Electroactive aerated biofilm reactor for denitrification and phosphorus removal and application thereof

Abstract

The application discloses a kind of electric active aeration biological membrane reactor denitrification phosphorus removal device and application thereof.Electric active aeration biological membrane reactor denitrification phosphorus removal device includes reactor shell and metal anode and MABR composite membrane cathode arranged in the interior of reactor shell;Metal anode is iron material;MABR composite membrane cathode is fixed carbon felt on both sides of flat plate type aeration membrane combination;Metal anode and MABR composite membrane cathode are connected with power supply by external circuit;Flat plate type aeration membrane upper gas port is connected with aeration unit.The electric active aeration biological membrane reactor denitrification phosphorus removal device of the application does not need additional carbon source and reagent, can reduce system additional carbon source amount, strengthen denitrification phosphorus removal efficiency, achieve the purpose of pollution reduction and carbon reduction, with the advantages of low energy consumption, small footprint etc..

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a denitrification and phosphorus removal device of an electroactive aerated biofilm reactor and application thereof. BACKGROUND

[0002] There is an urgent need to develop efficient and low-energy denitrification and phosphorus removal technology.

[0003] Membrane Aerated Biofilm Reactor (MABR) is a new type of sewage treatment process combining gas separation membrane technology and biofilm method sewage treatment technology. This process uses MABR as a microbial carrier and provides bubble-free aeration for microorganisms, forming an aerobic, anoxic and anaerobic biological environment from the membrane layer to the far membrane layer, achieving the effect of simultaneous denitrification and carbon removal. Compared with traditional aeration process, it has the advantages of low energy consumption, non-falling of biofilm and high oxygen utilization rate. However, the nitrogen removal efficiency of MABR under carbon limitation is very limited, and the problem of residual phosphorus in sewage still exists.

[0004] In recent years, research based on electroactive biofilm has gradually become one of the research hotspots in the environmental field, mainly used in wastewater treatment and energy recovery. By introducing electrodes into the biological reactor, external electron acceptors or donors can be provided for microorganisms, enhancing new metabolic processes such as Feammox and NDFO, thereby reducing the addition of additional carbon sources in water and reducing resource waste and capital investment.

[0005] The patent specification with publication number CN114671514A discloses a sewage electrochemical denitrification and phosphorus removal device and method based on electrical conductivity intelligent discrimination. The device includes an AO biochemical reaction system, an electrochemical enhanced denitrification and phosphorus removal system, an electrical conductivity intelligent discrimination system, and a solar power supply device. The main body of the AO biochemical reaction system is a water inlet adjustment tank, an anoxic tank, an aerobic tank, and a water outlet sedimentation tank. The main body of the electrochemical enhanced denitrification and phosphorus removal system is a active metal anode plate, a carbon-based material cathode net, and a direct current power supply. The main body of the electrical conductivity intelligent discrimination system is an electrical conductivity electrode, an electrical conductivity online monitor, and a PLC controller. The PLC controller controls the operation mode of the AO biochemical reaction system and the electrochemical enhanced denitrification and phosphorus removal system according to the electrical conductivity data. The solar power supply device provides auxiliary power.

[0006] The patent specification with publication number CN116253425A discloses a wastewater treatment device based on a bioelectrochemical principle and an operation method, the device comprising an integrated bioelectrochemical reaction tank, a pair of carbon felt anode and cathode connected to a direct current power source are arranged in the reaction tank. The bioelectrochemical reaction tank is filled with polyurethane sponge and polyethylene hollow ball for microbial biofilm formation. Trivalent iron is regularly added to the reaction tank, iron-reducing bacteria are used to realize iron ammonia oxidation, denitrifying bacteria are used to realize denitrification, and ferrous salt produced by iron-reducing bacteria is used to realize simultaneous phosphorus removal.

[0007] Current research has gradually deepened from laboratory scale to the exploration stage of practical application, however, the synergistic mechanism of electrode structure, electric field distribution and biofilm growth is still not perfect, there is a lack of efficient coupling mode of electroactive biofilm and MABR, and the problem of simultaneous removal of nitrogen and phosphorus remains unresolved. SUMMARY

[0008] In view of the above technical problems and the deficiencies in the field, the present application provides an electroactive biological aerated filter reactor denitrification and phosphorus removal device and its application. Compared with traditional denitrification and phosphorus removal devices, the electroactive biological aerated filter reactor denitrification and phosphorus removal device of the present application does not require additional carbon source and chemicals, can reduce the amount of additional carbon source in the system, and can enhance the denitrification and phosphorus removal efficiency, achieving the purpose of simultaneous pollution reduction and carbon reduction, and having the advantages of low energy consumption, small footprint, etc.

[0009] The specific technical solutions are as follows:

[0010] In a first aspect, the present application provides an electroactive biological aerated filter reactor denitrification and phosphorus removal device, comprising a reactor shell and a metal anode and a MABR composite membrane cathode arranged inside the reactor shell; the metal anode is made of iron material; the MABR composite membrane cathode is composed of carbon felt fixed on both sides of a flat plate type aeration membrane; the metal anode and the MABR composite membrane cathode are connected to a power supply through an external circuit; the upper gas port of the flat plate type aeration membrane is connected to an aeration unit. The aeration unit is connected to the MABR composite membrane for oxygen supply.

[0011] The present application combines membrane oxygen supply with electrode electron supply to form a layered conductive biofilm with inner layer nitrification, middle layer denitrification and outer layer iron ammonia oxidation at the MABR composite membrane cathode: nitrifying bacteria oxidize ammonia nitrogen to generate nitrate and / or nitrite, iron ammonia oxidizing bacteria and autotrophic denitrifying bacteria utilize iron anode electrochemical products for ammonia oxidation and nitrogen conversion, and heterotrophic denitrifying bacteria simultaneously convert organic matter and nitrogen. The dissolved iron ions from the anode form a precipitate with phosphate to achieve phosphorus removal.

[0012] Further, the electroactive biological aerated filter reactor denitrification and phosphorus removal device, the reactor shell can be single-chambered.

[0013] In some preferred examples, the electroactive biological aerated filter reactor denitrification and phosphorus removal device, the metal anode is an iron sheet.

[0014] In some preferred embodiments, the distance between the MABR composite membrane cathode and the metal anode in the electroactive aerated biofilm reactor for nitrogen and phosphorus removal is 1 to 50 cm, for example, 5 cm, to enhance electrochemical efficiency and mass transfer effect.

[0015] In some preferred embodiments, the preparation process of the MABR composite membrane cathode in the electroactive aerated biofilm reactor denitrification and phosphorus removal device involves first attaching a flat aeration membrane and then combining it with carbon felt to facilitate the formation of a layered biofilm structure with an inner layer utilizing oxygen and an outer layer conducting electricity.

[0016] In some preferred embodiments, the power source for the electroactive aerated biofilm reactor nitrogen and phosphorus removal device is a DC regulated power supply.

[0017] In some preferred embodiments, the voltage adjustment range of the power supply in the electroactive aerated biofilm reactor nitrogen and phosphorus removal device is 0.1~2.0 V, for example 0.5 V.

[0018] In some preferred embodiments, the power supply of the electroactive aerated biofilm reactor for nitrogen and phosphorus removal is connected to a voltage data acquisition device.

[0019] In some preferred embodiments, the aeration unit of the electroactive aerated biofilm reactor for nitrogen and phosphorus removal is supplied with air by a blower.

[0020] In some preferred embodiments, the electroactive aerated biofilm reactor for nitrogen and phosphorus removal uses a gas flow meter to regulate the air intake in the aeration unit.

[0021] In some preferred embodiments, the electroactive aerated biofilm reactor nitrogen and phosphorus removal device has a pressure gauge installed in the aeration unit to detect the aeration pressure.

[0022] In some preferred embodiments, the aeration pressure of the aeration unit in the electroactive aerated biofilm reactor for nitrogen and phosphorus removal does not exceed 2 MPa, for example, 0.02 MPa.

[0023] In some preferred embodiments, the electroactive aerated biofilm reactor for nitrogen and phosphorus removal has a circulation unit outside the reactor shell. The circulation unit includes a circulating water tank and a circulating pump. The circulation unit can, on the one hand, make the solution inside the reactor shell evenly mixed, for example, by adjusting the circulation flow rate to make the wastewater inside the reactor shell completely mixed. On the other hand, it can store water to regulate the effluent flow rate.

[0024] Secondly, the present invention provides the application of the electroactive aerated biofilm reactor nitrogen and phosphorus removal device described in the first aspect for wastewater treatment. Furthermore, the electroactive aerated biofilm reactor nitrogen and phosphorus removal device can be used to achieve nitrogen and phosphorus removal using electrode electron donors and an internal carbon source under conditions without an external carbon source.

[0025] Thirdly, the present invention provides a wastewater treatment method, which employs the electroactive aerated biofilm reactor nitrogen and phosphorus removal device described in the first aspect.

[0026] The wastewater treatment method includes:

[0027] Wastewater containing organic matter, ammonia nitrogen, and phosphate is fed into the reactor shell. Inside the reactor shell, nitrogen conversion occurs via the MABR composite membrane cathode. A portion of the ammonia nitrogen is oxidized to nitrate and / or nitrite by nitrifying bacteria located in the inner layer of the MABR composite membrane cathode. Iron-ammonia oxidizing bacteria located in the outer layer of the MABR composite membrane cathode use ferric iron converted from electrolysis at the metal anode as a substrate to convert another portion of the ammonia nitrogen into nitrogen gas, nitrate, and / or nitrite. Heterotrophic denitrifying bacteria located in the middle layer of the MABR composite membrane cathode use organic matter for denitrification, while NDFO bacteria use ferrous iron for autotrophic denitrification to remove nitrate and nitrite. Simultaneously, external electrons are conducted through the MABR composite membrane cathode to the external biofilm, accelerating the electron transfer process of iron-ammonia oxidation and NDFO microorganisms, thus improving nitrogen conversion efficiency. Phosphate is mainly removed through coagulation of iron ions around the metal anode, ultimately achieving nitrogen and phosphorus removal from the wastewater.

[0028] Furthermore, the wastewater treatment method may not require an external carbon source. The wastewater treatment method and the electroactive aerated biofilm reactor nitrogen and phosphorus removal device utilize electrode electron donors and internal carbon sources to achieve nitrogen and phosphorus removal.

[0029] Compared with the prior art, the beneficial effects of this invention are as follows:

[0030] (1) This invention combines MABR membrane oxygen supply with electrode power supply to form a layered structure of inner nitrification, middle denitrification and outer iron ammonia oxidation, which promotes the stable coexistence of various microorganisms such as Feammox, NDFO, heterotrophic denitrification.

[0031] (2) The iron ions released during the electrochemical process not only provide substrates for the Feammox and NDFO processes, but also react with phosphates to undergo chemical precipitation reactions, thus achieving simultaneous phosphorus removal.

[0032] (3) The present invention integrates the electrochemical process and the MABR process in the same reactor, which greatly reduces the footprint and reduces the complexity of the process.

[0033] (4) The present invention uses MABR as a biofilm carrier, which can reduce the aeration energy consumption of the nitrification process and reduce the generation of excess sludge, thus having outstanding economic advantages. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of a nitrogen and phosphorus removal device for an electroactive aerated biofilm reactor according to an embodiment of the present invention. In the figure: 1. Water inlet; 2. Reactor shell; 301. Fan; 302. Gas flow meter; 303. Pressure gauge; 401. Metal anode; 402. MABR composite membrane cathode; 5. Power supply; 601. Circulating water storage tank; 602. Circulating pump; 7. Water outlet.

[0036] Figure 2 This is a schematic diagram of the MABR composite membrane cathode structure of this application. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0039] See Figure 1 , Figure 2A nitrogen and phosphorus removal device for an electroactive aerated biofilm reactor includes a reactor shell 2 and a metal anode 401 and a MABR composite membrane cathode 402 disposed inside the reactor shell 2. The bottom of the reactor shell 2 is connected to an inlet water 1. The metal anode 401 is a high-purity iron sheet. The MABR composite membrane cathode 402 is composed of carbon felt fixed on both sides of a flat-plate aeration membrane (hollow fiber membrane). Its preparation process involves first attaching the membrane to the flat-plate aeration membrane and then assembling the carbon felt. The distance between the MABR composite membrane cathode 402 and the metal anode 401 is 1~50 cm. The metal anode 401 and the MABR composite membrane cathode 402 are connected to a power supply 5 via an external circuit. The power supply 5 is a DC regulated power supply with a voltage adjustment range of 0.1~2.0 V, and is connected to a voltage data acquisition device. The upper air inlet of the flat-plate aeration membrane is connected to the aeration unit, which includes a blower 301, a gas flow meter 302, and a pressure gauge 303 connected in sequence. Air is supplied through the blower 301, the gas flow meter 302 regulates the air intake, and the pressure gauge 303 detects the aeration pressure. A circulation unit is installed outside the reactor shell 2. The circulation unit includes a connected circulating water tank 601 and a circulating pump 602. The circulation unit can ensure uniform mixing of the solution inside the reactor shell 2 and can also store water to regulate the flow rate of the effluent 7.

[0040] During wastewater treatment, influent 1 containing pollutants such as COD, ammonia nitrogen, and phosphate flows into the reactor shell 2. Under the action of the circulation unit, the reactor is in a completely mixed state. The aeration unit supplies oxygen to the cathode plate-type aeration membrane through pipelines. Oxygen is transferred to bacteria through the membrane filaments, gradually forming a biofilm. Due to the decrease in oxygen concentration during gas transfer, microorganisms at different distances from the surface of the cathode plate-type aeration membrane exhibit different pollutant removal characteristics, forming a stratified biofilm. In addition, the power source 5 imparts electrical conductivity to the biofilm, thus forming a conductive stratified biofilm. In the electroactive aerated biofilm reactor, C and N pollutants in wastewater first undergo nitrogen conversion in the outer biofilm of the MABR composite membrane cathode 402. Ferrous ammonium oxidizing bacteria in the outer layer utilize ferric iron converted from electrolysis at the metal anode 401 as a substrate to convert ammonia nitrogen into nitrogen gas, nitrate, and / or nitrite. Another portion of the ammonia nitrogen enters the inner biofilm of the MABR composite membrane cathode 402 and is oxidized to nitrate and / or nitrite by nitrifying bacteria. Heterotrophic denitrifying bacteria and NDFO bacteria in the middle layer of the MABR composite membrane cathode 402 denitrify using organic matter and ferrous iron, respectively, removing nitrate, nitrite, and COD. Simultaneously, external electrons are conducted through the MABR composite membrane cathode 402 to the outer biofilm, accelerating the electron transfer process of ferric ammonium oxidation and NDFO microorganisms, thus improving nitrogen conversion efficiency. Phosphate is mainly removed through coagulation of iron ions around the metal anode 401, ultimately achieving nitrogen and phosphorus removal from the wastewater. The purified water is discharged from the effluent into the circulating storage tank 601 for discharge.

[0041] The above-mentioned electroactive aerated biofilm reactor nitrogen and phosphorus removal device will be described in detail below with reference to the embodiments.

[0042] In this embodiment, the reactor shell 2 is made of plexiglass, with dimensions of 15 cm × 15 cm × 12 cm (length × width × height) and an effective volume of 2 L. The reactor shell 2 contains a MABR composite membrane cathode 402 and a metal anode 401. The MABR composite membrane cathode 402 is composed of a flat-plate aeration membrane and carbon felt. The flat-plate aeration membrane is assembled from several 12 cm long composite hollow fiber membranes, with a surface area of ​​0.05 m². 2 The carbon felt measures 12 cm × 10 cm (length × width). After the flat-plate aeration membrane is attached, it is fixed to the surface of the membrane using stainless steel wire. The metal anode 401 is a highly conductive iron sheet, also measuring 12 cm × 10 cm (length × width). The anode and cathode are connected to power supply 5 via an external circuit. The voltage of power supply 5 is adjustable between 0.1 and 2 V. The aeration unit connected to the flat-plate aeration membrane regulates the air supply through gas flow meter 302, with the aeration pressure not exceeding 2 MPa. The circulating water storage tank 601 has a volume of 750 mL.

[0043] The above-mentioned electroactive aerated biofilm reactor was used to treat simulated wastewater containing ammonia nitrogen, phosphate, and COD. The experimental influent settings were as follows: COD: 100 mg / L; NH4Cl: 87.9 mg / L; KH2PO4: 44 mg / L; NaHCO3: 500 mg / L; MgSO4: 200 mg / L; CaCl2: 20 mg / L; trace elements 1 mL / L, with the following composition: ZnSO4·7H2O: 0.12 g / L; MnCl2: 0.5 g / L; CuSO4·5H2O: 0.03 g / L; NiCl2·6H2O: 0.071 g / L; CoCl2·6H2O: 2 g / L; H3BO3: 0.05 g / L; EDTA-2Na: 1.27 g / L.

[0044] Before formal power-on operation, the flat-plate aeration membrane was first cultured to establish a biofilm. A certain amount of sludge taken from the secondary sedimentation tank of a wastewater treatment plant was first inoculated into the reactor shell 2. Then, wastewater containing both ammonia nitrogen and COD was introduced to construct a simultaneous nitrification and denitrification biofilm. The dissolved oxygen concentration in the liquid phase was maintained below 0.5 mg / L by adjusting the gas flow meter 302, and the hydraulic retention time (HRT) was maintained at 12 h. Biofilm establishment was considered complete when the biofilm completely covered the membrane fibers and the effluent ammonia nitrogen concentration was consistently below 10 mg / L; this process generally lasted 20-30 days. Subsequently, the flat-plate aeration membrane was combined with carbon felt and connected to a power source.

[0045] During the formal operation phase, the aeration pressure was set at 0.02 MPa, the regulated DC power supply at 0.5 V, the HRT at 12 h, and the carbon-to-nitrogen ratio at approximately 3. Maintaining other conditions identically, a reactor without an external electric field was set up as a blank control group to measure the system's operational efficiency. The results showed that the electroactive aerated biofilm reactor for nitrogen and phosphorus removal had highly efficient C, N, and P removal capabilities, with an average COD removal rate exceeding 90%, resulting in effluent COD below 10 mg / L; the average ammonia nitrogen and total phosphorus removal rates were greater than 80%, with effluent ammonia nitrogen below 6 mg / L and total phosphorus below 2 mg / L. In contrast, the blank control group had an ammonia nitrogen removal rate below 70% and a total phosphorus removal rate below 30%.

[0046] Furthermore, microbial community structure analysis of the MABR composite membrane cathode biofilm revealed bacteria genera with iron-ammonia oxidation function. Dechloromonas Both autotrophic denitrification and denitrification belong to Defluviimonas , Rhodobacter These bacteria can enhance autotrophic processes within the biofilm, improving pollutant removal efficiency under nutrient-poor conditions. Employing MABR (Maintenance-Based Bioreactor) bubble-free aeration technology significantly reduces aeration energy consumption. Simultaneously, the electric field optimizes the stratified biofilm structure on the MABR, allowing nitrification, iron-ammonia oxidation, and co-culture denitrification to occur in the same space, effectively achieving synergistic pollution and carbon reduction. Compared to conventional activated sludge nitrification / denitrification processes, this process saves approximately 55.2% of energy consumption and at least 55.2% of carbon emissions (excluding the external carbon source from heterotrophic denitrification).

[0047] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A nitrogen and phosphorus removal device for an electroactive aerated biofilm reactor, characterized in that, It includes a reactor shell and a metal anode and a MABR composite membrane cathode disposed inside the reactor shell; the metal anode is made of iron; the MABR composite membrane cathode is composed of carbon felt fixed on both sides of a flat aeration membrane; the metal anode and the MABR composite membrane cathode are connected to a power supply via an external circuit; the air inlet at the top of the flat aeration membrane is connected to the aeration unit.

2. The electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to claim 1, characterized in that, The distance between the MABR composite membrane cathode and the metal anode is 1~50 cm; The metal anode is an iron sheet.

3. The electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to claim 1, characterized in that, The preparation process of MABR composite membrane cathode involves first attaching a flat aeration membrane and then combining it with carbon felt.

4. The electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to claim 1, characterized in that, The power supply is a DC regulated power supply with a voltage adjustment range of 0.1~2.0 V, and the power supply is connected to a voltage data acquisition unit.

5. The electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to claim 1, characterized in that, The aeration unit is supplied with air by a blower, the air intake is regulated by a gas flow meter, and a pressure gauge is set to detect the aeration pressure, which does not exceed 2 MPa.

6. The electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to claim 1, characterized in that, A circulation unit is installed outside the reactor shell. The circulation unit includes a circulating water tank and a circulating pump. The circulation unit can make the solution inside the reactor shell mix evenly on the one hand, and store water to regulate the outflow rate on the other hand.

7. The application of the electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to any one of claims 1 to 6 in wastewater treatment.

8. The application according to claim 7, characterized in that, The electroactive aerated biofilm reactor nitrogen and phosphorus removal device is used to achieve nitrogen and phosphorus removal by utilizing electrode electron donors and internal carbon sources under conditions without external carbon source.

9. A wastewater treatment method, characterized in that, The electroactive aerated biofilm reactor nitrogen and phosphorus removal device according to any one of claims 1 to 6; The wastewater treatment method includes: Wastewater containing organic matter, ammonia nitrogen, and phosphate is fed into the reactor shell. Inside the reactor shell, nitrogen conversion occurs via the MABR composite membrane cathode. A portion of the ammonia nitrogen is oxidized to nitrate and / or nitrite by nitrifying bacteria located in the inner layer of the MABR composite membrane cathode. Iron-ammonia oxidizing bacteria located in the outer layer of the MABR composite membrane cathode use ferric iron converted from electrolysis at the metal anode as a substrate to convert another portion of the ammonia nitrogen into nitrogen gas, nitrate, and / or nitrite. Heterotrophic denitrifying bacteria located in the middle layer of the MABR composite membrane cathode use organic matter for denitrification, while NDFO bacteria use ferrous iron for autotrophic denitrification to remove nitrate and nitrite. Simultaneously, external electrons are conducted through the MABR composite membrane cathode to the external biofilm, accelerating the electron transfer process of iron-ammonia oxidation and NDFO microorganisms, thus improving nitrogen conversion efficiency. Phosphate is mainly removed through coagulation of iron ions around the metal anode, ultimately achieving nitrogen and phosphorus removal from the wastewater.

10. The wastewater treatment method according to claim 9, characterized in that, The wastewater treatment method does not use an external carbon source. The wastewater treatment method and the electroactive aerated biofilm reactor nitrogen and phosphorus removal device utilize electrode electron donors and internal carbon sources to achieve nitrogen and phosphorus removal.

Images