Sludge reduction method applied to wastewater treatment

Abstract

The invention discloses a sludge reduction method applied to wastewater treatment, belongs to the field of water treatment, and particularly relates to a method which comprises the following steps: adding a polyquaternary ammonium salt flocculating agent into water to form a flocculating liquid, and preparing a micro-nano air bag in the flocculating liquid to obtain an air bag grafted polyquaternary ammonium salt flocculating liquid; adding the air bag grafted poly quaternary ammonium salt flocculating liquid into wastewater for treatment, and separating to obtain treated water; the molar ratio of the polyquaternary ammonium salt flocculating agent to the micro-nano air bag is 1: (5-10). The sludge reduction method applied to wastewater treatment is good in COD removal effect and small in sludge amount.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and in particular relates to a sludge reduction method applied to wastewater treatment. Background Art

[0002] As more and more sewage treatment plants are put into operation in my country, sludge treatment and disposal has become a realistic challenge. In addition, the proportion of sewage treatment plants in the cost of sludge disposal is also increasing. The ultimate goal of sludge treatment is to reduce the amount of sludge from the source. The coagulation sedimentation tank is a key equipment in the sewage treatment process. It separates the suspended matter and sludge in the sewage through chemical coagulation and physical precipitation. It is also one of the important sources of sludge in sewage plants. The sludge produced by the coagulation sedimentation tank usually contains organic matter, inorganic salts, microorganisms and other components. The amount of sludge produced is also related to the type, dosage, efficiency and amount of sludge brought into the coagulant itself. In order to reduce the amount of sludge in the sewage treatment process from the source, it is possible to choose a more efficient coagulant with a lower dosage and use a physical and chemical method that does not increase the amount of sludge to improve the coagulation efficiency under the condition of achieving the same coagulation effect. Summary of the invention

[0003] The object of the present invention is to provide a sludge reduction method for wastewater treatment with good COD removal effect and small amount of sludge.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A sludge reduction method for wastewater treatment includes: adding polyquaternary ammonium salt flocculants into water to form a flocculant, preparing micro-nano airbags in the flocculant to obtain airbag-grafted polyquaternary ammonium salt flocculants; adding the airbag-grafted polyquaternary ammonium salt flocculants into wastewater for treatment, and separating to obtain treated water; the molar ratio of the polyquaternary ammonium salt flocculants to the micro-nano airbags is 1:5-10. The present invention proposes a method for sludge reduction in sewage treatment, which aims to address the defects of large dosage and high sludge production of existing commonly used coagulants, and adopts a micro-nano airbag encapsulation technology to assist polyquaternary ammonium salt flocculants to replace traditional polyaluminum or polyiron coagulants, which can greatly reduce the amount of coagulants used and the amount of subsequent sludge produced. At the same time, because metal flocculants such as polyaluminum and polyiron are not used, metal hydroxide sludge will not be produced, which improves the biodegradability of sludge biological treatment, and greatly reduces the cost of subsequent sludge treatment in terms of sludge production and difficulty.

[0005] Preferably, the polyquaternary ammonium salt flocculant includes polydimethyldiallyl ammonium chloride; or, the micro-nano air capsules are wrapped and grafted onto the side chains of the polyquaternary ammonium salt flocculant.

[0006] Preferably, the diameter of the micro-nano airbag is 200nm~50μm; or, the micro-nano airbag is produced by ultrasonic cavitation, electrode electrolysis, pressurized gas dissolution, impeller shearing, hydraulic cavitation or membrane method.

[0007] Preferably, the diameter of the micro-nano airbags that accounts for the largest volume is 40 μm; or, the micro-nano airbags are produced by hydrodynamic cavitation.

[0008] Preferably, the content of the polyquaternary ammonium salt flocculant in the flocculation liquid is 5-20wt%; or, the airbag-grafted polyquaternary ammonium salt flocculant is added to the wastewater, and the polyquaternary ammonium salt flocculant therein is measured, and the usage amount of the polyquaternary ammonium salt flocculant is 200-800ppm.

[0009] Preferably, the content of the polyquaternary ammonium salt flocculant in the flocculation liquid is 10wt%; or, the airbag-grafted polyquaternary ammonium salt flocculant is added to the wastewater, and the polyquaternary ammonium salt flocculant therein is measured, and the usage amount of the polyquaternary ammonium salt flocculant is 400ppm.

[0010] Preferably, the wastewater is printing and dyeing wastewater, sewage containing dyes or a mixture thereof.

[0011] Preferably, the molar ratio of the polyquaternary ammonium salt flocculant to the micro-nano air capsule is 1:5; or, the molar ratio of the polyquaternary ammonium salt flocculant to the micro-nano air capsule is 1:8.

[0012] The invention discloses use of airbag grafted polyquaternary ammonium salt flocculation liquid in water treatment and / or sewage treatment and / or printing and dyeing sewage. The airbag grafted polyquaternary ammonium salt flocculation liquid contains polyquaternary ammonium salt flocculants and micro-nano airbags, and the molar ratio of the polyquaternary ammonium salt flocculants to the micro-nano airbags is 1:5-10.

[0013] The invention provides a method for reducing sludge in sewage treatment, which is a sludge reduction method using a micro-nano air bag encapsulation technology to assist a polyquaternary ammonium salt flocculant.

[0014] Preferably, the polyquaternary ammonium salt flocculants include but are not limited to polydimethyldiallyl ammonium chloride flocculants.

[0015] Preferably, the initiator used in the polyquaternary ammonium salt flocculant is one of ammonium persulfate and potassium persulfate or a mixture of the two.

[0016] Preferably, after the polymerization is completed to obtain the polyquaternary ammonium salt flocculant, the reaction solution is cooled to room temperature and insoluble impurities are removed by filtration or centrifugation. A suitable organic solvent, such as methanol, ethanol, etc., is selected, the solution after polymerization is mixed and dissolved with the solvent, and then the solvent is removed and purified by distillation, evaporation, etc.

[0017] Preferably, the micro-nano airbag is a micro-nano airbag with a diameter between 200nm and 50μm; Preferably, the micro-nano airbags can be produced by ultrasonic cavitation, electrode electrolysis, pressurized dissolved air, impeller shearing, hydraulic cavitation, membrane method, etc.

[0018] Preferably, the novel coagulation and precipitation method of micro-nano air capsule grafted with polyquaternary ammonium salt flocculant is to encapsulate and graft the micro-nano air capsule onto the side chain of the polyquaternary ammonium salt flocculant, thereby increasing the charge density and adsorption capacity of the polyquaternary ammonium salt flocculant.

[0019] Preferably, in the novel coagulation and precipitation method of micro-nano air capsule grafted with polyquaternary ammonium salt flocculant, the molar ratio of polyquaternary ammonium salt to micro-nano air capsule is 1:5 to 1:10; Preferably, the novel coagulation and sedimentation method of micro-nano air capsule grafted polyquaternary ammonium salt flocculant can reduce the dosage of polyquaternary ammonium salt flocculant by 20% to 50%; Preferably, the novel coagulation and sedimentation method of micro-nano air capsule grafted with polyquaternary ammonium salt flocculant can reduce the amount of sludge in the flocculation and sedimentation process by 30% to 80%.

[0020] Preferably, in the preparation of the polydimethyldiallyl ammonium chloride flocculant, a dimethylamine solution and allyl chloride are mixed at 20-30°C, and then an alkaline reagent is added, and a reflux reaction is carried out at 30-40°C for 2-6 hours. After the reaction is completed, the product is separated, and the solid content is adjusted to 10-30%, and then the reaction is carried out at 60-80°C. Finally, an initiator is added, and the polymerization reaction is carried out for 4-6 hours. After the reaction is completed, distillation is carried out under reduced pressure to prepare the polydimethyldiallyl ammonium chloride flocculant.

[0021] More preferably, in the preparation of the polydimethyldiallylammonium chloride flocculant, the content of dimethylamine in the dimethylamine solution is 30-50 wt %.

[0022] More preferably, in the preparation of the polydimethyldiallylammonium chloride flocculant, the amount of allyl chloride used is 5-15 wt % of the dimethylamine in the dimethylamine solution.

[0023] More preferably, in the preparation of the polydimethyldiallylammonium chloride flocculant, dimethylamine in the dimethylamine solution is used for measurement, the alkaline agent is sodium hydroxide, and the amount of sodium hydroxide used is 2-6 wt % of the dimethylamine.

[0024] More preferably, in the preparation of the polydimethyldiallylammonium chloride flocculant, dimethylamine in a dimethylamine solution is used for metering, the initiator is ammonium persulfate, and the amount of the initiator used is 0.01-0.2 wt % of the dimethylamine.

[0025] Preferably, in the preparation of the airbag grafted polyquaternary ammonium salt flocculant, polydimethyldiallyl ammonium chloride flocculant is added into water to prepare the flocculant, and the micro-nano airbags are generated by hydrodynamic cavitation to form the airbag grafted polyquaternary ammonium salt flocculant.

[0026] More preferably, in the preparation of the air capsule grafted polyquaternary ammonium salt flocculant, the diameter of the micro-nano air capsule is 200 nm to 50 μm.

[0027] More preferably, in the preparation of the airbag grafted polyquaternary ammonium salt flocculant, the content of the polydimethyldiallyl ammonium chloride flocculant in the airbag grafted polyquaternary ammonium salt flocculant is 5-20wt%.

[0028] More preferably, in the preparation of the air capsule grafted polyquaternary ammonium salt flocculant, the molar ratio of the micro-nano air capsule and the polydimethyldiallyl ammonium chloride flocculant is 1:5-10, and the micro-nano air capsule is wrapped and grafted onto the side chain of the polyquaternary ammonium salt flocculant, thereby increasing the charge density and adsorption capacity of the polyquaternary ammonium salt flocculant.

[0029] More preferably, in the preparation of the airbag grafted polyquaternary ammonium salt flocculant, the polyquaternary ammonium salt flocculant includes polydimethyldiallyl ammonium chloride flocculant. The micro-nano airbag is prepared by hydrodynamic cavitation, and the diameter of the obtained micro-nano airbag is concentrated in the range of 200nm~50μm.

[0030] Preferably, in the treatment of wastewater, the pH of the printing and dyeing wastewater is adjusted to neutral, and the airbag grafted polyquaternary ammonium salt flocculant is added, stirred for 2 to 10 minutes, left to stand for 10 to 60 minutes, and the sediment is separated to obtain treated water.

[0031] More preferably, in the treatment of wastewater, the pH adjuster includes calcium hydroxide, sodium hydroxide or potassium hydroxide.

[0032] More preferably, in the treatment of wastewater, the amount of the airbag grafted polyquaternary ammonium salt flocculant used is 1-4 vol% of the printing and dyeing wastewater.

[0033] The present invention utilizes the high specific surface area and strong charge of micro-nano airbags, encapsulates and grafts them onto the side chains of polyquaternary ammonium salt flocculants, can improve the charge density and adsorption of polyquaternary ammonium salt flocculants, improve flocculation speed and efficiency, and greatly reduce the dosage of flocculants under the same flocculation effect. Compared with traditional polyaluminum or polyiron coagulants, the dosage of the method of the present invention can be reduced by 20-50%, and the corresponding sludge production in the wastewater process is lower, and the treatment cost is lower. Therefore, the present invention is a sludge reduction method for wastewater treatment with good COD removal effect and less sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is an infrared spectrum.

[0035] Figure 2 Schematic diagram of micro-nano air capsules encapsulated and grafted onto polyquaternary ammonium salt flocculants. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0038] Example 1: A sludge reduction method for wastewater treatment Preparation of polydimethyldiallyl ammonium chloride flocculant: dimethylamine solution and allyl chloride are mixed at 25°C, then an alkaline reagent is added, and a reflux reaction is carried out at 35°C for 4 hours. After the reaction is completed, the product is separated, the solid content is adjusted to 20%, and then the reaction is carried out at 70°C. Finally, an initiator is added, and the polymerization reaction is carried out for 5 hours. After the reaction is completed, the polydimethyldiallyl ammonium chloride flocculant is prepared by vacuum distillation. The content of dimethylamine in the dimethylamine solution is 35wt%, and the amount of allyl chloride used is 8wt% of dimethylamine based on the dimethylamine in the dimethylamine solution. The alkaline reagent is sodium hydroxide, and the amount of sodium hydroxide used is 4wt% of dimethylamine. The initiator is ammonium persulfate, and the amount of the initiator used is 0.1wt% of dimethylamine.

[0039] Preparation of airbag grafted polyquaternary ammonium salt flocculant: polydimethyldiallyl ammonium chloride flocculant is added to water to prepare flocculant, micro-nano airbags are generated by hydrodynamic cavitation, and airbag grafted polyquaternary ammonium salt flocculant is compounded. The diameter of micro-nano airbags is 200nm~50μm, the content of polydimethyldiallyl ammonium chloride flocculant in airbag grafted polyquaternary ammonium salt flocculant is 10wt%, the molar ratio of micro-nano airbags to polydimethyldiallyl ammonium chloride flocculant is 1:5, and micro-nano airbags are wrapped and grafted onto the side chain of polyquaternary ammonium salt flocculant, which increases the charge density and adsorption capacity of polyquaternary ammonium salt flocculant. Polyquaternary ammonium salt flocculants include polydimethyldiallyl ammonium chloride flocculants. Micro-nano airbags are prepared by hydrodynamic cavitation, and the diameter of the obtained micro-nano airbags is concentrated in the range of 200nm~50μm.

[0040] Wastewater treatment: adjust the pH of the printing and dyeing wastewater to neutral, add airbag grafted polyquaternary ammonium salt flocculant, stir for 2 minutes, let stand for 20 minutes, separate the sediment, and obtain treated water. The pH adjuster includes calcium hydroxide, sodium hydroxide or potassium hydroxide. The amount of airbag grafted polyquaternary ammonium salt flocculant is 2vol% of the printing and dyeing wastewater. The COD of the printing and dyeing wastewater is 500mg / L, the chromaticity is 2500, and the COD removal rate after treatment with the airbag grafted polyquaternary ammonium salt flocculant is 95%.

[0041] According to the method of Example 1, polydimethyldiallyl ammonium chloride flocculant was added into water to prepare flocculant solution without grafting micro-nano air capsules. When the COD removal rate reached 95%, 2.5 vol% flocculant solution was required, and the sludge volume increased by 35% accordingly.

[0042] The infrared spectrum of the polydimethyldiallyl ammonium chloride flocculant prepared in Example 1 of the present invention is as follows: Figure 1 As shown, at 1262 cm ~1 , 1126 cm ~1 and 678 cm ~1 , three strong absorption peaks appear at 1262cm ~1 The absorption peak at 678 cm is caused by the stretching vibration of the C~N bond in the five-membered heterocyclic ring of carbon and hydrogen. ~1 The absorption peak at is caused by the deformation vibration of the bond. After DMDAAC is homopolymerized to form PDMDAAC, the double bond in the vinyl structure no longer exists, forming a long-chain polymer containing a carbon-nitrogen five-membered heterocycle. Copolymer 3017cm ~1 The absorption peak at 964cm is caused by the stretching vibration of the carbon-hydrogen bond on the methylene group connected to nitrogen in the carbon-nitrogen five-membered heterocyclic ring. ~1 The absorption peak at is caused by the deformation vibration of the bond.

[0043] Comparative Example 1: A sludge reduction method for wastewater treatment The difference between this comparative example and Example 1 lies in the preparation of the air-capsule grafted polyquaternary ammonium salt flocculant.

[0044] Preparation of airbag grafted polyquaternary ammonium salt flocculant: polydimethyldiallyl ammonium chloride flocculant is added to water to prepare flocculant, micro-nano airbags are generated by hydrodynamic cavitation, and airbag grafted polyquaternary ammonium salt flocculant is compounded. The diameter of micro-nano airbags is 200nm~50μm, the content of polydimethyldiallyl ammonium chloride flocculant in airbag grafted polyquaternary ammonium salt flocculant is 10wt%, the molar ratio of micro-nano airbags to polydimethyldiallyl ammonium chloride flocculant is 1:3, and micro-nano airbags are wrapped and grafted onto the side chain of polyquaternary ammonium salt flocculant, which increases the charge density and adsorption capacity of polyquaternary ammonium salt flocculant. Polyquaternary ammonium salt flocculants include polydimethyldiallyl ammonium chloride flocculants. Micro-nano airbags are prepared by hydrodynamic cavitation, and the diameter of the obtained micro-nano airbags is concentrated in the range of 200nm~50μm.

[0045] Comparative Example 2: A sludge reduction method for wastewater treatment The difference between this comparative example and Example 1 lies in the preparation of the air-capsule grafted polyquaternary ammonium salt flocculant.

[0046] Preparation of airbag grafted polyquaternary ammonium salt flocculant: polydimethyldiallyl ammonium chloride flocculant is added to water to prepare flocculant, micro-nano airbags are generated by hydrodynamic cavitation, and airbag grafted polyquaternary ammonium salt flocculant is compounded. The diameter of micro-nano airbags is 200nm~50μm, the content of polydimethyldiallyl ammonium chloride flocculant in airbag grafted polyquaternary ammonium salt flocculant is 10wt%, the molar ratio of micro-nano airbags to polydimethyldiallyl ammonium chloride flocculant is 1:12, and micro-nano airbags are wrapped and grafted onto the side chain of polyquaternary ammonium salt flocculant, which increases the charge density and adsorption capacity of polyquaternary ammonium salt flocculant. Polyquaternary ammonium salt flocculants include polydimethyldiallyl ammonium chloride flocculants. Micro-nano airbags are prepared by hydrodynamic cavitation, and the diameter of the obtained micro-nano airbags is concentrated in the range of 200nm~50μm.

[0047] The technical solutions of Comparative Examples 1 to 2 in the present invention are not as good as the technical solution of Example 1 in treating printing and dyeing wastewater, and the molar ratio of the micro-nano airbags and the polydimethyldiallyl ammonium chloride flocculant is controlled within the range of 1:5-10, which has better economic efficiency.

[0048] The schematic diagram of the micro-nano air capsule encapsulated and grafted to the polyquaternary ammonium salt flocculant in the present invention is as follows Figure 2 As shown, grafting refers to the reaction of combining appropriate side chains or functional side groups on the macromolecular chain through chemical bonds. Figure 2It is also expressed in the form of charge adsorption. The reason why the present invention uses grafting to describe it is that the micro-nano airbags, especially when they reach the nanometer level, will become an unstable and high-energy state with high surface energy. The process of combining with the polymer flocculant is not a simple charge adsorption, but is closer to valence bond bonding, so it is called grafting.

[0049] Example 2: A sludge reduction method for wastewater treatment Preparation of polydimethyldiallyl ammonium chloride flocculant: dimethylamine solution and allyl chloride are mixed at 25°C, then an alkaline reagent is added, and a reflux reaction is carried out at 30°C for 4 hours. After the reaction is completed, the product is separated, the solid content is adjusted to 20%, and then the reaction is carried out at 70°C. Finally, an initiator is added, and the polymerization reaction is carried out for 5 hours. After the reaction is completed, reduced pressure distillation is carried out to prepare polydimethyldiallyl ammonium chloride flocculant. The content of dimethylamine in the dimethylamine solution is 45wt%, and the amount of allyl chloride used is 11wt% of dimethylamine based on the dimethylamine in the dimethylamine solution. The alkaline reagent is sodium hydroxide, and the amount of sodium hydroxide used is 4wt% of dimethylamine. The initiator is ammonium persulfate, and the amount of the initiator used is 0.1wt% of dimethylamine.

[0050] Preparation of airbag grafted polyquaternary ammonium salt flocculant: polydimethyldiallyl ammonium chloride flocculant is added to water to prepare flocculant, micro-nano airbags are generated by hydrodynamic cavitation, and airbag grafted polyquaternary ammonium salt flocculant is compounded. The diameter of micro-nano airbags is 200nm~50μm, the content of polydimethyldiallyl ammonium chloride flocculant in airbag grafted polyquaternary ammonium salt flocculant is 10wt%, the molar ratio of micro-nano airbags to polydimethyldiallyl ammonium chloride flocculant is 1:8, and micro-nano airbags are wrapped and grafted onto the side chain of polyquaternary ammonium salt flocculant, which increases the charge density and adsorption capacity of polyquaternary ammonium salt flocculant. Polyquaternary ammonium salt flocculants include polydimethyldiallyl ammonium chloride flocculants. Micro-nano airbags are prepared by hydrodynamic cavitation, and the diameter of the obtained micro-nano airbags is concentrated in the range of 200nm~50μm.

[0051] Wastewater treatment: adjust the pH of the printing and dyeing wastewater to neutral, add the airbag grafted polyquaternary ammonium salt flocculant, stir for 2 minutes, let stand for 20 minutes, separate the sediment, and obtain treated water. The pH adjuster includes calcium hydroxide, sodium hydroxide or potassium hydroxide. The amount of airbag grafted polyquaternary ammonium salt flocculant is 2.5vol% of the printing and dyeing wastewater. The COD of the printing and dyeing wastewater is 500mg / L, the chromaticity is 2500, and the COD removal rate after adding the airbag grafted polyquaternary ammonium salt flocculant is 91.3%.

[0052] According to the method of Example 2, polydimethyldiallyl ammonium chloride flocculant was added into water to prepare flocculant solution without grafting micro-nano air capsules. When the COD removal rate reached 91.3%, 4.5 vol% flocculant solution was required, and the sludge volume increased by 45% accordingly.

[0053] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention.

[0054] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A sludge reduction method for wastewater treatment, comprising: A polyquaternary ammonium salt flocculant is added into water to form a flocculant, and micro-nano air capsules are prepared in the flocculant to obtain an air capsule grafted polyquaternary ammonium salt flocculant; The airbag grafted polyquaternary ammonium salt flocculant is added into wastewater for treatment, and the treated water is obtained by separation; the molar ratio of the polyquaternary ammonium salt flocculant to the micro-nano airbag is 1:5-10.

2. A sludge reduction method for wastewater treatment according to claim 1, characterized in that: The polyquaternary ammonium salt flocculant includes polydimethyldiallyl ammonium chloride; or, the micro-nano air capsules are wrapped and grafted onto the side chains of the polyquaternary ammonium salt flocculant.

3. A sludge reduction method for wastewater treatment according to claim 1, characterized in that: The diameter of the micro-nano airbag is 200nm~50μm; or, the micro-nano airbag is produced by ultrasonic cavitation, electrode electrolysis, pressurized gas dissolution, impeller shearing, hydraulic cavitation or membrane method.

4. A sludge reduction method for wastewater treatment according to claim 3, characterized in that: The diameter of the micro-nano airbags that accounts for the largest volume is 40 μm; or, the micro-nano airbags are produced by hydrodynamic cavitation.

5. A sludge reduction method for wastewater treatment according to claim 1, characterized in that: The content of the polyquaternary ammonium salt flocculant in the flocculation liquid is 5-20wt%; or, the airbag grafted polyquaternary ammonium salt flocculant is added to the wastewater, and the polyquaternary ammonium salt flocculant is measured, and the usage amount of the polyquaternary ammonium salt flocculant is 200-800ppm.

6. A sludge reduction method for wastewater treatment according to claim 5, characterized in that: The content of the polyquaternary ammonium salt flocculant in the flocculation liquid is 10wt%; or, the airbag grafted polyquaternary ammonium salt flocculant is added to the wastewater, and the polyquaternary ammonium salt flocculant is measured, and the usage amount of the polyquaternary ammonium salt flocculant is 400ppm.

7. The sludge reduction method for wastewater treatment according to claim 1, characterized in that: The wastewater is printing and dyeing wastewater, sewage containing dyes or a mixture thereof.

8. A sludge reduction method for wastewater treatment according to any one of claims 1 to 7, characterized in that: The molar ratio of the polyquaternary ammonium salt flocculant to the micro-nano air capsule is 1:5; or, the molar ratio of the polyquaternary ammonium salt flocculant to the micro-nano air capsule is 1:

8.

9. Use of air-bag grafted polyquaternary ammonium salt flocculant in water treatment and / or sewage treatment and / or printing and dyeing sewage, wherein the air-bag grafted polyquaternary ammonium salt flocculant contains polyquaternary ammonium salt flocculant and micro-nano air bags.

10. The use according to claim 9, characterized in that: The molar ratio of the polyquaternary ammonium salt flocculant to the micro-nano air capsule is 1:5-10.

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