Simultaneous stage anaerobic sequential batch reaction system equipped with batch degassing section and semi-continuous sedimentation section

Abstract

The present invention relates to a process for treating an aqueous fluid containing biodegradable organic matter, comprising: a bioreactor batch supply step in which the aqueous fluid to be treated is supplied into a bioreactor; a batch reaction step in which the aqueous fluid is treated by microorganisms and biogas is produced within the bioreactor; a degassing unit supply step in which an aqueous suspension containing the aqueous fluid treated by microorganisms and biomass is withdrawn from the bioreactor and batch supplied into a degassing unit; and a semi-continuous biomass separation unit supply step in which the degassing aqueous suspension is withdrawn from the batch degassing unit and supplied into a biomass separation unit.

Description

Technology Field

[0001] The present invention relates to a process for treating an aqueous fluid containing biodegradable organic material, comprising a batch reaction step in which the biodegradable organic material is converted by microorganisms to produce biogas (generally a gas mixture consisting mainly of methane and carbon dioxide). The present invention also relates to a sequential batch reaction system that performs simultaneous steps. Background Technology

[0002] A process for producing biogas from waste containing organic biomass in an anaerobic sequential batch reactor (AnSBR) was developed in the early 1990s. US 5185079 A relates to a single-vessel AnSBR operated by a cycle having four main stages: feed, reaction, settling, and decanting, and including a sludge removal stage as needed. Advantages of the AnSBR include a high level of process flexibility in terms of cycle time and sequence, the ability to operate without a purifier, and the ability to operate with a relatively simple apparatus. Additionally, the rich / poor conditions induced by sequential operation promote the decomposition of slow-degrading particulate substrates (suspended solids, oils, fats, and greases) and / or relatively difficult-to-handle compounds, and enhance bio-coagulation. Furthermore, this sequential operation leads to the formation of superior settling sludge due to natural selective pressures against inferior settling sludge. As a result, efficient solid separation is promoted, extending the solid retention time (SRT) and improving the efficiency of the conversion of organic substrates into methane and carbon dioxide.

[0003] Despite being developed a long time ago, the industrial use of AnSBR is limited. The main limitations of AnSBR are thought to be the incorrect application of the configuration, design errors, uncertainty in sludge settling control, and problems with managing batch volumes (fluid and gas) and the resulting need for large buffer tanks and gas storage devices.

[0004] Several development attempts to modify the composition of AnSBR to take advantage of the aforementioned benefits are known. For example, a process called "temperature-stepped AnSBR" has been proposed, in which two reactors are operated in series. The first reaction is carried out at a high temperature (55 °C) and the second reaction is carried out at a medium temperature (35 °C).

[0005] US 5,599,450 A relates to an anaerobic upward-flow batch reactor, which is another configuration developed for the AnSBR concept. This system aims to provide a plug flow through an anaerobic waste stream treatment reactor that evenly distributes the waste stream at the bottom of the reactor and collects the waste stream at the top to form an upward plug flow through the reactor during the filling, recycling, and decanting processes, and to minimize horizontal mixing. According to the inventors, this plug flow promotes the growth of heavier biomass near the bottom of the reactor where substrate concentration is highest and inhibits the growth of lighter biomass near the top of the reactor where substrate concentration is lowest.

[0006] While methods for treating aqueous waste containing organic biomass within an AnSBR offer various advantages, known systems also have inherent drawbacks. In the process described above, the reaction stage, where biogas is generated from organic biomass, and the sedimentation stage are performed sequentially. During the sedimentation stage, solids move toward the bottom of the reactor to form (concentrated) sludge, while a supernatant (an aqueous phase of the fluid, which has a low solid particle content relative to the fluid (suspension) and is preferably composed essentially of solid particles) is formed at the top of the reactor. After sufficient sedimentation, the supernatant is discharged from the reactor as effluent. To obtain a supernatant with a low solid particle content or essentially free of solid particles, a long sedimentation time is desirable, as this facilitates the downstream processing of the effluent. Therefore, given a cycle time, the duration of sedimentation becomes a limiting factor for the total decomposition capacity of organic matter and the biogas production capacity, as it reduces the time available for the reaction stage. Furthermore, as described above, the processes performed within the AnSBR are characterized by fluctuating biogas production rates. At the start of the process cycle (feeding stage), the biogas production rate gradually increases until it reaches a maximum (typically at or near the end of the feeding stage, or at the beginning of the reaction stage). After the biogas production rate reaches its maximum, the reaction stage continues until the rate reaches a lower critical threshold, after which the settling stage begins. During the settling stage, biogas production typically continues, but the production rate generally decreases further to a minimum (which may be zero) during the decanting stage (where emissions are discharged).Due to fluctuations in the biogas production rate, the biogas flow from the reaction system varies significantly, which is undesirable in terms of further processing the biogas stream downstream of the AnSBR and / or providing a continuous supply of biogas for future uses, such as energy production.

[0007] WO 2019 / 115034 discloses an improved process and facility for simultaneously converting organic matter by microorganisms within a bioreactor and settling solid particles in a treated fluid within another vessel, which allows for a more consistent flow of produced biogas effluent from the facility. This process comprises at least one additional step including (i) a bioreactor feed step, (ii) a batch reaction step in which biogas is generated and the generated biogas is temporarily stored in a separate vessel, and (iii) a settling step and / or an aqueous fluid discharge step, which utilizes the biogas stored in the separate vessel to reduce fluctuations in the biogas effluent from the facility. This configuration has currently undergone various tests on an industrial scale, and the construction of a full-scale system is scheduled to begin.

[0008] These processes and facilities offer significant advantages in terms of, for instance, CAPEX, OPEX, robustness, or resistance to fats in the feed. However, scaling up these processes / facilities complicates the design of the external vessel serving as the solid separation and degassing unit (e.g., biomass containing microorganisms used to generate biogas from biodegradable materials within the bioreactor). In this case, large volumes need to be handled, requiring large-diameter piping and high-capacity pumps to feed material into the external vessel and withdraw its contents within a short time. Furthermore, increasing processing capacity requires a larger vessel surface area and pressurization of the vessel for at least part of the process, which necessitates a flexible top section, thereby further complicating the design. A skilled technician can address this issue based on the disclosure of WO 2019 / 115034, but this entails additional CAPEX. Additionally, increasing the diameter presents the problem of increased space occupied by the facility. The problem to be solved

[0009] Therefore, there is a need for alternative processes / devices for treating aqueous fluids in which biodegradable organic matter within the fluid is converted into biogas by microorganisms. In particular, there is a need for simpler processes or systems, or smaller processes or systems, particularly those capable of reducing CAPEX and / or OPEX. The present invention focuses on these needs. means of solving the problem

[0010] The inventors have determined that an improved process can be achieved by using equipment with a smaller total volume of the bioreactor and component(s) required for the degassing and separation of solids and liquids and / or a smaller total area required for installation (installation area), such as smaller equipment (external vessel disclosed in WO 2019 / 115034), thereby maintaining the same capacity (or increasing capacity without the need for a larger installation area) while preserving the biological and physicochemical advantages of the process of WO 2019 / 115034. The inventors have determined that this method can solve the aforementioned problems, particularly in anaerobic processes. However, the inventors have considered that these aspects would also be useful for processes carried out under non-anaerobic conditions.

[0011] Therefore, the present invention

[0012] - A bioreactor (1) in which an aqueous fluid is treated by microorganisms to produce biogas from organic matter,

[0013] - A degassing unit (2) in which an aqueous suspension comprising an aqueous liquid, biogas and biomass, withdrawn from the above bioreactor, is degassed, and

[0014] - A semi-continuously operating biomass separation unit (3) in which the degassed suspension withdrawn from the above degassed unit is separated into a sludge (a) with a high biomass content and an aqueous fluid (b) with a low biomass content compared to the above degassed suspension

[0015] A process for treating an aqueous fluid containing biodegradable organic material within a facility including,

[0016] - A bioreactor batch supply step in which the above aqueous fluid to be processed is supplied into the bioreactor;

[0017] - A batch reaction step in which the aqueous fluid is treated by microorganisms and biogas is produced within the above-mentioned bioreactor;

[0018] - A semi-continuous biomass separation unit supply step in which the above-mentioned degassed aqueous suspension is withdrawn from the batch degasser and supplied into the above-mentioned biomass separation unit; and

[0019] - A degassing supply step in which an aqueous suspension containing an aqueous fluid and biomass treated by microorganisms is withdrawn from the bioreactor and supplied into the degassing unit.

[0020] It concerns a process that includes.

[0021] Between the above steps, one or more steps may be applied before the first step and / or after the last step of the above steps. For example, typically, an (additional) sludge return step may be applied after the semi-continuous biomass separation unit feed step.

[0022] Generally, the above process includes two or more cycles of the above steps. The order of the above steps is generally, first the bioreactor feed step (A), then the batch reaction step (B), then the semi-continuous biomass separation step (C), then the (additional) sludge return step (D), and then the degassing feed step (E).

[0023] In the initiation cycle (the initial cycle, for example, when the above process is first performed at a specific facility or when the process is restarted after being stopped for maintenance, etc.), the above cycle may be applied in the same order; however, if the degassing unit is empty, a simulated liquid, i.e., any liquid to be treated such as waste, effluent, or wastewater from another process, may be supplied. In the latter case, the effluent from the initial cycle may be transferred into the bioreactor (or buffer tank) to be treated in a subsequent cycle. In principle, it is also possible to operate the initiation cycle in a different way, for example, by omitting steps (C) and (D) in the initial cycle.

[0024] In addition, the present invention is a simultaneous step-performing sequential batch reaction system,

[0025] The system comprises a bioreactor having a stirrer for stirring an aqueous suspension and producing biogas within the bioreactor, a batch degassing unit having a stirrer for stirring the aqueous suspension and configured to degasify the aqueous suspension supplied from the bioreactor, and a semi-continuous biomass separation unit configured to separate the degassed aqueous suspension from the degassing unit into sludge with a high biomass content and aqueous effluent with a reduced biomass content by comparing the degassed aqueous suspension with the degassed aqueous suspension.

[0026] The above biomass separation unit

[0027] A space for storing an aqueous suspension treated from a degassing chamber, comprising a liquid-solid separation section, and further comprising an inlet for the degassing aqueous suspension connected to an outlet for discharging the aqueous suspension treated from the degassing chamber through a closeable conduit, an outlet for removing sludge, and a separate outlet for removing the discharge from the separation section through a closeable conduit.

[0028] The above bioreactor and the above degassing unit include a common or separate upper space for biogas, and the upper space includes an outlet for biogas.

[0029] The system further includes an inlet for moving an aqueous waste stream into the bioreactor as a means for moving an aqueous suspension from the bioreactor to the degassing unit.

[0030] Such a reactor system is particularly suitable for use in the process according to the present invention.

[0031] In particular, excellent results were obtained through a process for treating an aqueous fluid in which a plurality of cycles are performed according to the present invention. In the cycles,

[0032] - A bioreactor batch supply step (A) is performed (generally as the first step of a specific cycle) in which an aqueous fluid to be treated is supplied into the bioreactor, at which time the aqueous fluid already present in the bioreactor can be continued to be treated and the aqueous suspension in the degassing unit (supplied from the previous step or previous cycle) is degassing while being mixed.

[0033] - Subsequently, a batch reaction step (B) is performed in which a batch of aqueous fluid is treated by microorganisms in a bioreactor and biogas is produced, and an aqueous suspension in a degassing section is mixed and degassed.

[0034] - Subsequently, a degassed aqueous suspension is continuously drawn out from the degass section and supplied into the biomass separation section, so that an aqueous fluid (b) with reduced biomass content is filled at the outlet side, and then the aqueous fluid with reduced biomass content is continuously removed from the biomass separation section and the sludge (a) with high biomass content is continuously returned to the bioreactor, and the aqueous fluid within the bioreactor can be continuously treated by microorganisms, thereby performing a biomass separation section operation step (C).

[0035] - Subsequently, an additional sludge return step (D) is performed, at which time the supply of the degassed suspension from the degassed section to the biomass separation section is completed, the removal of the aqueous fluid with reduced biomass content from the biomass separation section is stopped, the sludge with high biomass content is continuously returned to the bioreactor, and treatment by microorganisms within the bioreactor can continue.

[0036] - Subsequently, a batch degassing tank filling step (E) is performed, at which time the required volume of aqueous fluid with reduced biomass content (the same as the volume supplied to the bioreactor in the batch supply step (A)) is withdrawn from the biomass separation unit in the previous step, and the residual sludge with high biomass content is continuously returned to the bioreactor in this step, and treatment by microorganisms within the bioreactor can continue. Brief explanation of the drawing

[0037] FIG. 1 is a schematic diagram of an example of a system according to the present invention in which the bioreactor and the degassing section are separated. FIG. 2 is a schematic diagram of a system according to the present invention as illustrated in FIG. 1, FIG. 2A shows the bioreactor batch supply step (A), FIG. 2B shows the batch reaction step (B), FIG. 2C shows the biomass separation unit operation step (C), FIG. 2D shows an additional sludge return step (D), Figure 2E illustrates the batch degassing tank filling step (E). FIG. 3 is a schematic diagram of an example of a system according to the present invention in which a bioreactor and a degassing unit are integrated within the same housing. FIGS. 4A to 4E are schematic diagrams of a system according to the present invention as illustrated in FIG. 3, each similar to FIGS. 2A to 2E. Specific details for implementing the invention

[0038] As can be seen in Example 1, the volume and installation area of ​​the entire reactor system can be significantly reduced. Additionally, the biomass separation unit, which separates the biomass from the aqueous fluid being treated, can be simplified (see external vessel (2) of WO 2019 / 115034). In particular, the same separation efficiency can be achieved by simplifying the internal structure of the separation unit (e.g., in the form of a slanted sheet) to improve separation efficiency. According to the present invention, it is not necessary to perform the feeding of the biomass separation unit, the separation of solids from the treated liquid, decanting, and the return of the concentrated sludge (high biomass content) as individual sequential steps (also including a degassing step). A major advantage of the present invention is that all these steps can be performed simultaneously (semi-continuously over the entire cycle) within the biomass separation unit. Therefore, the time applied to these steps for the same volume of fluid being treated can be increased, the required flow rate is reduced, and consequently, the size of pipes and pumps is reduced (consequently, CAPEX is also saved). Generally, the time applied to these steps is extended by at least about 2 times, preferably at least about 2 times, and especially 3 to 4 times.

[0039] Generally, the steps of the process according to the present invention are repeated multiple times. Typically, at least one subsequent cycle is performed after at least an initiation cycle, and in said subsequent cycles or cycles, a bioreactor feed step (A) and a batch reaction step (B) are performed first, followed by a biomass separation feed step (C), followed typically by an additional sludge return step (D), followed by a degassing feed step (E) as a final step. Optionally, one or more steps may be performed between said steps or after step (E), and additionally, one or more cycles may be repeated in the order of typically step (A), followed by step (B), followed by step (C), followed (optional) by step (D), followed by step (E).

[0040] Generally, except when operating the system for the first time (e.g., during initial operation or after maintenance), biogas-producing microorganisms are typically present inside the reactor. Once the microorganisms are supplied into the reactor, they generally do not need to be supplied again during subsequent cycles of the process.

[0041] The apparatus according to the present invention is preferably particularly suitable for applications in which, in a process according to the present invention, an aqueous fluid containing a biodegradable organic material is treated by microorganisms and biogas is generated from said biodegradable material.

[0042] A major advantage of the present invention is that while the conversion of organic matter by microorganisms is performed within the bioreactor, the aqueous fluid treated within the bioreactor is degassed within the degasser, and subsequently, biomass separation treatment can be carried out within the biomass separation unit.

[0043] The aqueous fluid treated in the process according to the present invention may, in principle, be any aqueous fluid containing organic matter separable, particularly under anaerobic conditions. Preferably, the aqueous fluid is selected from the group consisting of domestic wastewater, industrial wastewater (e.g., chemical industry or food processing industry), agricultural wastewater, sewage, and aqueous fluid waste from fermentation processes (e.g., residual fermentation liquid, wastewater from brewing processes, wastewater from winemaking processes). More preferably, the aqueous fluid is an aqueous slurry and an aqueous sludge. The slurry may originate from the same source as the wastewater. The water content of the waste stream treated in the process according to the present invention may vary over a wide range. Generally, the water content of the aqueous fluid to be treated is greater than 80 wt% of the total weight of the fluid, particularly at least 80 wt%, more particularly 90 wt% or more. Generally, the above water content is 99.9 wt% or less, preferably 99.5 wt% or less, more preferably 99 wt% or less, particularly 98 wt% or less, and more particularly 96 wt% or less. The total organic matter content of the aqueous fluid to be treated is generally 0.1 g COD / L or more, preferably 0.3 to 100 g COD / L, more preferably 1.0 to 50 g COD / L, particularly 5 to 50 g COD / L, and more particularly 8 to 50 g COD / L. In a specific embodiment, the total organic matter content is 1.0 to 30 g COD / L, more specifically 5 to 15 g COD / L. According to the present invention, the total organic matter content can be sufficiently reduced, generally by 50% or more, preferably by 70 to 100%, more preferably by 75 to 99%, and more preferably by 80 to 97%. The process of the present invention also provides an effluent with a low TSS (Total Suspended Solids) content in the aqueous effluent. Typically, the aqueous effluent discharged from the biomass separation unit (3) has a TSS content of less than 1.5 g / L, particularly 1.0 g / L or less, preferably about 0.6 g / L or less. Generally, the TSS of the aqueous effluent discharged from the biomass separation unit (3) is about 0.2 g / L or more, particularly about 0.3 g / L or more, more particularly about 0.4 g / L or more. Practically, the TSS content of the effluent is preferably in the range of about 0.4 g / L to about 0.6 g / L. The TSS content can be further reduced by known methods, such as filtration.

[0044] The process according to the present invention is also particularly suitable for treating waste streams having a relatively high content of fat, oil, and / or grease (FOG) and / or a relatively high content of suspended solids. TSS is the solid fraction of a fluid that can be determined by filtering (total filtration) a fluid of known weight or volume using a 1.6 μm filter, washing the residue with distilled water, drying the washed residue, and measuring the residual dry weight. Thus, TSS may contain inorganic material in addition to organic material. To distinguish organic material from inorganic material, the sample is combusted at 550°C. If all organic material is combusted, the residue of the sample is inorganic material. This combustion test is generally a practical alternative to the COD test. Generally, the TSS content of fluid waste is within the range of 0 to 20 g / L. The FOG content is generally within the range of 0 to 4 g / L. In particular, the process according to the present invention (performed under conditions where the solids in the bioreactor are at least substantially in a coagulated state) is also advantageous for treating fluid waste having a TSS content of 0.5 g / L or more, particularly 1.0 g / L or more, preferably 1.5 to 30 g / L, more preferably 2.0 to 20 g / L and / or a FOG content of 50 mg / L or more, particularly 0.1 to 4 g / L, more particularly 0.1 to 2 g / L, compared to a conventional process operated, for example, under conditions where the solids in the bioreactor are at least substantially in a granular state. One of these advantages is that the suspended solids are converted more efficiently by microorganisms. A second advantage is that the tendency of solids (including microorganisms) to float, which is typically caused by high FOG content in granular systems and can cause microorganisms to be washed away, can be reduced or completely avoided, especially when the FOG content is high.

[0045] Examples of aqueous fluids particularly suitable for treatment according to the present invention are the production or processing of dairy products (e.g., production / processing of milk, cheese, and butter), the production or processing of beverages (e.g., wine, beer, spirits, fruit juice, and milk), the production or processing of biofuels, and aqueous waste from chemical plants or agricultural facilities.

[0046] A skilled technician will know how to determine the appropriate liquid content, solid content, and microbial content within the bioreactor based on common sense, the information disclosed in this specification, and the citations mentioned in this specification.

[0047] The system (used in the process) according to the present invention comprises several parts, namely at least a bioreactor, a degassing section, and a biomass separation section. While the system is in use, said parts perform unit operations such as biogas production resulting from the conversion of organic matter by microorganisms in the bioreactor, degassing in the degassing section, and separation of concentrated sludge and purified aqueous fluid in the separation section. In chemical engineering and related fields, a unit operation refers to a basic step of a process. A unit operation involves a physical change or a chemical transformation. Accordingly, said parts may be configured as part of a device for performing unit operations, or they may be part of a device comprising several compartments (units) in which individual unit operations are performed. That is, the bioreactor and the degassing section may be different parts of a device (separated from each other), or they may be individual parts of a single (integrated) part of a device, such as an inner compartment for performing microbial treatment and an outer compartment for degassing.

[0048] In a system or process according to the present invention, the bioreactor is typically configured to operate under anaerobic conditions (airtight conditions; generally 2 to 50 mbar or more relative to atmospheric pressure).

[0049] The above bioreactor may be based on a known system for batch microbial treatment of an aqueous fluid. The bioreactor typically includes a stirrer, such as one or more stirrs, for stirring the aqueous fluid within the bioreactor. Preferably, the bioreactor is configured to treat aggregated biomass (containing microorganisms that decompose organic matter into biogas).

[0050] In the system according to the present invention, the degassing unit is also a stirring system, such as a stirring system, configured to operate under anaerobic conditions (airtight conditions; generally 2 to 50 mbar or more relative to atmospheric pressure). Generally, the upper space of the degassing unit is connected to the upper space of the bioreactor, configured so that biogas can move from one side to the other within the bioreactor. Preferably, there are multiple stirrers of different heights within the degassing unit. Preferably, the stirrers are arranged so that the fluid circulates essentially in a vertical direction. Accordingly, the stirrers are preferably arranged so that they can rotate essentially around a horizontal axis. The present invention enables the use of a degassing tank that is relatively slim and tall compared to, for example, the external vessel of WO 2019 / 115034. To save installation space, the height of the degassing unit Generally, it is about 3 m or more, preferably about 5 m or more. A relatively high degassing section is effective because sedimentation is unnecessary within the degassing section (for sedimentation, a relatively low height is advantageous, like the outer vessel of WO 2019 / 115034), and thus the horizontal diameter can be reduced and the installation area is saved. Generally, the height is about 10 m or less, particularly 6 to 8 m. The combined volume of the internal space (volume) and the upper space of the bioreactor (1) for accommodating the fluid to be treated by microorganisms is generally about 1.5 to about 10 times, preferably about 2 to about 6 times, particularly 3 to 5 times, the combined volume of the internal space (volume) for accommodating the fluid suspension to be degassing and the upper space of the degassing section.

[0051] The degassing section is a part separated from the biomass separation section. Similar to the outer vessel of WO 2019 / 115034, the degassing section may also serve as a biogas storage section, but is not necessarily so. The ceiling portion of the degassing section is generally constructed of a rigid material that does not deform, expand, or contract due to pressure changes (of biogas) within the upper space. The material of the ceiling portion may have the same or similar material properties (e.g., stiffness or mechanical strength) as the sidewalls or the sidewalls. The degassing section may be opened, for example, for maintenance, during a stage not used for biomass separation while carrying out the process according to the present invention. In this case, the gas connection between the bioreactor and the upper space of the degassing section is generally cut off. This is typically accomplished by a continuous flow through a settler during the settling / decanting stage. That is, overall, this is typically carried out in a semi-continuous manner.

[0052] A biomass separation unit, such as a biomass settling tank, is generally a system having an inclined internal structure, such as an inclined plate. The internal structure is formed to enhance the settling ability of solid particles within an aqueous fluid (e.g., suspension or sludge). The inclined internal structure may be, for example, an inclined tube or an inclined plate, and may be flat or wavy. The inclined internal structure is generally positioned at an angle of about 55 to about 60°. They are generally positioned at a distance of at least about 2 to about 10 cm from each other to ensure efficient separation and prevent clogging of the separation unit. These inclined internal structures also facilitate the separation of residual biogas from the liquid and solid phases.

[0053] The inclined internal structure (4) of the biomass separation unit (3) is preferably in the form of a thin plate and generally occupies a range of about 1 / 4 to about 2 / 3, preferably about 1 / 3 to about 1 / 2, of the working volume of the biomass separation unit (3). Generally, an outlet for the discharge (b) is provided above the upper part or the space occupied by the internal structure. A space for concentrated sludge is generally provided in the lower part of the internal structure. Generally, an upper space exists above the internal structure.

[0054] In the case of a system where the above-mentioned inclined internal structure is in the form of a thin plate and occupies between 1 / 2 and 1 / 3 of the working volume of a semi-continuous sedimentation tank (3), particularly excellent results were obtained.

[0055] The suspension treated within the biomass separation unit has excellent settling ability as it has undergone degassing in the degassing tank. Since the biomass separation unit operates semi-continuously (sludge return, filling, and decanting occur simultaneously) and the flow velocity is low, the area required for settling is much smaller, and therefore the space / area occupied by the internal structure can be relatively small. This is because solids (containing biomass) can be effectively settled, and consequently, (a) the concentrated sludge is continuously returned into the bioreactor, which reduces the total solid concentration within the biomass separation unit and enables faster solid separation due to the reduced solid concentration gradient, and (b) an aqueous fluid with reduced biomass content (effluent discharged from the separation unit) is semi-continuously formed and discharged from the system, which is generally sufficient.

[0056] In addition, considering that the total volume of the system can be significantly smaller for the same processing capacity, the reduction in volume occupied by the internal structure (e.g., thin sheet) can be more than 50%, for example, about 75%.

[0057] Next, the process and system according to the present invention will be further explained with reference to FIGS. 1 to 4.

[0058] The bioreactor (1) includes an inlet for an aqueous fluid, preferably in the upper part of the bioreactor. The inlet is generally fluidically connected to a buffer tank (5) via a conduit (c). The buffer tank mitigates fluctuations in the velocity of the fluid to be treated (typically a waste stream). Additionally, the buffer tank temporarily stores the fluid (influent) supplied into the system before a subsequent bioreactor supply cycle begins (as described below). Generally, the buffer tank (5) includes an agitator, such as a stirrer, to relatively homogenize the contents (e.g., suspended solids). Additionally, the buffer tank may include means for adding additives, such as nutrients for microorganisms or additives for pH adjustment (acid / base / buffer).

[0059] The bioreactor (1) has an outlet (d) for biogas provided in the upper space of the bioreactor. The bioreactor does not need to have an internal structure for a separation unit for degassing. The bioreactor is typically a stirred bioreactor and thus includes one or more stirrs. However, it is also possible to have other types of stirring means. The bioreactor also has an inlet for recirculating concentrated sludge discharged from the biomass separation unit, said inlet is fluidly connected to an outlet for sludge of said biomass separation unit (3) via a conduit (a). The inlet and outlet are each generally provided in the lower part of said bioreactor and biomass separation unit, respectively. The bioreactor (1), conduit (a), or biomass separation unit (3) typically has a drain pipe (WAnS in FIG. 1 and 3) for concentrated sludge. Preferably, said drain pipe is provided inside the bioreactor, typically at the bottom or near thereto. Additionally, the bioreactor (1) includes an outlet for an aqueous suspension (containing treated aqueous fluid and biomass), which is fluidically connected to the inlet of the degassing unit (2) via a conduit (e). In one embodiment, the outlet for the aqueous suspension of the bioreactor is located at the bottom of the reactor. This enables at least substantially complete discharge from the bioreactor within the degassing unit. Such an embodiment is illustrated in FIGS. 1 and 2. FIGS. 1 and 2 also show an embodiment in which the bioreactor (1) and the degassing unit (2) are separated.

[0060] In other embodiments (e.g., see FIG. 3 and 4), the outlet is located in the middle or upper part of the bioreactor, higher than the inlet for the aqueous suspension into the degasser. This makes it possible to draw the suspension from the bioreactor (1) and supply it into the degasser (2) using at least partially gravity flow. The degasser is typically a stirred degasser. The degasser does not require an internal structure of the separation unit. An outlet (f) for biogas is provided within the upper space of the degasser (2). An outlet for the degassed aqueous suspension provided within the degasser (2), which has an inlet for the degassed aqueous suspension into the biomass separation unit (3), is connected by a conduit (g). An outlet from the degasser (2) is typically provided at or near the bottom of the degasser, allowing the degassed suspension to be essentially completely removed. The location of the inlet into the biomass separation unit varies depending on the type of separation unit. In particular, a biomass separation unit is preferred having an internal separation unit structure (4) in the middle or upper part of the biomass separation unit, wherein an inlet for the degassed suspension is provided at or below the lowest part of the internal separation unit structure and an outlet (b) for the discharge is located at a higher place, at the highest part of the internal separation unit structure, near or above it, so that during at least part of the separation stage, an upward liquid flow is formed through the internal structure and solids, such as biomass, move downward, thereby reducing the solid content at the outlet (b) for the discharge. This design enables semi-continuous use of the biomass separation unit while the supply of the aqueous suspension and the withdrawal of the discharge (b) and optionally the withdrawal of sludge (a) from the biomass separation unit are taking place. Optionally, a biogas outlet (h) is provided within the upper space of the biomass separation unit, typically within or near the ceiling part (above the discharge outlet (b)).

[0061] As shown in FIGS. 3 and 4, the bioreactor (1) and the deaeration unit (2) can be integrated within a single housing. Thus, they can constitute part of a single tank / vessel. However, the bioreactor and the deaeration unit remain separate compartments, so unintended mixing of contents does not occur. Thus, the aqueous suspension in the bioreactor and the aqueous suspension in the deaeration unit are separated by a partition (i) through which the aqueous fluid cannot pass. However, the upper space can be shared. This design allows for a further reduction in the installation area of ​​the system. In a horizontal view, the bioreactor typically forms the interior within a single housing, and the deaeration unit forms the exterior (essentially surrounding the bioreactor). This is because the internal structural volume of the deaeration unit must be smaller than that of the bioreactor. Since the internal volume is larger, strength requirements for the materials used in the system are relaxed. If the bioreactor is located externally, the force applied to the partition becomes much greater when the bioreactor is full and the degassing section is empty, leading to a risk of collapse if the partition is not sufficiently strong.

[0062] Particularly preferably, the system is an integrated, at least substantially cylindrical container, wherein the bioreactor (1) forms at least substantially cylindrical container and the bioreactor is at least substantially surrounded by the degassing section (2).

[0063] The process according to the present invention comprises at least four steps as described above. Where a conduit is described as closed below, this may mean that a valve is closed to block flow, but it may also mean that a pump is not operating. That is, it means that no flow occurs within the conduit.

[0064] In the bioreactor batch supply stage (A), the aqueous fluid to be treated is supplied into the bioreactor. The aqueous fluid is supplied into the bioreactor (1) through a conduit (c) fluidically connected to the outlet of the buffer tank (5). The fluid can be supplied to any point within the reactor. At this stage, the conduit (e) between the bioreactor (1) and the degassing unit (2) is generally closed to prevent the newly supplied fluid to be treated from moving to the degassing unit, but in principle, it may be open. It should be noted that microorganisms may convert biodegradable material during the supply (batch supply). After the first cycle, the contents of the degassing unit also undergo degassing at this stage. Therefore, the conduit (g) between the degassing unit and the biomass separation unit (3) is also typically closed. Generally, the recirculation of the sludge (a) from the previous cycle is already completed. Therefore, the conduit (a) may also be closed. Generally, the removal of the previous cycle's effluent (b) is also already completed, and therefore the conduit (b) may also be closed.

[0065] After the batch supply stage (A) of the bioreactor, the batch reaction stage (B) proceeds. In this stage, typically, no supply into the bioreactor or withdrawal of the treated suspension takes place. That is, the conduits (c, e) are closed. Degassing within the degassing unit (2) is allowed to continue (after the initial (initial) cycle). Therefore, although conduit (g) is also generally still closed, if sufficient degassing has taken place before microbial treatment takes place in the bioreactor (1), withdrawal of the degassing suspension from the degassing unit (2) into the biomass separation unit (3) can, in principle, begin. The separation unit is generally not in operation at this stage. The volume of the aqueous suspension in the bioreactor (1), where microbial treatment of the aqueous fluid takes place in a batch (cycle) manner, is generally equal to or greater than the volume of the aqueous suspension degassed in a batch (cycle) manner in the degassing unit (2). Generally, the volume of the aqueous suspension in the bioreactor (1) is less than 10 times the volume of the aqueous suspension in the degassing section (2), preferably about 1.5 to about 4 times the volume of the aqueous suspension in the degassing section, and more preferably about 2 to about 3 times the volume of the aqueous suspension in the degassing section. If the volume of the aqueous suspension in the bioreactor is large, there is an advantage that the installation area can be reduced.

[0066] In the semi-continuous biomass separation unit feeding step (C) that follows step (B), microbial treatment within the bioreactor (1) generally continues at least after the initiation cycle (however, the biogas production rate is reduced at this stage). At this stage, the contents degassed from the degasser are pumped into the biomass separation unit through conduit (g). Thus, the degasser is generally at least substantially empty. Typically, 90 to 100 percent of the degassed suspension is fed into the biomass separation unit (3). Once the separation unit is filled, separation into concentrated sludge (a) and an aqueous fluid with reduced solid content is performed, and while the feeding into the separation unit continues, both the concentrated sludge (a) and the aqueous fluid (b) can be withdrawn from the separation unit. At the start of this stage, the biomass separation unit is generally essentially empty. At least, the fluid level is lower than the outlet for the purified aqueous liquid (b). The outlet for the purified aqueous liquid is generally positioned higher than the outlet for the concentrated sludge (the outlet for the sludge is typically located at or near the bottom), typically higher than the inlet for the degassed aqueous suspension, and typically equal to or higher than the upper part of the internal structure of the separation unit. Thus, in this stage, continuous feeding into the separation unit is generally performed so that the separation unit is filled until the height of the fluid reaches the height of the outlet for the purified aqueous liquid, and then the sludge (a) and fluid (b, effluent) are withdrawn from the separation unit. Thus, in this stage, the feeding, separation, and withdrawal of the sludge (a) and purified aqueous liquid (b) are performed semi-continuously (i.e., in the initial stage, only feeding proceeds without withdrawal of the purified liquid, and then feeding and withdrawal are performed continuously). However, in principle, it is also possible to perform the feeding of the suspension to be separated and the withdrawal of the sludge (a) and purified aqueous fluid (b) intermittently.Generally, the withdrawal of the purified liquid (b) can be carried out simply by gravity flow without the need for a pump. Generally, the use of a pump is required to recirculate the concentrated sludge (a) to the bioreactor.

[0067] It is desirable that solid particles other than biomass that may exist in the aqueous fluid, such as mineral particles, are also included in the finally concentrated sludge. Therefore, the purified aqueous fluid not only has a reduced biomass content but also a reduced total solid content.

[0068] Preferably, the concentrated sludge (a) with a high biomass content is recirculated to the bioreactor, and the purified aqueous fluid (b) with reduced biomass content is removed from the biomass separation unit and discarded as effluent or undergoes further downstream processes. The sludge (a) is returned to the bioreactor (1) through conduit (a). The recirculation of the sludge (a) and the removal of the purified aqueous fluid (b) typically take place during the biomass separation unit feeding step (C), but may also be performed thereafter, before step (E) or (A) begins. By rule of thumb, the purified aqueous fluid (b) accounts for 20–45 vol%, particularly 25–40 vol%, and more particularly 30–35 vol% of the degassed suspension separated within the biomass separation unit, and the concentrated sludge (a) accounts for the remainder. Therefore, in the recirculation process, the sludge (a) with a high biomass content accounts for 55–80 vol%, particularly 60–75 vol%, and more particularly 65–70 vol% of the total amount of sludge (a) plus the aqueous fluid (b) with reduced biomass content.

[0069] If biomass is overproduced, some of the sludge may be discarded. Therefore, the aqueous fluid (b, effluent) withdrawn from the system may be discarded or further downstream treated (not shown). Suitable downstream treatment processes are generally known in the art.

[0070] Generally, essentially all degassed contents of the degasser are transferred to the biomass separation unit. A small amount of liquid may remain at the bottom, for example, to a height of about 10 to 25 cm. If the degasser needs to be completely emptied, it is generally necessary to use the lining of the bottom portion of the degasser. Once all the degassed suspension to be supplied into the separation unit (2) has been transferred, conduit (g) can be closed. Preferably, the withdrawal of contents from the biomass separation unit continues until the separation unit is at least substantially empty. At this stage (step 'D' in FIG. 2D and 4E), typically sludge (b) is recirculated to the biomass separation unit through conduit (a). The withdrawal of effluent is typically stopped when the supply to the biomass separation unit is stopped or immediately after this stage begins. In principle, at this stage, it is possible to begin filling the contents of the bioreactor (2) into the degasser (2) through conduit (e).

[0071] However, generally, as illustrated in FIG. 2E and FIG. 4E, the filling of the degassing section is started in a separate step (E) or continues at least during this step.

[0072] Step (E) is a degassing section feeding step, in which an aqueous suspension containing an aqueous fluid and biomass treated by microorganisms is drawn from the bioreactor and fed into the degassing section. Thus, conduit (e) can be opened while other conduits remain closed.

[0073] When the contents of the bioreactor (1) are supplied to the degassing unit (2) and sufficiently emptied, the next cycle can begin. The aqueous fluid to be treated is supplied back into the bioreactor, and then steps (B), (C), (D), and (E) proceed.

[0074] The process according to the present invention is particularly advantageous for anaerobic treatment in which biogas is generated from biodegradable organic matter. Generally, both the interior of the bioreactor and the interior of the degassing unit are maintained under anaerobic conditions. The biomass separation unit may be operated under anaerobic conditions, but anaerobic conditions must not be maintained. For example, the biomass separation unit may be periodically opened for maintenance or cleaning while the bioreactor and / or degassing unit are in use, for example, during the bioreactor feeding stage (A), the batch reaction stage (B), and / or the degassing unit feeding stage (E). The pressure in the upper space may be atmospheric pressure (0 barg). However, preferably, the upper space of the bioreactor and degassing unit is maintained under anaerobic conditions under a pressure exceeding atmospheric pressure (lower pressure), for example, up to 100 mbarg, particularly 5 to 70 mbarg, and ideally 0 to 70 mbarg.

[0075] The design of the facility (used in the process) according to the present invention is also advantageous in that the upper space of the bioreactor (1) (i.e., the upper part of the fluid containing biogas in the reactor) is connected to the upper space of the degassing section through a channel. This provides a hermetic system, thereby substantially eliminating the concern for odors caused by the discharge of biogas, which frequently occurs, particularly in anaerobic contact reactors. Additionally, optionally, the biogas is connected to the separation section (3).

[0076] The process according to the present invention enables convenient real-time system monitoring and optimization and automation based on sequential biogas production profiles (biogas production rate over time). System capacity can be monitored in real time through the biogas production volume in each profile.

[0077] In the process or facility according to the present invention, the system load and the duration of the reaction / sedimentation stage can be adjusted and optimized based on a "standard" biogas profile, i.e., a reference / standard biogas profile defined by the operator for the process. The biogas profile contributes to effective control by linking the supply and sequence to biogas production and prevents system overload. In the case of known continuous processes, a biogas profile suitable for this purpose cannot be obtained. The use of such a biogas profile is a major advantage compared to processes performed continuously, such as anaerobic membrane reactors (AnMBR), continuous stirred tank reactors equipped with dissolved biogas flotation (DBF), or treatment in contact processes disclosed by Naehle (Wat. Sci Tech. Vol 24, No 8, 00 179-191 (1991)) in the early 1990s. For example, the continuous process disclosed by Naehle is particularly vulnerable to TSS and / or FOG overloads in the bioreactor or effluent. This is because continuous operation systems, such as those disclosed by Naehle, cannot target and decompose TSS and FOG. Therefore, in continuous processes, new substrates (biodegradable materials) must be continuously fed to the biomass. Waste streams are generally relatively heterogeneous streams containing various degradable components with different chemical compositions and / or physical states (dissolved / suspended). This generally means that relatively easily degradable feed components (e.g., degradable soluble / dissolved components) and difficult-to-degrade feed components (e.g., suspended solids, FOG) are continuously fed into a bioreactor containing biomass, thereby providing a continuous supply of substrates (biomass) that are relatively easy to degrade by microorganisms. Therefore, in continuous processes, easily degradable substrates are generally abundant. Microorganisms generally prefer easily degradable components.Therefore, in a continuous process, components that are relatively difficult to decompose (e.g., suspended solids, FOG) accumulate, causing the biomass to float and resulting in the loss of undesirable or unacceptable biomass and / or unseparated organic matter as effluent. The present invention creates an abundance / poverty situation by batch operation within the bioreactor so that the biomass is separated into fats and solids before a new supply of biomass is introduced. In the present invention, this is combined with appropriate degassing of the biomass for sedimentation. Accordingly, the inventors have discovered an effective method for carrying out the process according to the present invention, which includes the effective operation of the batch stage, particularly in treating aqueous fluids such as wastewater with relatively high TSS and / or FOG content as described herein. This achieves significant biological performance compared to an essentially entirely continuous process. This can be achieved particularly by one or more of the following measures.

[0078] * Simultaneous reaction / precipitation stage – This allows for a significant increase in precipitation time without reducing the duration of the reaction stage (generally at least twice as much as conventional AnSBR). This is impossible with conventional AnSBR.

[0079] * Simultaneous Supply / Withdrawal Steps – This system also enables simultaneous supply and withdrawal (decanting) steps and reduces the number of steps per cycle. This is impossible with conventional AnSBRs.

[0080] * Reduction in required volume / area of ​​inclined internal structure (thin sheet) - Generally, the required volume / area of ​​the thin sheet is reduced by up to about 2 / 3 while maintaining essentially the same separation efficiency.

[0081] * No pressurized internal structure required within the degassing tank – this enables simplification, increased safety, easier construction, and easier management of the sloped internal structure (e.g., thin plate) in the event of a blockage in the biomass separation section.

[0082] * Optimization of biomass separation - Since biomass is separated semi-continuously in a separate separation unit (batch degassing), decanting and sludge return times can be significantly increased, thereby allowing for a reduction in pipe diameter and pump requirements.

[0083] * Reduction of installation area - Although the batch degassing tank requires at least twice the batch size, there is no limit on the height. Therefore, the tank is slim and tall (preferably about 6 to 8 m) and occupies a small installation area. In addition, according to the present invention, the batch degassing tank can be integrated within the reactor tank, allowing the structure to be miniaturized, thereby enabling optimization and reduction of the installation area.

[0084] Degassing time can be increased without affecting cycle length.

[0085] As used in this specification, the term "or" is defined as "and / or" unless specifically stated otherwise.

[0086] As used in this specification, the terms “one” or “one” are defined as “at least one” unless specifically stated otherwise.

[0087] Nouns expressed in the singular form (e.g., compounds, additives, etc.) also include the plural form.

[0088] As used herein, the term “(at least) substantially” means having the generally mentioned general feature or function. When referring to a quantifiable feature, this term is used to mean, in particular, at least 50% of the maximum value of the feature, more particularly exceeding 75%, and more particularly exceeding 90%. As used herein, the term “essentially absent” means that a substance is generally absent (below the detection limit achievable by analytical techniques available as of the effective filing date) or that said substance is present in such a small amount that it does not significantly affect the characteristics of the product in which it is essentially absent. In practice, when used in a quantitative sense, a substance is generally considered to be substantially absent when its content is 0 to 1 wt%, particularly 0 to 0.5 wt%, and more particularly 0 to 0.1 wt%.

[0089] In this application, the term "about" generally means a deviation from a given value of 15% or less, particularly a deviation of 10% or less, more particularly a deviation of 5% or less.

[0090] In this specification, “biodegradable organic material” is an organic material that can be converted, in particular into biomass or methane, by microorganisms in a reactor, typically under conditions that are essentially anaerobic.

[0091] As used herein, the term "fluid" refers to a mixture of liquids having at least one different phase, such as liquids and suspensions, which can flow without the application of external pressure (pressure other than gravity).

[0092] In this specification, “organic material” is any organic material that can be chemically oxidized and is measurable by the chemical oxygen demand (COD) test method specified in ISO 6060:1989. The content of organic material is generally expressed in g COD, a unit representing the number of grams of oxygen consumed to oxidize the organic material.

[0093] A skilled technician is familiar with terms such as 'top', 'bottom', 'middle', 'bottom', 'near bottom', 'top', and 'near top'. Generally, these terms are understood through their interrelationships, and a skilled technician will be able to practice the invention based on common sense, the information and references disclosed herein, and the details of each part of the facility (e.g., bioreactors, separate vessels, volumes of material contained in bioreactors or compartments).

[0094] According to the rule of thumb, the 'nearby' of a specific reference point (e.g., 'floor' or 'top') generally refers to a 'relative height of up to ±20% from that reference point,' specifically a 'relative height of up to ±10% from that reference point,' rather than a 'relative height of up to ±15% from that reference point.' Relative height is the value obtained by dividing the distance from the floor by the total height (the height difference between the floor and the top).

[0095] By rule of thumb, the 'upper' part generally means the upper 1 / 2, specifically the upper 1 / 3 part, and the 'lower' part generally means the lower 1 / 2, specifically the lower 1 / 3 part. When referring to the middle part, it specifically means the middle 1 / 3 part (from the bottom 1 / 3 to the top 1 / 3).

[0096] For the sake of clarity and concise description, the features of the present invention will be described below through identical or different embodiments. However, it should be understood that embodiments including all or part of the described features may also be included within the scope of the present invention. Terms used herein but not specifically defined refer to WO 2013 / 139823 or WO 　 Defined in 2019 / 115034, or otherwise based on common sense.

[0097] The present invention will be explained below through the following examples.

[0098] Example 1: Case Study, Comparison with WO 2019 / 115034

[0099] A case study was conducted as an example to compare the advantages of the process according to the present invention with WO 2019 / 115034 in a quantifiable manner.

[0100] A case study was conducted based on the following supply flow and composition.

[0101]

[0102] Legend:

[0103] COD = Chemical Oxygen Demand

[0104] VFA-COD = COD formed by volatile fatty acids

[0105] TSS = Total Suspended Solids

[0106] VSS = Volatile Suspended Solids

[0107] The parameter requirements and savings effects were calculated as follows.

[0108]

[0109] Example 2: Industrial-scale verification, comparison with WO 2019 / 115034

[0110] First, the wastewater streams from the wine and spirits distillery were treated for about 60 days in accordance with WO 2019 / 115034. Then, the process according to the present invention was applied to treat them.

[0111] The supply and system conditions were as follows.

[0112]

[0113] As a result of applying the process of the present invention, TCOD, SCOD (available COD), and VLR (volume loading rate, unit: kg COD / m³) 3It was confirmed that essentially identical performance was maintained in terms of day), SRT (solid retention time, unit: day), and MLSS (mixed liquid suspended solids, unit: g / L). As shown in the table below, performance was maintained. When applying the process according to the present invention, both the degassing tank and the semi-continuous sedimentation tank were operated at the operable parameters, cycle times, and flow rates required for the full scale.

[0114]

[0115] Therefore, it can be seen that the process according to the present invention is an excellent alternative to the process according to WO 2019 / 115034.

[0116] The sedimentation rate requirement for the biomass separation unit was met.

[0117] In addition, the process cycle could be reduced.

[0118] High performance was confirmed with a VLR of at least 5 g COD / L day.

[0119] Excellent SCOD and TCOD removal efficiency was confirmed.

Claims

Claim 1 - A bioreactor (1) in which an aqueous fluid is treated by microorganisms under anaerobic conditions to produce biogas from biodegradable organic matter; - a degassing unit (2) in which an aqueous suspension containing an aqueous liquid, biogas, and biomass, drawn from the bioreactor, is batch degassingly performed; and - a semi-continuously operating biomass separation unit (3) in which the degassing suspension drawn from the degassing unit is separated into (a) sludge with a high biomass content and (b) an aqueous fluid with a reduced biomass content compared with the degassing suspension supplied into the biomass separation unit (3), the process for treating an aqueous fluid containing biodegradable organic matter within the facility comprising: - (A) a bioreactor batch supply step in which the aqueous fluid to be treated is supplied into the bioreactor; - (B) a batch reaction step in which, within the bioreactor, the aqueous fluid is treated by microorganisms under anaerobic conditions and biogas is produced; - (C) the A process comprising: (E) a semi-continuous biomass separation unit supply step in which a degassed aqueous suspension is withdrawn from the degassed unit and supplied into the biomass separation unit, the semi-continuous supply step including an initial step in which an aqueous fluid with reduced biomass content is not withdrawn and a continuous step in which supply and withdrawal proceed simultaneously; and (E) a degassed unit supply step in which an aqueous suspension containing an aqueous fluid and biomass treated by microorganisms is withdrawn from the bioreactor and supplied into the degassed unit. Claim 2 In claim 1, the process comprises a plurality of cycles in which one or more subsequent cycles are performed after the initiation cycle, wherein in the subsequent cycles or cycles, the aqueous fluid to be treated is supplied into the bioreactor, and the treatment of the aqueous fluid already present in the bioreactor may continue, and a bioreactor batch supply step (A) is performed in which the aqueous suspension in the degassing unit (supplied in the previous step or previous cycle) is degassing during the mixing process; - Subsequently, a batch reaction step (B) is performed in which the batch of aqueous fluid within the bioreactor (1) is treated by microorganisms and biogas is produced, and the aqueous suspension within the degassing unit (2) is degassing; - Subsequently, the degassing aqueous suspension is continuously drawn out from the degassing unit (2) and supplied into the biomass separation unit (3) until the biomass separation unit is filled to a height where the outlet for the aqueous fluid (b) with reduced biomass content is located, and subsequently, during this step, the aqueous fluid with reduced biomass content is continuously removed from the biomass separation unit and the sludge (a) with high biomass content is continuously returned to the bioreactor, and at this time, a biomass separation unit operation step (C) is performed in which the aqueous fluid within the bioreactor can be continuously treated by microorganisms; - Subsequently, an additional sludge return step (D) is performed, at which time the biomass from the degassing unit of the degassing suspension Supply to the separation unit is completed, removal of the aqueous fluid with reduced biomass content from the biomass separation unit is stopped, and the sludge with high biomass content is continuously returned to the bioreactor, and treatment by microorganisms within the bioreactor may continue;Subsequently, a batch degassing tank filling step (E) is performed, wherein the required volume of aqueous fluid with reduced biomass content (identical to the volume supplied to the bioreactor in the batch supply step (A)) is withdrawn from the biomass separation unit in the previous step, and residual sludge with high biomass content is continuously returned to the bioreactor in this step, and the process in which treatment by microorganisms within the bioreactor can continue; Claim 3 In claim 2, the process of withdrawing the aqueous fluid with reduced biomass content from the biomass separation unit by gravity flow. Claim 4 A process according to any one of claims 1 to 3 in which a concentrated sludge (a) with a high biomass content is recirculated to the bioreactor and a purified aqueous fluid (b) with reduced biomass content is removed from the biomass separation unit and discarded as effluent or undergoes an additional sub-process. Claim 5 A process according to claim 2 or 3 in which the recirculation of the sludge (a) and the removal of the purified aqueous fluid (b) are performed during or after the biomass separation unit operation step (C), but before the start of step (E) or (A). Claim 6 A process according to any one of claims 1 to 3, wherein the biomass separation unit has an inclined internal structure to improve the settling properties of the biomass. Claim 7 In claim 6, the process in which the inclined internal structure occupies 1 / 2 to 1 / 3 of the working volume of the biomass separation unit. Claim 8 A process according to any one of claims 1 to 3, wherein the volume per batch of aqueous fluid treated by microorganisms in the bioreactor is about 2 to about 3 times the volume of aqueous suspension degassed in the degasser. Claim 9 A process according to any one of claims 1 to 3, wherein microbial treatment within the bioreactor is carried out under anaerobic conditions, and the bioreactor and the degassing unit are maintained under anaerobic conditions. Claim 10 A process according to any one of claims 1 to 3, wherein the aqueous fluid is a fluid waste having a total chemical oxygen demand in the range of 1.0 to 50 g / L. Claim 11 In claim 10, a process in which the total chemical oxygen demand is within the range of 5 to 50 g / L. Claim 12 A process according to any one of claims 1 to 3, wherein the aqueous fluid is a fluid waste having a total suspended solids content of 0.5 g / L or more. Claim 13 In claim 12, the process in which the aqueous fluid is a fluid waste having a total suspended solids content of 1.0 to 30 g / L. Claim 14 A process according to any one of claims 1 to 3, wherein the aqueous fluid is a fluid waste having a total suspended solids content of 0 to 20 g / L. Claim 15 A process according to any one of claims 1 to 3, wherein the aqueous fluid is a fluid waste having a total fat, oil and / or grease (FOG) content in the range of 0 to 4 g / L. Claim 16 A process according to any one of claims 1 to 3, wherein the aqueous fluid is a fluid waste having a total fat, oil and / or grease (FOG) content of 50 mg / L or more. Claim 17 In claim 16, the process in which the fluid waste is a fluid waste having a FOG content in the range of 0.1 to 2 g / L. Claim 18 A simultaneous step sequential batch reaction system comprising a bioreactor having a stirrer for stirring an aqueous suspension within the bioreactor and producing biogas, further comprising a degassing unit having a stirrer for stirring the aqueous suspension and configured to degassing the aqueous suspension supplied from the bioreactor, and further comprising a semi-continuous biomass separation unit configured to separate the degassing aqueous suspension from the degassing unit into sludge with a high biomass content and aqueous effluent with a reduced biomass content by comparing the degassing aqueous suspension with the degassing aqueous suspension, wherein the biomass separation unit includes a liquid-solid separation unit as a space for storing the aqueous suspension treated from the degassing chamber, and further comprises an inlet for the degassing aqueous suspension connected to an outlet for discharging the aqueous suspension treated from the degassing chamber through a closeable conduit, an outlet for removing sludge, and a separate outlet for removing the effluent from the separation unit through a closeable conduit, wherein the bioreactor and the degassing unit include a common or separate upper space for biogas, and A system in which the upper space includes an outlet for biogas, and further includes an inlet for moving an aqueous waste stream into the bioreactor as a means for the system to move an aqueous suspension from the bioreactor to the degassing section. Claim 19 In claim 18, the system having a slanted internal structure for improving the settling properties of biomass in an aqueous fluid, wherein the liquid-solid separation unit is a system. Claim 20 A system according to claim 18 or 19, wherein the volume of the internal structure of the bioreactor (i.e., the volume of the space containing the suspension and the upper space) is 2 to 10 times the volume of the internal structure of the degassing section (i.e., the volume of the space containing the suspension and the upper space). Claim 21 A system according to claim 20, wherein the volume of the internal structure of the bioreactor (i.e., the volume of the space containing the suspension and the upper space) is 3 to 6 times the volume of the internal structure of the degassing section. Claim 22 A system according to claim 18 or 19, wherein the bioreactor and the degassing unit are separate compartments of a single vessel, and the bioreactor is located in the central part of the single vessel and is surrounded by the degassing unit. Claim 23 In claim 22, the system wherein the bioreactor and the degassing unit are part of a single vessel and share the same upper space. Claim 24 A system according to claim 22, wherein the bioreactor and the degassing section are separated by an intermediate wall, and a channel configured to allow an aqueous suspension to pass from the bioreactor to the degassing section by gravity flow.

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