Aerobic particle bioreactor

Abstract

The present invention describes a bioreactor and a continuous flow process for water treatment and biomass production wherein the bioreactor comprises a tank (2) having an inlet (5) and an outlet (6), an aeration medium (7) and also a diversion medium (13) configured to extract clarified water and to prevent leakage of particulate biomass (11) at a decantation speed of at least 10 m / h, comprising a hollow body (14), the body has: a first inlet (15) at the bottom thereof configured to allow the entry of an aqueous fluid (9) and to return particulate biomass (11) to the tank (2); a second opening (16) laterally connected to the outlet (6) of the tank (2); and a third opening (17) located at the top and configured to allow air bubbles (10) to exit.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and in particular relates to treatment equipment for sewage treatment, drinking water treatment and biodegradable industrial wastewater treatment. Background Art

[0002] Pollution caused by wastewater discharge into the environment is a major environmental concern. Wastewater contains a wide variety of chemical and biological compounds that can impact natural ecosystems and / or human health, making their treatment prior to discharge a priority. Generally speaking, the composition of municipal wastewater can be defined according to Table 1.

[0003] Table 1: Composition of standard municipal sewage

[0004] waste Concentration (mg / L) Total solids 700-800 -Total dissolved / suspended / sedimentable matter 450-550 / 150-250 / 5-15 <![CDATA[DBO5]]> 200-300 COT 150-170 COD 300-600 Total nitrogen 40-80 -Organic nitrogen / free ammonia 15-30 / 25-50 Total phosphorus 8-16 -Organic phosphorus / inorganic phosphorus 3-6 / 5-10 chloride 40-60 sulfate 25-35

[0005] The most widely used municipal wastewater treatment technology in the world is the activated sludge bioreactor-based technology.

[0006] Over their 100-year history, these technologies have undergone numerous improvements in an attempt to increase their efficiency in removing organic matter, phosphorus, and nitrogen, while reducing the space required for their installation and the economic costs incurred by the process.

[0007] The activated sludge biological purification system (also called activated sludge) consists in cultivating bacteria in a stirred, aerated and sewage-fed tank, enabling them to metabolize the biological pollutants present in the sewage as nutrients.

[0008] It allows the elimination of various polluting substances through natural biological processes carried out by various microbial groups responsible for purification, with the subsequent removal of the resulting biomass from the water through sedimentation.

[0009] However, the large amount of biomass produced in the form of sludge and the high energy consumption of pumping circulating water, which accounts for about 50% of the total treatment cost, lead to a significant increase in treatment costs and the generation of large amounts of sludge that require proper treatment and is costly.

[0010] Furthermore, increasingly stringent restrictions on the quality of treated municipal wastewater, such as EU Directives 271 / 91EU and 98 / 15 / EC, have necessitated modifications to conventional activated sludge systems to address problems associated with nitrogen-induced eutrophication in certain regions.

[0011] During the past decade, there has been a great deal of interest in the treatment of domestic and industrial wastewater by using technologies based on aerobic granular systems.

[0012] Aerobic granular biomass operates under aerated conditions, i.e., in the presence of oxygen. It is particularly useful for treating high organic loads and removing nitrogen and phosphorus. Currently, aerobic granular biomass is produced in sequencing batch aerobic systems fed with wastewater, based on four operating phases: aeration, biomass decantation, treated water discharge, and contaminated water filling. These phases allow for the production of efficient biofilms for water treatment.

[0013] Aerobic granulation allows for better biomass retention due to a decantation stage before the treated water is discharged. This allows for the selection of biomass with greater decanting capacity, which prevents biomass from being lost with the effluent during discharge. Compared to activated sludge, this results in better settling capacity, lower sludge recirculation requirements, and greater resistance to sudden changes in influent and toxic compounds.

[0014] Granular biomass is composed of a diverse array of microorganisms responsible for eliminating pollutants present in wastewater. However, among all the existing microorganisms (heterotrophic, denitrifying, nitrifying, etc.), some exhibit enhanced growth capabilities in granular biofilm systems, particularly Comamonas, Zooglea, and Pseudomonas. These microorganisms can achieve greater compaction and stability through the production of exopolysaccharides (EPS).

[0015] The layered structure of granular biomass allows for the realization of aerobic and anaerobic zones within the biomass. This allows for multiple biological processes such as nitrification, denitrification, phosphorus removal, and organic matter removal to proceed simultaneously in a single bioreactor under aerated conditions.

[0016] Aerobic granulation is currently an alternative technology for water treatment, and many treatment plants in Europe (primarily for industrial wastewater) have integrated this system into sequencing batch bioreactors (BGS). Therefore, BGS is a technology that can achieve the operating conditions required for granule formation (Isanta et al., 2015; González-Martinez et al., 2017; Liu et al., 2017, Munoz-Palazón, 2018).

[0017] BGS reactors operate using a continuous feed, aeration, sedimentation, and discharge sequence. This process is complex, requiring individual control of each step. Feeding and discharge are particularly problematic because they must be performed within a short timeframe, requiring pumping systems and radical changes in operating conditions.

[0018] Aerobic granulation is advantageous in BGS due to the decanting process before discharge and the circulation within the bioreactor, which does not result in biomass loss. Although recently developed BGS systems attempt to simplify system operation by performing the filling and discharge phases simultaneously, this problem remains a technical obstacle. Regardless, the filling and discharge times in BGS reactors remain an inherent operational disadvantage of these systems (Pronk et al., 2015).

[0019] Therefore, the use of sequencing batch reactors will be limited to sites that produce low flow rates, as running multiple BGSs in parallel or installing equalization tanks to handle higher influent flow rates is considered an impractical alternative.

[0020] However, in recent years, there has been growing interest in developing continuous-flow granular bioreactors (BRFCs) (Chen et al., 2017; Xin et al., 2017; Corsino et al., 2016; Qian et al., 2017).

[0021] It is estimated that the application of this technology can treat high-flow wastewater, such as wastewater treated in urban water purification systems serving more than 20,000 equivalent residents in large cities.

[0022] Unlike BGS reactors, BRFCs offer the advantages of better control and simpler operation during the purification process (Corsino et al., 2016; Qian et al., 2017). Conversely, they can also be used within existing infrastructure in currently operating conventional activated sludge treatment plants, which operate in a continuous flow mode due to the large influent volumes they treat.

[0023] To this end, the use of reactors with dividing vanes defining a first aerated zone and a second non-aerated zone has been described, as has the use of other designs such as concentric tubes with a central aerated zone and an outer non-aerated zone.

[0024] However, in current BRFC systems, the elimination of the decantation stage and the possible loss of biomass due to the continuous output of treated water, which manifests itself in a negative impact on the compaction and stability of the particles, make it impossible to use such systems for long-term continuous treatment of water flows.

[0025] In summary, these systems have significant operational limitations:

[0026] -BGS reactor needs to work at a low operating rate,

[0027] -BGS reactors require a high degree of automation due to their batch mode operation,

[0028] - Existing BRFC reactors have high biomass losses,

[0029] - Unable to process continuously for a long time,

[0030] - Lack of stability and compaction of aerobic granules in BRFC reactors,

[0031] -BRFC system has high efficiency loss.

[0032] To overcome the limitations of existing bioreactors in water treatment, new equipment has been proposed. Summary of the Invention

[0033] The present invention describes a continuous flow bioreactor for forming aerobic granular biomass and treating drinking water and wastewater, both municipal and industrial.

[0034] The present invention solves the problems of the prior art in continuous wastewater treatment by enabling the formation of long-term stable particles. Thus, unlike current continuous flow bioreactor solutions, the formation of these particles enables these systems to be used for water treatment in a continuous and stable manner over time.

[0035] To achieve stable pelletization, the present invention describes a novel bioreactor configuration that can be operated under operating conditions that allow for optimized biomass development. The operating conditions are shown in Table 2 below.

[0036] Thus, aeration in the range of 0.5-15 mg of oxygen per liter makes it possible to generate biomass movement within the bioreactor, thereby compacting the biomass until a granular structure is formed, wherein said compaction allows anaerobic processes to be achieved inside the granules. On the other hand, the pH range (6-9) and temperature (15-30° C.) used are optimal for the growth of microorganisms that favor granule formation. Finally, the hydraulic retention time determined is the time required to achieve a sufficient concentration of biomass to be able to eliminate the desired pollutants in the wastewater, as provided for, for example, in European Directive 91 / 271 / EEC.

[0037] Table 2: Operating conditions of BRFC reactor

[0038] Running status quantity pH 6-9 Aeration (mg oxygen per liter) 0.5-15 Hydraulic retention time (hours) 2-24 Temperature (℃) 5-45

[0039] In contrast to sequencing batch particle reactors that undergo decanting, draining, and filling stages for biomass formation and water treatment, the present invention features a continuously flowing water stream feed. In this way, a significant improvement in the system is achieved by eliminating the need for some of these stages.

[0040] In this sense, the present bioreactor promotes the stabilization of multicellular contacts caused by initial attractive forces such as physical forces (van der Waals forces, surface tension, etc.), chemical forces, and biochemical forces.

[0041] To this end, the bioreactor comprises a tank for accumulating a water flow, the tank having a bottom and a wall surrounding the bottom, an inlet for influent water, preferably sewage, and an outlet for clarified effluent water.

[0042] Furthermore, the bioreactor includes an aeration device configured to introduce air into the bioreactor vessel. Thus, the air inlet serves two functions. On the one hand, it provides the necessary oxygen for microbial development, and on the other hand, it generates physical motion of a convective nature, which facilitates contact between bacteria in the fluid through the diffusive hydrodynamic processes of cell mobility and mass transfer.

[0043] Due to the presence of the aeration medium, the bioreactor thus has an upward air flow, which is preferably in the form of bubbles, in the range of 0.5 to 15 mg of oxygen per liter. More preferably, it is in the range of 2 to 15 mg of oxygen per liter or 2 to 4 mg of oxygen per liter. This configuration is the most efficient for obtaining granular biomass for two main reasons:

[0044] 1.- As air bubbles always tend to rise in water, oxygen diffuses from the air bubbles into the water over a greater area for aerobic processes. This reduces air pumping requirements and therefore costs.

[0045] 2.- The ascending aeration prevents the biomass from settling at the bottom (which would prevent the formation of granular biomass), thus allowing to keep the biomass in constant motion for the formation of granular biomass.

[0046] Thus, without this upward flow, the granular biomass of the sludge would tend to sink to the bottom of the tank, while the suspended particles would remain in the fluid. By introducing an upward fluid flow, it will result in the formation of a fluidized bed where the particulate matter has an upward force tending to carry them towards the top.

[0047] However, the granular particles are preferably of a size in the range of 1-40 mm in diameter and are arranged so that they are not sufficiently disturbed by the aeration flow and will sink against the aeration flow under their own weight, while the flocs (particles suspended in the fluid) are moved by the aeration effect itself and separated by the top of the tank.

[0048] The present invention thus makes it possible to maintain the granulated biomass in the tank so as to carry out the granulation process while removing excess biomass that is not required for the granulation process.

[0049] Depending on the air flow, the residence time of the particles inside the tank can be controlled, resulting in a correctly stabilized particle process.

[0050] However, the pelletization process is a gradual process and therefore the biomass may initially be of smaller size where the aeration effect of the tank is relevant and pushes it to the top of the tank, resulting in a loss of the desired biomass in the tank.

[0051] To avoid this effect and the consequent loss of biomass as in other solutions in the prior art, the bioreactor comprises a flow conducting medium connected to the outlet of the bioreactor tank.

[0052] The flow medium is configured to restrict the outflow of particulate biomass, i.e., it operates as a particle trap, wherein if any particles are introduced into the flow medium, they tend to return to the bioreactor tank. To this end, the flow medium comprises a hollow body with three openings.

[0053] The flow-guiding medium includes a first opening, or first inlet, or primary inlet, at its bottom. This inlet is positioned to discourage the entry of particulate biomass, as such particles tend to settle easily. Specifically, the first inlet is configured to admit a treated water stream with a reduced concentration of particulate biomass into the main body. It is also configured to return decanted particulate biomass to the bioreactor tank if it enters the flow-guiding medium.

[0054] On the other hand, the second opening or second outlet of the flow guide medium is connected to the outlet of the bioreactor tank. The second opening is preferably located at the side. Therefore, the effluent leaving the flow guide medium is a treated water flow containing the flocs present in the fluid.

[0055] Finally, a third opening is located at the top of the baffle medium. The baffle medium is immersed in the fluid within the bioreactor tank. Preferably, the top portion is level with or above the water level to prevent particles from escaping, i.e., entering the baffle medium through the third opening. The function of the top opening is to allow any air bubbles that enter the baffle medium to escape, thereby preventing their accumulation, which would make it difficult for the treated water to exit the bioreactor. Preferably, the third opening completely occupies the upper portion of the hollow body. This prevents the presence of a surface on which a biofilm could form, potentially blocking the baffle medium outlet.

[0056] Thus, the bioreactor described in the present invention comprises a flow-guiding medium having a hollow body, wherein the hollow body comprises:

[0057] a first inlet, located at the bottom of the body, configured to allow fluid to enter the interior of the body and return decanted granular biomass to the tank;

[0058] A second opening, located on the side of the body, connected to the outlet of the aerobic bioreactor; and

[0059] • A third opening, located at the top of the body, is configured to allow air bubbles to escape.

[0060] Thus, unlike other current bioreactors, this flow medium can act as a separator between the processed fluid and the particulate biomass. The presence of a flow medium as described in the present invention means that a bioreactor with this flow medium can operate with continuous feed and discharge flow, reducing biomass loss within the tank and improving the stability of the bioreactor over time.

[0061] In short, the flow director is configured so that the biomass exiting the bioreactor does not reach a settling velocity exceeding 10 m / h, which is the desired velocity considered optimal for granular biomass formation.

[0062] In this way, under continuous feed flow, it is possible to maintain granular biomass within the BRFC bioreactor while allowing excess biomass to be discharged. By extending the residence time of the biomass in the tank, the maturation of cell aggregates is promoted by the production of extracellular polymeric substances, thus forming granular biomass and achieving an optimal decanting rate.

[0063] All of this means that the BRFC bioreactor of the present invention allows for the advantages of granular systems, such as achieving significantly higher biomass concentrations and yields than conventional activated sludge systems, and can operate in a continuous flow configuration, rather than the batch mode used in other granular reactors used in wastewater treatment. Thus, by eliminating flocs that compete for the same nutrients, the growth of granular biomass within the BRFC reactor is favored, allowing the granular aerobic sludge to gradually accumulate in a continuous state.

[0064] The result of this configuration is the formation of granular biomass at the bottom of the tank and the production of continuous treated wastewater.

[0065] In a second aspect of the present invention, a method developed in a bioreactor according to the present invention may be defined, the method comprising the following steps:

[0066] - continuously feeding and accumulating feed water in the bioreactor tank, wherein the bioreactor tank has an air flow rate in the bioreactor tank in the range of 0.5-15 mg oxygen per liter, a hydraulic retention time of 2-24 hours, a pH between 6 and 9, and a temperature between 5-45° C.;

[0067] - Inoculation of microorganisms and formation of granular biomass in a bioreactor tank;

[0068] - separation of particulate biomass and treated water within the diversion medium; and

[0069] -Continuously output clear water.

[0070] Thus, due to the bioreactor of the invention, preferably, in a stable manner over time, a granular biomass is formed having a decanting velocity of more than 10 m / h and a biomass concentration of up to 30 g / L, preferably in the range of 1-20 g / L.

[0071] On the one hand, and in contrast to current solutions, the decanting rate of the biomass formed in the bioreactor of the present invention obviates the need for high sludge recirculation in secondary decanting tanks, as occurs in conventional purification systems, in order to maintain an optimal bacterial concentration. Furthermore, a greater compaction of the formed biomass is achieved, which manifests itself in the ability to produce a greater amount of biomass per liter, thus allowing aerobic and anaerobic processes to be carried out in the same bioreactor.

[0072] On the other hand, the bioreactor according to the present invention has an outlet at the top. This makes it possible to contain granular biomass throughout the bioreactor volume, resulting in a significant increase in biomass per liter. In other words, thanks to this solution, a greater number of bacteria is achieved within the system, resulting in a much higher pollutant removal performance of over 95%.

[0073] Because biomass losses in the bioreactor are lower compared to other bioreactors, there is no need to decant biomass in the second bioreactor and reintroduce it into the initial bioreactor, enabling the reactor to operate in continuous mode for extended periods. Consequently, the bioreactor of the present invention allows for a reduction in required volume by increasing the purification rates achieved in traditional activated sludge systems, potentially reducing the volume of an equivalent bioreactor by up to 50%. Conversely, the continuous configuration of the present bioreactor increases the amount of water processed per unit time by 50% compared to a BGS reactor. Furthermore, the present invention avoids continuous biomass losses from the bioreactor, enabling stable operation over time.

[0074] Therefore, from an economic point of view, the present invention improves the sustainability and competitiveness of the water treatment industry, as the quality of the effluent is improved through more efficient and cost-effective treatment, achieving a reduction of more than 50% in recycling energy consumption. The present invention achieves acceptable yields in water treatment, achieving a reduction of up to 80% in nitrogen and up to 90% in organic matter.

[0075] Compared with other existing systems, the advantages of the present invention are worth mentioning as follows:

[0076] - Ability to handle large traffic volumes.

[0077] - No decanting means are required before discharging the bioreactor.

[0078] -The size of the bioreactor is smaller.

[0079] - Improved process efficiency.

[0080] - Increased amount of biomass per unit volume of the bioreactor.

[0081] - Granular biomass grows throughout the volume of the bioreactor.

[0082] -Stable operation over time.

[0083] These results demonstrate how this system is a viable alternative to current water treatment system solutions.

[0084] This can manifest itself in economic benefits for companies through increased profits and the release of economic resources, and in increased employability through the creation of new jobs with higher qualifications.

[0085] The following elements are shown in the figure:

[0086] 1. Bioreactor

[0087] 2. Cans

[0088] 3. Bottom of the tank

[0089] 4. Tank wall

[0090] 5. Tank entrance

[0091] 6. Tank outlet

[0092] 7. Aeration medium

[0093] 8. Diffuser

[0094] 9. Water-based fluids

[0095] 10. Bubbles

[0096] 11. Granular biomass

[0097] 12. Flocculent

[0098] 13. Diversion medium

[0099] 14. Subject

[0100] 15.First Import

[0101] 16. Second opening

[0102] 17. The third opening

[0103] 18. Protrusion

[0104] 19. Side hole

[0105] Throughout the specification and claims, the word "understands" and its variations are not intended to exclude other technical features, components or steps. In addition, the word "comprising" includes the case of "consisting of..." For those skilled in the art, other objects, advantages and features of the present invention will be revealed in part from the specification and in part from the practice of the present invention. The following examples and drawings are provided as illustrations and are not intended to limit the present invention. In addition, the present invention covers all possible combinations of the specific and preferred implementations indicated herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] Figure 1 One implementation of a continuous flow bioreactor is shown.

[0107] Figure 2 A front view of one embodiment of a bioreactor flow guide medium is shown.

[0108] Figure 3 A plan view (plant) showing one embodiment of a bioreactor flow medium.

[0109] Figure 4 A comparison chart showing the results of the continuous flow bioreactor according to the present invention (BRFC1) and other existing solutions (BRFC2 and BRFC3) showing the change in granular biomass concentration (CBG) in g / L over time (t) in days. DETAILED DESCRIPTION

[0110] The present invention describes a continuous-flow bioreactor 1 for water treatment by forming aerobic granular biomass. The water to be treated can include both municipal and industrial drinking water or sewage influent. Therefore, to achieve both water treatment and granular biomass formation within a bioreactor tank operating in continuous flow, the bioreactor requires a specific configuration.

[0111] therefore, Figure 1 One embodiment of a continuous flow bioreactor 1 is shown.

[0112] The continuous flow bioreactor 1 according to the present invention comprises a tank 2 configured to treat an aqueous fluid 9 therein. The tank 2 has a bottom 3 and a wall 4 arranged around the bottom 3. The tank 2 also has an inlet 5 for influent, preferably sewage to be treated, and an outlet 6 for clarified effluent, which contains flocculants 12 and a small amount of particulate biomass 11. Preferably, the inlet is located in the portion of the tank 2 furthest from the outlet, so that the influent, laden with pollutants, is homogenized within the tank and treated before exiting. In a preferred embodiment, the inlet 5 is located at the bottom of the tank 2, near the bottom 3, while the outlet 6 is located at the top, as far away from the inlet 5 as possible.

[0113] Furthermore, the bioreactor 1 comprises an aeration medium 7 configured to introduce gas bubbles 10 into the tank 2 of the bioreactor 1. In a preferred embodiment, the bioreactor 1 has an upward air flow in the form of bubbles. To this end, the aeration medium 7 may comprise a diffuser 8, for example in the form of a porous plate, which evenly distributes the gas bubbles 10.

[0114] However, the granulation process requires a certain residence time of the biomass in the tank 2. To prevent the loss of biomass in the tank 2, the bioreactor 1 includes a flow medium 13 connected to the outlet of the tank 2 of the bioreactor 1, and the flow medium is configured to extract clarified water and prevent the granulated biomass 11 from flowing out at a decantation velocity of at least 10 m / h.

[0115] like Figure 1 As shown, the guiding medium 13 is submerged in the top of the tank 2 , preferably at the same height as the water level or above the water level, which can prevent the granular biomass 11 from being placed above the guiding medium 13 .

[0116] Furthermore, in another preferred embodiment, the flow medium is positioned away from the flow of bubbles 10 generated in the aeration medium 7. This reduces the ingress of granular biomass 11 into the flow medium 13, allowing this type of biomass to remain in the tank 2 for a sufficient time to form granules.

[0117] Unlike solutions known in the prior art, the ability to keep the biomass inside the bioreactor tank 2 until granular biomass 11 is formed in this solution avoids biomass losses, so it can be used stably as a continuous flow bioreactor over time.

[0118] In this sense, Figure 2 A preferred embodiment of the flow conducting medium 13 of the bioreactor 1 is shown in a front view.

[0119] like Figure 2 As shown, the body 14 is hollow and includes three openings 15, 16 and 17 through which aqueous fluid can pass:

[0120] A first opening or inlet 15, located at the bottom of the body 14, is configured to allow the aqueous fluid 9 to enter the body 14. Furthermore, it is configured to return the granular biomass 11 to the interior of the tank 2 if the granular biomass 11 enters the interior of the flow conducting medium.

[0121] A second opening 16 or outlet, located on the side of the body 14. This second opening 16 is connected to the outlet of the tank 2 of the bioreactor 1 .

[0122] A third opening, located at the top of the body 14 , is configured to allow the air bubbles 10 to escape.

[0123] A first inlet 15 allows aqueous fluid 9 to enter the main body 14 of the flow-guiding medium 13. This fluid 9 contains various particulate materials, including granular biomass 11 and flocs 12, which can be moved within the fluid by aeration. These particulate materials differ in the decanting ability of the granular biomass 11. Specifically, granular biomass 11 can refer to microorganisms with a decanting velocity of at least 10 m / h. Because granular biomass 11 tends to settle, this inlet is positioned in the lower portion of the flow-guiding medium 13, opposite the direction of entry for the granular biomass 11.

[0124] On the other hand, the second opening 16 is connected to the outlet 6 of the tank 2 and is preferably arranged laterally, and even more preferably, high up in the main body 14, to facilitate the separation of the granular biomass 11. This reduces the impact of aeration in the area where the flow-guiding medium 13 is located. Furthermore, existing tank infrastructure, such as that found in conventional treatment plants, can be utilized. Due to the large influent volumes being treated, these tanks operate in a continuous flow mode, thus providing an acceptable device for the present invention. While reusing existing structures can reduce costs, these tank structures would require modification to accommodate the addition of the aeration medium 7 or flow-guiding medium 13.

[0125] Finally, a third opening 17 is located at the top of the body 14. Its main function is to allow the escape of gas bubbles 10 that have entered the flow-guiding medium 13. The possibility of escaping these gas bubbles 10 present in the flow-guiding medium 13 means that an area with reduced upward aeration is created within the tank 2. Thus, the hollow volume in the body is an ideal space for decanting the granular biomass 11.

[0126] In a preferred embodiment, the flow medium 13 has a main body 14 in the shape of an inverted truncated cone. As described above, this shape facilitates the return of particulate biomass 11, introduced into the flow medium 13 by aeration, to the tank 2 with a region free of gas bubbles 10. The main body 14 has a volume that allows for the separation of the particulate biomass 11. Furthermore, the particulate biomass 11 is preferably returned to the tank 2 without the formation of a biofilm within the flow medium 13. Thus, the truncated cone shape provides an acceptable central space for biomass separation and allows the particulate biomass 11 to roll through the walls of the first inlet 15, which preferably has a reduced diameter compared to the main body 14.

[0127] The first inlet 15 has a side hole 19 parallel to the upward flow of air bubbles 10. In a preferred embodiment, the side hole 19 is oriented toward the wall of the tank 4, thereby reducing the influence of the upward aeration flow. Figure 2 As shown, the first inlet 15 connects the body 14 to the side aperture 19 .

[0128] For its part, the first inlet 15 at the bottom of the flow conducting medium 13 prevents the granular biomass 11 from rising to the higher area where the second opening 16 of the flow conducting medium 13 is located and to the outlet 6 of the tank 2 due to its decanting properties.

[0129] To improve this restriction of the inlet of the granular biomass 11 , in another embodiment, the first inlet 15 may have an additional protrusion 18 that redirects the first inlet 15 .

[0130] However, despite the improved configuration of the flow guide medium 13, in the event that some particles of the granular biomass 11 enter the flow guide medium 13, the body 14 of the flow guide medium itself is configured to allow the particles to return (by gravity) to the tank of the bioreactor, while the flocs 12 with a lower decanting rate will not be able to return to the tank 2 and will reach the outlet 6 of the tank 2 through the second opening 16.

[0131] Figure 3 A plan view of an embodiment of a flow conducting medium 13 of a bioreactor 1 is shown. Figure 3 , details are shown of how the third opening 17 covers the entire surface of the upper portion of the body 14. This configuration, in addition to allowing the escape of air bubbles 10, also promotes cleanability within the flow guide medium 13. An alternative approach of partially covering the flow guide medium 13 to allow the escape of air bubbles 10 may be operationally feasible, preventing the ingress of foreign matter through the upper portion of the flow guide medium 13. However, the presence of such a surface creates the potential for biofilm accumulation, which may reduce the performance of the bioreactor 1.

[0132] The outflow from bioreactor 1 is a clarified water stream containing the flocculants 12 present in the fluid, but with a minimal concentration of particulate biomass 11. From a higher perspective of this embodiment, it can be seen that the diameter of first inlet 15 at the bottom is smaller than the volume within body 14 of flow guide medium 13. First inlet 15 is the location through which particulate biomass 11 emerges once aeration is suppressed.

[0133] In short, the flow conducting medium 13 is configured for the biomass to be discharged from the bioreactor 1 without reaching a higher decanting velocity of 10 m / h, which is considered to be the optimal velocity for forming the granular biomass 11 .

[0134] In this way, the granular biomass 11 can be maintained inside the BRFC bioreactor under a continuous feed flow while allowing excess biomass such as flocs 12 to drain away, thereby fostering the formation of granular biomass while treating the water stream.

[0135] In a second aspect of the present invention, a water treatment method is described. The water treatment method employed has the following stages:

[0136] - allowing the influent to continuously enter and accumulate in the bioreactor tank 2,

[0137] - inoculating microorganisms in the bioreactor tank 2 and forming granular biomass 11,

[0138] -Continuous output of clarified water effluent.

[0139] Therefore, according to the method for water treatment by forming granular biomass according to the present invention, purified effluent water is obtained as a result of the metabolism produced by the microbial population present in the granular biomass 11 formed in the bioreactor 1.

[0140] Feeding of the feed water to tank 2 can be done by pumping or gravity, so that a constant feed can be provided based on the feed water inlet flow rate that needs to be treated.

[0141] Aeration in the bioreactor 1 is performed at the bottom using an aeration medium 7, preferably a diffuser 8, such as a porous plate. When located in the lower region of the bioreactor 1, the aeration medium 7 allows the granular biomass 11 to be kept in continuous motion, resulting in granule formation.

[0142] Specifically, the amount of air in the tank is in the range of 0.5-15 mg of oxygen per liter. It is preferably in the range of 0.5-8 mg of oxygen per liter, and more preferably in the range of 2-4 mg of oxygen per liter. This air flow provides sufficient oxygen for all aerobic processes required to remove pollutants from the sewage.

[0143] In addition to the air supply, other factors must be controlled for the biomass formation process to proceed properly. In a preferred embodiment, the water stream is accumulated at a pH between 6 and 9, even more preferably between 6.5 and 8. Furthermore, the temperature during the granulation process is between 5 and 45°C, preferably between 15 and 25°C. Adopting these conditions can affect the behavior of the inoculated microorganisms, thereby reducing the performance of the water treatment process.

[0144] For proper water treatment, an anaerobic process is also required. The formation of granular biomass 11 is absolutely necessary for this anaerobic process to occur, as it occurs in the interior of the granules. Furthermore, the formation of granular biomass 11 is crucial for increasing the concentration of microorganisms within the system.

[0145] On the other hand, thanks to this solution, all biomass present in the bioreactor 1, not in the form of granular biomass 11, is prevented from multiplying when it leaves the bioreactor 1 along with the effluent through the outlet, thus reducing or even preventing the proliferation of microorganisms that could alter the performance of the system. In other words, the microorganisms present in the flocs 12, i.e., those that compete with the granular biomass 11 for the available nutrients, are eliminated in the flow out of the bioreactor 1.

[0146] Therefore, for water treatment, it is necessary to form granular biomass 11 with an appropriate microbial population capable of eliminating all pollutants. Among the microbial populations used for water treatment, it is worth mentioning: ammonium oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB), ammonium oxidizing archaea (AOA) and phosphate accumulating organisms (PAO).

[0147] Biomass retention is a fundamental stage in the process. It defines the water treatment and the formation of activated sludge containing granular biomass 11, allowing time for the microbial action to take place.

[0148] Thus, unlike other existing solutions in this field, the result of this stage is that granular biomass 11 can accumulate in the activated sludge at a decantation rate greater than 10 m / h, allowing the solution to be used in a stable manner over time to purify a continuous flow of contaminated water.

[0149] Example 1 - Variation of residence time

[0150] Example 1 illustrates an example of a method for water treatment by forming granular biomass in a bioreactor according to the present invention. The bioreactor has a capacity of 6 L and is fed with a continuously flowing water stream. The stream is aqueous and has the composition shown in Table 3.

[0151] Table 3. Composition of wastewater used to obtain pellets

[0152] Compound Concentration (g / L) <![CDATA[CH3COONa·3H2O]]> 0.79 <![CDATA[NH4Cl]]> 0.25 KCl 0.04 <![CDATA[MgSO4·7H2O]]> 0.10 <![CDATA[K2HPO4]]> 0.085 <![CDATA[KH2PO4]]> 0.03

[0153] The inoculation of the microorganisms was carried out using activated sludge from a sewage treatment plant. A pH value of 7, an aeration of 6 mg of oxygen per liter and a temperature of 22° C. were used to create optimal conditions for the development of the microorganisms used in this example.

[0154] In this sense, Table 4 below shows the results of granular biomass concentration (CBG), decantation rate (VD), organic matter removal performance (RMO) and total nitrogen removal performance (RNT) obtained by changing the hydraulic retention time (HRT) in 6 samples using the system of the present invention.

[0155] Table 4. Results according to residence time

[0156] sample TRH(h) CBG (g / L) VD(m / h) RMO (%) RNT (%) Sample 1 24 4.7 33 99 99 Sample 2 16 4.9 33 99 96 Sample 3 8 8.2 35 99 87 Sample 4 6 8.1 39 97 77 Sample 5 4 6.2 28 96 70 Sample 6 2 5.8 20 92 61

[0157] Example 2 - Temperature Change

[0158] In the same bioreactor as in Example 1, the bioreactor was inoculated with a hydraulic retention time of 8 hours and operated at variable temperatures. According to Table 5, it can be observed that the performance decreases when the temperature drops to a level below 10°C.

[0159] Table 5. Results according to temperature changes

[0160] Temperature (℃) RMO (%) RNT (%) Sample 7 30 99 89 Sample 8 20 93 82 Sample 9 10 80 47 Sample 10 5 60 26

[0161] Example 3 - Evolution over time

[0162] Three continuous flow granular bioreactors (BRFC1, BRFC2 and BRFC3) of different designs were inoculated with the same activated sludge and operated under the same conditions. In this sense, the operating conditions adopted were an aeration of 6 mg oxygen per liter, a temperature of 22°C, a pH of 7 and a HRT of 8 hours.

[0163] The different continuous flow bioreactor (BRFC) models used are as follows:

[0164] BRFC1: is a reactor according to the invention, comprising a flow guide medium 13 connected to the outlet of the bioreactor, which allows the sedimentation of particles in the outlet area;

[0165] - BRFC2: a reactor comprising a plate dividing the bioreactor into two parts, thereby creating a first aerated and particle rising zone and a second non-aerated and particle falling zone where the water outlet is located; and

[0166] -BRFC3: A reactor consisting of two zones, inner and outer, defined by two concentric tubes. The inner zone is defined by the interior of the concentric tube with the smaller radius, where aeration is introduced, lifting the particles. The particles descend again through the outer zone, where there is no aeration. The outer zone is defined by the annular space between the two tubes, where the water outlet is located.

[0167] like Figure 4 As shown, the yield of the water treatment remains stable over time (t: days), thus confirming its improvement compared to other solutions, in which the loss of granular biomass concentration (CBG: g / L) makes them unusable in continuous flow, requiring the constant addition of new biomass. In this sense, it can be observed how the biomass yields achieved by the alternative designs of previously developed continuous flow bioreactors, namely BRFC2 and BRFC3, are far lower than the biomass yield achieved by the bioreactor BRFC1, which is the reactor according to the present invention.

Claims

1. A continuous flow bioreactor configured for water treatment, comprising: - a tank (2), comprising a bottom (3) and a wall (4) surrounding the bottom (3), configured to treat an aqueous fluid (9) therein; - an inlet (5) for water inlet and an outlet (6) for water outlet; and - an aeration medium (7) configured to introduce gas bubbles (10) into the tank (2); Characterized in that the bioreactor also includes: - a flow guiding medium (13) configured to extract clarified water and prevent leakage of the granular biomass (11) having a decantation velocity of at least 10 m / h, the flow guiding medium comprising a hollow body (14), wherein the hollow body (14) comprises: a first inlet (15), located at the bottom of the body (14), configured to allow the aqueous fluid (9) to enter the body (14) and return the granular biomass (11) to the tank (2); a second opening (16) located on the side of the body (14) connected to the outlet (6) of the tank (2); and The third opening (17), located at the top of the body (14), is configured to allow the air bubbles (10) to escape.

2. The aerobic bioreactor according to claim 1, wherein the flow conducting medium (13) has a frustoconical shape.

3. The aerobic bioreactor according to any one of claims 1 to 2, wherein the third opening (17) of the flow guiding medium (13) covers the entire surface of the upper portion of the main body (14).

4. An aerobic bioreactor according to any one of claims 1 to 3, wherein the first inlet (15) has a side hole (19) parallel to the upward flow of gas bubbles (10).

5. An aerobic bioreactor according to any one of claims 1 to 4, wherein the body (14) of the flow-guiding medium (13) comprises a protrusion (18) connected to a first inlet (15), the first inlet comprising a side hole (19) parallel to the wall (4) of the tank (2), configured to allow the aqueous fluid (9) to enter the body (14) and return the granular biomass (11) to the tank (2).

6. The aerobic bioreactor according to any one of claims 1 to 5, wherein the aeration medium (7) is located at the bottom (3) of the tank (2).

7. The aerobic bioreactor according to any one of claims 1 to 6, wherein the aeration medium (7) comprises a diffuser (8) configured to form air bubbles (10).

8. A method for water treatment by forming granular biomass in a bioreactor (1) according to any one of claims 1 to 7, characterized in that The method comprises the following steps: - continuously feeding and accumulating the influent into the bioreactor tank (2), wherein the tank (2) has an air flow rate in the range of 0.5-15 mg oxygen per liter, a hydraulic retention time of 2-24 hours, a pH value between 6 and 9, and a temperature between 5-45°C; - inoculating microorganisms in the bioreactor tank (2) and forming granular biomass (11); - separation of the granular biomass (11) and the treated water within the flow conducting medium (13); and -Continuously output clear water.

9. The method according to claim 8, wherein the air inlet forms a bubble flow.

10. The method according to any one of claims 8 to 9, wherein the pH value is between 6.5 and 8.

11. A method according to any one of claims 8 to 10, wherein the air inlet flow rate is between 2-4 mg oxygen per litre.

12. The method according to any one of claims 8 to 11, wherein the temperature is between 15-35°C.

13. The method according to any one of claims 8 to 12, wherein the separation of the granulated biomass (11) is a decantation stage.

14. Granulated biomass (11) obtained according to the method of any one of claims 9 to 13.

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