Device for removing antimonate and nitrate in water through biological hydrogen-sulfur autotrophy and electrochemistry

Abstract

A device for removing antimonate and nitrate in water through biological hydrogen-sulfur autotrophy in cooperation with electrochemistry comprises a vertical cylindrical reactor, a water inlet is formed in the bottom of the reactor, an overflow port and an exhaust port are formed in the top of the reactor, and a lower cathode plate, an anode plate and an upper cathode plate which are electrically connected to the same power source are sequentially arranged in the reactor from bottom to top. The space between the lower cathode plate and the anode plate is filled with sulfur filler attached with sulfur autotrophic microorganisms and hydrogen autotrophic microorganisms, and the space between the upper cathode plate and the anode plate is filled with carrier filler attached with hydrogen autotrophic microorganisms. According to the device, antimonate and nitrate can be efficiently removed, chemical reagents do not need to be additionally added, and efficient and energy-saving removal of pollutants is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of water treatment, in particular to a device for removing antimonate and nitrate in water by biological hydrogen-sulfur autotrophy and electrochemistry. Background Art

[0002] my country's "Sanitary Standard for Drinking Water" (GB5749-2022) clearly stipulates that the limit of nitrate (in terms of N) in the conventional index is 10 mg / L, and the limit of antimony in the extended index is 5 μg / L. However, the antimony content in the water bodies around the mining areas in my country has reached more than 1000 μg / L, and the nitrate concentration in shallow and deep groundwater in some parts of my country is found to be above 10 mg / L. Therefore, in order to ensure the safety of drinking water for Chinese residents, removing antimonates and nitrates from water bodies is an urgent problem to be solved.

[0003] At present, the commonly used methods for treating antimonates and nitrates in water bodies are physical, chemical and biological methods. Physical methods mainly include distillation, adsorption, membrane separation and ion exchange, while chemical methods include chemical reduction and electrochemical reduction. However, the physical and chemical methods have the disadvantages of poor selectivity, high operating costs and difficult reaction control, which limit their application in the field of water treatment. Biological methods are widely used in the removal of pollutants in water bodies due to their advantages of low operating costs, high removal efficiency and good selectivity.

[0004] According to the different carbon sources required, biological methods can be divided into heterotrophic reduction and autotrophic reduction. Autotrophic denitrification is more widely used in the removal of pollutants such as nitrates due to its safety, reliability, easy operation, and no secondary pollution of organic matter in the effluent. The hydrogen autotrophic biological method uses hydrogen and other electron donors to reduce Sb(V) and nitrates in the water. However, this method also requires further treatment of the reduction product Sb(III), so it is necessary to further remove antimonates and nitrates in the water by combining other treatment methods; and the use of hydrogen is often dangerous and difficult to apply in practice. Utility Model Content

[0005] The utility model aims to provide a device for removing antimonate and nitrate from water by biological hydrogen-sulfur autotrophic synergistic electrochemical method, which can not only efficiently remove the antimonate and nitrate content, but also does not require the addition of additional chemical reagents, thereby achieving efficient and energy-saving removal of pollutants.

[0006] In order to solve the above technical problems, the specific scheme adopted by the utility model is: a device for biological hydrogen-sulfur autotrophic synergistic electrochemical removal of antimonate and nitrate in water, including a vertical cylindrical reactor, a water inlet is provided at the bottom of the reactor, an overflow port and an exhaust port are provided at the top, and a lower cathode plate, an anode plate and an upper cathode plate electrically connected to the same power supply are provided in sequence from bottom to top in the reactor, a sulfur filler for sulfur autotrophic microorganisms and hydrogen autotrophic microorganisms is filled between the lower cathode plate and the anode plate, and a carrier filler for hydrogen autotrophic microorganisms is filled between the upper cathode plate and the anode plate.

[0007] Preferably, the upper cathode plate and the lower cathode plate are porous mesh plates made of any one or more materials selected from nickel, stainless steel, iron, aluminum, copper, graphite, carbon, platinum, titanium, ruthenium, palladium, and iridium.

[0008] Preferably, the anode plate is a porous mesh plate made of any one or both of iron and aluminum.

[0009] A first porous partition is arranged above the upper cathode plate in the reactor, and a carrier filler to which hydrogen autotrophic microorganisms are attached is filled between the first porous partition and the upper cathode plate.

[0010] The height between the first porous separator and the upper cathode plate is 1 / 8 to 1 / 5 of the height between the upper cathode plate and the anode plate.

[0011] Preferably, a second porous partition is provided at the bottom of the reactor and below the lower cathode plate.

[0012] Preferably, the power supply is a direct current power supply.

[0013] Preferably, the lower cathode plate, the anode plate and the upper cathode plate are all distributed in the horizontal direction.

[0014] Preferably, the cross section of the reactor is circular, the lower cathode plate, the anode plate and the upper cathode plate are all rectangular, and the diameters of the lower cathode plate, the anode plate and the upper cathode plate correspond to the inner diameter of the reactor.

[0015] Preferably, the overflow port is arranged on the side wall at the top of the reactor, and the exhaust port is arranged on the upper edge of the reactor.

[0016] The utility model can utilize microorganisms to autotrophically reduce Sb(V) to Sb(III) and NO3 - Reduced to NO2 - Finally, it is reduced to N2. At the same time, the OH generated by the electrolysis of water can be used -It combines with Sb(III) to form Sb(OH)3 precipitate, and forms co-precipitation with electrocoagulants (Fe(OH)3, etc.), further precipitating and removing Sb(III), thereby achieving efficient removal of antimonates and nitrates in the water body, and then giving full play to the respective advantages of electrochemistry and microorganisms, effectively improving the removal efficiency, and fully simplifying the existing biological treatment unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of Example 1 of the device for biological hydrogen-sulfur autotrophic synergistic electrochemical removal of antimonate and nitrate in water of the utility model;

[0018] Figure 2 This is a schematic structural diagram of Example 2 of the device for biological hydrogen-sulfur autotrophic synergistic electrochemical removal of antimonate and nitrate in water of the utility model;

[0019] Markings in the figure: 1. water inlet, 2. second porous partition, 3. sulfur filler, 4. carrier filler, 5. lower cathode plate, 6. anode plate, 7. upper cathode plate, 8. overflow port, 9. power supply, 10. exhaust port, 11. reactor, 12. first porous partition. DETAILED DESCRIPTION

[0020] The technical solution of the utility model is described below through two embodiments:

[0021] Example 1

[0022] like Figure 1 As shown, the biological hydrogen-sulfur autotrophic synergistic electrochemical removal of antimonate and nitrate from water of this embodiment has a main structure of a cylindrical reactor 11 arranged vertically, a water inlet 1 is provided at the bottom of the reactor 11, and an overflow port 8 is provided on the side wall of the top, and the water body passes through the reactor 11 from bottom to top and overflows and is discharged after the antimonate and nitrate are removed. At the same time, an exhaust port 10 is also provided on the upper edge of the top of the reactor 11 for the discharge of gases generated during the treatment process.

[0023] The reactor 11 is provided with a lower cathode plate 5, an anode plate 6 and an upper cathode plate 7 connected to the same DC power supply 9 from bottom to top. The diameters of the lower cathode plate 5, the anode plate 6 and the upper cathode plate 7 are all corresponding to the inner diameter of the reactor 11, and are arranged in the horizontal direction so that the water passes through the lower cathode plate 5, the anode plate 6 and the upper cathode plate 7 in sequence during the upward flow and reacts. In this embodiment, the lower cathode plate 5 and the upper cathode plate 7 are both porous mesh plates made of stainless steel, while the anode plate 6 is a porous mesh plate made of iron. Through the arrangement of the above plates, an upper chamber mainly composed of sulfur autotrophy and hydrogen autotrophy synergistic reactions is formed between the lower cathode plate 5 and the anode plate 6 in the reactor 11, and is filled with sulfur filler 3 for sulfur autotrophic microorganisms and hydrogen autotrophic microorganisms to attach; a lower chamber mainly composed of hydrogen autotrophic reactions is formed between the anode plate 6 and the upper cathode plate 7 in the reactor 11, and is filled with MBBR as a carrier filler 4 for hydrogen autotrophic microorganisms to attach. A second porous partition plate 2 is also provided below the lower cathode plate 5 in the reactor 11 for blocking impurities such as detached fillers and microorganisms.

[0024] The reaction principle used in this embodiment to remove nitrate and antimonate is as follows:

[0025] The water flows from bottom to top and after entering the upper chamber, NO3 - Finally, it is reduced to N2(NO3 - →NO2 - →N2), Sb(V) is reduced to Sb(III) (Sb(V)→Sb(III)), and S 2- The Sb2S3 precipitate (S 0 +H2O→S 2- +SO4 2- +H + ,Sb(OH)3+S 2- →Sb2S 3 +OH - ), while the hydrogen produced by electrolysis of the lower cathode plate 5 is the reduction process (NO3 - →NO2 - →N2, Sb(V)→Sb(III)) provides electron donor; residual NO3 - After Sb(V) and other intermediate products enter the upper reaction chamber, the hydrogen produced by electrolysis is used for the reduction process (NO3 - →NO2 -→N2, Sb(V)→Sb(III)) provides an electron donor. At the same time, the iron ion flocculant produced by electrolysis of the anode plate 6 can also remove part of the antimonate and nitrate. Finally, the water passes through the upper cathode plate 7 and is discharged through the overflow port 8. In the above reaction process, electroflocculation produces hydroxide ions on the one hand and provides iron ions on the other hand, but Sb(V) will only be removed by iron salt coagulation at pH 4.5-5.5, and Sb(III) is more easily removed by iron salt coagulation. At the same time, the iron hydroxide produced can be used as a coprecipitation carrier to efficiently remove suspended particles in the system. Hydrogen autotrophic and sulfur autotrophic processes will produce trivalent antimony, and Sb(III) is more easily removed by iron salt coagulation. Therefore, this embodiment fully overcomes the defects of electrochemical flocculation, microbial hydrogen autotrophic and other processes, and makes full use of the advantages between the two to complement each other, forming a mode of removing antimonate and nitrate without secondary pollution, simple operation, and easy engineering.

[0026] In addition, this embodiment adopts a continuous water inlet and outlet mode, and the water flows from bottom to top, fully contacts and reacts with the electron donor and the electro-flocculant. Autotrophic microorganisms are used to remove pollutants, and no additional organic carbon source or inorganic electron donor is required, thus avoiding the problem of secondary pollution caused by the addition of organic carbon sources. Based on the efficient removal performance of the upper and lower reaction chambers, this method does not require the increase of reflux, and the effluent can meet the national emission standards. When the operation of the reactor 11 is not ideal, the entire reactor 11 cavity can be properly flushed or backwashed to remove the flocs or microorganisms that block the plates, so as to facilitate the subsequent mass transfer process.

[0027] Two specific implementation cases of this embodiment are as follows:

[0028] Implementation Case 1: Wastewater containing 10 mg / L antimonate and 20 mg-N / L nitrate is transported to the reaction system, and the operating conditions of the reactor 11 are: hydraulic retention time = 8 h, current intensity = 10 mA. Under this condition, the removal rates of antimonate and nitrate can reach 88.05% and 90.57% respectively, the inlet pH value is 7.3, and the outlet pH value is 7.68.

[0029] Implementation Case 2: Wastewater containing 10 mg / L antimonate and 20 mg-N / L nitrate is transported to the reaction system, and the operating conditions of the reactor 11 are: hydraulic retention time = 8 h, current intensity = 20 mA. Under this condition, the removal rates of antimonate and nitrate can reach 91.05% and 95.48% respectively, the inlet pH value is 7.4, and the outlet pH value is 7.71.

[0030] The hydraulic retention time is the average residence time of the experimental water in the bioreactor chamber.

[0031] Example 2

[0032] like Figure 2 As shown, the structure of this embodiment is basically the same as that of embodiment 1, except that in this embodiment, a certain amount of carrier filler 4 is provided above the upper cathode plate 7 for hydrogen autotrophic microorganisms to attach to, and a first porous partition 12 is fixedly provided on the top of the carrier filler 4 to block it from floating. The height of the carrier filler 4 above the upper cathode plate 7 is about 1 / 6 of the height of the carrier filler 4 below the upper cathode plate 7.

[0033] Therefore, the hydrogen obtained by the cathode reaction during the electrolysis process is mainly concentrated on both sides of the cathode plate, and the hydrogen is bound to float upward due to the buoyancy in the water body. Therefore, compared with Example 1, the hydrogen autotrophic microorganisms above the upper cathode plate 7 can use the hydrogen generated by the electrolysis of the upper cathode plate 7 to reduce the pollutants in this embodiment, thereby avoiding the problem that the hydrogen generated on the upper side of the upper cathode plate 7 directly escapes and cannot be fully utilized.

Claims

1. A device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method, characterized in that: The invention comprises a vertical cylindrical reactor (11), wherein a water inlet (1) is arranged at the bottom of the reactor (11), an overflow port (8) and an exhaust port (10) are arranged at the top, and a lower cathode plate (5), an anode plate (6) and an upper cathode plate (7) electrically connected to the same power source (9) are arranged in sequence from bottom to top in the reactor (11), a sulfur filler (3) is filled between the lower cathode plate (5) and the anode plate (6), and a carrier filler (4) is filled between the upper cathode plate (7) and the anode plate (6).

2. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 1, characterized in that: The upper cathode plate (7) and the lower cathode plate (5) are both porous mesh plates made of any one of nickel, stainless steel, iron, aluminum, copper, graphite, carbon, platinum, titanium, ruthenium, palladium, and iridium.

3. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 1, characterized in that: The anode plate (6) is a porous mesh plate made of either iron or aluminum.

4. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 1, characterized in that: A porous partition (2) is provided at the bottom of the reactor (11) and below the lower cathode plate (5).

5. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 1, characterized in that: The power source (9) is a direct current power source (9).

6. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 1, characterized in that: The lower cathode plate (5), the anode plate (6) and the upper cathode plate (7) are all distributed in the horizontal direction.

7. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 6, characterized in that: The cross section of the reactor (11) is circular, the lower cathode plate (5), the anode plate (6) and the upper cathode plate (7) are all rectangular, and the diameters of the lower cathode plate (5), the anode plate (6) and the upper cathode plate (7) correspond to the inner diameter of the reactor.

8. The device for removing antimonate and nitrate by microbial hydrogen-sulfur synergistic electrochemical method according to claim 1, characterized in that: The overflow port (8) is arranged on the side wall at the top of the reactor (11), and the exhaust port (10) is arranged on the upper edge of the reactor (11).

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