Batch partial nitritation reactor with improved granule selection efficiency and apparatus for removing nitrogen in sewage and wastewater including same

Abstract

Disclosed is a nitrogen removal apparatus for removing nitrogen in sewage / wastewater, wherein a partial nitritation reaction and an anaerobic ammonium oxidation reaction are linked and granule selection efficiency in a partial nitritation reactor is improved. According to one aspect of the present invention, provided is an apparatus for removing nitrogen in sewage / wastewater, comprising a batch partial nitritation reactor that receives sewage / wastewater and performs a partial nitritation reaction to adjust ammonia nitrogen and nitrite nitrogen in the sewage / wastewater at a preset ratio, wherein the batch partial nitritation reactor is operated in a sewage / wastewater inflow / discharge step and a reaction step.

Description

Batch-type partial nitrification reactor with improved granule screening efficiency and nitrogen removal device in wastewater including the same

[0001] The present invention relates to a nitrogen removal device for wastewater comprising a partial nitrification process, and more specifically, to a nitrogen removal device comprising a sequencing batch reactor capable of effectively separating granules and flocs in a partial nitrification process using ammonium oxidation bacteria granules.

[0002] The content described in this section merely provides background information regarding the present embodiment and does not constitute prior art.

[0003] Standard activated sludge processes and their variations are commonly used for wastewater treatment. In these processes, microbial activity and settling ability significantly affect treatment efficiency; however, conventional activated sludge processes face limitations in increasing microbial concentrations, poor settling ability, and unstable treatment efficiency depending on operating conditions. To address these issues, technologies such as media-based biofilm processes and membrane bioreactors have been developed; however, these technologies have disadvantages, including high installation costs and fouling of the media or membranes.

[0004] Recently, technologies utilizing sludge granules are also being applied to overcome these problems. For example, Aerobic Granular Sludge (AGS), which is proposed as a technology to replace the existing activated sludge process, consists of a dense and self-fixed microbial aggregate and offers advantages such as rapid settling speed, high biomass retention, biological nitrogen and phosphorus removal, and high treatment efficiency with a short retention time.

[0005] The most important process for efficiently maintaining such sludge granules is to introduce a short settling stage to separate and discharge flocs with low settling ability and selectively maintain granules with high settling ability within the reactor. Accordingly, a Sequencing Batch Reactor (SBR) is generally known to be suitable for the process of growing and maintaining sludge granules.

[0006] Figure 1 is a conceptual diagram illustrating the operation method of a typical batch reactor (SBR) applied to biological wastewater treatment using aerobic granular sludge (AGS).

[0007] Referring to FIG. 1, a batch reactor (10) using an AGS includes an outlet (20) and an inlet (30), and may further include a separate air supply means (not shown) or a mechanical stirring means (not shown) inside the reactor. The batch reactor (10) can be operated continuously by repeatedly performing a single unit cycle consisting of inflow, reaction, sedimentation, and discharge processes.

[0008] During the reaction process, oxygen is supplied into the reaction vessel (10) or stirring is performed to allow the microbial reaction by the granules to take place.

[0009] After the reaction is completed, a sedimentation process is carried out in the reaction tank (10). As described above, the batch reaction tank (10) using granules maintains a short sedimentation time so that granules with good sedimentation properties are located at the bottom of the reaction tank (10), and sludge and / or floc with poor sedimentation properties are included in the supernatant so that the granules and supernatant are separated.

[0010] After sedimentation is complete, the batch reactor (10) discharges the supernatant liquid to the outside through the outlet (20). At this time, so that the settled granules are not discharged together and remain within the reactor (10), the discharge volume of the supernatant liquid is generally controlled to a level of 20 to 50% of the effective wastewater volume within the reactor, and for this purpose, the outlet (20) of the reactor (10) is positioned at a preset height from the bottom of the reactor (10). In the prior art, the preset height at which the outlet (20) is formed is set to half the height of the entire reactor (10).

[0011] When sedimentation is complete, new wastewater flows into the reaction tank (10). As such, some of the treated water from the reaction tank (10) is discharged and wastewater flows in again, the ratio of wastewater exchange based on the total volume of the reaction tank (10) can be defined as the Exchange Ratio (ER). In a typical batch reaction tank (10), the Exchange Ratio (ER) is operated to be maintained in the range of 30 to 50%.

[0012] This conventional batch reactor (10) has a problem in that it can only discharge some flocs with poor settling ability due to the short settling time, and therefore flocs with poor settling ability still remain in the reactor (10).

[0013] Meanwhile, in addition to the activated sludge process, in nitrogen removal processes that treat high concentrations of nitrogen, such as partial nitrification and anaerobic ammonium oxidation, batch reactors (SBRs) are applied as a partial nitrification process to effectively inhibit the activity of nitrite-oxidizing bacteria (NOBs). Furthermore, a process utilizing AOB granules is being applied to maintain a high concentration of ammonium-oxidizing bacteria (AOBs) within the reactor and to achieve rapid nitrogen removal without the supply of an external carbon source.

[0014] However, in conventional batch partial nitrification processes, even when 50% of the treated water is discharged and new wastewater is introduced, the ammonia concentration in the incoming wastewater is diluted due to the settled sludge and treated water remaining in the reaction tank. As a result, there are limitations in inhibiting the activity of NOB by utilizing free ammonia, and since nitrite nitrogen, which serves as food for NOB, always remains at the time the reaction starts, there is a problem that conditions favorable for the growth of NOB may be formed.

[0015] Accordingly, in batch reactors utilizing granules, various attempts are being made to improve the treatment efficiency of subsequent reaction stages by increasing the exchange rate of untreated wastewater within the reactor and effectively separating granules from flocs with poor settling properties.

[0016] One embodiment of the present invention aims to provide a nitrogen removal device that can efficiently separate granules and flocs in a batch partial nitrification reactor to secure a high concentration of granules within the reactor, thereby stably performing partial nitrification and subsequent anaerobic ammonium oxidation to effectively remove nitrogen from wastewater, while simultaneously shortening process operation time and increasing throughput.

[0017] In addition, one embodiment of the present invention has the objective of providing a method for controlling a batch reactor that can selectively select and maintain granules of a desired size within the reactor by controlling the inflow rate and the amount of inflow water.

[0018] According to one aspect of the present invention, a device for removing nitrogen from wastewater is provided, comprising: a batch partial nitrification reactor that receives wastewater and performs a partial nitrification reaction to adjust ammoniacal nitrogen and nitrite nitrogen in the wastewater to a preset ratio; a treated water storage tank that receives floc and treated water discharged from the batch partial nitrification reactor and performs solid-liquid separation to separate them into supernatant and solids; and an anaerobic ammonium oxidation reactor that receives the supernatant from the treated water storage tank and removes ammoniacal nitrogen and nitrite nitrogen in the wastewater as nitrogen gas, wherein the batch partial nitrification reactor is operated in a wastewater inflow / outflow stage and a reaction stage.

[0019] According to one aspect of the present invention, the batch partial nitrification reactor is characterized by containing AOB granules inside and being operated so that only nitrification is performed.

[0020] According to one aspect of the present invention, the wastewater inflow / outflow step of the batch partial nitrification reactor is characterized by the simultaneous inflow of untreated wastewater and the outflow of treated water after the reaction is completed in the batch partial nitrification reactor.

[0021] According to one aspect of the present invention, the batch partial nitrification reactor is provided with a wastewater inlet at the bottom of the reactor and a treated water outlet at the top of the reactor, and the wastewater inlet supplies wastewater to move in a plug flow or an upward flow in a laminar state so that the untreated wastewater moves uniformly along the cross-section of the reactor.

[0022] According to one aspect of the present invention, during the inflow / outflow stage of wastewater in the batch partial nitrification reactor, the untreated wastewater flowing in is characterized by moving in an upward flow while maintaining the Reynolds number (Re) at 3000 or less so that the interface with the treated water that has already been treated in the reactor is not excessively mixed.

[0023] According to one aspect of the present invention, the amount of treated water replaced in the reactor by untreated wastewater introduced during the inflow / outflow stage of the batch partial nitrification reactor is characterized by being 80% to 120% of the effective volume of the reactor.

[0024] According to one aspect of the present invention, the batch partial nitrification reactor is characterized by controlling the amount of discharged treated water to adjust the ratio of nitrite nitrogen to ammonia nitrogen to a preset range and supplying it to the anaerobic ammonium oxidation reactor.

[0025] According to one aspect of the present invention, the batch partial nitrification reactor is characterized by controlling the nitrogen concentration in the wastewater flowing into the anaerobic ammonium oxidation reactor by adjusting the amount of water discharged to the treated water adjustment tank in the inflow / outflow stage to be greater than the effective volume of the reactor when the ratio of nitrite nitrogen to ammonia nitrogen in the treated water exceeds a preset range.

[0026] According to one aspect of the present invention, the batch partial nitrification reactor is characterized by being able to select the size of the granules retained in the reactor by changing the upward flow rate of the influent water in the reactor by adjusting the supply time of the wastewater supplied to the reactor in the inflow / outflow stage.

[0027] According to one aspect of the present invention, a batch reactor for treating wastewater including granules is provided, wherein the batch reactor is operated by including an inflow / outflow step of introducing wastewater from the bottom surface of the reactor and simultaneously discharging treated wastewater through a treated water outlet at the top of the reactor, and a step of reacting and treating wastewater within the reactor when the inflow / outflow step is completed.

[0028] As described above, according to one aspect of the present invention, by operating a batch partial nitrification process as a single unit cycle consisting of two stages—an inflow / outflow stage and a reaction stage—the processing time required for operating the unit cycle can be shortened. In addition, the inflow of untreated wastewater and the discharge of treated water after the reaction are carried out simultaneously, and the entire amount of treated water in the reaction tank is discharged after the unit cycle ends, thereby preventing the accumulation of solids in the reaction tank.

[0029] Furthermore, by controlling the inflow rate of wastewater entering the reactor, the size of the effective granules to be maintained within the reactor can be selected according to the reactor conditions and the characteristics of the inflowing wastewater, which has the advantage of achieving stable partial nitrification efficiency.

[0030] Figure 1 is a conceptual diagram showing the operation method of a typical batch reactor (SBR) applied to biological wastewater treatment using aerobic granular sludge (AGS).

[0031] FIG. 2 is a diagram illustrating the configuration of a nitrogen removal device in wastewater including a batch partial nitrification reactor according to one embodiment of the present invention.

[0032] FIG. 3 is a conceptual diagram showing the operation method of a batch partial nitrification reactor according to one embodiment of the present invention.

[0033] FIG. 4 is a conceptual diagram showing the movement of granules and flocs according to the inflow of wastewater during the inflow and outflow stages of a batch partial nitrification reactor according to one embodiment of the present invention.

[0034] Figure 5 is a graph showing the relationship between the time required for the discharge of flocs and the separation of granules inside the reactor and the upward flow caused by the inflow of wastewater in a batch partial nitrification reactor according to one embodiment of the present invention.

[0035] Figure 6 is the result of comparing the concentration of free ammonia (FA) in a reaction tank immediately after the completion of the wastewater inflow / outflow step according to the wastewater exchange ratio (ER) in a batch reaction tank according to one embodiment of the present invention.

[0036] The present invention is susceptible to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each drawing.

[0037] Terms such as first, second, A, B, etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0038] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0039] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" should be understood as not precluding the existence or addition of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains.

[0041] Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0042] In addition, each component, process, procedure, or method included in each embodiment of the present invention may be shared within a scope that is not technically contradictory to one another.

[0043] FIG. 2 is a diagram illustrating the configuration of a nitrogen removal device in wastewater including a batch partial nitrification reactor according to one embodiment of the present invention.

[0044] Referring to FIG. 2, a nitrogen removal device (100) in wastewater according to one embodiment of the present invention includes a batch partial nitrification reactor (110), a wastewater inlet (120), an inlet pump (125), a treated water outlet (130), an air supply means (not shown), a treated water storage tank (140), a baffle wall (145), a supernatant outlet (150), a sludge discharge section (160), and an anaerobic ammonium oxidation reactor (170).

[0045] A batch partial nitrification sequencing batch reactor (PN-SBR) (110) receives wastewater containing ammonia and performs a partial nitrification reaction, and discharges the treated water in which partial nitrification has been performed to a treated water storage tank (140).

[0046] The partial nitrification (PN) process focuses on the process of oxidizing ammoniacal nitrogen in raw water to nitrite nitrogen (NO2-N) using ammonia-oxidizing bacteria (AOB), taking into account the ammonia / alkalinity ratio.

[0047] The batch partial nitrification reactor (110) of the present invention performs partial nitrification using AOB granules, and the reactor (110) is operated by configuring two stages, a reaction stage and an inflow / outflow stage, into a single unit cycle. That is, it does not include a separate sedimentation stage, and after the completion of the reaction stage, the discharge of treated water and the inflow of untreated wastewater occur simultaneously. The operation stages of the reactor (110) will be described later in FIG. 2.

[0048] A batch partial nitrification reactor (110) receives wastewater that has undergone primary treatment from the outside and performs a partial nitrification reaction, thereby converting ammonia nitrogen (NH4-N) in the wastewater into nitrite nitrogen (NO2-N). The primary treated wastewater flowing into the batch partial nitrification reactor (110) may be effluent from an anaerobic digester, or wastewater containing high concentrations of nitrogen that has passed through a conventional biological reactor, or a mixture of these.

[0049] Wastewater flowing into the batch partial nitrification reactor (110) of the present invention flows in from the bottom of the reactor (110), and the inflow of wastewater and discharge of treated water within the reactor (110) are carried out in an upflow. The treated water, after the reaction is completed, is discharged to the treated water storage tank (140) from the upper side of the reactor (110).

[0050] To this end, the wastewater inlet (120) of the reaction tank (110) is positioned at the bottom of the reaction tank (110), and the treated water outlet (130) is positioned at the top of the reaction tank (110).

[0051] More specifically, the wastewater inlet (120) is positioned at the bottom of the reaction tank (110), that is, near the bottom surface of the reaction tank (110), and the wastewater that has been treated in the first stage is supplied into the reaction tank (110) by driving the inlet pump (125).

[0052] At this time, the wastewater inlet (120) supplies wastewater so that the wastewater introduced to the bottom surface of the reaction tank (110) forms an upward flow with a uniform flow velocity and uniform distribution over the entire cross-section of the reaction tank (110). While it is most desirable for the upward flow of untreated wastewater within the reaction tank (110) to form an ideal plug flow over the entire cross-section of the reaction tank, it is preferable to maintain a laminar flow state with almost no turbulence or at least a transitional flow (semi-laminar flow) state. For example, the flow of untreated wastewater within the reaction tank (110) can be maintained at a Reynolds Number (Re) of at least 3,000 or less, and it is more preferable for the Reynolds Number (Re) to be maintained at 2,300 or less.

[0053] To this end, the configuration of the wastewater inlet (120) can be applied without being limited to any type, as long as it is a structure capable of realizing a laminar flow state without causing plug flow or turbulence within the reaction tank (110).

[0054] As described above, the treated water outlet (130) is positioned at the top of the batch partial nitrification reactor (110) and discharges the treated water, after the reaction is completed, to the treated water storage unit (140).

[0055] The treated water outlet (130) may be formed at the upper part of the reaction tank (110), particularly near the effective surface of the wastewater in the reaction tank, and may include a plurality of outlets or be implemented as an overflow structure. However, it is not limited to this, provided that the discharge structure does not generate excessive turbulence in a direction perpendicular to the plug flow or laminar upward flow formed by the wastewater inlet (120).

[0056] However, local turbulence may be generated near the effective water surface of the reaction tank (110) by the treated water outlet (130), thereby forming a transitional flow (semi-laminar flow). In this case, the Reynolds number (Re) near the effective water surface of the reaction tank (110) may be 3,000 or less.

[0057] This slight local turbulence can break the interface between the untreated water and the treated water, which is maintained in a laminar state near the treated water outlet (130), and can be advantageous for discharging flocs located at the interface.

[0058] The batch-type partial nitrification reactor (110) may further include an air supply means (not shown).

[0059] An air supply means (not shown) supplies oxygen for a partial nitrification reaction during the reaction stage of the reaction vessel (110), and, if necessary, an air-lift type air supply device (not shown) that helps maintain the granules may be applied, but its configuration is not limited thereto.

[0060] The treated water storage tank (140) receives the treated water discharged through the treated water outlet (130) of the reaction tank (110) and temporarily stores it until it is supplied to the downstream anaerobic ammonium oxidation reaction tank (170). During the storage process, the treated water storage tank (140) settles and separates the flocs with low settling ability contained in the treated water received from the reaction tank (110), and discharges only the supernatant water to the downstream anaerobic ammonium oxidation reaction tank (170).

[0061] As mentioned above, it is generally advantageous to operate the partial nitrification reactor as a batch reactor (SBR).

[0062] On the other hand, the anaerobic ammonium oxidation (ANAMMOX) process located downstream of the nitrification process is highly sensitive to ammoniacal and nitrite nitrogen concentrations, so a continuous stirred tank reactor (CSTR) is more advantageous than a batch reactor.

[0063] Anaerobic ammonium oxidizing microorganisms have a relatively slow growth rate compared to other microorganisms, and in particular, the doubling time can take from 10 to 20 days, which is much longer than that of nitrifying microorganisms, which have a doubling time of about 1 day, or aerobic organic matter removal microorganisms, which have a doubling time of about 6 hours. Therefore, it is very important to secure a stable microbial concentration in the anaerobic ammonium oxidation process, and to this end, processes such as the Moving Bed Bioreactor (MBBR) using filter media or the Integrated Fixed Activated Sludge are mainly applied.

[0064] Generally, to connect the batch reactor (SBR) for the upstream partial nitrification process with the completely mixed reactor for the downstream anaerobic ammonium oxidation, a separate flow control tank is placed between the partial nitrification reactor and the anaerobic ammonium oxidation process to control the flow rate fluctuations of the entire process.

[0065] Accordingly, the treated water storage tank (140) receives the treated water from the batch partial nitrification reactor (110) and adjusts the flow rate so that the treated water is stably supplied to the downstream anaerobic ammonium oxidation reactor (170), and at the same time performs solid-liquid separation on the treated water from the partial nitrification reactor (110) to settle the floc discharged from the reactor (110) and discharge only the supernatant water to the downstream anaerobic ammonium oxidation reactor (170).

[0066] Generally, the time required for the partial nitrification reaction targeted in the batch reactor (110) varies depending on the characteristics of the incoming wastewater, but when anaerobic digester effluent is introduced, a reaction time of about 6 to 12 hours is required.

[0067] Accordingly, the treated water storage tank (140) can be designed with a capacity to store treated water for up to 12 hours. As a result, even flocs with poor settling properties can be sufficiently settled, so the treated water storage tank (140) can improve solid-liquid separation efficiency.

[0068] A baffle wall (145) is positioned on one side of the treated water storage tank (140) to prevent turbulence from occurring inside the storage tank (140) as treated water from the batch partial nitrification reactor (110) flows in all at once, thereby preventing the solid matter that has already settled from being refloated. To this end, it is preferable that the baffle wall (145) be positioned adjacent to the treated water inflow side of the treated water storage tank (140).

[0069] The baffle wall (145) controls the inflow speed and direction of the wastewater flowing into the treated water storage tank (140) all at once, thereby inducing the floc contained in the inflowing wastewater to settle effectively. The wastewater passing through the baffle wall (145) remains in the treated water storage tank (140) for a preset time, during which solid-liquid separation occurs, the supernatant moves to the top of the treated water storage tank (140) and is discharged, and the floc is collected at the bottom of the treated water storage tank (140).

[0070] The supernatant discharge section (150) is provided on the upper side opposite the inlet side of the treated water storage tank (140) to discharge wastewater, which has been separated from solids in the treated water storage tank (140), to the anaerobic ammonium oxidation reaction tank (170).

[0071] The sludge discharge section (160) is provided at the lower part opposite the inlet side of the treated water storage tank (140) to discharge solid matter settled in the treated water storage tank (140).

[0072] The bottom surface of the treated water storage tank (140) may be formed with a sloping structure so that solid matter settled in the treated water storage tank (140) can be effectively discharged through the sludge discharge section (160). In particular, the sloping structure of the bottom surface may be formed as a downward slope so that solid matter can be guided to the sludge discharge section (160), and may additionally include a separate sludge scraper (not shown) as needed.

[0073] At this time, the sludge discharge section (160) may be positioned at the lowest position below the treated water storage tank (140) to maximize discharge efficiency.

[0074] The anaerobic ammonium oxidation reactor (170) receives solid-liquid separated wastewater through the supernatant outflow section (150) of the treated water storage tank (140) and removes nitrogen from the wastewater.

[0075] The anaerobic ammonium oxidation reactor (170) contains Anammox microorganisms to induce the Anammox reaction. The Anammox reaction is a reaction in which Anammox microorganisms oxidize ammoniacal nitrogen into nitrite nitrogen under an anaerobic environment (oxygen-free environment). Accordingly, ammoniacal nitrogen is degassed into nitrogen gas, and nitrogen in the wastewater is removed. The Anammox reaction is as follows.

[0076] 1.0NH4 + +1.32NO2 - +0.066HCO3 - +0.13H + →1.02N2+0.26NO3 - +0.066CH2O 0.5 N 0.15 +2.03H2O

[0077] The anaerobic ammonium oxidation reactor (170) is operated as a completely mixed reactor (CSTR) as described above.

[0078] FIG. 3 is a conceptual diagram showing the operation method of a batch partial nitrification reactor according to one embodiment of the present invention.

[0079] Referring to FIG. 3, a batch partial nitrification reactor (110) according to one embodiment of the present invention is operated in an inflow / outflow phase-reaction phase, in which wastewater is first introduced into the reactor (110), undergoes a reaction phase for a preset time, and after the reaction is completed, the discharge of treated water and the inflow of new wastewater are performed simultaneously.

[0080] In the reaction stage, air is supplied for the oxidation reaction of ammonium, and the flow of granules and wastewater occurs within the reaction tank. When the reaction is completed after the preset reaction time has elapsed, granules and flocs are distributed at various heights within the effective water depth (H) within the reaction tank (110). At this time, the granules (G1, G2) have different settling velocities (V) depending on their size. G1 , V G2 It has ), and the flocs (F1, F2, F3) also have their own sedimentation velocity (V F1 , V F2 , V F3 has ).

[0081] Afterward, the inflow of wastewater begins from the bottom of the reaction tank (110) without a separate sedimentation process. At the same time, the treated wastewater is discharged from the top of the reaction tank (110). While the inflow of wastewater and the discharge of treated water occur simultaneously within the reaction tank (110), the flow of the treated water and the untreated wastewater is in a plug flow or laminar flow state. The interface between the treated water and the untreated wastewater is maintained in a laminar and transitional flow state to minimize mixing, and the water moves upward to the water surface of the effective depth (H) within the reaction tank (110).

[0082] At this time, the exchange ratio (ER) between the treated water and the untreated wastewater in the reaction tank may be at least 80%, preferably 100% or more. That is, the amount of treated water discharged from the reaction tank (110) after the end of a unit cycle in the batch partial nitrification reaction tank (110) of the present invention may be equal to or greater than the effective volume of the reaction tank. In addition, the exchange ratio (ER) of the wastewater does not exceed 130%, and is preferably at the level of 120%.

[0083] The exchange ratio (ER) between treated water and untreated wastewater in the batch partial nitrification reactor (110) can be determined based on the ratio of NO2 / NH4 of the treated water produced according to the alkalinity / ammonia ratio of the wastewater.

[0084] Therefore, as shown in Fig. 3, it is preferable that the wastewater applied in the reaction step after the inflow / outflow step be entirely untreated wastewater.

[0085] The batch reactor (110) of the present invention is configured to simultaneously carry out the inflow of wastewater and the discharge of treated water, and, unlike conventional batch reactors, to discharge the entire amount of treated water within the reactor. At the same time, the inflow rate of untreated wastewater is controlled so that granules with a high settling rate are retained within the reactor, and flocs with poor settling properties are discharged from the reactor (110) as the entire amount of treated water is discharged.

[0086] Upward flow velocity of wastewater flowing in (V wDue to this, the granules and flocs in the reaction tank (110) are subjected to a drag force moving upward. The movement of the granules and flocs resulting from this can be represented as the resultant force between the upward flow velocity and the settling velocity of each particle. Generally, granules with a settling velocity of 5 to 10 m / hr can be stably retained within the reaction tank regardless of their position within the reaction tank, even when considering the upward flow velocity, because their own settling velocity is greater than the upward flow velocity. Additionally, flocs with a low settling velocity can be discharged outside the reaction tank because their settling velocity is lower than the upward flow velocity.

[0087] However, in conventional batch reactors, the exchange ratio between treated water and untreated water is only 30 to 50%, so even if a separate sedimentation stage is performed, flocs located at the bottom of the reactor are still difficult to discharge to the outside.

[0088] Referring again to Figure 1 for a more specific look, when a short settling time of 30 minutes or less is applied, granules generally having a settling speed of 5 to 10 m / hr can move about 2.5 to 5 m during the settling process, while flocs known to have a settling speed of 1 to 2 m / hr can only move about 0.5 to 1.0 m. Therefore, during the settling process, granules move to the bottom of the reaction tank, and flocs remain in the supernatant and are discharged to the outside.

[0089] However, the flocs (F2, F3) located relatively at the bottom of the reaction tank (10) are located at the bottom of the supernatant discharge line during the sedimentation process and remain inside the reaction tank (10), as can be seen in the discharge and inflow stages of FIG. 1. For example, if the effective water depth (H) of the reaction tank is 4 m, the sedimentation time is 30 minutes, and the treated water exchange ratio (ER) is 50%, only 37.5% of the total flocs are discharged outside the reaction tank, and the remaining 62.5% of the flocs remain inside the reaction tank.

[0090] Referring again to FIG. 3, the batch partial nitrification reactor (110) of the present invention receives untreated water in a plug flow or a laminar flow state with almost no turbulence, and at the same time, the discharge volume of the discharged treated water maintains at least 100% of the effective volume of the reactor (110). Accordingly, after the reaction is completed, the flocs (F1, F2, F3) inside the reactor can all be discharged to the outside by the upward flow of the influent water, regardless of their location within the reactor (110). This will be examined in more detail in FIG. 4.

[0091] At this time, localized slight turbulence may occur in the upper region of the reaction tank (110) where the treated water outlet (130) is located. This slight turbulence disturbs the interface between the untreated water and the treated water, thereby solving the problem where low-settling flocs trapped at the interface cannot be discharged from the reaction tank (110).

[0092] FIG. 4 is a conceptual diagram showing the movement of granules and flocs following the inflow of wastewater during the inflow and outflow stages in a batch partial nitrification reactor according to one embodiment of the present invention.

[0093] Referring to FIG. 4, as wastewater flows into a batch partial nitrification reactor according to one embodiment of the present invention, the movement paths of granules (G1) located at the top of the reactor and flocs (F3) located at the bottom of the reactor are illustrated.

[0094] The incoming wastewater flows upward in a V w It moves at a flow velocity but remains in a laminar or transitional flow state. The granules are V', the resultant force of the upward flow velocity and the sedimentation velocity. G1 As a result, it moves to the bottom of the reaction tank. On the other hand, the floc (F3) located at the bottom of the reaction tank is V', which is the resultant force of the floc settling velocity and the upward flow velocity. F3It rises at a speed. At this time, floc (F3) that is close to the effective water surface of the reaction tank (110) can be discharged from the reaction tank (110) under the influence of slight turbulence that occurs locally near the treated water outlet (130).

[0095] As a result, the batch reactor (110) of the present invention can control the discharge of flocs within the reactor by controlling the supply speed and supply time of wastewater, and can select an appropriate granule size according to the condition of the reactor and the characteristics of the wastewater.

[0096] Figure 5 is a graph showing the relationship between the inflow time of wastewater required for the discharge of flocs inside the reactor and the separation of granules with respect to the upward flow caused by the inflow of wastewater in a batch partial nitrification reactor according to one embodiment of the present invention.

[0097] Figure 5a shows the feeding time required to discharge the floc (F3) located at the bottom of the reaction tank according to the inflow rate of wastewater in the reaction tank, and Figure 5b shows the relationship between the sedimentation rate of the granule (G1) located at the top of the reaction tank and the feeding time of the wastewater to maintain the granule in the reaction tank. In addition, the effective water depth (H) of the reaction tank was assumed to be 4 m, and the sedimentation rate of the floc (F3) itself was assumed to be 1 m / hr.

[0098] Referring to Fig. 5a, in order to discharge floc (F3) located at the bottom of the reaction tank with a settling speed of 1 m / hr to the outside of the reaction tank by plug flow, when the rising speed of the influent is 5 m / hr, the wastewater must be supplied for at least 60 minutes.

[0099] Meanwhile, since the batch reactor (110) of the present invention can control the rising flow rate of the incoming wastewater, the size of the granules to be maintained within the reactor can be selected according to the operating condition of the reactor.

[0100] If the condition of the granules deteriorates due to external influences, such as the influx of toxic substances, and granule disintegration occurs, the size of the granules decreases, resulting in a reduction in the settling rate. In this case, the outflow of granules can be prevented by lowering the inflow rate of wastewater. Additionally, the problem of excessive discharge of inoculated sludge can be resolved by lowering the inflow rate even before the granules are formed during the initial stages of operation.

[0101] In conventional batch reactors, the above problems were solved by adjusting the time of the sedimentation stage or through a separate sludge sorting process, but the batch partial nitrification reactor (110) of the present invention can perform the same function simply by adjusting the inflow rate of wastewater.

[0102] Referring to Fig. 5b, the inflow time of wastewater according to the sedimentation velocity of the granules for selecting the desired granule size is shown. That is, when the sum of the lowest sedimentation velocity of the granules themselves and the upward flow velocity at which the granules can be retained within the reaction tank is zero, the granules will not flow out of the reaction tank, so the inflow time of wastewater at the corresponding upward flow velocity was calculated.

[0103] For example, when attempting to retain granules larger than those with a settling velocity of 7 m / hr in a reaction tank, if the influent wastewater is supplied at an upward flow rate of 7 m / hr for at least 35 minutes to equal the volume of the effective volume of the reaction tank, all granules and flocs with a settling velocity lower than 7 m / hr can be discharged outside the reaction tank.

[0104] Meanwhile, the batch partial nitrification reactor (110) of the present invention can maintain an optimal NO2 / NH4 ratio in the downstream anaerobic ammonium oxidation reactor (170) by adjusting the exchange ratio (ER) of the treated water and the untreated wastewater and the inflow volume of the untreated wastewater according to the degree of partial nitrification reaction in the reactor (110).

[0105] As shown in the anaerobic ammonium oxidation reaction equation above, in the anaerobic ammonium oxidation reaction, it is most ideal to maintain a ratio of nitrite nitrogen to ammonia nitrogen of 1.32. However, depending on the reaction conditions in the anaerobic ammonium oxidation reactor (170), the ratio of nitrite nitrogen to ammonia nitrogen can be adjusted within the range of 1.0 to 1.5.

[0106] In conventional partial nitrification reactors, the above ratio is maintained by adjusting the reaction time. However, due to external environmental factors such as changes in the properties of the raw water and seasonal temperature fluctuations, it is difficult to maintain the above ratio solely by adjusting the reaction time.

[0107] However, the batch reactor (110) of the present invention controls the inflow and outflow rates of wastewater to maintain the ratio of nitrite nitrogen to ammonia nitrogen at a ratio of 1:1 to 1.5:1.

[0108] For example, if the reaction proceeds excessively and exceeds the range of the preset ratio, the influent wastewater may be introduced in an amount greater than the effective volume of the reaction tank to increase the concentration of ammonia discharged to the treated water storage tank (140). Since most of the nitrogen in the wastewater entering the reaction tank is ammonia nitrogen, if the influent water is discharged as is, the effect of increasing the concentration of ammonia occurs, thereby allowing the NO2 / NH4 ratio to be controlled in the downstream anaerobic ammonium oxidation reaction tank (170).

[0109] Through the flow rate control described above, the present invention enables stable process operation with simple flow rate control without the addition of additional equipment, in contrast to cases where ratio control is impossible or an operation method involving mixing raw water by additionally equipping a separate bypass facility, as is the case with conventional treatment plants.

[0110] In addition, the batch reactor (110) according to one embodiment of the present invention can stably maintain the concentration of active microorganisms in the reactor even when the concentration of solids in the incoming wastewater is high.

[0111] In the case of a typical batch reactor, that is, a reactor with an exchange rate of 30 to 50% for untreated wastewater, if the concentration of incoming solids (SS) increases, the separation efficiency between solids and active microorganisms decreases, and the proportion of active microorganisms decreases.

[0112] However, since the batch reactor (110) of the present invention discharges the entire amount of wastewater introduced into the reactor after the reaction is completed, it is possible to prevent the accumulation of solids within the reactor. That is, since the separation efficiency between general solids and granules, which are active microorganisms, can be maintained, even if a high concentration of solids is introduced temporarily, it can be effectively discharged from the reactor.

[0113] Furthermore, the batch partial nitrification reactor (110) according to one embodiment of the present invention can maintain a high level of free ammonia (FA) within the reactor (110), which is highly advantageous for performing a strong inhibitory reaction against nitrite-oxidizing bacteria (NOB). This is examined in detail in FIG. 6.

[0114] Figure 6 is the result of comparing the free ammonia concentration in the reactor immediately after the completion of the wastewater inflow / outflow step according to the wastewater exchange ratio in a batch reactor according to one embodiment of the present invention.

[0115] The inflow of wastewater into the reactor (110) was set to 30°C, pH 8.5, and ammonia concentration 1,000 mg / L, taking into account the effluent water quality of a typical anaerobic digester. After the completion of the partial nitrification reaction, the ratio of ammoniacal nitrogen to nitrite nitrogen was assumed to be 1:1, and calculations were performed for cases where the wastewater exchange ratio (ER) of the reactor was 50%, 70%, and 100%, respectively.

[0116] Referring to FIG. 6, when the exchange ratio (ER) is 100%, the entire amount of treated water after the reaction is completed is discharged from the reaction tank (110). Therefore, the ammonia concentration and pH in the reaction tank (110) at the time when the reaction starts in the next cycle after inflow / outflow are the same as the inflow water conditions. That is, when the pH of the inflow wastewater is 8.5, the ammonia concentration is 1,000 mg / L, and the temperature is 30℃, the FA in the reaction tank can be maintained at a high level of about 200 mgN / L.

[0117] On the other hand, when the exchange ratio is 70%, the FA concentration can be diluted to 25% of the FA concentration in the influent wastewater, and when the exchange ratio is 50%, it can be diluted to about 9%, so strong inhibition of NOB in the partial nitrification reaction cannot be achieved. Furthermore, since it is known that the inhibitory effect of NOB decreases as it adapts to the FA concentration during long-term operation, the present invention has the advantage of being able to sufficiently address this by maintaining the exchange ratio of the batch reactor at 100% or more.

[0118] The nitrogen removal device (100) in the wastewater of the present invention is configured as a partial nitrification reactor that simultaneously performs the inflow and discharge of wastewater based on plug flow, thereby allowing the desired granule size to be selectively selected by controlling the inflow rate of the incoming wastewater, and simultaneously, since the entire amount of floc in the reactor can be discharged, only the granules optimal for the reaction can be efficiently selected and maintained.

[0119] In addition, by discharging more than 100% of the reactants, including the treated water in the reactor, the free ammonia concentration in the reactor is maximized, and through this, microorganisms (NOB) that oxidize nitrite nitrogen can be effectively inhibited, thereby allowing the partial nitrification reaction to be performed stably. Furthermore, by utilizing the flow equalization tank located downstream as a means of solid-liquid separation to settle and separate poorly settled flocs discharged from the reactor, there is an advantage in that the inflow of solids into the downstream anaerobic ammonium oxidation reactor can be minimized.

[0120] The above description is merely an illustrative explanation of the technical concept of the present embodiment, and a person skilled in the art to which the present embodiment belongs would be able to make various modifications and variations within the scope of the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain, not limit, the technical concept of the present embodiment, and the scope of the technical concept of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present embodiment.

[0121]

[0122] CROSS-REFERENCE TO RELATED APPLICATION

[0123]

[0124] If this patent application claims priority under Section 119(a) of the U.S. Patent Act (35 USC § 119(a)) to Korean Patent Application No. 10-2024-0162093 filed on November 14, 2024, all of the contents thereof shall be incorporated into this patent application by reference. Furthermore, if this patent application claims priority in countries other than the United States for the same reasons as above, all of the contents thereof shall be incorporated into this patent application by reference.

Claims

1. A batch-type partial nitrification reactor that receives wastewater and performs a partial nitrification reaction to adjust the ammoniacal nitrogen and nitrite nitrogen in the wastewater to a preset ratio; A treated water storage tank that receives floc and treated water discharged from the above batch partial nitrification reactor and performs solid-liquid separation to separate the supernatant and solids; and It includes an anaerobic ammonium oxidation reactor that receives the supernatant from the above-mentioned treated water storage tank and removes ammoniacal nitrogen and nitrite nitrogen in the wastewater into nitrogen gas, and A nitrogen removal device for wastewater characterized by the above-mentioned batch partial nitrification reactor being operated in a wastewater inflow / outflow stage and a reaction stage.

2. In Paragraph 1, A nitrogen removal device for wastewater characterized by the above-mentioned batch partial nitrification reactor containing AOB granules inside, which is operated to ensure that only nitrification occurs.

3. In Paragraph 2, A device for removing nitrogen from wastewater, characterized in that the wastewater inflow / outflow stage of the batch partial nitrification reactor above involves the simultaneous inflow of untreated wastewater and the outflow of treated water after the reaction is completed in the batch partial nitrification reactor above.

4. In Paragraph 3, The above batch partial nitrification reactor is, A wastewater inlet is provided at the bottom of the reaction tank, and a treated water outlet is provided at the top of the reaction tank. A nitrogen removal device for wastewater, characterized in that the above-mentioned wastewater inlet supplies wastewater to move in a plug flow or an upward flow in a laminar state so that the untreated wastewater moves uniformly along the cross-section of the reaction tank.

5. In Paragraph 3, A nitrogen removal device for wastewater characterized in that, during the inflow / outflow stage of wastewater in the batch partial nitrification reactor, the untreated wastewater flowing in moves in an upward flow while maintaining the Reynolds number (Re) at 3000 or less so that the interface with the treated water already treated in the reactor is not excessively mixed.

6. In Paragraph 4, A nitrogen removal device for wastewater characterized in that the amount of treated water replaced within the reactor by untreated wastewater introduced during the inflow / outflow stage of the batch partial nitrification reactor is 80% to 120% of the effective volume of the reactor.

7. In Paragraph 1, The above batch partial nitrification reactor is, A nitrogen removal device for wastewater characterized by controlling the amount of discharged treated water to adjust the ratio of nitrite nitrogen to ammonia nitrogen to a preset range and supplying it to the anaerobic ammonium oxidation reactor.

8. In Paragraph 7, The above batch partial nitrification reactor is, A nitrogen removal device for wastewater characterized by controlling the nitrogen concentration in the wastewater flowing into the anaerobic ammonium oxidation reactor by adjusting the amount of water discharged to the treated water adjustment tank in the inflow / outflow stage to be greater than the effective volume of the reaction tank when the ratio of nitrite nitrogen to ammonia nitrogen in the treated water exceeds a preset range.

9. In Paragraph 2, The above batch partial nitrification reactor is, A nitrogen removal device for wastewater characterized by being able to select the size of granules retained in the reaction tank by changing the upward flow rate of the influent water in the reaction tank by adjusting the supply time of the wastewater supplied to the reaction tank in the above inflow / outflow stage.

10. A batch reactor for treating sewage and wastewater including granules, The above batch reactor is, An inflow / outflow step of introducing wastewater from the lower bottom surface of the reaction tank and simultaneously discharging the treated wastewater through the treated water outlet at the top of the reaction tank; and A batch reactor characterized by being operated including a step of reacting and treating wastewater within the reactor once the above inflow / outflow step is completed.

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