A kind of zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule and its preparation and application

Abstract

The present invention discloses a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule and its preparation and application, belonging to the field of wastewater treatment technology. The preparation method comprises the following steps: S1. preparing a biochemical mixed embedding solution containing an embedding material and a gelling agent; S2. adding the biochemical mixed embedding solution obtained in step S1 to a cross-linking solution, and performing a cross-linking treatment to obtain the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule; in step S1, the embedding material comprises zero-valent iron, anaerobic digestion bacteria and a carbon source, and the zero-valent iron, anaerobic digestion bacteria and the carbon source are fixed together inside and on the surface of porous particles, effectively preventing the loss of zero-valent iron and anaerobic digestion bacteria, and reducing the generation of zero-valent iron passivation; and the carbon source is embedded in the immobilized particles, effectively realizing the slow release of the carbon source, by achieving a dynamic balance between the carbon source supply and the biological demand.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and more specifically to a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule and its preparation and application. Background Art

[0002] Among the various existing organic wastewater pollution remediation technologies, microbial-based anaerobic digestion technology has become one of the most widely used processes due to its economy, environmental friendliness and process reliability. However, low-biodegradable organic wastewater usually has complex components, high biological toxicity, and contains a large number of complex organic matter that is difficult to be directly degraded by microorganisms. It is necessary to supplement high-quality carbon sources to degrade them in a co-metabolism manner, which leads to large technical barriers and remediation costs for anaerobic digestion technology during the treatment process. At present, the use of zero-valent iron coupled anaerobic digestion bacteria in the remediation process of low-biodegradable organic wastewater has attracted widespread attention. Zero-valent iron can not only quickly improve the biodegradability of wastewater through chemical reduction and physical adsorption, but also act as an electron donor to reduce the demand for high-quality carbon sources. It can also regulate the activity and population structure evolution of anaerobic digestion bacteria, and ultimately enhance the biological treatment performance of low-biodegradable organic wastewater.

[0003] Although the synergistic application of anaerobic digestion bacteria and zero-valent iron can achieve efficient, economical and environmentally friendly treatment of organic wastewater, the following shortcomings still exist: (1) Suspended zero-valent iron and microorganisms are lost during the reaction process, causing economic losses and performance degradation; (2) Zero-valent iron is prone to passivation and agglomeration, resulting in reduced activity and shortened service life; (3) Zero-valent iron has certain biological toxicity, and its dosage must be strictly controlled to avoid negative effects on anaerobic digestion bacteria; (4) The one-time addition of carbon source may not form optimal reaction conditions with microorganisms, resulting in: excess carbon source in the early stage, causing secondary pollution of organic carbon, and can also mask the electron supply of zero-valent iron, restricting the promotion effect of zero-valent iron; insufficient carbon source in the later stage, limited remediation performance; (5) The high-quality carbon sources in the current patents are mostly in liquid form, and the added amount is difficult to dynamically balance with biological needs, which limits the pollution remediation performance of the zero-valent iron-microorganism coupling system. For example, a Chinese patent with publication number CN114455703A discloses a method for treating heavy metal-containing organic wastewater by using biochar-encapsulated zero-valent iron coupled with sulfate reduction. The zero-valent iron is immobilized on biochar and coupled with anaerobic sludge, which significantly improves the growth metabolism of microorganisms and the efficiency of anaerobic digestion. However, the zero-valent iron and microorganisms in the coupling system are still in a suspended state, and the loss problem has not been completely solved. Summary of the invention

[0004] 1. Technical problem to be solved by the invention

[0005] In view of the problem that zero-valent iron, microorganisms and carbon source are easily lost in the synergistic application of anaerobic digestion bacteria and zero-valent iron in the prior art, resulting in poor treatment effect, a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule and a preparation method thereof are provided.

[0006] 2. Technical solution

[0007] In order to achieve the above object, the technical solution provided by the present invention is:

[0008] The method for preparing a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule of the present invention comprises the following steps:

[0009] S1. preparing a biochemical mixed embedding solution containing an embedding material and a gelling agent;

[0010] S2. adding the biochemical mixed embedding solution obtained in step S1 to the cross-linking solution for cross-linking treatment to obtain the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules;

[0011] Wherein, in step S1, the embedding material includes zero-valent iron, anaerobic digestion bacteria and a carbon source;

[0012] The carbon source includes one, two or more of glucose, sodium acetate and sucrose;

[0013] The zero-valent iron includes one or both of nano zero-valent iron and micron zero-valent iron.

[0014] Furthermore, in the biochemical mixed embedding solution, the content of zero-valent iron is 40-80 mM;

[0015] The anaerobic digestion bacteria are added through a bacterial solution containing anaerobic digestion bacteria, and the volume fraction of the bacterial solution containing anaerobic digestion bacteria is 20% to 40.0%;

[0016] The concentration of anaerobic digestion bacteria in the bacterial solution is 10-20 g / L;

[0017] The content of the carbon source is 2-4 g / L.

[0018] Furthermore, in step S1, the gelling agent is one or both of sodium alginate and polyvinyl alcohol.

[0019] Furthermore, the gelling agent is added in the form of an aqueous solution of the gelling agent.

[0020] Furthermore, the aqueous solution of the gelling agent is one or both of a sodium alginate aqueous solution and a polyvinyl alcohol aqueous solution.

[0021] Further, the concentration of sodium alginate in the sodium alginate aqueous solution is 1.0-3.0wt%;

[0022] The concentration of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 5.0-10.0 wt %.

[0023] Furthermore, in step S2, the cross-linking agent is one or both of a calcium chloride solution and a saturated boric acid solution containing calcium chloride.

[0024] Further, the concentration of the calcium chloride solution is 0.5-4.0wt%;

[0025] The concentration of calcium chloride in the saturated boric acid solution containing calcium chloride is 0.5-4.0wt%.

[0026] Furthermore, in step S2, the cross-linking treatment is carried out for 1 to 4 hours at a temperature of 25 to 30°C.

[0027] Furthermore, step S1 may specifically include: adding the embedding material dropwise into the gelling agent to obtain a biochemical mixed embedding solution.

[0028] The present invention also provides a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule prepared by the above preparation method,

[0029] The zero-valent iron-carbon source-anaerobic digestion bacteria slow-release microcapsules include porous particles;

[0030] The porous particles include a porous organic gel and an embedding material embedded in the porous organic gel.

[0031] The embedding material comprises zero-valent iron, anaerobic digestion bacteria and a carbon source.

[0032] Furthermore, the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules are porous particles.

[0033] Furthermore, the porous organic gel is obtained by cross-linking polymerization of a gelling agent.

[0034] The gelling agent is one or both of sodium alginate and polyvinyl alcohol.

[0035] Furthermore, the diameter of the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules is 4-6 mm.

[0036] The present invention also provides a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule prepared by the above preparation method or the use of the above zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule in treating organic wastewater.

[0037] Furthermore, the organic wastewater contains at least one organic substance selected from the group consisting of p-nitrophenol (PNP), sulfamethoxazole, and N,N-dimethylformamide.

[0038] 3. Beneficial effects

[0039] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0040] (1) The method for preparing the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules provided by the present invention fixes the embedded material in the porous organic gel by an embedding and cross-linking embedding method. The embedded material includes zero-valent iron, anaerobic digestion bacteria and a carbon source, which effectively prevents the loss of the carbon source, zero-valent iron and anaerobic digestion bacteria and provides better reaction conditions; it also improves the utilization efficiency of zero-valent iron, reduces the generation of zero-valent iron passivation, and enhances the tolerance of anaerobic digestion bacteria to zero-valent iron and complex environments;

[0041] In addition, the carbon source is embedded in the immobilized particles, which effectively realizes the controlled release of the carbon source and improves the bioavailability of zero-valent iron electrons; it can also prepare sustained-release microcapsules with high mechanical strength, good mass transfer performance and excellent treatment effect.

[0042] (2) The zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules provided by the present invention include porous particles; the porous particles include porous organic gel and an embedding material embedded in the porous organic gel, and zero-valent iron, anaerobic digestion bacteria and high-quality carbon source are fixed inside and on the surface of the porous particles, thereby immobilizing the carbon source, zero-valent iron and anaerobic digestion bacteria, and reducing the loss of zero-valent iron, anaerobic digestion bacteria and high-quality carbon source;

[0043] The zero-valent iron-carbon source-anaerobic digestion bacteria slow-release microcapsules embed fixed zero-valent iron, anaerobic digestion bacteria and high-quality carbon source, providing a better reaction environment and reaction conditions. Organic matter enters through the holes on the microcapsules and is degraded under better conditions, thereby improving the degradation effect.

[0044] (3) The zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules provided by the present invention use highly biocompatible sodium alginate and polyvinyl alcohol as immobilization carriers, which effectively solves the problem of loss of zero-valent iron and microorganisms and improves the environmental tolerance of the zero-valent iron-microorganism coupling system in the process of complex low-biodegradable organic wastewater remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule of the present invention;

[0046] Figure 2 The p-nitrophenol degradation performance diagram of the performance tests in Example 1, Comparative Example 2 and Comparative Example 3 of the present invention.

[0047] Explanation of the symbols in the schematic diagram:

[0048] 100. anaerobic digestion bacteria; 200. zero-valent iron; 300. porous organic gel; 301. pores. DETAILED DESCRIPTION

[0049] The present disclosure may be more easily understood by reference to the following description in conjunction with examples, all of which constitute a part of the present disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described and / or illustrated herein. Further, the terms used herein are only used for the purpose of describing specific embodiments by way of example and are not intended to be limiting unless otherwise indicated.

[0050] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically not included, each separate embodiment is considered to be combinable with any other embodiment, and the combination is considered to represent another different embodiment. Conversely, for the sake of simplicity, the various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or substructure itself may also be considered to be an independent embodiment.

[0051] Unless otherwise indicated, it should be understood that each individual element in a list and each combination of individual elements in the list will be interpreted as a different embodiment. For example, a list of embodiments represented as "A, B, or C" should be interpreted to include embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B, or C".

[0052] In the present disclosure, the singular forms of the articles "a," "an," and "the" also include the corresponding plural references, and a reference to a specific value includes at least that specific value unless the context clearly indicates otherwise. Thus, for example, a reference to "a substance" is a reference to at least one of that substance and equivalents thereof.

[0053] When items are described by using the conjunction terms "... and / or...," etc., the description should be understood to include any one of the associated listed items and all combinations of one or more thereof.

[0054] In general, the use of the term "about" indicates an approximate value that may vary depending on the desired properties obtained by the disclosed subject matter, and will be interpreted in a context-dependent manner based on function. Therefore, one of ordinary skill in the art will be able to interpret a certain degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about". In other cases, a gradient in a range of values ​​can be used to determine the range of differences allowed by the term "about". Further, all ranges in this disclosure are inclusive and combinable, and reference to a value in a range includes each value within that range.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0056] In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be purchased commercially.

[0057] Polyvinyl alcohol is polyvinyl alcohol 124, purchased from Shanghai McLean Biochemical Technology Co., Ltd., model P909857; sodium alginate was purchased from Shanghai McLean Biochemical Technology Co., Ltd., model S817374; calcium chloride was purchased from Shanghai McLean Biochemical Technology Co., Ltd., model C915443.

[0058] The bacterial liquid containing anaerobic digestion bacteria used in the embodiments of the present invention and the comparative examples was obtained by acclimatization and culture in a glucose-based medium (COD=2000 mg / L), wherein the activated sludge was derived from the anaerobic digestion tank in Taixing Industrial Park, Jiangsu Province. The activated sludge was acclimatized and cultured in a plastic barrel at room temperature for 1 month, and the culture medium was renewed every 1 week. The composition of the culture medium was (g / L): C6H 12 O6 (glucose) 0.188 g / L, NH4Cl 0.382 g / L, KH2PO4 0.148 g / L, CaCl2 0.08 g / L, MgSO4·7H2O 0.02 g / L, NaHCO3 2 g / L, pH 7.5±0.2, the concentration of the bacterial solution obtained by acclimation culture is 10g / L. After acclimation, the dominant functional bacterial genera in the anaerobic digestion bacteria are Bacteroides , Clostridium and Methanosaeta .

[0059] It should be noted that the activated sludge acclimation scheme is also applicable to the acclimation process of activated sludge from other sources in anaerobic digesters, such as the anaerobic tank of Beijing Qinghe Wastewater Treatment Plant and the anaerobic digester of Jinmaoyuan Park in Taixing, Jiangsu.

[0060] The present invention is further described below in conjunction with specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The essential characteristics and remarkable effects of the present invention can be reflected from the following examples, and the described embodiments are part of the embodiments of the present invention, rather than all the embodiments, and therefore, they do not limit the present invention in any way, and those skilled in the art make some non-essential improvements and adjustments based on the content of the present invention, which all belong to the protection scope of the present invention.

[0061] Example 1

[0062] This embodiment provides a preparation method for a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule:

[0063] (1) Add 30 mL of 10 g / L anaerobic digestion bacteria solution, 6 mmol of nano-zero-valent iron, and 0.3 g of glucose to 70 mL of 2.0 wt% sodium alginate aqueous solution to obtain a biochemical mixed embedding solution;

[0064] (2) The biochemical mixed embedding solution obtained in step (1) was added dropwise into 500 mL of a 2.0 wt% saturated boric acid solution containing calcium chloride, and cross-linked at 25° C. for 2 h to obtain zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules.

[0065] The particle size of the prepared zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules is 4 mm.

[0066] Performance test: Prepare 1L of water sample with a p-nitrophenol concentration of 100 mg / L, add 20mL of the prepared zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules, and oscillate the reaction at room temperature for 3 days. Take samples every other day to measure the p-nitrophenol concentration in the water sample and calculate the degradation rate.

[0067] The zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules prepared in this example are porous particles. Figure 1As shown, the porous particles include a porous organic gel 300 and an embedding material embedded in the porous organic gel 300, wherein the embedding material is basically zero-valent iron 200, anaerobic digestion bacteria 100 and a high-quality carbon source, wherein the zero-valent iron 200 is nano zero-valent iron, and the carbon source is glucose, which exists in molecular form. The zero-valent iron 200, the anaerobic digestion bacteria 100 and the high-quality carbon source are fixed inside and on the surface of the porous particles, reducing the loss. There are a number of holes 301 on the porous organic gel 300, and organic matter enters through the holes 301 and is degraded under better conditions, which is conducive to improving the degradation effect.

[0068] Example 2

[0069] This embodiment provides a preparation method for a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule:

[0070] (1) Add 40 mL of 10 g / L anaerobic digestion bacteria solution, 8 mmol of nano-zero-valent iron, and 0.4 g of sodium acetate to 60 mL of 5.0 wt% polyvinyl alcohol aqueous solution to obtain a biochemical mixed embedding solution;

[0071] (2) The biochemical mixed embedding solution obtained in step (1) is added dropwise into 500 mL of a 1.0 wt% saturated boric acid solution containing calcium chloride, and cross-linked at 30° C. for 4 h to obtain the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules.

[0072] Example 3

[0073] This embodiment provides a preparation method for a zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule:

[0074] (1) Add 20 mL of 10 g / L anaerobic digestion bacteria solution, 4 mmol micron zero-valent iron, and 0.2 g glucose to 80 mL of 3.0 wt% sodium alginate aqueous solution to obtain a biochemical mixed embedding solution;

[0075] (2) The biochemical mixed embedding solution obtained in step (1) was added dropwise into 500 mL of 1.0 wt% calcium chloride solution, and cross-linked for 1 h at 25° C. to obtain the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules.

[0076] Comparative Example 1

[0077] This comparative example provides a preparation method for zero-valent iron-carbon source sustained-release microcapsules:

[0078] (1) Add 30 mL of deionized water, 6 mmol of nano-zero-valent iron, and 0.3 g of glucose to 70 mL of 2.0 wt% sodium alginate aqueous solution to obtain a mixed embedding solution;

[0079] (2) The mixed embedding solution obtained in step (1) was added dropwise into 500 mL of a 2.0 wt% saturated boric acid solution containing calcium chloride, and cross-linked at 25° C. for 2 h to obtain the zero-valent iron-carbon source sustained-release microcapsules.

[0080] Comparative Example 2

[0081] This comparative example provides a preparation method for zero-valent iron sustained-release microcapsules:

[0082] (1) Add 30 mL of deionized water and 6 mmol of nano-zero-valent iron into 70 mL of 2.0 wt% sodium alginate aqueous solution to obtain a mixed embedding solution;

[0083] (2) The mixed embedding solution obtained in step (1) was added dropwise into 500 mL of a 2.0 wt% saturated boric acid solution containing calcium chloride, and cross-linked at 25° C. for 2 h to obtain the zero-valent iron sustained-release microcapsules.

[0084] The performance test was basically the same as that of Example 1, except that the zero-valent iron sustained-release microcapsules prepared in this comparative example were used.

[0085] Comparative Example 3

[0086] This comparative example provides a preparation method for a carbon source-anaerobic digestion bacteria sustained-release microcapsule:

[0087] (1) Add 30 mL of 10 g / L anaerobic digestion bacteria solution and 0.3 g of glucose to 70 mL of 2.0 wt% sodium alginate aqueous solution to obtain a microbial mixed embedding solution;

[0088] (2) The microbial mixed embedding solution obtained in step (1) is added dropwise into 500 mL of a 2.0 wt% saturated boric acid solution containing calcium chloride, and cross-linked at 25° C. for 2 h to obtain the carbon source-anaerobic digestion bacteria sustained-release microcapsules.

[0089] The performance test was basically the same as that of Example 1, except that the carbon source-anaerobic digestion bacteria sustained-release microcapsules prepared in this comparative example were used.

[0090] Combination Figure 2In Example 1, the concentration of p-nitrophenol in the water sample dropped to 19.75 mg / L after 1 day of treatment, and it could be completely removed after 2 days of treatment. In Comparative Example 2, the concentration of p-nitrophenol in the water sample dropped to 78.01 mg / L after 1 day of treatment, to 72.66 mg / L after 2 days of treatment, and to 69.99 mg / L after 3 days of treatment. In Comparative Example 3, the concentration of p-nitrophenol in the water sample dropped to 73.56 mg / L after 1 day of treatment, to 55.43 mg / L after 2 days of treatment, and to 43.88 mg / L after 3 days of treatment. This is due to the surface passivation effect. The performance of zero-valent iron in removing p-nitrophenol through physical and chemical reactions is limited in the later stage, which makes it difficult for the zero-valent iron sustained-release microcapsules prepared in Comparative Example 2 to operate for a long time. In the carbon source-anaerobic digestion bacteria sustained-release microcapsules prepared in Comparative Example 3, the microbial activity is inhibited by p-nitrophenol, resulting in slow reaction start-up and low repair efficiency. Compared with Comparative Example 2 and Comparative Example 3, in the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules of Example 1, the Fe element released by the zero-valent iron will increase the activity and environmental resistance of the anaerobic digestion bacteria, which is conducive to rapid startup and efficient repair; at the same time, the metabolic behavior of the anaerobic digestion bacteria will destroy the passivation film on the surface of the zero-valent iron, stimulating the zero-valent iron to continuously release the Fe element, thereby achieving long-term treatment.

Claims

1. A method for preparing zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules, characterized in that: The following steps are involved: S1. preparing a biochemical mixed embedding solution containing an embedding material and a gelling agent; S2. adding the biochemical mixed embedding solution obtained in step S1 to the cross-linking solution for cross-linking treatment to obtain zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules; Wherein, in step S1, the embedding material includes zero-valent iron, anaerobic digestion bacteria and a carbon source; The carbon source includes one, two or more of glucose, sodium acetate and sucrose; The zero-valent iron includes one or both of nano zero-valent iron and micron zero-valent iron; In step S1, the content of zero-valent iron in the biochemical mixed embedding solution is 40-80 mM; The anaerobic digestion bacteria are added through a bacterial solution containing anaerobic digestion bacteria, and the volume fraction of the bacterial solution containing anaerobic digestion bacteria is 20% to 40.0%; The concentration of anaerobic digestion bacteria in the bacterial solution is 10-20 g / L; The content of the carbon source is 2-4 g / L.

2. The method for preparing the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules according to claim 1, characterized in that: In step S1, the gelling agent is one or both of sodium alginate and polyvinyl alcohol.

3. The method for preparing the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules according to claim 2, characterized in that: In step S2, the cross-linking agent is one or both of a calcium chloride solution and a saturated boric acid solution containing calcium chloride.

4. The method for preparing the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules according to any one of claims 1 to 3, characterized in that: In step S2, the cross-linking treatment is performed for 1 to 4 hours at a temperature of 25 to 30°C.

5. The method for preparing the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules according to claim 4, characterized in that: The concentration of calcium chloride solution is 0.5~4.0wt%; The concentration of calcium chloride in the saturated boric acid solution containing calcium chloride is 0.5-4.0wt%.

6. A zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The zero-valent iron-carbon source-anaerobic digestion bacteria slow-release microcapsules include porous particles; The porous particles include a porous organic gel and an embedding material embedded in the porous organic gel; The embedding material includes zero-valent iron, anaerobic digestion bacteria and a carbon source; The carbon source includes one, two or more of glucose, sodium acetate and sucrose; The zero-valent iron includes one or both of nano zero-valent iron and micron zero-valent iron.

7. The zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule according to claim 6, characterized in that: The porous organic gel is obtained by cross-linking and polymerization of at least one gelling agent selected from sodium alginate and polyvinyl alcohol.

8. Use of zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsules prepared by the preparation method according to any one of claims 1 to 5 in treating organic wastewater.

9. Use of the zero-valent iron-carbon source-anaerobic digestion bacteria sustained-release microcapsule as described in any one of claims 6 to 7 in treating organic wastewater.

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