be free of suspended solids. For example, in the patent of Asaff et al, 2008, MX 259521 for the recovery of ferulic acid from nejayote refers to the use of adsorption / desorption processes developed in packed columns. It is known that to guarantee the continuity of this type of operations it is essential to reduce to the maximum the presence of any particle suspended in the influent since the frequency of backwashing is exponentially related to the presence of solids in suspension. The aforementioned patent makes reference that the reduction of suspended solids can be carried out by filtration or centrifugation although, as mentioned above, neither of these two operations allows a complete removal of this industrial level material.

On the other hand, the Carvajal-Millan et al. Patent, 2005, MX 278768 refers to a process for the recovery of fermented and non-fermented pentosans contained in the nejayote. The second step of this process describes the use of a laboratory centrifuge operated at 10,000 rpm for 15 minutes to precipitate the solids in suspension. At an industrial level, there are no centrifuges that operate at such speed and in the best of cases, tests carried out by our research group showed that even vertical high-efficiency centrifugal separators manage to reduce the amount of suspended particles to a maximum of 70 mg / L. .

During the last years, the accelerated development of new materials has allowed the manufacture of multiple types of membranes of different pore sizes. Currently, it is increasingly common to use micro, ultra and nano filtration membranes, as well as reverse osmosis for the treatment of wastewater and various industrial processes. For example, in the Potter patent, US Pat. No. 5,707,524, a process and a system for the treatment of wastewater from different industries containing carbohydrates, as a fermentable material for the production of yeasts, is described. Said patent describes the use of ultrafiltration membranes to concentrate the fermentable material and generate water for reuse or delivery to drainage containing a minimum amount of contaminants. However, a condition for the application of this type of technology is that the wastewater contains a minimum or no amount of suspended solids and is free of sticky or fouling material, which in the case of nejayote, has been impossible to achieve with the technology available so far.

OBJECT OF THE INVENTION In view of what has been described above and with the purpose of solving the constraints encountered, it is the general object of the invention to provide a unique, innovative and efficient method, which has a direct application as one of the last stages of the processes of the industries of nixtamal, nixtamalized corn flour and tortilla, for the partial treatment of its wastewater, commonly known as nejayote.

Another general object of the invention is to provide a unique, innovative and efficient method for conditioning the nejayote in order to obtain a product free of solids in suspension, suitable for use in processes aimed at the recovery of valuable compounds. commercial or strategic content in these wastewater.

It is a specific object of the invention to provide free nejayote of suspended solids for use in processes which in turn have the purpose of recovering high value products contained in the nejayote, such as phenolic acids, particularly ferulic acid, its dimers, trimers , its glycosylated esters, p-coumaric acid and 4-vinyl guaiacol, among others.

It is another specific object of the invention to provide free nejayote of solids in suspension for use in processes which in turn aim at the recovery of products of commercial value contained in the nejayote, such as pentosanas and fermented pentosanas.

It is another specific object of the invention to provide free nejayote of solids in suspension, for its treatment through membrane technology, such as ultrafiltration and / or nanofiltration or other conventional technologies for the purpose to obtain treated water for reuse or for its discharge in an environmentally safe way.

In one of the preferred embodiments of the invention, which includes at least some of the objectives presented above, it comprises a method that allows to dissolve the finely particulate suspended material of the nejayote, which is the one that causes the incrustation and premature clogging of any surface or filtering body. This finely particulate material that until now could not be eliminated by any unit operation or known method at a reasonable cost, is hydrolyzed enzymatically and / or chemically under conditions of established pH and temperature to minimize the treatment time. The rest of the suspended material that is not hydrolyzed is then rapidly flocculated by the addition of a suitable flocculant and the adjustment of the ionic strength of the medium. The separation of the flocculated material can be carried out by sedimentation, filtration, centrifugation or combinations of these unit operations. The effluent, free of solids in suspension, is considered a product ready to be used in different processes.

BRIEF DESCRIPTION OF THE FIGURES The characteristic details of the invention are described in the following paragraphs in conjunction with the accompanying figures, which are for the purpose of defining the invention but without limiting the scope thereof.

Figure 1 shows a schematic diagram of the method of the present invention for the treatment of nejayote.

DETAILED DESCRIPTION OF THE INVENTION The method for conditioning the nejayote, in one of its preferred embodiments, is described with reference to Figure 1. The first step 10 of the entire process is the nejayote analysis. It is the characteristics of this effluent that determine the specific parameters of operation of the method and therefore of the entire process. Particularly important are the content of solids in suspension, the solids content in solution, the pH and the temperature. On this basis, the proportion of acids, enzymes and flocculants to be added in the subsequent steps will be established.

The second step of the inventive process is step 20, referred to the adjustment of the pH according to the needs of the subsequent steps of the method or the use that it is going to have. For example, the patent MX 278768 refers to the need to lower the pH of the nejayote to 5 for the purpose of stopping the hydrolysis reactions. On the other hand, the patent MX 259521, details that the pH of the nejayote must be decreased to values between 3 and 5 with the purpose of favoring the adsorption of the molecules of interest. In the event that the object of use was the recovery of water, a pH close to neutrality may be desirable. The pH adjustment can be carried out by the addition of phosphoric acid or one of its salts or sulfuric acid or hydrochloric acid or a mixture of any of these acids in an amount such that the pH is lowered to values in the range of 4.0 to 6.5, preferably between 5.0 to 6.0.

The third step and central part of the inventive process is step 30, referred to the enzymatic hydrolysis of the fine material in suspension of the nejayote which is the one that causes the incrustation and premature clogging of any filtering surface or body. Until now, the nature of this fine material in suspension was unknown, so there are no reports in the literature or in banks of patents, presuming that it could be lignocellulosic material, hemicellulose and / or starch. Therefore, a selection of enzymes capable of hydrolyzing this material should be carried out, as detailed in the first example, resulting in the most effective enzymes of the α-amylase type. This fact means that the fine material in suspension is formed mainly by small granules of starch that are detached from the endosperm and whose size ranges between 0.5 and 15 m? Ti. This suspended material is one of the main contributors to the turbidity of the nejayote, it is the one that quickly obstructs any filtering surface or body and because of its size, it can not settle or be separated by forces greater than gravitational, such as those generated in separators. Centrifugal The optimum pH for the development of the activity of the α-amylase type enzymes ranges from 4.5 to 6.5. It was observed that the process of enzymatic hydrolysis is favored at temperatures above 70 ° C, which is usually the discharge temperature of the nejayote, and after adjusting the pH to values close to 5, possibly because chemical hydrolysis also occurs on a small scale. The time of incubation or hydraulic residence to completely hydrolyze the fouling material depends on the specific activity of the enzyme used, its volume in proportion to that of the nejayote, the content of suspended solids and solids in solution and the temperature. In the case of solids in solution, certain fractions such as dextrins enter into competition with the active site of the enzyme and may delay the hydrolysis of the fraction of interest. Usually the incubation or hydraulic residence time is in a range of 30 seconds to 90 minutes, preferably in the range of 5 to 30 minutes.

The hydrolysis is followed almost simultaneously by a flocculation of the remaining suspended or non-hydrolysed solids, which is the operation that forms the fourth step or step 40 of Figure 1. The effective flocculation of the suspended material is achieved by the addition of a suitable flocculant, besides that the own hydrolysis causes a decrease in the viscosity of the fluid, favoring the flocculation speed. The amount of suspended solids that are flocculated can range in the range of 2000-6000 ppm. The most suitable flocculant at different pH values was chosen from at least 20 types, including cationic, anionic, aluminum salts, biopolymers or diatomaceous earths. The most effective flocculants were from the group of cationic type flocculants, preferably those of the polyc acrylamide type for food use. In the case of cationic flocculants, the optimum amount to reach for an effective flocculation is from 5 to 100 ppm, preferably from 15 to 50 ppm. At acidic pH, it is important to consider the ionic strength of the medium on the density of the floccules since at higher ionic strength the density is lower but practically all the suspended material is flocculated. At lower ionic strength, the density is higher but effective flocculation of all the material is not achieved. Therefore it is necessary to consider that within the acids used for pH adjustment, at least one third is phosphoric acid or some of its salts or an equivalent polyprotic acid. The time required to achieve effective flocculation and sedimentation ranges from 10 to 120 minutes, preferably between 30 and 60 minutes, and depends on the content of suspended solids, the ionic strength of the medium and the type of flocculant used. The separation of the flocculated fraction from the supernatant free of suspended solids can be achieved by simple sedimentation or decantation, centrifugation, filtration, flotation or a combination of any of these unit operations.

It is critical to consider the order of the sequence of operations described above. For example, if the nejayote is first treated with a flocculant, much of the solids in suspension are settled but still a fraction of fine solids remains in suspension. In jars tests it was observed that the content of suspended solids remaining, after the addition of any of The types of flocculants tested at different pH and at different concentrations ranged in a range of 70 to 1500 ppm. That is, in some cases a very good degree of removal of suspended solids was achieved but in no case was their total removal achieved. In the cases in which the highest degree of removal was achieved, the use of enzymes was tried to eliminate the remaining fine solids in suspension, but neither did the desired effect of their total elimination. In some cases its reduction was achieved up to values close to 50 ppm but the remaining insoluble material could not be easily removed by filtration or centrifugation. In the first case, the filtering material was quickly clogged by the small particles in suspension and by centrifugation high speeds (> 10,000 rpm) were necessary for at least 15 minutes, an aspect that was totally impractical at the industrial level. Even, not even the addition of larger quantities of flocculants favored their separation either by decanting, filtration or centrifugation. The effectiveness of the method developed for the total removal of the solids in suspension contained in the nejayote, then results from an exact combination of conditions, sequence of operations and careful selection and application of enzymes and flocculants, resulting in a suitable product for different uses corresponding to the last step, represented as 50 in Figure 1. The flocculated fraction is a waste that is usually disposed in landfills or used for animal feed.

It is obvious to a person skilled in the art that the method so far described can be developed in a batch, semi-continuous or continuous system. In the case of a batch system, steps 20, 30, 40 and 50 of the Figure 1, can be carried out in a tank with mechanical or pneumatic agitation, with a conical bottom to facilitate the drainage of flocculated suspended solids. In the case of a semi-continuous system, steps 20 and 30 can be developed in a tank similar to that of a batch system but the addition of flocculant can be done online and phase separation performed in a continuous equipment. By example can be used a hydrosedimentador, a filter, a centrifuge or a flotation system taking care that the hydraulic residence time in the system is adequate to achieve efficient flocculation and separation. Finally, in a continuous system, the pH adjustment can be carried out online, as well as the addition of enzymes, using a step tank with a continuous loading and unloading regime and a volume such that the hydraulic residence time is the necessary for achieve hydrolysis of the material of interest. Instead of a tank, a tubular piston-flow reactor or its equivalent can also be used, which would be a long pipe but confined to a compact arrangement with enough steps to reach the hydraulic residence time necessary to achieve hydrolysis of the pipe. Material of Interest. Then, the addition of flocculants can also be done online and perform the phase separation in the equipment already described for a semi-continuous system. It is also evident to one skilled in the art of technology that in any of the operating regimes the systems may be instrumented and automated to the desired level.

EXAMPLES OF EMBODIMENT OF THE INVENTION The invention will now be described with respect to the following examples, which are solely for the purpose of representing the manner of carrying out the implementation of the principles of the invention. The following examples are not intended to be an exhaustive representation of the invention, nor are they intended to limit the scope of the invention.

Example 1 Beakers containing 500 mL of nejayote were prepared, with an initial pH of 11 and a temperature of 70 ° C. Enzymatic cocktails (50 mL) were applied with different activities allowing to act for a space of 50 minutes at the end of which a cationic flocculant was added, stirred and we expected to settle for a period of 10 minutes. At the beginning of the experiments the pH was adjusted with phosphoric acid (85% v / v) and except for treatments 3 and 4 in which the initial temperature was maintained, the other treatments were left at room temperature, recording the final temperature. The total suspended solids (TSS) in the supernatants was measured as the response variable. It was observed that the selected flocculant alone achieved a removal of more than 80% of the SST, its action being favored by a maintenance of the discharge temperature (treatment 4). This effect is due to a lower viscosity of the medium and a slight hydrolysis of the material in suspension at acidic pH. Of the enzymatic treatments applied, the most effective were those that included activities of the amylase type (19, 20 and 21), demonstrating that the fine material is suspension causing the turbidity and rapid clogging of any body or filtering surface are starch granules and / or dextrins. The supernatants of treatments 19, 20 and 21, could then be easily filtered leaving a totally free SST material.

N ° Activity pH T, (° C) SST (ppm) 1 Control l (without enzymes, without flocculant) 11 55 1347- 2 Control 2 (without enzymes, without flocculant) 5 55 1254 3 Control 3 (without enzymes, without flocculant) 5 70 1123 4 Control 4 (without enzymes + flocculant) 5 70 181 5 Control 5 (without enzymes + flocculant) 5 55 247 6 Xylanase, cellulase and glucanase 5 55 221 7 Cellulase and beta glucanase 5 55 253 8 Cellulasa 5 55 215 9 Endoglucanase and xylanase 5 55 263 10 Beta glucosidase 5 55 211 11 Hemicelulase 5 55 223 12 Cellulase and xylanase 5 55 189 13 Xylanase 5 55 193 14 Cellulase, endoglucanase 5 55 245 15 Feruloyllesterase 5 55 244 16 Beta glucanase 5 55 237 17 Pectinase 5 55 178 18 Pectinase and feruloyllesterase 5 55 193 19 Glucoamylase 5 55 12 20 Alpha amylase 6 55 15 21 Alpha amylase 5 55 27 Example 2 Beakers containing 500 mL of nejayote were prepared, with an initial pH of 11. Three treatments and an absolute control were applied, measuring the total suspended solids (TSS) in the supernatants and the supernatant as the response variables after one hour. volume of precipitated flocs (V). In all cases, at the beginning of the experiment the pH was adjusted to 5.0 with phosphoric acid.

Control Treatment 1 Treatment 2 Treatment 3 flocculant (mL) 17 17 2 Enzyme (pL) 50 50 T0 (° C) 65 65 65 65 TF (° C) 50 50 50 50 SST (ppm) 800 150 80 4 V (mL) < 50 87 96 105 caryonic polyacrylamide flocculant, initial concentration 1000 ppm. 2 Enzymatic cocktail with glucoamylase activity; specific activity 400 IU / mL (each IU equals the hydrolysis of 1 g of starch to glucose in one hour) Although the enzymes alone (treatment 2) achieve an important effect in the reduction of SST, the best effect is achieved with the addition of a flocculant; that is, by the exact combination of conditions, appropriate treatments and sequence of operations.

Example 3 Beakers containing 500 mL of nejayote were prepared, with an initial pH of 11. Three treatments and an absolute control were applied, measuring after one hour, as response variables, the suspended solids (TSS) in the supernatants and the volume of precipitated flocs (V). In all cases, at the beginning of the experiment the pH was adjusted to 5.0, with phosphoric acid.

Flocculant Control l Flocculant 2 Flocculant 3 Flocculant 10 * 100 ** 17 * Enzyme (pL) 50 50 50 To (° C) 65 65 65 65 TF (° C) 50 50 50 50 SST (ppm) 1154 150 80 9 V (mL) < 50 150 138 186 Flocculant 1: anionic, initial concentration 1000 ppm Flocculant 2: aluminum salts Flocculant 3: cationic polyacrylamide, initial concentration 1000 ppm. * in mL; ** in mg Example 4 Beakers containing 500 mL of nejayote were prepared, with an initial pH of 11. Four treatments and one control were carried out in which the pH was decreased to a value of 5.0 with 3 types of acids and the fourth with a salt and an acid . In the latter case, the amount of salt needed to lower the pH to 7 was first added and then the acid was added until reaching pH 5. In all cases, the type and dose of the flocculant were the same (35 mL of flocculant cationic (1000 ppm) / L nejayote, 100 μg glucoamylase enzyme / L nejayote).

NaH2P04 Control HCI H2SO4 H3PO4 + H2SO T0 (° C) 65 65 65 65 65 TF (° C) 50 50 50 50 50 SST (ppm) 950 85 90 3 15 V (L) < 50 97 85 280 165 Phosphoric acid is a triprotic acid, its salts can also generate anions with triple charge, which considerably increases the ionic strength of the medium. A direct relationship was established between the ionic strength of the medium and the removal of SST and inversely proportional to the density of the flocs (greater volume).

Example 5 Continuous clarification of nejayote Nejayote flow = Q = 16,000 IVh Material in solution = 12 g / L Material in suspension 3 g / L Viscosity = 2 cp Phosphoric acid flow = 24 L / h Sulfuric acid flow = 8 L / h Enzymatic cocktail flow (α-amylase, β-amylase, glucoamylase) = 1.6 L / h Cationic flocculant flow (1000 ppm) = 544 I7h Nejayote flow clarified hydrosedimentador = 12,000 L / h Hydraulic residence time in the hydrosedimentador = 30 min Suspended solids in clarified nejayote = 14 ppm Viscosity nejayote clarified = 1.3 cp Flow hydrosedimentador sludge = 4,000 L / h Solids suspended in sludge = 12 g / L Partially dehydrated sludge from centrifuges = 480,000 g / h (90% humidity) Nejayote filtration Clarified nejayote flow = 12,000 L / h Suspended solids in clarified nejayote = 3 ppm Example 6 Use of clarified nejayote for ferulic acid recovery process Adsorption columns with the following characteristics were used: 12"in diameter, 60" long; cylindrical diffusers with 0.2 mm slots; pressure drop: 0.4 Kg / cm2 (using only water as fluid), effective height of active resin of 120 cm, height of inert resin of 8 cm and an effective volume of active resin of 80 L. Adsorption operations were compared. desorption with clarified nejayote according to the method and system of the present invention (nejayote 1) and nejayote treated only with flocculant and decantate (nejayote 2) as is usually operated in the process described in the patent MX 259521.

Nejayote 1 Nejayote 2 SST (influent) (ppm) 20 145 SST (effluent) (ppm) 12 80 Dissolved solids (g / L) 8.4 8.7 Influent phenolic content (g / L) 0.8 0.8 Phenolic effluent content (g / L) 0.05 0.08 Influent temperature (° C) 48 48 Average flow rate (L / h) 620 310 Average operating time (h) 8 16 Volume of nejayote treated (m3) 5 5 Backwash cycles 0 8 Water for washing (m3) 0.6 4 Recovery performance phenolic (g / h) 470 225 Cost hours man / energy * 1 2 SST = Total suspended solids * Relative cost between both processes considering their duration After reading and understanding the foregoing detailed description of the method, in the preferred embodiments of the invention, for the conditioning of effluents from the nixtamalization process, commonly known as nejayote, the various advantages offered by said method and said system can be appreciated, for the object they were created.

Without intending to express all the relevant aspects of the invention, the following advantages can be pointed out: the method that includes the exact combination of conditions, sequence of operations and careful selection and application of enzymes and flocculants, results in a product suitable for different uses, which according to the review of the state of the art, previously was difficult to obtain.

• The method also causes a total or partial chemical and / or enzymatic hydrolysis of a fraction of the material in solution, mainly of starch fractions or dextrins, which causes a decrease in the viscosity of the nejayote. The hydrolysis of both fractions, together with the use of flocculants, causes an effective flocculation, facilitating phase separation and subsequent unit operations.

• After the enzymatic acid treatment, rapid flocculation and the acidity of the medium cause the entrainment of denatured protein, fats and oils, so that the clarification contains mainly phenolic compounds, carbohydrates and salts of commercial or bioteenological interest.

Based on the embodiments described above, it is contemplated that modifications of the described embodiments or their configurations, as well as alternative embodiments or their configurations will be considered obvious to a person skilled in the art of the art under the present description. It is therefore contemplated that the claims encompass said modifications and alternatives that are within the scope of the present invention or their equivalents.

Claims (16)

1. A continuous, semi-continuous or batch method to prepare or condition by the removal or elimination of total suspended solids (TSS), the effluents of the nixtamalization process commonly known as nejayote, where the method comprises the steps of: (a) adding to the nejayote one acid substance (s); (b) adding to the nejayote enzymes of the hydrolase type; (c) incubate the nejayote for a determined period of time; (d) adding a flocculant to the hydrolyzed nejayote; Y (e) Separate the flocculated material.

2. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, wherein step (a), is characterized by the addition of an acidic substance (s). ) to lower the pH to values between 4.0 to 6.5, preferably between 5.0 to 6.0.

3. The continuous, semi-continuous or batch method for the removal or removal of the SST from the nejayote according to claim 1, step (a), wherein the acidic substance (s) is selected from the group formed by the hydrochloric, sulfuric and phosphoric acid or any of the acid salts of the latter, preferably monobasic sodium or potassium phosphate.

4. The continuous, semi-continuous or batch method for the removal or removal of the SST from the nejayote according to claim 1, step (a) wherein the acid substance (s) is (are) added (s) alone or in the form of mixtures.

5. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, step (b), wherein the added hydrolase-type enzymes are selected from the group consisting of exo-glucanases, endo-glucanases and / or b-glucosidases, particularly from the group consisting of a-amylases, b-amylases and / or glucoamylases.

6. The continuous, semi-continuous or batch method for the removal or elimination of SSTs from the nejayote according to claim 1, step (b), wherein the enzyme (s) is (are) added alone or in form of mixtures or enzymatic cocktails.

7. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, step (b), wherein the hydrolases are added in an amount established based on the starch content of the nejayote, the activity specific enzyme or enzyme cocktail and the desired time for hydrolysis.

8. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, step (c), wherein the incubation time of the resulting mixture is 30 seconds to 90 minutes, preferably 5 hours. 30 minutes.

9. The continuous, semi-continuous or batch method for the removal or removal of the SST from the nejayote according to claim 1, step (c), wherein the incubation temperature of the resulting mixture is 20 to 90 ° C, preferably 50 at 80 ° C.

10. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, step (d), wherein the The added flocculant is selected from the group of cationic flocculants, particularly from the group of non-toxic polyacrylamides.

11. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, step (d), wherein the cationic flocculant is added until reaching a concentration between 5 to 100 ppm, preferably between 15 to 50 ppm.

12. The continuous, semi-continuous or batch method for the removal or elimination of the SSTs of the nejayote according to claim 1, step (d), wherein the time necessary to achieve adequate flocculation of the remaining SSTs is from 10 to 120 minutes, preferably 30 to 60 minutes.

13. The continuous, semi-continuous or batch method for the removal or elimination of the SST of the nejayote according to claim 1, step (e), where the separation of the flocculated material is carried out by applying the following unit operations: (a) sedimentation; (b) filtration, screening or screening; (c) centrifugation; I (d) flotation.

14. The free effluent of solids in suspension (SST) derived from the nixtamalization process, obtainable according to the method of claim 1, characterized by: (a) a content of total suspended solids (TSS) between 0 and 30 ppm; (b) a content of dissolved solids between 5 and 18 g / L; (c) a content of phenolic compounds between 0.5 and 1.5 g / L; Y (d) a pH between 4.0 to 6.5.

15. The use of the effluent derived from the free TSS nixtamalization process, obtainable according to the method of claim 1, in more efficient processes to recover compounds of commercial or strategic value contained in said effluent.

16. The use of the effluent derived from the SST free nixtamalization process, according to claim 15, wherein the compounds with commercial or strategic value comprise: a) phenolic compounds, particularly ferulic acid, its dimers, trimers, its glycosylated esters, p-coumaric acid and 4-vinyl guaiacol, among others; (b) carbohydrates, particularly of pentosans, fermented pentosans and sugars such as glucose or its oligomers (dextrins); (c) other fermentable materials, useful for bioteenological processes, including all types of carbohydrates, proteins or protein fractions and inorganic salts; Y (d) water for reuse in the nixtamalization process or discharge to the drainage in an environmentally safe manner.