Slow-release anti-poison type sulfur autotrophic denitrification filler, preparation method and application thereof

Abstract

The application relates to a slow-release anti-toxic sulfur autotrophic denitrification filler as well as a preparation method and application thereof. The filler comprises a core, a shell and a biofilm; the core is made of a sulfur source and cationic starch; the raw materials of the core include 3-5 parts of cationic starch and 60-95 parts of the sulfur source in terms of weight fraction; the particle size of the core is 5-7 mm; the shell is coated on the outer surface of the core; the shell includes 3-5 parts of graphene in terms of weight fraction; the thickness of the shell is 1-2 mm; the biofilm is arranged on the outer surface of the shell; the biofilm is composed of a bacterial flora; the quantity of the bacterial flora of the biofilm is greater than 10 8 CFU. The technical problem to be solved is how to provide the slow-release anti-toxic sulfur autotrophic denitrification filler, which can effectively prevent the conversion of thiocyanate into cyanide with biological toxicity and avoid the inhibition of the activity of microorganisms on the surface layer of the filler.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and in particular relates to a slow-release, anti-toxic sulfur autotrophic denitrification packing material, its preparation method, and its application. Background Technology

[0002] Coal-to-oil wastewater is characterized by high total nitrogen concentration (200–500 mg / L), low carbon-to-nitrogen ratio (C / N < 2), and contains toxic substances such as thiocyanates. Given these characteristics, sulfur autotrophic denitrification is considered suitable for treating this type of wastewater. However, in practical applications, this technology still faces many challenges.

[0003] Thiocyanate (SCN-) in wastewater is highly chemically reactive and readily reacts to form cyanide. Cyanide is extremely toxic and significantly inhibits microbial activity, impairing their metabolic functions. In sulfur autotrophic denitrification systems, microorganisms attached to the packing surface form biofilms. While these biofilms reduce direct contact with wastewater to some extent and mitigate the impact of toxic substances on microorganisms, this mitigation is limited and cannot fundamentally eliminate the toxicity of these substances. Ultimately, this still leads to reduced microbial activity and affects nitrogen removal efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide a slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material, its preparation method, and its application. The technical problem to be solved is how to provide a slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material that can effectively prevent the conversion of thiocyanate into biotoxic cyanide and avoid inhibiting the activity of microorganisms on the surface of the packing material.

[0005] The objective of this invention and the technical problem it solves are achieved by the following technical solution. A slow-release, anti-toxic sulfur autotrophic denitrification packing material according to this invention comprises a core, a shell, and a biofilm;

[0006] The core is made of a sulfur source and cationic starch; by weight, the raw materials of the core include: 3-5 parts cationic starch and 60-95 parts sulfur source; the particle size of the core is 5-7 mm.

[0007] The outer shell covers the outer surface of the core; by weight, the outer shell comprises 3-5 parts of graphene; the thickness of the outer shell is 1-2 mm;

[0008] The biofilm is disposed on the outer surface of the shell; the biofilm is composed of a microbial community; the number of microbial communities in the biofilm is greater than 10. 8 CFU.

[0009] Preferably, in the aforementioned slow-release, anti-toxic sulfur autotrophic denitrification packing, the sulfur source is a mixture of elemental sulfur and water-soluble sulfur source.

[0010] Preferably, in the aforementioned slow-release, anti-toxic sulfur autotrophic denitrification packing, the water-soluble sulfur source is sodium thiosulfate; by weight, the sulfur source comprises: 50-70 parts of elemental sulfur and 10-25 parts of sodium thiosulfate.

[0011] Preferably, in the aforementioned slow-release, anti-toxic sulfur autotrophic denitrification packing material, the bacterial community is selected from any one of the genera *Thiobacillus denitrifyingus*, *Pseudomonas denitrifyingus*, and *Thiobacillus*.

[0012] Preferably, in the aforementioned slow-release, anti-toxic, sulfur-autotrophic denitrification packing, the core further comprises 6-15 parts by weight of binder; and the outer shell further comprises 5-8 parts by weight of binder.

[0013] Preferably, in the aforementioned slow-release, anti-toxic, sulfur-autotrophic denitrification packing, the binder is sodium alginate; the concentration of sodium alginate is 1-30%.

[0014] The objective of this invention and the technical problem it solves are further achieved by the following technical solution. A method for preparing a slow-release, anti-toxic sulfur autotrophic denitrification packing material according to this invention includes:

[0015] 1) Kernel preparation:

[0016] Mix 50-70 parts of sulfur source, 10-20 parts of cationic starch and 6-15 parts of binder, granulate, and then dry at 45-55℃ to obtain the core; the particle size of the core is 5-7 mm.

[0017] 2) Preparation of the outer shell:

[0018] Mix 3-5 parts of graphene and 5-8 parts of binder, then spray the mixture onto the outer surface of the core, and then dry and harden it at 105°C; the thickness of the outer shell is 1-2 mm.

[0019] 3) Preparation of biofilms:

[0020] After completing step 2), a bacterial solution is sprayed onto the surface of the outer shell and then cured at room temperature to obtain the product; the number of bacteria on the biofilm is greater than 10. 8 CFU.

[0021] Preferably, in the aforementioned preparation method, the sulfur source includes elemental sulfur and a water-soluble sulfur source; the water-soluble sulfur source is sodium thiosulfate; the elemental sulfur has a mesh size of 500-800 mesh; and the sodium thiosulfate has a mesh size of 150-300 mesh.

[0022] Preferably, in the aforementioned preparation method, the binder is sodium alginate with a concentration of 1-30%; the bacterial solution is selected from any one of the genera *Thiobacillus denitrifyingus*, *Pseudomonas denitrifyingus*, and *Thiobacillus*.

[0023] The objective of this invention and the technical problem it solves are also achieved by the following technical solution. According to this invention, a sulfur autotrophic denitrification fixed bed is provided, the fixed bed comprising packing material; the packing material is the packing material described above.

[0024] By employing the above technical solution, the slow-release, anti-toxic sulfur autotrophic denitrification packing material, its preparation method, and its application proposed in this invention have at least the following advantages:

[0025] This invention constructs a graphene-cationic starch synergistic system, using a component containing cationic starch as the core and a graphene framework as the outer shell to encapsulate the core, forming a composite carrier with a "core-shell" structure. Cationic starch plays a major role in this system. As a modified polymer material, cationic starch possesses a stable positive charge on its surface due to the quaternary ammonium salt groups introduced into its molecular chain. This substance, along with the graphene-based framework material, forms a composite filler system with a three-dimensional porous structure through physical encapsulation. In wastewater treatment, the graphene framework, acting as a rigid support structure, effectively prevents the cationic starch from swelling and deforming during long-term operation. Meanwhile, the positive charge field on the surface of the cationic starch selectively captures thiocyanate ions (SCN-) in the wastewater through electrostatic adsorption, thereby directly reducing the concentration of thiocyanate in the aqueous phase, preventing the reaction of thiocyanate to form cyanide and causing biotoxicity, and avoiding the inhibition of microbial activity on the biofilm.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the packing structure according to an embodiment of the present invention.

[0028] Among them, 1. Core, 2. Shell, 3. Biomembrane. Detailed Implementation

[0029] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation methods, structures, features, and effects of a slow-release, anti-toxic, sulfur-autotrophic denitrification packing material, its preparation method, and its application according to the present invention. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0030] like Figure 1 As shown, the present invention proposes a slow-release, anti-toxic sulfur autotrophic denitrification packing material, which includes a core 1, an outer shell 2, and a biofilm 3;

[0031] The core 1 is made of a sulfur source and cationic starch; by weight, the raw materials of the core include: 3-5 parts cationic starch and 60-95 parts sulfur source; the particle size of the core is 5-7 mm.

[0032] This invention incorporates cationic starch into the core material, primarily to effectively mitigate the inhibitory effect of toxic substances in wastewater on microbial activity. As a macromolecule, cationic starch's positive charge allows it to efficiently adsorb toxic ions—thiocyanate ions (SCN-)—from wastewater, significantly reducing the concentration of thiocyanate. This process effectively blocks the pathway for thiocyanate to further react and form highly toxic cyanides, thus preventing the inhibition of microbial activity on the packing surface due to toxic substances.

[0033] The present invention sets the core particle size to 5-7 mm. This particle size is moderate, which is conducive to its stable existence in the system and can ensure sufficient contact with the surrounding substances to promote the reaction.

[0034] The outer shell 2 covers the outer surface of the core; by weight, the outer shell comprises: 3-5 parts of graphene; the thickness of the outer shell 2 is 1-2 mm;

[0035] This invention selects graphene as the shell of the filler, which has an ultra-large specific surface area and a honeycomb layer structure. When used as a framework, it can significantly improve the dispersion of sulfur, allowing sulfur molecules to be efficiently adsorbed onto its surface and released stably and slowly through π-π stacking. This characteristic not only effectively extends the denitrification reaction cycle but also avoids the problem of filler plate pore blockage caused by excessively rapid release of elemental sulfur, ensuring the long-term stable operation of the reaction system. Furthermore, graphene also has high electrical conductivity, with a resistivity as low as 10⁻⁶. -6 Ω·cm can promote the electron transfer process of sulfur-oxidizing bacteria, thereby indirectly improving the utilization rate of sulfur and providing a strong guarantee for the efficient denitrification reaction.

[0036] The biofilm 3 is disposed on the outer surface of the shell; the biofilm is composed of a microbial community; the number of microbial communities in the biofilm is greater than 10. 8 CFU.

[0037] This invention provides a biofilm on the outer surface of the outer shell, which is composed of a bacterial community with a bacterial count greater than 10. 8 CFU. A sufficient number of microorganisms ensures that the biofilm has high biological activity, effectively carrying out sulfur autotrophic denitrification reactions and improving nitrogen removal efficiency.

[0038] The particle size of the filler disclosed in this invention is 6-10 mm, because the thickness of the biofilm is so low that it can be ignored.

[0039] Preferably, in the aforementioned slow-release, anti-toxic sulfur autotrophic denitrification packing, the sulfur source is a mixture of elemental sulfur and water-soluble sulfur source.

[0040] This invention selects elemental sulfur and sodium thiosulfate as sulfur sources. Sodium thiosulfate, as a water-soluble sulfur source, can rapidly dissolve and release some sulfur source when the packing is introduced into the reaction system, compared to the traditional method of using only elemental sulfur. This allows the sulfur autotrophic denitrification system to obtain sufficient reactants in a short time, thereby accelerating the reaction start-up process, effectively shortening the time required for the system to reach a stable operating state, and improving the overall treatment efficiency.

[0041] Furthermore, during the use of the packing material, sodium thiosulfate gradually leaks out, leaving behind spaces that form unique microporous structures. These microporous structures provide a habitat for microbial attachment and growth, greatly promoting microbial biofilm formation on the packing surface. The increased amount of microbial biofilm effectively enhances the specific surface area of ​​the packing material. A larger specific surface area increases the contact area between reactants and microorganisms, thereby significantly improving mass transfer.

[0042] Preferably, in the aforementioned slow-release, anti-toxic sulfur autotrophic denitrification packing, the water-soluble sulfur source is sodium thiosulfate; by weight, the sulfur source comprises: 50-70 parts of elemental sulfur and 10-25 parts of sodium thiosulfate.

[0043] This invention discloses a sulfur source ratio that can balance the needs of rapid start-up and continuous reaction. It ensures that there is enough sulfur source to be released quickly in the early stage of the system to start the reaction, and can provide a long-term stable sulfur supply through elemental sulfur to maintain the continuous progress of the reaction.

[0044] The sulfur source ratio disclosed in this invention can be dynamically adjusted according to the TN concentration of coal-to-oil wastewater. When the TN concentration of coal-to-oil wastewater is >300mg / L, the proportion of sodium thiosulfate is increased to 25 parts.

[0045] Preferably, in the aforementioned slow-release, anti-toxic sulfur autotrophic denitrification packing material, the bacterial community is selected from any one of the genera *Thiobacillus denitrifyingus*, *Pseudomonas denitrifyingus*, and *Thiobacillus*.

[0046] Preferably, in the aforementioned slow-release, anti-toxic, sulfur-autotrophic denitrification packing, the core further comprises 6-15 parts by weight of binder; and the outer shell further comprises 5-8 parts by weight of binder.

[0047] This invention discloses the addition of binders to both the outer shell and the core. Adding a binder to the core allows the core materials to bond together better, ensuring the structural stability of the core and preventing it from breaking apart during the reaction, which would affect the reaction effect. Adding a binder to the outer shell allows graphene to be uniformly coated on the surface of the core, forming a stable outer shell structure. This ensures that graphene can fully exert its adsorption and conductivity functions, while also enhancing the mechanical strength of the outer shell.

[0048] Preferably, in the aforementioned slow-release, anti-toxic, sulfur-autotrophic denitrification packing, the binder is sodium alginate; the concentration of sodium alginate is 1-30%.

[0049] The binder used in this invention is sodium alginate, which is non-toxic to microorganisms and will not affect the growth and activity of bacteria on the biofilm.

[0050] This invention limits the concentration of sodium alginate to 1-30%, which ensures good adhesion without affecting the performance of other components due to excessive concentration.

[0051] This invention also proposes a method for preparing a slow-release, anti-toxic sulfur autotrophic denitrification packing, the preparation method comprising:

[0052] 1) Kernel preparation:

[0053] Mix 50-70 parts of sulfur source, 10-20 parts of cationic starch and 6-15 parts of binder, granulate, and then dry at 45-55℃ to obtain the core; the particle size of the core is 5-7 mm.

[0054] 2) Preparation of the outer shell:

[0055] Mix 3-5 parts of graphene and 5-8 parts of binder, then spray the mixture onto the outer surface of the core, and then dry and harden it at 105°C.

[0056] 3) Preparation of biofilms:

[0057] After completing step 2), a bacterial solution is sprayed onto the surface of the outer shell and then cured at room temperature to obtain the product; the number of bacteria on the biofilm is greater than 10. 8 CFU.

[0058] Preferably, in the aforementioned preparation method, the sulfur source includes elemental sulfur and a water-soluble sulfur source; the water-soluble sulfur source is sodium thiosulfate; the elemental sulfur has a mesh size of 500-800 mesh; and the sodium thiosulfate has a mesh size of 150-300 mesh.

[0059] The sulfur source used in this invention has a mesh size of 500-800 for elemental sulfur and 150-300 for sodium thiosulfate. Appropriate mesh sizes ensure uniform dispersion of the sulfur source within the core, guaranteeing stable release of sulfur during the reaction. Simultaneously, the combination of different mesh sizes creates a specific porous structure, facilitating material transport and reaction, and improving the efficiency of the denitrification reaction.

[0060] Preferably, in the aforementioned preparation method, the binder is sodium alginate with a concentration of 10%; the bacterial solution is selected from any one of the genera *Thiobacillus denitrifyingus*, *Pseudomonas denitrifyingus*, and *Thiobacillus*.

[0061] The present invention also proposes a sulfur autotrophic denitrification fixed bed, the fixed bed comprising packing material; the packing material is the packing material described above.

[0062] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0063] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0064] Example 1

[0065] A slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material, comprising a core, an outer shell, and a biofilm;

[0066] The raw materials of the core include: 3 parts cationic starch, 50 parts elemental sulfur, 20 parts sodium thiosulfate and 15 parts sodium alginate with a concentration of 10%.

[0067] The raw materials for the outer shell include: 5 parts graphene and 5 parts sodium alginate with a concentration of 10%;

[0068] The biofilm is composed of a group of denitrifying thiobacteria; the number of the biofilm bacterial group is 10. 8 CFU / g.

[0069] Its preparation methods include:

[0070] 1) Prepare materials:

[0071] Elemental sulfur was ground to 800 mesh; sodium thiosulfate was ground to 200 mesh.

[0072] 2) Core preparation:

[0073] A sulfur source, cationic starch, and sodium alginate were mixed, granulated, and then dried at 50°C to obtain the core; the core had a particle size of 7 mm.

[0074] 3) Preparation of the outer shell:

[0075] Graphene and sodium alginate are mixed and then sprayed onto the outer surface of the core, and then dried and hardened at 105°C.

[0076] 4) Preparation of biofilms:

[0077] After completing step 3), a solution of denitrifying thiobacillus is sprayed onto the surface of the outer shell, and then cured at room temperature for 24 hours to obtain the product; the number of bacteria on the biofilm is 10. 8 CFU / g.

[0078] Example 2

[0079] A slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material, comprising a core, an outer shell, and a biofilm;

[0080] The raw materials of the core include: 3 parts cationic starch, 65 parts elemental sulfur, 10 parts sodium thiosulfate and 13 parts sodium alginate with a concentration of 10%.

[0081] The raw materials for the outer shell include: 4 parts graphene and 5 parts sodium alginate with a concentration of 10%;

[0082] The biofilm is composed of a group of denitrifying thiobacteria; the number of the biofilm bacterial group is 10. 8 CFU / g.

[0083] Its preparation methods include:

[0084] 1) Prepare materials:

[0085] Elemental sulfur was ground to 800 mesh; sodium thiosulfate was ground to 200 mesh.

[0086] 2) Core preparation:

[0087] A sulfur source, cationic starch, and sodium alginate were mixed, granulated, and then dried at 50°C to obtain the core; the core had a particle size of 7 mm.

[0088] 3) Preparation of the outer shell:

[0089] Graphene and sodium alginate are mixed and then sprayed onto the outer surface of the core, and then dried and hardened at 105°C.

[0090] 4) Preparation of biofilms:

[0091] After completing step 3), a solution of denitrifying thiobacillus is sprayed onto the surface of the outer shell, and then cured at room temperature for 24 hours to obtain the product; the number of bacteria on the biofilm is 10. 8 CFU / g.

[0092] Example 3

[0093] A slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material, comprising a core, an outer shell, and a biofilm;

[0094] The raw materials of the core include: 3 parts cationic starch, 50 parts elemental sulfur, 10 parts sodium thiosulfate and 6 parts sodium alginate with a concentration of 1%.

[0095] The raw materials for the outer shell include: 3 parts graphene and 5 parts sodium alginate with a concentration of 1%;

[0096] The biofilm is composed of a group of denitrifying thiobacteria; the number of the biofilm bacterial group is 10. 8 CFU / g.

[0097] Its preparation methods include:

[0098] 1) Prepare materials:

[0099] Elemental sulfur was ground to 500 mesh; sodium thiosulfate was ground to 150 mesh.

[0100] 2) Core preparation:

[0101] A sulfur source, cationic starch, and sodium alginate were mixed, granulated, and then dried at 45°C to obtain the core; the core had a particle size of 5 mm.

[0102] 3) Preparation of the outer shell:

[0103] Graphene and sodium alginate are mixed and then sprayed onto the outer surface of the core, and then dried and hardened at 105°C.

[0104] 4) Preparation of biofilms:

[0105] After completing step 3), a solution of denitrifying thiobacillus is sprayed onto the surface of the outer shell, and then cured at room temperature for 24 hours to obtain the product; the number of bacteria on the biofilm is 10. 8 CFU / g.

[0106] Example 4

[0107] A slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material, comprising a core, an outer shell, and a biofilm;

[0108] The raw materials of the core include: 5 parts cationic starch, 70 parts elemental sulfur, 25 parts sodium thiosulfate and 15 parts sodium alginate with a concentration of 30%.

[0109] The raw materials for the outer shell include: 5 parts of graphene and 8 parts of sodium alginate with a concentration of 30%;

[0110] The biofilm is composed of a group of denitrifying thiobacteria; the number of the biofilm bacterial group is 10. 8 CFU / g.

[0111] Its preparation methods include:

[0112] 1) Prepare materials:

[0113] Elemental sulfur was ground to 800 mesh; sodium thiosulfate was ground to 300 mesh.

[0114] 2) Core preparation:

[0115] A sulfur source, cationic starch, and sodium alginate were mixed, granulated, and then dried at 55°C to obtain the core; the core had a particle size of 7 mm.

[0116] 3) Preparation of the outer shell:

[0117] Mix 5 parts graphene and 8 parts sodium alginate, then spray the mixture onto the outer surface of the core, and then dry and harden it at 105°C.

[0118] 4) Preparation of biofilms:

[0119] After completing step 3), a solution of denitrifying thiobacillus is sprayed onto the surface of the outer shell, and then cured at room temperature for 24 hours to obtain the product; the number of bacteria on the biofilm is 10. 8 CFU / g.

[0120] Example 5

[0121] A slow-release, toxic-resistant, sulfur-autotrophic denitrification packing material, comprising a core, an outer shell, and a biofilm;

[0122] The raw materials of the core include: 4 parts cationic starch, 60 parts elemental sulfur, 20 parts sodium thiosulfate and 10 parts sodium alginate with a concentration of 20%.

[0123] The raw materials for the outer shell include: 4 parts graphene and 7 parts sodium alginate with a concentration of 10%;

[0124] The biofilm is composed of a group of denitrifying thiobacteria; the number of the biofilm bacterial group is 10. 8 CFU / g.

[0125] Its preparation methods include:

[0126] 1) Prepare materials:

[0127] Elemental sulfur was ground to 700 mesh; sodium thiosulfate was ground to 200 mesh.

[0128] 2) Core preparation:

[0129] A sulfur source, cationic starch, and sodium alginate were mixed, granulated, and then dried at 50°C to obtain the core; the core had a particle size of 6 mm.

[0130] 3) Preparation of the outer shell:

[0131] Graphene and sodium alginate are mixed and then sprayed onto the outer surface of the core, and then dried and hardened at 105°C.

[0132] 4) Preparation of biofilms:

[0133] After completing step 3), a solution of denitrifying thiobacillus is sprayed onto the surface of the outer shell, and then cured at room temperature for 24 hours to obtain the product; the number of bacteria on the biofilm is 10. 8 CFU / g.

[0134] Example 6

[0135] A sulfur autotrophic denitrification fixed bed is disclosed, using the packing material described in Example 1. The fixed bed has a packing height of 2m, a hydraulic retention time of 8h, and is capable of treating coal-to-oil wastewater with TN = 320mg / L, SCN- = 15mg / L, and pH = 6.0. The treatment effect is shown in Table 1.

[0136] Table 1: Experimental results of treating coal-to-oil wastewater using a sulfur-autotrophic denitrification fixed-bed system as described in Example 6

[0137] <![CDATA[Nitrate (NO3 - )]]> 320mg / L 8.2 mg / L 97.4％ pH fluctuations 6.0-6.5 7.0-7.3 —

[0138] Example 7

[0139] A sulfur autotrophic denitrification fixed bed was described in Example 7, which used the packing material described in Example 2, compared to Example 6. The treatment results are shown in Table 2.

[0140] Table 2: Experimental results of the sulfur autotrophic denitrification fixed bed treatment of coal-to-oil wastewater described in Example 7

[0141] <![CDATA[Nitrate (NO3 - )]]> 150mg / L 5.5 mg / L 96.3％ pH fluctuations 6.0-6.8 7.2-7.5 —

[0142] Comparative Example 1

[0143] Compared to Example 6, Comparative Example 1 did not include graphene and cationic starch. The treatment results are shown in Table 3.

[0144] Table 3: Experimental results of treating coal-to-oil wastewater using a sulfur autotrophic denitrification fixed bed as described in Comparative Example 1

[0145] <![CDATA[Nitrate (NO3 - )]]> 320mg / L 55.04 mg / L 82.8％ pH fluctuations 6.0-6.5 7.0-7.3 —

[0146] Comparative Example 2

[0147] Compared to Example 6, Comparative Example 2 did not include graphene. The treatment results are shown in Table 4.

[0148] Table 4: Experimental results of sulfur autotrophic denitrification fixed bed treatment of coal-to-oil wastewater as described in Comparative Example 2

[0149] <![CDATA[Nitrate (NO3 - )]]> 320mg / L 39.2 mg / L 87.8％ pH fluctuations 6.0-6.5 7.0-7.3 —

[0150] Comparative Example 3

[0151] Compared to Example 6, Comparative Example 3 did not include cationic starch. The treatment results are shown in Table 5.

[0152] Table 5: Experimental results of sulfur autotrophic denitrification fixed bed treatment of coal-to-oil wastewater as described in Comparative Example 3

[0153] <![CDATA[Nitrate (NO3 - )]]> 320mg / L 52.5 mg / L 83.6％ pH fluctuations 6.0-6.5 7.0-7.3 —

[0154] Comparing the experimental results of Example 6 and Comparative Example 1, it can be seen that when using the packing material disclosed in this invention, the nitrate removal rate in Example 6 reached 97.4%, far exceeding the removal rate of Comparative Example 1 (82.8%). This data clearly demonstrates that the graphene-cationic starch synergistic system constructed in this invention has a good effect on removing nitrates from wastewater. The graphene framework acts as a rigid support structure, effectively preventing the cationic starch from swelling and deforming during long-term operation, and allowing the substances in the core to be slowly released, thus preventing large molecules from being released and releasing small molecules. Furthermore, the positive charge field on the surface of the cationic starch selectively captures thiocyanate ions (SCN-) present in the wastewater, thereby directly reducing the concentration of thiocyanate in the aqueous phase, preventing the reaction of thiocyanate to form cyanide and causing biotoxicity, and avoiding the inhibition of microbial activity on the biofilm.

[0155] Comparing the nitrate removal rates of Example 6 with those of Comparative Examples 1-3, the experimental data are shown in Table 6:

[0156] Table 6: Comparison of Experimental Data

[0157]

[0158] The nitrate removal rates of the single-component systems (Comparative Examples 2 and 3) were reduced by 9.6% and 13.8% respectively compared to the optimized composite system (Example 6), while the control group (Comparative Example 1) without any filler showed an even greater reduction of 14.6%. This result clearly demonstrates that:

[0159] The combination of graphene and cationic starch is not a simple superposition, but can form a graphene-cationic starch synergistic system. The core is composed of cationic starch and the outer shell is graphene skeleton to cover the core, forming a composite carrier with a "core-shell" structure, thereby avoiding the inhibition of microbial activity on biofilms.

[0160] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0161] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A slow-release anti-toxic sulfur-autotrophic denitrification packing material, characterized in that, It includes a core, a shell, and a biofilm; the slow-release, anti-toxic sulfur autotrophic denitrification packing is applied to wastewater containing thiocyanate and can reduce the concentration of thiocyanate in the aqueous phase. The core is made of a sulfur source and cationic starch; By weight, the raw materials of the core include: 3-5 parts cationic starch and 60-95 parts sulfur source; the particle size of the core is 5-7 mm. The outer shell covers the outer surface of the core; by weight, the outer shell comprises 3-5 parts of graphene; the thickness of the outer shell is 1-2 mm; The biofilm is disposed on an outer surface of the housing; the biofilm is comprised of a population of bacteria; the population of biofilm bacteria is greater than 10 8 CFU; the population of bacteria is selected from any one of Thiobacillus and Sulfurospirillum.

2. The slow-release, anti-toxic, sulfur-autotrophic denitrification packing material according to claim 1, characterized in that, The sulfur source is a mixture of elemental sulfur and water-soluble sulfur source.

3. The slow-release, anti-toxic, sulfur-autotrophic denitrification packing material according to claim 2, characterized in that, The water-soluble sulfur source is sodium thiosulfate; The sulfur source comprises, by weight, 50-70 parts of elemental sulfur and 10-25 parts of sodium thiosulfate.

4. The slow-release, anti-toxic, sulfur-autotrophic denitrification packing material according to claim 1, characterized in that, The core further comprises 6-15 parts by weight of adhesive; the outer shell further comprises 5-8 parts by weight of adhesive.

5. The slow-release, anti-toxic, sulfur-autotrophic denitrification packing material according to claim 4, characterized in that, The adhesive is sodium alginate; the concentration of sodium alginate is 1-30%.

6. A method for preparing a slow-release, anti-toxic sulfur autotrophic denitrification packing, characterized in that, The preparation method includes: the slow-release anti-toxic sulfur autotrophic denitrification packing is applied to wastewater containing thiocyanate, which can reduce the concentration of thiocyanate in the aqueous phase; 1) Kernel preparation: Mix 60-95 parts of sulfur source, 3-5 parts of cationic starch and 6-15 parts of binder, granulate, and then dry at 45-55℃ to obtain the core; the particle size of the core is 5-7 mm. 2) Preparation of the outer shell: Mix 3-5 parts of graphene and 5-8 parts of binder, then spray the mixture onto the outer surface of the core, and then dry and harden it at 105°C; the thickness of the outer shell is 1-2 mm. 3) Preparation of biofilms: After the execution of step 2), the bacterial solution is sprayed on the surface of the shell, and then solidified at room temperature to obtain the product; the number of the bacterial population on the biofilm is greater than 10 8 CFU; the bacterial population is selected from any one of Thiobacillus and Sulfur Oxidizing Bacteria.

7. The preparation method according to claim 6, characterized in that: The sulfur source includes elemental sulfur and a water-soluble sulfur source; the water-soluble sulfur source is sodium thiosulfate; the elemental sulfur has a mesh size of 500-800 mesh; and the sodium thiosulfate has a mesh size of 150-300 mesh.

8. The preparation method according to claim 7, characterized in that: The adhesive is sodium alginate with a concentration of 1-30%.

9. A sulfur autotrophic denitrification fixed bed, characterized in that, The fixed bed includes packing material; the packing material is the packing material as described in any one of claims 1 to 5.

Images