Composite modified flocculant, preparation device and method thereof, and application thereof

Abstract

The application discloses a composite modified flocculant and a preparation device and method thereof and application thereof, and belongs to the technical field of sewage treatment, so as to solve the technical problems of weak destabilization capacity, loose floc, and difficulty in penetrating sludge and being shielded by positive charge of the existing flocculant when treating high-organic and difficult-to-dewater residual activated sludge. The composite modified flocculant is composed of the following components in terms of solid mass: 1-13.2% of polyethylene amidine, 20-51.4% of cationic polyacrylamide, 11.4-40% of polydimethyl diallyl ammonium chloride and 10-60% of inorganic flocculant, and the sum of the weight parts of the polyethylene amidine, the cationic polyacrylamide, the polydimethyl diallyl ammonium chloride and the inorganic flocculant is 100%. The composite modified flocculant can treat various complex water qualities, the formed floc is more compact and has a larger particle size, the settling speed is fast, the treatment efficiency is improved, and the sludge volume is reduced.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a composite modified flocculant, its preparation apparatus, preparation method and application. Background Technology

[0002] Sludge produced by wastewater treatment plants is characterized by high water content (usually >98%), high organic matter, strong hydrophilicity, and difficulty in dewatering. If it is not effectively reduced in volume, it will bring serious environmental and economic burdens.

[0003] Cationic polyacrylamide (CPAM) is one of the most widely used organic polymer flocculants in sludge dewatering and wastewater treatment. CPAM has strong bridging ability, produces large and dense flocs, and is highly adaptable to different pH (5-9) and temperature conditions. Commercially available CPAM is mostly in emulsion or powder form, is easily soluble, and offers good economic benefits. It can be used in various industries such as municipal sewage sludge, industrial wastewater, papermaking, printing and dyeing, and food processing.

[0004] Although CPAM is widely used, it has limited charge density and weak destabilization ability when treating high-organic-matter, difficult-to-dewater residual activated sludge. It is incompletely destabilizing highly negatively charged activated sludge, leading to poor subsequent bridging effects. The flocs formed by CPAM and high-organic-matter residual activated sludge are loose, have poor pressure resistance, and often exhibit a "dendritic" structure with large internal pores and strong water retention capacity. It also has poor adaptability to high-organic-matter sludge; CPAM has difficulty penetrating the EPS layer and cannot effectively disrupt the floc structure, resulting in "surface flocculation" while retaining a large amount of bound water internally. Furthermore, it is susceptible to damage from polyvalent anions (such as PO4). 3- SO4 2- It will shield positive charges and reduce efficiency; industrial-grade CPAM may contain trace amounts of unreacted acrylamide (<0.05%); acrylamide is a neurotoxin and a potential carcinogen, posing environmental and health risks.

[0005] Therefore, there is an urgent need to develop a composite modified flocculant that can effectively treat excess activated sludge with high organic matter content and difficult dewatering. Summary of the Invention

[0006] This application discloses a composite modified flocculant and its preparation device, preparation method and application, in order to solve the technical problems of flocculants in related technologies when treating high organic matter and difficult-to-dewater residual activated sludge, such as weak destabilization ability, loose flocs, difficulty in penetrating sludge and shielding of positive charges.

[0007] To solve the above problems, this application adopts the following technical solution: In a first aspect, this application provides a composite modified flocculant, which is composed of the following components by solid mass: 1-13.2% polyvinylamine (PVAD), 20-51.4% cationic polyacrylamide, 11.4-40% polydimethyldiallylammonium chloride (PDADMAC), and 10-60% inorganic flocculant, wherein the sum of the weight parts of polyvinylamine, cationic polyacrylamide, polydimethyldiallylammonium chloride, and inorganic flocculant is 100%.

[0008] Furthermore, the flocculant consists of the following components by solid mass: 5-13.2% polyvinylamine, 20-40% cationic polyacrylamide, 20-30% polydimethyldiallylammonium chloride, and 20-50% inorganic flocculant.

[0009] Furthermore, polyvinylamidine has a molecular weight of 20,000-100,000 and a cationicity of 30%-70%.

[0010] Furthermore, cationic polyacrylamide has a molecular weight of 8 million to 12 million and an ionicity of 30% to 60%.

[0011] Furthermore, the molecular weight of polydimethyldiallylammonium chloride is 50,000-200,000, and its cationicity is 20%-90%.

[0012] Furthermore, the inorganic flocculant is selected from at least one of polyferric sulfate, aluminum sulfate, ferric chloride, and polyaluminum chloride.

[0013] Secondly, this application also provides a preparation apparatus for a composite modified flocculant of the first aspect, comprising a three-chamber preparation module, an inorganic flocculant dissolving tank, and a polydimethyldiallyl ammonium chloride dissolving tank; the inorganic flocculant dissolving tank is connected to the three-chamber preparation module for introducing an inorganic flocculant solution therein, and the polydimethyldiallyl ammonium chloride dissolving tank is connected to the three-chamber preparation module for introducing a polydimethyldiallyl ammonium chloride solution therein, the three-chamber preparation module comprising a premixing tank, a maturation tank, and a storage tank connected in sequence.

[0014] Thirdly, this application also provides a method for preparing a composite modified flocculant, comprising the following steps: Step 100: Mix 1-13.2 parts by weight of polyvinylamidine and 20-51.4 parts by weight of cationic polyacrylamide in a three-chamber preparation module, then add deionized water to prepare a mixed solution with a mass fraction of 1-5‰; add deionized water to 11.4-40 parts by weight of polydimethyldiallyl ammonium chloride in a polydimethyldiallyl ammonium chloride dissolving tank to prepare a polydimethyldiallyl ammonium chloride solution with a mass fraction of 5%; mix 10-60 parts by weight of inorganic flocculant with deionized water at a mass ratio of 1:2-4 in an inorganic flocculant dissolving tank to obtain an inorganic flocculant solution; Step 200: Add the polydimethyldiallylammonium chloride solution to the three-chamber preparation module and mix it with the mixed solution to obtain an organic flocculant solution; Step 300: Mix the organic flocculant solution and the inorganic flocculant solution in a certain proportion to obtain the composite modified flocculant.

[0015] Furthermore, in step 100, the mixed solution is prepared in a premixing tank and then transferred to a maturation tank for maturation; in steps 200 and 300, the maturated mixed solution is transferred to a storage tank and first mixed with polydimethyldiallylammonium chloride solution to obtain an organic flocculant solution, and then the organic flocculant solution is mixed with an inorganic flocculant solution to obtain a composite modified flocculant.

[0016] Fourthly, this application also provides an application of a composite modified flocculant in sludge dewatering, wherein 1-5 kg ​​of the composite modified flocculant is added per ton of dry sludge.

[0017] The technical solution adopted in this application can achieve the following beneficial effects: Cationic organic polymers (such as CPAM, PDADMAC, and PVAD) carry a positive charge, which can effectively neutralize negatively charged colloidal particles in water and reduce the zeta potential; at the same time, their long-chain structure can aggregate small particles into large flocs through bridging. Inorganic components (such as Al) 3+ Fe 3+ Hydrolysis products can rapidly form micro-flocculation nuclei, providing adsorption sites for organic polymers and accelerating floc formation and density.

[0018] Among organic flocculants, PVAD has a high cationic density, which can generate compact, highly hydrophobic, and robust flocs; moreover, its aqueous solution has low viscosity and excellent reactivity with sludge. CPAM can form large and tough flocs, improving floc density, reducing breakage, and facilitating sedimentation or filtration. PDADMAC is permanently positively charged, unaffected by pH, and has a strong ability to neutralize negatively charged colloids.

[0019] During flocculation, inorganic flocculants and small-molecule cationic polymeric flocculants (PDADMAC and PVAD) act first on the sludge or wastewater, rapidly destabilizing it. The inorganic flocculant quickly forms micro-flocs; PDADMAC and PVAD further neutralize residual negative charges, preventing colloid restabilization; the two work synergistically to significantly increase the initial flocculation rate. The surface potential of particles treated with inorganic flocculants and small-molecule cationic polymeric flocculants is close to zero, which is conducive to the adsorption of long-chain CPAM; CPAM forms large and dense macro-flocs with rapid settling and low water content.

[0020] PDADMAC provides strong cationic sites, enhancing the anchoring of CPAM on the particle surface; CPAM compensates for the insufficient bridging ability of PDADMAC, and the combined use of the two can reduce the dosage of each, thus lowering costs. Extremely low dosages of PVAD can rapidly initiate the flocculation process, making it particularly suitable for low-turbidity, difficult-to-treat wastewater (such as oily or humic acid-containing water); synergistically with PDADMAC, it covers colloids with different charge densities. Inorganic components perform some charge neutralization and entrapment functions, reducing the dosage of expensive organic polymers (especially PVAD); at the same time, it avoids the "colloidal protection" or restabilization phenomenon caused by excessive polymers. Inorganic flocculants can also adjust the pH to create a more suitable acid-base environment for PVAD, resulting in better flocculation. Excessive CPAM or PDADMAC can easily lead to "over-flocculation," making the system viscous and hindering dehydration. PVAD, being a medium-to-low viscosity polymer, does not significantly increase the system viscosity after addition, thus alleviating or even avoiding the viscosity problem to some extent. CPAM tends to retain hydrophilic amide groups, resulting in strong water-holding capacity that is not conducive to dehydration. PVAD promotes the formation of hydrophobic flocs, reducing capillary water absorption.

[0021] This composite modified flocculant can treat a variety of complex water qualities, such as high turbidity, high organic content, oily wastewater, dyeing and printing wastewater, papermaking wastewater, and municipal sewage. The composite system has stronger pH adaptability, forms denser flocs with larger particle sizes, and settles faster, which helps shorten sedimentation or flotation time and improve treatment efficiency. It also reduces sludge volume and lowers subsequent sludge treatment costs. Due to the synergistic effect, the total dosage is usually lower than that of a single flocculant, especially reducing the amount of expensive organic polymers used, thus lowering reagent costs while ensuring effectiveness. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart of the preparation method of the composite modified flocculant of this application; Figure 2 This is a schematic diagram of the preparation device for composite modified flocculants.

[0024] In the diagram: 100, three-box preparation module; 110, premixing box; 120, maturation box; 130, storage box; 200, inorganic flocculant dissolving box; 300, polydimethyldiallyl ammonium chloride dissolving box. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0027] CPAM is one of the most widely used organic polymer flocculants in sludge dewatering and wastewater treatment. However, when treating high-organic-matter, difficult-to-dewater residual activated sludge, CPAM has limited charge density and weak destabilization ability, resulting in incomplete destabilization of highly negatively charged activated sludge and poor subsequent bridging effect. The flocs formed by CPAM and high-organic-matter residual activated sludge are loose, have poor pressure resistance, and often exhibit a "dendritic" structure with large internal pores and strong water retention capacity. It also has poor adaptability to high-organic-matter sludge; CPAM has difficulty penetrating the EPS layer and cannot effectively destroy the floc structure, leading to "surface flocculation" while retaining a large amount of bound water internally. Furthermore, it exhibits poor adaptability to high-organic-matter sludge, as CPAM struggles to penetrate the EPS layer and effectively disrupt the floc structure, resulting in "surface flocculation" while retaining a large amount of bound water internally. 3- SO4 2- It will shield positive charges and reduce efficiency; industrial-grade CPAM may contain trace amounts of unreacted acrylamide (<0.05%); acrylamide is a neurotoxin and a potential carcinogen, posing environmental and health risks.

[0028] PVAD has a high cationic density, which can generate compact, highly hydrophobic, and robust flocs; its aqueous solution has low viscosity and excellent reactivity with sludge. However, PVAD has a significantly higher application cost, and its low molecular weight results in weak bridging ability.

[0029] Therefore, there is an urgent need to develop a composite modified flocculant that combines CPAM and PVAD to effectively treat excess activated sludge with high organic matter content and difficult dewatering.

[0030] The following is in conjunction with the appendix Figures 1 to 2 The composite modified flocculant, its preparation device, preparation method, and application provided in this application are described in detail through specific embodiments and application scenarios.

[0031] This application provides a composite modified flocculant, which is composed of the following components by solid mass: 1-13.2% polyvinylammonium, 20-51.4% cationic polyacrylamide, 11.4-40% polydimethyldiallyl ammonium chloride and 10-60% inorganic flocculant, wherein the sum of the weight parts of polyvinylammonium, cationic polyacrylamide, polydimethyldiallyl ammonium chloride and inorganic flocculant is 100%.

[0032] In this embodiment, cationic organic polymers (such as CPAM, PDADMAC, and PVAD) carry a positive charge, which can effectively neutralize negatively charged colloidal particles in water and reduce the zeta potential; at the same time, their long-chain structure can aggregate small particles into large flocs through bridging. Inorganic components (such as Al) 3+ Fe 3+ Hydrolysis products can rapidly form micro-flocculation nuclei, providing adsorption sites for organic polymers and accelerating floc formation and density.

[0033] Among organic flocculants, PVAD has a high cationic density, which can generate compact, highly hydrophobic, and robust flocs; moreover, its aqueous solution has low viscosity and excellent reactivity with sludge.

[0034] CPAM is a linear polymer with polyacrylamide as its main chain and cationic groups in its side chains. Its molecular weight typically reaches millions. The CPAM chain structure spans multiple pre-destabilized particles, forming large and robust flocs. This increases floc density, reduces breakage, and facilitates sedimentation or filtration.

[0035] PDADMAC is a homopolymer or copolymeric strong cationic polyelectrolyte with a quaternary ammonium salt structure, good water solubility, and medium molecular weight. The quaternary ammonium groups are permanently positively charged, unaffected by pH, and have a strong ability to neutralize negatively charged colloids.

[0036] During flocculation, inorganic flocculants and small-molecule cationic polymeric flocculants (PDADMAC and PVAD) act first on the sludge or wastewater, rapidly destabilizing it. Inorganic flocculants quickly form micro-flocs; PDADMAC and PVAD further neutralize residual negative charges, preventing colloid restabilization; the synergistic effect of both significantly shortens the induction period and increases the initial flocculation rate.

[0037] The surface potential of particles treated with inorganic flocculants and small molecule cationic polymeric flocculants is close to zero, which is conducive to the adsorption of long CPAM chains. CPAM spans multiple micro flocs to form large and dense macro flocs, which settle quickly and have low water content.

[0038] PDADMAC provides strong cationic sites, enhancing the anchoring of CPAM on the particle surface; CPAM compensates for the insufficient bridging ability of PDADMAC, and the combined use of the two can reduce the dosage of each, thus lowering costs. Extremely low dosages of PVAD can rapidly initiate the flocculation process, making it particularly suitable for low-turbidity, difficult-to-treat wastewater (such as oily or humic acid-containing water); synergistically with PDADMAC, it covers colloids with different charge densities. Inorganic components perform some charge neutralization and entrapment functions, reducing the dosage of expensive organic polymers (especially PVAD); at the same time, it avoids the "colloidal protection" or restabilization phenomenon caused by excessive polymers. Inorganic flocculants can also adjust the pH to create a more suitable acid-base environment for PVAD, resulting in better flocculation. Excessive CPAM or PDADMAC can easily lead to "over-flocculation," making the system viscous and hindering dehydration. PVAD, being a medium-to-low viscosity polymer, does not significantly increase the system viscosity after addition, thus alleviating or even avoiding the viscosity problem to some extent. CPAM tends to retain hydrophilic amide groups, resulting in strong water-holding capacity that is not conducive to dehydration. PVAD promotes the formation of hydrophobic flocs, reducing capillary water absorption.

[0039] This composite modified flocculant can treat a variety of complex water qualities, such as high turbidity, high organic content, oily wastewater, dyeing and printing wastewater, papermaking wastewater, and municipal sewage. The composite system has stronger pH adaptability, forms denser flocs with larger particle sizes, and settles faster, which helps shorten sedimentation or flotation time and improve treatment efficiency. It also reduces sludge volume and lowers subsequent sludge treatment costs. Due to the synergistic effect, the total dosage is usually lower than that of a single flocculant, especially reducing the amount of expensive organic polymers used, thus lowering reagent costs while ensuring effectiveness.

[0040] In some embodiments, the flocculant comprises the following components by solid mass: 5-13.2% polyvinylammonium, 20-40% cationic polyacrylamide, 20-30% polydimethyldiallylammonium chloride, and 20-50% inorganic flocculant.

[0041] In some embodiments, the molecular weight of polyvinylamidine is 20,000 to 100,000, and the cationicity is 30% to 70%.

[0042] In some embodiments, the cationic polyacrylamide has a molecular weight of 8 million to 12 million and an ionic degree of 30 to 60%.

[0043] In some embodiments, the molecular weight of polydimethyldiallylammonium chloride is 50,000 to 200,000, and the cationicity is 20% to 90%.

[0044] In some embodiments, the inorganic flocculant is selected from at least one of polyferric sulfate, aluminum sulfate, ferric chloride, and polyaluminum chloride.

[0045] Reference Figure 2This application also provides a preparation apparatus for a first aspect of a composite modified flocculant. The preparation apparatus includes a three-chamber preparation module 100 for preparing the composite modified flocculant, an inorganic flocculant dissolving tank 200, and a polydimethyldiallyl ammonium chloride dissolving tank 300. The inorganic flocculant dissolving tank 200 is connected to the three-chamber preparation module 100 for introducing an inorganic flocculant solution into it. The polydimethyldiallyl ammonium chloride dissolving tank 300 is connected to the three-chamber preparation module 100 for introducing a polydimethyldiallyl ammonium chloride solution into it. The three-chamber preparation module 100 includes a premixing tank 110, a maturation tank 120, and a storage tank 130 connected in sequence.

[0046] For example, solid inorganic flocculant is added to the inorganic flocculant dissolving tank 200 in a designed ratio and mixed with water using a stirring device (such as a paddle or turbine agitator). The dissolving process may be aided by heating (e.g., in winter) or pH adjustment to accelerate dissolution and prevent hydrolysis and precipitation.

[0047] Add solid or liquid PDADMAC to a polydimethyldiallylammonium chloride dissolving tank (300°C), dilute with water to a suitable concentration, and dissolve by stirring at low speed. Since PDADMAC is a highly water-soluble cationic polymer, it dissolves quickly; therefore, high-speed shearing should be avoided to prevent molecular chain breakage.

[0048] PVAD and CPAM are usually added directly to the premix tank 110 in solid or concentrated form, or pre-prepared in a small-dose dissolving tank and then pumped in. Because the dosage is small and they are easily soluble, there is no need for a separate large dissolving tank.

[0049] PVAD and CPAM are dissolved and mixed in a premixing tank 110, and then matured in a maturation tank 120 before being transferred to a storage tank 130. The polydimethyldiallylammonium chloride solution and the inorganic flocculant solution are then pumped sequentially into the premixing tank 110. Low-speed stirring (30-60 rpm) is used in the maturation tank 120 to avoid shear damage to the forming composite polymer structure. The maturation time is typically 20-60 minutes.

[0050] In this embodiment, the three boxes are separated, separating the mixing, maturation, and storage functions to avoid cross-interference and improve controllability. This design is well-suited for the preparation of the aforementioned composite modified flocculant, effectively preventing unintended reactions or effects of the components and improving the actual performance of the composite modified flocculant.

[0051] Reference Figure 1 This application also provides a method for preparing a composite modified flocculant, comprising the following steps: Step 100: Mix 1-13.2 parts by weight of polyvinylamidine and 20-51.4 parts by weight of cationic polyacrylamide in the three-chamber preparation module 100, then add deionized water to prepare a mixed solution with a mass fraction of 1-5‰; add 11.4-40 parts by weight of polydimethyldiallyl ammonium chloride to deionized water in the polydimethyldiallyl ammonium chloride dissolving tank 300 to prepare a polydimethyldiallyl ammonium chloride solution with a mass fraction of 5%; mix 10-60 parts by weight of inorganic flocculant with deionized water at a mass ratio of 1:2-4 in the inorganic flocculant dissolving tank 200 to dissolve and obtain an inorganic flocculant solution; Step 200: Add the polydimethyldiallylammonium chloride solution to the three-box preparation module 100 and mix it with the mixed solution to obtain an organic flocculant solution; Step 300: Mix the organic flocculant solution and the inorganic flocculant solution in a certain proportion to obtain the composite modified flocculant.

[0052] In this embodiment, PVAD and CPAM are first mixed to construct an organic polymer synergistic framework. CPAM is an ultra-high molecular weight linear polymer that is sensitive to mechanical shear. If it is directly dissolved in a high concentration of inorganic salts or a strong electrolyte environment, it is prone to molecular chain curling and degradation due to "salting out" or local high ionic strength.

[0053] Pre-dissolving CPAM with PVAD in low-ionic-strength deionized water helps protect the structural integrity of CPAM. PVAD promotes the dispersion and activation of CPAM; as a small-molecule polyamine with excellent water solubility, PVAD can act as a co-solvent or dispersant, helping CPAM dry powder to quickly wet and depolymerize, preventing the formation of fisheyes (undissolved micelles). Pre-mixing and maturing CPAM with PVAD using low-speed stirring avoids damage to CPAM from high shear. PVAD provides a high density of positive charge sites, while CPAM provides a long-chain bridging structure. The two pre-form charge-backbone synergistic units in dilute solution, laying the foundation for subsequent fusion with PDADMAC.

[0054] The subsequent addition of a polydimethyldiallyl ammonium chloride solution enhances charge density and stability. This avoids the risk of precipitation caused by direct contact between PDADMAC and inorganic salts; although PDADMAC is a strong cationic polyelectrolyte, it is susceptible to precipitation at high Al concentrations. 3+ / Fe 3+ In its presence, it may produce turbidity or gel due to excessive charge neutralization or complexation.

[0055] First, PVAD and CPAM are mixed to form an organic protective layer, then inorganic components are introduced to buffer ion impacts. This achieves gradient composite of the organic cationic components. Mixing in this order allows the three components to gradually assemble at the molecular scale, forming a multi-level charge-structure complex, which is superior to the random aggregation of a single mixing. Moreover, if a high concentration of PVAD / MAC is added first, followed by CPAM, the sudden increase in local viscosity can easily lead to uneven mixing. In this embodiment, the stepwise addition maintains a moderate viscosity, which is beneficial for stirring and mass transfer.

[0056] Finally, the introduction of an inorganic flocculant solution enables the formation of an organic-encapsulated-inorganic core structure. Inorganic flocculants rapidly hydrolyze in water to generate polynuclear hydroxyl complexes. If added before the polymer is fully dispersed, irreversible precipitation due to localized supersaturation can occur, reducing the effective components. Adding the flocculant after the organic polymer system has stabilized allows the inorganic hydrolysis products to be captured or encapsulated by the organic chains, forming stable organic-inorganic hybrid particles. This promotes the formation of core-shell or network-like intercalation structures. The organic polymers pre-form a network within which inorganic ions hydrolyze and nucleate, constructing a composite structure with inorganic as the condensation nucleus and organic as the bridging shell, possessing the triple functions of charge neutralization, network capture, and bridging.

[0057] In addition, preparing the mixed solution at a low concentration of 1-5‰ can ensure that the CPAM polymer is fully extended and avoid entanglement of linear polymer chains; diluting the inorganic flocculant solution at a ratio of 1:2-4 can control the hydrolysis rate of the inorganic flocculant and prevent it from exothermicly or gelling.

[0058] In some embodiments, in step 100, the mixed solution is prepared in a premixing tank 110 and then transferred to a maturation tank 120 for maturation; in steps 200 and 300, the maturated mixed solution is transferred to a storage tank 130 and first mixed with a polydimethyldiallylammonium chloride solution to obtain an organic flocculant solution, and then the organic flocculant solution is mixed with an inorganic flocculant solution to obtain a composite modified flocculant.

[0059] This application also provides an application of a composite modified flocculant in sludge dewatering, wherein 1-5 kg ​​of the composite modified flocculant is added per ton of dry sludge.

[0060] Example 1

[0061] The composite modified flocculant in this embodiment consists of the following components by solids mass: 10% polyvinylamidine, 40% cationic polyacrylamide, 20% polydimethyldiallyl ammonium chloride, and 30% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0062] The composite modified flocculant in this embodiment was prepared by the following method: 300 g of polyvinylamine and 1200 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 600 g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 900 g of ferric chloride and 2.7 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0063] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 74.2%.

[0064] Example 2

[0065] The composite modified flocculant in this embodiment consists of the following components by solids mass: 1% polyvinylamidine, 44% cationic polyacrylamide, 22% polydimethyldiallylammonium chloride, and 33% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallylammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0066] The composite modified flocculant in this embodiment was prepared by the following method: 30 g of polyvinylamine and 1320 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 660 g of polydimethyldiallyl ammonium chloride to deionized water in a polydimethyldiallyl ammonium chloride dissolving tank 300 to prepare a 5% polydimethyldiallyl ammonium chloride solution. 990 g of ferric chloride and 2.97 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0067] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 81.2%.

[0068] Example 3

[0069] The composite modified flocculant in this embodiment consists of the following components by solids mass: 5.5% polyvinylamidine, 42% cationic polyacrylamide, 21% polydimethyldiallyl ammonium chloride, and 31.5% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0070] The composite modified flocculant in this embodiment was prepared by the following method: 165 g of polyvinylamine and 1260 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 630 g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 945g of ferric chloride and 2.835 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0071] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 79.3%.

[0072] Example 4

[0073] The composite modified flocculant in this embodiment consists of the following components by solids mass: 11.6% polyvinylammonium chloride, 30% cationic polyacrylamide, 23.3% polydimethyldiallyl ammonium chloride, and 35.1% ferric chloride. The polyvinylammonium chloride has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0074] The composite modified flocculant in this embodiment was prepared by the following method: 348 g of polyvinylamine and 900 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 699g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a 5% polydimethyl diallyl ammonium chloride solution. 1053g of ferric chloride and 3.159kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0075] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 74.0%.

[0076] Example 5

[0077] The composite modified flocculant in this embodiment consists of the following components by solids mass: 13.2% polyvinylammonium chloride, 20% cationic polyacrylamide, 26.6% polydimethyldiallyl ammonium chloride, and 40.2% ferric chloride. The polyvinylammonium chloride has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0078] The composite modified flocculant in this embodiment was prepared by the following method: 396 g of polyvinylamine and 600 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. 798 g of polydimethyl diallyl ammonium chloride was added to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 1206g of ferric chloride and 3.618 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0079] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 69.5%.

[0080] Example 6

[0081] The composite modified flocculant in this embodiment consists of the following components by solids mass: 8.8% polyvinylamidine, 35% cationic polyacrylamide, 30% polydimethyldiallyl ammonium chloride, and 26.2% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0082] The composite modified flocculant in this embodiment was prepared by the following method: 264g of polyvinylamine and 1050g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 900 g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 786g of ferric chloride and 2.358 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0083] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 78.2%.

[0084] Example 7

[0085] The composite modified flocculant in this embodiment consists of the following components by solids mass: 7.5% polyvinylamidine, 30% cationic polyacrylamide, 40% polydimethyldiallyl ammonium chloride, and 22.5% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0086] The composite modified flocculant in this embodiment was prepared by the following method: 225 g of polyvinylamine and 900 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 1200g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 675 g of ferric chloride and 2.97 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0087] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge is taken, and the composite modified flocculant prepared above is added. After a flocculation reaction of 180 seconds, it is dewatered by a belt dewatering machine. Using the 105°C weighing method, the sludge moisture content is reduced to 78.8%.

[0088] Example 8

[0089] The composite modified flocculant in this embodiment consists of the following components by solids mass: 12.9% polyvinylamidine, 51.4% cationic polyacrylamide, 25.7% polydimethyldiallyl ammonium chloride, and 10% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0090] The composite modified flocculant in this embodiment was prepared by the following method: 387 g of polyvinylamine and 1542 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. 771 g of polydimethyl diallyl ammonium chloride was added to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 300 g of ferric chloride and 0.9 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0091] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 74.0%.

[0092] Example 9

[0093] The composite modified flocculant in this embodiment consists of the following components by solids mass: 5.7% polyvinylamidine, 22.9% cationic polyacrylamide, 11.4% polydimethyldiallyl ammonium chloride, and 60% ferric chloride. The polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; the cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; and the polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%.

[0094] The composite modified flocculant in this embodiment was prepared by the following method: 171 g of polyvinylamine and 687 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. 342 g of polydimethyldiallyl ammonium chloride was added to deionized water in a polydimethyldiallyl ammonium chloride dissolving tank 300 to prepare a polydimethyldiallyl ammonium chloride solution with a mass fraction of 5%. 1800 g of ferric chloride and 5.4 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0095] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 75.3%.

[0096] Example 10

[0097] The composite modified flocculant in this embodiment consists of the following components by solid mass: 10% polyvinylammonium, 40% cationic polyacrylamide, 20% polydimethyldiallylammonium chloride, and 30% aluminum sulfate.

[0098] The composite modified flocculant in this embodiment was prepared by the following method: Polyvinylamidine has a molecular weight of 60,000 and a cationicity of 50%; cationic polyacrylamide has a molecular weight of 10 million and a cationicity of 45%; polydimethyldiallyl ammonium chloride has a molecular weight of 150,000 and a cationicity of 40%. 200 g of polyvinylamine and 800 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 400 g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 600 g of aluminum sulfate and 1.8 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0099] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 74.3%.

[0100] Example 11

[0101] The composite modified flocculant in this embodiment consists of the following components by solid mass: 10% polyvinylammonium, 40% cationic polyacrylamide, 20% polydimethyldiallylammonium chloride and 30% ferric chloride.

[0102] The polyvinylammonium has a molecular weight of 100,000 and a cationicity of 30%; cationic polyacrylamide has a molecular weight of 12 million and a cationicity of 30%; and polydimethyldiallyl ammonium chloride has a molecular weight of 200,000 and a cationicity of 20%. The composite modified flocculant of this embodiment was prepared by the following method: 200 g of polyvinylamine and 800 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 400 g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 600 g of ferric chloride and 1.8 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0103] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 76.6%.

[0104] Example 12

[0105] The composite modified flocculant in this embodiment consists of the following components by solid mass: 10% polyvinylammonium, 40% cationic polyacrylamide, 20% polydimethyldiallylammonium chloride and 30% ferric chloride.

[0106] The polyvinylammonium has a molecular weight of 20,000 and a cationicity of 70%; cationic polyacrylamide has a molecular weight of 8 million and a cationicity of 60%; and polydimethyldiallyl ammonium chloride has a molecular weight of 50,000 and a cationicity of 90%. The composite modified flocculant of this embodiment was prepared by the following method: 400 g of polyvinylamine and 1600 g of cationic polyacrylamide were mixed in a premixing tank 110, and then deionized water was added to prepare a mixed solution with a mass fraction of 3‰. The solution was then transferred to a curing tank and cured for 60 min. Finally, it was transferred to a storage tank 130. Add 800 g of polydimethyl diallyl ammonium chloride to deionized water in a polydimethyl diallyl ammonium chloride dissolving tank 300 to prepare a polydimethyl diallyl ammonium chloride solution with a mass fraction of 5%. 1200 g of ferric chloride and 3.6 kg of deionized water were mixed in an inorganic flocculant dissolving tank 200 to obtain an inorganic flocculant solution. Add the polydimethyldiallylammonium chloride solution to storage tank 130 and mix it with the mixed solution to obtain an organic flocculant solution; Organic and inorganic flocculant solutions are mixed in a storage tank to obtain a composite modified flocculant.

[0107] The composite modified flocculant in this embodiment is used for dewatering residual sludge from a municipal wastewater treatment plant. The residual sludge has a moisture content of 98.7%, an organic matter content of 58%, and a viscosity of 1.1 cps. One ton of this sludge was taken, and the aforementioned composite modified flocculant was added. After a flocculation reaction of 180 seconds, the sludge was dewatered using a belt dewatering machine. Using a 105°C weighing method, the sludge moisture content was reduced to 74.7%.

[0108] Comparative Example This comparative example uses cationic polyacrylamide for dewatering excess sludge from a municipal wastewater treatment plant. The excess sludge was taken from the same batch as the sludge in Example 1, with the same moisture content and organic matter content. One ton of this sludge was added with 3 kg of cationic polyacrylamide, and after 180 seconds of flocculation, it was dewatered using a belt dewatering machine. The moisture content of the sludge was reduced to 84.8% using a 105°C weighing method.

[0109] The component content and dehydration effect of Examples 1-12 and the comparative examples are summarized in Table 1 below.

[0110] Table 1. Relevant experimental parameters of Examples 1-12 and comparative examples

[0111] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0112] Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0113] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A composite modified flocculant, characterized in that, The flocculant is composed of the following components by solid mass: 1-13.2% polyvinylamine, 20-51.4% cationic polyacrylamide, 11.4-40% polydimethyldiallyl ammonium chloride and 10-60% inorganic flocculant, wherein the sum of the weight parts of polyvinylamine, cationic polyacrylamide, polydimethyldiallyl ammonium chloride and inorganic flocculant is 100%.

2. The composite modified flocculant according to claim 1, characterized in that, The flocculant is composed of the following components by solid mass: 5-13.2% polyvinylammonium, 20-40% cationic polyacrylamide, 20-30% polydimethyldiallylammonium chloride and 20-50% inorganic flocculant.

3. The composite modified flocculant according to claim 1 or 2, characterized in that, The molecular weight of the polyvinylamidine is 20,000-100,000, and the cationicity is 30%-70%.

4. The composite modified flocculant according to claim 1 or 2, characterized in that, The cationic polyacrylamide has a molecular weight of 8 million to 12 million and an ionic degree of 30 to 60%.

5. The composite modified flocculant according to claim 1 or 2, characterized in that, The polydimethyldiallylammonium chloride has a molecular weight of 50,000-200,000 and a cationicity of 20%-90%.

6. The composite modified flocculant according to claim 1 or 2, characterized in that, The inorganic flocculant is selected from at least one of polyferric sulfate, aluminum sulfate, ferric chloride, and polyaluminum chloride.

7. An apparatus for preparing the composite modified flocculant according to any one of claims 1-6, characterized in that, The system includes a three-chamber preparation module (100), an inorganic flocculant dissolving tank (200), and a polydimethyldiallyl ammonium chloride dissolving tank (300). The inorganic flocculant dissolving tank (200) is connected to the three-chamber preparation module (100) to introduce an inorganic flocculant solution into the three-chamber preparation module (100). The polydimethyldiallyl ammonium chloride dissolving tank (300) is connected to the three-chamber preparation module (100) to introduce a polydimethyldiallyl ammonium chloride solution into the three-chamber preparation module (100). The three-chamber preparation module (100) includes a premixing tank (110), a maturation tank (120), and a storage tank (130) connected in sequence.

8. A method for preparing the composite modified flocculant according to any one of claims 1-6, characterized in that, Includes the following steps: Step 100: Mix 1-13.2 parts by weight of polyvinylamidine and 20-51.4 parts by weight of cationic polyacrylamide in a three-chamber preparation module (100), add deionized water, and prepare a mixed solution with a mass fraction of 1-5‰; add 11.4-40 parts by weight of polydimethyldiallyl ammonium chloride to a polydimethyldiallyl ammonium chloride dissolving tank (300) with deionized water to prepare a polydimethyldiallyl ammonium chloride solution with a mass fraction of 5%; mix 10-60 parts by weight of inorganic flocculant with deionized water at a mass ratio of 1:2-4 in an inorganic flocculant dissolving tank (200) to dissolve and obtain an inorganic flocculant solution; Step 200: Add the polydimethyldiallylammonium chloride solution to the three-box preparation module (100) and mix it with the mixed solution to obtain an organic flocculant solution; Step 300: Mix the organic flocculant solution and the inorganic flocculant solution in a certain proportion to obtain a composite modified flocculant.

9. The method for preparing the composite modified flocculant according to claim 8, characterized in that, In step 100, the mixed solution is prepared in a premixing tank (110) and then transferred to a maturation tank (120) for maturation. In steps 200 and 300, after maturation, the mixed solution is transferred to a storage tank (130) and first mixed with the polydimethyldiallylammonium chloride solution to obtain an organic flocculant solution. Then, the organic flocculant solution is mixed with the inorganic flocculant solution to obtain a composite modified flocculant.

10. The application of the composite modified flocculant according to any one of claims 1-6 in sludge dewatering, characterized in that, Add 1-5 kg ​​of the composite modified flocculant per ton of dry sludge.

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