A lateral flow step baffle anaerobic bioreactor and method

Abstract

This invention discloses a side-flow stepped baffle anaerobic bioreactor and method, belonging to the field of anaerobic biological wastewater treatment technology. The reactor body consists of interconnected preliminary reaction zone, intermediate reaction zone, final reaction zone, and three-phase separation zone, with adjacent reaction zones separated by stepped baffles. The stepped baffles form a stepped structure composed of parallel, spaced upper and lower horizontal baffles and vertically spaced longitudinal baffles. The upper and lower horizontal baffles are impermeable, while the longitudinal baffles have permeable holes to allow for lateral wastewater inflow and sludge retention in designated areas. Air inlets are located on the sidewalls of the preliminary and intermediate reaction zones, connected to a top exhaust pipe via an air inlet pipe on the outer wall of the reactor. This invention utilizes the stepped baffles to create a lateral flow path, reducing short-circuiting and dead zones, and lowering the risk of baffle clogging. The zoned design enhances sludge retention and improves anaerobic digestion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of anaerobic biological treatment technology for wastewater, specifically relating to a side-flow stepped baffle anaerobic bioreactor and method. Background Technology

[0002] Organic wastewater widely originates from industries such as food processing, pharmaceuticals, and livestock farming. It is characterized by high concentrations of organic matter and complex compositions, making it a significant target for water pollution control. Anaerobic biological treatment has become the preferred technology for treating organic wastewater due to its advantages, including no need for aeration, low energy consumption, minimal sludge production, and strong tolerance to high concentrations of organic matter.

[0003] Currently, commonly used reactors in anaerobic biological treatment, such as upflow anaerobic sludge blanket (UASB) and internal circulation anaerobic reactors (IC), struggle to simultaneously meet the growth requirements of microorganisms at different stages of anaerobic digestion, including hydrolysis and acidification, hydrogen and acetic acid production, and methanogenesis. When treating complex wastewater, these reactors also experience problems such as acidification instability caused by the accumulation of volatile fatty acids. While anaerobic baffled reactors (ABR) and two-phase anaerobic processes achieve functional zoning of the anaerobic stage through horizontal parallel or series tanks, they still suffer from bottlenecks such as low treatment efficiency. Existing vertically zoned reactors often employ horizontal baffles or longitudinally perforated structures. Under a single upward flow, sludge easily migrates across zones with the water flow, making it difficult to maintain the directional enrichment of microbial communities in each zone. Furthermore, the water flow direction of the longitudinally perforated structures is opposite to the settling direction of suspended solids, making them susceptible to impact clogging, creating dead zones, and limiting mass transfer efficiency.

[0004] To address the aforementioned issues, there is an urgent need to develop an anaerobic bioreactor and its treatment method that features clearly defined functional zones, stable sludge retention, anti-clogging properties, and efficient mass transfer, in order to improve the efficiency and operational stability of anaerobic biological treatment of complex organic wastewater. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a side-flow stepped baffle anaerobic bioreactor and method.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] In a first aspect, the present invention provides a side-flow stepped baffle anaerobic bioreactor, wherein the reactor body comprises, from bottom to top, interconnected preliminary reaction zone, intermediate reaction zone, final reaction zone, and three-phase separation zone; a first stepped baffle and a second stepped baffle with identical structures are respectively provided between the preliminary reaction zone and the intermediate reaction zone, and between the intermediate reaction zone and the final reaction zone; each of the first stepped baffle and the second stepped baffle includes a lower-level transverse baffle, an upper-level transverse baffle, and a longitudinal baffle vertically arranged between them, with the upper-level transverse baffle and the lower-level transverse baffle respectively located on opposite sides of the upper and lower ends of the longitudinal baffle, forming a stepped structure; the longitudinal baffle in the first stepped baffle and the second stepped baffle is provided with a plurality of water-permeable holes, while the lower-level transverse baffle and the upper-level transverse baffle are both water-impermeable structures.

[0008] The primary reaction zone and the advanced reaction zone of the reactor body are respectively provided with a first gas inlet and a second gas inlet for discharging reaction gases; a gas guide pipe is provided on the outside of the reactor body, which is connected to the first gas inlet and the second gas inlet respectively.

[0009] Preferably, the reactor body has a sludge discharge port at the bottom and an exhaust pipe at the top that connects to the gas collection channel in the three-phase separation zone; an outwardly inclined guide plate is provided at the bottom of the gas collection channel; a return water outlet pipe with a horizontal position higher than the guide plate is also provided on the side wall of the three-phase separation zone; the solid phase sedimentation zone in the three-phase separation zone is connected to the water outlet weir through a baffle plate; the bottom of the water outlet weir is inclined and the side wall has a water outlet; the side wall of the preliminary reaction zone of the reactor body is provided with a return water inlet pipe, a water inlet pipe and a first sludge inlet pipe; the side wall of the advanced reaction zone is provided with a first sludge discharge pipe and a second sludge inlet pipe; and the side wall of the final reaction zone is provided with a second sludge discharge pipe and a third sludge inlet pipe.

[0010] Furthermore, the first, second, and third mud inlet pipes are respectively located at half the vertical height of the primary reaction zone, intermediate reaction zone, and final reaction zone of the reactor body.

[0011] Furthermore, the inclination angle of the guide plate is set to 50°~60°; the inclination angle of the bottom of the outlet weir is set to 50°~60°.

[0012] Furthermore, the volume ratio of the preliminary reaction zone, the intermediate reaction zone, the final reaction zone, and the three-phase separation zone is (1~2):1:1:(2~4).

[0013] Furthermore, the diameter of the permeable holes is set to 2~4 mm.

[0014] Furthermore, in both the first and second stepped partitions, the ratio of the horizontal lengths of the upper and lower horizontal partitions is 1:(2~3).

[0015] Furthermore, the first stepped baffle and the second stepped baffle are respectively located at 1 / 3 and 2 / 3 of the vertical height of the reactor body.

[0016] Furthermore, the first air inlet and the second air inlet are respectively located below the upper horizontal partition of the first stepped partition and the second stepped partition, and the vertical distance between each of them and the upper horizontal partition is 1 / 4 to 1 / 3 of the height of the corresponding longitudinal partition.

[0017] Secondly, the present invention provides a method for using the side-flow stepped baffle anaerobic bioreactor described in the first aspect, the specific steps of which are as follows:

[0018] S1: Inoculate each reaction zone in the reactor body with anaerobic sludge. The anaerobic sludge is domesticated and enriched to form functional microbial communities under the separation and retention of the first and second step partitions.

[0019] S2: The wastewater to be treated enters the preliminary reaction zone for hydrolysis and acidification reaction, and the gas produced by the reaction is discharged through the first gas inlet; the treated wastewater flows laterally into the advanced reaction zone through the water permeable holes on the longitudinal partition in the first step partition, while the anaerobic sludge is retained in the preliminary reaction zone.

[0020] S3: The wastewater to be treated enters the advanced reaction zone to produce hydrogen and acetic acid. The gas produced by the reaction is discharged from the second gas inlet. After treatment, the wastewater flows laterally into the terminal reaction zone through the water permeable holes on the longitudinal partition in the second step partition, while the anaerobic sludge is retained in the advanced reaction zone.

[0021] S4: The wastewater to be treated enters the terminal reaction zone for methanogenesis, and the gas produced by the reaction enters the three-phase separation zone.

[0022] S5: Gases from the preliminary reaction zone and the advanced reaction zone converge into the gas guide pipe and are discharged from the top exhaust pipe; gas in the three-phase separation zone is introduced into the gas collection channel through the guide plate and is discharged from the exhaust pipe; part of the treated wastewater is returned to the preliminary reaction zone, and the rest is discharged through the effluent weir.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present invention divides the reactor longitudinally into multiple reaction zones by setting up stepped baffles, so that the sludge is stably retained in each reaction zone, avoiding back mixing of microorganisms and enriching anaerobic microorganisms with different functions in each reaction zone, realizing the stepwise degradation of organic matter in each reaction zone, and overcoming the problems of mutual interference between different functional microorganisms and accumulation of intermediate products in traditional reactors.

[0025] (2) The stepped baffle of the present invention turns the water flow from longitudinal upflow to transverse flow through the permeable holes of the longitudinal baffle, forming a lateral flow. The broken hydraulic path reduces short flow and dead zone in the reaction zone and improves the effective utilization rate of the reaction zone volume. Due to gravity, the granular sludge is difficult to turn with the water flow and pass through the horizontal permeable holes, which strengthens the sludge zoning retention effect.

[0026] (3) The partition and the permeable holes provided by the present invention are intersecting in direction. Under the action of gravity, the suspended sludge tends to settle longitudinally in the reaction zone, and it is not easy for sludge to accumulate in the horizontal direction, thereby reducing the risk of reactor blockage and extending service life.

[0027] (4) In this invention, the guide plate in the three-phase separation zone is connected to the gas collection channel, and the height of the return water outlet pipe is higher than that of the guide plate, which is conducive to the natural settling of sludge and the return of liquid phase, while reducing the risk of blockage of the return pipe.

[0028] Overall, the side-flow stepped baffle anaerobic bioreactor provided by this invention integrates reflux, sedimentation, gas collection, and reaction compartment separation into one unit. It has a compact structure, saves energy and reduces consumption, occupies a small area, and is suitable for efficient anaerobic biological treatment of organic wastewater. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the side-flow stepped baffle anaerobic bioreactor provided in this embodiment;

[0030] Figure 2 This is a partial enlarged view of the stepped partition installation location provided in this embodiment;

[0031] Figure 3 This is a schematic diagram of the longitudinal partition in the stepped partition provided in this embodiment;

[0032] Figure 4 for Figure 1 Cross-sectional view at point aa;

[0033] Figure 5 for Figure 1 Cross-sectional view at point bb;

[0034] In the diagram: 1. Sludge discharge port; 2. Water distributor; 3. Return water inlet pipe; 4. Water inlet pipe; 5. First sludge inlet pipe; 6. Preliminary reaction zone; 7. First step baffle; 7-1. First lower-level transverse baffle; 7-2. First longitudinal baffle; 7-3. First upper-level transverse baffle; 8. Second step baffle; 8-1. Second lower-level transverse baffle; 8-2. Second longitudinal baffle; 8-3. Second upper-level transverse baffle; 9. First sludge discharge pipe; 10. First air inlet; 11. Second sludge inlet pipe; 12. Advanced reaction zone; 13. Second air inlet; 14. Second sludge discharge pipe; 15. Air inlet pipe; 16. Third sludge inlet pipe; 17. Terminal reaction zone; 18. Guide plate; 19. Three-phase separation zone; 20. Gas collection channel; 21. Exhaust pipe; 22. Mud baffle; 23. Return water outlet pipe; 24. Water outlet weir; 25. Water outlet. Detailed Implementation

[0035] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0036] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0037] As a preferred embodiment of the present invention, this embodiment provides a side-flow stepped baffle anaerobic bioreactor, specifically including a reactor body, an air guide pipe 15, an effluent weir 24, and a first stepped baffle 7, a second stepped baffle 8, and an air collection channel 20 disposed within the reactor body.

[0038] As a preferred embodiment of the present invention, this embodiment provides a side-flow stepped baffle anaerobic bioreactor, specifically including a reactor body, an air guide pipe 15, an effluent weir 24, and a first stepped baffle 7, a second stepped baffle 8, and an air collection channel 20 disposed within the reactor body.

[0039] like Figure 1 , Figure 4 and Figure 5 As shown, the reactor body consists of interconnected preliminary reaction zone 6, intermediate reaction zone 12, final reaction zone 17, and three-phase separation zone 19, from bottom to top. In engineering applications, to accommodate the treatment of various complex organic wastewaters, the volume of each zone and the amount of inoculated sludge can be adjusted. The volume ratio of the preliminary reaction zone 6, intermediate reaction zone 12, final reaction zone 17, and three-phase separation zone 19 is set to (1~2):1:1:(2~4). The specific structure and connection methods of the device will be described below.

[0040] In the apparatus provided in this embodiment, the bottom of the preliminary reaction zone 6 of the reactor body has an arc-shaped structure, with a sludge discharge port 1 at its lowest point for periodically discharging sludge. The sidewall of the preliminary reaction zone 6 is also equipped with a return water inlet pipe 3, a water inlet pipe 4, a first sludge inlet pipe 5, and a first air inlet 10. It should be noted that in this embodiment, the return water inlet pipe 3 and the water inlet pipe 4 are positioned at the same horizontal height, while the first sludge inlet pipe 5 is positioned above the return water inlet pipe 3. A water distributor 2 is installed at the outlet end of the water inlet pipe 4 to evenly distribute the wastewater to be treated into the preliminary reaction zone 6. Furthermore, the first sludge inlet pipe 5 is positioned at 1 / 2 the height of the preliminary reaction zone 6. The first air inlet 10 is positioned below the first upper-level transverse partition 7-3 and is connected to the air inlet pipe 15 located on the outer wall of the reactor body. Preferably, the vertical distance between the first air inlet 10 and the first upper-level transverse partition 7-3 can be set to 1 / 4 to 1 / 3 of the height of the first longitudinal partition 7-2.

[0041] like Figure 2 As shown, in the device provided in this embodiment, a first stepped partition 7 for separating sludge is provided between the preliminary reaction zone 6 and the advanced reaction zone 12. The first stepped partition 7 is a stepped structure composed of a first lower-level transverse partition 7-1, a first upper-level transverse partition 7-3 arranged in parallel intervals, and a first longitudinal partition 7-2 arranged vertically between the first lower-level transverse partition 7-1 and the first upper-level transverse partition 7-3. The first lower-level transverse partition 7-1 and the first upper-level transverse partition 7-3 are respectively arranged on opposite sides of the upper and lower ends of the first longitudinal partition 7-2. A plurality of water-permeable holes are formed on the first longitudinal partition 7-2, specifically as shown in the figure. Figure 3 As shown. In this embodiment, the pore size of the permeable holes is set to 2 mm, which is sufficient to effectively trap anaerobic granular sludge.

[0042] In actual operation, the mud-water mixture after treatment in the preliminary reaction zone 6 flows upward, and the liquid also flows upward. After passing through the water permeable holes opened on the first longitudinal partition 7-2, it flows laterally into the advanced reaction zone 12, while the anaerobic sludge in it is intercepted by the first longitudinal partition 7-2, thereby realizing the separation and directional enrichment of sludge in different reaction zones.

[0043] Furthermore, the advanced reaction zone 12 of the reactor body is provided with a first sludge discharge pipe 9, a second sludge inlet pipe 11, and a second gas inlet 13 on its side wall. The second gas inlet 13 is located below the second upper-level transverse partition 8-3, and the vertical distance between the second gas inlet 13 and the second upper-level transverse partition 8-3 can be set to 1 / 4 to 1 / 3 of the height of the second longitudinal partition 8-2. The second gas inlet 13 is connected to a gas guide pipe 15 located on the outer wall of the reactor body. The gas generated after the reaction in the advanced reaction zone 12 enters the gas guide pipe 15 through the second gas inlet 13 and is transported upward.

[0044] The gas generated after the reaction in the preliminary reaction zone 6 enters the gas guide pipe 15 through the first gas guide port 10 and is transported upwards. The second sludge inlet pipe 11 is located above the first upper-level transverse partition 7-3, specifically at 1 / 2 the height of the advanced reaction zone 12. The first sludge discharge pipe 9 is located at the bottom of the side wall of the advanced reaction zone 12 to discharge the excess sludge generated in this area, thereby maintaining the balance of sludge volume within the system.

[0045] In the apparatus provided in this embodiment, a second stepped baffle 8 for separating sludge is also provided between the advanced reaction zone 12 and the terminal reaction zone 17. The second stepped baffle 8 has a similar structure to the first stepped baffle 7, consisting of a second lower-level transverse baffle 8-1, a second upper-level transverse baffle 8-3 arranged in parallel intervals, and a second longitudinal baffle 8-2 vertically arranged between the second lower-level transverse baffle 8-1 and the second upper-level transverse baffle 8-3, forming a stepped structure. Similarly, the second lower-level transverse baffle 8-1 and the second upper-level transverse baffle 8-3 are respectively arranged on opposite sides of the upper and lower ends of the second longitudinal baffle 8-2. The second longitudinal baffle 8-2 in the second stepped baffle 8 is also provided with several permeable holes with a diameter of 2 mm. It should be noted that when using other types of sludge, those skilled in the art can adjust the diameter of the permeable holes according to the sludge particle size.

[0046] Furthermore, a second sludge discharge pipe 14 and a third sludge inlet pipe 16 are provided on the side wall of the terminal reaction zone 17 of the reactor body. The second sludge discharge pipe 14 is located above the second lower-level transverse baffle 8-1 and is used to discharge the excess sludge generated in this area to maintain the sludge balance in the system. The third sludge inlet pipe 16 is located above the second upper-level transverse baffle 8-3, specifically at 1 / 2 the height of the terminal reaction zone 17, and is used to inoculate or replenish anaerobic sludge into the terminal reaction zone 17. An exhaust pipe 21 is provided at the top of the reactor body. The gas guide pipe 15 is connected to the first gas guide port 10 and the second gas guide port 13 respectively, extends vertically upward along the outer wall of the reactor to the top of the reactor body, and is connected to the exhaust pipe 21, so that the gas generated in the preliminary reaction zone 6 and the advanced reaction zone 12 is independently discharged to the top exhaust pipe 21 for unified discharge.

[0047] In the device provided in this embodiment, the top of the reactor body is a three-phase separation zone 19, and the gas collection channel 20 is disposed in this zone. The top of the gas collection channel 20 is connected to the exhaust pipe 21, and the bottom is provided with an outwardly inclined guide plate 18. It should be noted that the inclination angle α of the guide plate 18 can be set to 50°~60°. The connection between the bottom of the gas collection channel 20 and the guide plate 18 constitutes a solid phase sedimentation zone. The solid phase sedimentation zone has a downwardly tapering structure, and the sludge in this zone settles downward through the guide plate 18 and flows back to the end reaction zone 17. Preferably, in this embodiment, the centers of the water distributor 2, the gas collection channel 20, and the exhaust pipe 21 are located on the same vertical axis.

[0048] In addition, a return water pipe 23 is provided on the side wall of the three-phase separation zone 19 of the reactor body, and the horizontal position of the return water pipe 23 is higher than that of the guide plate 18. The return water pipe 23 is connected to the return water inlet pipe 3 in the preliminary reaction zone 6, forming an external circulation loop. The return water enters the preliminary reaction zone 6 through the return water inlet pipe 3, which can effectively reduce the impact of the inlet water load. The solid phase sedimentation zone in the three-phase separation zone 19 is connected to the effluent weir 24 through the baffle plate 22. The bottom of the effluent weir 24 is inclined, and the side wall is provided with an outlet 25. It should be noted that the inclination angle β of the bottom of the effluent weir 24 is set to 50°~60°.

[0049] Preferably, in this embodiment, the first stepped baffle 7 and the second stepped baffle 8 are respectively located at 1 / 3 and 2 / 3 of the vertical height of the reactor body. In the first stepped baffle 7, the ratio of the horizontal lengths of the first upper-level transverse baffle 7-3 and the first lower-level transverse baffle 7-1 is set to 1:2. Similarly, in the second stepped baffle 8, the ratio of the horizontal lengths of the second upper-level transverse baffle 8-3 and the second lower-level transverse baffle 8-1 is also set to 1:2. The first air inlet 10 and the second air inlet 13 are respectively located below the upper-level transverse baffles of the first stepped baffle 7 and the second stepped baffle 8, and the vertical distance between each of them and the upper-level transverse baffle is 1 / 4 to 1 / 3 of the height of the corresponding longitudinal baffle.

[0050] It should be noted that the material of the stepped baffle can be a hydrophilic material to further improve the wettability at the permeable holes; the size of the permeable holes on the longitudinal baffle can be flexibly selected according to the sludge properties and the characteristics of the wastewater to be treated.

[0051] The working principle of the anaerobic bioreactor provided by this invention is as follows:

[0052] The initial reaction zone is inoculated with anaerobic granular sludge or activated sludge (hereinafter collectively referred to as anaerobic sludge). Cellulose-decomposing bacteria, protease-decomposing bacteria, and lipase-decomposing bacteria in the sludge can hydrolyze the complex organic matter in the wastewater to be treated into amino acids, fatty acids, sugars, and alcohols. Subsequently, lactic acid-producing bacteria and propionic acid-producing bacteria ferment and produce acids, which are then converted into volatile fatty acids (acetic acid, propionic acid, butyric acid), hydrogen, and carbon dioxide under the action of intracellular enzymes.

[0053] Anaerobic sludge is also inoculated inside the advanced reaction zone. Unlike the preliminary reaction zone, after long-term zoned operation, the microbial community in the advanced reaction zone gradually specializes under the separation and retention effect of the stepped baffles. Acetic acid-producing bacteria are highly enriched and further decompose the volatile fatty acids produced in the preliminary reaction zone into acetic acid, hydrogen, and carbon dioxide.

[0054] Anaerobic sludge is inoculated inside the final reaction zone. Unlike the preliminary and intermediate reaction zones, methanogens are highly concentrated in the final reaction zone. Acetic acid and hydrogen produced from the preceding reactions of complex organic matter are further utilized by methanogens to generate methane. The gases produced in the final reaction zone rise directly into the three-phase separation zone. The final reaction zone serves two purposes: firstly, methanogens grow slowly, require a long time to reproduce, and have low resilience to environmental changes, making them vulnerable to the impact of complex and toxic organic wastewater. Placing it after the first two reaction zones allows the preceding reaction zones to treat most of the organic pollutants, thus alleviating the load pressure on the final reaction zone; secondly, the stepped baffles allow for the formation of internal circulation of anaerobic sludge within the zones, which is conducive to the formation of specific habitats for methanogens, improving gas production efficiency and the stability of the digestion process.

[0055] Next, this embodiment also provides a method for wastewater treatment using the above-mentioned side-flow stepped baffle anaerobic bioreactor, as detailed below:

[0056] S1: Anaerobic sludge is inoculated into the preliminary reaction zone 6, intermediate reaction zone 12, and final reaction zone 17 in the reactor body through the first sludge inlet pipe 5, the second sludge inlet pipe 11, and the third sludge inlet pipe 16, respectively. Under the separation and retention effect of the stepped baffles, the anaerobic sludge in each reaction zone is domesticated and enriched to form functional microbial communities adapted to the microenvironment of the corresponding reaction zone.

[0057] S2: The wastewater to be treated enters the preliminary reaction zone 6 through the inlet pipe 4 and the distributor 2 in sequence; the return water from the solid sedimentation zone enters the preliminary reaction zone 6 through the return inlet pipe 3; in the preliminary reaction zone 6, the organic matter in the wastewater to be treated is decomposed into volatile fatty acids and the like under the hydrolysis and acidification of anaerobic sludge, and the gas generated during the reaction rises and enters the gas guide pipe 15 through the first gas guide port 10;

[0058] S3: After being treated in the preliminary reaction zone 6, the wastewater flows laterally into the advanced reaction zone 12 through the permeable holes on the first longitudinal partition 7-2, while the anaerobic sludge is retained in the preliminary reaction zone 6. In the advanced reaction zone 12, the anaerobic sludge with hydrogen and acetic acid production functions converts the volatile fatty acids in the wastewater into acetic acid, hydrogen and some carbon dioxide. The gas generated during the reaction rises and enters the gas pipe 15 through the second gas inlet 13.

[0059] S4: The wastewater after being treated in the advanced reaction zone 12 flows laterally into the terminal reaction zone 17 through the permeable holes on the second longitudinal partition 8-2, while the anaerobic sludge is retained in the advanced reaction zone 12. In the terminal reaction zone 17, the acetic acid and hydrogen produced in the previous reaction produce methane under the action of the anaerobic sludge. The gas produced in the reaction process rises directly into the three-phase separation zone 19.

[0060] S5: Gases from the preliminary reaction zone 6 and the advanced reaction zone 12 converge at the first gas inlet 10 and the second gas inlet 13 respectively, and are discharged from the reactor through the top exhaust pipe 21. Gases entering the three-phase separation zone 19 are guided by the guide plate 18 into the gas collection channel 20 and are discharged through the exhaust pipe 21. Part of the treated wastewater is circulated back to the preliminary reaction zone 6 through the return water outlet pipe 23 and the return water inlet pipe 3, and the rest is discharged from the anaerobic bioreactor through the effluent weir 24 and the effluent outlet 25.

[0061] The main innovation of the device provided by this invention lies in the setting of the stepped baffles, the core functions of which are reflected in the following three aspects: 1) In terms of zoning, the reactor body is divided longitudinally into multiple relatively independent but interconnected reaction zones by the first and second stepped baffles, forming physical isolation between the zones, while achieving liquid interconnection through water permeable holes. During long-term operation, the anaerobic bacteria in each zone gradually accumulate in a directional manner under the interception effect of the stepped baffles, thereby constructing an anaerobic digestion chain with distinct functions such as hydrolysis and acidification, hydrogen and acetic acid production, and methanogenesis; 2) In terms of flow pattern, since the lower-level transverse baffles in the first and second stepped baffles are impermeable, the water flow direction is guided from vertical to lateral. The water flow must pass through the water permeable holes on the longitudinal baffles to form a lateral flow path before entering the next reaction zone. Granular sludge, due to gravity, tends to maintain vertical movement and is difficult to change direction with the water flow and pass through the horizontal permeable holes, thus being effectively retained in the original reaction zone, achieving separation of sludge from the water flow path; 3) In terms of anti-clogging, the longitudinal baffles are set vertically, and the permeable holes are opened horizontally. Suspended sludge settles vertically under gravity and is not easy to accumulate at the horizontal openings, significantly reducing the risk of baffle clogging and ensuring long-term mass transfer efficiency.

[0062] The anaerobic bioreactor provided by this invention divides the hydrolysis and acidification, hydrogen and acetic acid production, and methanogenesis processes into zones using stepped baffles. Complex organic matter, after decomposition, is sequentially utilized by cellulose-degrading bacteria, lactic acid-producing bacteria, acetic acid-producing bacteria, and methanogenic bacteria. Gases generated in each reaction zone are discharged through independent channels. After sedimentation in the solid-phase sedimentation zone, the sludge falls back to the final reaction zone via a guide plate, while a portion of the wastewater is returned to the initial reaction zone via a return effluent pipe for recycling, thus mitigating load shocks and achieving efficient pollutant removal. This stepped baffle design facilitates the enrichment of different functional microorganisms and the zoned retention of sludge, enabling the stepwise degradation of complex organic matter, significantly improving anaerobic treatment efficiency, and is suitable for treating various organic wastewaters.

[0063] Compared to existing UASB or IC-type anaerobic reactors that employ a single upflow path, this embodiment does not primarily rely on natural stratification within the overall sludge bed to complete the anaerobic digestion process. Instead, it vertically divides the reactor body into a preliminary reaction zone, an intermediate reaction zone, and a final reaction zone using first and second step partitions. The liquid phase then enters the next stage reaction zone laterally through permeable holes in the longitudinal partitions. Since both the lower and upper horizontal partitions are impermeable, the water flow is forced to change direction at the step partitions. The sludge primarily settles and remains within its original reaction zone due to gravity. Therefore, the structure structurally reduces the likelihood of sludge migrating across zones with the water flow, facilitating the directional enrichment of different functional anaerobic bacteria within each reaction zone.

[0064] Compared to ordinary horizontal perforated baffles or simple vertical partition structures, this embodiment places the permeable holes on the longitudinal baffles, with the flow direction of the orifices intersecting the main settling direction of the sludge. This prevents suspended sludge from forming a continuously compacted sludge layer at the orifices, thereby reducing the risk of baffle blockage and local short-circuiting. Compared to horizontal multi-compartment ABRs or two-phase anaerobic systems, this embodiment integrates hydrolysis acidification, hydrogen and acetic acid production, methanogenesis, sedimentation reflux, and gas collection and degassing functions within a single vertical reactor. This helps reduce external connecting pipelines and floor space, and minimizes the disturbance of intermediate gas production to the sludge layer in the subsequent reaction zone.

[0065] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A side-flow step baffle anaerobic bioreactor characterized in that, The reactor body consists of interconnected preliminary reaction zone, intermediate reaction zone, final reaction zone, and three-phase separation zone from bottom to top. Identical first-step and second-step partitions are installed between the preliminary reaction zone and the intermediate reaction zone, as well as between the intermediate reaction zone and the final reaction zone. Each of the first and second-step partitions includes a lower-level transverse partition, an upper-level transverse partition, and a vertically spaced longitudinal partition between them. The upper-level and lower-level transverse partitions are located on opposite sides of the upper and lower ends of the longitudinal partition, forming a stepped structure. The longitudinal partition in both the first and second-step partitions has several permeable holes, while the lower-level and upper-level transverse partitions are impermeable. The primary reaction zone and the advanced reaction zone of the reactor body are respectively provided with a first gas inlet and a second gas inlet for discharging reaction gases; a gas guide pipe is provided on the outside of the reactor body, which is connected to the first gas inlet and the second gas inlet respectively.

2. The side-flow stepped baffle anaerobic bioreactor according to claim 1, characterized in that, The reactor body has a sludge discharge port at the bottom and an exhaust pipe at the top that connects to the gas collection channel in the three-phase separation zone. An outwardly inclined guide plate is installed at the bottom of the gas collection channel. A return water outlet pipe, horizontally positioned higher than the guide plate, is also installed on the side wall of the three-phase separation zone. The solid sedimentation zone in the three-phase separation zone is connected to the effluent weir via a baffle plate. The effluent weir is inclined at the bottom and has an outlet on its side wall. A return water inlet pipe, an inlet pipe, and a first sludge inlet pipe are installed on the side wall of the preliminary reaction zone of the reactor body. A first sludge discharge pipe and a second sludge inlet pipe are installed on the side wall of the advanced reaction zone, and a second sludge discharge pipe and a third sludge inlet pipe are installed on the side wall of the final reaction zone.

3. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, The first, second, and third mud inlet pipes are respectively located at 1 / 2 vertical height of the primary reaction zone, intermediate reaction zone, and final reaction zone of the reactor body.

4. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, The inclination angle of the guide plate is set to 50°~60°; the inclination angle of the bottom of the outlet weir is set to 50°~60°.

5. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, The volume ratio of the preliminary reaction zone, the intermediate reaction zone, the final reaction zone, and the three-phase separation zone is (1~2):1:1:(2~4).

6. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, The diameter of the permeable holes is set to 2~4 mm.

7. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, In both the first and second step partitions, the ratio of the horizontal lengths of the upper and lower horizontal partitions is 1:(2~3).

8. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, The first and second stepped baffles are respectively located at 1 / 3 and 2 / 3 of the vertical height of the reactor body.

9. The side-flow stepped baffle anaerobic bioreactor according to claim 2, characterized in that, The first air inlet and the second air inlet are respectively located below the upper horizontal partition of the first stepped partition and the second stepped partition, and the vertical distance between each of them and the upper horizontal partition is 1 / 4 to 1 / 3 of the height of the corresponding longitudinal partition.

10. A method for using a side-flow stepped baffle anaerobic bioreactor according to any one of claims 2 to 9, characterized in that, The specific steps are as follows: S1: Inoculate each reaction zone in the reactor body with anaerobic sludge. The anaerobic sludge is domesticated and enriched to form functional microbial communities under the separation and retention of the first and second step partitions. S2: The wastewater to be treated enters the preliminary reaction zone for hydrolysis and acidification reaction, and the gas produced by the reaction is discharged through the first gas inlet; the treated wastewater flows laterally into the advanced reaction zone through the water permeable holes on the longitudinal partition in the first step partition, while the anaerobic sludge is retained in the preliminary reaction zone. S3: The wastewater to be treated enters the advanced reaction zone to produce hydrogen and acetic acid. The gas produced by the reaction is discharged from the second gas inlet. After treatment, the wastewater flows laterally into the terminal reaction zone through the water permeable holes on the longitudinal partition in the second step partition, while the anaerobic sludge is retained in the advanced reaction zone. S4: The wastewater to be treated enters the terminal reaction zone for methanogenesis, and the gas produced by the reaction enters the three-phase separation zone. S5: Gases from the preliminary reaction zone and the advanced reaction zone converge into the gas guide pipe and are then discharged from the top exhaust pipe; The gas in the three-phase separation zone is introduced into the gas collection channel through the guide plate and then discharged from the exhaust pipe. Part of the treated wastewater is returned to the preliminary reaction zone, while the remainder is discharged through the effluent weir.

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