Foamed porous core-shell type anaerobic ammonia oxidation-sulfur autotrophic composite filter material as well as preparation method and application of foamed porous core-shell type anaerobic ammonia oxidation-sulfur autotrophic composite filter material

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to a foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter material as well as a preparation method and application thereof. The preparation method comprises the following steps: by taking waste cyan asbestos and Bayer process red mud as main raw materials, a mixture of sodium tetraborate and cryolite as a fluxing agent and fermented waste biomass as a foaming agent, compacting, granulating and sintering to prepare a spherical filter material A1, and then coating an adhesion liquid containing dolomite, siderite and blue iron ore powder on the surface layer of A1 by adopting an electrostatic spraying adhesion technology to prepare the spherical filter material A1. The preparation method comprises the following steps: preparing an anaerobic ammoxidation filter material A1-A through high-temperature firing, coating the surface layer of A1 with an adhesion liquid containing gypsum, graphite and pyrite, and preparing a sulfur autotrophic filter material A1-S through high-temperature firing. The prepared filter materials A1-A and A1-S can effectively perform ecological niche separation on anaerobic ammonium oxidation bacteria and sulfur autotrophic bacteria, and malignant competition of the sulfur autotrophic bacteria on anaerobic ammonium oxidation is avoided, so that the autotrophic nitrogen removal effect is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and specifically relates to a foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter material and a preparation method and application thereof. Background Art

[0002] Anaerobic ammonium oxidation coupled with sulfur autotrophic denitrification is one of the hot research topics in the field of autotrophic denitrification in recent years. It has the advantages of high denitrification efficiency, no need for aeration and external carbon source, and low residual sludge production. 0 , S 2- , S 2 O 3 2- , H 2 S) is an electron donor, NO 3 - -N, NO 2 - -N is an electron acceptor, and denitrification is completed under the action of sulfur autotrophic bacteria. Compared with the traditional denitrification process, sulfur autotrophic has the advantages of economy, high efficiency, and low sludge production. However, the main challenges of sulfur autotrophic denitrification technology are: selecting a suitable sulfur source, the demand for alkalinity, and the reduction of sulfate and hydrogen sulfide in the effluent. Anaerobic ammonium oxidation technology has the advantages of no need for a carbon source, no requirement for alkalinity, no need for aeration, and no secondary pollution. It has attracted widespread attention in the field of denitrification. The current challenges facing anaerobic ammonium oxidation are mainly: the retention of anaerobic ammonium oxidizing microorganisms in the reactor, the improvement of anaerobic ammonium oxidation activity, and the removal of nitrates in the effluent.

[0003] Anaerobic ammonium oxidation coupled with sulfur autotrophic technology is a full-process autotrophic denitrification technology. Its core lies in the sulfur autotrophic removal of nitrates produced by anaerobic ammonium oxidation, thereby improving the theoretical maximum denitrification rate. At the same time, the alkalinity generated by the anaerobic ammonium oxidation process is supplemented to the sulfur autotrophic reaction, so that the overall denitrification is mainly dominated by anaerobic ammonium oxidation, so the production of secondary pollutants such as sulfate and hydrogen sulfide is effectively reduced. The main challenge of anaerobic ammonium oxidation coupled with sulfur autotrophic denitrification is that sulfur autotrophic denitrification bacteria may compete viciously with anaerobic ammonium oxidizing bacteria. In addition, sulfide may have a toxic effect on anaerobic ammonium oxidation, ultimately causing the decline of the anaerobic ammonium oxidizing community.

[0004] At present, China's invention patent 202410788494.8 has disclosed a system and method for deep denitrification of landfill leachate. In this method, the landfill leachate is subjected to anaerobic treatment and short-range nitrification treatment, and then enters the SBR type anaerobic ammonia oxidation coupled sulfur autotrophic unit. The coupled sludge is domesticated by inoculating anaerobic ammonia oxidation sludge and adding sodium sulfide induction. However, the required domestication period is as long as 180 days, and excessive addition of sodium sulfide may cause excessive proliferation of sulfur autotrophic bacteria, eventually leading to system collapse. In addition, China's invention patent 201910434 299.4 discloses an anaerobic ammonium oxidation coupled sulfur autotrophic denitrification denitrification device and a wastewater treatment method. This method uses a method of separating reactor compartments to separate anaerobic ammonium oxidation and sulfur autotrophic denitrification. However, this method requires inoculation of mature anaerobic ammonium oxidation granular sludge, which is difficult to obtain in practice. In addition, the use of sulfur granules as sulfur autotrophic carriers is prone to problems such as low mass transfer efficiency. Therefore, it is necessary to develop filter materials suitable for anaerobic ammonium oxidation coupled sulfur autotrophic systems to prevent vicious competition in anaerobic ammonium oxidation coupled sulfur autotrophic systems and effectively improve denitrification performance. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for preparing a foamed porous loaded filter material suitable for an anaerobic ammonia oxidation coupled sulfur autotrophic system. The prepared filter material can effectively separate the ecological niches of anaerobic ammonia oxidizing bacteria and sulfur autotrophic bacteria, avoiding the vicious competition of sulfur autotrophic bacteria on anaerobic ammonia oxidizing bacteria, thereby improving the autotrophic denitrification effect.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a method for preparing a foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter material, the method comprising the following steps:

[0008] S1. Using waste crocidolite and Bayer red mud (red mud produced by the Bayer process) as main raw materials, sodium tetraborate and cryolite powder as fluxing agents, and fermented waste biomass as foaming agent, the main raw materials, the fluxing agent and the foaming agent are mixed in water, and then wet-grinded to obtain a slurry;

[0009] S2, compacting and granulating the slurry described in S1, and then firing to obtain a foamed porous spherical filter material A1;

[0010] S3, mixing dolomite, siderite, blue iron ore powder with cationic polyacrylamide (CPAM) aqueous solution to prepare an attachment liquid, and then using electrostatic spray adhesion technology to wrap the attachment liquid on the surface of A1, and after firing, obtain the anaerobic ammonia oxidation filter material A1-A;

[0011] S4. Gypsum, graphite, pyrite powder and cationic polyacrylamide (CPAM) aqueous solution are mixed to prepare an attachment liquid, and the attachment liquid is wrapped on the surface of A1 by electrostatic spray adhesion technology. After oxygen-free high-temperature calcination, sulfur autotrophic filter material A1-S is obtained.

[0012] Preferably, the main components of the waste crocidolite include, by mass percentage: SiO 2 :45-55%, MgO: 28-33%, Fe 2 O 3 : 4-7%, Al 2 O 3 :2-6%, CaO: 1-5%, NiO: 1-3%, Na 2 O: 1-2%, K 2 O: 1-2%.

[0013] Preferably, by mass percentage, the main components of the Bayer process red mud include: Fe 2 O 3 : 35-40%, Al 2 O 3 : 20-25%, SiO 2 : 18-23%, Na 2 O: 8-12%, CaO: 3-7%, TiO 2 : 1-4%.

[0014] The present invention uses waste crocidolite and Bayer red mud as main raw materials, sodium tetraborate and cryolite mixture as flux, and fermented waste biomass as foaming agent, and obtains spherical filter material A1 after compaction, granulation and sintering, and then adopts electrostatic spray adhesion technology to wrap the attached liquid containing dolomite, siderite and blue iron ore powder on the surface of A1, and obtains anaerobic ammonia oxidation filter material A1-A through high-temperature firing, and also adopts electrostatic spray adhesion technology to wrap the attached liquid containing gypsum, graphite and pyrite on the surface of A1, and obtains sulfur autotrophic filter material A1-S through high-temperature firing. The prepared filter materials A1-A and A1-S can effectively separate the ecological niches of anaerobic ammonia oxidizing bacteria and sulfur autotrophic bacteria, avoid the vicious competition of sulfur autotrophic bacteria on anaerobic ammonia oxidation, and thus improve the autotrophic denitrification effect.

[0015] Preferably, in S1, the main raw material, flux, foaming agent and water are uniformly mixed in a mass percentage of 40-55%: 10-15%: 4-6%: 30-40% and then wet-ground using a zirconia bead mill to obtain a slurry.

[0016] Preferably, among the main raw materials, the waste crocidolite and Bayer process red mud are mixed in a mass ratio of 2 to 4:1.

[0017] Preferably, in the flux, the sodium tetraborate and cryolite powder are mixed in a mass ratio of 2:1.

[0018] Preferably, the firing temperature in S2 is 900-1000°C, the heating rate is 8-12°C / min, and the holding time is 20-40min.

[0019] Preferably, in S3, dolomite, siderite and blue iron ore powders are mixed in a mass ratio of 12-18:7-10:1-3, and then added to a 0.3‰ CPAM aqueous solution to prepare an attachment liquid, wherein the molecular weight of the CPAM is between 8 million and 12 million.

[0020] Preferably, in S4, gypsum, graphite and pyrite powder are mixed in a mass ratio of 5-11:13-27:3-7, and then added to a 0.3‰ CPAM aqueous solution to prepare an attachment liquid, wherein the molecular weight of the CPAM is between 8 million and 12 million.

[0021] Preferably, S3 is fired in a muffle furnace, the temperature is set to 500-600° C., and the time is 50-70 min.

[0022] Preferably, S4 uses a tube furnace in N 2 The calcination was carried out under atmosphere, the temperature was set to 500-600°C, and the time was 50-70min.

[0023] Preferably, the fermented waste biomass is obtained by composting and fermenting various waste biomass such as sawdust, egg shells, oyster shells, coconut shells, etc. The C / N of the waste biomass is 30-40, the moisture content is 35-50%, and the compost is turned over once every 3 days in the first two weeks, and then once a week.

[0024] Preferably, the main raw materials, waste crocidolite and Bayer red mud, are crushed and then screened through a 250-400 mesh sieve using a standard vibrating sieve machine.

[0025] Preferably, the electrostatic spray adhesion technology is used to wrap the attachment liquid on the surface of A1. The electrostatic adhesion technology is roughly based on the principle of using an electrostatic adhesion device in a high-voltage electrostatic field to use a strong voltage difference to enable the charged droplets to be quickly and evenly sprayed onto the surface of the A1 filler placed in the receiver, and in the process, the water can be evaporated to form micron or even nanometer-level solid microspheres. The electrostatic spray adhesion device includes: a high-voltage power supply, a receiver, an atomizing nozzle, and a constant-current injection pump. The high-voltage power supply can provide a voltage of 10-30KV, and a vibration device is provided at the bottom of the receiver to enable the A1 filler inside the receiver to roll evenly. The atomizing nozzle is 20-30cm away from the surface of the receiver.

[0026] The second aspect of the present invention provides foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter materials A1-A and A1-S prepared by the preparation method described in the first aspect.

[0027] The third aspect of the present invention provides the use of the foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter materials A1-A and A1-S described in the second aspect in treating sludge, wherein the sludge includes anaerobic ammonium oxidation sludge and anoxic biochemical sludge.

[0028] Preferably, the specific application method comprises the following steps:

[0029] S11, using filter media A1-A and A1-S to build a packed fixed bed, placing A1-A at the bottom, filling the filter media at a volume ratio of A1-A:A1-S=3-5:1, with a total filling rate of 60% to 80%, and the remaining volume is set as a sedimentation and clarification area;

[0030] S22, inoculated with anaerobic ammonium oxidation sludge and anoxic biochemical sludge, the MLSS of the two sludges after mixing is: 3000-5000mg / L;

[0031] S33, the reactor uses ammonia and nitrite mixed wastewater, and the inlet NO 2 - -N / NH 4 + -N=1-1.3.

[0032] Furthermore, in S11, if the reactor height is higher than 50 cm, the anaerobic ammonia oxidation filter material and the sulfur autotrophic filter material should be filled alternately. In addition, an external reflux should be set to circulate nitrogen, alkalinity and other substances, and the reflux flow rate / water inlet flow rate should be set at: 0.5-5.

[0033] Further, in S22, the anaerobic ammonium oxidation sludge and the anoxic biochemical sludge are mixed in a volume ratio of 1:4-6, and the MLSS after mixing is: 3000-5000 mg / L. The inoculated sludge should be mixed evenly with the filter material and then filled into the reactor. Further, a fender or a three-phase separator can be set in the clarification area at the top of the reactor to reduce the sludge loss in the initial stage.

[0034] Furthermore, in S33, nitrite nitrogen can be provided by a pre-short-cut nitrification or short-cut denitrification unit, or can be directly added.

[0035] Furthermore, in S33, the influent also includes 100 mg / L of CaCl 2 , 200 mg / L MgSO 4 , 200 mg / L NaHCO 3 and 1.5 mL / L of trace element solution (in g / L, including 1:12 EDTA-2Na, 10FeSO4 7H 2 O, 0.15CuSO 4 ·5H 2 O,0.4ZnSO 4 7H 2 O,0.21CoCl 2 6H 2 O,0.17NiCl 2 6H 2 O,0.99MnCl 2 ·4H 2 O,0.25Na 2 MoO 4 ·2H 2 O,0.019H 3 BO 3 ).

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) A1 filter media has good compressive strength and can support higher filling heights, which is suitable for higher fixed beds in practice. At the same time, the spherical filter media ensures uniform distribution and circulation of water flow, reduces the requirements for reactor materials and structures, and reduces the energy consumption of backwashing.

[0038] (2) The loaded A1-A and A1-S retain the internal foaming and porous surface structural characteristics of A1, and load small particles of minerals on the outer layer. The surface pores can provide an ecological niche for clustered anaerobic ammonia-oxidizing bacteria, and the mineral particles on the surface make the surface of the filter material rougher, which is conducive to the formation of biofilm.

[0039] (3) The surface of A1-A is composed of mineral particles sintered from dolomite, siderite, and blue iron ore powder, which can slowly release Fe 2+ , Ca 2+ Mg 2+ ,PO 4 2- Substances such as gypsum powder and graphite powder contribute to microbial metabolism and EPS secretion, and promote the formation of anaerobic ammonium oxidation biofilm. The outer shell of A1-S is made by the reaction of gypsum powder, graphite powder and a small amount of pyrite particles under anaerobic conditions, which can provide a suitable reducing electron donor for sulfur autotrophy and is suitable for the enrichment of sulfur autotrophic microorganisms. In addition, the shell of A1-S will hardly dissolve in water to inhibit anaerobic ammonium oxidation.

[0040] (4) The coupling of anaerobic ammonium oxidation and sulfur autotrophic can not only achieve nearly 100% autotrophic nitrogen removal effect, but also form alkalinity complementarity, saving the amount of alkalinity added.

[0041] (5) On the one hand, A1-A and A1-S achieved directional enrichment of different functional bacterial genera; on the other hand, anaerobic ammonium oxidizing bacteria tended to aggregate and grow at the bottom of the reactor. The layered arrangement of A1-A and A1-S effectively separated the ecological niches of anaerobic ammonium oxidizing bacteria from sulfur autotrophic bacteria, thus avoiding the vicious competition of sulfur autotrophic bacteria on anaerobic ammonium oxidizing bacteria.

[0042] (6) The present invention achieves the detoxification of waste crocidolite and the resource utilization of various solid wastes, providing an effective strategy for treating waste with waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the SEM image of the internal structure of the A1 filter material;

[0044] Figure 2 This is the SEM image of the surface structure of A1 filter material;

[0045] Figure 3 This is the SEM image of the surface morphology of the anaerobic ammonium oxidation filter material A1-A;

[0046] Figure 4 This is the nitrogen concentration diagram of the inlet and outlet water of the long-term operation of the anaerobic ammonium oxidation-sulfur autotrophic composite filter bed;

[0047] Figure 5 This is a diagram of the denitrification effect of the anaerobic ammonium oxidation-sulfur autotrophic composite filter bed;

[0048] Figure 6 This is a graph showing the extracellular polymer content of the microbial community on the filter media after the anaerobic ammonium oxidation-sulfur autotrophic composite filter bed has been running for a period of time;

[0049] Figure 7 This is the genus-level microbial community diagram in A1-A and A1-S after the anaerobic ammonium oxidation-sulfur autotrophic composite filter bed has been running for a period of time. DETAILED DESCRIPTION

[0050] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0052] Embodiment 1:

[0053] This embodiment provides a method for preparing a foamed porous supported anaerobic ammonium oxidation-sulfur autotrophic composite filter material, comprising the following steps:

[0054] (1) Waste crocidolite (SiO 2 :49.5%,MgO:33%,Fe 2 O 3 : 5.3%, Al 2 O 3 :3.5%, CaO: 2.7%, NiO: 2%, Na 2 O: 2%, K 2 O: 1%) and Bayer red mud (main component: Fe 2 O 3 : 38.5%, Al 2 O 3 : 24.2%, SiO 2 : 19.6%, Na 2 O: 10.1%, CaO: 5.6%, TiO 2 :2%) as the main raw material, mixed in a mass percentage of 4:1, crushed, and passed through a 300-mesh sieve using a standard vibration sieve machine.

[0055] (2) Mixed powder of asbestos red mud, sodium tetraborate cryolite powder, fermented biomass (prepared by compost fermentation, composting experiment was carried out in a sorting box, crushed and sieved pre-treated wood chips were used as auxiliary materials, and other domestic waste (egg shells, oyster shells, coconut shells) were used as raw materials. The ratio was adjusted so that the final C / N was 35 and the moisture content was 40%. The process was carried out for 40 days, with the pile turned over once every 3 days in the first two weeks and once a week thereafter) and water were added into a mixer in a mass percentage of 50%:10%:5%:35% and mixed evenly. Then, a zirconia bead mill was used for wet grinding. The grinding balls and the materials were added in a mass ratio of 1:1. The slurry was obtained after bead milling for 10 hours.

[0056] (3) The slurry is placed in a ceramic container, and then dried at 110°C for 4 hours, and then placed in a mold for compaction, granulation (particle size 2-5 cm), and finally placed in a high-temperature sintering furnace, the sintering temperature is set to 910°C, the heating rate is 10°C / min, and the temperature is kept for 30 minutes after reaching the set temperature. After cooling, a foamed porous spherical filter material is obtained, which is taken out for use and recorded as A1.

[0057] (4) Dolomite, siderite and blue iron ore powders were mixed in a mass ratio of 12:8:3, and then added to an equal volume of 0.3‰ CPAM aqueous solution and stirred for 2 h to obtain an attachment liquid. The attachment liquid was then evenly sprayed three times on the surface of A1 using an electrostatic spray adhesion technique. Finally, the anaerobic ammonia oxidation filter material A1-A was obtained by firing in a muffle furnace at a temperature of 550°C and a time of 60 min.

[0058] (5) Gypsum, graphite, and pyrite powders were mixed in a mass ratio of 8:17:4, and then added to an equal volume of 0.3‰ CPAM aqueous solution and stirred for 1 h. The mixture was then ultrasonically mixed for 1 h to obtain an adhesion liquid. The adhesion liquid was then evenly sprayed three times on the surface of A1 using an electrostatic spray adhesion technique. Finally, a tubular furnace was used to heat the mixture under N 2 The calcination was carried out under the atmosphere, the temperature was set to 550°C, the time was set to 60 minutes, and the sulfur autotrophic filter material A1-S was obtained after the calcination was completed.

[0059] Comparative Example 1:

[0060] Prepare conventional filter materials according to literature reports (Xiao Hongkai, Gong Ting, Zhao Xin, et al. Application research status of red mud-based foamed ceramics [J]. Journal of Hubei Institute of Technology, 2020, 36(02): 39-43.):

[0061] The filter material matrix was prepared with 10g red mud as the main raw material, 1g CaO and 1g MgO were added as flux, and 0.05g SiC was added as foaming agent. After mixing, grinding and drying, the mixture was compacted and granulated, and then placed in a mold for calcination. The sintering temperature was 1100℃, the heating rate was 10℃ / min, and the temperature was kept for 30min after reaching the set temperature. After cooling, a spherical filter material matrix was obtained.

[0062] Comparative Example 2:

[0063] The filter material matrix is ​​prepared with red mud, waste glass and waste porcelain as the main raw materials. Red mud, waste glass and waste porcelain are mixed in a mass ratio of 1:1:1, and 0.5wt% of traditional SiC foaming agent is added. After mixing, grinding and drying, compaction and granulation are performed, and then placed in a mold for calcination. The sintering temperature is 1200℃, the heating rate is 10℃ / min, and the temperature is kept for 30min after reaching the set temperature. After cooling, a spherical filter material matrix is ​​obtained.

[0064] Experimental Example 1: Structural characteristics and physical properties of filter materials

[0065] Figure 1 , Figure 2 This is a picture of the internal and surface structure of the A1 filter material prepared in Example 1. It can be seen that after high-temperature sintering and chemical foaming, a sufficient pore structure is formed inside and on the surface of the filter material.

[0066] Figure 3 This is a SEM image of the surface of the anaerobic ammonium oxidation filter material A1-A. It can be observed that mineral particles are successfully attached to the surface of A1 through electrostatic adhesion technology. In addition, no harmful asbestos fibers originally contained in the raw material crocidolite are observed in the microstructure image, which shows that this method effectively achieves the detoxification of asbestos and realizes the resource utilization of waste.

[0067] The apparent density of A1 measured by Archimedes drainage method is: 677kg / m 3 According to GB T 5486-2008 Test Methods for Inorganic Rigid Insulation Products, the compressive strength is 17.64MPa. At the same time, the physical properties of A1-A and A1-S are similar to those of A1.

[0068] In addition, it can be seen from Table 1 that, compared with Comparative Examples 1 and 2, the raw material composition, flux, and foaming agent in Example 1 make the filter material matrix density more moderate and the compressive strength better. In addition, the appropriate raw material components and flux also reduce the sintering temperature and save the preparation cost.

[0069] Table 1 Test results of filter material matrix prepared in Comparative Examples 1, 2 and Example 1

[0070] Group Sintering time min <![CDATA[Apparent density kg / m 3 > Compressive strengthMpa Comparative Example 1 110 1431 10.1 Comparative Example 2 120 349 7.6 A1 of Example 1 91 677 17.64

[0071] Experimental Example 2: Construction and Operation Evaluation of Anaerobic Ammonium Oxidation-Sulfur Autotrophic Composite Filter Bed (Upflow Filter Bed)

[0072] (1) Anaerobic ammonium oxidation filter media (A1-A) and sulfur autotrophic filter media (A1-S) were used to build a packed fixed bed. The anaerobic ammonium oxidation filter media was placed at the bottom layer. The filter media was filled according to the volume ratio of A1-A: A1-S = 4:1, and the total filling rate was 70%. After filling, the effective volume of the reactor was about 10L, the effective height was 100cm, and a total of 4 layers of filter media were filled. The bottom layer was the A1-A anaerobic ammonium oxidation layer, and the top layer was the A1-S sulfur autotrophic denitrification layer. The influent flow rate (effective volume / hydraulic retention time) was adjusted according to the hydraulic retention time at different stages. Before water inlet, N 2 The synthetic wastewater was purged for 25 minutes to remove dissolved oxygen in the influent. At the same time, a heating rod was used to keep the reactor at 30°C to promote the growth of anaerobic ammonium-oxidizing microorganisms. A sedimentation tank was set at the end of the outlet pipe for sludge return 20 days before the reactor was put into operation.

[0073] (2) Anaerobic ammonium oxidation sludge and anoxic biochemical sludge (acclimatized and stored in the laboratory, initially inoculated in the biochemical section of the sewage treatment plant) that had been stored in the laboratory for 3 months were inoculated. The two sludges were mixed in a volume ratio of 1:5, and the MLSS after mixing was 4000 mg / L.

[0074] (3) The reactor uses wastewater synthesized from ammonium chloride and sodium nitrite, and the influent NO 2 - -N / NH 4 + -N=1-1.3, in addition, the influent also contains 100mg / L CaCl 2 , 200 mg / L MgSO 4 , 200 mg / L NaHCO 3 and 1.5 mL / L of trace element solution (in g / L, including: 12 EDTA-2 Na, 10 FeSO 4 7H 2 O, 0.15CuSO 4 ·5H 2 O,0.4ZnSO 4 7H 2 O,0.21CoCl 2 6H 2 O,0.17NiCl 2 6H 2 O,0.99MnCl 2 ·4H 2 O,0.25Na 2 MoO 4 ·2H 2 O,0.019H 3 BO 3 ).

[0075] (4) Denitrification performance

[0076] The upflow filter bed was operated for 121 days. According to the operation of the reactor, the experimental period was divided into two periods, including the startup phase and the load increase phase. In the startup phase, the reflow ratio was adjusted to screen suitable sludge and retain microorganisms. In the load increase phase, the nitrogen load rate was gradually increased by shortening the HRT and changing the influent substrate concentration. The specific operating conditions are shown in Table 2.

[0077] Table 2 Reactor (upflow filter bed) operating conditions

[0078]

[0079] The removal of pollutants from the reactor's inlet and outlet water is as follows: Figure 4 , Figure 5 As shown in the figure. In the early stage of the startup phase, the larger reflow ratio produces sufficient upward flow velocity, which helps to evenly distribute the microorganisms on the filter bed carrier, and also causes some sludge loss. By gradually reducing the reflow ratio, the functional microorganisms are gradually retained in the system, and the denitrification efficiency is gradually improved.

[0080] In the load increase stage, the HRT is gradually reduced. As the influent nitrogen load rate increases, the denitrification performance is gradually optimized. Studies have shown that anaerobic ammonia oxidation can show higher denitrification efficiency under high load conditions (Shi Haoqian. Denitrification efficiency of anaerobic ammonia oxidation expanded granular sludge bed and spatial response of microbial community structure [D]. Nanjing University of Information Science and Technology, 2024.), but the difference is that in this embodiment, the influent nitrite nitrogen concentration is gradually reduced in the load increase stage, the ammonia nitrogen influent concentration is increased, and the influent matrix ratio is adjusted to make Inf.NH 4 + -N / Inf.NO 2 - -N gradually decreased from 1.3 to about 1. From the experiment, it can be observed that excess nitrite nitrogen gradually appeared in the effluent, which may be converted from part of the sulfur autotrophic denitrification process.

[0081] Theoretically, the anaerobic ammonium oxidation reaction will produce 11% nitrate nitrogen, but due to the coupling of the sulfur autotrophic module, no nitrate accumulation occurred in the effluent. In addition, no S 2- The anaerobic ammonium oxidation inhibition caused by this showed that anaerobic ammonium oxidation and sulfur autotrophy had a synergistic denitrification effect, making the denitrification rate as high as 98% and the ammonia nitrogen removal rate as high as 99%.

[0082] (5) Changes in extracellular polymers and analysis of microbial community diversity

[0083] The A1-A filter media with attached microorganisms was extracted from the bottom of the reactor (15 cm from the water inlet) at 15 days, 40 days, 55 days, 85 days and 120 days respectively. The loose biofilm on the surface was first rinsed with distilled water to collect the sludge turbidity after rinsing. The filter media was then placed in a beaker and ultrasonicated for 30 minutes, and then the sludge suspension was collected after rinsing. Finally, the collected sludge turbidity was centrifuged at 3000 rpm for 5 minutes to collect the biological samples in the centrifuge tube, and the content of extracellular polymers was determined and its components were evaluated. The results are shown in Figure 2. Figure 6 As shown in the figure, from the content and composition of EPS, it can be seen that the biofilm on the filter material is gradually formed, and the biomass gradually increases as the experiment progresses. The biofilm thickness does not gradually decline after reaching a certain degree. This may be due to the porous structure of the filter material. The biofilm gradually grows from the surface to the inside. From the composition point of view, the protein content gradually increases, indicating that the hydrophobicity of the biofilm is enhanced and gradually compacted.

[0084] On the 121st day, the carrier was taken from the anaerobic ammonia oxidation zone and sulfur autotrophic zone in the lower layer of the filter bed, and microbial samples were extracted. Then, high-throughput sequencing was performed together with the preserved inoculum sludge, and statistical analysis of the microbial community diversity at the genus level was performed. Figure 7As shown: the top ten dominant genera in terms of relative abundance are basically the same. Compared with the inoculated sludge, A1-A and A1-S showed better community richness and diversity after the cultivation, which is consistent with the improvement of the system's nitrogen removal efficiency and the growth of biomass.

[0085] Specifically, targeted enrichment of the anaerobic ammonium oxidizer Candidatus_Brocadia and the sulfur oxidizer Thiobacillus was achieved on A1-A and A1-S, respectively, which indicated the mutual separation of functional microorganisms and avoided the competition problem between sulfur autotrophs and anaerobic ammonium oxidizers in a single system.

[0086] (6) A control group reactor (referred to as the control group) was built by mixing a commercially available ceramsite carrier (biological filter material purchased from Runtao Environmental Protection) with a traditional sulfur autotrophic filter material (sulfur powder) to investigate the denitrification of the reactor. Example 1 was referred to as the experimental group. Except for the different reactor carriers, the other operating conditions of the control group were the same as those of the experimental group. The denitrification performance of the two reactors was compared.

[0087] As shown in Table 3, under the same operating conditions and inoculated sludge, the denitrification rate of the experimental group was higher than that of the control group in almost every stage. In the middle and late stages of the startup phase, the denitrification performance of the reactor in the experimental group increased rapidly, which was mainly due to the small particles attached to the surface of the filter material through electrostatic adhesion technology. On the one hand, they promoted the aggregation of microbial organisms and accelerated the formation of biofilms. On the other hand, their dissolutions could act as redox mediators to promote electron transfer and EPS secretion. However, the control group was unable to form an effective anaerobic ammonium oxidation biofilm during the startup phase, resulting in further loss of functional microorganisms due to hydraulic scouring during the load increase phase, which resulted in the inability to effectively improve the denitrification rate, and even decreased.

[0088] At the same time, compared with the control group, the different functional filter materials in the experimental group provided ecological niches for anaerobic ammonia oxidation and sulfur autotrophic microorganisms, respectively, and achieved the directional colonization of functional bacteria. Previous studies (Chen Jie. Research on the effect of scrap iron on alleviating the inhibition of sulfide on anaerobic ammonia oxidation denitrification performance [D]. Suzhou University of Science and Technology, 2023.) have shown that anaerobic ammonia oxidizing bacteria are at a disadvantage in competing with sulfur autotrophic bacteria for nitrite, so the method for preparing microbial filter materials and regional filling of the present invention fundamentally prevent the occurrence of vicious competition, making the anaerobic ammonia oxidizing population dominant in the system.

[0089] Table 3 Comparison of denitrification performance between the experimental group and the control group

[0090]

[0091]

[0092] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.

Claims

1. A method for preparing a foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter material, characterized in that: The following steps are involved: S1. Using waste crocidolite and Bayer red mud as main raw materials, sodium tetraborate and cryolite powder as flux, and fermented waste biomass as foaming agent, the main raw materials, flux and foaming agent are mixed in water, and then wet-grinded to obtain slurry; S2, compacting and granulating the slurry described in S1, and then firing to obtain a foamed porous spherical filter material A1; S3, mixing dolomite, siderite, blue iron ore powder with CPAM aqueous solution to prepare an attachment liquid, and then using electrostatic spray adhesion technology to wrap the attachment liquid on the surface of A1, and after firing, obtain the anaerobic ammonia oxidation filter material A1-A; S4. Gypsum, graphite, pyrite powder and CPAM aqueous solution are mixed to prepare an attachment liquid, and the attachment liquid is coated on the surface of A1 by electrostatic spray adhesion technology. After oxygen-free high-temperature calcination, sulfur autotrophic filter material A1-S is obtained.

2. The method for preparing a foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter material according to claim 1, characterized in that: Calculated by mass percentage, the main components of the waste crocidolite include: SiO2: 45-55%, MgO: 28-33%, Fe2O3: 4-7%, Al2O3: 2-6%, CaO: 1-5%, NiO: 1-3%, Na2O: 1-2%, K2O: 1-2%; calculated by mass percentage, the main components of the Bayer process red mud include: Fe2O3: 35-40%, Al2O3: 20-25%, SiO2: 18-23%, Na2O: 8-12%, CaO: 3-7%, TiO2: 1-4%.

3. The method for preparing a foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter material according to claim 1, characterized in that: In S1, the main raw material, flux, foaming agent and water are uniformly mixed in a mass percentage of 40-55%: 10-15%: 4-6%: 30-40%, and then wet-grinded using a zirconia bead mill to obtain a slurry; among the main raw materials, the waste crocidolite and Bayer process red mud are mixed in a mass ratio of 2-4:1; among the flux, the sodium tetraborate and cryolite powder are mixed in a mass ratio of 2:

1.

4. The method for preparing a foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter material according to claim 1, characterized in that: The firing temperature in S2 is 900-1000°C, the heating rate is 8-12°C / min, and the holding time is 20-40min.

5. The method for preparing a foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter material according to claim 1, characterized in that: In S3, dolomite, siderite and blue iron ore powders are mixed in a mass ratio of 12-18:7-10:1-3, and then added into a 0.3‰ CPAM aqueous solution to prepare an attachment liquid, wherein the molecular weight of the CPAM is between 8 million and 12 million.

6. The method for preparing a foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter material according to claim 1, characterized in that: In S4, gypsum, graphite and pyrite powder are mixed in a mass ratio of 5-11:13-27:3-7, and then added into a 0.3‰ CPAM aqueous solution to prepare an attachment liquid, wherein the molecular weight of the CPAM is between 8 million and 12 million.

7. The method for preparing a foamed porous core-shell anaerobic ammonium oxidation-sulfur autotrophic composite filter material according to claim 1, characterized in that: S3 is fired in a muffle furnace with the temperature set at 500-600°C for 50-70 min; S4 is calcined in a tubular furnace under N2 atmosphere with the temperature set at 500-600°C for 50-70 min.

8. The foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter materials A1-A and A1-S prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the foamed porous core-shell anaerobic ammonia oxidation-sulfur autotrophic composite filter materials A1-A and A1-S according to claim 8 in treating sludge, characterized in that: The sludge includes anaerobic ammonium oxidation sludge and anoxic biochemical sludge.

10. The use according to claim 9, characterized in that: The specific application method includes the following steps: S11, using filter media A1-A and A1-S to build a packed fixed bed, placing A1-A at the bottom, filling the filter media at a volume ratio of A1-A:A1-S=3-5:1, with a total filling rate of 60% to 80%, and the remaining volume is set as a sedimentation and clarification area; S22, inoculated with anaerobic ammonium oxidation sludge and anoxic biochemical sludge, the MLSS of the two sludges after mixing is: 3000-5000mg / L; S33, the reactor uses ammonia and nitrite mixed wastewater, and the inlet NO2 - -N / NH4 + -N=1-1.3.

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