Longitudinal phase separation anaerobic reactor and methods and applications of use thereof

Abstract

The application discloses a longitudinal phase separation anaerobic reactor and a use method and application thereof, and the use method comprises the following steps: filling hydrolytic acidification granular sludge into a reactor body area below a first collecting cover, filling methanogenic granular sludge into the reactor body area between the first collecting cover and a second collecting cover, inputting wastewater and culture medium into the reactor body through a water inlet pipe, keeping hydraulic retention in the reactor body for at least 24 hours, starting the longitudinal phase separation anaerobic reactor in a step-by-step progressive manner, inputting wastewater into the reactor body through the water inlet pipe, and keeping hydraulic retention in the reactor body for at least 24 hours. The application has good applicability and treatment effect for treating high-concentration and refractory azo dye wastewater, guarantees stable effluent quality, and can obtain higher specific methanogenic activity and methane content in biogas.

Description

Technical Field

[0001] This invention belongs to the field of anaerobic reactor technology, specifically relating to a longitudinal phase separation anaerobic reactor and its usage and application. Background Technology

[0002] Anaerobic wastewater treatment processes are widely used in wastewater treatment due to their high load capacity, economic efficiency, and environmental friendliness. Simultaneously, the methane produced during the treatment process is an important clean energy source, crucial for achieving carbon neutrality and peak carbon emissions. To achieve high efficiency in anaerobic wastewater treatment, various classic anaerobic reactors, such as UASB, EGSB, and IC reactors, have been developed. However, conventional anaerobic reactors exhibit poor treatment efficiency and low methane yields for high-concentration, recalcitrant toxic wastewater. In recent years, to further improve the treatment efficiency and applicability of anaerobic reactors, novel improved anaerobic reactors, such as the controllable dual-cycle anaerobic reactor, have been developed.

[0003] The controllable dual-circulation anaerobic reactor (publication number: CN105753147A) is an improvement upon the internal circulation (IC) reactor. By adding an external controllable circulation device, it solves the problem of low biogas production preventing the initiation of internal circulation in the initial stage of IC reactor startup, thus improving the reactor's start-up efficiency and applicability to recalcitrant wastewater. However, the controllable dual-circulation anaerobic reactor still faces several technical bottlenecks, limiting its widespread application. First, it does not completely overcome the difficulties and slow start-up of traditional anaerobic reactors. Although it improves mass transfer efficiency, the reactor startup still depends on wastewater quality, just like the IC reactor, and reaching a stable operating period takes approximately three months. Second, when dealing with highly toxic wastewater such as landfill leachate, azo dye wastewater, and pesticide wastewater, even with external circulation devices to mitigate the impact of pollutants, the formation of granular sludge in the reaction zone is severely delayed or difficult, directly affecting the treatment efficiency and methane recovery rate of the controllable dual-circulation anaerobic reactor. Third, the controllable dual-cycle anaerobic reactor divides the reactor into two reaction zones without distinguishing them, and the second reaction zone is connected to the lower part, making it difficult for the second reaction zone to retain matching sludge, which greatly affects the treatment efficiency of the second reaction zone and reduces the space utilization rate of the reactor. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a longitudinal phase separation anaerobic reactor that achieves efficient degradation of various recalcitrant organic wastewaters and efficient biogas recovery within the anaerobic reactor. This reactor achieves relative phase separation between the acidification and methanogenesis stages through longitudinal partitioning, improves system stability and pollutant treatment efficiency through a two-phase circulation system, and shortens reactor start-up time through external sludge cultivation. It features a small footprint, short start-up time, easy control, and high treatment efficiency and energy recovery rate.

[0005] Another object of the present invention is to provide a method of using the above-mentioned longitudinal phase separation anaerobic reactor, which has a good degradation effect on azo dye wastewater.

[0006] Another object of the present invention is to provide the application of the above-described longitudinal phase separation anaerobic reactor in the degradation of azo dye wastewater.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A longitudinal phase separation anaerobic reactor includes: a reactor body, an inlet pipe, a first collection hood, a second collection hood, and a degassing tank. The reactor body is a sealed tank. The first collection hood is located below the second collection hood. Both the first and second collection hoods are installed inside the reactor body. A first sludge discharge port and an inlet are provided on the reactor body below the first collection hood. The inlet pipe is located outside the reactor body, and one end of the inlet pipe is connected to the inlet for feeding wastewater to be degraded into the reactor body. A second sludge discharge port is provided on the reactor body above the first collection hood.

[0009] The degassing tank is located above the reactor body. An exhaust port is formed on the degassing tank. A baffle is installed inside the degassing tank to divide it into a first space and a second space. A first riser pipe, a second riser pipe, a first return pipe, and a second return pipe are connected to the degassing tank. One end of the first return pipe and one end of the first riser pipe are respectively connected to the first space. One end of the second return pipe and one end of the second riser pipe are respectively connected to the second space. The other end of the first return pipe extends into the reactor body and is close to the bottom of the reactor body. A return inlet is formed on the reactor body between the first collection hood and the second collection hood. The other end of the second return pipe connects to the return... The inlet is connected, and the other end of the first riser pipe is connected to the upper part of the first collection hood, and a first pump is installed on the first riser pipe. The other end of the second riser pipe is connected to the upper part of the second collection hood, and a second pump is installed on the second riser pipe. Both the first and second collection hoods are tapered from bottom to top, and are used to sequentially guide the wastewater collected from the first and second collection hoods into the first and second riser pipes. A first gap is formed between the edge of the first collection hood and the inner wall of the reactor body, and a partition net is installed on the first gap. A second gap is formed between the edge of the second collection hood and the inner wall of the reactor body. An outlet pipe is connected to the reactor body above the second collection hood.

[0010] In the above technical solution, the separating mesh is 30 to 40 mesh.

[0011] The above technical solution also includes: a water distributor that is connected to the water inlet pipe and located inside the reactor body.

[0012] In the above technical solution, the first space and the second space are respectively connected to the exhaust port.

[0013] In the above technical solution, the lower part of the first space and the lower part of the second space are separated by the baffle, and the upper part of the first space and the upper part of the second space are connected.

[0014] In the above technical solution, the reflux inlet is located near the first collection hood.

[0015] In the above technical solution, the position where the first riser pipe is connected to the first space is higher than the position where the first return pipe is connected to the first space, and the position where the second riser pipe is connected to the second space is higher than the position where the second return pipe is connected to the second space.

[0016] In the above technical solution, the water outlet pipe is bent to form a water trap, which is used to form a water seal on the water outlet pipe.

[0017] In the above technical solution, a water outlet weir is installed on the inner wall of the reactor body, and the water outlet weir is connected to the water outlet pipe.

[0018] In the above technical solution, a heat insulation layer is installed around the reactor body.

[0019] In the above technical solution, the first return pipe passes through the first collection hood and the second collection hood.

[0020] The method of using a longitudinal phase separation anaerobic reactor includes the following steps:

[0021] Step 1: Hydrolyzed acidified granular sludge is filled into the reactor body area below the first collection hood through the first sludge discharge port, and methanogenic granular sludge is filled into the reactor body area between the first collection hood and the second collection hood through the second sludge discharge port. The volume of hydrolyzed acidified granular sludge filled in is 27-35% of the volume of the acid-producing phase, and the volume of methanogenic granular sludge filled in is 27-35% of the volume of the methanogenic phase.

[0022] Step 2: Introduce wastewater and culture medium into the reactor body through the inlet pipe, maintaining a hydraulic retention time of at least 24 hours. Start up the longitudinal phase separation anaerobic reactor using a step-by-step start-up method: Initially, introduce wastewater and culture medium at a volume ratio of (4.8–5.2):1. After the reactor body stabilizes, adjust the volume ratio to (9.8–10.2):1. After further stabilization, adjust to (19–22):1. After still stabilizing, adjust to (38–42):1. Once the reactor body is stable, stop introducing culture medium and only introduce wastewater. After the reactor body stabilizes, the start-up of the longitudinal phase separation anaerobic reactor is complete. Stable operation is defined as a COD treatment efficiency higher than 95% and a specific methane yield higher than 5 ml / g. During the start-up process of the longitudinal phase separation anaerobic reactor, the concentration ratio of COD in the wastewater, total nitrogen entering the reactor body and total phosphorus entering the reactor body is maintained at (310~290):5:1.

[0023] Step 3: Input wastewater into the reactor body through the inlet pipe and maintain the hydraulic retention in the reactor body for at least 24 hours.

[0024] A method for obtaining hydrolyzed acidified granular sludge includes the following steps:

[0025] S1. Prepare a culture medium based on the VSS concentration a mg / L in the anaerobic granular sludge. The culture medium includes a main component and a secondary component, and the ratio of the main component to the secondary component by volume is (980-1020):1. The main component is as follows:

[0026]

[0027] The excipients are as follows:

[0028]

[0029] S2. Sludge recovery: Anaerobic granular sludge is placed in a culture medium for acclimation at a temperature of 34-36℃ and a pH of 6.8-7.2. When the daily COD removal rate reaches more than 95%, sludge recovery is completed, and sludge culture medium is obtained. The ratio of culture medium to anaerobic granular sludge by volume is (1.8-2.2):1.

[0030] S3. Sludge acclimation: Add 2-bromoethane sulfonate (BES) to the sludge culture medium at a concentration of 48-52 mM to eliminate methanogenic bacteria in the sludge culture medium. At the same time, control the pH of the sludge culture medium to maintain at 5.6-5.8. When the daily volatile fatty acid production fluctuates by less than 5% and the proportion of each organic acid in the volatile fatty acids fluctuates by less than 5%, hydrolyzed acidified granular sludge is obtained.

[0031] A method for obtaining methanogenic granular sludge includes the following steps: anaerobic granular sludge is placed in a culture medium for acclimation, with the acclimation temperature maintained at 34–36°C and the pH maintained at 7.2–7.4. When the daily COD removal rate reaches more than 95% and the daily methane production fluctuates by less than 5%, methanogenic granular sludge is obtained. The ratio of culture medium to anaerobic granular sludge by volume is (1.8–2.2):1.

[0032] The method of using the longitudinal phase separation anaerobic reactor of this invention involves directly filling it with acclimated hydrolyzed acidified granular sludge and methanogenic granular sludge, enabling rapid start-up of the reactor. During wastewater treatment, the acid-producing and methanogenic phases are activated, improving mass transfer efficiency within the reactor while simultaneously diluting pollutant concentrations, ensuring efficient and stable operation. It exhibits good applicability and treatment effect for treating high-concentration, recalcitrant azo dye wastewater, ensuring stable effluent quality and achieving high specific methanogenic activity and methane content in biogas. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the longitudinal phase separation anaerobic reactor of the present invention;

[0034] Wherein, 1: reactor body, 2: degassing tank, 2-1: first space, 2-2: second space, 3: first collection hood, 4: partition net, 5: second collection hood, 6: baffle, 7: exhaust port, 8: first riser pipe, 9: first return pipe, 10: second riser pipe, 11: second return pipe, 12: sampling port, 13-1: first sludge discharge port, 13-2: second sludge discharge port, 14: water inlet pipe, 15: water distributor, 16: water outlet weir, 17: water outlet pipe, 18: water trap, 19: first pump, 20: second pump, 21: first material inlet, 22: second material inlet;

[0035] Figure 2 The decolorization rate of the longitudinal phase separation anaerobic reactor and the controllable double-circulation anaerobic reactor of the present invention;

[0036] Figure 3 The COD removal rate of the longitudinal phase separation anaerobic reactor and the controllable dual-circulation anaerobic reactor of the present invention;

[0037] Figure 4 The methane content in biogas from the longitudinal phase separation anaerobic reactor and the controllable double-circulation anaerobic reactor of the present invention;

[0038] Figure 5 This invention relates to the specific methanogenic activity of the longitudinal phase separation anaerobic reactor and the controllable dual-circulation anaerobic reactor. Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, a longitudinal phase separation anaerobic reactor includes: a reactor body 1, an inlet pipe 14, a first collection hood 3, a second collection hood 5, and a degassing tank 2. The reactor body 1 is a closed cylindrical tank. The first collection hood 3 is located below the second collection hood 5. Both the first collection hood 3 and the second collection hood 5 are installed inside the reactor body 1. A first sludge discharge port 13-1 and an inlet are provided on the reactor body 1 below the first collection hood 3. The inlet pipe 14 is located outside the reactor body 1, and one end of the inlet pipe 14 is connected to the inlet for inputting wastewater to be degraded into the reactor body 1. An inlet pump can be installed on the inlet pipe 14. A second sludge discharge port 13-2 is provided on the reactor body 1 above the first collection hood 3.

[0042] The degassing tank 2 is located above the reactor body 1. An exhaust port 7 is formed on the degassing tank 2. A baffle 6 is installed inside the degassing tank 2 to divide the interior into a first space 2-1 and a second space 2-2. The first space 2-1 can be approximately cylindrical, and the second space 2-2 can be an annular structure surrounding the first space 2-1. A first riser pipe 8, a second riser pipe 10, a first return pipe 9, and a second return pipe 11 are connected to the degassing tank 2. One end of the first return pipe 9 and one end of the first riser pipe 8 are respectively connected to the first space 2-1. One end of the second return pipe 11 and one end of the second riser pipe 10 are respectively connected to the second space 2-2. The other end of the first return pipe 9 extends into the reactor body 1 and is close to the bottom of the reactor body 1. A return flow is formed on the reactor body 1 between the first collection hood 3 and the second collection hood 5. The inlet and the other end of the second return pipe 11 are connected to the return inlet. The other end of the first riser pipe 8 is connected to the upper part of the first collection hood 3 and a first pump 19 is installed on the first riser pipe 8. The other end of the second riser pipe 10 is connected to the upper part of the second collection hood 5 and a second pump 20 is installed on the second riser pipe 10. The first collection hood 3 and the second collection hood 5 are both tapered from bottom to top, used to sequentially guide the wastewater collected from the first collection hood 3 and the second collection hood 5 into the first riser pipe 8 and the second riser pipe 10. A first gap is formed between the edge of the first collection hood 3 and the inner wall of the reactor body 1, and a separator 4 is installed on the first gap. The separator 4 can be a 35-mesh nylon mesh. A second gap is formed between the edge of the second collection hood 5 and the inner wall of the reactor body 1. An outlet pipe 17 is connected to the reactor body 1 above the second collection hood 5.

[0043] The region of reactor body 1 below the first collection hood 3 constitutes an acid-producing phase, while the region of reactor body 1 between the first collection hood 3 and the second collection hood 5 constitutes a methanogenic phase.

[0044] The longitudinal phase separation anaerobic reactor of the present invention has a small footprint, simple structure, and is easy to operate.

[0045] Example 2

[0046] Based on Example 1, it also includes a water distributor 15 that is connected to the water inlet pipe 14 and located inside the reactor body 1.

[0047] The first space 2-1 and the second space 2-2 are respectively connected to the exhaust port 7, which is used to lead to the outside of the degassing tank 2.

[0048] The lower part of the first space 2-1 and the lower part of the second space 2-2 are separated by a baffle 6, while the upper part of the first space 2-1 and the upper part of the second space 2-2 are connected.

[0049] The reflux inlet is located near the first collection hood 3.

[0050] The position where the first riser pipe 8 is connected to the first space 2-1 is higher than the position where the first return pipe 9 is connected to the first space 2-1, and the position where the second riser pipe 10 is connected to the second space 2-2 is higher than the position where the second return pipe 11 is connected to the second space 2-2.

[0051] The outlet pipe 17 is bent to form a water trap 18, which is used to form a water seal on the outlet pipe 17.

[0052] An outlet weir 16 is installed on the inner wall of the reactor body 1, and the outlet weir 16 is connected to the outlet pipe 17.

[0053] A first material inlet 21 is formed on the reactor body 1 below the first collection hood 3, and a second material inlet 22 is formed on the reactor body 1 between the first collection hood 3 and the second collection hood 5. A first valve is installed on the first material inlet 21, and a second valve is installed on the second material inlet 22. Other required substances can be introduced into the first material inlet 21 and the second material inlet 22.

[0054] An insulation layer (not shown in the figure) is installed around the reactor body 1. The insulation layer is a jacket through which hot water is introduced to regulate the temperature inside the reactor body 1. The insulation layer is less affected by the external temperature and can meet the usage requirements of different regions and seasons.

[0055] The first return pipe 9 passes through the first collection shroud 3 and the second collection shroud 5.

[0056] A sampling port 12 is formed on the reactor body 1 below the first collection hood 3.

[0057] Water quality monitoring probes are installed on the reactor body 1 of the acid-producing phase and the methanogenic phase, respectively, to monitor the physicochemical indicators of the wastewater in the corresponding acid-producing phase and methanogenic phase.

[0058] Temperature monitoring devices are installed on the reactor body 1 for both the acid-producing phase and the methanogenic phase.

[0059] Example 3

[0060] The method of using the above-mentioned longitudinal phase separation anaerobic reactor includes the following steps:

[0061] Step 1: Hydrolyzed acidified granular sludge is filled into the reactor body 1 area below the first collection hood 3 through the first sludge discharge port 13-1, and methanogenic granular sludge is filled into the reactor body 1 area between the first collection hood 3 and the second collection hood 5 through the second sludge discharge port 13-2. The volume of hydrolyzed acidified granular sludge filled in is 30% of the volume of the acid-producing phase, and the volume of methanogenic granular sludge filled in is 30% of the volume of the methanogenic phase.

[0062] Step 2: Wastewater and culture medium are introduced into reactor body 1 through inlet pipe 14, maintaining a hydraulic retention time of 24 hours. The longitudinal phase separation anaerobic reactor is started up using a step-by-step start-up method: initially, the volume ratio of wastewater to culture medium is 5:1. After stable operation in reactor body 1, the volume ratio is adjusted to 10:1. After stable operation in reactor body 1, the volume ratio is adjusted to 20:1. After stable operation in reactor body 1, the volume ratio is adjusted to 40:1. After stable operation in reactor body 1, no more culture medium is introduced into reactor body 1, only wastewater. After stable operation in reactor body 1, the start-up of the longitudinal phase separation anaerobic reactor is complete. Stable operation is defined as a COD treatment efficiency higher than 95% and a specific methane yield higher than 5 ml / g. During the start-up process of the longitudinal phase separation anaerobic reactor, the concentration ratio of COD in the wastewater, total nitrogen entering reactor body 1, and total phosphorus entering reactor body 1 is maintained at 300:5:1.

[0063] Step 3, formal degradation: Wastewater is introduced into reactor body 1 through inlet pipe 14, and the hydraulic retention in reactor body 1 is maintained for 24 hours.

[0064] In this example, the longitudinal phase separation anaerobic reactor operates as follows: wastewater enters the distributor 15 via the inlet pump, where it is evenly distributed at the bottom of the acid-producing phase and mixed uniformly with the hydrolyzed acidified granular sludge. The biogas generated in the acid-producing phase is collected by the first collection hood 3 and sent to the degassing tank 2. After the wastewater flows upward to the first collection hood 3, a portion of the wastewater is lifted to the degassing tank 2 via the first riser pipe 8 by the first pump 19 to complete gas-liquid separation. The gas is collected, and the wastewater is returned to the bottom of the acid-producing phase via the first return pipe 9 under gravity, diluting the wastewater entering through the inlet pipe 14 and improving the mass transfer rate. After passing through the acid-producing phase, the wastewater flowing to the methanogenic phase mixes with the methanogenic granular sludge, generating a large amount of biogas. This biogas is collected in the degassing tank 2 through the second collection hood 5. After the wastewater flows to the second collection hood 5, part of the sludge-water mixture, driven by the biogas and the second pump 20, is lifted to the degassing tank 2 through the second riser pipe 10 to complete gas-liquid separation and gas collection. The sludge-water mixture, under gravity, flows back to the bottom of the methanogenic phase through the second return pipe 11, completing wastewater dilution and circulating mass transfer. The remaining wastewater flows upward and undergoes sedimentation in the upper part of the second collection hood 5. The settled sludge returns to the methanogenic phase. The treated wastewater is discharged through the effluent weir 16 and the water trap 18, and then discharged along the effluent pipe 17.

[0065] A method for obtaining hydrolyzed acidified granular sludge includes the following steps:

[0066] S1. Prepare the culture medium according to the concentration of VSS (volatile suspended solids) in anaerobic granular sludge, a mg / L. The culture medium includes a main component and a secondary component. By volume, the ratio of the main component to the secondary component is 1000:1. The main components are shown in Table 1, and the secondary components are shown in Table 2.

[0067] Table 1

[0068]

[0069]

[0070] The concentration of sodium bicarbonate in Table 1 does not change with the mass of VSS, but remains at 3000 mg / L, mainly as a buffer to maintain the pH during the reaction.

[0071] Table 2

[0072] Excipients Concentration (mg / L) Ferrous chloride tetrahydrate 2000 Cobalt chloride hexahydrate 2000 Sodium selenose sulfate 162 Manganese chloride tetrahydrate 50 EDTA 1000 Copper chloride dihydrate 38 Nickel chloride hexahydrate 92 Zinc chloride 50 Aluminum chloride hexahydrate 90 Ammonium heptamolybdate tetrahydrate 50 boric acid 50 water -

[0073] The anaerobic granular sludge originates from the granular sludge in the UASB reactor used to treat dye wastewater.

[0074] S2. Sludge recovery: Anaerobic granular sludge is placed in a culture medium for acclimation at a temperature of 35°C and a pH of 6.5. When the daily COD removal rate reaches more than 95%, sludge recovery is completed, and sludge culture medium is obtained. The ratio of culture medium to anaerobic granular sludge by volume is 2:1.

[0075] S3. Sludge acclimation: Add 2-bromoethane sulfonate (BES) to the sludge culture medium at a concentration of 50 mM to eliminate methanogenic bacteria in the sludge culture medium. At the same time, control the pH of the sludge culture medium to maintain at 5.8. When the daily volatile fatty acid production fluctuates by less than 5% and the proportion of each organic acid in the volatile fatty acids fluctuates by less than 5%, hydrolyzed acidified granular sludge is obtained.

[0076] A method for obtaining methanogenic granular sludge includes the following steps: anaerobic granular sludge is placed in a culture medium for acclimation, the acclimation temperature is maintained at 35℃, the pH is maintained at 7.2, and when the daily COD removal rate reaches more than 95% and the daily methane production fluctuates less than 5%, methanogenic granular sludge is obtained, wherein the ratio of culture medium to anaerobic granular sludge by volume is 2:1.

[0077] Example 4

[0078] The longitudinal phase separation anaerobic reactor was operated according to the method described in Example 3, wherein the volume of the longitudinal phase separation anaerobic reactor was 2.5L, and a = 0.5. The wastewater came from the actual azo dye wastewater treatment of a dyeing and printing factory in Tianjin, with an azo dye content of approximately 200 mg / L. Tests showed that the time to obtain hydrolyzed acidified granular sludge and methanogenic granular sludge was 21 days each, and the start-up time of the longitudinal phase separation anaerobic reactor was 28 days.

[0079] After the longitudinal phase separation anaerobic reactor is started, a formal degradation process is carried out for 28 days.

[0080] Comparative Example 1

[0081] A controllable dual-cycle anaerobic reactor (the structure of which is shown in publication number CN105753147A, and all names below are the names in CN105753147A) has the same volume as the longitudinal phase separation anaerobic reactor in Example 4.

[0082] Since the wastewater treated by the technical solution in publication number CN105753147A is traditional Chinese medicine wastewater, the degradation of azo dye wastewater is more difficult than that of traditional Chinese medicine wastewater, and the device start-up time is longer. In order to compare the usage method protected by this invention with the usage method in publication number CN105753147A in terms of the degradation of azo dye wastewater, the azo dye wastewater will be treated according to the usage method in publication number CN105753147A, as follows:

[0083] A method for using a controllable dual-cycle anaerobic reactor includes the following steps:

[0084] Step 1: Inoculate the first reaction zone of the controllable dual-circulation anaerobic reactor with flocculent sludge from a municipal wastewater treatment plant that treats dye wastewater. The flocculent sludge accounts for 33% of the internal volume of the controllable dual-circulation anaerobic reactor.

[0085] Step 2: Wastewater of the same source and volume as in Example 4 is input into the controllable dual-circulation anaerobic reactor via an inlet pump and distributor, allowing the wastewater to mix evenly with the flocculent sludge. The biogas produced in the first reaction zone is collected by the primary three-phase separator. Since the biogas produced in the early stage of the reaction is insufficient to drive the internal circulation of the reactor, the valve on the internal circulation riser is closed, while the two valves on the internal circulation conversion pipe are opened and the internal circulation control pump is turned on. The internal circulation control pump drives the gas-liquid mixture in the pipeline to the inner layer of the degassing tank. The separated biogas is discharged from the top of the degassing tank, and the sludge-water mixture returns to the bottom of the first reaction zone along the internal circulation downcomer, completing the controllable internal circulation. After treatment in the first reaction zone, the wastewater automatically enters the second reaction zone for further treatment. The biogas produced in the second reaction zone is collected by a two-stage three-phase separator. Since the biogas produced in the early stage of the reaction is insufficient to drive the external circulation, the valve on the external circulation riser pipe is closed, while the two valves on the external circulation conversion pipe are opened, and the external circulation control pump is activated. The external circulation control pump drives the gas-liquid mixture in the pipeline to the outer layer of the degassing tank. The separated biogas is discharged from the top of the degassing tank, and the mud-water mixture returns to the bottom of the second reaction zone along the internal circulation downcomer, completing the controlled external circulation. In the sedimentation zone, the mud-water mixture undergoes solid-liquid separation. The treated wastewater supernatant is discharged through the effluent weir and effluent pipe, while the settled sludge is returned to the second reaction zone.

[0086] Step 3: After 110 days of reaction, due to the high mass transfer efficiency of the dual-circulation anaerobic reactor, the flocculent sludge in the reactor gradually forms granular sludge, and the wastewater treatment efficiency tends to stabilize, completing the reactor startup. Simultaneously, biogas production gradually increases. When the biogas is sufficient to drive both the internal and external circulation, the internal and external circulation control pumps are shut off, the valves on the internal and external circulation switching pipes are closed, and the valves on the internal and external circulation riser pipes are opened, achieving self-driven circulation in the reactor (at this point, the controllable dual-circulation anaerobic reactor startup is complete).

[0087] After the controllable dual-cycle anaerobic reactor is started up, a formal degradation process is carried out for 28 days: wastewater is input into the controllable dual-cycle anaerobic reactor and hydraulic retention is maintained for 24 hours.

[0088] The effects of the usage methods of the longitudinal phase separation anaerobic reactor in Example 4 and the controllable dual-circulation anaerobic reactor in Comparative Example 1 on the formal degradation during the 28-day period were tested respectively (during the formal degradation period, the daily influent volume of the longitudinal phase separation anaerobic reactor in Example 4 and the controllable dual-circulation anaerobic reactor in Comparative Example 1 was the same):

[0089] In terms of processing efficiency, the azo dye decolorization rate of the longitudinal phase separation anaerobic reactor of this invention remains stable at 72%–75%. Figure 2The COD removal rate of the longitudinal phase separation anaerobic reactor of this invention can reach up to 80%, which is 23.1% higher than that of the controllable dual-circulation anaerobic reactor. Therefore, for azo dye wastewater, the longitudinal phase separation anaerobic reactor of this invention has better operational stability. Figure 3 Furthermore, the controlled dual-cycle anaerobic reactor produces biogas with a methane content of 65%. The longitudinal phase separation anaerobic reactor of this invention achieves a higher methane purity in the biogas, reaching 74%, an increase of 12%, by performing anaerobic digestion within the same reaction system. Figure 4 Meanwhile, the methanogenic sludge specific methanogenic activity (SMA) of the longitudinal phase separation anaerobic reactor of this invention reaches 7.5 (ml / (gVSS·h)), which is 7.7% higher than that of the sludge in the controllable dual-cycle anaerobic reactor. This is also consistent with the higher methane yield obtained by the longitudinal phase separation anaerobic reactor. Figure 5 Therefore, it can be seen that the longitudinal phase separation anaerobic reactor of the present invention has achieved a significant improvement in the degradation effect on azo dye wastewater through adjustments to its mechanical structure and improvements in its usage method.

[0090] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method of using a longitudinal phase separation anaerobic reactor, the longitudinal phase separation anaerobic reactor comprising: The reactor body (1), inlet pipe (14), first collection hood (3), second collection hood (5), and degassing tank (2) are provided. The reactor body (1) is a sealed tank. The first collection hood (3) is located below the second collection hood (5). Both the first collection hood (3) and the second collection hood (5) are installed inside the reactor body (1). A first sludge discharge port (13-1) and an inlet are provided on the reactor body (1) below the first collection hood (3). The inlet pipe (14) is located outside the reactor body (1), and one end of the inlet pipe (14) is connected to the inlet for inputting wastewater to be degraded into the reactor body (1). A second sludge discharge port (13-2) is provided on the reactor body (1) above the first collection hood (3). The degassing tank (2) is located above the reactor body (1). An exhaust port (7) is formed on the degassing tank (2). A baffle (6) is installed inside the degassing tank (2) to divide the interior of the degassing tank (2) into a first space (2-1) and a second space (2-2). A first riser pipe (8), a second riser pipe (10), a first return pipe (9), and a second return pipe (11) are connected to the degassing tank (2). One end of the first return pipe (9) and one end of the first riser pipe (8) are respectively connected to the first space (2-1) and the second space (2-2). 1) One end of the second reflux pipe (11) and one end of the second riser pipe (10) are respectively connected to the second space (2-2). The other end of the first reflux pipe (9) extends into the reactor body (1) and is close to the bottom of the reactor body (1). A reflux inlet is formed on the reactor body (1) between the first collection hood (3) and the second collection hood (5). The other end of the second reflux pipe (11) is connected to the reflux inlet. The other end of the first riser pipe (8) is connected to the upper part of the first collection hood (3). A first pump (19) is installed on the first riser pipe (8), and the other end of the second riser pipe (10) is connected to the upper part of the second collection hood (5), and a second pump (20) is installed on the second riser pipe (10). The first collection hood (3) and the second collection hood (5) are both tapering from bottom to top, used to sequentially guide the wastewater collected from the first collection hood (3) and the second collection hood (5) into the first riser pipe (8) and the second riser pipe (10). The edge of the second collection hood (5) is flush with the inner wall of the reactor body (1). A second gap is formed between the first collection hood (3) and the inner wall of the reactor body (1) above the second collection hood (5). A water outlet pipe (17) is connected to the reactor body (1) above the second collection hood (5). The first gap is formed between the edge of the first collection hood (3) and the inner wall of the reactor body (1), and a partition net (4) is installed on the first gap. An acid-producing phase is formed in the region of the reactor body (1) below the first collection hood (3), and a methanogenic phase is formed in the region of the reactor body (1) between the first collection hood (3) and the second collection hood (5). The method of using the longitudinal phase separation anaerobic reactor includes the following steps: Step 1: Fill the area of ​​the reactor body (1) below the first collection hood (3) with hydrolyzed acidified granular sludge, and fill the area of ​​the reactor body (1) between the first collection hood (3) and the second collection hood (5) with methanogenic granular sludge. Step 2: Wastewater and culture medium are introduced into the reactor body (1) through the inlet pipe (14), maintaining a hydraulic retention time of at least 24 hours in the reactor body (1). The longitudinal phase separation anaerobic reactor is started up using a step-by-step start-up method: First, the volume ratio of wastewater to culture medium is (4.8-5.2):

1. After the reactor body (1) is running stably, the volume ratio of wastewater to culture medium is adjusted to (9.8-10.2):

1. After the reactor body (1) is running stably, the volume ratio of wastewater to culture medium is adjusted to (19-22):

1. After the reactor body (1) is running stably, the wastewater and culture medium are introduced into the reactor body (1) through the inlet pipe (14), maintaining a hydraulic retention time of at least 24 hours in the reactor body (1). The longitudinal phase separation anaerobic reactor is started up using a step-by-step start-up method: First, the volume ratio of wastewater to culture medium is (4.8-5.2):

1. After the reactor body (1) is running stably, the volume ratio of wastewater to culture medium is adjusted to (19-22):

1. After the reactor body (1) is running stably, the wastewater and culture medium are introduced into the reactor body (1). The volume ratio of wastewater to culture medium is adjusted to (38-42):

1. After the reactor body (1) is running stably, no more culture medium is input into the reactor body (1), only wastewater is input. After the reactor body (1) is running stably, the start-up of the longitudinal phase separation anaerobic reactor is completed. The operation is stable when the COD treatment efficiency is higher than 95% and the specific methane yield is higher than 5 ml / gVSS·h. During the start-up of the longitudinal phase separation anaerobic reactor, the concentration ratio of COD in wastewater, total nitrogen entering the reactor body (1) and total phosphorus entering the reactor body (1) is maintained at (310-290):5:

1. Step 3: Input wastewater into reactor body (1) through inlet pipe (14) and maintain hydraulic retention in reactor body (1) for at least 24 hours.

2. The method of use according to claim 1, characterized in that, The method for obtaining the hydrolyzed acidified granular sludge includes the following steps: S1. Prepare the culture medium; S2. Sludge recovery: Anaerobic granular sludge is placed in a culture medium for acclimation at a temperature of 34-36℃ and a pH of 6.8-7.

2. When the daily COD removal rate reaches more than 95%, sludge recovery is completed, and sludge culture medium is obtained. The ratio of culture medium to anaerobic granular sludge by volume is (1.8-2.2):

1. S3. Sludge acclimation: Add 2-bromoethane sulfonate to the sludge culture medium at a concentration of 48-52 mM to eliminate methanogenic bacteria in the sludge culture medium. At the same time, control the pH of the sludge culture medium to maintain at 5.6-5.

8. When the daily volatile fatty acid production fluctuates by less than 5% and the proportion of each organic acid in the volatile fatty acid fluctuates by less than 5%, hydrolyzed acidified granular sludge is obtained.

3. The method of use according to claim 1, characterized in that, The method for obtaining methanogenic granular sludge includes the following steps: anaerobic granular sludge is placed in a culture medium for acclimatization, with the acclimatization temperature maintained at 34–36℃ and the pH maintained at 7.2–7.

4. When the daily COD removal rate reaches more than 95% and the daily methane production fluctuates by less than 5%, methanogenic granular sludge is obtained. The ratio of culture medium to anaerobic granular sludge by volume is (1.8–2.2):

1.

4. The method of use according to claim 3 or 2, characterized in that, The culture medium was prepared according to the VSS concentration (amg / L) in the anaerobic granular sludge. The culture medium consisted of a main component and a secondary component, with a volume ratio of (980–1020):

1. The main component is as follows: The excipients are as follows:

5. The method of use according to claim 4, characterized in that, The separating mesh (4) has a mesh size of 30 to 40.

6. The method of use according to claim 1, characterized in that, It also includes: a water distributor (15) that is connected to the water inlet pipe (14) and located inside the reactor body (1); The first space (2-1) and the second space (2-2) are respectively connected to the exhaust port (7).

7. The method of use according to claim 6, characterized in that, The reflux inlet is located near the first collection hood (3).

8. The method of use according to claim 6, characterized in that, The lower part of the first space (2-1) and the lower part of the second space (2-2) are separated by the baffle (6), and the upper part of the first space (2-1) and the upper part of the second space (2-2) are connected; The position where the first riser (8) is connected to the first space (2-1) is higher than the position where the first return pipe (9) is connected to the first space (2-1), and the position where the second riser (10) is connected to the second space (2-2) is higher than the position where the second return pipe (11) is connected to the second space (2-2).

9. The method of use according to claim 3, characterized in that, The outlet pipe (17) is bent to form a water trap (18), which is used to form a water seal on the outlet pipe (17); A water outlet weir (16) is installed on the inner wall of the reactor body (1), and the water outlet weir (16) is connected to the water outlet pipe (17).

10. The method of use according to claim 1, characterized in that, An insulation layer is installed around the reactor body (1); the first reflux pipe (9) passes through the first collection hood (3) and the second collection hood (5).

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