Procedures for producing solid biofertilizer from liquid BIO digestion waste and said solid biofertilizer

Abstract

Procedures for producing solid biofertilizer from liquid bio digestion waste by using equipment with a static or dynamic reactor, such that with a static reactor, granulation nuclei are coated with biol in combustion equipment, and with a dynamic reactor, granulation nuclei are coated with biol in atmospheric plasma equipment with electrical discharges. A procedure is also provided for producing solid biofertilizer from liquid bio digestion waste by combining a rotating dynamic reactor with electrical discharges with a static reactor with the entry of a flow of combustion gases from a burner that allows the gases to be injected into the rotating reactor as the electrical discharges occur inside the reactor. Solid biofertilizers comprising particles consisting of granulation cores coated with biol obtained by the procedures described.

Description

[0001] PROCEDURES FOR PRODUCING SOLID BIOFERTILIZER FROM LIQUID BIO DIGESTION WASTE AND SAID SOLID BIOFERTILIZER

[0002] DESCRIPTIVE MEMORY

[0003] Field of Invention

[0004] The present invention relates to the production of a solid fertilizer, particularly by granulation in a dynamic or static reactor, more particularly using as a binder liquid residue from anaerobic digestion (biol) and as growth nuclei zeolite, dolomite and agricultural gypsum, more particularly still establishing operating conditions, which allow stable operations and production of completely coated granules.

[0005] Relationship of Prior Art

[0006] Today's society generates a large amount of waste that affects not only the air, water, and soil but also people's health. Proper waste and wastewater management, ensuring their subsequent treatment, is one of the keys to achieving a healthy and sanitary environment.

[0007] One form of waste disposal is anaerobic digestion. This is a process of organic matter degradation in the absence of oxygen, carried out by microorganisms that act inside biodigesters, which basically consist of airtight containers. Three basic products are obtained from the anaerobic degradation of organic matter: biogas, a liquid organic fertilizer commonly called "biol," and a sludge-like organic fertilizer called "biosol."

[0008] The solid and liquid waste from anaerobic digestion has extraordinary agronomic qualities that are beneficial for crops, not only due to its nitrogen, phosphorus, and potassium content, which makes it a potential substitute for synthetic NPK fertilizers, but also due to the presence of plant growth hormones, a waste product of the metabolism of the anaerobic bacteria typical of this process.

[0009] Another characteristic of the anaerobic bio digestion process is that it completely eliminates unpleasant odors and pathogenic microorganisms that may be present in the initial waste, making the biosl more feasible to use as fertilizer.

[0010] In the current transition from a fossil-based to a bio-based economy, the full utilization of nutrients typically discarded as effluents is a particular challenge, especially considering that these resources are rapidly being depleted.

[0011] Furthermore, the production of synthetic fertilizers requires significant amounts of fossil energy, which is increasingly expensive because it is a non-renewable source. Consequently, the use of biol and biosol constitutes a potential strategy to sustainably replace the use of synthetic fertilizers.

[0012] Approximately 90% of the material entering the biodigester is transformed into biosl, depending on the type of material to be fermented and the fermentation conditions. However, there are problems associated with the direct application of this liquid, such as nutrient leaching, which can lead to eutrophication of natural water bodies, altering the habitat of animal and plant populations and resulting in deterioration of water quality.

[0013] Furthermore, the transportation and storage of liquid fertilizer is a difficult operation, requiring disposal of this high-nutritional-quality product in waste water treatment plants. The alternative of converting biosl into a granulated solid would improve storage and transportation capabilities. Furthermore, the possibility of tailoring the properties of the solid product to give appropriate nutrient release profiles would reduce the leaching problem associated with the direct application of liquid fertilizer, and at the same time would offer a qualitative advantage over synthetic granulated fertilizers, by presenting traceability with a low carbon footprint, due to its organic and circular base.

[0014] Granulation techniques, which involve converting powders and / or liquids into solid granules with improved physical and / or chemical properties, are considered one of the most significant advances in the particulate solids processing industry. In particular, granulation in the fertilizer industry has made it possible to obtain granules that are more resistant to breakage, with better flow properties and less dust and agglomeration formation.

[0015] There are several types of processes for granulating without the use of a fluidized bed, such as static or dynamic reactors using combustion equipment, atmospheric plasma equipment, and combinations thereof.

[0016] Therefore, it is very useful to develop, through the granulation technique in dynamic or static reactors, a solid fertilizer using biol as a binder and different materials suitable for organic agriculture and crop needs as growth nuclei. To this end, a complete characterization of the particles that act as the granulation core in obtaining solid fertilizer is necessary, as well as their fluid-dynamic behavior in the fluidized bed and the fine-tuning of the granulation process to determine the ideal operating conditions such as temperatures, flow rates, power, etc.

[0017] Brief Description of the Figures

[0018] Figure 1 shows a preferred embodiment of a biol injection and preheating system, and granulator.

[0019] Figure 2 is a graphical representation of Wj,ac(-) versus Mesh opening (pm) particle size distribution for the different cores.

[0020] Figure 3 is a graphical representation of T (°C) versus t (min) for a dolomite overlay with T SP = 105 °C and injection pump at 15 rpm.

[0021] Figure 4 is a graphical representation of T (°C) versus t (min) for a first coating of dolomite and agricultural gypsum with T SP = 70 °C.

[0022] Figure 5 is a graphical representation of T (°C) versus t (min) for a second coating of the three materials zeolite, dolomite and agricultural gypsum with T SP = 70 °C.

[0023] Figure 6 shows the different materials in different states: (a) Uncoated zeolite, (b) Zeolite Rl, (c) Zeolite R2, (d) Uncoated gypsum, (e) Gypsum Rl, (f) Gypsum R2, (g) Uncoated dolomite, (h) Dolomite Rl, and (i) Dolomite R2.

[0024] Figure 7 shows the biofertilizer obtained in the second and third coating (zeolite 1).

[0025] Figure 8 shows a preferred embodiment of a biol feeding system.

[0026] Figure 9 shows fluidized zeolite 1 and zeolite 2 in the coating stage.

[0027] Figure 10 shows a Glow plasma setup.

[0028] Figure 11 graphically shows a comparison of water retention in a Glow plasma treated sample versus an untreated control sample.

[0029] Figure 12 shows a preferred embodiment of a fluidized bed setup with Glow plasma, where (A) is the initial state of the setup and (B) corresponds to the final state of the setup.

[0030] Figure 13 shows a comparative sample between a control sample and a treated sample obtained using the Glow plasma fluidized bed.

[0031] Figure 14 shows a preferred embodiment of an electric discharge system coupled to a combustion medium of the Bunsen burner type.

[0032] Figure 15 shows a graphical representation of the particle size distribution for different nuclei.

[0033] Figure 16 shows a preferred embodiment of a biol coating system with combustion equipment useful in the process of the present invention, where: (A) is a setup coupled to a pipe with a burner, (B) is a fully functioning atomizer, and (C) is the atomizer coupled to a system with zeolite.

[0034] Figure 17 shows the results of the thermal experiment with the biol coating system with combustion equipment in Figure 11 (A) -(C).

[0035] Figure 18 shows a preferred embodiment of a rotating tank atmospheric plasma setup, where: (A) is a schematic diagram (sketch) of the proposed setup, and (B) is the actual setup.

[0036] Figure 19 shows the mass and energy balance results of an experiment carried out using the rotating tank atmospheric plasma process with the setup in Figure 18.

[0037] Figure 20 shows a preferred embodiment of a combined test consisting of a basic simulation of the electricity production process based on gas combustion and water vapor production.

[0038] Figure 21 shows a graphical representation of the fraction of water contained in the zeolite bed as a function of the plasma power during the combined test in Figure 20.

[0039] Figure 22 shows the mass and energy balance results of the dry heat rotary tank process of the combined process of Figure 20.

[0040] Detailed Description of the Invention

[0041] Granulation Nuclei

[0042] A selection of materials was made to constitute the growth nuclei in bio slurry granulation, taking into account their physicochemical characteristics, biodegradability, availability, and cost, as well as the possibility of incorporating other nutrients, in addition to those present in the bio slurry, or presenting characteristics that contribute to the healthy development of crops and environmental protection. Consequently, three support materials were selected: zeolite, agricultural gypsum and dolomite, whose main characteristics are shown in Table 1.

[0043] Table 1. General characteristics of the materials to be used as granulation cores. Characterization of Granulation Nuclei

[0044] In order to fully characterize the materials to be used as granulation cores, a determination of the particle size distribution (PSD) of the available samples and the measurement of both the particle and solid density were carried out. Fluidization studies were also conducted in granulation reactors to establish the feasibility of using these materials. Sieving

[0045] The PSD was determined by sieving in a vibrating sieve tower (Zonytest, Argentina) with standardized meshes (ASTM) of different openings, which follow a geometric progression. The determinations were performed in triplicate. This procedure also obtained the most suitable monodisperse fractions for subsequent granulation (see Figure 15).

[0046] Density Measurement

[0047] The density of the particles, which takes into account the porosity of the particle, was determined by pycnometry. Nitrogen adsorption (NOVA 1200e from Quantachrome Instruments) was also used. This technique provides a density value that does not take into account the volume of pores connected to the surface of the particle, thus providing a value closer to the density of the solid. In particular, if the particle is not porous, both density values coincide.

[0048] Particle Size Distribution

[0049] Figure 2 shows the PSDs for the three core materials, expressed as cumulative weight fraction retained (Wi, ac). The values of the arithmetic mean diameters by mass are shown in Table 2.

[0050] Table 2. Arithmetic mean diameter by mass of the core materials.

[0051] Density Measurement

[0052] Table 3 includes the densities measured and reported in the literature for each material. For zeolite, there is a difference between the values measured by the two techniques used, indicating that it is a porous material. This characteristic is expected to make it easier for zeolite to retain the binding material during granulation. On the other hand, the densities obtained by pycnometry and nitrogen adsorption for the other two materials are similar, indicating that they are made up of non-porous particles. The results obtained are in good agreement with those reported in the literature.

[0053] Table 3. Density of the particles used as granulation cores.

[0054] Fluidization

[0055] The hydrodynamics of fluidized beds depends on the properties of the solid, such as particle size, density and shape, of the fluid, namely density, viscosity and superficial velocity, and of the bed geometry (Kunii and Levenspiel, 1991; Morl et al., 2007). The fluidizing air velocity not only affects the mixing pattern but also the stability of the operation and the growth mechanism.

[0056] Several authors indicate that the difference or ratio between the superficial fluidization velocity (u) and the minimum fluidization velocity or incipient fluidization (umf) can indicate whether agglomeration or coating of the particles occurs in the granulator (Hemati et al., 2003; Saleh and Guigon, 2007). In general, there is consensus that relatively high excess gas velocities (u - umf) lead predominantly to particle growth by coating. For this reason, it is essential to know the umf of the systems being studied. For beds of constant section umf can be calculated using equation (1), which is derived from the Ergun equation (Kunii and Levenspiel, 1991; Morl et al., 2007): where smf is the minimum fluidization porosity of the bed, pp and pf correspond to the density of the particles and the fluid, respectively; pf is the viscosity of the fluid, g is the acceleration of gravity and dp is the particle diameter.

[0057] The discontinuous fluidized bed granulator used consists of a truncated cone with an inclination angle of 6.12°. The hydrodynamic characteristics of conical fluidized beds differ from traditional columnar beds of constant cross-section. Due to the truncated cone geometry, the superficial velocity of the gas decreases from its maximum value at the base of the equipment to the surface of the bed. As a result of the axial velocity gradient, partial fluidization occurs. As the fluidization flow rate is increased, particles at the bottom of the equipment fluidize first than those at the top of the bed (Peng and Fan, 1997). For this reason, Peng and Fan (1997) proposed equation (2) to establish the value of umf in conical beds: where Do and Di correspond to the diameters of the base and top of the bed at rest, respectively; and the parameters A and B are given by:

[0058] A typical fluidization experiment involves loading the bed with particles and leveling its surface. For each surface speed tested, the system is maintained under constant operating conditions for a period of time sufficient to achieve stabilization. The bed height is then recorded by visual inspection through a glass window on the equipment. The fluidizing air velocity is measured using an anemometer at the granulator outlet, the value of which is expressed as superficial velocity at the base of the bed. Finally, the pressure drop across the bed is measured with a U-tube manometer using water as the manometer fluid. The experimental determination of minimum fluidization velocity was based on the criterion of Peng and Fan (1997), which assigns to umf the value of the air velocity corresponding to the maximum pressure drop.

[0059] Table 4 presents the minimum fluidization velocity for the three materials, both experimental (umf) and calculated by equations (1) and (2) to (4) (cylindrical umf and conical umf, respectively). The determinations were performed in duplicate or triplicate. The results indicate that both correlations overestimate the minimum fluidization velocity for the three materials, with the equation reported for cylindrical beds being more effective.

[0060] Table 4. Minimum fluidization velocities for the different cores.

[0061] For zeolite fluidization, 1,500 kg of material retained by ASTM #7 mesh, i.e., with a Sauter diameter (the diameter of a sphere that preserves the volume / area ratio) of 3.09 mm, were used. The calculated minimum fluidization velocities differ significantly from the experimental values, probably due to the non-spherical shape of the zeolite particles (see Table 4).

[0062] For the fluidization of agricultural gypsum, the material retained by ASTM #8, #10, and #12 mesh screens was used, corresponding to a Sauter diameter of 2.23 mm. A total of 1,503 kg of mass was loaded into the fluidized bed.

[0063] For the fluidization of dolomite, 2,088 kg of particles retained by different meshes were used: ASTM #8, #10, #12 and #14, with a Sauter diameter of 1.79 mm.

[0064] Granulation

[0065] In the particle granulation tests by coating, the biol provided by a biodigester was used as a binder. The physicochemical characteristics of the bio slurry were also evaluated, such as organic matter content, dry weight, pH, conductivity, size distribution of suspended solids, hydrogen, nitrogen, total carbon, potassium, and phosphorus content, to determine its agronomic potential and the possibility of using it as a binder in granulation. It was verified that the composition of the biol and its properties, except for the PSD of the suspended solids that has not been previously determined, are in agreement with data reported in the literature for biols from feeds to biodigesters similar to the one analyzed (Castro et al., 2015).

[0066] Figure 1 shows the complete system used for coating the particles. A typical experiment basically consists of three stages. First, the bed is loaded with a given mass of nuclei and fluidizing air is introduced at a speed that depends on the characteristics of the material to be granulated and at a temperature suitable for reaching the desired bed temperature. A controller manipulates the fluidizing air inlet temperature (T_a) to maintain the bed temperature at the specified value. Once the thermal regime of the bed has been established, the binder atomization stage begins for a defined time interval according to the required coverage. The biol to be fed, approximately 2 liters, is placed in a heated container with agitation to prevent the precipitation of suspended solids. The biol is injected using a pre-calibrated peristaltic pump and atomized with a given flow of compressed air that is preheated through a temperature-controlled oven. This flow is controlled by a valve and measured with a rotameter. Finally, once the injection is complete, the final granules are cooled by circulating fluidizing air at room temperature through the particle bed for a period of time that ensures proper discharge and handling of the product. The collected granular product is reserved for characterization. The dust deposited on the walls of the granulator and in the upper sleeve filters is weighed to perform mass balance closing calculations.

[0067] For all materials, two successive coating tests were carried out, i.e., a first granulation with virgin material and a second granulation with the already granulated material, to achieve greater deposition of biol on the cores. It is important to note that, in order to eliminate some of the water content present in the bio slurry, evaporation was carried out prior to the granulation stage. This process was carried out in an oven at 70°C for approximately 36 hours.

[0068] The success of coating processes is based on a correct selection of operating conditions. Taking into account the operational limits of the equipment used, the operating conditions were established by trial and error, and based on previous experience (Veliz et al., 2015). Several experiments were carried out in which attempts were made to operate the equipment by injecting biol at a constant flow rate of 0.72 cm3 / min using a peristaltic pump at 15 rpm and maintaining the fluidized bed temperature at 105 °C, controller set point, T SP. As shown in Figure 3, for dolomite granulation, this mode of operation proved to be unfeasible due to entering an oscillatory thermal regime. The control system reaches the desired set point at minute 27 of the operation, supplying fluidizing air at 120°C. However, at the beginning of injection at minute 30 of the operation, there is a sudden drop in bed temperature due to the evaporation of water from the bio slurry. In response to this disturbance, an increase in the temperature of the fluidizing air is generated. Since the equipment is not capable of operating with differences between the temperature of the bed and the fluidization air greater than 60 °C, from the 33rd minute of operation the system enters an oscillatory thermal regime.

[0069] Consequently, to avoid sudden changes in temperature and AT greater than 60 °C, the following coating tests were performed by establishing T SP = 70 °C and decreasing the injection flow rate to 10 rpm during the start of the operation, i.e., 0.44 cm3 / min, with a gradual increase up to 15 rpm once the system stabilizes at the established temperature set point.

[0070] Figure 4 shows the fluidizing air and bed temperature profiles for dolomite and agricultural gypsum coating.

[0071] It is clearly observed that when the injection of biol begins, at minute 43 of the operation for dolomite and minute 51 for agricultural gypsum, the temperature of the bed suddenly decreases, causing an increase in the inlet air temperature. In addition, a progressive increase in the temperature of the fluidizing air is observed in response to the gradual increase in the flow rate of injected biol. It is important to note that during these experiences the temperature difference never exceeded 60°C.

[0072] As can be seen in Figure 5, during the second coating no problems were detected during the operation and the bed temperature and fluidization air profiles for the three materials used as granulation cores showed the same behavior as during the first coating.

[0073] Figure 6 shows photos of samples of the three types of virgin cores and after each coating stage: Rl, first coating; R2 second coating. The adherence of the biol to the surface of the different particles that acquire its characteristic color is clearly observed. As expected, the coloration intensifies as the material regranulates (see Figure 7). Zeolite appears to be the material that achieves the greatest coating, which is consistent with the porosity of its particles. Depending on the color, the adhesion of biol to dolomite is also good, while it is poorer to agricultural gypsum. The latter could be due to the friability of the particles of this material.

[0074] Table 5 summarizes the operating conditions found to stably carry out the coating of the different materials selected as core. It is observed that the temperature of the biol differs from one experience to another because it is heated by a hot plate.

[0075] Table 5. Suitable operating conditions for granulation of the three core materials. r

[0076] Examples of Claims

[0077] Previous Assays

[0078] Characteristics of the Biol used

[0079] The biol used was characterized to determine the amount of non-volatile solids it contains. To do this, a sample of biol was dried in an oven at 106°C for 24 hours. The amount of solids contained in the biol sample was determined to be 2.1% ± 0.1%.

[0080] The solids concentration in the biol sample was 21 g / L.

[0081] Table 6 below shows the results of the tests carried out to chemically characterize the biol used in the embodiment examples.

[0082] Table 6: Results of tests carried out on a biol sample. THO D N

[0083] DETERMINAT UNIT No. 1 GUIDE VALUE ANALYTICAL METHOD

[0084] Organic Ma mg / 1 1610 0,01 NR SM 5910

[0085] Molybdenu mg / 1 21 0,05 NR SM 3111 D

[0086] Total Nitro mg / 1 140 0,01 150) SM 4500 N C

[0087] Potassium mg / 1 19 0,01 NR SM 3111 B

[0088] Total Zinc mg / 1 0,608 0,01 50) SM 3111 B

[0089] References: SM, Standard Methods (a, b, c); NR, Not Regulated; LD, Limit of Detection; NA, Not Applicable.

[0090] The instruments listed in Table 7 below were used in the determinations made.

[0091] Table 7: Instruments used in the analysis.

[0092] INSTRUMENT SERIES NO.

[0093] Precision Analytical Balance OHAUS AR2140 L0951228060362 - P

[0094] Atomic absorptionVARlAN AA50B AA0905M073 spectrophotometer

[0095] UV-Visible Spectrophotometer HACH DR6000 1544426 Table 8 below shows the environmental conditions recorded during the laboratory analysis.

[0096] Table 8: Environmental conditions during sample analysis

[0097] Temperature 23 + 8 °C

[0098] Atmospheric Pressure 1012 hPa

[0099] Humidity 50 + 20 %

[0100] Production of Solid Biofertilizer from Liquid Bio digestion Waste in Static and Dynamic Reactor Equipment

[0101] 1. Biol Coating with Fluidized Bed Combustion Equipment - Static Reactor

[0102] The objective was to obtain 4 kg of solid fertilizer based on liquid waste from anaerobic digestion and zeolite of different granulometric quality in fluidized bed equipment.

[0103] The results of the zeolite coating tests with liquid bio digestion waste (biol) obtained are detailed below.

[0104] The biol used comes from a biogas plant with a dry weight of 4.20% w / w. Dry weight tests were carried out on the biol from the biogas plant. The assays were carried out in an oven at 50 °C for 24 hours. The results are shown in the following Table 9.

[0105] Table 9. Dry weight values of biol from a biogas plant.

[0106] The cores used are made of zeolites of two granulometric qualities. Sieving tests were performed to determine the corresponding particle size distribution (PSD) and the cuts to be used as cores in the fluidized bed coating process. A Zonytest device (Rey Ronzoni, Argentina) was used for this determination, and the test was performed in duplicate. Tables 10 and 11 show the PSDs for zeolite 1 and zeolite 2, respectively.

[0107] Table 10: PSD of zeolite 1.

[0108] Size (mm) ASTM sieve % mass (1)* % mass (2)* % Average

[0109] 053 3 / 8 000 000 O00 4,76 4 33,60 34,51 34,05

[0110] 2,83 7 1,76 1,34 1,55

[0111] 2,38 8 0,43 0,33 0,38

[0112] 2,00 10 0,15 0,12 0,14

[0113] Background Background 1,69 _ 1,22 _ 1,45 _

[0114] * The % represent material retained on the mesh.

[0115] Table 11: PSD of zeolite 2.

[0116] Size (mm) ASTM sieve % mass (1)* % mass (2)* % Average

[0117] 1,68 12 5,97 5,93 5,95

[0118] 1,41 14 8,98 9,16 9,07

[0119] 1,19 16 3,31 3,00 3,16

[0120] 1,00 18 3,23 3,38 3,31

[0121] Background Background 8,74 _ 8,85 _ 8,80 _

[0122] * The % represent material retained on the mesh.

[0123] The size fractions selected for the coating tests are detailed by shading.

[0124] Successive coatings of 4 batches of zeolite of approximately 1 kg each were carried out: 2 kg of zeolite 1 and 2 kg of zeolite 2 (see Figure 9). Table 4 summarizes the total initial sample mass, spray-dried biol volume, and final sample weight, along with the estimated percentage mass gained for the total of 2 kg of biofertilizer produced from zeolite 1 and zeolite 2.

[0125] Based on the dry weight percentage of the bio slurry, the theoretical coating mass based on the atomized volume for each 2 kg batch of zeolite should be 378 g. This would result in a theoretical weight increase of 15.88% for zeolite 1 and 17.38% for zeolite 2.

[0126] It is important to highlight that fluidization generates a significant loss of the zeolite powder initially present in the samples and, in turn, attrition (erosion) of the bed particles, which makes the final weight of the product collected in the equipment chamber less than that expected to have been gained by coating with the biol. That is, the effective mass of initial zeolite on which the biol is deposited is less than the mass of zeolite that is loaded into the equipment. The dust released from the zeolite is collected in the equipment's filters and is therefore not part of the product. 60 g were collected in the filters for zeolite 1 and 76 g for zeolite 2, considering all the tests performed. This is why it is estimated that the weight gain corresponding to biol is undoubtedly greater than the percentage reported in Table 4, although there is no way to differentiate in the material collected in the equipment filters how much corresponds to zeolite powder and how much corresponds to dry biol to make the calculation based on the effective mass of zeolite available for the coating.

[0127] In summary, the effective mass percentage gained is between 15.88% and 5.6% for zeolite 1 and between 17.38% and 7.9% for zeolite 2.

[0128] On the other hand, the limit on the number of coatings was set at 3 since the last test performed for both zeolites recorded excessive attrition of the zeolite particles, which compromised the thickness of the biol layer. In addition, difficulty was detected in achieving drying of the injected biol, especially in zeolite 2, where the bed tended to defluidize in the final stages of atomization.

[0129] In Figure 7, representative images of the samples obtained after the second coating and after the third coating are presented. In the image on the right, the attrition effect mentioned above is evident, although the darker coloration shows that there was also a gain in the deposited biol layer.

[0130] As for the experimental system, a fluidized bed equipment was used with fluidization air supply at controlled temperature and flow rate and equipped with a liquid atomization system using a binary nozzle (see Figure 8).

[0131] The procedure followed for the coating is detailed below:

[0132] 1,1- Conditioning of the biol to be sprayed.

[0133] A pre-screening of the biol was carried out with an ASTM #18 sieve without noticing particles of a size that could obstruct the atomization nozzle with an orifice diameter of 0.8 mm.

[0134] The volume to be atomized was placed on a heating plate with temperature control and stirring (see Figure 2).

[0135] The biol was preheated to a temperature of 55 °C.

[0136] 1,2. Fluidizing air.

[0137] The fluidized bed blower was set to provide a flow rate of 250 m3 / h measured at T = 20 °C for zeolite 1 and 180 m3 / h measured at T = 20 °C for zeolite 2. In both cases, the air was preheated to maintain a temperature of 80 °C in the fluidization chamber. Figure 3 shows zeolite 1 and zeolite 2 in coating stages inside the equipment chamber.

[0138] 1,3- Atomization

[0139] A binary nozzle was used. The liquid biol was fed by a peristaltic pump with insulated hoses from the feed vessel to the nozzle and air by the central compressed air system (Pressure = 0.3 MPa (3 bar)).

[0140] The average flow rate of atomized biol for the production of the 4 kg batch was 33 mL / min. The average atomizing air flow rate was 15 L / min.

[0141] 1,4. Combustion setup features

[0142] The setup is coupled to a modified burner, responsible for combusting at 8 liters of gas per minute under normal temperature and pressure conditions, i.e., 1 atm / 25 °C (see Figure 16 (A)-(C)).

[0143] The flame provides 4,9 kW of thermal energy responsible for evaporating the liquid from the biol.

[0144] The biol is supplied at a rate of 23 milliliters / min for 8 hours. The exhaust gas temperature was approximately 213 °C.

[0145] Table 12. Characteristics of the rotating static tank process.

[0146] The results of the experiment are shown in Figure 17.

[0147] 1,5. Conclusions.

[0148] 72% of the total mass of the biol was incorporated into the zeolite, the remaining 28% was lost in the surroundings of the container and was released in the form of fine powder. Soot generation in the combustion system is relevant in terms of the color of the final product.

[0149] 1,6. Analytical Results

[0150] The results of the tests carried out on the solid biofertilizer obtained are shown in the following Table 13.

[0151] Table 13: Physicochemical tests and elemental analysis of the produced biofertilizer.

[0152] Note: LCM is Limit of Quantification of the Method.

[0153] 2. Biol Coating with Atmospheric Plasma Equipment - Dynamic Reactor Effects of Electrical Discharges on the Adsorption Capacity of Zeolite.

[0154] To evaluate the adsorption effects of zeolite by surface activation, a vacuum electric discharge system will be used, allowing the generation of a Glow-type discharge.

[0155] The Glow type discharge allows for a homogeneous treatment over the entire surface.

[0156] Plasma Glow Setup Features

[0157] The Glow type electric discharge system operates at vacuum pressure (<0,5 mbar) and high voltage. It is shown in Figure 10. The zeolite loading of the Glow plasma system is between 150-220g.

[0158] Results

[0159] As can be seen in Figure 11, the coarse particle zeolite treated with Glow plasma for 15 min at 1.91 mbar provides greater water retention compared to the control sample. Conclusions.

[0160] The results showed an improvement in water retention percentage of 3.7 additional percentage points over the control sample with a standard deviation of 4,48 %.

[0161] Quaternary Fluidized Bed Process (Solid — Liquid — Gas — Plasma)

[0162] Setup Description

[0163] A fluidized bed drying system with electrical discharges or quaternary fluidized bed was implemented (see Figure 12). The fluidization flow rate was 50 L / min of air at room temperature. The injected biol flow rate was 0.7 mL / min together with 4 L / min of air, through the upper part of the bed.

[0164] Results.

[0165] Erosion was detected. On the surface of the stones and generation of fine dust due to it. For this reason, the bed lost around 25% of its fine powder mass. Because of this, the metric used to quantify the mass of the coating was by apparent density. The results are shown in Figure 13.

[0166] 2,1- Atmospheric plasma setup characteristics

[0167] The setup (see Figure 18) consists of a rotating tank coupled to a stepper motor controlled by an ESP 32, a peristaltic pump responsible for transporting the biol to the rotating tank, a biol tank and a high voltage source coupled to 3 independent electrodes.

[0168] The tank is metallic and grounded, so that electrical discharges occur through the zeolite bed. The biol liquid enters the room together with the air in the form of spray.

[0169] 2.2 Biol Dispersal System

[0170] An irrigation type sprayer was used. The liquid entered the duct together with the air, dispersing the liquid horizontally along the bed at room temperature.

[0171] 2.3 Electric Shock System

[0172] The discharge system consists of three electrodes. The first of these is a long electrode that allows the electrical discharge to be carried out against the bottom of the bed. The second is an intermediate-length electrode that reaches the middle of the bed, and the third allows the discharge to be carried out against the top.

[0173] 2,4. Atmospheric Plasma System Results

[0174] The process variables are shown in Table 14. The amount of total solids injected into the system was 42 g, of which 33.6 g were fixed in the zeolite and the rest were evacuated together with the air and water in the form of steam. This represents 80% of the solids fixation rate in the zeolite.

[0175] The heating of the chamber to up to 60°C was achieved thanks to the high temperature of the plasma.

[0176] Table 14. Characteristics of the rotary tank process.

[0177] 2,5. Conclusions

[0178] Raising the temperature of 230 kg / h of air requires investing 3.5 kW of thermal energy in a fluidized bed. The demand to evaporate the total mass of water injected into the system is 2.77 kWh, achieving a total non-volatile solids fixation rate of 26.1%.

[0179] Introducing the air-dispersed fluid into the plasma system involved using a power of 500 W to execute the electrical discharges. The process inputs were at room temperature.

[0180] The biol sample differed by 1.3 percentage points from the sample performed with the conical fluidized bed test. The amount of biosl used in the test was 2 liters, with a net solids content of 42 g. Of these 42 g, 33.6 g were obtained, reported according to the increase in zeolite weight. This increase in weight represents an 80% fixation rate, which represents an improvement of 53.9 percentage points over conical fluidized bed technology.

[0181] The improvement is achieved because the retention of fine particles can be utilized to a greater extent, avoiding their entrainmentby air velocity. Thermal energy consumption is 3 kW lower than that of the fluidized bed system. The system used is 100% electric and can be combined with renewable technologies.

[0182] The system can be coupled with other energy generation sources that result in a hot air stream (30 °C < T < 200 °C) that allows the improvement and reduction of the power consumed by the plasma.

[0183] Figure 19 shows the mass and energy balance results of the experiment carried out using the rotating tank atmospheric plasma process.

[0184] Analytical Results

[0185] The results of the tests carried out on the solid biofertilizer obtained are shown in the following Table 15.

[0186] Table 15: Physicochemical tests and elemental analysis of the produced biofertilizer.

[0187] Note: LCM is Limit of Quantification of the Method.

[0188] 3. Combined Test with Combustion Equipment and Atmospheric Plasma Equipment.

[0189] Effects of Electrical Discharges on a System Coupled to a Combustion Medium for Salt Fixation in Zeolite

[0190] A system coupled with a combustion medium was evaluated to fix salts from biodigester waste. 200 mL of biol were injected, representing 4.2 g of total solids mass. Of which 0.177 g adhered, this represents that only 4.2% of the total injected mass was fixed.

[0191] Conclusions The deficiency in the biol fixing system originates due to liquid leaks from the system (see Figure 14) and the adhesion of material to the pipe walls. Based on these results, fluid leaks will be corrected, and the flue gas flow rate will be calibrated to provide the appropriate energy to instantly evaporate the injected fluid.

[0192] Simulation of the Technological Combination of the Rotating Drum with Electrical Discharges with a Combustion Air System

[0193] A simulation is performed of the technological combination of the rotating drum with electrical discharges with a combustion air system that allows the gases to be injected into the rotating drum as the electrical discharges occur inside the drum. This reduces the electricity cost due to the plasma's power consumption and allows for a reuse cycle for the remaining energy from combustion gases coming from the burner, which is responsible for replacing the exhaust gases from the motor-generators in this test.

[0194] To evaluate the combined test, a simulation was performed in Aspen Hysys V14 to determine the plasma power required to concentrate the salts from the biodigester waste. The simulation is shown in Figure 20.

[0195] 3.1 Process description and plasma power optimization under operating conditions.

[0196] The process evaluation was carried out using a calculation base of 1 kg of zeolite, where gas combustion was carried out at a rate of 1 kg / h. Combustion takes place in GBR-100 with a stoichiometric air ratio of 1.2. The power generated in GBR-100 (Flame_Power) is transferred to water to generate steam.

[0197] Steam enters the K-100 turbine where it generates electrical power at a rate of 2.6 kW with 75% efficiency.

[0198] The residual steam (3) and exhaust gases (vent) are reused in V-100 to concentrate the salts from the biol. V-100 is provided with a set of electrodes capable of generating electrical discharges that help concentrate salts on the zeolite contained in V-100.

[0199] In order to determine the optimal power of the electrical discharges under these conditions, a case study was carried out by varying the plasma power and the water concentration in the zeolite bed (see Figure 21). It was determined that under these conditions it is necessary to supply between 4-6 W / kg of zeolite depending on the temperature of the turbine steam outlet and the temperature of the exhaust gases. The process variables are shown in Figure 22.

[0200] Analytical Results

[0201] Table 16 below shows the results of the tests carried out on the solid biofertilizer obtained.

[0202] Table 16: Physicochemical tests and elemental analysis of the produced biofertilizer.

[0203] Note 1: The Conductivity resuit corresponds to a 1 / 5 dilution of the sample.

[0204] Note 2: LCM is Limit of Quantification of the Method.

[0205] Final Conclusions

[0206] The different methods and results obtained allow us to conclude that different biofertilizers can be obtained in terms of composition using the same raw material, biol, in different granulation cores, preferably zeolite. This allows for adequate variability to adapt the different products obtained to different circumstances.

[0207] Based on the laboratory results for each type of procedure, it can also be concluded that there are different methodologies that allow for the production of ammonium-free biofertilizers with only phosphorus and potassium, or more balanced biofertilizers with a higher ammonium content, making this technology highly versatile and important.

Claims

1. CLAIMS1. A process for producing solid biofertilizer from liquid bio digestion waste characterized in that it comprises the steps of: a] loading fluidized bed equipment with particles that constitute granulation nuclei, leveling its surface; b] preheating biol to a temperature between 50 °C and 60 °C; c] introducing fluidizing air at a flow rate between 150 m3 / h and 280 m3 / h and at a temperature between 110 °C and 130 °C; d] proceeding with the atomization of the biosl until the volume preheated in step b] is exhausted at a flow rate between 0.60 cm3 / min and 0.85 cm3 / min; and e] cooling the obtained granules by circulating fluidizing air at room temperature through the particle bed.

2. The method of claim 1, characterized in that the particles constituting granulation nuclei are selected from zeolite, dolomite and agricultural gypsum.

3. The method of claim 2, characterized in that the particle size is between 2 and 4 mm.

4. The method of claim 1, characterized in that prior to step b] of preheating, the biol is strained through an ASTM #18 sieve.

5. The method of claim 1, characterized in that the percentage of dry weight of the biol is between 2.5% w / w and 4.5% w / w.

6. A solid biofertilizer characterized in that it comprises particles consisting of granulation cores coated with biol obtained by the process of any of the preceding claims.

7. A process for producing solid biofertilizer from liquid bio digestion waste characterized in that it comprises the steps of:a] loading a static reactor with particles constituting granulation nuclei; b] igniting a burner capable of combusting 8 liters of gas per minute under normal conditions of temperature and pressure of 1 atm and 25 °C such that the combustion gases enter the reactor at a temperature of approximately 210 °C; c] introducing biol into the reactor at a temperature of 25 °C at a rate of 50 ml / min; and d] cooling the obtained granules by circulating air at room temperature.

8. The method of claim 7, characterized in that the static reactor is associated with a combustion equipment consisting of a modified burner whose flame provides approximately 5 kW of thermal energy to evaporate the liquid from the biol.

9. The method of claim 7, characterized in that the particles constituting granulation nuclei are selected from zeolite, dolomite and agricultural gypsum.

10. The method of claim 9, characterized in that the particles constituting granulation nuclei are zeolite.

11. The method of claim 9 or 10, characterized in that the particle size is between 2 and 4 mm.

12. A solid biofertilizer obtained by the process of any of the preceding claims 7 to 11, characterized in that it comprises particles consisting of granulation cores coated with biol, wherein the biol is incorporated into the zeolite in 70 - 75% by weight of the mass of biol.

13. A process for producing solid biofertilizer from liquid bio digestion waste characterized in that it comprises the steps of: a) loading a dynamic reactor with particles constituting granulation nuclei, where the reactor rotates at approximately 2 rpm and is grounded; b] introducing biol into the reactor at a temperature of 25 °C by atomizing it with a peristaltic pump at a rate of 50 ml / min from a biol storage tank with an air flow rate of 10 1 / min;c] generating electrical discharges with at least three electrodes inside the dynamic reactor, where the electrodes have different lengths such that the discharges are distributed inside the reactor, such that the temperature inside the reactor rises to 60 °C; and d] cooling the obtained granules by circulating air at room temperature.

14. The method of claim 13, characterized in that the particles constituting granulation nuclei are selected from zeolite, dolomite and agricultural gypsum.

15. The method of claim 14, characterized in that the particles constituting granulation nuclei are zeolite.

16. The method of claim 13 or 14, characterized in that the particle size is between 2 and 4 mm.

17. A solid biofertilizer obtained by the process of any of the preceding claims 13 to 16, characterized in that it comprises particles consisting of granulation cores coated with biol, wherein the biol is incorporated into the zeolite in 80 - 85% by weight of the mass of biol.

18. A procedure for producing solid biofertilizer from liquid bio digestion waste characterized in that it is carried out by combining the rotating dynamic reactor equipment with electrical discharges with a static reactor equipment with the entry of a flow of combustion gases from the burner, allowing the exhaust gases to be injected into the rotary reactor as the electrical discharges occur inside the reactor, reducing the electrical cost due to the consumption of plasma power and reusing the remaining energy of the combustion gases.

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