Wastewater denitrification process utilizing divalent manganese ion autotrophic denitrification

Abstract

The invention provides a wastewater nitrogen removal process utilizing divalent manganese ion autotrophic denitrification, and relates to the technical field of sewage treatment. The wastewater denitrification process utilizing divalent manganese ion autotrophic denitrification comprises the following steps: impregnating and loading divalent manganese on the surface of a polyurethane sponge filler to obtain a divalent manganese loaded polyurethane sponge filler; the method comprises the following steps: carrying out microbial enrichment culture on activated sludge by using a divalent manganese-loaded polyurethane sponge filler to obtain domesticated activated sludge; and carrying out autotrophic denitrification treatment on the wastewater to be treated by utilizing the domesticated activated sludge to realize wastewater denitrification. According to the denitrification method, no additional organic carbon source is needed, and the risk that COD exceeds the standard is avoided; manganese oxide generated by oxidizing divalent manganese ions has a special crystal structure and surface properties, has a special electron transfer characteristic, and can effectively promote the electron transfer efficiency in the denitrification process, so that the denitrification efficiency is improved, and the accumulation of N2O is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly to a wastewater denitrification process using autotrophic denitrification with divalent manganese ions. Background Art

[0005] Research shows that one of the largest anthropogenic sources of N2O emissions is sewage treatment plants. N2O from biological processes accounts for approximately 80% of the carbon footprint of sewage treatment plants. One of the inevitable intermediate products in the denitrification process is N2O, and the greenhouse effect exhibited by nitrous oxide (N2O) is 296 times that of carbon dioxide (CO2). Autotrophic denitrification is a process in which microorganisms, under anoxic conditions, use H2, reduced sulfur compounds, iron, and manganese substrates as electron donors, inorganic carbon as a carbon source, and NO3 - as an electron acceptor to reduce NO3 - to N2 (NO3 - →NO2 - →NO→N2O→N2). The reduction of nitrogen oxides (NO3 - 、NO2 - 、NO、N2O) is controlled by the denitrification enzyme system (Nar, Nir, Nor, Nos). The reason for N2O accumulation is the different electron competition abilities among the various reductases. When the electron flux for nitrite reduction is higher than the electron flux for N2O reduction, N2O accumulation occurs. By controlling the manganese (II) ion concentration and optimizing the electron competition mechanism, the generation of N2O during the denitrification process can be effectively reduced. Currently, no scholars have proposed a method for reducing N2O emissions by coupling manganese oxidation with the denitrification process.

[0006] In recent years, some methods have emerged to achieve autotrophic denitrification and nitrogen removal through process optimization or the adoption of certain technical methods. Specifically: Patent Application ① CN119240987A, a method for treating nitrogen in high-nitrogen wastewater using autotrophic denitrification technology, uses sulfur as an electron donor, and by adjusting the pH value of the wastewater, heating, and controlling the influent flow rate, nitrate nitrogen and nitrite nitrogen in the wastewater can be removed without adding an organic carbon source. The microbial domestication time for this method is relatively long. Patent Application ② CN118702273A, a MnOx -Preparation method of denitrification filler by combining modified slow-release carbon source to strengthen deep denitrification of low C / N sewage, denitrification system and denitrification method. The filler is composed of a slow-release carbon source modified by crushed agricultural waste and manganese oxide. The reactor adopts an upflow biological filter, which can realize heterotrophic-manganese autotrophic denitrification and carbon reduction and denitrification. This method has the disadvantages of high maintenance cost and the risk of secondary pollution. Patent application ③ CN119306320A, a method for synergistic deep treatment of carbon, nitrogen and phosphorus in urban sewage based on biological manganese oxide, inoculates hydrolytic acidification bacteria, denitrifying bacteria, anaerobic ammonium oxidation bacteria and manganese oxidizing bacteria into the denitrification filter, and gradually increases the proportion of secondary influent, realizing the efficient removal of carbon, nitrogen and phosphorus in the secondary effluent of urban sewage. This method has poor shock load resistance and complex operation process.

[0007] The above patents can achieve the purpose of denitrification of wastewater. However, the above solutions have the disadvantages of long microbial domestication time, poor shock load resistance, high maintenance cost, etc., and none of them pay attention to the problem of N2O accumulation in the denitrification process. Summary of the Invention

[0008] The purpose of the present invention is to provide a wastewater denitrification process using divalent manganese ion autotrophic denitrification to solve the problems of long microbial domestication time, poor shock load resistance, high maintenance cost and N2O accumulation existing in the existing wastewater denitrification process.

[0009] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0010] The present invention provides a wastewater denitrification process using divalent manganese ion autotrophic denitrification, including the following steps:

[0011] 1) Mix and soak the polyurethane sponge with sodium hydroxide solution for surface activation; mix the surface-activated polyurethane sponge with a reducing agent and a solution of divalent manganese salt with different concentrations for impregnation loading. After completing the impregnation loading, mix the polyurethane sponge with a surface load of divalent manganese with a solution of a cross-linking agent for cross-linking fixation to obtain a divalent manganese-loaded polyurethane sponge filler.

[0012] 2) Use the divalent manganese-loaded polyurethane sponge filler to enrich and culture the activated sludge for microorganisms to obtain domesticated activated sludge.

[0013] 3) Use the domesticated activated sludge prepared in step 2) to perform autotrophic denitrification treatment on the wastewater to be treated.

[0014] The microorganisms include one or more of Ca.N.manganoxidans, Ca.N.manganoxydans and Ca.N.manganoxidant.

[0015] Preferably, in step 1), the concentration of the sodium hydroxide solution is 1-2 mol / L, the surface activation time is 1-3 h, and the temperature is 50-70 °C;

[0016] The divalent manganese salt includes manganese chloride and / or manganese sulfate; the concentration of the divalent manganese salt solution is 0.2-1 mol / L;

[0017] The reducing agent is ascorbic acid and / or hydroxylamine sulfate, and the mass ratio of the reducing agent to the divalent manganese salt solution is 0.05-0.5:100;

[0018] The impregnation loading time is 3-4 h, and the impregnation loading temperature is 30-40 °C;

[0019] The atmosphere for impregnation loading is an anaerobic atmosphere;

[0020] The crosslinking agent is glutaraldehyde and / or polyethyleneimine, and the mass concentration of the crosslinking agent solution is 8%;

[0021] The crosslinking and fixing temperature is 30-40 °C, and the crosslinking and fixing time is 2-3 h.

[0022] Preferably, the process of microbial enrichment culture in step 2) is as follows:

[0023] Mix the divalent manganese-loaded polyurethane sponge filler with the activated sludge, and then introduce artificial wastewater to gradually domesticate the activated sludge. When the influent NO3 - -N concentration in the artificial wastewater is 50 mg / L and the effluent NO3 - -N removal rate ≥ 90%, the domestication of the activated sludge is completed, and the domesticated activated sludge is obtained;

[0024] Among them, at each gradient, when the effluent NO3 - -N removal rate ≥ 90%, enter the next gradient;

[0025] The concentration of NO3 - -N in the artificial wastewater is 20-50 mg / mL.

[0026] Preferably, when the divalent manganese-loaded polyurethane sponge filler is immersed in water, the release rate of divalent manganese ions is: 3.3-­3.7 mg / (g·d) on the 1st to 6th days, and 1.8-2.2 mg / (g·d) on the 7th to 30th days;

[0027] During the process of microbial enrichment culture, the released divalent manganese and NO3 - -N in the artificial wastewater are controlled to have a molar ratio of 1:1-1.1 by controlling the filling mass of the divalent manganese-loaded polyurethane sponge filler;

[0028] The suspended solid concentration of the activated sludge is 3000-4000 mg / L.

[0029] Preferably, the artificial wastewater comprises components with the following mass concentrations: 0.30 g / L NaNO3, 1.5 g / L NaHCO3, 0.18 g / L Na2HPO4·12H2O, 0.1 g / L MgCl2·6H2O, 0.01 g / L CaCl2, 0.06 mL / L trace element solution;

[0030] The pH value of the artificial wastewater is 6.5-7.0.

[0031] Preferably, the trace element solution contains substances with the following concentrations: 0.25 g / L ZnSO4·7H2O, 0.4 g / L CoCl2·6H2O, 0.35 g / L MnCl2·4H2O, 0.25 g / L CuSO4·5H2O, 0.06 g / L Na2MoO4·2H2O, 0.18 g / L KI, 0.15 g / L H3BO3, 5 g / L FeSO4·2H2O, and 1.5 g / L EDTA.

[0032] Preferably, when the artificial wastewater is domesticated, the influent rate of the artificial wastewater is 1.11-2.22 mL / min, and the residence time for each cycle is 23-47 h.

[0033] Preferably, the - -N removal rate of the effluent is calculated as follows:

[0034]

[0035] where C0 and V0 are the concentration and volume of NO3 - -N entering the reactor in this cycle, respectively; C1 and V1 are the concentration and volume of NO - -N in the reactor at the end of the previous cycle, respectively; C2 and V2 are the concentration and volume of NO - -N in the reactor at the end of this cycle, respectively.

[0036] Preferably, during the microbial enrichment culture in step 2) and the treatment of the wastewater in step 3), the oxygen content in the system is independently DO < 0.5 mg / L, and the temperature is independently 30-35 °C;

[0037] During the autotrophic denitrification treatment of the wastewater to be treated, the release of divalent manganese from the polyurethane sponge filler loaded with divalent manganese is controlled to make the molar ratio of divalent manganese to NO3 - -N in the artificial wastewater 1:1.

[0038] Preferably, the NO3 in the wastewater to be treated in step 3)- The concentration of -N ≤ 50 mg / L, and the concentration of NO3 - -N in the wastewater to be treated after autotrophic denitrification treatment ≤ 5 mg / L;

[0039] During the treatment process, the wastewater is stirred at a stirring rate of 20 - 30 r / min;

[0040] The pH value of the wastewater to be treated is 6.5 - 7.0.

[0041] The present invention has at least the following beneficial effects:

[0042] 1) The denitrification method of the present invention does not require an external organic carbon source, is used for denitrification treatment of sewage with a low C / N ratio, and has a high denitrification efficiency, up to 90% and above. Compared with the continuous flow process commonly used for autotrophic denitrification, the treatment process of the present invention has the advantages of small floor area, simple start-up and shutdown, and short acclimation time.

[0043] 2) The denitrification method of the present invention does not cause an increase in COD and has no risk of COD exceeding the standard; the manganese oxide formed by the oxidation of divalent manganese ions has a special crystal structure and surface properties, has special electron transfer characteristics, can effectively promote the electron transfer efficiency during the denitrification process, and thus improves the denitrification efficiency and reduces the accumulation of N2O.

[0044] 3) The filler used in the present invention has a simple preparation method, a small dosage of medicine, and the filler slowly releases divalent manganese ions, making the system more stable. Description of the Drawings

[0045] Figure 1 It is a schematic diagram of the mechanism of manganese oxidation coupled with denitrification process;

[0046] Figure 2 It is a schematic diagram of the sequencing batch bioreactor device;

[0047] As shown in the figure: 1 - inlet water tank; 2 - WTW monitoring host; 3 - pH probe; 4 - inlet pipe; 5 - inlet water pump; 6 - real-time data system; 7 - circulating outlet pipe; 8 - stirrer; 9 - top cover; 10 - stirring paddle; 11 - outlet pipe; 12 - circulating inlet pipe; 13 - constant temperature water bath; 14 - outlet water tank; 15 - water bath interlayer; 16 - pool body; 17 - outlet water pump; 18 - circulating pump; 19 - nitrate nitrogen monitoring probe; 20 - PLC control system; 21 - computer control system; 22 - microporous aeration disc; 23 - flowmeter; 24 - air pump; 25 - dissolved oxygen monitoring probe; 26 - gas outlet; 27 - gas collection bag. Detailed Embodiments

[0048] The present invention provides a wastewater denitrification process using divalent manganese ion autotrophic denitrification, including the following steps:

[0049] 1) The polyurethane sponge is mixed and soaked with sodium hydroxide solution for surface activation;

[0050] The surface-activated polyurethane sponge is mixed with a reducing agent and a solution of divalent manganese salts with different concentrations for impregnation loading. After the impregnation loading is completed, the polyurethane sponge with divalent manganese loaded on the surface is mixed with a solution of a cross-linking agent for cross-linking fixation to obtain a polyurethane sponge filler loaded with divalent manganese;

[0051] 2) The polyurethane sponge filler loaded with divalent manganese is used for microbial enrichment culture of activated sludge to obtain domesticated activated sludge;

[0052] 3) The domesticated activated sludge prepared in step 2) is used for autotrophic denitrification treatment of the wastewater to be treated;

[0053] The microorganisms include one or more of Ca.N.manganoxidans, Ca.N.manganoxydans, and Ca.N.manganoxidant.

[0054] Figure 1 It is a schematic diagram of the mechanism of the manganese oxidation-coupled denitrification process. The specific principle is as follows: Mn(II) is catalytically oxidized to Mn(IV) by the enzyme secreted by microorganisms outside the cell, and electrons are released during this process; the released electrons can be transferred into the cell for reducing nitrate. Nitrate reductase (Nar) converts NO3 - -N to NO2 - -N, nitrite reductase (Nir) converts NO2 - -N to NO, nitric oxide reductase (Nor) converts NO to N2O, and nitrous oxide reductase (Nos) finally reduces N2O to N2 to complete the conversion of nitrogen. This process involves electron transfer, accompanied by the generation and utilization of energy, providing energy for the life activities of microorganisms, and achieving the synchronous removal of Mn(II) and NO3 - -N in the wastewater.

[0055] In the present invention, in step 1), the concentration of the sodium hydroxide solution is 1-2 mol / L, preferably 1.2-1.8 mol / L, more preferably 1.5 mol / L; the time for surface activation is 1-3 h, preferably 1.5-2.5 h, more preferably 1.76-2.25, and even more preferably 2 h; the temperature is 50-70 °C, preferably 55-65 °C, more preferably 60 °C.

[0056] In the present invention, the divalent manganese salt in step 1) includes manganese chloride and / or manganese sulfate, preferably manganese sulfate; the concentration of the solution of the divalent manganese salt is 0.2 to 1 mol / L, preferably 0.3 to 0.9 mol / L, more preferably 0.4 to 0.8 mol / L, and even more preferably 0.5 to 0.7 mol / L.

[0057] In the present invention, the reducing agent in step 1) is ascorbic acid and / or hydroxylamine sulfate, preferably ascorbic acid; the mass ratio of the reducing agent to the solution of the divalent manganese salt is 0.05 to 0.5:100, preferably 0.1 to 0.45:100, more preferably 0.15 to 0.4:100, and even more preferably 0.2 to 0.3:100.

[0058] In the present invention, the impregnation loading time in step 1) is 3 to 4 h, preferably 3.25 to 3.75 h, more preferably 3.5 h; the impregnation loading temperature is 30 to 40 °C, preferably 33 to 38 °C, more preferably 35 °C.

[0059] In the present invention, the atmosphere for impregnation loading in step 1) is an anaerobic atmosphere.

[0060] In the present invention, the crosslinking agent in step 1) is glutaraldehyde and / or polyethyleneimine, preferably glutaraldehyde; the mass concentration of the solution of the crosslinking agent is 8%.

[0061] In the present invention, the crosslinking and fixing temperature in step 1) is 30 to 40 °C, preferably 33 to 38 °C, more preferably 35 °C; the crosslinking and fixing time is 2 to 3 h, preferably 2.25 to 2.75 h, more preferably 2.5 h.

[0062] In the present invention, the process of microbial enrichment culture in step 2) is as follows:

[0063] Mix the polyurethane sponge filler loaded with divalent manganese with the activated sludge, and then introduce artificial wastewater to gradually domesticate the activated sludge. When the influent NO3 - -N concentration of the artificial wastewater is 50 mg / L and the effluent NO3 - -N removal rate ≥ 90%, the domestication of the activated sludge is completed, and the domesticated activated sludge is obtained;

[0064] Among them, at each gradient, when the effluent NO3 - -N removal rate ≥ 90%, enter the next gradient;

[0065] In the present invention, the concentration of NO3 - -N in the artificial wastewater is 20 to 50 mg / mL.

[0066] In the present invention, the gradient acclimation is preferably carried out by setting artificial wastewater with different NO3 - -N gradient concentrations, and as the acclimation time increases, the concentration of NO3 - -N increases with the gradient.

[0067] In the present invention, when the manganese (II)-loaded polyurethane sponge filler is immersed in water, the release rate of manganese (II) ions is as follows: 3.3 - 3.7 mg / (g·d) from the 1st to the 6th day, and 1.8 - 2.2 mg / (g·d) from the 7th to the 30th day. This parameter is obtained from the actual polyurethane sponge filler.

[0068] During the process of microbial enrichment culture, by controlling the filling mass of the manganese (II)-loaded polyurethane sponge filler, the molar ratio of the released manganese (II) to NO3 - -N in the artificial wastewater is 1:1.1, preferably 1:1.

[0069] In the present invention, the suspended solid concentration of the activated sludge is 3000 - 4000 mg / L, preferably 3100 - 3900 mg / L, further preferably 3200 - 3800 mg / L, and more preferably 3300 - 3700 mg / L.

[0070] In the present invention, the artificial wastewater comprises the following components by mass concentration: 0.30 g / L NaNO3, 1.5 g / L NaHCO3, 0.18 g / L Na2HPO4·12H2O, 0.1 g / L MgCl2·6H2O, 0.01 g / L CaCl2, and 0.06 mL / L trace element solution.

[0071] In the present invention, the manganese (II)-loaded polyurethane sponge filler generates manganese (II) ions during the treatment process. By supplementing the manganese (II)-loaded polyurethane sponge filler, the molar ratio of the generated manganese (II) ions to NO3 - -N in the artificial wastewater is 1.

[0072] In the present invention, the pH value of the artificial wastewater is 6.5 - 7.0.

[0073] In the present invention, the trace element solution contains the following substances by concentration: 0.25 g / L ZnSO4·7H2O, 0.4 g / L CoCl2·6H2O, 0.35 g / L MnCl2·4H2O, 0.25 g / L CuSO4·5H2O, 0.06 g / L Na2MoO4·2H2O, 0.18 g / L KI, 0.15 g / L H3BO3, 5 g / L FeSO4·2H2O, and 1.5 g / L EDTA.

[0074] In the present invention, the residence time of the artificial wastewater in each cycle during domestication is 23 to 47 h, the residence time of the first cycle is 23 to 30 h, the residence time of the second cycle is 30 to 40 h, and the residence time of the third cycle is 40 to 37 h. The residence time increases with the cycle.

[0075] In the present invention, the - calculation method of the effluent NO3

[0076]

[0077] where C0 and V0 are the concentration and volume of NO3 - -N entering the reactor in this cycle respectively; C1 and V1 are the concentration and volume of NO3 - -N in the reactor at the end of the previous cycle respectively; C2 and V2 are the concentration and volume of NO3 - -N in the reactor at the end of this cycle respectively.

[0078] In the present invention, during the process of microbial enrichment culture in step 2) and the treatment of wastewater in step 3), the oxygen content in the system is independently DO < 0.5 mg / L; the temperature is independently 30 to 35 °C, and can be 31 °C, 32 °C, 33 °C, 34 °C or 35 °C, among which 35 °C is the optimal, suitable for the growth and reproduction of microorganisms.

[0079] In the present invention, during the process of autotrophic denitrification treatment of the wastewater to be treated, the release of divalent manganese from the polyurethane sponge filler loaded with divalent manganese is controlled by controlling the filling mass, so that the molar ratio of divalent manganese to NO3[[ID=2—4]] - -N in the artificial wastewater is 1:1

[0080] In the present invention, the concentration of NO3 - -N in the wastewater to be treated in step 3) ≤ 50 mg / L, and the concentration of NO3 - -N in the wastewater to be treated after autotrophic denitrification treatment ≤ 5 mg / L;

[0081] During the treatment process, the wastewater is stirred, and the stirring rate is 20 to 30 r / min, preferably 22 to 28 r / min, and further preferably 25 r / min. Slow stirring is used to prevent excessive air from entering the water.

[0082] In the present invention, the pH value of the wastewater to be treated is 6.5 to 7.0.

[0083] In the present invention, the wastewater denitrification process using divalent manganese ions for autotrophic denitrification is preferably carried out in a sequencing batch reactor device.

[0084] The schematic diagram of the sequencing batch reactor device is as Figure 2As shown in the figure, it includes a water inlet tank 1; a WTW monitoring host 2; a pH probe 3; a water inlet pipe 4; a water inlet pump 5; a real-time data system 6; a circulating outlet pipe 7; a stirrer 8; a top cover 9; a stirring paddle 10; an outlet pipe 11; a circulating inlet pipe 12; a constant temperature water bath 13; a water outlet tank 14; a water bath interlayer 15; a tank body 16; a water outlet pump 17; a circulating pump 18; a nitrate nitrogen monitoring probe 19; a PLC control system 20; a computer control system 21; a microporous aeration disc 22; a flow meter 23; an air pump 24; a dissolved oxygen monitoring probe 25; an air outlet 26; and a gas collecting bag 27.

[0085] Among them, the water inlet tank 1 is connected to the tank body 16 through the water inlet pipe 4 and the water inlet pump 5. The tank body is connected to the water outlet tank 14 through the outlet pipe 11 and the water outlet pump 17. Inside the tank body 16, there are a stirring paddle 10, a nitrate nitrogen monitoring probe 19, a microporous aeration disc 22, and a dissolved oxygen monitoring probe 25. Inside the water inlet tank 1, there is a pH probe 3. The air flow rate of the microporous aeration disc is controlled by the air pump 24 and the flow meter 23. Outside the tank body 16, there is a water bath interlayer and it is connected to the constant temperature water bath 13 through the circulating pump 18 and the circulating inlet pipe 12.

[0086] The pH probe 3 and the dissolved oxygen monitoring probe 25 are connected to the WTW monitoring host 2, and the nitrate nitrogen monitoring probe 19 is connected to the real-time data system 6. Moreover, the WTW monitoring host 2 and the real-time data system 6 are connected to the computer control system 21 through the PLC control system 20, to real-time monitor the pH of the influent water, the dissolved oxygen (DO), and the concentration of nitrate nitrogen (NO3 - -N) in the tank body 16. And the computer control system 21 also controls the water inlet pump 5 and the water outlet pump 17 through the PLC control system 20.

[0087] The divalent manganese-loaded polyurethane sponge filler is filled in the tank body 16.

[0088] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0089] Embodiment 1

[0090] 1) Immerse the polyurethane sponge in ethanol and ultrasonically clean it for 30 minutes to remove surface impurities, then dry it at 60 °C for later use. Then immerse it in 1 mol / L NaOH solution and soak it at 60 °C for 2 hours for surface activation. Then rinse it repeatedly with deionized water until neutral and dry it for later use. Immerse the polyurethane sponge in manganese sulfate solution and impregnate and load it under vacuum gradient for 3 times. The concentration gradient of the manganese sulfate solution is 1 - 0.5 - 0.2 mol / L, and the manganese sulfate solution with the gradient concentration also contains ascorbic acid with a mass concentration of 1%. Immerse the impregnated and loaded polyurethane sponge in 8% glutaraldehyde solution for 3 h for cross-linking and fixing. Finally, dry it under vacuum at 60 °C for 24 hours to obtain the sponge filler loaded with divalent manganese. During the above processes of surface activation, impregnation and loading, and cross-linking and fixing, the solution should cover the polyurethane sponge.

[0091] 2) The loading amount of divalent manganese on the surface of the sponge filler loaded with divalent manganese is 100 mg / g, and the release rate of manganese is 3.5 mg / (g·d) within 1 - 6 days and 2 mg / (g·d) within 7 - 30 days. Control the molar ratio of the released amount of manganese to the content of NO3 - -N in the sewage to be 1:1. Supplement the filler according to the content of NO3 - -N in the wastewater to be treated. First, fill 5.7 g of the polyurethane sponge filler loaded with divalent manganese into the tank body 16 of the sequencing batch reactor as Figure 2 shown (the effective volume is 5 L, the diameter is 18 cm, and the height is 25 cm), and then add 3 L of activated sludge from the secondary sedimentation tank of the sewage treatment plant (the suspended solid concentration is 3500 mg / L).

[0092] Prepare artificial wastewater containing different concentrations of nitrate nitrogen (NO3 - -N), where the concentration gradient of NO3 - -N is 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, and the pH value is 6.7 ± 0.1. In addition, the artificial wastewater also contains the following components with the following mass concentrations: 0.30 g / L NaNO3, 1.5 g / L NaHCO3, 0.18 g / L Na2HPO4·12H2O, 0.1 g / L MgCl2·6H2O, 0.01 g / L CaCl2, 0.06 mL / L trace element solution. The trace element solution contains the following substances with the following concentrations: 0.25 g / L ZnSO4·7H2O, 0.4 g / L CoCl2·6H2O, 0.35 g / L MnCl2·4H2O, 0.25 g / L CuSO4·5H2O, 0.06 g / L Na2MoO4·2H2O, 0.18 g / L KI, 0.15 g / L H3BO3, 5 g / L FeSO4·2H2O, and 1.5 g / L EDTA.

[0093] 3) The artificial wastewater with a nitrate nitrogen (NO3 - -N) concentration of 20 mg / L was introduced into the pool body 16 at a rate of 1.1 mL / min through the water inlet pipe 4. The stirring paddle 10 was stirred at a rate of 20 r / min, and nitrogen gas was introduced into the system through the microporous aeration disk to keep the DO in the water body < 0.5 mg / L (the hydraulic retention time was 24 h, including 15 h of water inlet, 24 h of stirring, 50 min of sedimentation, and 10 min of water outlet). After 3 months, the removal rate of NO3 - -N in the effluent reached 90% stably, and the first-stage domestication was completed.

[0094] 4) The operations in step 3) were repeated successively using artificial wastewater with nitrate nitrogen (NO3 - -N) concentrations of 30 mg / L, 40 mg / L, and 50 mg / L respectively to domesticate the sludge in the pool body 16. The filling amounts of the polyurethane sponge filler loaded with divalent manganese corresponding to the sewage at the above concentrations were 7.9 g, 10.5 g, and 13.2 g respectively. When the influent NO3 - -N concentration reached 50 mg / L and the removal rate of NO3 - -N in the effluent reached 90% stably, the domestication was completed. The microbial community structure was determined by high-throughput sequencing technology, including three dominant bacteria: Ca.N.manganoxidans, Ca.N.manganoxydans, and Ca.N.manganoxidant.

[0095] 5) The domesticated sludge was used to treat the primary-treated domestic wastewater in the sewage treatment plant. The water quality of the domestic wastewater is shown in Table 1.

[0096] 8.6 g of the sponge filler loaded with divalent manganese was added to the pool body 16 to maintain a molar ratio of 1:1 between the manganese release amount during the treatment process and the content of NO3 - -N in the sewage. Then, after adjusting the pH value of the domestic wastewater to 6.7 ± 0.1, it was introduced into the bottom of the pool body 16 at a flow rate of 3.7 mL / min. The hydraulic retention time was 15 h, including 9 h of water inlet, 15 h of stirring, 50 min of sedimentation, and 10 min of water outlet. The temperature in the pool body 16 was controlled at 35 °C by the constant temperature water bath 13. After the treatment was completed, the supernatant was pumped into the water outlet tank 14, and the water in the water outlet tank was immediately sampled and filtered with a 5 mL syringe. After detection, the nitrate nitrogen in the effluent was 3 mg / L, and the removal rate was 90%; the N2O accumulation amount was 0.001 mg N / L.

[0097] Table 1 Water quality indicators of the primary-treated domestic wastewater in the sewage treatment plant

[0098] Water quality index <![CDATA[Nitrate nitrogen (mg·L -1 )]]> <![CDATA[COD (mg·L -1 )]]> PH Value 30 40 8.0

[0099] Example 2

[0100] Steps 1) to 4) are the same as those in Example 1

[0101] 5) Treat the industrial wastewater with the acclimated sludge. The water quality of the industrial wastewater is shown in Table 2

[0102] Add 14.3 g of sponge filler loaded with divalent manganese to the tank body 16 to maintain the molar ratio of the manganese release amount to the content of NO3 - -N in the sewage at 1:1. Then dilute the industrial wastewater first and adjust the pH value to 6.7 ± 0.1, and then introduce it into the bottom of the tank body 16 from the bottom at a flow rate of 2.2 mL / min. The hydraulic retention time is 24 h, including 15 h of water inlet, 24 h of stirring, 50 min of sedimentation, and 10 min of water outlet. The temperature in the tank body 16 is controlled at 35 °C by the constant temperature water bath 13. After the treatment is completed, pump the supernatant into the water outlet tank 14, and immediately sample and filter the water in the water outlet tank with a 5 mL syringe. After detection, the nitrate nitrogen in the effluent is 5 mg / L, and the removal rate is 90%; the N2O accumulation amount is 0.001 mg N / L

[0103] Table 2 Water quality indicators of the industrial wastewater before and after dilution

[0104] Water quality index <![CDATA[Nitrate nitrogen (mg·L -1 )]]> <![CDATA[COD (mg·L -1 )]]> PH Value 2000 600 7.0 After dilution 50 15 /

[0105] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention

Claims

1. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification, characterized in that, It includes the following steps: 1) Mix and soak the polyurethane sponge with sodium hydroxide solution for surface activation; mix the surface-activated polyurethane sponge with a reducing agent and a solution of divalent manganese salts with different concentrations for impregnation loading. After completing the impregnation loading, mix the polyurethane sponge with a surface load of divalent manganese with a cross-linking agent solution for cross-linking fixation to obtain a divalent manganese-loaded polyurethane sponge filler; 2) Use the divalent manganese-loaded polyurethane sponge filler to perform microbial enrichment culture on the activated sludge to obtain domesticated activated sludge; 3) Use the domesticated activated sludge prepared in step 2) to perform autotrophic denitrification treatment on the wastewater to be treated to complete the wastewater denitrification process; The microorganisms include one or more of Ca.N.manganoxidans, Ca.N.manganoxydans, and Ca.N.manganoxidant.

2. The wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 1, characterized in that In step 1), the concentration of the sodium hydroxide solution is 1-2 mol / L, the surface activation time is 1-3 h, and the temperature is 50-70 °C; The divalent manganese salts include manganese chloride and / or manganese sulfate; the concentration of the divalent manganese salt solution is 0.2-1 mol / L; The reducing agent is ascorbic acid and / or hydroxylamine sulfate, and the mass ratio of the reducing agent to the divalent manganese salt solution is 0.05-0.5:100; The impregnation loading time is 3-4 h, and the impregnation loading temperature is 30-40 °C; The cross-linking agent is glutaraldehyde and / or polyethyleneimine, and the mass concentration of the cross-linking agent solution is 8%; The cross-linking fixation temperature is 30-40 °C, and the cross-linking fixation time is 2-3 h.

3. The wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 2, characterized in that, In step 2), the process of microbial enrichment culture is as follows: Mix the polyurethane sponge filler loaded with divalent manganese with the activated sludge, and then introduce artificial wastewater to gradually domesticate the activated sludge. When the influent NO3 - -N concentration of the artificial wastewater is 50 mg / L and the effluent NO3 - -N removal rate ≥ 90%, the domestication of the activated sludge is completed, and the domesticated activated sludge is obtained; Among them, at each gradient, when the NO3 - -N removal rate is ≥ 90%, proceed to the next gradient; The concentration of NO3 - -N in the artificial wastewater is 20 - 50 mg / mL.

4. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 3, characterized in that, When the divalent manganese-loaded polyurethane sponge filler is immersed in water, the release rate of divalent manganese ions is: 3.3-3.7 mg / (g·d) on the 1st-6th day, and 1.8-2.2 mg / (g·d) on the 7th-30th day; During the process of microbial enrichment culture, the released divalent manganese and NO3 in the artificial wastewater are controlled by controlling the filling mass of the polyurethane sponge filler loaded with divalent manganese - -N have a molar ratio of 1:1 to 1.1; The suspended solid concentration of the activated sludge is 3000-4000 mg / L.

5. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 4, characterized in that, The artificial wastewater includes the following components by mass concentration: 0.30 g / L NaNO3, 1.5 g / L NaHCO3, 0.18 g / L Na2HPO4·12H2O, 0.1 g / L MgCl2·6H2O, 0.01 g / L CaCl2, 0.06 mL / L trace element solution; The pH value of the artificial wastewater is 6.5-7.

0.

6. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 5, characterized in that, The trace element solution contains the following substances by concentration: 0.25 g / L ZnSO4·7H2O, 0.4 g / L CoCl2·6H2O, 0.35 g / L MnCl2·4H2O, 0.25 g / L CuSO4·5H2O, 0.06 g / L Na2MoO4·2H2O, 0.18 g / L KI, 0.15 g / L H3BO3, 5 g / L FeSO4·2H2O, and 1.5 g / L EDTA.

7. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to any one of claims 3 to 6, characterized in that, When domesticating the artificial wastewater, the influent rate of the artificial wastewater is 1.11-2.22 mL / min, and the residence time for each cycle is 23-47 h.

8. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 7, characterized in that, The effluent NO3 - -N removal rate is calculated as follows: Among them, C0 and V0 are the NO3 - -N concentration and volume entering the reactor in this cycle respectively; C1 and V1 are the NO3 - -N concentration and volume in the reactor at the end of the previous cycle respectively; C2 and V2 are the NO3 - -N concentration and volume in the reactor at the end of this cycle respectively.

9. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 8, characterized in that, During the microbial enrichment culture in step 2) and the treatment of the wastewater in step 3), the dissolved oxygen (DO) content in the system is independently ≤ 0.5 mg / L, and the temperature is independently 30 - 35 °C; During the process of autotrophic denitrification treatment of the wastewater to be treated, the molar ratio of divalent manganese released from the polyurethane sponge filler loaded with divalent manganese to NO3 - -N in the artificial wastewater is controlled to be 1:1 by controlling the filling mass of the polyurethane sponge filler loaded with divalent manganese.

10. A wastewater denitrification process using divalent manganese ions for autotrophic denitrification according to claim 9, characterized in that, The concentration of NO3 - -N in the wastewater to be treated described in step 3) ≤ 50 mg / L, and the concentration of NO3 - -N in the wastewater to be treated after autotrophic denitrification treatment ≤ 5 mg / L; During the treatment process, the wastewater is stirred, and the stirring rate is independently 20 - 30 r / min; The pH value of the wastewater to be treated is 6.5 - 7.0.

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