A biofilm reactor for wastewater treatment system and hydrogen production

Abstract

The application belongs to the technical field of sewage treatment, and specifically discloses a biological membrane reactor for a sewage treatment system and hydrogen production, which comprises an ascending bed and a descending bed, the outlet end of the ascending bed is connected with the descending bed through a first reactor which is downwardly inclined, the outlet end of the descending bed is connected with the ascending bed through a second reactor which is upwardly inclined, and a circulating loop is formed, the flow direction of which is the ascending bed, the first reactor, the descending bed and the second reactor in sequence. The biological membrane reactor for the sewage treatment system and hydrogen production is used to optimize the hydrogen production performance of chemical substances in sewage by means of an external voltage, regulation and control of a fluid circulation path and fluidization speed, so that sewage purification and long-acting and stable production of biological hydrogen are simultaneously realized.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a biofilm reactor for wastewater treatment systems and hydrogen production. Background Technology

[0002] In traditional wastewater treatment processes, biological fluidized bed is a technology that combines the traditional activated sludge process and biofilm process, and introduces fluidization technology from chemical operations. It can decompose organic matter (such as glucose and starch) in wastewater to produce hydrogen gas, and has the advantages of high mass transfer efficiency and uniform liquid-solid phase contact.

[0003] In existing technologies, violent collisions between particles in the reactor can easily lead to particle aggregation and uneven distribution of reactants, which in turn causes imbalance in the liquid-solid two-phase mixing and inhibits the effective retention of particulate biomass, making it impossible to achieve long-term stable production of biohydrogen. Summary of the Invention

[0004] The purpose of this invention is to provide a biofilm reactor for wastewater treatment systems and hydrogen production, which optimizes hydrogen production performance by applying external voltage, regulating fluid circulation path and fluidization velocity, and achieving long-term stable production of biohydrogen.

[0005] To achieve the above objectives, the present invention provides a biofilm reactor for wastewater treatment systems and hydrogen production, comprising an ascending bed and a descending bed. The outlet end of the ascending bed is connected to the descending bed via a downwardly inclined first reactor, and the outlet end of the descending bed is connected to the ascending bed via an upwardly inclined second reactor, forming a circulation loop with the flow direction sequentially from the ascending bed to the first reactor, the descending bed, and the second reactor.

[0006] Both the first reactor and the second reactor are cylindrical structures, with the same volume, and the length of the first reactor is less than the length of the second reactor.

[0007] The ascending bed and the descending bed have the same structure. The ascending bed includes an outer shell and an inner shell. One end of the inner shell is fixedly connected to the inner wall of the outer shell. A carbon rod electrode is disposed at the center of the inner shell. The carbon rod electrode passes through the outer shell and is connected to a DC regulated power supply. Magnetite particles are filled between the carbon rod electrode and the inner shell. A cavity is formed between the outer shell and the inner shell. Several evenly spaced guide tubes are disposed in the cavity. Several perforated ring plates are disposed in the middle section of the guide tubes. Hydrogen-producing biofilm particles are filled in the guide tubes.

[0008] Preferably, the bottom of the ascending bed is provided with a first liquid inlet, and the bottom side wall of the descending bed is provided with a second liquid inlet. The first liquid inlet and the second liquid inlet are respectively connected to the guide pipe. The top of the ascending bed is provided with a first hydrogen port, and the top of the descending bed is provided with a second hydrogen port. The first hydrogen port and the second hydrogen port are respectively connected to the cavity.

[0009] The top side wall of the descending bed is provided with a first liquid outlet, and a second liquid outlet is provided below the first liquid outlet. The second liquid outlet is connected to the first liquid inlet through a first pipe. The first liquid outlet is connected to a clean water tank through a second pipe. A first branch and a second branch are arranged sequentially on the first pipe. The first branch is connected to a sewage tank and a feed pump. The second branch is connected to the second liquid inlet.

[0010] Preferably, the first hydrogen port and the second hydrogen port are respectively connected to a peristaltic pump, and the first pipeline is sequentially provided with a first electrically controlled valve, a circulation pump and a second electrically controlled valve. The inlet end of the second branch is located between the circulation pump and the second electrically controlled valve. The first branch is provided with a third electrically controlled valve and the second branch is provided with a fourth electrically controlled valve.

[0011] Preferably, the DC regulated power supply is electrically connected to the carbon rod electrode via a titanium wire to apply an external voltage. The carbon rod electrode serves as both the anode and cathode, and the circulation loop forms an electrolytic cell. The applied voltage of the DC regulated power supply is 0~1.2V.

[0012] Preferably, the applied voltage of the DC regulated power supply is 0.9V.

[0013] Preferably, the principle of the electrolytic cell is as follows: the hydrogen-producing biofilm particles on the anode feed on organic matter in the sewage through electrogenic microorganisms. During the metabolism, electrons are transferred to the anode and then reach the cathode through the titanium wire under the action of the potential difference of the DC regulated power supply. At the cathode, electrons combine with protons to produce hydrogen gas.

[0014] Preferably, both the circulating pump and the feed pump are connected to a signal generator, which is used to monitor the terminal fluidization velocity of the circulating loop, and the fluidization velocity is 1.1~1.3Ut.

[0015] Preferably, the fluidization rate is 1.2 Ut.

[0016] Preferably, the magnetite particles are 180mm nanometer-sized magnetite particles, and the inner shell has a mesh structure.

[0017] Preferably, the preparation of the hydrogen-producing biofilm particles specifically involves:

[0018] S1. Transfer PA6 particles to a high-pressure reactor, heat to 120~150℃ and 15~20MPa under nitrogen atmosphere, maintain pressure for 30~60min, and then rapidly depressurize at a depressurization rate of 5~30MPa / s to obtain modified PA6 particles.

[0019] S2. The bacteria were activated and cultured using Escherichia coli strains. After the bacteria were revived, they were transferred to the modified PA6 particles obtained in S1 for pre-culture to obtain carrier particles loaded with mature biofilms and bacterial suspension.

[0020] Preferably, the height of the riser bed is 5 to 15 times the inner diameter of the riser bed, and the inner diameter of the riser bed is 3 to 5 times the inner diameter of the guide pipe.

[0021] The present invention also provides a method of using a wastewater treatment system and a hydrogen-producing biofilm reactor, comprising the following steps:

[0022] T1. Transfer the hydrogen-producing biofilm particles into the guide tube, and then transfer the carbon rod electrode and magnetite particles into the inner shell in sequence. Purge the reactor system with nitrogen for 15 minutes, seal it, and establish an anaerobic environment.

[0023] T2. Start the feed pump to inject the sewage from the sewage tank into the riser bed until the sewage occupies 95-97% of the circulation loop volume, then turn off the feed pump.

[0024] T3. Start the peristaltic pump and circulation pump, open the first and fourth electrically controlled valves and the signal generator, and close the second and third electrically controlled valves. The circulation pump provides power for the liquid circulation within the circulation loop, allowing the liquid to reciprocate and circulate within the anaerobic circulating fluidized bed, forming a stable flow state. This allows wastewater and products from the electrolysis reaction to flow through the first pipe along a preset path (entering the circulation loop with the flow direction sequentially from the rising bed, the first reactor, the falling bed, and the second reactor. Simultaneously, in the rising and falling beds, in addition to the flow direction within the guide pipe synchronized with the circulation loop, there is also a flow direction of wastewater within the guide pipe along the mesh ring plate leading to the outside of the guide pipe. Furthermore, gas disturbance causes wastewater outside the guide pipe to flow into the guide pipe). In addition, the peristaltic pump is used to control gas delivery. After the reaction begins, the hydrogen generated during the flow process floats upwards and is collected by the peristaltic pump, the first hydrogen port, or the second hydrogen port, and then transported to the subsequent purification stage. The terminal fluidization velocity of the circulation loop is monitored using a signal generator. The obtained monitoring signal is used by a monitoring computer to obtain the rotational speed of the circulation pump and the flow rate of the first and fourth electrically controlled valves.

[0025] T4. Use a monitoring computer to record the applied voltage data and use a water quality tester to test the water quality of the sewage in the first pipeline. When the concentration of organic matter in the sewage meets the discharge standards, close the first and fourth electrically controlled valves, open the first outlet, and discharge the treated sewage into the clean water tank. After the sewage is discharged, close the first outlet and continue to replenish the first inlet with new sewage from the sewage tank and the feed pump to complete one cycle of sewage replacement.

[0026] Therefore, the present invention employs the above-mentioned biofilm reactor for wastewater treatment systems and hydrogen production, and the beneficial effects are as follows:

[0027] This invention coordinates external voltage, fluid circulation path regulation, and fluidization velocity to achieve a stable terminal fluidization velocity of 1.2Ut in an anaerobic environment by using a signal generator to control the flow rate of the first and fourth electrically controlled valves and the rotation speed of the circulation pump. Combined with an external voltage of 0.9V, this optimizes the hydrogen production performance of chemical substances in wastewater, simultaneously achieving wastewater purification and long-term stable production of biological hydrogen.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of an embodiment of a biofilm reactor for wastewater treatment system and hydrogen production according to the present invention;

[0030] Figure 2 This is a schematic diagram of the rising bed structure of an embodiment of a biofilm reactor for wastewater treatment system and hydrogen production according to the present invention;

[0031] Figure 3 This is a cross-sectional view of the rising bed of an embodiment of a biofilm reactor for wastewater treatment system and hydrogen production according to the present invention;

[0032] Figure 4 This is the glucose conversion result of an embodiment of the present invention for a wastewater treatment system and a biofilm reactor for hydrogen production;

[0033] Figure 5 This is the hydrogen content (HY) result of an embodiment of the present invention for a wastewater treatment system and a hydrogen-producing biofilm reactor;

[0034] Figure 6 This is the hydrogen production rate (HPR) result of an embodiment of the present invention for a wastewater treatment system and a hydrogen-producing biofilm reactor.

[0035] Figure Labels

[0036] 1. Ascending bed; 2. First reactor; 3. Descending bed; 4. Second reactor; 5. Outer shell; 6. Inner shell; 7. Carbon rod electrode; 8. DC regulated power supply; 9. Guide tube; 10. Mesh ring plate; 11. Titanium wire; 12. Signal generator; 13. First liquid inlet; 14. Second liquid inlet; 15. First hydrogen inlet; 16. Second hydrogen inlet; 17. First liquid outlet; 18. Second liquid outlet; 19. First pipeline; 20. Second pipeline; 21. Clean water tank; 22. First branch; 23. Second branch; 24. Wastewater tank; 25. Feed pump; 26. Peristaltic pump; 27. First electrically controlled valve; 28. Circulation pump; 29. ​​Second electrically controlled valve; 30. Third electrically controlled valve; 31. Fourth electrically controlled valve. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0039] Example 1

[0040] A biofilm reactor for wastewater treatment systems and hydrogen production includes an ascending bed 1 and a descending bed 3. The outlet end of the ascending bed 1 is connected to the descending bed 3 via a downwardly inclined first reactor 2, and the outlet end of the descending bed 3 is connected to the ascending bed 1 via an upwardly inclined second reactor 4, forming a circulation loop with the flow direction sequentially ascending bed 1, first reactor 2, descending bed 3, and second reactor 4.

[0041] The ascending bed 1 and descending bed 3 have the same structure. The ascending bed 1 includes an outer shell 5 and an inner shell 6. One end of the inner shell 6 is fixedly connected to the inner wall of the outer shell 5. A carbon rod electrode 7 is arranged at the center of the inner shell 6. A carbon rod electrode 7 penetrates the outer shell 5 and is connected to a DC regulated power supply 8. The space between the carbon rod electrode 7 and the inner shell 6 is filled with 180mm nano-sized magnetite particles. The inner shell 6 has a mesh structure, forming a cavity between the outer shell 5 and the inner shell 6. Several evenly spaced guide tubes 9 are arranged within the cavity, with several perforated ring plates 10 in the middle section of each guide tube 9. Hydrogen-producing biofilm particles are filled within the guide tubes 9. Some magnetite particles adhere to the surface of the carbon rod electrode 7, helping to enhance its electrochemical activity; others can enter the cavity through the mesh structure of the inner shell 6. Water flow disturbance promotes extracellular electron transfer (EET) and interspecies electron transfer (IET) of the electroactive bacteria. The DC regulated power supply 8 is connected via a titanium wire 11 (… The circulating pump 28 is electrically connected to the carbon rod electrode 7 to apply an external voltage. The carbon rod electrode 7 serves as both the anode and cathode, and the circulating loop forms an electrolytic cell. The external voltage of the DC regulated power supply 8 is 0.9V. Both the circulating pump 28 and the feed pump 25 are connected to a signal generator 12. The signal generator 12 is used to monitor the terminal fluidization velocity of the circulating loop, which is 1.2Ut.

[0042] The bottom of the ascending bed 1 is provided with a first liquid inlet 13, and the bottom side wall of the descending bed 3 is provided with a second liquid inlet 14. The first liquid inlet 13 and the second liquid inlet 14 are respectively connected to the guide pipe 9. The top of the ascending bed 1 is provided with a first hydrogen port 15, and the top of the descending bed 3 is provided with a second hydrogen port 16. The first hydrogen port 15 and the second hydrogen port 16 are respectively connected to the cavity. The top side wall of the descending bed 3 is provided with a first liquid outlet 17, and a second liquid outlet 18 is provided below the first liquid outlet 17. The second liquid outlet 18 is connected to the first liquid inlet 13 through a first pipe 19. The first liquid outlet 17 is connected to a clean water tank 21 through a second pipe 20. A first branch 22 and a second branch 23 are sequentially provided on the first pipe 19. The first branch 22 is connected to a wastewater tank 24 and a feed pump 25. The second branch 23 is connected to the second liquid inlet 14.

[0043] The first hydrogen port 15 and the second hydrogen port 16 are respectively connected to the peristaltic pump 26. The first pipeline 19 is sequentially equipped with the first electrically controlled valve 27, the circulation pump 28 and the second electrically controlled valve 29. The inlet end of the second branch 23 is located between the circulation pump 28 and the second electrically controlled valve 29. The first branch 22 is equipped with the third electrically controlled valve 30 and the second branch 23 is equipped with the fourth electrically controlled valve 31.

[0044] Both the first reactor 2 and the second reactor 4 are cylindrical structures. The first reactor 2 and the second reactor 4 have the same volume, and the length of the first reactor 2 is less than the length of the second reactor 4.

[0045] The preparation of hydrogen-producing biofilm particles is specifically as follows:

[0046] S1. Transfer PA6 particles to a high-pressure reactor, heat to 120~150℃ and 15~20MPa under nitrogen atmosphere, maintain pressure for 30~60min, and then rapidly depressurize at a depressurization rate of 5~30MPa / s to obtain modified PA6 particles.

[0047] S2. The bacteria were activated and cultured using Escherichia coli strains. After the bacteria were revived, they were transferred to the modified PA6 particles obtained in S1 for pre-culture to obtain carrier particles loaded with mature biofilms and bacterial suspension.

[0048] The specific usage method includes the following steps:

[0049] T1. Transfer the hydrogen-producing biofilm particles into the guide tube 9, and then transfer the carbon rod electrode 7 and magnetite particles into the inner shell 6 in sequence. Purge the reactor system with nitrogen for 15 minutes, seal it, and establish an anaerobic environment.

[0050] T2. Start the feed pump 25 to inject the sewage in the sewage tank 24 into the riser bed 1 until the sewage occupies 95% of the circulation loop volume, then turn off the feed pump 25.

[0051] T3. Start the peristaltic pump 26 and the circulation pump 28, open the first electrically controlled valve 27, the fourth electrically controlled valve 31 and the signal generator 12, and close the second electrically controlled valve 29 and the third electrically controlled valve 30. The circulation pump 28 provides power for the liquid circulation in the circulation loop, allowing the liquid to reciprocate and circulate inside the anaerobic circulating fluidized bed, forming a stable flow state. This allows the wastewater and the products from the electrolysis reaction process to flow through the first pipe 19 along a preset path (entering the circulation loop with the flow direction sequentially from the rising bed 1, the first reactor 2, the falling bed 3 and the second reactor 4. At the same time, in the rising bed 1 and the falling bed 3, in addition to the flow direction within the guide pipe 9 synchronized with the circulation loop, there is also a flow direction of wastewater within the guide pipe 9 along the mesh ring plate 10 to the outside of the guide pipe 9. In addition, there is gas disturbance, causing the wastewater outside the guide pipe 9 to flow into the guide pipe 9). In addition, the peristaltic pump 26 is used to control the gas delivery. After the reaction starts, the hydrogen generated during the flow process floats upward and is collected by the peristaltic pump 26, the first hydrogen port 15 or the second hydrogen port 16 and delivered to the subsequent purification stage. The signal generator 12 monitors the terminal fluidization velocity of the circulation loop, and the obtained monitoring signal is used by the monitoring computer to obtain the rotation speed of the circulation pump 28 and the flow rate of the first electrically controlled valve 27 and the fourth electrically controlled valve 31.

[0052] T4. Record the applied voltage data using a monitoring computer, and use a water quality tester to test the water quality of the sewage in the first pipe 19. When the concentration of organic matter in the sewage meets the discharge standards, close the first electric control valve 27 and the fourth electric control valve 31, open the first outlet 17, and discharge the treated sewage into the clean water tank 21. After the sewage is discharged, close the first outlet 17, and continue to replenish the first inlet 13 with new sewage from the sewage tank 24 and the feed pump 25 to complete one cycle of sewage replacement.

[0053] Example 2

[0054] Based on Example 1, in this example, a biofilm reactor for wastewater treatment system and hydrogen production is provided with a volume of 15L, an ascending bed 1 with an inner diameter of 12cm and a height of 150cm, a first reactor 2 with an inner diameter of 6cm and a length of 53cm, a descending bed 3 with an inner diameter of 12cm and a height of 150cm, a second reactor 4 with an inner diameter of 5cm and a length of 76cm, and a guide pipe 9 with an inner diameter of 4cm.

[0055] Test

[0056] Hydrogen production performance was tested using the equipment from Example 2. A synthetic wastewater system with a glucose concentration of 2.5 g / L as the matrix was used, and approximately 1.0 kg of carrier particles were added. A bacterial suspension (30% v / v) was introduced into the guide tube 9. External voltages of 0, 0.3, 0.6, 0.9, and 1.2 V were applied between the two electrodes, resulting in terminal fluidization velocities (Ut) of 1.1, 1.2, and 1.3 Ut, and particle circulation rates (Gs) of 0.320, 0.415, and 0.510 kg / (m³). 2 ·s), forming a cross-operating condition.

[0057] Before the experiment, the reactor system was purged with nitrogen for 15 minutes to create an anaerobic environment. The temperature was maintained at 23±1℃. Then, the system was switched to continuous mode, using synthetic wastewater containing 2.5 g / L glucose for fermentation, with a hydraulic retention time set to 4 hours. The pH was adjusted to 6.5±0.1. Glucose-containing synthetic wastewater was added every two days.

[0058] The test results are as follows:

[0059] (1) Glucose conversion rate

[0060] like Figure 4 As shown, different applied voltages significantly regulate the glucose conversion rate (Gc) under various fluidization conditions: when the applied voltage increases from 0V to 1.2V, the glucose conversion rate first increases and then decreases under different fluidization conditions. The system reaches its optimal performance at 0.9V, where the peak glucose conversion rate reaches 96.04% when the fluidization velocity is coupled with the particle circulation rate of 0.5 × 10⁻⁶ Gs, an increase of 32.6% compared to the 0V condition (e.g., only 72.3% at 1.2Vt-0.5 × 10⁻⁶ Gs). This phenomenon indicates that 0.9V is the equilibrium point between electrochemical driving and biological metabolism, at which point the anodic oxidation reaction (C₆H₂O) reaches its optimal value. 12 O6→6CO2+24H + +24e - ) and cathode hydrogen production (2H + +2e - →H2) Highly efficient synergy. When the voltage is below 0.9V, the electric field-driven carrier migration can accelerate the metabolic activity of electroactive microorganisms; however, when the voltage exceeds 0.9V, the excessively strong oxidative environment may lead to an imbalance in the microbial membrane potential, thereby inhibiting enzyme activity.

[0061] At a constant voltage, the glucose conversion rate increased by an average of 7.26% as the flow rate increased from 1.1 Ut to 1.2 Ut. This is attributed to the turbulence effect caused by the increased fluidization velocity, which effectively promoted the contact efficiency between glucose and E. coli, thereby accelerating the glucose conversion rate. When the flow rate exceeded 1.2 Ut, the glucose conversion rate showed a negative correlation with the fluidization velocity. Excessively high fluidization velocities can trigger violent collisions between particles, leading to particle aggregation and uneven distribution of reactants, while also causing imbalance in the liquid-solid two-phase mixing and inhibiting the effective retention of particle biomass.

[0062] (2) Hydrogen content

[0063] like Figure 5 As shown, with the increase of applied voltage, the H2 content generated under various fluidization conditions first increases and then decreases. The system achieves optimal hydrogen content at an applied voltage of 0.9V. Specifically, under the condition of 1.2Ut - 0.510-Gs, the hydrogen content reaches a peak of 48.04%, an increase of 22.02% compared to 39.37% under the same fluidization condition at 0V. Further increasing the voltage reduces the improvement in H2 content. This performance improvement indicates that applying a suitable voltage promotes more efficient microbial activity and electrochemical reactions at the cathode. Applying a voltage of 0.9V provides a more favorable balance between energy input and reaction kinetics, thereby optimizing the hydrogen evolution process.

[0064] Under constant voltage, with increasing fluidization velocity, H2 content generally shows a trend of first increasing and then decreasing, but the overall fluctuation range is small, and it is positively correlated with glucose conversion rate. Appropriate fluidization velocity can enhance the metabolic activity and proliferation rate of *E. coli* cells by improving mass transfer efficiency, while also promoting substrate migration and degradation within the biofilm, thus promoting metabolic activity and electron generation. However, when the fluidization velocity exceeds the biofilm's mechanical stability threshold, fluid shear force will damage the biofilm structure, causing *E. coli* loss and reducing metabolic function, directly weakening electron transport capacity.

[0065] (3) Hydrogen production rate

[0066] like Figure 6 As shown, when the applied voltage reaches 0.9V and the fluidization rate increases to 1.2Ut, the system's hydrogen production performance is significantly improved, and the hydrogen production efficiency is positively correlated with Gs. Under the operating conditions of (0.9V, 1.2Ut), the system achieves the maximum hydrogen production rate (HY = 0.484 mol-H2 / mol-glucose) and the peak hydrogen production rate (HPR = 36.17 mL / L·h).

[0067] Therefore, the present invention employs the above-mentioned biofilm reactor for wastewater treatment system and hydrogen production, and optimizes the hydrogen production performance of chemical substances in wastewater by applying external voltage, regulating fluid circulation path and fluidization velocity, thereby simultaneously achieving wastewater purification and long-term stable production of biohydrogen.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A biofilm reactor for wastewater treatment systems and hydrogen production, characterized in that: It includes an ascending bed and a descending bed. The outlet end of the ascending bed is connected to the descending bed through a downwardly inclined first reactor, and the outlet end of the descending bed is connected to the ascending bed through an upwardly inclined second reactor, forming a circulation loop with the flow direction sequentially from the ascending bed, the first reactor, the descending bed, and the second reactor. Both the first reactor and the second reactor are cylindrical structures, with the same volume, and the length of the first reactor is less than the length of the second reactor. The ascending bed and the descending bed have the same structure. The ascending bed includes an outer shell and an inner shell. One end of the inner shell is fixedly connected to the inner wall of the outer shell. A carbon rod electrode is provided at the center of the inner shell. The carbon rod electrode passes through the outer shell and is connected to a DC regulated power supply. Magnetite particles are filled between the carbon rod electrode and the inner shell. A cavity is formed between the outer shell and the inner shell. Several evenly spaced guide tubes are provided in the cavity. Several perforated ring plates are provided in the middle section of the guide tubes. Hydrogen-producing biofilm particles are filled in the guide tubes. The bottom of the ascending bed is provided with a first liquid inlet, and the bottom side wall of the descending bed is provided with a second liquid inlet. The first liquid inlet and the second liquid inlet are respectively connected to the guide pipe. The top of the ascending bed is provided with a first hydrogen port, and the top of the descending bed is provided with a second hydrogen port. The first hydrogen port and the second hydrogen port are respectively connected to the cavity. The top side wall of the descending bed is provided with a first liquid outlet, and a second liquid outlet is provided below the first liquid outlet. The second liquid outlet is connected to the first liquid inlet through a first pipe. The first liquid outlet is connected to a clean water tank through the second pipe. A first branch and a second branch are arranged in sequence on the first pipe. The first branch is connected to a sewage tank and a feed pump. The second branch is connected to the second liquid inlet. The DC regulated power supply is electrically connected to the carbon rod electrode via a titanium wire to apply an external voltage. The carbon rod electrode serves as the anode and cathode, respectively. The circulation loop forms an electrolytic cell. The applied voltage of the DC regulated power supply is 0~1.2V.

2. A biofilm reactor for wastewater treatment systems and hydrogen production according to claim 1, characterized in that: The first hydrogen port and the second hydrogen port are respectively connected to peristaltic pumps. The first pipeline is sequentially equipped with a first electrically controlled valve, a circulation pump and a second electrically controlled valve. The inlet end of the second branch is located between the circulation pump and the second electrically controlled valve. The first branch is equipped with a third electrically controlled valve and the second branch is equipped with a fourth electrically controlled valve.

3. A biofilm reactor for wastewater treatment systems and hydrogen production according to claim 1, characterized in that: The applied voltage of the DC regulated power supply is 0.9V.

4. A biofilm reactor for wastewater treatment systems and hydrogen production according to claim 1, characterized in that: The magnetite particles are specifically 180mm nanometer-sized magnetite particles, and the inner shell has a mesh structure.

5. A biofilm reactor for wastewater treatment systems and hydrogen production according to claim 1, characterized in that: The height of the riser bed is 5 to 15 times the inner diameter of the riser bed, and the inner diameter of the riser bed is 3 to 5 times the inner diameter of the guide pipe.

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