Method for treating sewage generated in cage rough washing process

Abstract

The invention discloses a method for treating sewage generated by a cage rough washing process, and belongs to the technical field of industrial sewage treatment. Sewage generated in a cage rough washing process is subjected to first-time filter pressing after being treated by polyacrylamide and polyaluminum chloride, then a flocculating agent and water are mixed and put into a liquid medicine cylinder, the agent and the sewage in the liquid medicine cylinder are synchronously conveyed into a stirring cylinder for first-time stirring, then an oil removing agent is added, and second-time stirring is continued; and carrying out secondary filter pressing on the treated water, feeding the water into a precipitation cylinder, finally adding an oxidizing agent, and standing to obtain the treated water. According to the method, by adding polyacrylamide, polyaluminum chloride, a flocculating agent and a deoiling agent, metal ions, oily components and other impurities in sewage generated in the rough washing process are rapidly removed, the impurity content and the COD value in the sewage are reduced, the treated water can be applied to the rough washing process again, and the utilization rate of water resources is increased.

Description

Technical Field

[0001] This application relates to a method for treating wastewater generated during the cage rough washing process, belonging to the field of industrial wastewater treatment technology. Background Technology

[0002] In the bearing and precision machinery manufacturing industry, cages are key components that undergo multiple processes during their manufacturing. The rough cleaning process is a crucial step, primarily used to remove oil, metal shavings, polishing paste, rust-preventive oil, and some solid particles remaining on the workpiece surface after stamping and heat treatment. This process typically uses industrial cleaning agents containing surfactants, resulting in cage rough cleaning wastewater with a complex composition and high treatment difficulty. Oily substances are stable in an emulsion state with water under the action of surfactants, making effective separation difficult using only gravity sedimentation or traditional oil separators. Furthermore, the cleaning agent itself, dissolved oils, and fine metal particles lead to increased COD values ​​in the wastewater, causing severe eutrophication and physical pollution of water bodies. In addition, high concentrations of surfactants and mineral oils have inhibitory or even toxic effects on microorganisms, and oily substances are difficult for microorganisms to directly degrade, making conventional biological treatment methods inefficient.

[0003] Existing technologies typically require large amounts of demulsifiers and flocculants to achieve the desired treatment effect, increasing treatment costs and generating large quantities of oily chemical sludge, leading to even higher subsequent sludge disposal costs. While ultrafiltration or microfiltration membranes can effectively trap oil droplets and particles, these membranes foul rapidly, require frequent cleaning, and have high operation and maintenance costs; furthermore, the resulting concentrate still requires further treatment.

[0004] Therefore, there is an urgent need for a wastewater treatment method that is efficient, economical, stable, and easy to control. Summary of the Invention

[0005] To address the aforementioned issues, a wastewater treatment method for the cage pre-washing process is provided. This method rapidly removes impurities such as metal ions and oily components from the wastewater generated by the pre-washing process by adding polyacrylamide, polyaluminum chloride, flocculants, and degreasing agents. This reduces the impurity content and COD value of the wastewater, allowing the treated water to be reused in the pre-washing process and improving water resource utilization.

[0006] One aspect of this application provides a method for treating wastewater generated during a cage pre-washing process, comprising the following steps: (1) After adding polyacrylamide and polyaluminum chloride to the wastewater generated by the cage coarse washing process, the wastewater is stirred and then subjected to the first pressure filtration to remove larger particulate impurities in the wastewater. (2) The pretreated sewage in step (1) is transported to the sewage tank. The flocculant is mixed with water to obtain flocculant solution, which is then loaded into the solution tank. The flocculant solution and sewage are then transported to the mixing tank simultaneously. The first stirring is carried out in the mixing tank. Then, the degreasing agent is added to the mixing tank for the second stirring. (3) After the water treated in step (2) is filtered for the second time, it is transported to the sedimentation tank. An oxidant is added to the sedimentation tank and the treated water is obtained after standing.

[0007] Polyacrylamide and polyaluminum chloride are added to the wastewater generated by the coarse washing process. Polyaluminum chloride rapidly hydrolyzes in water to generate polynuclear hydroxy complexes and aluminum hydroxide colloids. Through adsorption bridging and charge neutralization, it can initially adsorb suspended impurities such as aluminum fragments and some emulsified oil droplets in the wastewater, causing the fine impurities suspended in the wastewater to form tiny flocs. Polyacrylamide has a long molecular chain length and a large specific surface area. It can entangle the tiny flocs through adsorption bridging, promote floc aggregation and growth, and improve the settling speed and strength of the flocs. In addition, polyacrylamide can demulsify the emulsion system formed in the wastewater.

[0008] Polyacrylamide and polyaluminum chloride work synergistically to efficiently remove suspended impurities, metal ions, and emulsified oil droplets from water, improving COD and turbidity removal rates. Polyaluminum chloride first adsorbs metal ions, metal debris, and suspended impurities in wastewater to form micro-flocs. Then, polyacrylamide wraps around the micro-flocs, promoting floc aggregation and growth, which facilitates subsequent removal, improves wastewater treatment efficiency, effectively reduces the impurity content in wastewater, and makes wastewater easier to recycle.

[0009] Optionally, the mass ratio of polyacrylamide to polyaluminum chloride is 1:(1-2).

[0010] At this ratio, the dosage of polyaluminum chloride can fully meet the charge neutralization requirements of colloidal particles, while polyacrylamide can rapidly link flocs to form larger flocs, increasing floc settling speed and improving wastewater treatment efficiency. The synergistic effect of both can initially adsorb and link most suspended solids, and the larger linked flocs are removed through the first pressure filtration, reducing impurities in the wastewater.

[0011] Optionally, the total addition amount of polyacrylamide and polyaluminum chloride is 50-60 g / m³. 3 .

[0012] At this dosage, it can effectively adsorb and bind metal ions and suspended solids in wastewater, effectively removing impurities. However, if the dosage of polyacrylamide and polyaluminum chloride is too high, it will not only increase the cost of wastewater treatment, but may also result in a large amount of reagent residue in the wastewater, thus affecting the wastewater treatment effect.

[0013] Optionally, the flocculant, by mass fraction, comprises: 40-50 parts of polyferric sulfate, 5-10 parts of chitosan quaternary ammonium salt, and 5-10 parts of sodium polyacrylate.

[0014] Wastewater pretreated with polyacrylamide and polyaluminum chloride contains small-sized and highly dispersed metal ions and suspended solids. A single flocculant is insufficient to effectively remove these impurities. The synergistic effect of polyferric sulfate, chitosan quaternary ammonium salt, and sodium polyacrylate effectively adsorbs these minute and highly dispersed impurities. The highly positively charged polynuclear hydroxy iron complex generated by the hydrolysis of polyferric sulfate rapidly neutralizes negatively charged suspended solids and organic colloids in the wastewater, disrupting their stability and forming tiny flocs. The quaternary ammonium groups in chitosan quaternary ammonium salt carry a strong positive charge, further enhancing the charge neutralization effect, while its molecular chains adsorb onto the surface of these tiny flocs. The ultra-long molecular chains of sodium polyacrylate adsorb a large number of floc particles, bridging them into large, high-density flocs, which are then removed by a second pressure filtration, reducing the COD, suspended solids content, and turbidity of the treated water.

[0015] Optionally, the amount of degreasing agent added is 10-15 g / m³. 3 .

[0016] Optionally, the method for preparing the degreasing agent includes the following steps: S1: Biomass is treated in an inert atmosphere at 500-600℃ to obtain biomass precursors; S2: Add biomass precursor to water, then add ferric chloride hexahydrate and ferrous chloride tetrahydrate, stir thoroughly, then add ammonia under inert gas protection to adjust the pH to 9.5-10.5, react at 70-80°C for 1-2 hours, wash until neutral, magnetically separate and dry to obtain intermediate A. S3: Add intermediate A to water, disperse evenly, add long-chain alkyl quaternary ammonium salt, mix and stir at 60-80°C for 4-8 hours, wash, magnetically separate and dry to obtain degreasing agent.

[0017] By carbonizing biomass at high temperatures to generate a large number of oxide groups on its surface, a co-precipitation reaction is carried out with ferric chloride hexahydrate and ferrous chloride tetrahydrate. The resulting magnetic intermediate A is obtained by separation using a permanent magnet. When intermediate A is dispersed in water, the -COOH and phenolic hydroxyl groups in intermediate A ionize in water, forming negatively charged active sites. The long-chain alkyl quaternary ammonium salt ionizes in water to release positively charged long-chain alkyl quaternary ammonium ions. These positively charged quaternary ammonium ions are electrostatically attracted to the negatively charged active sites on the surface of intermediate A, thereby grafting the long-chain alkyl groups onto the surface of intermediate A. The hydrophobic long carbon chains can adsorb oil molecules in the water through hydrophobic interactions, achieving an oil removal effect. At the same time, the magnetic properties of Fe3O4 enable separation and recovery.

[0018] Optionally, the mass fraction of ammonia water is 20%.

[0019] Optionally, the long-chain alkyl quaternary ammonium salt is selected from at least one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride.

[0020] Optionally, the biomass mentioned in step S1 is one of straw, sawdust, and rice husk.

[0021] Optionally, the high-temperature treatment time in step S1 is 1-1.5 hours.

[0022] Optionally, the mass ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate is 1:(1.5-2.5).

[0023] At this ratio, Fe² + Under alkaline conditions, it is easily oxidized to Fe³ by oxygen in the air. + Excess Fe² + It can preferentially react with oxygen, reducing Fe² in the target reaction. + Consumption, excess Fe² + More active sites can be formed on the surface of biomass precursors, promoting the in-situ growth of Fe3O4 crystals in its porous structure, making the bond between magnetic particles and biochar stronger, and preventing the magnetic components from falling off during subsequent use. At the same time, Fe3O4 has a large specific surface area and strong adsorption capacity, which can effectively adsorb metal ions in wastewater, further improving the treatment effect.

[0024] Preferably, the mass ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate is 1:2.

[0025] Optionally, the mass ratio of the biomass precursor, ferric chloride hexahydrate, and ferrous chloride tetrahydrate is 1:(0.2-0.3):(0.5-0.8).

[0026] At this ratio, ferric chloride hexahydrate and ferrous chloride tetrahydrate undergo a co-precipitation reaction to form iron(III) oxide, which makes it more tightly bound to the biomass precursor, reduces the probability of shedding, improves the magnetism of the degreasing agent, and facilitates subsequent recycling.

[0027] Optionally, the mass ratio of the biomass precursor to the long-chain alkyl quaternary ammonium salt is 1:(8-10).

[0028] At this ratio, long-chain alkyl groups can be grafted onto intermediate A to the maximum extent, and the hydrophobic long carbon chains can adsorb oil molecules in water through hydrophobic interactions, thereby achieving an oil removal effect.

[0029] The beneficial effects of this application include, but are not limited to: 1. The wastewater treatment method for the cage pre-washing process according to this application can quickly remove impurities such as metal ions and oily components from the wastewater generated by the pre-washing process, reduce the impurity content and COD value in the wastewater, and enable the treated water to be reused in the pre-washing process, thereby improving the utilization rate of water resources.

[0030] 2. The wastewater treatment method for the cage rough washing process according to this application can quickly disrupt the stability of the oil-in-water emulsion through pretreatment, causing the emulsified oil droplets to coalesce and separate, while efficiently removing suspended impurities such as aluminum fragments and aluminum hydroxide colloids from the water. Then, a flocculant is added to further remove metal ions and impurities from the wastewater, thereby improving the turbidity removal rate.

[0031] 3. The wastewater treatment method based on the cage rough washing process of this application, by adding degreasing agent and flocculant in synergy, fully adsorbs and demulsifies the highly dispersed metal ions and the difficult-to-demulsify emulsion system in the wastewater, so that the treated water can be directly discharged or recycled, thereby improving the utilization rate of water resources.

[0032] 4. The wastewater treatment method generated by the cage rough washing process according to this application is simple and convenient, has a good wastewater treatment effect, and uses low-cost raw materials. It is suitable for the continuous operation needs of industrial production lines, takes into account both treatment efficiency and economy, and reduces the unit wastewater treatment cost. Detailed Implementation

[0033] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0034] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0035] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0036] The filter press model used in this application is not specifically limited, as long as it can achieve the filtration of wastewater. In the following embodiments and comparative examples of this application, the feed pressure of the filter press for both primary and secondary filtration is 8 kg / cm². 2 The pressing pressure was 12 kg / cm². 2 The blowing pressure is 12 kg / cm². 2 The air permeability of the filter cloth is 30 L / m. 2 / s, and the pressing time is 5min.

[0037] In the embodiments and comparative examples of this application, the sodium polyacrylate is anionic sodium polyacrylate with a molecular weight of 20 million and an ionic degree of 30%; the polyacrylamide is cationic polyacrylamide with a molecular weight of 8 million and an ionic degree of 20%; and the chitosan quaternary ammonium salt has a molecular weight of 2 × 10⁻⁶. 5 -3×10 5 The degree of substitution is 80%; the CAS number for polyaluminum chloride is 101707-17-9; the CAS number for polyferric sulfate is 35139-28-7; the CAS number for ferric chloride hexahydrate is 10025-77-1; the CAS number for ferrous chloride tetrahydrate is 13478-10-9; the CAS number for tetradecyltrimethylammonium chloride is 4574-04-3; the CAS number for octadecyltrimethylammonium chloride is 112-03-8; the CAS number for ammonium chloride is 112-02-7; the CAS number for ammonium chloride is 12125-02-9; and the CAS number for ammonium persulfate is 7727-54-0.

[0038] Example 1 This application relates to a method for treating wastewater generated during the cage pre-washing process, comprising the following steps: (1) After adding polyacrylamide and polyaluminum chloride to the wastewater generated from the cage rough washing process, the mass ratio of polyacrylamide to polyaluminum chloride is 1:1, and the total addition amount of polyacrylamide and polyaluminum chloride is controlled to be 50 g / m 3 The mixture was stirred at a speed of 60 r / min for 20 min. After stirring, the mixture was filtered for the first time to remove larger particles of impurities from the wastewater. (2) The pretreated wastewater from step (1) is transported to a wastewater tank. The flocculant is mixed with 20 times the amount of water to obtain a flocculant solution, which is then placed in a solution tank. The flocculant solution and wastewater are then simultaneously transported to a mixing tank for the first stirring. The mixing is performed at a stirring speed of 50 r / min for 15 min. After that, an oil remover is added to the mixing tank, and the amount of oil remover added is controlled to be 10 g / m³. 3 Then, perform a second stirring at a stirring speed of 50 r / min for 15 min; The flocculant, by mass fraction, comprises: 40 parts polyferric sulfate, 10 parts chitosan quaternary ammonium salt, and 5 parts sodium polyacrylate; The preparation method of the degreasing agent includes the following steps: S1: The pulverized material is placed in a tube furnace and heated to 500°C under a nitrogen atmosphere, and held for 1.5 hours; then cooled to room temperature under nitrogen protection to obtain the biomass precursor. S2: Add the biomass precursor to 8 times the amount of water and treat it with an ultrasonic cleaner at 100W for 15 minutes. Then add ferric chloride hexahydrate and ferrous chloride tetrahydrate. The mass ratio of biomass precursor, ferric chloride hexahydrate and ferrous chloride tetrahydrate is 1:0.2:0.5. Stir thoroughly. Then, under nitrogen protection, add 20% ammonia water to adjust the pH to 9.5. React at 70°C for 2 hours. Cool to room temperature, and use a permanent magnet to magnetically separate the product. Wash with 50% ethanol aqueous solution until neutral. After drying, grind and pass through a 60-mesh sieve to obtain intermediate A. S3: Add intermediate A to 50 times the amount of water, treat it with an ultrasonic cleaner at 150w for 15 minutes, disperse it evenly, add tetradecyltrimethylammonium chloride, the amount of tetradecyltrimethylammonium chloride added is 8 times the amount of biomass precursor, mix and stir at 60°C for 8 hours, cool to room temperature, separate the product with a permanent magnet, wash it 3 times with deionized water, vacuum dry it, grind it, and pass it through a 60-mesh sieve to obtain the degreasing agent; (3) After the water treated in step (2) is filtered a second time, it is transported to a sedimentation tank. Sodium hypochlorite is added to the sedimentation tank, and the addition of sodium hypochlorite is controlled at 0.1 g / m³. 3 After standing for 1 hour, the treated water is obtained.

[0039] Example 2 This application relates to a method for treating wastewater generated during the cage pre-washing process, comprising the following steps: (1) After adding polyacrylamide and polyaluminum chloride to the wastewater generated from the cage rough washing process, the mass ratio of polyacrylamide to polyaluminum chloride is 1:2, and the total addition amount of polyacrylamide and polyaluminum chloride is controlled to be 60 g / m 3 The mixture was stirred at a speed of 60 r / min for 20 min. After stirring, the mixture was filtered for the first time to remove larger particles of impurities from the wastewater. (2) The pretreated wastewater from step (1) is transported to a wastewater tank. The flocculant is mixed with 20 times the amount of water to obtain a flocculant solution, which is then placed in a solution tank. The flocculant solution and wastewater are then simultaneously transported to a mixing tank for the first stirring. The mixing is performed at a stirring speed of 50 r / min for 15 min. After that, an oil remover is added to the mixing tank, and the amount of oil remover added is controlled to be 15 g / m³.3 Then, perform a second stirring at a stirring speed of 50 r / min for 15 min; The flocculant, by mass fraction, comprises: 50 parts of polyferric sulfate, 5 parts of chitosan quaternary ammonium salt, and 10 parts of sodium polyacrylate; The preparation method of the degreasing agent includes the following steps: S1: The pulverized material is placed in a tube furnace and heated to 600°C under a nitrogen atmosphere, and held for 1 hour; then cooled to room temperature under nitrogen protection to obtain the biomass precursor. S2: Add the biomass precursor to 8 times the amount of water and treat it with an ultrasonic cleaner at 100W for 15 minutes. Then add ferric chloride hexahydrate and ferrous chloride tetrahydrate. The mass ratio of biomass precursor, ferric chloride hexahydrate and ferrous chloride tetrahydrate is 1:0.3:0.8. Stir thoroughly. Then, under nitrogen protection, add 20% ammonia water to adjust the pH to 10.5. React at 80°C for 1 hour. Cool to room temperature, and use a permanent magnet to magnetically separate the product. Wash with 50% ethanol aqueous solution until neutral. After drying, grind and pass through a 60-mesh sieve to obtain intermediate A. S3: Add intermediate A to 50 times the amount of water, treat it with an ultrasonic cleaner at 150w for 15 minutes, disperse it evenly, add octadecyltrimethylammonium chloride, the amount of octadecyltrimethylammonium chloride added is 10 times the amount of biomass precursor, mix and stir at 80°C for 4 hours, cool to room temperature, separate the product with a permanent magnet, wash it 3 times with deionized water, vacuum dry it, grind it, and pass it through a 60-mesh sieve to obtain the degreasing agent; (3) After the water treated in step (2) is filtered a second time, it is transported to a sedimentation tank. Sodium hypochlorite is added to the sedimentation tank, and the addition of sodium hypochlorite is controlled at 0.1 g / m³. 3 After standing for 1 hour, the treated water is obtained.

[0040] Example 3 This application relates to a method for treating wastewater generated during the cage pre-washing process, comprising the following steps: (1) After adding polyacrylamide and polyaluminum chloride to the wastewater generated from the cage rough washing process, the mass ratio of polyacrylamide to polyaluminum chloride is 1:1.5, and the total addition amount of polyacrylamide and polyaluminum chloride is controlled to be 55 g / m 3 The mixture was stirred at a speed of 60 r / min for 20 min. After stirring, the mixture was filtered for the first time to remove larger particles of impurities from the wastewater. (2) The pretreated wastewater from step (1) is transported to a wastewater tank. The flocculant is mixed with 20 times the amount of water to obtain a flocculant solution, which is then placed in a solution tank. The flocculant solution and wastewater are then simultaneously transported to a mixing tank for the first stirring. The mixing is performed at a stirring speed of 50 r / min for 15 min. After that, an oil remover is added to the mixing tank, and the amount of oil remover added is controlled to be 12 g / m³. 3 Then, perform a second stirring at a stirring speed of 50 r / min for 15 min; The flocculant, by mass fraction, comprises: 45 parts polyferric sulfate, 8 parts chitosan quaternary ammonium salt, and 8 parts sodium polyacrylate; The preparation method of the degreasing agent includes the following steps: S1: The pulverized material is placed in a tube furnace and heated to 550°C under a nitrogen atmosphere, and held for 1.2 hours; then cooled to room temperature under nitrogen protection to obtain the biomass precursor. S2: Add the biomass precursor to 8 times the amount of water and treat it with an ultrasonic cleaner at 100W for 15 minutes. Then add ferric chloride hexahydrate and ferrous chloride tetrahydrate. The mass ratio of biomass precursor, ferric chloride hexahydrate and ferrous chloride tetrahydrate is 1:0.25:0.6. Stir thoroughly. Then, under nitrogen protection, add 20% ammonia water to adjust the pH to 10. React at 70°C for 1.5 hours. Cool to room temperature, and use a permanent magnet to magnetically separate the product. Wash with 50% ethanol aqueous solution until neutral. After drying, grind and pass through a 60-mesh sieve to obtain intermediate A. S3: Add intermediate A to 50 times the amount of water, treat it with an ultrasonic cleaner at 150w for 15 minutes, disperse it evenly, add hexadecyltrimethylammonium chloride, the amount of hexadecyltrimethylammonium chloride added is 9 times the amount of biomass precursor, mix and stir at 70°C for 6 hours, cool to room temperature, separate the product with a permanent magnet, wash with water 3 times, vacuum dry, grind, and pass through a 60-mesh sieve to obtain the degreasing agent; (3) After the water treated in step (2) is filtered a second time, it is transported to a sedimentation tank. Sodium hypochlorite is added to the sedimentation tank, and the addition of sodium hypochlorite is controlled at 0.1 g / m³. 3 After standing for 1 hour, the treated water is obtained.

[0041] Example 4 The difference between this embodiment and embodiment 3 is that the mass ratio of polyacrylamide to polyaluminum chloride is 1:0.1, while the rest is the same as in embodiment 3.

[0042] Example 5 The difference between this embodiment and embodiment 3 is that the flocculant, by mass fraction, includes: 45 parts of polyferric sulfate and 8 parts of sodium polyacrylate, with the rest being the same as in embodiment 3.

[0043] Example 6 The difference between this embodiment and Example 3 is that the total addition amount of polyacrylamide and polyaluminum chloride is 90 g / m³. 3 The rest is the same as in Example 3.

[0044] Example 7 The difference between this embodiment and embodiment 3 is that the degreasing agent is replaced with intermediate A in step S2, and the rest is the same as in embodiment 3.

[0045] Example 8 The difference between this embodiment and embodiment 3 is that the mass ratio of ferric chloride hexahydrate and ferrous chloride tetrahydrate in step S2 is 1:0.8, while the rest is the same as in embodiment 3.

[0046] Example 9 The difference between this embodiment and Embodiment 3 is that hexadecyltrimethylammonium chloride in step S3 is replaced with ammonium chloride, while the rest is the same as in Embodiment 3.

[0047] Example 10 The difference between this embodiment and embodiment 3 is that the mass ratio of biomass precursor to hexadecyltrimethylammonium chloride in step S3 is 1:1, while the rest is the same as in embodiment 3.

[0048] Comparative Example 1 The difference between this comparative example and Example 3 is that only polyacrylamide is added in step (1), and the amount of polyacrylamide added is 55 g / m³. 3 The rest is the same as in Example 3.

[0049] Comparative Example 2 The difference between this comparative example and Example 3 is that only polyaluminum chloride is added in step (1), and the amount of polyaluminum chloride added is 55 g / m³. 3 The rest is the same as in Example 3.

[0050] Comparative Example 3 The difference between this comparative example and Example 3 is that the degreasing agent in step (2) is replaced with acrylamide and ammonium persulfate in a mass ratio of 1:2, and the rest is the same as in Example 3.

[0051] Comparative Example 4 The difference between this comparative example and Example 3 is that in step (2) of this comparative example, the degreasing agent is first mixed with water to obtain a degreasing agent solution, which is then loaded into a solution tank. After that, the degreasing agent solution and the sewage are separately transported to a mixing tank for the first stirring. Then, flocculant is added to the mixing tank for the second stirring. The rest is the same as in Example 3.

[0052] Test Example 1 The following tests were performed on the water effluent from Examples 1-10 and Comparative Examples 1-4 before and after treatment: 1) COD removal rate: The COD removal rate in wastewater was determined and calculated according to the detection method in GB / T15456-2019; 2) BOD5 removal rate: The BOD5 removal rate was determined and calculated according to the detection method in GB7488-87; 3) Suspended solids content test: The removal rate of suspended solids in water was tested according to the test method in GB11901-1989; the specific test results are shown in Table 1.

[0053] Table 1

[0054] Test Example 2 The following tests were performed on the water effluent from Examples 1-10 and Comparative Examples 1-4 before and after treatment: 1) Turbidity test: The test is conducted using a turbidimeter; 2) Total hardness test: The total hardness was determined by the disodium ethylenediaminetetraacetate titration method; the specific test results are shown in Table 2.

[0055] Table 2

[0056] Test Example 3 The following tests were performed on the water effluent after treatment in Examples 1-10 and Comparative Examples 1-4: 1) pH test: pH is measured using a pH meter; 2) Test of oil content in wastewater: Gravimetric method was used; the test results are shown in Table 3.

[0057] Table 3

[0058] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for treating wastewater generated during a cage pre-washing process, characterized in that, Includes the following steps: (1) After adding polyacrylamide and polyaluminum chloride to the wastewater generated by the cage coarse washing process, the wastewater is stirred and then subjected to the first pressure filtration to remove larger particulate impurities in the wastewater. (2) The pretreated sewage in step (1) is transported to the sewage tank. The flocculant is mixed with water to obtain flocculant solution, which is then loaded into the solution tank. The flocculant solution and sewage are then transported to the mixing tank simultaneously. The first stirring is carried out in the mixing tank. Then, the degreasing agent is added to the mixing tank for the second stirring. (3) After the water treated in step (2) is filtered for the second time, it is transported to the sedimentation tank. An oxidant is added to the sedimentation tank and the treated water is obtained after standing.

2. The wastewater treatment method for the cage rough washing process according to claim 1, characterized in that, The mass ratio of polyacrylamide to polyaluminum chloride is 1:(1-2).

3. The wastewater treatment method for the cage rough washing process according to claim 1, characterized in that, The flocculant, by mass fraction, comprises: 40-50 parts of polyferric sulfate, 5-10 parts of chitosan quaternary ammonium salt, and 5-10 parts of sodium polyacrylate.

4. The wastewater treatment method for the cage rough washing process according to claim 1, characterized in that, The total addition amount of polyacrylamide and polyaluminum chloride is 50-60 g / m³. 3 .

5. The wastewater treatment method for the cage rough washing process according to claim 1, characterized in that, The preparation method of the degreasing agent includes the following steps: S1: Biomass is treated at high temperature under an inert atmosphere to obtain biomass precursor; S2: Add biomass precursor to water, then add ferric chloride hexahydrate and ferrous chloride tetrahydrate, stir thoroughly, then add ammonia under inert gas protection to adjust the pH to 10-11, react at 70-80°C for 1-2 hours, wash until neutral, magnetically separate and dry to obtain intermediate A. S3: Add intermediate A to water, disperse evenly, add long-chain alkyl quaternary ammonium salt, mix and stir at 60-80°C for 4-8 hours, wash, magnetically separate and dry to obtain degreasing agent.

6. The wastewater treatment method for the cage rough washing process according to claim 5, characterized in that, The long-chain alkyl quaternary ammonium salt is selected from at least one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride.

7. The wastewater treatment method for the cage rough washing process according to claim 5, characterized in that, The high-temperature treatment time in step S1 is 1-1.5 hours.

8. The wastewater treatment method for the cage rough washing process according to claim 5, characterized in that, The mass ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate is 1:(1.5-2.5).

9. The wastewater treatment method for the cage rough washing process according to claim 5, characterized in that, The mass ratio of the biomass precursor, ferric chloride hexahydrate, and ferrous chloride tetrahydrate is 1:(0.2-0.3):(0.5-0.8).

10. The wastewater treatment method for the cage rough washing process according to claim 5, characterized in that, The mass ratio of the biomass precursor to the long-chain alkyl quaternary ammonium salt is 1:(8-10).

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