Method and application for preparing sulfur-iron-based autotrophic denitrification filler by mechanochemical method

Abstract

The present invention discloses a method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemistry and its application. The method includes: taking elemental sulfur powder, divalent iron source and activated carbon powder and ball-milling them in a ball mill for 2 to 4 hours to obtain a powdery composite material; heating and melting the powdery composite material to obtain a molten composite material; granulating the molten composite material first and then cooling it, or directly cooling and solidifying the molten composite material and then crushing it to obtain the sulfur-iron-based autotrophic denitrification filler; the total mass percentage of the elemental sulfur powder and the divalent iron source is 80% to 90%, and the mass percentage of the activated carbon powder is 10% to 20%; and the mass ratio of the elemental sulfur powder to the divalent iron source is 1:1 to 7:3. The denitrification and phosphorus removal effects of the sulfur-iron-based autotrophic denitrification filler prepared by the present invention are enhanced, and it can be applied to the denitrification and phosphorus removal of the effluent from the secondary sedimentation tank of a sewage treatment plant, constructed wetland, industrial wastewater, etc.

Description

Technical Field

[0001] This application belongs to the technical field of deep denitrification and phosphorus removal, and specifically relates to a method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemistry and its application. Background Art

[0002] Elemental sulfur S 0 Autotrophic denitrification driven by elemental sulfur is regarded as the most promising process for large-scale application. Compared with the heterotrophic denitrification system, autotrophic denitrification driven by elemental sulfur has the advantages of more complete denitrification, low cost, and low risk. However, the existing system still has the problems of low biological utilization rate, low effluent pH, and high sulfate concentration, which restrict the denitrification efficiency, process safety, and process stability of autotrophic denitrification. Therefore, there is an urgent need for autotrophic denitrification fillers with high denitrification efficiency, good stability, and green safety. The key problem restricting the performance and application of autotrophic denitrification driven by elemental sulfur is the low biological utilization rate of elemental sulfur. Low water solubility, strong hydrophobicity, and poor biocompatibility are the main reasons for the low biological utilization rate of elemental sulfur. In addition, elemental sulfur is soft and light, and it is easy to flow out with the effluent, which will also reduce the utilization rate.

[0003] The combination of elemental sulfur and iron-containing minerals can improve the denitrification performance, alleviate the decrease in pH and the generation of sulfate. In addition, the introduction of iron-containing minerals can achieve simultaneous phosphorus removal on the basis of denitrification. At present, most of the methods for preparing sulfur-iron-based autotrophic denitrification fillers by combining elemental sulfur and iron-containing minerals are: mixing elemental sulfur and iron-containing minerals and then melting and granulating, or melting elemental sulfur first and then adding iron-containing minerals and mixing and granulating. However, there is still room for further improvement in the biological utilization rate and denitrification and phosphorus removal effects of sulfur-iron-based autotrophic denitrification fillers. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemistry and its application, so as to improve the biological utilization rate of the prepared sulfur-iron-based autotrophic denitrification filler and strengthen deep denitrification and phosphorus removal.

[0005] On the one hand, this application provides a method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemistry, including:

[0006] Taking elemental sulfur powder, divalent iron source and activated carbon powder and putting them into a ball mill for ball milling for 2-4 hours to obtain a powdery composite material;

[0007] Heating and melting the powdery composite material to obtain a molten composite material;

[0008] Granulating the molten composite material first and then cooling it, or directly cooling and solidifying the molten composite material and then crushing it to obtain the sulfur-iron-based autotrophic denitrification filler;

[0009] The total mass percentage of the above-mentioned elemental sulfur powder and the above-mentioned divalent iron source is 80% to 90%, and the mass percentage of the above-mentioned activated carbon powder is 10% to 20%; and the mass ratio of the above-mentioned elemental sulfur powder to the above-mentioned divalent iron source is 1:1 to 7:3.

[0010] Furthermore, the mass ratio of the elemental sulfur powder to the divalent iron source is preferably 7:3.

[0011] In some embodiments, the divalent iron source is selected from ferrous carbonate and / or ferrous sulfide, and ferrous sulfide is preferred.

[0012] In some embodiments, the powdery composite material is heated and melted, specifically: the powdery composite material is heated to 120°C to 140°C to make it melt.

[0013] In some embodiments, the rotation speed of the ball mill is 200 to 600 rpm, preferably 400 rpm.

[0014] In some embodiments, the mass ratio of the ball milling medium to the raw materials is 4:1, and the raw materials include elemental sulfur powder, divalent iron source and activated carbon powder; the ball milling medium can be stainless steel ball milling beads.

[0015] The method of this application uses solid substances as raw materials, and pre-treats the raw materials by a mechanochemical method based on high-energy ball milling to assist in the preparation of sulfur-iron-based autotrophic denitrification fillers. The prepared sulfur-iron-based autotrophic denitrification fillers have a uniform bulk phase, controllable size, and significantly improved denitrification and phosphorus removal effects.

[0016] During the ball milling process, the ball milling medium balls collide with the solid raw materials at high speed, thereby introducing a large number of defects into the solid particles, forming a metastable state, and improving the surface activity of the particles. In the metastable state, the elemental sulfur powder can form various different sulfur forms, and the elemental sulfur powder can in-situ generate solid sulfur ions S n 2- , on the one hand, the sulfur ion S n 2- can reduce the hydrophobicity of the elemental sulfur powder, which helps to improve the biological utilization rate of the elemental sulfur powder; on the other hand, the sulfur ion S n 2- can promote the electron transfer between microorganisms and S 0 particles, which helps to enhance the effect and efficiency of denitrification and phosphorus removal. The divalent iron source is preferably ferrous sulfide, and FeS with semiconductor properties can be in-situ generated during the ball milling process n , which can further promote electron transfer and helps to obtain better denitrification and phosphorus removal effects and efficiency.

[0017] On the other hand, this application provides the application of the sulfur-iron-based autotrophic denitrification filler prepared by the above method in the denitrification and phosphorus removal process, for example, it can be applied to the denitrification and phosphorus removal of the effluent from the secondary sedimentation tank of a sewage treatment plant, constructed wetland, and industrial wastewater.

[0018] In some embodiments, the dosage of the sulfur-iron-based autotrophic denitrification filler is 20 - 40 g / L.

[0019] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0020] (1) The raw materials of the method of the present application are safe, the components are stable, and the cost is low; no solvent is used in the preparation process, which is green, environmentally friendly and efficient, and is easy to scale up production.

[0021] (2) The present application introduces high-energy ball milling to pretreat the solid raw materials. A variety of sulfur forms can be in-situ generated from the elemental sulfur powder, which increases the content of polysulfides in the filler and can avoid the deficiencies of the elemental sulfur powder itself (such as low water solubility and strong hydrophobicity); moreover, high-energy ball milling also introduces a large number of defects into the solid particles, which can significantly improve the surface activity of the particles. Compared with the traditional method, the filler prepared by the method of the present application has a uniform bulk phase, controllable size, and the denitrification and phosphorus removal effects are also significantly enhanced. Description of the Drawings

[0022] Figure 1 is the XPS spectrum of the sample of Example 1;

[0023] Figure 2 is the morphology and proportion of sulfur elements in the sample of Example 1;

[0024] Figure 3 is the comparison chart of the denitrification rates of the samples of the examples and the comparative examples;

[0025] Figure 4 is the phosphorus removal efficiency of the samples of the examples and the comparative examples. Detailed Embodiments

[0026] In order to make the purpose, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with reference to the embodiments.

[0027] Example 1

[0028] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0029] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0030] (2) Put 56 g of elemental sulfur powder, 24 g of ferrous carbonate and 20 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set to 400 rpm, and the ball milling time is set to 4 h;

[0031] (3) After the ball milling is completed, take out the powdery composite material and heat the powdery composite material to 140 °C to obtain a molten composite material;

[0032] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain the sample of sulfur-iron-based autotrophic denitrification filler.

[0033] Figure 1 The XPS spectrum of the sample of this example is shown. It can be seen from the XPS spectrum that the sample contains S n 2- . Figure 2 The sulfur forms and their respective proportions in the sample of this example are shown. From Figure 2 it can be known that in the sample of this example, sulfur elements not only exist in the form of elemental S 0 but also include S n 2- , S2 2- , SO4 2- , SO3 2- and other sulfur forms. In particular, S n 2- , which is an extracellular redox mediator, can promote the transfer of electrons between microorganisms and S 0 particles, and is beneficial to significantly improving the effect of nitrogen and phosphorus removal.

[0034] The following method is used to detect the nitrogen and phosphorus removal effects of the sample of this example, including:

[0035] (1) Prepare synthetic sewage with the main pollutants at the secondary effluent concentration: Add the chemicals KNO3, KH2PO4, NaHCO3, MgCl2·6H2O and FeSO4·7H2O to deionized water; among them, the concentration of KNO3 is 0.3 g / L, the concentration of nitrate nitrogen NO3-N is 20 mg / L, the concentration of KH2PO4 is 0.0509 g / L, the total phosphorus concentration is 10 mg / L in total, the concentration of NaHCO3 is 0.1 g / L, the concentration of MgCl2·6H2O is 0.1 g / L, and the concentration of FeSO4·7H2O is 0.005 g / L.

[0036] (2) Take 1000 mL of synthetic sewage and add it to a 1000 mL conical flask, add 30 g of the sulfur-iron-based autotrophic denitrification filler sample, then add the activated sludge suspension, and finally cover the conical flask with a rubber stopper and seal it. Punch a hole in the rubber stopper and insert a glass tube with a diameter of 0.8 cm, and connect the glass tube to a rubber tube outside, and fasten the rubber stopper.

[0037] (3) Pass nitrogen into the conical flask through the rubber tube for 15 minutes of stripping, and use a stopcock to seal the rubber tube. Then place the conical flask in a constant temperature shaker, set the temperature to 30 °C and the rotation speed to 150 rpm, take samples at fixed times. When sampling, use a disposable syringe to extract 5 mL, and quickly measure the nitrate nitrogen and total phosphorus contents of the sampled samples after passing through a 0.45 μm filter membrane, and calculate the nitrogen removal rate and total phosphorus removal rate.

[0038] After detection, the nitrogen removal rates of the samples in this example were 11.1%, 27.8%, and 100% at 30 min, 2 h, and 98 h of reaction, respectively, and the total phosphorus removal rate reached 87.3%.

[0039] Example 2

[0040] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0041] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling jar;

[0042] (2) Take 40 g of elemental sulfur powder, 40 g of ferrous carbonate, and 20 g of activated carbon powder and place them in the stainless steel ball milling jar for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set to 400 rpm, and the ball milling time is set to 4 h;

[0043] (3) After the ball milling is completed, take out the powdered composite material and heat the powdered composite material to 140 °C to obtain a molten composite material;

[0044] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0045] The phosphorus and nitrogen removal effects of the samples in this example were detected. The method was the same as the phosphorus and nitrogen removal effect detection method in Example 1. After detection, the nitrogen removal rates of the samples in this example were 10.1%, 11.2%, and 77.0% at 30 min, 2 h, and 98 h of reaction, respectively, and the total phosphorus removal rate was as high as 95.8%.

[0046] Example 3

[0047] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0048] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling jar;

[0049] (2) Take 24 g of elemental sulfur powder, 56 g of ferrous carbonate, and 20 g of activated carbon powder and place them in the stainless steel ball milling jar for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set to 400 rpm, and the ball milling time is set to 4 h;

[0050] (3) After the ball milling is completed, take out the powdered composite material and heat the powdered composite material to 140 °C to obtain a molten composite material;

[0051] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0052] The phosphorus and nitrogen removal effects of the sample in this example were detected using the same method as in Example 1. After detection, the nitrogen removal rates of the sample in this example were 6.8% and 93.4% at 30 min and 98 h of reaction, respectively. However, in this example, due to the too low mass ratio of sulfur powder, it was difficult to heat and melt, and granulation was difficult.

[0053] Example 4

[0054] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0055] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0056] (2) Put 56 g of elemental sulfur powder, 24 g of ferrous carbonate and 20 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set at 200 rpm, and the ball milling time is set at 4 h;

[0057] (3) After the ball milling is completed, take out the powdery composite material and heat it to 140 °C to obtain a molten composite material;

[0058] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0059] The phosphorus and nitrogen removal effects of the sample in this example were detected using the same method as in Example 1. After detection, the nitrogen removal rates of the sample in this example were 14.7%, 17.7% and 63.8% at 30 min, 2 h and 98 h of reaction, respectively.

[0060] Example 5

[0061] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0062] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0063] (2) Put 56 g of elemental sulfur powder, 24 g of ferrous carbonate and 20 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set at 600 rpm, and the ball milling time is set at 4 h;

[0064] (3) After the ball milling is completed, take out the powdery composite material and heat it to 140 °C to obtain a molten composite material;

[0065] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0066] The phosphorus and nitrogen removal effects of the sample in this example were detected. The method was the same as that for detecting the phosphorus and nitrogen removal effects in Example 1. After detection, the nitrogen removal rates of the sample in this example were 10.8% and 99.8% at 30 min and 98 h of reaction, respectively. However, in this example, due to the excessive ball milling energy, the materials were extremely prone to agglomeration, and the sample yield was only about 30%. It should be noted that the yield refers to the mass ratio of the final powdered filler obtained after sieving to all raw materials.

[0067] Example 6

[0068] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0069] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0070] (2) Put 63 g of elemental sulfur powder, 27 g of ferrous carbonate, and 10 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained. The rotation speed of the planetary ball mill is set at 400 rpm, and the ball milling time is set at 4 h;

[0071] (3) After the ball milling is completed, take out the powdered composite material and heat the powdered composite material to 140 °C to obtain a molten composite material;

[0072] (4) Directly cool and solidify the molten composite material, and crush the obtained solid material to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0073] The phosphorus and nitrogen removal effects of the sample in this example were detected. The method was the same as that for detecting the phosphorus and nitrogen removal effects in Example 1. After detection, the nitrogen removal rates of the sample in this example were 14.5% and 100% at 30 min and 98 h of reaction, respectively. However, in this example, the dosage proportion of the activated carbon powder was relatively low, only accounting for 10% of the total amount of the materials, the dispersibility decreased, the materials were extremely prone to agglomeration, and the sample yield was relatively low, about 70%.

[0074] Example 7

[0075] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0076] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0077] (2) Put 56 g of elemental sulfur powder, 24 g of ferrous sulfide, and 20 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained. The rotation speed of the planetary ball mill is set at 400 rpm, and the ball milling time is set at 4 h;

[0078] (3) After the ball milling is completed, take out the powdered composite material and heat the powdered composite material to 140 °C to obtain a molten composite material;

[0079] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain a sample of sulfur-iron-based autotrophic denitrification filler.

[0080] Detect the phosphorus and nitrogen removal effects of the sample in this example. The method is the same as the phosphorus and nitrogen removal effect detection method in Example 1. After detection, when the reaction time of the sample in this example is 30 min, 2 h, and 98 h, the nitrogen removal rates are 3.2%, 4.8%, and 96.3% respectively, and the total phosphorus removal rate can reach 100%.

[0081] Example 8

[0082] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0083] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0084] (2) Put 56 g of elemental sulfur powder, 24 g of ferrous carbonate, and 20 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set at 400 rpm, and the ball milling time is set at 4 h;

[0085] (3) After the ball milling is completed, take out the powdered composite material and heat the powdered composite material to 140 °C to obtain a molten composite material;

[0086] (4) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain a sample of sulfur-iron-based autotrophic denitrification filler.

[0087] The following method is used to detect the phosphorus and nitrogen removal effects of the sample in this example, including:

[0088] (1) Prepare synthetic sewage with the main pollutants formulated according to the secondary effluent concentration: Add the chemicals KNO3, KH2PO4, NaHCO3, MgCl2·6H2O, and FeSO4·7H2O to deionized water; among them, the concentration of KNO3 is 0.6 g / L, the concentration of nitrate nitrogen NO3-N is 40 mg / L, the concentration of KH2PO4 is 0.0509 g / L, the total phosphorus concentration is 10 mg / L, the concentration of NaHCO3 is 0.1 g / L, the concentration of MgCl2·6H2O is 0.1 g / L, and the concentration of FeSO4·7H2O is 0.005 g / L.

[0089] (2) Add 1000 mL of synthetic sewage into a 1000 mL conical flask, add 30 g of the sulfur-iron-based autotrophic denitrification filler sample, then add the activated sludge suspension, and finally cover it with a rubber stopper and seal the conical flask. Punch a hole in the rubber stopper and insert a glass tube with a diameter of 0.8 cm, and connect the external rubber tube to the glass tube, then fasten the rubber stopper.

[0090] (3) Pass nitrogen into the conical flask through the rubber tube for 15 minutes of stripping, and use a stopcock to seal the rubber tube. Then place the conical flask in a constant temperature shaker, set the temperature to 30 °C, the rotation speed to 150 rpm, and sample at fixed times. When sampling, use a disposable syringe to extract 5 mL, and quickly measure the nitrate nitrogen and total phosphorus contents of the sampled water after passing through a 0.45 μm filter membrane, and calculate the nitrogen removal rate and total phosphorus removal rate.

[0091] After testing, for the sample of this example, the nitrogen removal rates at 30 minutes, 2 hours, and 98 hours of the reaction are 10.2%, 10.9%, and 19.3% respectively, and the total phosphorus removal rate can reach 87.3%.

[0092] Example 9

[0093] The specific steps for preparing the sulfur-iron-based autotrophic denitrification filler in this example are as follows:

[0094] (1) Put 400 g of stainless steel ball milling beads into a 500 mL stainless steel ball milling tank;

[0095] (2) Put 56 g of elemental sulfur powder, 24 g of ferrous carbonate, and 20 g of activated carbon powder into the stainless steel ball milling tank for ball milling. No atmosphere protection is required during the ball milling process, and normal temperature and pressure are maintained; the rotation speed of the planetary ball mill is set to 400 rpm, and the ball milling time is set to 4 hours;

[0096] (3) After the ball milling is completed, take out the powdered composite material and heat the powdered composite material to 140 °C to obtain a molten composite material;

[0097] (4) Directly cool and solidify the molten composite material, and crush the obtained solid material to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0098] The following method is used to detect the phosphorus and nitrogen removal effects of the sample of this example, including:

[0099] (1) The synthetic sewage is prepared by formulating the main pollutants according to the secondary effluent concentration: Add the chemicals KNO3, KH2PO4, NaHCO3, MgCl2·6H2O, and FeSO4·7H2O into deionized water; among them, the concentration of KNO3 is 0.15 g / L, the concentration of nitrate nitrogen NO3-N is 10 mg / L, the concentration of KH2PO4 is 0.0509 g / L, and the total phosphorus concentration is 10 mg / L in total, the concentration of NaHCO3 is 0.1 g / L, the concentration of MgCl2·6H2O is 0.1 g / L, and the concentration of FeSO4·7H2O is 0.005 g / L.

[0100] (2) Take 1000 mL of the synthetic sewage and add it to a 1000 mL conical flask, add 30 g of the sulfur-iron-based autotrophic denitrification filler sample, then add the activated sludge suspension, and finally cover it with a rubber stopper and seal the conical flask. Punch a hole in the rubber stopper and insert a glass tube with a diameter of 0.8 cm, and connect a rubber tube outside the glass tube, and fasten the rubber stopper.

[0101] (3) Pass nitrogen into the conical flask through the rubber tube for stripping for 15 min, and use a stopcock to seal the rubber tube. Then place the conical flask in a constant temperature shaker, set the temperature to 30 °C, the rotation speed to 150 rpm, sample at fixed times. When sampling, use a disposable syringe to extract 5 mL, and quickly measure the nitrate nitrogen and total phosphorus contents of the sampled water after passing through a 0.45 μm filter membrane, and calculate the nitrogen removal rate and total phosphorus removal rate.

[0102] After testing, for the sample in this example, at 30 min, 2 h, and 98 h of the reaction, the nitrogen removal rates are 6.2%, 8.3%, and 100% respectively, and the total phosphorus removal rate can reach 87.3%.

[0103] It should be noted that except for Examples 5 and 6, the sample yields of other examples are all as high as over 95%.

[0104] Comparative Example 1

[0105] When preparing the sulfur-iron-based autotrophic denitrification filler in this comparative example, the raw materials were not mechanically and chemically pretreated. The specific steps are as follows:

[0106] (1) Take 56 g of elemental sulfur powder and heat it to 140 °C to melt the elemental sulfur powder;

[0107] (2) Add 24 g of ferrous carbonate and 20 g of activated carbon powder and stir evenly to obtain a molten composite material;

[0108] (3) Directly cool and solidify the molten composite material, and crush the obtained solid to obtain the sulfur-iron-based autotrophic denitrification filler sample.

[0109] The phosphorus and nitrogen removal effects of this comparative example sample were detected by the same method as the phosphorus and nitrogen removal effect detection method in Example 1. After detection, the nitrogen removal rates of the sample in this example were 5.1%, 11.6% and 92.4% at 30 min, 2 h and 98 h of reaction, respectively, and the total phosphorus removal rate reached 69.3%.

[0110] Comparative Example 2

[0111] To fully illustrate the advantages of the sulfur-iron-based autotrophic denitrification filler prepared in this application, commercial sulfur particles were used as the denitrification filler in this comparative example, and its phosphorus and nitrogen removal effects were detected by the same method as the phosphorus and nitrogen removal effect detection method in Example 1. After detection, the nitrogen removal rates of the sample in this comparative example were 6.3%, 8.1% and 23.4% at 30 min, 2 h and 98 h of reaction, respectively, and there was no phosphorus removal effect.

[0112] Comparative Example 3

[0113] To fully illustrate the advantages of the sulfur-iron-based autotrophic denitrification filler prepared in this application, commercial sulfur-iron-based autotrophic denitrification materials were used as the denitrification filler in this comparative example, and its phosphorus and nitrogen removal effects were detected by the same method as the phosphorus and nitrogen removal effect detection method in Example 1. After detection, the nitrogen removal rates of the sample in this comparative example were 7.0%, 10.5% and 93.4% at 30 min, 2 h and 98 h of reaction, respectively, and there was no phosphorus removal effect.

[0114] Comparative Example 4

[0115] To exclude the influence of the chemical reduction effect of the filler on the experimental results, a control experiment without adding acclimated sludge was set up, including:

[0116] (1) Synthetic sewage was prepared with the main pollutants at secondary effluent concentration: chemicals KNO3, KH2PO4, NaHCO3, MgCl2·6H2O and FeSO4·7H2O were added to deionized water; among them, the concentration of KNO3 was 0.3 g / L, the concentration of nitrate nitrogen NO3-N was 20 mg / L, the concentration of KH2PO4 was 0.0509 g / L, the total phosphorus concentration was 10 mg / L in total, the concentration of NaHCO3 was 0.1 g / L, the concentration of MgCl2·6H2O was 0.1 g / L, and the concentration of FeSO4·7H2O was 0.005 g / L.

[0117] (2) 1000 mL of synthetic sewage was added to a 1000 mL conical flask, and an activated sludge suspension was added. Finally, a rubber stopper was put on and the conical flask was sealed. A hole was drilled in the rubber stopper and a glass tube with a diameter of 0.8 cm was inserted, and a rubber tube was connected to the outside of the glass tube, and the rubber stopper was fastened.

[0118] (3) Nitrogen was introduced into the conical flask through a rubber tube for stripping for 15 min, and the rubber tube was sealed with a stopcock. Then the conical flask was placed in a constant temperature shaker, with the temperature set at 30 °C and the rotation speed at 150 rpm. Samples were taken at fixed times. When sampling, 5 mL was extracted with a disposable syringe, and after passing through a 0.45 μm filter membrane, the nitrate nitrogen and total phosphorus contents of the sampled solution were quickly measured, and the nitrogen removal rate and total phosphorus removal rate were calculated.

[0119] After testing, at 30 min, 2 h, and 98 h of the reaction, the nitrogen removal rates were 7.3%, 10.4%, and 20.2% respectively. There was almost no phosphorus removal effect.

[0120] The above embodiments are only for clearly illustrating the made embodiments, rather than limiting the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Therefore, the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemical method, characterized in that, Comprising: Put elemental sulfur powder, divalent iron source and activated carbon powder into a ball mill and ball mill for 2 - 4 hours to obtain a powdery composite material; the rotation speed of the ball mill is 200 - 600 rpm; Heat the powdery composite material to melt it to obtain a molten composite material; Granulate the molten composite material first and then cool it, or directly cool and solidify the molten composite material and then crush it to obtain the sulfur-iron-based autotrophic denitrification filler; The total mass percentage of the elemental sulfur powder and the divalent iron source is 80% - 90%, and the mass percentage of the activated carbon powder is 10% - 20%; and the mass ratio of the elemental sulfur powder to the divalent iron source is 1:1 - 7:3; The divalent iron source is selected from ferrous carbonate and / or ferrous sulfide.

2. The method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemical method according to claim 1, characterized in that: The mass ratio of the elemental sulfur powder to the divalent iron source is 7:

3.

3. The method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemical method according to claim 1, characterized in that: The heating and melting of the powdery composite material specifically means: heating the powdery composite material to 120°C - 140°C to make it melt.

4. The method for preparing a sulfur-iron-based autotrophic denitrification filler by mechanochemical method according to claim 1, characterized in that: The rotation speed of the ball mill is 400 rpm.

5. Application of the sulfur-iron-based autotrophic denitrification filler prepared by the method according to any one of claims 1 - 4 in the nitrogen and phosphorus removal process.

6. The application according to claim 5, characterized in that: The nitrogen and phosphorus removal process is for nitrogen and phosphorus removal from the effluent of the secondary sedimentation tank of a sewage treatment plant, an artificial wetland or industrial wastewater.

7. The application according to claim 6, characterized in that: The dosage of the sulfur-iron-based autotrophic denitrification filler is 20 - 40 g / L.

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