A wastewater denitrification process using divalent manganese ion autotrophic denitrification

Abstract

The application provides a wastewater denitrification process using divalent manganese ion autotrophic denitrification, and relates to the technical field of sewage treatment. The wastewater denitrification process using divalent manganese ion autotrophic denitrification comprises the following steps: impregnating polyurethane sponge filler with loaded divalent manganese on the surface to obtain polyurethane sponge filler loaded with divalent manganese; using the polyurethane sponge filler loaded with divalent manganese to carry out microbial enrichment culture on activated sludge to obtain domesticated activated sludge; using the domesticated activated sludge to carry out autotrophic denitrification treatment on wastewater to be treated to realize wastewater denitrification. The denitrification method does not need additional organic carbon source, and has no risk of exceeding the standard of COD; manganese oxide generated by oxidation of divalent manganese ions has special crystal structure and surface properties, and has special electron transfer characteristics, which can effectively promote the electron transfer efficiency in the denitrification process, thereby improving the denitrification efficiency and reducing the accumulation of N2O.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions. Background Technology

[0002] With the rapid development of industry and agriculture, the large-scale discharge of industrial and domestic wastewater and the extensive use of chemical fertilizers in agricultural systems have led to an increase in nitrate (NO3) levels in water bodies. - Pollution is worsening. Excessive NO 3- Ingestion of NO3 poses a significant threat to aquatic environments and human safety, and can exacerbate eutrophication. Furthermore, cellular ion imbalances, stomach cancer, and blue baby syndrome are all linked to NO3. - It is related to excessive intake.

[0003] Biological denitrification is the removal of NO3. - One of the commonly used methods is heterotrophic denitrification. Currently, heterotrophic denitrification is mainly used; however, due to the low C / N ratio in the aquatic environment, the denitrification efficiency is very limited. Therefore, it is necessary to add organic matter to the wastewater to achieve heterotrophic denitrification. This method has problems such as large sludge production, high operating costs, and the potential for secondary pollution. Compared with heterotrophic denitrification technology, autotrophic denitrification technology has less environmental pollution and lower biological production. Currently, autotrophic denitrification based on sulfur, hydrogen, and iron is widely used, but research on the application of manganese (II) in wastewater denitrification is limited.

[0004] Manganese is a serious environmental pollutant, and the World Health Organization limits its concentration in drinking water to 0.1 μmg / L. Scholars both domestically and internationally have proposed numerous methods for removing manganese ions from water, including physicochemical methods such as chlorination, ion exchange, and membrane filtration. However, these methods have not been widely adopted due to the high cost of equipment and the potential for secondary pollution. Autotrophic denitrification based on manganese can remove manganese(II) and NO3. - The simultaneous removal of [something] is currently being studied primarily in continuous flow reactors, which has drawbacks such as long cultivation time, poor resistance to shock loads, and high maintenance costs.

[0005] Studies have shown that one of the largest anthropogenic sources of N2O emissions is wastewater treatment plants. N2O from biological processes accounts for approximately 80% of the carbon footprint of wastewater treatment plants. N2O is an inevitable intermediate product of denitrification, and its greenhouse effect is 296 times that of carbon dioxide (CO2). Autotrophic denitrification is a process in which microorganisms, under anaerobic conditions, use H2, reduced sulfur compounds, iron, and manganese substrates as electron donors, inorganic carbon as a carbon source, and NO3- as a byproduct. - NO3- acts as an electron acceptor - The process of reducing to N2 (NO3) - →NO2 -→NO→N2O→N2), nitrogen oxides (NO3) - NO2 - The reduction of nitrite (NO and N2O) is controlled by a denitrifying enzyme system (Nar, Nir, Nor, Nos). N2O accumulation occurs because of the different electron competition abilities among the reductases; when the electron flux used for nitrite reduction is higher than that used for N2O reduction, N2O accumulation happens. By controlling the manganese(II) ion concentration and optimizing the electron competition mechanism, N2O production during denitrification can be effectively reduced. Currently, no researchers have proposed a method for N2O emission reduction using manganese oxidation coupled with the denitrification process.

[0006] In recent years, some methods have emerged that achieve autotrophic denitrification nitrogen removal through process optimization or the use of certain technologies. Specifically: Patent application ① CN119240987A describes a method for treating nitrogen in high-nitrogen wastewater using autotrophic denitrification technology. This method uses sulfur as an electron donor and removes nitrate and nitrite nitrogen from the wastewater by adjusting the wastewater pH, heating, and controlling the influent flow rate, without the need for adding organic carbon sources. This method requires a relatively long microbial acclimation period. Patent application ② CN118702273A describes a method for removing MnOx... - A method for preparing modified slow-release carbon source-enhanced deep denitrification packing for low C / N wastewater, a denitrification system, and a denitrification method are presented. The packing is composed of a slow-release carbon source modified from crushed agricultural waste and manganese oxides. The reactor adopts an upflow biological filter, which can achieve heterotrophic-manganese autotrophic denitrification synergistic carbon reduction and denitrification. This method has high maintenance costs and the risk of secondary pollution. Patent application ③ CN119306320A describes a method for synergistic deep treatment of carbon, nitrogen, and phosphorus in urban wastewater based on biological manganese oxides. By inoculating a denitrifying filter with hydrolytic acidifying bacteria, denitrifying bacteria, anaerobic ammonia oxidizing bacteria, and manganese oxidizing bacteria, and gradually increasing the proportion of secondary influent, it achieves efficient removal of carbon, nitrogen, and phosphorus from the secondary effluent of urban wastewater. This method has poor resistance to shock loads and a complex operation process.

[0007] The aforementioned patents can achieve the purpose of denitrification and nitrogen removal in wastewater. However, the above solutions have disadvantages such as long microbial acclimatization time, poor resistance to shock loads, and high maintenance costs, and none of them address the issue of N2O accumulation during the denitrification process. Summary of the Invention

[0008] The purpose of this invention is to provide a wastewater denitrification process that utilizes autotrophic denitrification of divalent manganese ions to solve the problems of long microbial acclimatization time, poor resistance to shock loads, high maintenance costs, and N2O accumulation in existing wastewater denitrification processes.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0010] This invention provides a wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions, comprising the following steps:

[0011] 1) The polyurethane sponge was mixed with sodium hydroxide solution for surface activation; the surface-activated polyurethane sponge was mixed with reducing agent and solutions of divalent manganese salts of different concentrations for impregnation and loading; after impregnation and loading, the polyurethane sponge with divalent manganese loaded on the surface was mixed with a solution of crosslinking agent for crosslinking and fixation, thus obtaining polyurethane sponge filler with divalent manganese loaded on the surface.

[0012] 2) Microbial enrichment culture of activated sludge was carried out using polyurethane sponge packing material loaded with divalent manganese to obtain acclimatized activated sludge.

[0013] 3) Use the acclimated activated sludge obtained 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, the concentration of the sodium hydroxide solution in step 1) 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 solution of the divalent manganese salt 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 to 0.5:100;

[0018] The impregnation time is 3-4 hours, and the impregnation temperature is 30-40°C.

[0019] The atmosphere in which the impregnation load is placed is an oxygen-free atmosphere;

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

[0021] The cross-linking fixation temperature is 30–40°C, and the cross-linking fixation time is 2–3 hours.

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

[0023] Polyurethane sponge packing material loaded with divalent manganese was mixed with activated sludge, and then artificial wastewater was introduced to perform gradient acclimatization of the activated sludge. When the influent NO3 of the artificial wastewater... --N concentration is 50 mg / L, NO3 in effluent - When the -N removal rate is ≥90%, the activated sludge acclimatization is completed, and acclimatized activated sludge is obtained.

[0024] Among them, under each gradient, the effluent NO3 - -When the removal rate of -N is ≥90%, proceed to the next gradient;

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

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

[0027] During the microbial enrichment culture process, the release of divalent manganese and NO3 from the artificial wastewater is controlled by adjusting the filling quality of the polyurethane sponge filler loaded with divalent manganese. - The molar ratio of -N is 1:1 to 1.1;

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

[0029] Preferably, the artificial wastewater comprises the following components at 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, and 0.06 mL / L trace element solution;

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

[0031] Preferably, the trace element solution contains the following concentrations of substances: 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 LEDTA.

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

[0033] Preferably, the effluent NO3 - The method for calculating the -N removal rate is as follows:

[0034]

[0035] Where C0 and V0 are the NO3 entering the reactor in this cycle, respectively. - -N concentration and volume; C1 and V1 are the NO3 concentration and volume in the reactor at the end of the previous cycle, respectively. - -N concentration and volume; C2 and V2 are NO3 in the reactor at the end of this cycle, respectively. - -N concentration and volume.

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

[0037] During the autotrophic denitrification treatment of the wastewater, the release of divalent manganese from the polyurethane sponge filler, which is loaded with divalent manganese, is controlled by adjusting the filling quality of the filler. This control is crucial for the reaction between the released divalent manganese and NO3 in the artificial wastewater. - The molar ratio of -N is 1:1.

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

[0039] The wastewater is stirred during the treatment process at a rate of 20–30 r / min.

[0040] The pH value of the wastewater to be treated is 6.5 to 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 and is used to denitrify wastewater with a low C / N ratio. It has a high denitrification efficiency of up to 90% or more. Compared with the continuous flow process used for general autotrophic denitrification, the treatment process of the present invention has the advantages of small footprint, simple start-up and shutdown, and short acclimatization time.

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

[0044] 3) The packing material used in this invention has a simple preparation method, requires a small dosage, and slowly releases divalent manganese ions, resulting in higher system stability. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the mechanism of manganese oxidation coupled with denitrification.

[0046] Figure 2 This is a schematic diagram of a sequencing batch reactor (SBR) device.

[0047] As shown in the figure: 1-Inlet tank; 2-WTW monitoring host; 3-pH probe; 4-Inlet pipe; 5-Inlet pump; 6-Real-time data system; 7-Circulating outlet pipe; 8-Agitator; 9-Top cover; 10-Agitator paddle; 11-Outlet pipe; 12-Circulating inlet pipe; 13-Constant temperature water bath; 14-Outlet tank; 15-Water bath jacket; 16-Tank body; 17-Outlet pump; 18-Circulating pump; 19-Nitrate nitrogen monitoring probe; 20-PLC control system; 21-Computer control system; 22-Microporous aeration disc; 23-Flow meter; 24-Air pump; 25-Dissolved oxygen monitoring probe; 26-Air outlet; 27-Air collection bag. Detailed Implementation

[0048] This invention provides a wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions, comprising the following steps:

[0049] 1) Surface activation was achieved by mixing and soaking polyurethane sponge with sodium hydroxide solution;

[0050] The surface-activated polyurethane sponge was mixed with a reducing agent and solutions of divalent manganese salts of different concentrations for impregnation and loading. After impregnation and loading were completed, the polyurethane sponge with divalent manganese loaded on the surface was mixed with a solution of a crosslinking agent for crosslinking and fixation, thus obtaining polyurethane sponge filler with divalent manganese loaded on the surface.

[0051] 2) Microbial enrichment culture of activated sludge was carried out using polyurethane sponge packing material loaded with divalent manganese to obtain acclimatized activated sludge.

[0052] 3) Use the acclimated activated sludge obtained in step 2) to perform autotrophic denitrification treatment on 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 This is a schematic diagram illustrating the mechanism of manganese oxidation coupled with denitrification. The specific principle is as follows: Mn(II) is oxidized to Mn(IV) extracellularly by enzymes secreted by microorganisms, releasing electrons in this process. These released electrons can be transferred into the cell to reduce nitrate. Nitrate reductase (Nar) then converts NO3- into nitrate. - -N is converted to NO2 --N, nitrite reductase (Nir) converts NO2 - Nitric oxide (NO) is converted to nitrogen (N), and nitric oxide reductase (Nor) converts NO to N₂O. Nitrous oxide reductase (Nos) then reduces N₂O back to N₂, completing the nitrogen conversion. This process involves electron transfer, accompanied by energy production and utilization, providing energy for microbial life activities and enabling the conversion of Mn(II) and NO₃⁻ in wastewater. - -N synchronization removal.

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

[0056] In this invention, the divalent manganese salt in step 1) includes manganese chloride and / or manganese sulfate, preferably manganese sulfate; the concentration of the divalent manganese salt solution 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 more preferably 0.5 to 0.7 mol / L.

[0057] In this 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 divalent manganese salt solution is 0.05-0.5:100, preferably 0.1-0.45:100, more preferably 0.15-0.4:100, and even more preferably 0.2-0.3:100.

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

[0059] In this invention, the atmosphere for impregnation load in step 1) is an oxygen-free atmosphere.

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

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

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

[0063] Polyurethane sponge packing material loaded with divalent manganese was mixed with activated sludge, and then artificial wastewater was introduced to perform gradient acclimatization of the activated sludge. When the influent NO3 of the artificial wastewater... - -N concentration is 50 mg / L, NO3 in effluent - When the -N removal rate is ≥90%, the activated sludge acclimatization is completed, and acclimatized activated sludge is obtained.

[0064] Among them, under each gradient, the effluent NO3 - -When the removal rate of -N is ≥90%, proceed to the next gradient;

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

[0066] In this invention, the gradient acclimatization is preferably achieved by setting different NO3 levels. - Artificial wastewater with NO3-N gradient concentrations increases with acclimatization time. - The concentration of -N increases with the gradient.

[0067] In this invention, the release rate of divalent manganese ions when the divalent manganese-loaded polyurethane sponge filler is immersed in water is: 3.3-3.7 mg / (g·d) for days 1-6 and 1.8-2.2 mg / (g·d) for days 7-30. This parameter was obtained by testing actual polyurethane sponge fillers.

[0068] During the microbial enrichment culture process, the release of divalent manganese and NO3 from the artificial wastewater is controlled by adjusting the filling quality of the polyurethane sponge filler loaded with divalent manganese. - The molar ratio of -N is 1:1.1, preferably 1:1.

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

[0070] In this invention, the artificial wastewater comprises the following components at 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, and 0.06 mL / L trace element solution.

[0071] In this invention, the divalent manganese-loaded polyurethane sponge filler generates divalent manganese ions during the treatment process. By supplementing the divalent manganese-loaded polyurethane sponge filler, the generated divalent manganese ions react with NO3 in the artificial wastewater. - The molar ratio of -N is 1.

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

[0073] In this invention, the trace element solution contains the following concentrations of substances: 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 this invention, the artificial wastewater is kept for 23 to 47 hours in each cycle during acclimatization. The first cycle has a retention time of 23 to 30 hours, the second cycle has a retention time of 30 to 40 hours, and the third cycle has a retention time of 40 to 37 hours. The retention time increases with each cycle.

[0075] In this invention, the effluent NO3 - The method for calculating the -N removal rate is as follows:

[0076]

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

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

[0079] In this invention, during the autotrophic denitrification treatment of the wastewater, the release of divalent manganese and NO3 from the artificial wastewater is controlled by adjusting the filling quality of the polyurethane sponge filler loaded with divalent manganese. - The molar ratio of -N is 1:1

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

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

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

[0083] In this invention, the wastewater denitrification process utilizing divalent manganese ions for autotrophic denitrification is preferably carried out in a sequencing batch reactor (SBR) device.

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

[0085] The inlet tank 1 is connected to the pool body 16 via the inlet pipe 4 and the inlet pump 5. The pool body is connected to the outlet tank 14 via the outlet pipe 11 and the outlet pump 17. The pool body 16 is equipped with a stirring paddle 10, a nitrate nitrogen monitoring probe 19, a microporous aeration disc 22, and a dissolved oxygen monitoring probe 25. The inlet tank 1 is equipped with 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. The pool body 16 is equipped with a water bath jacket and is connected to the constant temperature water bath 13 via the circulation pump 18 and the circulation inlet pipe 12.

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

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

[0088] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0089] Example 1

[0090] 1) The polyurethane sponge was immersed in ethanol and ultrasonically cleaned for 30 minutes to remove surface impurities, then dried at 60℃ for later use. Next, it was immersed in a 1 mol / L NaOH solution at 60℃ for 2 hours for surface activation. Then, it was repeatedly rinsed with deionized water until neutral and dried for later use. The polyurethane sponge was then impregnated in a manganese sulfate solution, subjected to a vacuum gradient impregnation and loading process three times. The manganese sulfate solution concentration gradient was 1–0.5–0.2 mol / L, and the gradient concentration manganese sulfate solution also contained 1% ascorbic acid by mass. The impregnated and loaded polyurethane sponge was then immersed in an 8% glutaraldehyde solution for 3 hours for cross-linking fixation. Finally, it was vacuum dried at 60℃ for 24 hours to obtain a sponge filler loaded with divalent manganese. During the above surface activation, impregnation and loading, and cross-linking fixation processes, the solution must completely cover the polyurethane sponge.

[0091] 2) The surface loading of divalent manganese in the sponge packing is 100 mg / g. The manganese release rate is 3.5 mg / (g·d) within 1–6 days and 2 mg / (g·d) within 7–30 days. The manganese release rate is controlled to be in line with the NO3 content in the wastewater. - The molar ratio of -N content is 1:1, based on the NO3 content in the wastewater to be treated. - To supplement the -N content of the filler, first fill the cavity with 5.7g of divalent manganese-loaded polyurethane sponge filler as follows: Figure 2 The sequencing batch reactor shown in Figure 16 (effective volume 5L, diameter 18cm, height 25cm) is then filled with 3L of activated sludge from the secondary sedimentation tank of a wastewater treatment plant (suspended solids concentration 3500mg / L).

[0092] Prepare formulations containing different concentrations of nitrate nitrogen (NO3) - Artificial wastewater containing NO3- (N) -The concentration gradient of -N was 20 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, and the pH value was 6.7 ± 0.1. In addition, the artificial wastewater also contains the following components at 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, and 0.06 mL / L trace element solution. The trace element solution contains the following substances at 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) Nitrate nitrogen (NO3) is introduced through inlet pipe 4. - Artificial wastewater with a NO concentration of 20 mg / L was introduced into tank 16 at a rate of 1.1 mL / min. Agitator 10 stirred the water at a rate of 20 r / min. Microporous aeration discs introduced nitrogen into the system to maintain DO < 0.5 mg / L (hydraulic retention time was 24 h, including 15 h of influent, 24 h of stirring, 50 min of sedimentation, and 10 min of effluent). After 3 months, the effluent NO3... - -N removal rate stabilized at 90%, completing the first stage of acclimatization.

[0094] 4) Nitrate nitrogen (NO3) is used sequentially. - Artificial wastewater with NO3- concentrations of 30 mg / L, 40 mg / L, and 50 mg / L was subjected to repeated steps in step 3) to acclimatize the sludge in tank 16. The corresponding amounts of divalent manganese-loaded polyurethane sponge filler for the above wastewater concentrations were 7.9 g, 10.5 g, and 13.2 g, respectively. When the influent NO3- - -N concentration reaches 50mg / L, NO3 in effluent - The domestication was completed when the -N removal rate reached a stable 90%. The composition of the microbial community was determined by high-throughput sequencing technology, which included three dominant bacteria: Ca.N.manganoxidans, Ca.N.manganoxydans, and Ca.N.manganoxidant.

[0095] 5) The acclimated sludge was used to treat the domestic wastewater that had undergone primary treatment in the sewage treatment plant. The water quality of the domestic wastewater is shown in Table 1.

[0096] 8.6g of sponge packing loaded with divalent manganese was added to tank 16 to maintain the manganese release during treatment and the NO3 content in the wastewater. - The molar ratio of -N was 1:1. The pH of the domestic wastewater was then adjusted to 6.7 ± 0.1, and the wastewater was introduced into the bottom of tank 16 at a flow rate of 3.7 mL / min. The hydraulic retention time was 15 hours, including 9 hours of influent, 15 hours of stirring, 50 minutes of sedimentation, and 10 minutes of effluent. The temperature inside tank 16 was controlled at 35℃ using a constant temperature water bath 13. After treatment, the supernatant was pumped into the effluent tank 14, and the water in the effluent tank was immediately sampled and filtered using a 5 mL syringe. Testing showed that the nitrate nitrogen in the effluent was 3 mg / L, with a removal rate of 90%; the N2O accumulation was 0.001 mg N / L.

[0097] Table 1 Water quality indicators of domestic wastewater from the sewage treatment plant after primary treatment.

[0098] numerical values 30 40 8.0

[0099] Example 2

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

[0101] 5) The acclimated sludge was used to treat the industrial wastewater. The water quality of the industrial wastewater is shown in Table 2.

[0102] 14.3g of sponge packing loaded with divalent manganese was added to tank 16 to maintain the manganese release during treatment and the NO3 in the wastewater. - The molar ratio of -N was 1:1. The industrial wastewater was then diluted and the pH was adjusted to 6.7 ± 0.1 before being introduced into the bottom of tank 16 at a flow rate of 2.2 mL / min. The hydraulic retention time was 24 hours, including 15 hours of influent, 24 hours of stirring, 50 minutes of sedimentation, and 10 minutes of effluent. The temperature within tank 16 was controlled at 35℃ using a constant-temperature water bath 13. After treatment, the supernatant was pumped into the effluent tank 14, and a 5 mL syringe was immediately used to sample and filter the water. Testing showed that the nitrate nitrogen in the effluent was 5 mg / L, with a removal rate of 90%; the N2O accumulation was 0.001 mg N / L.

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

[0104] numerical values 2000 600 7.0 After dilution 50 15 /

[0105] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions, characterized in that, Includes the following steps: 1) The polyurethane sponge was mixed with sodium hydroxide solution for surface activation; the surface-activated polyurethane sponge was mixed with reducing agent and solutions of divalent manganese salts of different concentrations, and impregnated and loaded under an oxygen-free atmosphere. After the impregnation and loading were completed, the polyurethane sponge with divalent manganese loaded on the surface was mixed with a solution of crosslinking agent for crosslinking and fixation, so as to obtain polyurethane sponge filler with divalent manganese loaded on the surface. 2) Microbial enrichment culture of activated sludge was carried out using polyurethane sponge packing material loaded with divalent manganese to obtain acclimatized activated sludge. 3) Use the acclimated activated sludge obtained in step 2) to autotrophically denitrify the wastewater to be treated, and complete the wastewater denitrification process; The microorganisms include one or more of Ca.N. manganoxidans, Ca.N. manganoxydans and Ca.N. manganoxidant; The concentration of the sodium hydroxide solution in step 1) is 1~2 mol / L, the surface activation time is 1~3 h, and the temperature is 50~70℃; The divalent manganese salt includes manganese chloride and / or manganese sulfate; the concentration of the solution of the divalent manganese salt 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 time is 3-4 hours, and the impregnation temperature is 30-40°C. The crosslinking agent is glutaraldehyde and / or polyethyleneimine, and the mass concentration of the crosslinking agent solution is 8%. The cross-linking fixation temperature is 30~40℃, and the cross-linking fixation time is 2~3h; The microbial enrichment culture process described in step 2) is as follows: Polyurethane sponge packing material loaded with divalent manganese was mixed with activated sludge, and then artificial wastewater was introduced to perform gradient acclimation of the activated sludge. The gradient acclimation involved setting different NO3 levels. - Artificial wastewater with NO3-N gradient concentrations increases with acclimatization time. - The concentration of -N increases with the gradient, when the influent NO3 in the artificial wastewater - -N concentration is 50 mg / L, NO3 in effluent - When the -N removal rate is ≥90%, the activated sludge acclimatization is completed, and acclimatized activated sludge is obtained. Among them, under each gradient, the effluent NO3 - -When the removal rate of -N is ≥90%, proceed to the next gradient; NO3 in the artificial wastewater - The concentration of -N is 20~50 mg / mL; The release rate of divalent manganese ions from the polyurethane sponge filler loaded with divalent manganese when immersed in water is: 3.3~3.7 mg / (g·d) on days 1-6 and 1.8~2.2 mg / (g·d) on days 7-30. During the microbial enrichment culture process, the release of divalent manganese and NO3 from the artificial wastewater is controlled by adjusting the filling quality of the polyurethane sponge filler loaded with divalent manganese. - The molar ratio of -N is 1:1 to 1.1; The suspended solids concentration of the activated sludge is 3000~4000 mg / L; In step 2), during the microbial enrichment culture, and in step 3), during the wastewater treatment process, the oxygen content in the system is independently DO ≤ 0.5 mg / L, and the temperature is independently 30~35℃. During the autotrophic denitrification treatment of the wastewater, the release of divalent manganese from the polyurethane sponge filler, which is loaded with divalent manganese, is controlled by adjusting the filling quality of the filler. This control is crucial for the reaction between the released divalent manganese and NO3 in the artificial wastewater. - The molar ratio of -N is 1:1; The wastewater denitrification process utilizing divalent manganese ions for autotrophic denitrification is carried out within a sequencing batch reactor (SBR) device.

2. The wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions according to claim 1, characterized in that, The artificial wastewater comprises the following components at 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, and 0.06 mL / L trace element solution; The pH value of the artificial wastewater is 6.5~7.

0.

3. The wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions according to claim 2, characterized in that, The trace element solution contains the following concentrations of substances: 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 LEDTA.

4. A wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions according to any one of claims 1 to 3, characterized in that, The artificial wastewater influent rate during acclimatization was 1.11~2.22 mL / min, and the residence time for each cycle was 23~47 h.

5. The wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions according to claim 4, characterized in that, The effluent NO3 - The method for calculating the -N removal rate is as follows: Where C0 and V0 are the NO3 entering the reactor in this cycle, respectively. - -N concentration and volume; C1 and V1 are the NO3 concentration and volume in the reactor at the end of the previous cycle, respectively. - -N concentration and volume; C2 and V2 are NO3 in the reactor at the end of this cycle, respectively. - -N concentration and volume.

6. The wastewater denitrification process utilizing autotrophic denitrification of divalent manganese ions according to claim 1, characterized in that, The NO3 in the wastewater to be treated mentioned in step 3) - -N concentration ≤50mg / L, NO3 in the wastewater to be treated after autotrophic denitrification. - -N concentration ≤ 5 mg / L; The wastewater is stirred during the treatment process at a rate of 20-30 r / min. The pH value of the wastewater to be treated is 6.5~7.0.

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