Cold-rolled plain carbon steel wastewater recycling treatment system and process

Abstract

The application discloses a kind of cold-rolled plain carbon steel wastewater recycling treatment system and process, it is related to sewage treatment process technical field, the system includes acidic wastewater treatment unit, emulsion wastewater treatment unit, leveling liquid wastewater treatment unit, alkaline oily wastewater treatment unit and wastewater recycling treatment unit, the acidic wastewater treatment unit, the emulsion wastewater treatment unit, the leveling liquid wastewater treatment unit all with the alkaline oily wastewater treatment unit be connected with, the alkaline oily wastewater treatment unit with the wastewater recycling treatment unit be connected with, etc.The acidic wastewater and alkaline oily wastewater after pretreatment are mutually neutralized in the application, save PH regulator dosage, reduce wastewater treatment reagent cost;At the same time, by combining the wastewater of different water quality after pretreatment and processing, simplify the process flow and the composition of processing facilities, reduce construction investment, operating cost and maintenance cost.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater reuse treatment system and process for cold-rolled carbon steel. Background Technology

[0002] The production process in the cold rolling workshop of plain carbon steel generates a large amount of acidic wastewater, alkaline oily wastewater, and acidic / alkaline / oily wastewater such as emulsions and leveling solutions. Currently, the treatment of acidic / alkaline / oily wastewater mainly involves setting up separate treatment systems for acidic wastewater, alkaline oily wastewater, emulsions, and leveling solutions, based on the type of wastewater. Among them, emulsions and leveling solutions undergo pretreatment before entering the alkaline oily wastewater treatment system for treatment to meet discharge standards or for reuse, while acidic wastewater undergoes separate treatment to meet discharge standards or for reuse.

[0003] Separate treatment of acidic and alkaline oily wastewater is convenient for control and operation management, and the technology is mature and reliable. However, the treatment of alkaline oily wastewater, emulsions, and leveling solutions consumes a large amount of acid, while the treatment of acidic wastewater consumes a large amount of alkali (lime). Separate treatment of acidic and alkaline oily wastewater requires a large amount of chemicals, which increases the salinity of the wastewater. This leads to an increase in the amount of concentrated brine produced during the deep treatment of wastewater reuse, which is not conducive to the disposal of concentrated brine by enterprises. In particular, it increases the treatment cost for enterprises to reduce the volume of concentrated brine or achieve zero discharge of wastewater throughout the plant. At the same time, the neutralization treatment of acidic wastewater consumes a large amount of lime, resulting in a high concentration of calcium chloride in the wastewater. Direct reuse of the wastewater is limited, and deep desalination treatment is required for reuse. However, deep treatment requires the addition of decalcification and hardening agents, resulting in repeated addition of agents, which increases both agent costs and operating costs. Summary of the Invention

[0004] The purpose of this invention is to provide a wastewater reuse system and process for cold-rolled carbon steel, which at least solves the problem of high wastewater treatment and reuse costs.

[0005] The above-mentioned objectives of the present invention can be achieved by the following technical solutions:

[0006] This invention provides a wastewater reuse and treatment system for cold-rolled carbon steel, comprising an acidic wastewater treatment unit, an emulsion wastewater treatment unit, a leveling liquid wastewater treatment unit, an alkaline oily wastewater treatment unit, and a wastewater reuse and treatment unit. The acidic wastewater treatment unit, the emulsion wastewater treatment unit, and the leveling liquid wastewater treatment unit are all connected to the alkaline oily wastewater treatment unit, and the alkaline oily wastewater treatment unit is connected to the wastewater reuse and treatment unit.

[0007] The acidic wastewater treatment unit is used to treat acidic wastewater, to homogenize and adjust the acidic wastewater, and to obtain primary acidic wastewater.

[0008] The emulsion wastewater treatment unit is used to treat emulsion wastewater, to separate the oil from the emulsion wastewater, and to obtain primary emulsion wastewater.

[0009] The leveling liquid wastewater treatment is used to treat leveling liquid wastewater, to separate the oil from the leveling liquid wastewater, and to obtain primary leveling liquid wastewater.

[0010] The alkaline oily wastewater treatment unit is used to mix the primary emulsion wastewater, the primary leveling liquid wastewater, and the alkaline oily wastewater to obtain primary mixed wastewater; the alkaline oily wastewater treatment unit is also used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain primary mixed wastewater; the alkaline oily wastewater treatment unit is also used to perform advanced treatment on the primary mixed wastewater to obtain secondary mixed wastewater;

[0011] The wastewater reuse treatment unit is used to receive the secondary mixed wastewater and desalinate it to obtain desalinated water and concentrated brine.

[0012] In one specific embodiment, the alkaline oily wastewater treatment unit includes an alkaline oily wastewater equalization tank, which is used to mix the primary emulsion wastewater, the primary leveling liquid wastewater and the alkaline oily wastewater to obtain the primary mixed wastewater.

[0013] In one specific embodiment, the alkaline oily wastewater treatment unit further includes at least one neutralization tank, which is connected to the acidic wastewater treatment unit. The at least one neutralization tank is used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain the primary mixed wastewater.

[0014] Preferably, the alkaline oily wastewater treatment unit includes a first neutralization tank and a second neutralization tank connected to each other. The first neutralization tank is used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain the primary mixed wastewater. The second neutralization tank is used to adjust the pH of the primary mixed wastewater to 6.5-7.5.

[0015] In one specific embodiment, the alkaline oily wastewater treatment unit further includes a mixing and flocculation treatment module, an air flotation treatment module, and a biochemical treatment module. The mixing and flocculation treatment module is used to mix and flocculate the suspended solids in the primary mixed wastewater, and to cause the suspended solids in the primary mixed wastewater to settle. The air flotation treatment module is used to further mix and flocculate the suspended solids in the primary mixed wastewater, and to reduce the total oil content in the primary mixed wastewater. The biochemical treatment module is used to reduce the organic matter in the primary mixed wastewater, and to obtain the secondary mixed wastewater.

[0016] Specifically, the mixed flocculation treatment module includes a first coagulation tank, a first flocculation tank, and a sedimentation tank connected in sequence. The first coagulation tank is used to perform preliminary coagulation of suspended solids in the primary mixed wastewater, the first flocculation tank is used to perform preliminary flocculation of suspended solids in the primary mixed wastewater, and the sedimentation tank is used to settle the suspended solids in the primary mixed wastewater.

[0017] Specifically, the flotation treatment module includes a second coagulation tank, a second flocculation tank, and a flotation tank connected in sequence. The second coagulation tank is used for secondary coagulation of suspended solids in the primary mixed wastewater, the second flocculation tank is used for secondary flocculation of suspended solids in the primary mixed wastewater, and the flotation tank is used to reduce the total oil content in the primary mixed wastewater.

[0018] Specifically, the biochemical treatment includes an anoxic tank, an aerobic tank, and an MBR membrane bioreactor. The anoxic tank is connected to the dissolved air flotation tank and is used for denitrification of the primary mixed wastewater. The aerobic tank is used to degrade COD and ammonia nitrogen in the primary mixed wastewater. The MBR membrane bioreactor is used to retain suspended solids and organic matter in the primary mixed wastewater.

[0019] In one specific embodiment, the acidic wastewater treatment unit includes an interconnected waste acid emergency conditioning tank and an acidic wastewater conditioning tank;

[0020] The waste acid emergency conditioning tank is used to homogenize and condition the hydrochloric acid or pickling waste liquid discharged in an accident. The acidic wastewater conditioning tank is used to mix and homogenize the effluent from the waste acid emergency conditioning tank and the normally discharged acidic wastewater to obtain the primary acidic wastewater.

[0021] The acidic wastewater equalization tank is connected to the first neutralization tank, or the acidic wastewater equalization tank is connected to both the first neutralization tank and the second neutralization tank.

[0022] In one specific embodiment, the emulsion wastewater treatment unit includes an emulsion wastewater equalization tank, an oil separator, a demulsification tank, an emulsion neutralization tank, an emulsion coagulation tank, an emulsion flocculation tank, and an emulsion flotation tank connected in sequence.

[0023] The emulsion wastewater equalization tank is used to homogenize and regulate the emulsion wastewater; the oil separator is used to perform preliminary oil-water separation in the emulsion wastewater; the demulsification tank is used to break up the emulsion in the emulsion wastewater; the emulsion neutralization tank is used to adjust the pH of the emulsion wastewater to 6.5-7.5; the emulsion coagulation tank is used to coagulate the suspended solids in the emulsion wastewater; the emulsion flocculation tank is used to flocculate the suspended solids in the emulsion wastewater; and the emulsion flotation tank is used to reduce the total oil content in the emulsion wastewater and obtain the primary emulsion wastewater.

[0024] The emulsion flotation tank is connected to the alkaline oily wastewater equalization tank.

[0025] In one specific embodiment, the leveling liquid wastewater treatment unit includes a leveling liquid wastewater equalization tank, an acidification tank, a leveling liquid neutralization tank, a leveling liquid coagulation tank, a leveling liquid flocculation tank, and a leveling liquid air flotation tank connected in sequence.

[0026] The leveling liquid wastewater equalization tank is used to homogenize and adjust the leveling liquid wastewater; the acidification tank is used to acidify the leveling liquid wastewater; the leveling liquid neutralization tank is used to adjust the pH of the emulsion wastewater to 6.5-7.5; the leveling liquid coagulation tank is used to coagulate the suspended solids in the leveling liquid wastewater; the leveling liquid flocculation tank is used to flocculate the suspended solids in the leveling liquid wastewater; and the leveling liquid flotation tank is used to reduce the total oil content in the leveling liquid wastewater and obtain the first-stage leveling liquid wastewater.

[0027] The leveling liquid flotation tank is connected to the alkaline oily wastewater conditioning tank.

[0028] Preferably, the acidification tank is connected to the acidic wastewater equalization tank.

[0029] In one specific embodiment, the wastewater reuse treatment unit includes an intermediate water tank, a booster pump, a security filter, and a reverse osmosis device connected in sequence;

[0030] The intermediate water tank is used to receive the secondary mixed wastewater; the booster pump is used to pressurize the secondary mixed wastewater; the security filter is used to remove residual suspended solids in the secondary mixed wastewater; and the reverse osmosis equipment is used to desalinate the secondary mixed wastewater.

[0031] In one specific embodiment, the wastewater reuse treatment system for cold-rolled carbon steel further includes a sludge dewatering unit. The sludge dewatering unit has an inlet, a first outlet, and a second outlet. The inlet is connected to the emulsion flotation tank, the leveling liquid flotation tank, the sedimentation tank, the flotation tank, and the MBR membrane bioreactor. The first outlet is connected to the alkaline oily wastewater equalization tank, and the second outlet is connected to the sludge cake storage tank.

[0032] This invention also provides a wastewater reuse treatment process for cold-rolled carbon steel, which is applicable to the aforementioned wastewater reuse treatment system for cold-rolled carbon steel and includes the following steps:

[0033] Acidic wastewater is transported to the acidic wastewater treatment unit for treatment to obtain the primary acidic wastewater; emulsion wastewater is transported to the emulsion wastewater treatment unit for treatment to obtain the primary emulsion wastewater; leveling liquid wastewater is transported to the leveling liquid wastewater treatment unit for treatment to obtain the primary leveling liquid wastewater;

[0034] The primary emulsified wastewater and the primary leveling liquid wastewater are transported to the alkaline oily wastewater equalization tank and mixed with the alkaline oily wastewater entering the alkaline oily wastewater equalization tank to obtain the primary mixed wastewater.

[0035] The primary acidic wastewater is transported to the first neutralization tank and neutralized with the primary mixed wastewater in the first neutralization tank to obtain the primary mixed wastewater;

[0036] The primary mixed wastewater is transported to the second neutralization tank, and a pH adjuster is added to adjust the pH of the primary mixed wastewater to 6.5-7.5.

[0037] The effluent from the second neutralization tank is fed into the alkaline oily wastewater treatment unit for mixing and flocculation, flotation and biochemical treatment to obtain the secondary mixed wastewater.

[0038] The secondary mixed wastewater is transported to the wastewater reuse treatment unit for desalination to obtain desalinated water and concentrated brine.

[0039] Preferably, when the pH of the primary mixed wastewater is less than 6.5, the added pH adjuster is sodium hydroxide or sodium carbonate or a combination of both; when the pH of the primary mixed wastewater is greater than 7.5, the added pH adjuster is the primary acidic wastewater or hydrochloric acid or a combination of both.

[0040] Specifically, the wastewater reuse treatment process for cold-rolled carbon steel also includes: aerating the waste acid emergency conditioning tank, the acidic wastewater conditioning tank, the first neutralization tank, and the second neutralization tank to oxidize ferrous ions in the wastewater to ferric ions.

[0041] Specifically, the wastewater reuse treatment process for cold-rolled carbon steel also includes: aerating the alkaline oily wastewater regulating tank to prevent the sedimentation of suspended solids in the primary mixed wastewater.

[0042] Specifically, the wastewater reuse treatment process for cold-rolled carbon steel also includes: using contact oxidation technology to aerate both the aerobic tank and the MBR membrane bioreactor to degrade COD and ammonia nitrogen in the primary mixed wastewater.

[0043] The features and advantages of this invention are as follows: The wastewater reuse treatment system and process for cold-rolled carbon steel provided by this invention utilizes the pretreated acidic wastewater and alkaline oily wastewater to neutralize each other, saving the amount of pH adjuster added and reducing the cost of wastewater treatment agents; at the same time, the pretreated emulsion wastewater, leveling liquid wastewater and alkaline oily wastewater are treated together, simplifying the treatment process and the composition of the treatment facilities; in addition, during the pH adjustment process, the alkaline pH adjuster added is sodium hydroxide or sodium carbonate, and the acidic pH adjuster added is hydrochloric acid or pretreated acidic wastewater, which reduces the hardness of the wastewater treated effluent, facilitates wastewater reuse, reduces the volume of concentrated brine, and improves the purity of the concentrated brine evaporation crystallization salt, thus reducing the amount of impurities produced. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the composition of the wastewater reuse treatment system for cold-rolled carbon steel provided in this embodiment of the invention;

[0046] Figure 2 This is a process flow diagram of the wastewater reuse treatment process for cold-rolled carbon steel provided in this embodiment of the invention.

[0047] Explanation of icon numbers:

[0048] 1. Acidic wastewater treatment unit; 11. Waste acid emergency equalization tank; 12. Acidic wastewater equalization tank;

[0049] 2. Emulsion wastewater treatment unit; 21. Emulsion wastewater equalization tank; 22. Oil separator; 23. Demulsification tank; 24. Emulsion neutralization tank; 25. Emulsion coagulation tank; 26. Emulsion flocculation tank; 27. Emulsion flotation tank;

[0050] 3. Leveling liquid wastewater treatment unit; 31. Leveling liquid wastewater equalization tank; 32. Acidification tank; 33. Leveling liquid neutralization tank; 34. Leveling liquid coagulation tank; 35. Leveling liquid flocculation tank; 36. Leveling liquid flotation tank;

[0051] 4. Alkaline oily wastewater treatment unit; 41. Alkaline oily wastewater equalization tank; 42. First neutralization tank; 43. Second neutralization tank; 44. Mixed flocculation treatment module; 441. First coagulation tank; 442. First flocculation tank; 443. Sedimentation tank; 45. Air flotation treatment module; 451. Second coagulation tank; 452. Second flocculation tank; 453. Air flotation tank; 46. Biochemical treatment module; 461. Anoxic tank; 462. Aerobic tank; 463. MBR membrane bioreactor;

[0052] 5. Wastewater reuse and treatment unit;

[0053] 6. Sludge dewatering treatment unit. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] like Figure 1 As shown, the present invention provides a wastewater reuse treatment system for cold-rolled carbon steel, including an acidic wastewater treatment unit 1, an emulsion wastewater treatment unit 2, a leveling liquid wastewater treatment unit 3, an alkaline oily wastewater treatment unit 4, a wastewater reuse treatment unit 5, and a sludge dewatering treatment unit 6. The acidic wastewater treatment unit 1, the emulsion wastewater treatment unit 2, and the leveling liquid wastewater treatment unit 3 are all connected to the alkaline oily wastewater treatment unit 4. The alkaline oily wastewater treatment unit 4 is connected to the wastewater reuse treatment unit 5. The sludge dewatering treatment unit 6 is connected to the emulsion wastewater treatment unit 2, the leveling liquid wastewater treatment unit 3, and the alkaline oily wastewater treatment unit 4.

[0056] The system includes: an acidic wastewater treatment unit 1 for treating acidic wastewater, homogenizing and adjusting it to obtain primary acidic wastewater; an emulsion wastewater treatment unit 2 for treating emulsion wastewater, separating the oil from the emulsion wastewater to obtain primary emulsion wastewater; a leveling liquid wastewater treatment unit 4 for treating leveling liquid wastewater, separating the oil from the leveling liquid wastewater to obtain primary leveling liquid wastewater; an alkaline oily wastewater treatment unit 4 for mixing primary emulsion wastewater, primary leveling liquid wastewater, and alkaline oily wastewater to obtain primary mixed wastewater; an alkaline oily wastewater treatment unit 4 for neutralizing primary acidic wastewater and primary mixed wastewater to obtain primary mixed wastewater; an alkaline oily wastewater treatment unit 4 for further treating primary mixed wastewater to obtain secondary mixed wastewater; and a wastewater reuse treatment unit 5 for receiving secondary mixed wastewater and desalinating it to obtain desalinated water and concentrated brine. In this embodiment, the advanced treatment of the primary mixed wastewater by the alkaline oily wastewater treatment unit 4 includes: adjusting the pH of the primary mixed wastewater to 6.5-7.5, and reducing suspended solids, oil, COD (Chemical Oxygen Demand), metal ions, etc. in the primary mixed wastewater. COD, or Chemical Oxygen Demand, refers to the amount of oxidant consumed when treating a water sample with a certain strong oxidant under specific conditions; it is generally used to represent the total amount of organic matter in wastewater.

[0057] In the acidic wastewater treatment unit 1, continuous aeration and stirring are required during the treatment of acidic wastewater to ensure the homogeneity of the wastewater volume and quality. Simultaneously, aeration and stirring also oxidize ferrous ions in the acidic wastewater to ferric ions, preventing the ferrous ions from reacting with the alkaline pH adjuster and forming precipitation, which would otherwise affect the wastewater treatment efficiency, when the pH needs to be adjusted later. Preferably, the aeration rate of acidic wastewater treatment unit 1 is controlled within the range of 0.35 m³ / h. 3 / m 3 .h~0.6m 3 / m 3 .h

[0058] Specifically, such as Figure 1As shown, the wastewater reuse and treatment system for cold-rolled carbon steel includes an acidic wastewater treatment unit 1, an emulsion wastewater treatment unit 2, a leveling liquid wastewater treatment unit 3, an alkaline oily wastewater treatment unit 4, a wastewater reuse treatment unit 5, and a sludge dewatering treatment unit 6. By setting up treatment units corresponding to the wastewater types, the wastewater is pretreated in categories to obtain primary wastewater corresponding to each wastewater type. Simultaneously, by connecting the acidic wastewater treatment unit 1, the emulsion wastewater treatment unit 2, the leveling liquid wastewater treatment unit 3, and the alkaline oily wastewater treatment unit 4, the various types of wastewater after pretreatment can be treated together, reducing both the construction investment of the wastewater treatment system and the cost of wastewater treatment. The process involves neutralizing the pretreated primary acidic wastewater with the alkaline oily wastewater, which saves on pH adjuster dosage and reduces wastewater treatment reagent costs. Furthermore, no lime is added during the wastewater treatment process, resulting in no calcium chloride production in the treated effluent and low hardness, thus expanding the scope of wastewater reuse. The subsequent wastewater reuse treatment unit 5 does not require decalcification or hardening treatment of the combined secondary mixed wastewater, saving on investment in decalcification and hardening softening facilities. By combining the pretreated primary emulsion wastewater, primary leveling liquid wastewater, and alkaline oily wastewater for treatment, the subsequent treatment processes of the primary emulsion wastewater and primary leveling liquid wastewater are carried out simultaneously with the alkaline oily wastewater treatment, simplifying the treatment facility composition, reducing land area, and lowering overall construction investment, operating costs, and maintenance expenses.

[0059] According to one embodiment of the present invention, such as Figure 1 As shown, the acidic wastewater treatment unit 1 includes a waste acid emergency conditioning tank 11 and an acidic wastewater conditioning tank 12 connected to each other. The waste acid emergency conditioning tank 11 is used to homogenize and condition the hydrochloric acid or pickling waste liquid discharged in an emergency. The acidic wastewater conditioning tank 12 is used to mix and homogenize the effluent from the waste acid emergency conditioning tank 11 and the normally discharged acidic wastewater to obtain primary acidic wastewater.

[0060] Specifically, the acidic wastewater normally discharged from the cold rolling workshop is sent to the acidic wastewater equalization tank 12 for continuous aeration and stirring to achieve homogenization of water quantity and quality. Hydrochloric acid or pickling wastewater discharged during workshop accidents first enters the waste acid accident equalization tank 11 for continuous aeration and stirring for homogenization. Then, the waste acid in the waste acid accident equalization tank 11 is continuously discharged into the acidic wastewater equalization tank 12, allowing the high-concentration accident waste acid to mix and dilute with the acidic wastewater in the acidic wastewater equalization tank 12, ensuring stable effluent quality from the acidic wastewater equalization tank 12. The primary acidic wastewater output from the acidic wastewater equalization tank 12 is sent to the alkaline oily wastewater treatment unit 4 for use as a neutralizing agent. Preferably, the chloride ion content in the effluent from the acidic wastewater equalization tank 12 is less than 10000 mg / L, and the accident waste acid in the waste acid accident equalization tank 11 is treated within 5-10 days. Among them, the acidic wastewater equalization tank 12 and the waste acid emergency equalization tank 11 are equipped with aeration and stirring, which, in addition to regulating the flow and quality of water, also oxidizes divalent ferric ions in the wastewater to trivalent ferric ions. The aeration and stirring device can be perforated pipe aeration, aeration disc aeration, etc., which are preferred. The aeration rate is controlled within a range of 0.35 m³ / h. 3 / m 3 .h~0.6m 3 / m 3 In this embodiment, the waste acid emergency equalization tank 11 has one compartment, and the acidic wastewater equalization tank 12 has two compartments connected in series.

[0061] According to one embodiment of the present invention, such as Figure 1 As shown, the emulsion wastewater treatment unit 2 includes an emulsion wastewater equalization tank 21, an oil separator 22, a demulsification tank 23, an emulsion neutralization tank 24, an emulsion coagulation tank 25, an emulsion flocculation tank 26, and an emulsion flotation tank 27, which are connected in sequence. The emulsion wastewater equalization tank 21 is used to homogenize and adjust the emulsion wastewater; the oil separator 22 is used to perform preliminary oil-water separation in the emulsion wastewater; the demulsification tank 23 is used to break up the emulsion in the emulsion wastewater; the emulsion neutralization tank 24 is used to adjust the pH of the emulsion wastewater to 6.5-7.5; the emulsion coagulation tank 25 is used to coagulate the suspended solids in the emulsion wastewater; the emulsion flocculation tank 26 is used to flocculate the suspended solids in the emulsion wastewater; and the emulsion flotation tank 27 is used to reduce the total oil content in the emulsion wastewater and obtain primary emulsion wastewater. The emulsion flotation tank 27 is connected to the alkaline oily wastewater treatment unit 4.

[0062] Specifically, the emulsion wastewater discharged from the cold rolling workshop first enters the emulsion wastewater equalization tank 21 for water quantity and quality homogenization adjustment, and then is sequentially transported to the oil separator 22, demulsification tank 23, emulsion neutralization tank 24, emulsion coagulation tank 25, emulsion flocculation tank 26 and emulsion flotation tank 27 for further treatment to achieve demulsification and oil-water separation. In this process, the emulsion wastewater equalization tank 21 and the oil separator 22 achieve preliminary oil-water separation through steam heating, and the floating oil is collected and transported for unified treatment using an oil skimmer. Specifically, the emulsion wastewater equalization tank 21 can add primary acidic wastewater to prevent saponification. Preferably, the emulsion wastewater equalization tank 21 is divided into two compartments and operated in series. The demulsification tank 23 adopts chemical demulsification and adds demulsifier to achieve oil-water separation of the emulsion. The pH value is adjusted by adding alkali or acid in the emulsion neutralization tank 24. Preferably, acidic wastewater is added for acid adjustment and sodium hydroxide is added for alkali adjustment. The effluent from the emulsion neutralization tank 24 passes through the emulsion coagulation tank 25 and the emulsion flocculation tank 26 to remove suspended solids in the emulsion wastewater, and then passes through the emulsion flotation tank 27 to further achieve oil-water separation. The scum collected from the emulsion flotation tank 27 is discharged into the sludge dewatering treatment unit 6 for unified treatment. The primary emulsion wastewater output from the emulsion flotation tank 27 is sent to the alkaline oily wastewater treatment unit 4 for combined treatment. Preferably, the COD content in the effluent from the emulsion flotation tank 27 is less than 1000 mg / L.

[0063] According to one embodiment of the present invention, such as Figure 1 As shown, the leveling liquid wastewater treatment unit 3 includes a leveling liquid wastewater equalization tank 31, an acidification tank 32, a leveling liquid neutralization tank 33, a leveling liquid coagulation tank 34, a leveling liquid flocculation tank 35, and a leveling liquid flotation tank 36 connected in sequence. The leveling liquid wastewater equalization tank 31 is used to homogenize and adjust the leveling liquid wastewater; the acidification tank 32 is used to acidify the leveling liquid wastewater to improve the oil-water separation efficiency; the leveling liquid neutralization tank 33 is used to adjust the pH of the emulsion wastewater to 6.5–7.5; the leveling liquid coagulation tank 34 is used to coagulate suspended solids in the leveling liquid wastewater; the leveling liquid flocculation tank 35 is used to flocculate suspended solids in the leveling liquid wastewater; and the leveling liquid flotation tank 36 is used to reduce the total oil content in the leveling liquid wastewater and obtain primary leveling liquid wastewater. The leveling liquid flotation tank 36 is connected to the alkaline oily wastewater treatment unit 4.

[0064] Specifically, the leveling solution wastewater discharged from the cold rolling workshop first enters the leveling solution wastewater equalization tank 31 for water quantity and quality homogenization adjustment. Then, it passes through the acidification tank 32, leveling solution neutralization tank 33, leveling solution coagulation tank 34, leveling solution flocculation tank 35, and leveling solution flotation tank 36 for further treatment to achieve oil-water separation. In this process, primary acidic wastewater is added to the acidification tank 32 for acidification treatment to achieve oil-water separation of the leveling solution wastewater. Preferredly, the acidification tank 32 is connected to the acidic wastewater equalization tank 12. Sodium hydroxide is added to the leveling solution neutralization tank 33 to adjust the pH value. The effluent from the leveling solution neutralization tank 33 passes through the leveling solution coagulation tank 34 and the leveling solution flocculation tank 35 to remove suspended solids in the leveling solution wastewater, and then passes through the leveling solution flotation tank 36 for further oil-water separation. The scum collected from the leveling liquid flotation tank 36 is discharged into the sludge dewatering treatment unit 6 for unified treatment. The primary leveling liquid wastewater output from the leveling liquid flotation tank 36 is sent to the alkaline oily wastewater treatment unit 4 for combined treatment. Preferably, the COD content in the effluent from the leveling liquid flotation tank 36 is less than 1000 mg / L.

[0065] According to one embodiment of the present invention, such as Figure 1 As shown, the alkaline oily wastewater treatment unit 4 includes an alkaline oily wastewater equalization tank 41. The alkaline oily wastewater equalization tank 41 is used to mix the primary emulsion wastewater, the primary leveling liquid wastewater, and the alkaline oily wastewater to obtain primary mixed wastewater. Specifically, as shown... Figure 1 As shown, both the emulsion flotation tank 27 and the leveling liquid flotation tank 36 are connected to the alkaline oily wastewater equalization tank 41. The primary emulsion wastewater obtained after pretreatment by the emulsion wastewater treatment unit 2 and the primary leveling liquid wastewater obtained after pretreatment by the leveling liquid wastewater treatment unit 3 are transported to the alkaline oily wastewater equalization tank 41 for combined treatment with the alkaline oily wastewater discharged from the cold rolling workshop, saving investment in treatment facility construction and land area. The primary emulsion wastewater and primary leveling liquid wastewater are mixed with the cold rolling alkaline oily wastewater in the alkaline oily wastewater equalization tank 41 to form primary mixed wastewater. During the process of homogenizing the quantity and quality of the primary mixed wastewater, continuous aeration and stirring are required in the alkaline oily wastewater equalization tank 41 to prevent the sedimentation of suspended solids in the primary mixed wastewater, which would affect the homogenization effect. Preferably, the alkaline oily wastewater equalization tank 41 is divided into two compartments connected in series.

[0066] According to one embodiment of the present invention, such as Figure 1As shown, the alkaline oily wastewater treatment unit 4 also includes at least one neutralization tank, which is connected to the acidic wastewater treatment unit 1. The at least one neutralization tank is used to neutralize the primary acidic wastewater and the initial mixed wastewater to obtain primary mixed wastewater. Specifically, by conveying the primary acidic wastewater to the at least one neutralization tank of the alkaline oily wastewater treatment unit 4, acid-base neutralization is achieved, and primary mixed wastewater is obtained, thereby reducing the amount of pH adjuster required in subsequent treatment processes or eliminating the need for pH adjuster addition altogether.

[0067] Preferably, such as Figure 1 As shown, the alkaline oily wastewater treatment unit 4 includes a first neutralization tank 42 and a second neutralization tank 43 connected to each other. The first neutralization tank 42 is used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain primary mixed wastewater. The second neutralization tank 43 is used to adjust the pH of the primary mixed wastewater to 6.5 to 7.5.

[0068] Specifically, the acidic wastewater equalization tank 12 is connected to the first neutralization tank 42. The primary acidic wastewater output from the acidic wastewater equalization tank 12 is directly transported to the first neutralization tank 42 to neutralize with the primary mixed wastewater, forming a primary mixed wastewater. The second neutralization tank 43 is equipped with an electrically connected pH meter and an automatic pH adjuster dosing device. The pH meter is used to detect the acidity or alkalinity of the primary mixed wastewater output from the first neutralization tank 42 and feeds back the detected acidity or alkalinity signal to the automatic pH adjuster dosing device. The automatic pH adjuster dosing device automatically adds an appropriate amount of pH adjuster according to the received acidity or alkalinity signal to adjust the acidity or alkalinity of the primary mixed wastewater to 6.5-7.5. Both the first neutralization tank 42 and the second neutralization tank 43 require continuous aeration and mechanical stirring to oxidize the residual ferrous ions in the primary acidic wastewater to ferric ions. This prevents the ferrous ions from reacting with the alkaline pH adjuster during subsequent pH adjustment of the primary mixed wastewater, which could lead to precipitation and affect neutralization efficiency. Mechanical stirring also improves the efficiency of the neutralization reaction. Preferably, the aeration rate in the first neutralization tank 42 and the second neutralization tank 43 is controlled within the range of 0.45 m³ / h. 3 / m 3 .h~0.6m 3 / m 3 The aeration time is controlled within the range of 35 min to 60 min.

[0069] In this embodiment, the automatic pH adjuster dosing device can automatically select to add either an acidic or alkaline pH adjuster based on the acidity / alkalinity signal fed back by the pH value detection instrument. When the pH of the primary mixed wastewater is less than 6.5, an alkaline pH adjuster is added; when the pH of the primary mixed wastewater is greater than 7.5, an acidic pH adjuster is added. The alkaline pH adjuster is sodium hydroxide or sodium carbonate, or a combination of both, while the acidic pH adjuster is the primary acidic wastewater, hydrochloric acid, or a combination of both. That is, when the primary acidic wastewater is added as the pH adjuster in the second neutralization tank 43, the acidic wastewater adjustment tank 12 is connected to both the first neutralization tank 42 and the second neutralization tank 43. Thus, the main salt content of the treated wastewater is sodium chloride, which helps to improve the purity of the concentrated brine evaporation crystals and reduce the amount of impurities produced.

[0070] According to one embodiment of the present invention, such as Figure 1 As shown, the alkaline oily wastewater treatment unit 4 also includes a mixing and flocculation treatment module 44, an air flotation treatment module 45, and a biochemical treatment module 46. The mixing and flocculation treatment module 44 is used to mix and flocculate the suspended solids in the primary mixed wastewater and cause the suspended solids in the primary mixed wastewater to settle. The air flotation treatment module 45 is used to mix and flocculate the suspended solids in the primary mixed wastewater for a secondary time and reduce the total oil content in the primary mixed wastewater. The biochemical treatment module 46 is used to reduce the organic matter in the primary mixed wastewater and obtain secondary mixed wastewater.

[0071] In one preferred embodiment of the present invention, such as Figure 1 As shown, the mixed flocculation treatment module 44 includes a first coagulation tank 441, a first flocculation tank 442, and a sedimentation tank 443 connected in sequence. The first coagulation tank 441 is used to perform preliminary coagulation of suspended solids in the primary mixed wastewater, the first flocculation tank 442 is used to perform preliminary flocculation of suspended solids in the primary mixed wastewater, and the sedimentation tank 443 is used to settle suspended solids in the primary mixed wastewater.

[0072] Specifically, the effluent from the second neutralization tank 43 is sequentially transported to the first coagulation tank 441 and the first flocculation tank 442 for further treatment. During this process, coagulant is added to the first coagulation tank 441 to perform preliminary coagulation of suspended solids in the primary mixed wastewater, and flocculant is added to the first flocculation tank 442 to perform preliminary flocculation and agglomeration of suspended solids in the primary mixed wastewater. The first coagulation tank 441 and the first flocculation tank 442 are continuously mechanically stirred to prevent suspended solids from settling and affecting the subsequent wastewater treatment effect. The effluent from the first flocculation tank 442 is transported to the sedimentation tank 443, where solids quickly settle and form sludge at the bottom of the sedimentation tank 443. Part of the sludge discharged from the bottom of the sedimentation tank 443 is returned to the coagulation tank, and the other part is periodically discharged to the sludge dewatering treatment unit 6 for unified treatment. The scum on the surface of the sedimentation tank 443 is collected and discharged into the sludge dewatering treatment unit 6 for unified treatment. The clarified effluent from the sedimentation tank 443 is transported to the air flotation treatment module 45 for further treatment. To facilitate the collection of scum and thorough sludge removal, a scum scraper is installed at the top of the sedimentation tank 443, and an automatic sludge discharge machine is installed at the bottom. In this embodiment, to ensure clarification, the sedimentation tank 443 is a radial sedimentation tank. Preferably, the surface load control range of the radial sedimentation tank 443 is 0.5m. 3 / m 2 .h~0.8m 3 / m 2 .h

[0073] In one preferred embodiment of the present invention, such as Figure 1 As shown, the flotation treatment module 45 includes a second coagulation tank 451, a second flocculation tank 452, and a flotation tank 453 connected in sequence. The second coagulation tank 451 is used to perform secondary coagulation on the suspended solids in the primary mixed wastewater, the second flocculation tank 452 is used to perform secondary flocculation on the suspended solids in the primary mixed wastewater, and the flotation tank 453 is used to reduce the total oil content in the primary mixed wastewater.

[0074] Specifically, the clarified effluent from sedimentation tank 443 is sequentially transported to the second coagulation tank 451 and the second flocculation tank 452 for further treatment. During this process, the treatment process in the second coagulation tank 451 is the same as that in the first coagulation tank 441, and the treatment process in the second flocculation tank 452 is the same as that in the first flocculation tank 442. The clarified effluent from sedimentation tank 443 undergoes secondary coagulation in the second coagulation tank 451, and secondary flocculation and agglomeration in the second flocculation tank 452, to further remove suspended solids from the primary mixed wastewater. The effluent from the second flocculation tank 452 is transported to the dissolved air flotation tank 453 for dissolved air flotation treatment to reduce the total oil content in the primary mixed wastewater. The scum collected from the dissolved air flotation tank 453 is discharged into the sludge dewatering unit 6 for unified treatment; the effluent from the dissolved air flotation tank 453 is then transported to the biological treatment module 46 for further treatment. Similarly, to facilitate scum collection and thorough sludge removal, the dissolved air flotation tank 453 is equipped with a scum scraper at the top and an automatic sludge discharge machine at the bottom. The effluent temperature of the dissolved air flotation (DAF) tank 453 should be controlled at 35 degrees Celsius or below to prevent excessively high temperatures from affecting the biochemical treatment effect. Optionally, a cooling tower can be installed between the DAF treatment module 45 and the biochemical treatment module 46 to cool the effluent from the DAF tank 453 to a temperature not exceeding 35 degrees Celsius before it is sent to the biochemical treatment module 46. In this embodiment, the COD content in the effluent from the DAF tank 453 is 300 mg / L to 1000 mg / L, the suspended solids content is less than 50 mg / L, and the pH value is 6.5 to 7.5. Preferably, the DAF tank 453 adopts a single-stage dissolved air flotation, or a two-stage dissolved air flotation, or a single-stage vortex flotation plus a single-stage dissolved air flotation.

[0075] In one preferred embodiment of the present invention, such as Figure 1 As shown, the biochemical treatment includes an anoxic tank 461, an aerobic tank 462, and an MBR membrane bioreactor 463. The anoxic tank 461 is connected to the dissolved air flotation tank 453. The anoxic tank 461 is used for denitrification of the primary mixed wastewater. The aerobic tank 462 is used to degrade COD and ammonia nitrogen in the primary mixed wastewater. The MBR membrane bioreactor 463 is used to intercept suspended solids and organic matter in the primary mixed wastewater.

[0076] Specifically, the effluent from the flotation tank 453 is sequentially transported to the anoxic tank 461, the aerobic tank 462, and the MBR membrane bioreactor 463 for biochemical treatment, achieving the degradation of organic matter, COD, and ammonia nitrogen in the primary mixed wastewater. During the biochemical treatment process, glucose, starch, and ethanol are added to supplement carbon sources; urea is added to supplement nitrogen sources; and sodium dihydrogen phosphate is added to supplement phosphorus sources. The anoxic tank 461 primarily performs denitrification; the aerobic tank 462 uses contact oxidation technology, mainly to degrade COD and ammonia nitrogen in the wastewater; and the MBR membrane bioreactor 463 uses a submerged ultrafiltration device to retain suspended solids and some organic matter, ensuring that the biochemically treated effluent can be directly transported to the reverse osmosis equipment in the wastewater reuse treatment unit 5.

[0077] The aerobic tank 462 and the anoxic tank 461 are equipped with a continuous digestate return facility. The return ratio is controlled according to the total nitrogen control index of the effluent from the biological treatment tank. Preferably, the return ratio is controlled within the range of 100% to 300%. The MBR membrane bioreactor 463 and the aerobic tank 462 are connected by continuous or intermittent sludge return. Preferably, the sludge return ratio is controlled within the range of 50% to 100%, or the sludge return ratio is determined according to the requirements of the MBR membrane bioreactor manufacturer. Both the digestate return and the sludge return enter the anoxic tank 461. The effluent from the MBR membrane bioreactor 463 is directly transported to the wastewater reuse treatment unit 5 for further treatment.

[0078] In this embodiment, the anoxic tank 461 adopts a two-compartment design, with the first and second compartments operating in series. Digestering liquid return and sludge return are both fed to the first compartment of the anoxic tank 461. The dissolved oxygen concentration in the first compartment of the anoxic tank 461 is no greater than 0.5 mg / L to ensure denitrification efficiency. Furthermore, the anoxic tank 461 is equipped with suspended packing material and a submersible agitator, and an automatic sludge removal machine is located at the bottom. The aerobic tank 462 adopts a design with at least two compartments operating in series. It is equipped with suspended packing material and an aeration device to ensure contact oxidation efficiency. The COD content in the effluent from the aerobic tank 462 is less than 50 mg / L. The MBR membrane bioreactor 463 can use a submerged membrane, an offline external pressure membrane, or a ceramic membrane. The submerged membrane can be a flat sheet membrane or a hollow fiber membrane. Preferably, the COD content in the effluent from the MBR membrane bioreactor is less than 30 mg / L.

[0079] According to one embodiment of the present invention, the wastewater reuse treatment unit 5 includes an intermediate water tank, a booster pump, a security filter, and a reverse osmosis unit connected in sequence. The intermediate water tank is used to receive secondary mixed wastewater; the booster pump is used to pressurize the secondary mixed wastewater; the security filter is used to remove residual suspended solids in the secondary mixed wastewater; and the reverse osmosis unit is used to desalinate the secondary mixed wastewater. The reverse osmosis unit performs membrane desalination of the secondary mixed wastewater, and the security filter protects the reverse osmosis membrane from being scratched or clogged by residual suspended solids in the secondary mixed wastewater, thus affecting the desalination effect. The concentrated brine output from the reverse osmosis unit is supplied to low-quality water users or transported to the enterprise's concentrated brine concentration and reduction, evaporation crystallization, and salt separation facilities for evaporation crystallization treatment. The desalinated water output from the reverse osmosis unit is supplied as primary desalinated water or reused as fresh water for production. The chloride ion content in the effluent from the reverse osmosis unit is less than 250 mg / L.

[0080] According to one embodiment of the present invention, such as Figure 1As shown, the sludge dewatering unit 6 has an inlet, a first outlet, and a second outlet. The inlet is connected to the emulsion flotation tank 27, the leveling liquid flotation tank 36, the sedimentation tank 443, the flotation tank 453, and the MBR membrane bioreactor 463. The first outlet is connected to the alkaline oily wastewater equalization tank 41, and the second outlet is connected to the sludge cake storage tank. Specifically, the sludge dewatering unit 6 includes a sludge thickening tank and a plate and frame filter press. The inlet of the sludge thickening tank is also the inlet of the sludge dewatering unit 6, the sludge cake outlet of the plate and frame filter press is the second outlet of the sludge dewatering unit 6, and the filtrate outlet of the plate and frame filter press is the first outlet of the sludge dewatering unit 6. The sludge and scum generated from the emulsion flotation tank 27, the leveling liquid flotation tank 36, the sedimentation tank 443, the flotation tank 453, and the MBR membrane bioreactor 463 are all transported to the sludge thickening tank. After sludge thickening, it is transported to the plate and frame filter press for sludge dewatering. The sludge cake produced by the plate and frame filter press is stored in the sludge cake storage tank from the sludge cake outlet, and then transported to the sintering workshop for reuse. The filtrate produced by the plate and frame filter press is returned to the alkaline oily wastewater equalization tank 41.

[0081] like Figure 1 and Figure 2 As shown, the present invention also provides a wastewater reuse treatment process for cold-rolled carbon steel, which is applicable to the above-mentioned wastewater reuse treatment system for cold-rolled carbon steel, and includes the following steps:

[0082] Step S1: The acidic wastewater is transported to acidic wastewater treatment unit 1 for treatment to obtain primary acidic wastewater; the emulsion wastewater is transported to emulsion wastewater treatment unit 2 for treatment to obtain primary emulsion wastewater; the leveling liquid wastewater is transported to leveling liquid wastewater treatment unit 3 for treatment to obtain primary leveling liquid wastewater.

[0083] Step S2: The primary emulsion wastewater and the primary leveling liquid wastewater are transported to the alkaline oily wastewater equalization tank 41 and mixed with the alkaline oily wastewater entering the alkaline oily wastewater equalization tank 41 to obtain primary mixed wastewater.

[0084] Step S3: The primary acidic wastewater is transported to the first neutralization tank 42 and neutralized with the primary mixed wastewater in the first neutralization tank 42 to obtain primary mixed wastewater.

[0085] Step S4: The primary mixed wastewater is transported to the second neutralization tank 43, and a pH adjuster is added to adjust the pH of the primary mixed wastewater to 6.5-7.5.

[0086] Step S5: The effluent from the second neutralization tank 43 is fed into the alkaline oily wastewater treatment unit 4 for mixed flocculation treatment, air flotation treatment and biochemical treatment to obtain secondary mixed wastewater.

[0087] Step S6: The secondary mixed wastewater is transported to the wastewater reuse treatment unit 5 for desalination treatment to obtain desalinated water and concentrated brine.

[0088] In step S1, the accidental waste acid enters the waste acid accident equalization tank 11 for homogenization and adjustment, and then is transported to the acidic wastewater equalization tank 12 to be mixed and diluted with the normally discharged acidic wastewater from the workshop. After homogenization, it becomes primary acidic wastewater. The emulsion wastewater undergoes demulsification, neutralization, coagulation, flocculation, and flotation treatments in sequence to become primary emulsion wastewater. The leveling liquid wastewater undergoes acidification, neutralization, coagulation, flocculation, and flotation treatments in sequence to become primary leveling liquid wastewater.

[0089] In step S4, preferably, when the pH of the primary mixed wastewater is less than 6.5, the added pH adjuster is sodium hydroxide or sodium carbonate or a combination of both; when the pH of the primary mixed wastewater is greater than 7.5, the added pH adjuster is primary acidic wastewater or hydrochloric acid or a combination of both.

[0090] In step S5, the mixed flocculation treatment includes coagulation treatment, flocculation treatment, and sedimentation treatment; the air flotation treatment includes secondary coagulation treatment, secondary flocculation treatment, and air flotation treatment; and the biological treatment includes anoxic treatment, aerobic treatment, and MBR treatment. The effluent temperature from the air flotation treatment should be controlled at 35 degrees Celsius or below to prevent excessively high temperatures from affecting the biological treatment effect. Optionally, a cooling treatment can be set between the air flotation treatment and the biological treatment to cool the effluent from the air flotation treatment to a temperature not exceeding 35 degrees Celsius before subjecting it to biological treatment.

[0091] Specifically, the wastewater reuse treatment process for cold-rolled carbon steel also includes: aeration treatment of the waste acid emergency conditioning tank 11, acidic wastewater conditioning tank 12, first neutralization tank 42 and second neutralization tank 43, which is used to oxidize the divalent iron ions in the wastewater to trivalent iron ions.

[0092] Specifically, the wastewater reuse treatment process for cold-rolled carbon steel also includes: aeration treatment of alkaline oily wastewater regulating tank 41 to prevent the sedimentation of suspended solids in the primary mixed wastewater.

[0093] Specifically, the wastewater reuse treatment process for cold-rolled carbon steel also includes: using contact oxidation technology for aeration treatment of both aerobic tank 462 and MBR membrane bioreactor 463 to degrade COD and ammonia nitrogen in primary mixed wastewater.

[0094] The wastewater reuse and treatment system and process for cold-rolled carbon steel provided by this invention utilizes the pre-treated acidic wastewater and alkaline oily wastewater to neutralize each other, saving the amount of pH adjuster added and reducing the cost of wastewater treatment agents. At the same time, the pre-treated emulsion wastewater, leveling liquid wastewater and alkaline oily wastewater are treated together, simplifying the treatment process and the composition of the treatment facilities. In addition, during the pH adjustment process, the alkaline pH adjuster added is sodium hydroxide or sodium carbonate, and the acidic pH adjuster added is hydrochloric acid or pre-treated acidic wastewater, which reduces the hardness of the wastewater effluent, facilitates wastewater reuse, reduces the volume of concentrated brine, and improves the purity of the concentrated brine evaporation crystallization salt, thus reducing the amount of impurities generated.

[0095] The above descriptions are merely a few embodiments of the present invention. Those skilled in the art can make various modifications or variations to the embodiments of the present invention based on the content disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A wastewater reuse and treatment system for cold-rolled carbon steel, characterized in that, It includes an acidic wastewater treatment unit, an emulsion wastewater treatment unit, a leveling liquid wastewater treatment unit, an alkaline oily wastewater treatment unit, and a wastewater reuse treatment unit. The acidic wastewater treatment unit, the emulsion wastewater treatment unit, and the leveling liquid wastewater treatment unit are all connected to the alkaline oily wastewater treatment unit, and the alkaline oily wastewater treatment unit is connected to the wastewater reuse treatment unit. The acidic wastewater treatment unit is used to treat acidic wastewater, to homogenize and adjust the acidic wastewater, and to obtain primary acidic wastewater. The emulsion wastewater treatment unit is used to treat emulsion wastewater, to separate the oil from the emulsion wastewater, and to obtain primary emulsion wastewater. The leveling liquid wastewater treatment unit is used to treat the leveling liquid wastewater, and to separate the oil from the leveling liquid wastewater to obtain primary leveling liquid wastewater. The alkaline oily wastewater treatment unit includes an alkaline oily wastewater equalization tank, which is used to mix the primary emulsion wastewater, the primary leveling liquid wastewater, and the alkaline oily wastewater to obtain primary mixed wastewater; the alkaline oily wastewater treatment unit is also used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain primary mixed wastewater; the alkaline oily wastewater treatment unit includes a first neutralization tank and a second neutralization tank connected to each other, the first neutralization tank being used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain the primary mixed wastewater; the second neutralization tank being used to adjust the pH of the primary mixed wastewater to 6.5~7.5; The alkaline oily wastewater treatment unit is also used to further treat the primary mixed wastewater to obtain secondary mixed wastewater; The wastewater reuse treatment unit is used to receive the secondary mixed wastewater and desalinate it to obtain desalinated water and concentrated brine. The acidic wastewater treatment unit includes an interconnected waste acid emergency equalization tank and an acidic wastewater equalization tank. The waste acid emergency conditioning tank is used to homogenize and condition the hydrochloric acid or pickling waste liquid discharged in an accident. The acidic wastewater conditioning tank is used to mix and homogenize the effluent from the waste acid emergency conditioning tank and the normally discharged acidic wastewater to obtain the primary acidic wastewater. The acidic wastewater equalization tank is connected to the first neutralization tank, or the acidic wastewater equalization tank is connected to both the first neutralization tank and the second neutralization tank; The emulsion wastewater treatment unit includes an emulsion wastewater equalization tank, an oil separator, a demulsification tank, an emulsion neutralization tank, an emulsion coagulation tank, an emulsion flocculation tank, and an emulsion flotation tank connected in sequence. The emulsion wastewater equalization tank is used for homogenizing and equalizing the emulsion wastewater; the oil separator is used for preliminary oil-water separation of the emulsion wastewater; the demulsification tank is used for breaking down the emulsion in the emulsion wastewater; the emulsion neutralization tank is used to adjust the pH of the emulsion wastewater to 6.5-7.5; the emulsion coagulation tank is used to coagulate suspended solids in the emulsion wastewater; the emulsion flocculation tank is used to flocculate suspended solids in the emulsion wastewater; the emulsion flotation tank is used to reduce the total oil content in the emulsion wastewater and obtain the primary emulsion wastewater; the emulsion flotation tank is connected to the alkaline oily wastewater equalization tank. The leveling liquid wastewater treatment unit includes a leveling liquid wastewater equalization tank, an acidification tank, a leveling liquid neutralization tank, a leveling liquid coagulation tank, a leveling liquid flocculation tank, and a leveling liquid air flotation tank connected in sequence. The leveling liquid wastewater equalization tank is used to homogenize and adjust the leveling liquid wastewater; the acidification tank is used to acidify the leveling liquid wastewater; the leveling liquid neutralization tank is used to adjust the pH of the emulsion wastewater to 6.5~7.5; the leveling liquid coagulation tank is used to coagulate the suspended solids in the leveling liquid wastewater; and the leveling liquid flocculation tank is used to flocculate the suspended solids in the leveling liquid wastewater. The leveling liquid flotation tank is used to reduce the total oil content in the leveling liquid wastewater and obtain the first-stage leveling liquid wastewater; the leveling liquid flotation tank is connected to the alkaline oily wastewater equalization tank; The acidification tank is connected to the acidic wastewater equalization tank.

2. The wastewater reuse and treatment system for cold-rolled carbon steel as described in claim 1, characterized in that, The alkaline oily wastewater treatment unit further includes at least one neutralization tank, which is connected to the acidic wastewater treatment unit. The at least one neutralization tank is used to neutralize the primary acidic wastewater and the primary mixed wastewater to obtain the primary mixed wastewater.

3. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 2, characterized in that, The alkaline oily wastewater treatment unit further includes a mixing and flocculation treatment module, an air flotation treatment module, and a biochemical treatment module. The mixing and flocculation treatment module is used to mix and flocculate the suspended solids in the primary mixed wastewater and cause the suspended solids in the primary mixed wastewater to settle. The air flotation treatment module is used to mix and flocculate the suspended solids in the primary mixed wastewater a second time and reduce the total oil content in the primary mixed wastewater. The biochemical treatment module is used to reduce the organic matter in the primary mixed wastewater and obtain the secondary mixed wastewater.

4. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 3, characterized in that, The mixed flocculation treatment module includes a first coagulation tank, a first flocculation tank, and a sedimentation tank connected in sequence. The first coagulation tank is used to perform preliminary coagulation of suspended solids in the primary mixed wastewater, the first flocculation tank is used to perform preliminary flocculation of suspended solids in the primary mixed wastewater, and the sedimentation tank is used to settle suspended solids in the primary mixed wastewater.

5. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 4, characterized in that, The dissolved air flotation (DAF) treatment module includes a second coagulation tank, a second flocculation tank, and a DAF tank connected in sequence. The second coagulation tank is used for secondary coagulation of suspended solids in the primary mixed wastewater, the second flocculation tank is used for secondary flocculation of suspended solids in the primary mixed wastewater, and the DAF tank is used to reduce the total oil content in the primary mixed wastewater.

6. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 5, characterized in that, The biochemical treatment module includes an anoxic tank, an aerobic tank, and an MBR membrane bioreactor. The anoxic tank is connected to the dissolved air flotation tank. The anoxic tank is used for denitrification of the primary mixed wastewater. The aerobic tank is used to degrade COD and ammonia nitrogen in the primary mixed wastewater. The MBR membrane bioreactor is used to retain suspended solids and organic matter in the primary mixed wastewater.

7. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 6, characterized in that, The emulsion wastewater treatment unit includes an emulsion wastewater equalization tank, an oil separator, a demulsification tank, an emulsion neutralization tank, an emulsion coagulation tank, an emulsion flocculation tank, and an emulsion flotation tank connected in sequence. The emulsion wastewater equalization tank is used to homogenize and regulate the emulsion wastewater; the oil separator is used to perform preliminary oil-water separation in the emulsion wastewater; the demulsification tank is used to break up the emulsion in the emulsion wastewater; the emulsion neutralization tank is used to adjust the pH of the emulsion wastewater to 6.5-7.5; the emulsion coagulation tank is used to coagulate the suspended solids in the emulsion wastewater; the emulsion flocculation tank is used to flocculate the suspended solids in the emulsion wastewater; and the emulsion flotation tank is used to reduce the total oil content in the emulsion wastewater and obtain the primary emulsion wastewater. The emulsion flotation tank is connected to the alkaline oily wastewater equalization tank.

8. The wastewater reuse and treatment system for cold-rolled carbon steel according to claim 7, characterized in that, The acidification tank is connected to the acidic wastewater equalization tank.

9. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 8, characterized in that, The wastewater reuse treatment unit includes an intermediate water tank, a booster pump, a security filter, and a reverse osmosis device connected in sequence. The intermediate water tank is used to receive the secondary mixed wastewater; the booster pump is used to pressurize the secondary mixed wastewater; the security filter is used to remove residual suspended solids in the secondary mixed wastewater; and the reverse osmosis equipment is used to desalinate the secondary mixed wastewater.

10. The wastewater reuse and treatment system for cold-rolled plain carbon steel according to claim 9, characterized in that, The wastewater reuse treatment system for cold-rolled carbon steel also includes a sludge dewatering unit. The sludge dewatering unit has an inlet, a first outlet, and a second outlet. The inlet is connected to the emulsion flotation tank, the leveling liquid flotation tank, the sedimentation tank, the flotation tank, and the MBR membrane bioreactor. The first outlet is connected to the alkaline oily wastewater equalization tank, and the second outlet is connected to the sludge cake storage tank.

11. A wastewater reuse treatment process for cold-rolled carbon steel, characterized in that, The wastewater reuse treatment process for cold-rolled plain carbon steel is applicable to the wastewater reuse treatment system for cold-rolled plain carbon steel as described in claim 9, and includes the following steps: Acidic wastewater is transported to the acidic wastewater treatment unit for treatment to obtain the primary acidic wastewater; emulsion wastewater is transported to the emulsion wastewater treatment unit for treatment to obtain the primary emulsion wastewater; leveling liquid wastewater is transported to the leveling liquid wastewater treatment unit for treatment to obtain the primary leveling liquid wastewater; The primary emulsified wastewater and the primary leveling liquid wastewater are transported to the alkaline oily wastewater equalization tank and mixed with the alkaline oily wastewater entering the alkaline oily wastewater equalization tank to obtain the primary mixed wastewater. The primary acidic wastewater is transported to the first neutralization tank and neutralized with the primary mixed wastewater in the first neutralization tank to obtain the primary mixed wastewater; The primary mixed wastewater is transported to the second neutralization tank, and a pH adjuster is added to adjust the pH of the primary mixed wastewater to 6.5~7.5; The effluent from the second neutralization tank is fed into the alkaline oily wastewater treatment unit for mixing and flocculation, flotation and biochemical treatment to obtain the secondary mixed wastewater. The secondary mixed wastewater is transported to the wastewater reuse treatment unit for desalination to obtain desalinated water and concentrated brine.

12. The wastewater reuse treatment process for cold-rolled carbon steel according to claim 11, characterized in that, When the pH of the primary mixed wastewater is less than 6.5, the added pH adjuster is sodium hydroxide or sodium carbonate or a combination of both; when the pH of the primary mixed wastewater is greater than 7.5, the added pH adjuster is the primary acidic wastewater or hydrochloric acid or a combination of both.

13. The wastewater reuse treatment process for cold-rolled carbon steel according to claim 11, characterized in that, The wastewater reuse treatment process for cold-rolled carbon steel also includes: aeration treatment of the waste acid emergency conditioning tank, the acidic wastewater conditioning tank, the first neutralization tank and the second neutralization tank, in order to oxidize the ferrous ions in the wastewater to ferric ions.

14. The wastewater reuse treatment process for cold-rolled plain carbon steel according to claim 13, characterized in that, The wastewater reuse treatment process for cold-rolled carbon steel also includes: aerating the alkaline oily wastewater regulating tank to prevent the sedimentation of suspended solids in the primary mixed wastewater.

15. The wastewater reuse treatment process for cold-rolled carbon steel according to claim 14, characterized in that, The wastewater reuse treatment process for cold-rolled carbon steel also includes: using contact oxidation technology to aerate both the aerobic tank and the MBR membrane bioreactor to degrade COD and ammonia nitrogen in the primary mixed wastewater.

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