Sludge conditioning and dehydration composite agent and preparation method thereof

Abstract

The present invention relates to a sludge conditioning and dehydration composite agent and its preparation method. The composite agent comprises: a polymer comprising 1-vinyl-2-pyrrolidone copolymer units and copolymer units comprising alkenyl groups and amino or acylamino groups; and a tannic acid-inorganic salt complex. The composite agent can efficiently flocculate fine particles, increase sludge particle size, improve sludge-water separation speed, and promote deep sludge dehydration.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment and disposal, and in particular to a sludge conditioning and dehydration composite agent and a preparation method thereof. Technical Background

[0002] Sludge is an inevitable byproduct of the biological treatment process in municipal wastewater treatment plants. my country's annual production of concentrated sludge (at a moisture content of 98%) exceeds 300 million tons, placing immense pressure on its treatment and disposal. Sludge dewatering is a crucial step in sludge treatment and disposal, effectively reducing sludge volume and lowering subsequent transportation, treatment, and disposal costs.

[0003] Typically, sludge is mechanically dehydrated to reduce its moisture content. However, due to the presence of a large amount of hydrophilic substances in the sludge and its high moisture content, direct dehydration is very difficult. Therefore, pretreatment measures are generally required to adjust the sludge dewatering performance before dehydration to ensure effective dehydration. Currently, the main methods for dewatering sludge in municipal sewage treatment plants include physical conditioning, chemical conditioning, and microbial flocculation conditioning, which are used to improve the dewatering performance of sludge. However, the above methods still have some shortcomings in practical applications:

[0004] (1) Physical conditioning generally consumes a lot of energy. The sludge dewatering liquid after conditioning contains a large amount of chemical oxygen demand (COD) and ammonia nitrogen, which increases the treatment burden of the dewatering liquid;

[0005] (2) Although chemical conditioning can significantly improve the dewatering performance of sludge, the introduction of a large amount of inorganic matter will reduce the organic matter content in the sludge, which is not conducive to the subsequent resource utilization of the sludge and is likely to cause potential secondary pollution problems to the environment;

[0006] (3) Although microbial flocculation conditioning technology has broad development prospects, it has problems such as large amount of flocculants and high cost, which seriously restrict the large-scale production of microbial flocculants and greatly limit their widespread application in industry.

[0007] Currently, most urban sewage treatment plants in my country use polyelectrolytes to condition sludge. While these chemical agents can significantly improve sludge dewatering performance and solids recovery, the wide variety of agents and complex dosing procedures make optimal results difficult to guarantee. Furthermore, existing technologies using a single organic compound for conditioning can yield poor results, with the dewatered cake still containing as much as 80% moisture.

[0008] Therefore, a new sludge conditioning and dehydration compound agent is needed, which can efficiently flocculate fine particles to increase the sludge particle size, increase the mud-water separation speed, and promote deep sludge dehydration. Summary of the Invention

[0009] In response to the above-mentioned deficiencies in the prior art, the present invention aims to provide a sludge conditioning and dehydration composite agent and a preparation method thereof. To address the difficulties in dehydrating excess sludge generated by municipal sewage treatment plants and the potential secondary pollution to the environment caused by subsequent treatment, a sludge conditioning and dehydration composite agent is proposed. This agent utilizes the adsorption and bridging effect of tannic acid and an inorganic salt complex to promote sludge floc aggregation and increase the speed of mud-water separation. Furthermore, the agent utilizes the specific adsorption between 1-vinyl-2-pyrrolidone and tannic acid to link tannic acid into a polymer, reducing tannic acid hydrolysis. The agent also acts as a coprecipitant to enhance the flocculation effect of tannic acid complexed with organic matter.

[0010] In one aspect, the present invention provides a composite agent for sludge conditioning and dehydration, wherein the composite agent comprises:

[0011] (1) a high molecular weight polymer comprising a copolymerized unit of 1-vinyl-2-pyrrolidone and a copolymerized unit comprising an alkenyl group and an amino group or an acylamino group; and

[0012] (2) Tannic acid-inorganic salt complex.

[0013] In one embodiment of the present invention, the copolymerization unit comprising an alkenyl group and an amino group or an acylamino group is selected from vinylamine copolymerization unit, N-vinylformamide copolymerization unit, vinylacrylamide copolymerization unit, N,N-dimethylenebisacrylamide copolymerization unit or one or more combinations thereof.

[0014] In one embodiment of the present invention, the high molecular weight polymer comprises vinylamine copolymer units, N-vinylformamide copolymer units and vinyl acrylamide copolymer units.

[0015] In one embodiment of the present invention, the tannic acid-inorganic salt complex includes a tannic acid-aluminum salt complex, a tannic acid-iron salt complex, or a combination thereof.

[0016] In one embodiment of the present invention, the compound pharmaceutical further comprises 1-vinyl-2-pyrrolidone.

[0017] In one embodiment of the present invention, the compound pharmaceutical further comprises an oxidizing agent.

[0018] In one embodiment of the present invention, the oxidant comprises hydrogen peroxide, peracetic acid, persulfate, calcium peroxide, ferrate, sodium hypochlorite or a combination thereof.

[0019] In another aspect, the present invention provides a method for preparing the sludge conditioning and dehydration composite agent, the method comprising:

[0020] (1) reacting 1-vinyl-2-pyrrolidone with a copolymer containing an alkenyl group and an amino group or an acylamino group to form a high molecular weight polymer;

[0021] (2) contacting tannic acid with an inorganic salt to form the tannic acid-inorganic salt complex; and

[0022] (3) Mixing the high molecular weight polymer and the tannic acid-inorganic salt complex to form a sludge conditioning and dehydration composite agent.

[0023] In one embodiment of the present invention, the high molecular polymer is formed by reacting at 50-80° C. for 3-5 hours in the presence of an initiator and a cross-linking agent. Preferably, the initiator includes potassium persulfate, cerium sulfate, ammonium persulfate, hydrogen peroxide or a combination thereof; the cross-linking agent includes N,N-methylenebisacrylamide, divinylbenzene, diisocyanate or a combination thereof.

[0024] In one embodiment of the present invention, step (3) further comprises adding a stabilizer. Preferably, the stabilizer comprises isopropyl alcohol, thiourea, triethanolamine or a combination thereof.

[0025] In the present invention, the tannic acid-inorganic salt complex has an adsorption-bridging effect, which can promote the aggregation of sludge flocs and increase the speed of mud-water separation, which is beneficial for the capture and sweeping of flocs in the sludge. Furthermore, 1-vinyl-2-pyrrolidone and tannic acid have specific adsorption, which can form a polymer with tannic acid, thereby reducing tannic acid hydrolysis. Moreover, 1-vinyl-2-pyrrolidone itself is a coprecipitant, which can enhance the flocculation effect of tannic acid complexed with organic matter, resulting in no residue in the filtrate. Furthermore, 1-vinyl-2-pyrrolidone easily copolymerizes with other vinyl compounds to form high-molecular-weight long-chain polymers. Furthermore, the addition of an oxidant (e.g., peracetic acid, potassium persulfate, calcium peroxide, ferrate, etc.) can pre-oxidize sludge flocs and cells, promoting the decomposition of bioorganic matter in the sludge flocs and the release of bound water. Combined with the sludge conditioning and dehydration composite agent of the present invention, deep dehydration of sludge can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of preparing a composite agent for sludge conditioning and dehydration according to one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] The present application is described in detail below, and the features of the present application will be further revealed in the following specific description.

[0028] " Scope " disclosed herein is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution. In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0030] In this application, unless otherwise specified, the terms "include" and "comprising" used herein may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0031] In the description herein, unless otherwise indicated, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0032] In the prior art, single organic conditioning agents have poor effects, and the moisture content of the dehydrated mud cake is still as high as 80%. Treatment with a single oxidant will lead to deterioration of the sludge dewatering performance. The present invention replaces acrylamide polymer with a copolymer of ethyleneamine / N-vinylformamide / vinylacrylamide, which can reduce secondary pollution. At the same time, it integrates the characteristics of dense aluminum salt flocs, large iron salt flocs, and good organic-inorganic polymer adsorption bridging net capture effect. In the present invention, the use of the conditioning and dehydration composite agent (10-200 mg / gTS) and optionally supplemented with an oxidant (0-120 mg / gTS) can achieve deep dehydration of sludge (mud cake moisture content <60%).

[0033] polymers

[0034] In the present invention, the composite sludge conditioning and dehydration agent comprises a polymer comprising a copolymerized unit of 1-vinyl-2-pyrrolidone and a copolymerized unit comprising an alkenyl group and an amino group or an acylamino group. The copolymerized unit comprising an alkenyl group and an amino group or an acylamino group includes a copolymerized unit comprising an alkenyl group and an amino group, a copolymerized unit comprising an alkenyl group and an acylamino group, or a copolymerized unit comprising an alkenyl group, an amino group, and an acylamino group.

[0035] In a specific embodiment of the present invention, the copolymerization unit containing alkenyl and amino or amido group is selected from vinylamine copolymerization unit, N-vinylformamide copolymerization unit, vinylacrylamide copolymerization unit, N,N-dimethylenebisacrylamide copolymerization unit or one or more combinations thereof.

[0036]

[0037] In a specific embodiment of the present invention, the high molecular polymer comprises vinylamine copolymer units, N-vinylformamide copolymer units and vinyl acrylamide copolymer units.

[0038] In the present invention, the content of the high molecular weight polymer in the composite dehydration agent can be comprehensively evaluated and adjusted based on factors such as the water content of the sludge, the type and concentration of pollutants, the molecular weight of the polymer itself, the charge density, the characteristics of the process equipment, operational stability, treatment effect, and economic cost. In an embodiment of the present invention, the content of the high molecular weight polymer in the composite dehydration agent can be 5% to 25% by weight, 10% to 20% by weight, or 13% to 17% by weight.

[0039] Tannic acid-inorganic salt complex

[0040] In the present invention, the sludge conditioning and dehydration composite agent comprises a tannic acid-inorganic salt complex. In a specific embodiment of the present invention, the tannic acid-inorganic salt complex comprises a tannic acid-aluminum salt complex, a tannic acid-iron salt complex, or a combination thereof.

[0041]

[0042] In the formula, each R is independently selected from an alkyl group or an aryl group. In some embodiments of the present invention, each R is independently selected from a C1-C20 alkyl group or a C6-C18 aryl group.

[0043] In an embodiment of the present invention, the content of the tannic acid-inorganic salt complex in the sludge conditioning and dehydration composite agent may be 0.5 wt %-5.0 wt %, 1.0 wt %-4.0 wt %, or 2.0 wt %-3.0 wt %.

[0044] Optional additives

[0045] In the present invention, the sludge conditioning and dehydration composite agent further comprises one or more optional additives. In a preferred embodiment, the sludge conditioning and dehydration composite agent further comprises 1-vinyl-2-pyrrolidone. 1-vinyl-2-pyrrolidone acts as a coprecipitant, enhancing the flocculation effect of tannic acid complexed with organic matter, resulting in no residue in the filtrate. Furthermore, 1-vinyl-2-pyrrolidone readily copolymerizes with other vinyl compounds to form high-molecular-weight, long-chain polymers.

[0046] In the present invention, the content of 1-vinyl-2-pyrrolidone in the sludge conditioning and dehydration composite agent can be comprehensively evaluated and adjusted based on a variety of factors, including sludge properties, treatment objectives, and treatment conditions. In an embodiment of the present invention, the content of 1-vinyl-2-pyrrolidone in the sludge conditioning and dehydration composite agent can be 0.5% to 10.0% by weight, 1.0% to 8.0% by weight, 2.0% to 6.0% by weight, or 3.0% to 5.0% by weight.

[0047] In a preferred embodiment, the sludge conditioning and dehydration composite agent further comprises an oxidant. In a specific embodiment of the present invention, the oxidant comprises hydrogen peroxide, peracetic acid, persulfate, calcium peroxide, ferrate, sodium hypochlorite, or a combination thereof. In the present invention, the oxidant (e.g., ozone, peracetic acid, potassium persulfate, etc.) can pre-oxidize sludge flocs and cells, promoting the decomposition of bioorganic matter in the sludge flocs and the release of bound water. Combined use of the sludge conditioning and dehydration composite agent of the present invention can achieve deep dehydration of sludge.

[0048] In the present invention, the oxidant is used to enhance the oxidation and breakdown of sludge flocs and promote the release of bound water. In an embodiment of the present invention, the content of the oxidant in the dehydration composite agent can be 1.0% to 8.0% by weight, 2.0% to 7.0% by weight, 3.0% to 6.0% by weight, or 4.0% to 5.0% by weight.

[0049] Preparation method

[0050] The method for preparing the sludge conditioning and dehydration composite agent of the present invention comprises: reacting 1-vinyl-2-pyrrolidone with a copolymer containing an alkenyl group and an amino group or an acylamino group to form a high molecular polymer.

[0051] In a specific embodiment, the polymer is formed by reacting in the presence of an initiator and a crosslinking agent at a temperature of 50-80°C, 50-70°C, 50-60°C, 60-80°C, or 60-70°C for 3-5 hours or 3-4 hours. In a preferred embodiment, the initiator comprises potassium persulfate, cerium sulfate, ammonium persulfate, hydrogen peroxide, or a combination thereof. In a preferred embodiment, the crosslinking agent comprises N,N-methylenebisacrylamide, divinylbenzene, diisocyanate, or a combination thereof.

[0052] In the present invention, the initiator is mainly used for the cross-linking reaction of the polymer to increase the stability and durability of the polymer. In an embodiment of the present invention, the amount of the initiator used is generally 0.1% to 0.5% by weight, 0.2% to 0.4% by weight, or 0.3% to 0.4% by weight, based on the total weight of the reactants.

[0053] Crosslinking agents are used to form crosslinked structures in the polymer, increasing its stability in sludge and enhancing its dehydration efficiency. The amount of crosslinking agent used can be adjusted based on the type and properties of the specific polymer. In embodiments of the present invention, the amount of crosslinking agent used is typically 0.5% to 5% by weight, 1.0% to 4.0% by weight, or 2.0% to 3.0% by weight, based on the total weight of the reactants.

[0054] The method for preparing the sludge conditioning and dehydration composite agent of the present invention comprises: contacting tannic acid with an inorganic salt to form the tannic acid-inorganic salt complex.

[0055] In a specific embodiment, the inorganic salt is selected from iron salt or aluminum salt.

[0056] In a specific embodiment, the ratio of tannic acid to inorganic salt (iron salt / aluminum salt) is between 1:1 and 3:1 or between 1:1 and 2:1.

[0057] In specific embodiments, the reaction temperature may be between 25-60°C, between 30-50°C, or between 35-45°C.

[0058] In specific embodiments, the reaction time may be between 15 minutes and 2 hours or between 30 minutes and 1 hour.

[0059] The method for preparing the sludge conditioning and dehydration composite agent of the present invention comprises: mixing the high molecular polymer and the tannic acid-inorganic salt complex to form the sludge conditioning and dehydration composite agent.

[0060] In some embodiments, the amount of high molecular weight polymer used is in the range of 50-300 mg / L, depending on the sludge characteristics, dewatering equipment, and the requirements for the final dewatering effect.

[0061] In some embodiments, the tannic acid-inorganic salt complex is used in a concentration range of 100-500 mg / L, taking into account the complexing capacity and cost of the complex.

[0062] In a specific embodiment, the mixing step further includes adding a stabilizer to enhance the stability of the high molecular weight polymer and the tannic acid-inorganic salt complex, thereby improving the storage stability of the final product, the sludge conditioning and dehydration composite agent. In a preferred embodiment, the stabilizer includes isopropyl alcohol, thiourea, triethanolamine, or a combination thereof.

[0063] application

[0064] The application field of sludge conditioning and dehydration compound agents is very wide, mainly including various engineering treatment sites, not limited to urban sewage treatment plants, petrochemical enterprises, food industry, pulp and paper manufacturing industry, mining, metallurgical industry, river restoration, etc., and is used to treat sludge generated by industry, domestic sewage, river management, etc.

[0065] Sludge conditioning and dehydration compound agents are primarily used in the sludge conditioning and dehydration stage. Sludge is the solid residue left over from the sewage treatment process and contains a large amount of water and harmful substances. During this stage, the compound agent can effectively improve the sludge's filterability, enhance its dehydration efficiency, and reduce the difficulty and cost of subsequent treatment.

[0066] The sludge conditioning and dehydration compound enhances the agglomeration of sludge particles through complexation, improving the sludge structure from a sparse to a compact state while maintaining its stability, which facilitates subsequent filter press dehydration. It also improves the efficiency of solid-liquid separation during the sludge dehydration process, thereby reducing the sludge burden and sludge treatment costs. It also significantly lowers the concentration of some toxic and hazardous substances, minimizing harm to the environment and human health.

[0067] Example

[0068] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0069] In the following examples, sludge was obtained from Changzhou Shenshuichengbei Wastewater Treatment Plant; polyvinylamine was purchased from Hubei Shiteng Chemical Technology Co., Ltd.; polyacrylamide was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; poly (N-vinyl formamide) was purchased from Shanghai Yaji Biotechnology Co., Ltd.; 1-vinyl-2-pyrrolidone was purchased from Guangzhou Ruiyue Trading Co., Ltd.; sodium persulfate was purchased from Fujian Minglin Technology Co., Ltd.; hydrogen peroxide was purchased from Anhui Andenuo Chemical Products Sales Co., Ltd.; N,N-methylenebisacrylamide was purchased from Hubei Linyang Chemical Co., Ltd.; tannic acid was purchased from Hebei Yaxin Biotechnology Co., Ltd.; ferric chloride was purchased from Tianjin Chemical Reagent Co., Ltd.; and thiourea was purchased from Hubei Taihechang Biotechnology Co., Ltd.

[0070] Example 1

[0071] 1. Preparation of polymers

[0072] At room temperature, 8 g of polyvinylamine, 8 g of polyacrylamide, 8 g of poly (N-vinylformamide), 2.5 g of 1-vinyl-2-pyrrolidone, 1.6 g of hydrogen peroxide, and 1.4 g of N,N-methylenebisacrylamide were weighed separately and added to a 250 ml three-necked flask. The mixture was stirred continuously and heated in a water bath at 75°C for 3 hours to obtain 15.6 g of a high molecular weight polymer.

[0073] 2. Preparation of Tannic Acid-Fe 3+ complex

[0074] At room temperature, 3g of tannic acid was weighed to prepare a tannic acid solution, and 2g of ferric chloride was added and stirred continuously. The reaction generated a black precipitate, which was allowed to settle and the supernatant was filtered out to obtain a black precipitate. The black precipitate was washed with ethanol to obtain 1.4g of tannic acid-Fe 3+ complex.

[0075] 3. Prepare compound agent for sludge conditioning and dehydration.

[0076] At room temperature, 15.6g of polymer, 1.4g of tannic acid-Fe 3+ The complex is mixed with 0.5 g of thiourea to form a sludge conditioning and dehydration composite agent.

[0077] Test Example 1

[0078] First, 1% calcium peroxide was added to the sludge as an oxidant and stirred for 10 minutes. The sludge conditioning and dehydration compound prepared in the above preparation example was then added and stirred for 30 minutes to thoroughly mix the compound with the sludge. The stirred sludge was then passed through a plate and frame filter press for 2 hours at a pressure of 1.5-2 MPa.

[0079] Through observation and measurement, the capillary water absorption time of the sludge was reduced from 112.7s without conditioning to 13.2s, and the moisture content of the dehydrated sludge cake was reduced to 58.7%.

[0080] Compared to the sludge cake obtained with 1% calcium peroxide alone, the moisture content of the sludge cake obtained in Example 1 was reduced by 82%. Compared to the sludge cake obtained without the dehydration compound, the moisture content of the sludge cake obtained in Example 1 was reduced by 79%. Furthermore, the sludge-water separation rate in Example 1 was also faster, with a sedimentation ratio (SV30) of 15%, compared to 35% for sludge using conventional dehydration compounds. Example 1 significantly reduced sludge settling time.

[0081] Comparative Example 1

[0082] In the same sewage treatment plant, only high molecular weight polymer conditioner was added to the sludge of the same specifications and stirred for 30 minutes to fully mix the conditioner and the sludge.

[0083] Filtration was performed using the same filter press as in Example 1. The dehydrated sludge cake had a moisture content of 76%, significantly lower than the dehydration compound used in Example 1. The sludge-water separation rate was also slower than that achieved with the sludge conditioning and dehydration compound, with a sedimentation ratio (SV30) of 24%.

[0084] Comparative Example 2

[0085] In the same sewage treatment plant, tannic acid-Fe was added to the sludge of the same specifications. 3+ Complex conditioner and stir for 30 minutes to fully mix the conditioner and sludge.

[0086] Filter pressing was performed using the same method and filter press as in Example 1. The dehydrated mud cake had a moisture content of 78%, significantly lower than the dehydration compound. The mud-water separation rate was also slower than that achieved with the sludge conditioning and dehydration compound, with a sedimentation ratio (SV30) of 27%.

[0087] As can be seen from Example 1, Test Example 1, and Comparative Examples 1-2, the composite sludge conditioning and dehydration agent of the present invention is significantly superior to a single organic sludge conditioning agent in terms of deep dehydration and accelerated sludge-water separation. Therefore, the composite sludge conditioning and dehydration agent has a better application prospect.

[0088] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A sludge conditioning and dehydration compound agent, wherein: The compound medicine comprises: (1) a high molecular weight polymer comprising a copolymerized unit of 1-vinyl-2-pyrrolidone and a copolymerized unit comprising an alkenyl group and an amino group or an acylamino group; and (2) Tannic acid-inorganic salt complex.

2. The sludge conditioning and dehydration composite agent according to claim 1, wherein: The copolymerization unit containing alkenyl and amino or amido groups is selected from vinylamine copolymerization units, N-vinylformamide copolymerization units, vinylacrylamide copolymerization units, N,N-dimethylenebisacrylamide copolymerization units or one or more combinations thereof.

3. The sludge conditioning and dehydration composite agent according to claim 1, wherein: The high molecular polymer comprises vinylamine copolymer units, N-vinyl formamide copolymer units and vinyl acrylamide copolymer units.

4. The sludge conditioning and dehydration composite agent according to claim 1, wherein: The tannic acid-inorganic salt complex includes a tannic acid-aluminum salt complex, a tannic acid-iron salt complex or a combination thereof.

5. The sludge conditioning and dehydration composite agent according to claim 1, wherein: The compound medicine further comprises 1-vinyl-2-pyrrolidone.

6. The sludge conditioning and dehydration composite agent according to claim 1, wherein: The composite pharmaceutical composition further comprises an oxidizing agent.

7. The sludge conditioning and dehydration composite agent according to claim 6, wherein: The oxidizing agent includes hydrogen peroxide, peracetic acid, persulfate, calcium peroxide, ferrate, sodium hypochlorite or a combination thereof.

8. A method for preparing the sludge conditioning and dehydration composite agent according to any one of claims 1 to 7, the method comprising: (1) reacting 1-vinyl-2-pyrrolidone with a copolymer containing an alkenyl group and an amino group or an acylamino group to form a high molecular weight polymer; (2) contacting tannic acid with an inorganic salt to form the tannic acid-inorganic salt complex; and (3) Mixing the high molecular weight polymer and the tannic acid-inorganic salt complex to form a sludge conditioning and dehydration composite agent.

9. The method according to claim 8, wherein The high molecular weight polymer is formed by reacting at 50-80° C. for 3-5 hours in the presence of an initiator and a cross-linking agent.

10. The method according to claim 9, wherein: The initiator includes potassium persulfate, cerium sulfate, ammonium persulfate, hydrogen peroxide or a combination thereof; the crosslinking agent includes N,N-methylenebisacrylamide, divinylbenzene, diisocyanate or a combination thereof.

11. The method according to claim 9, wherein Step (3) also includes adding a stabilizer.

12. The method according to claim 11, wherein The stabilizer includes isopropyl alcohol, thiourea, triethanolamine or a combination thereof.

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