Device for removing total nitrogen in wastewater by electric field activation of pyrite

Abstract

The utility model relates to a kind of electric field activation pyrite removal wastewater total nitrogen device, belong to sewage treatment technical field, the utility model includes water distribution tank, reaction tank and effluent tank;Anode cage, cathode tube are equipped in the reaction tank, and sulphur iron ore particles are filled between cathode tube and anode cage;The power supply is connected to the cathode tube and anode cage;Water distribution tank and reaction tank between being equipped with baffle A, and the bottom of baffle A remains water flow passage A;Reaction tank and effluent tank between being equipped with baffle B;Water flow passage B is left in the left side of baffle B;The structure of the utility model makes sewage contact with sulphur iron ore under the action of electric field, and nitrate nitrogen and nitrite nitrogen can be reduced to nitrogen without biological bacteria, and nitrogen removal rate is high.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology, specifically, it relates to an electric field activated pyrite device for removing total nitrogen from wastewater. Background Technology

[0002] Nitrogen is one of the most significant pollutants in wastewater. The current state of nitrogen pollution in wastewater is mainly characterized by excessive total nitrogen, leading to eutrophication, decreased dissolved oxygen, and threats to aquatic life. Nitrogen in wastewater primarily includes organic nitrogen, ammonia nitrogen, nitrate nitrogen, and nitrite nitrogen. Organic nitrogen includes substances such as proteins and urea, while ammonia nitrogen is expressed in the form of NH3 and NH4+. + Nitrate nitrogen (NO3) exists in the form of nitrogen. - ) and nitrite nitrogen (NO2) - ) are intermediate and final products of the oxidation of nitrogen-containing compounds.

[0003] Traditional wastewater denitrification employs biological denitrification, which utilizes the synergistic action of nitrifying and denitrifying bacteria to nitrate nitrogen. However, these bacteria have stringent requirements regarding environmental conditions such as temperature, pH, and dissolved oxygen; even minor changes can affect their activity, leading to a decrease in denitrification efficiency. Furthermore, toxic and harmful substances in wastewater can also inhibit microbial growth, impacting the effectiveness of biological denitrification.

[0004] Furthermore, biological denitrification has limited efficiency. When there are high requirements for total nitrogen discharge in wastewater, traditional biological denitrification processes alone are insufficient to achieve deep denitrification. Removing low concentrations of ammonia nitrogen and nitrate nitrogen is particularly difficult, leading to excessive total nitrogen levels in the effluent. Most nitrogen-containing wastewater requires the addition of large amounts of nitrogen sources and reagents to achieve good denitrification results, increasing treatment costs. Moreover, some highly efficient denitrification processes, such as membrane bioreactors and aerated biological filters, have high equipment investment and operation and maintenance costs.

[0005] Furthermore, biological denitrification processes generate a large amount of excess sludge, and the treatment and disposal of this sludge is a challenging problem. The dewatering, transportation, landfilling, or incineration of sludge all require significant resources and funds, and improper handling can potentially cause secondary pollution. Summary of the Invention

[0006] To overcome the problems existing in the background technology, this utility model provides an electric field activated pyrite device for removing total nitrogen from wastewater. By setting up an anode cage and a cathode tube, and filling the space between the anode cage and the cathode tube with pyrite particles, the wastewater comes into contact with the pyrite under the action of an electric field. This reduces nitrate nitrogen and nitrite nitrogen to nitrogen gas without the need for biological bacteria. The Fe in the pyrite... 2+ S 2- and S 0This invention synergistically reduces nitrate and nitrite nitrogen to nitrogen gas, eliminating the need for biological denitrification and thus overcoming the problem of harsh reaction conditions associated with biological denitrification.

[0007] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0008] The electric field activated pyrite removal device for removing total nitrogen from wastewater includes a water distribution tank, a reaction tank, and an effluent tank; the reaction tank is equipped with an anode cage and a cathode tube, and pyrite particles are filled between the cathode tube and the anode cage; the cathode tube and the anode cage are connected to a power source.

[0009] Preferably, a partition A is provided between the water distribution tank and the reaction tank, and a water flow channel A is provided at the bottom of the partition A; a partition B is provided between the reaction tank and the water outlet tank; a water flow channel B is provided on the left side of the partition B.

[0010] Preferably, the anode cage is a cylindrical tube with rhomboid mesh, and the cathode is tubular. The anode cage and the cathode tube are arranged concentrically, and pyrite particles are filled between the anode cage and the cathode tube to form a pyrite filler layer.

[0011] Preferably, the cylindrical tube of the anode cage is provided with a limiting plate that passes through the cathode tube and can slide up and down along the cathode tube; the limiting plate is positioned above the pyrite packing layer.

[0012] Preferably, the electric field activated pyrite wastewater total nitrogen removal device further includes a backwashing system; the backwashing system includes an air fan, an air backwash pipe, a backwash pump, and a backwash water pipe; the outlet ends of the air backwash pipe and the backwash water pipe are connected to the upper end of the cathode tube through a tee pipe; the inlet end of the air backwash pipe is connected to the air fan; the inlet end of the backwash water pipe is connected to the backwash pump; and the side wall of the cathode tube is provided with a vent hole.

[0013] Preferably, the anode cage and cathode tube are arranged in pairs, and multiple pairs are arranged in an array and fixed in the reaction tank.

[0014] Preferably, the reaction tank is equipped with baffles.

[0015] Preferably, the power supply is a DC pulse power supply.

[0016] Preferably, the anode cage is made of titanium substrate with Ti4O7 catalyst layer and the cathode tube is made of stainless steel; the pyrite particles have a particle size of 1-5 mm.

[0017] Preferably, the anode cage is provided with an anode terminal and the cathode tube is provided with a cathode terminal, and the anode terminal and the cathode terminal are respectively connected to the power supply through wires.

[0018] The beneficial effects of this utility model are:

[0019] This invention's structure allows wastewater to contact pyrite under an electric field. Through electrochemical reduction, the electric field provides electrons, directly or indirectly reducing nitrate and nitrite nitrogen to nitrogen gas. The Fe in the pyrite... 2+ S 2- and S 0 This invention synergistically reduces nitrate and nitrite nitrogen into nitrogen gas. Simultaneously, pyrite can form a galvanic cell with Fe as the anode and S as the cathode, enabling micro-electrolysis within a small area. This strengthens electron transfer and transmission, promotes the reduction reaction, and accelerates the process of reducing nitrate and nitrite nitrogen into nitrogen gas. Therefore, this invention can achieve deep removal of nitrogen from wastewater.

[0020] Compared to existing biological denitrification devices, this invention overcomes the problem of stringent reaction conditions associated with biological denitrification because it eliminates the need for biological bacteria. Furthermore, it achieves more thorough nitrogen removal, lower costs, and significantly reduced sludge production.

[0021] This invention features a limiting plate that slides up and down along the cathode tube inside the cylindrical tube of the anode cage. When used in conjunction with a backwashing system, the limiting plate does not affect the rise of the pyrite packing layer during backwashing, while simultaneously blocking the pyrite and preventing it from overflowing from the anode cage. Attached Figure Description

[0022] Figure 1 This is a top view of the device structure of Embodiment 1 of this utility model;

[0023] Figure 2 This is a side view of the device structure of Embodiment 1 of this utility model;

[0024] Figure 3 This is a schematic diagram of the electrode structure of this utility model;

[0025] Figure 4 This is a top view of the device structure of Embodiment 2 of this utility model;

[0026] Figure 5 This is a side view of the device structure of Embodiment 2 of this utility model;

[0027] Note: The dashed lines in the diagram represent the reaction tank area, not the actual structure.

[0028] In the diagram, 1 is the water inlet, 2 is the water distribution tank, 3 is the anode cage, 4 is the cathode tube, 5 is the pyrite particles, 6 is the reaction tank, 7 is the backwash pump, 8 is the backwash water pipe, 9 is the cathode wire, 10 is the anode wire, 11 is the air backwash pipe, 12 is the water outlet tank, 13 is the water outlet pipe, 14 is the air fan, 15 is the DC pulse power supply, 16 is the cathode terminal, 17 is the anode terminal, 18 is the limiting plate, 19 is the guide plate, 20 is the baffle A, and 21 is the baffle B. Detailed Implementation

[0029] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, so as to facilitate the understanding of those skilled in the art.

[0030] In the description of this utility model, unless otherwise stated, the terms "left", "lower", etc., indicate the orientation or state relationship based on the orientation or state relationship shown in the drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "equipped with" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] Example 1

[0033] An apparatus for removing total nitrogen from wastewater by activating pyrite with an electric field includes a water distribution tank 2, a reaction tank 6, and an outlet tank 12. A partition A20 is provided between the water distribution tank 2 and the reaction tank 6, and a water flow channel A is provided at the bottom of the partition A20. A partition B21 is provided between the reaction tank 6 and the outlet tank 12, and a water flow channel B is provided on the left side of the partition B21.

[0034] The reaction tank 6 is equipped with an electrode reaction device; the electrode reaction device includes a cathode tube 4, an anode cage 3, pyrite particles 5, a DC pulse power supply 15, and accessories for fixing the anode cage 3 and the cathode tube 4.

[0035] The anode cage 3 is a cylindrical tube with a rhomboid mesh, and the cathode tube 4 is a straight tube. The anode cage 3 and the cathode tube 4 are fixed concentrically in pairs. Pyrite particles 5 are filled between the anode cage 3 and the cathode tube 4 to form a pyrite filler layer. The cylindrical tube of the anode cage 3 is provided with a limiting plate 18 that passes through the cathode tube 4 and can slide up and down along the cathode tube 4; the limiting plate 18 is located above the pyrite filler layer and can block the pyrite particles 5.

[0036] Each set of anode cages 3 and cathode tubes 4, along with the pyrite particles 5 filled inside them, forms a set of electric field elements; multiple electric field elements are arranged in an array and fixed within the reaction tank 6.

[0037] Each anode cage 3 is equipped with an anode terminal 17, and each cathode tube 4 is equipped with a cathode terminal 16. The anode terminal 17 and cathode terminal 16 are connected to the DC pulse power supply 15 via wires (cathode wire 9 and anode wire 10), respectively. The anode cage 3 and cathode tube 4 are fixed by insulating material fittings installed inside the reaction tank 6. Fixing the cylinder and tubular structure with insulating material is a conventional and mature technology. This embodiment does not limit the fixing method; any structure that can fix the anode cage 3 and cathode tube 4 of this utility model is acceptable.

[0038] The anode cage 3 is made of titanium oxide, and the cathode tube 4 is made of stainless steel; the pyrite particles 5 have a particle size of 1-5mm.

[0039] As a preferred embodiment, the reaction tank 6 is equipped with baffles 19, and a water flow channel is reserved between the baffles 19 and the tank wall of the reaction tank 6. Along the water flow direction, the water flow channel of the first baffle 19 is opened on the right side, and the water flow channel of the second baffle 19 is opened on the left side. By setting baffles 19, the travel and residence time of sewage in the reaction tank 6 are extended, thereby extending the denitrification reaction time.

[0040] The working process and denitrification mechanism of this utility model:

[0041] Wastewater enters the distribution tank through inlet 1 and then flows into reaction tank 6 through water flow channel A of baffle A20. Under the influence of the electric field within reaction tank 6, the wastewater comes into contact with pyrite and undergoes a denitrification reaction. The denitrification reaction mechanism is as follows:

[0042] Pyrite removes total nitrogen through electrochemical reduction under an electric field, utilizing the synergistic chemical reduction of sulfur and iron, and the micro-electrolysis effect. The mechanism involves chemical reduction, electron transfer via the electric field, and the effect of local micro-cells to remove nitrate nitrogen (NO3). - ) and nitrite nitrogen (NO 2- It is reduced to nitrogen gas (N2) and escapes from the water, thereby removing total nitrogen from the wastewater.

[0043] Total nitrogen removal mainly involves the following steps:

[0044] (1) Activation and decomposition of pyrite

[0045] Under the influence of an electric field, pyrite decomposes and releases Fe. 2+ Zero-valent sulfur also participates in reduction as a reducing agent.

[0046] FeS2→Fe 2+ +2S 0 +2e-

[0047] (2)Fe 2+ S 0 It reacts with nitrate nitrogen as an electron donor.

[0048] 3Fe 2+ +NO3 - +4H + →3Fe 3+ +NO↑+2H2O

[0049] Fe 2+ +NO3 - +2H + →Fe 3+ +NO↑+H2O

[0050] 3S 0 +4NO3 - +4H + →3SO4 2- +4NO↑+2H2O

[0051] S 0 +2NO3 - +2H + →SO4 2- +2NO↑+H2O

[0052] 3FeS2+8NO 2- +8H + →3Fe 3+ +6SO4 2- +4N2↑+4H2O

[0053] (3) Nitrate nitrogen and nitrite nitrogen are reduced by electrochemical process to generate nitrogen gas.

[0054] 2NO3 - +12H + +10e-→N2↑+6H2O

[0055] 2NO2-+8H + +6e-→N2↑+4H2O

[0056] (4) Reduction and removal of total nitrogen by micro-electrolysis effect

[0057] The galvanic cell formed by pyrite in pyrite can decompose total nitrogen (including nitrate nitrogen, nitrite nitrogen, etc.) through electrochemical reactions. In the pyrite-iron galvanic cell, FeS2 acts as the negative electrode, undergoing oxidation and losing electrons. Nitrate nitrogen or nitrite nitrogen in the solution gains electrons at the positive electrode and undergoes reduction. Electrons flow from the negative electrode to the positive electrode, forming an electric current, thereby driving the reaction. At the same time, ions in the solution move directionally under the influence of the electric field, maintaining charge balance.

[0058] Negative electrode reaction: FeS2 + 15e- + 8H2O = Fe 3+ +2SO4 2- +16H +

[0059] Positive electrode reaction: 2NO3 - +10e-+12H + =N2↑+6H2O

[0060] 2NO2 - +6e-+8H + =N2↑+4H2O.

[0061] After denitrification, the wastewater enters the outlet tank 12 through the water flow channel B reserved in the partition B21, and is discharged through the outlet pipe 13, thus completing the denitrification process.

[0062] Example 2

[0063] This embodiment adds a backwashing system to the existing embodiment 1. This embodiment mainly describes the backwashing system.

[0064] During the denitrification process, insoluble fine particles are generated between the pyrite particles 5, which block the gaps, prevent electron transfer, and affect the mass transfer effect. In order to flush away these fine particles, a backwashing system is set up.

[0065] The cathode tube 4 has through holes in its wall. The backwashing system includes an air fan 14, an air backwash pipe 11, a backwash pump 7, and a backwash water pipe 8. The outlet ends of the air backwash pipe 11 and the backwash water pipe 8 are connected to the upper end of the cathode tube 4 via a tee pipe; the inlet end of the air backwash pipe 11 is connected to the air fan 14; the inlet end of the backwash water pipe 8 is connected to the backwash pump 7; both the air backwash pipe 11 and the backwash water pipe 8 are made of insulating materials such as plastic, and both are equipped with valves.

[0066] During backwashing: First, stop the water intake from the inlet 1, open the valve on the air backwash pipe 11, and turn on the air blower 14. The backwash air enters each cathode tube 4 through the air backwash pipe 11. Through the through holes opened on the wall of the cathode tube 4, the air loosens the pyrite particles. Then, turn off the air blower 14 and the air backwash pipe 11, open the valve on the backwash water pipe 8, and start the backwash pump 7. The backwash water carries the detached particles out from the pyrite layer along the through holes on the cathode tube 4 and is carried to the outlet tank 12 for discharge with the sewage flow.

[0067] The limiting plate 18 of this utility model has a through hole in the center that can pass through the cathode 4, so that the limiting plate 18 can move up and down along the cathode tube 4. During backwashing, the pyrite particles 5 are blown and expanded by air and water, and the volume of the pyrite packing layer increases. The limiting plate 18 will move upward along the cathode tube 4, which will not block the expansion of the pyrite packing layer, and at the same time prevent the pyrite from being blown into the sewage and lost.

[0068] Application Example 1:

[0069] A chemical production wastewater has a total nitrogen concentration of 20 mg / L. The pH is adjusted to 4. The wastewater is continuously added to the distribution tank 22 through inlet 1. A DC pulse power supply is turned on, with pyrite particles of 5 mm in diameter and a current density of 20 mA / cm³. 2 After a continuous reaction of 30 minutes, the TN concentration in the effluent was measured to be 5.6 mg / L.

[0070] Application Example 2:

[0071] The wastewater was treated under the same conditions as in Application Example 1. The current density was increased to 40 mA / cm2 and the reaction was continued for 30 min. The TN concentration in the effluent was 2.3 mg / L. It can be seen that increasing the electric field strength increases the electron transfer rate and shortens the reaction time.

[0072] Pyrite is inexpensive and readily available; an electric field can enhance reaction efficiency, avoiding the nitrogen source requirements of traditional denitrification, and producing Fe. 3+ Insoluble matter and elemental sulfur residues require periodic backwashing to restore.

[0073] This invention is applicable to the treatment of nitrate pollution in industrial wastewater (such as mining wastewater and chemical wastewater), and is especially suitable for wastewater with a low C / N ratio.

[0074] Pyrite can effectively remove total nitrogen under the action of an electric field through electrochemical reduction, iron-sulfur synergy and micro-electrolysis. Its mechanism is based on chemical reduction and electron transfer, with fast reaction speed and high removal efficiency.

[0075] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of this utility model.

Claims

1. A device for removing total nitrogen from wastewater by electric field-activated pyrite, characterized in that: It includes a water distribution tank, a reaction tank, and an outlet tank; the reaction tank is equipped with an anode cage and a cathode tube, and pyrite particles are filled between the cathode tube and the anode cage; the cathode tube and the anode cage are connected to a power source.

2. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 1, characterized in that: A partition A is provided between the water distribution tank and the reaction tank, and a water flow channel A is provided at the bottom of the partition A; a partition B is provided between the reaction tank and the water outlet tank; a water flow channel B is provided on the left side of the partition B.

3. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 1, characterized in that: The anode cage is a cylindrical tube with rhomboid mesh, and the cathode is tubular. The anode cage and cathode tube are arranged concentrically, and pyrite particles are filled between the anode cage and the cathode tube to form a pyrite filler layer.

4. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 3, characterized in that: The cylindrical tube of the anode cage is equipped with a limiting plate that passes through the cathode tube and can slide up and down along the cathode tube; the limiting plate is positioned above the pyrite packing layer.

5. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 3 or 4, characterized in that: It also includes a backwashing system; the backwashing system includes an air fan, an air backwash pipe, a backwash pump, and a backwash water pipe; the outlet ends of the air backwash pipe and the backwash water pipe are connected to the upper end of the cathode tube through a T-junction; the inlet end of the air backwash pipe is connected to the air fan; the inlet end of the backwash water pipe is connected to the backwash pump; and the side wall of the cathode tube is provided with a vent hole.

6. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 3 or 4, characterized in that: The anode cage and cathode tube are arranged in pairs, and multiple pairs are arranged in an array and fixed in the reaction tank.

7. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 6, characterized in that: The reaction tank is equipped with baffles.

8. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 1, characterized in that: The power supply is a DC pulse power supply.

9. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 1, characterized in that: The anode cage is made of titanium substrate with Ti4O7 catalyst layer and stainless steel cathode tube; the pyrite particles have a particle size of 1-5 mm.

10. The electric field activated pyrite removal device for total nitrogen removal from wastewater according to claim 1, characterized in that: The anode cage is equipped with an anode terminal, and the cathode tube is equipped with a cathode terminal. The anode terminal and the cathode terminal are respectively connected to the power supply through wires.

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