Biochemical cooperative treatment system and method for degreasing multi-component coating waste liquid

Abstract

The treatment system comprises an oil-water separation device, an ozone homogenizing tank, an adjusting tank, an air floatation tank and an aerobic biochemical device, the oil-water separation device is provided with a degreasing waste liquid inlet, and a water outlet of the oil-water separation device is connected with the ozone homogenizing tank; the ozone homogenizing tank is provided with an other waste liquid inlet, a water outlet of the ozone homogenizing tank is connected with the regulating tank, and the regulating tank is used for removing phosphorus and zinc and preliminarily destabilizing emulsified oil and resin colloid; a water outlet of the regulating tank is connected with the air floatation tank, the air floatation tank is used for enhancing coagulation clarification and deep removal of pollutants, a microbial filler is arranged in the aerobic biochemical device and is used for biologically metabolizing and degrading organic matters, and a water outlet of the air floatation tank is connected with the aerobic biochemical device. Through cooperative treatment, the dosage is saved, the treatment efficiency is improved, the effect of cooperative demulsification and oil removal is achieved, and the follow-up treatment load and the dosage of chemicals are reduced.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and more specifically, to a biochemical synergistic treatment system and method for degreasing multi-component coating waste liquid. Background Technology

[0002] With increasingly stringent national environmental protection requirements, the coating industry faces increasingly stringent emission standards for water treatment, especially in the automotive manufacturing sector, where wastewater generated during coating processes is characterized by complex composition, high pollutant concentrations, and poor biodegradability. Coating production lines mainly include pretreatment, electrophoresis, intermediate coating, and topcoat processes. The pretreatment stage involves multiple chemical treatment processes such as degreasing, pickling, and phosphating. Each stage generates a large amount of high-concentration wastewater during tank cleaning and subsequent rinsing. Specifically, this includes degreasing wastewater from the degreasing stage, waste acid from the pickling stage, phosphating wastewater from the phosphating stage, and a small amount of paint wastewater from the spraying process. These wastewaters contain high concentrations of chemical oxygen demand (CODcr), suspended solids (SS), oils, phosphates (as phosphorus), anionic surfactants (LAS), and heavy metal zinc (Zn). 2+ Pollutants such as ) are typical examples of difficult-to-treat industrial wastewater.

[0003] Currently, the industry generally uses physicochemical or biochemical methods for treatment, with some companies still employing traditional coagulation sedimentation, flotation, Fenton oxidation, or conventional biochemical treatment processes. However, due to the significant differences in the properties of various waste liquids, pollutants interfere with each other after mixing, making it difficult for a single treatment process to cope with water quality fluctuations. The system has weak shock resistance and poor operational stability, often failing to achieve stable discharge compliance. Furthermore, to meet the latest emission standards or reuse requirements, companies need to invest more in reagents and energy, further increasing their operational burden. This is especially true for small and medium-sized coating enterprises, who face a severe challenge in balancing environmental compliance pressures with economic cost control. Therefore, under current technological conditions, effectively addressing the treatment challenges of high-concentration, multi-component coating waste liquids has become one of the key bottlenecks restricting the sustainable development of the industry.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a biochemical co-treatment system and method for degreasing multi-component coating waste liquid, so as to improve the above-mentioned technical problems.

[0006] This invention is implemented as follows: In a first aspect, the present invention provides a multi-component coating waste liquid degreasing biochemical co-treatment system, comprising: The oil-water separation device is equipped with a degreasing waste liquid inlet; The ozone homogenizing tank is connected to the outlet of the oil-water separation device, and the ozone homogenizing tank is equipped with other waste liquid inlets. An equalization tank is used for phosphorus and zinc removal, as well as preliminary destabilization of emulsified oil and resin colloids. The outlet of the ozone homogenizing tank is connected to the equalization tank. An air flotation tank is used to enhance coagulation clarification and deep removal of pollutants, and the outlet of the equalization tank is connected to the air flotation tank. An aerobic biochemical device is provided, which contains microbial packing material for the biological metabolism and degradation of organic matter. The outlet of the flotation tank is connected to the aerobic biochemical device.

[0007] In an optional embodiment, it further includes a precision feeding system, which includes a first acid-base regulator addition pipe, a second acid-base regulator addition pipe, a first flocculant addition pipe, a second flocculant addition pipe, a first coagulant addition pipe, a second coagulant addition pipe, a first demulsifier addition pipe, a second demulsifier addition pipe, and a dedicated phosphorus removal agent addition pipe; the equalization tank is connected to the first acid-base regulator addition pipe, the first flocculant addition pipe, the first coagulant addition pipe, the first demulsifier addition pipe, and the dedicated phosphorus removal agent addition pipe, respectively; the flotation tank is connected to the second acid-base regulator addition pipe, the second flocculant addition pipe, the second coagulant addition pipe, and the second demulsifier addition pipe, respectively.

[0008] In an optional embodiment, the oil-water separation device is an oil-water separation tank, the degreasing waste liquid inlet is located at the top of the oil-water separation tank, an oil separator is provided at the top of the oil-water separation tank, and a first lift pump is provided at the bottom of the oil-water separation tank. The first lift pump is connected to the ozone homogenization tank through a pipeline.

[0009] In an optional embodiment, the bottom of the ozone homogenizing tank is provided with a plurality of evenly distributed ozone nozzles, each of which is connected to an ozone generator outside the ozone homogenizing tank.

[0010] In an optional embodiment, a primary sedimentation tank is further provided between the equalization tank and the flotation tank, and a first agitator is provided at the bottom of the equalization tank.

[0011] In an optional embodiment, the aerobic biochemical device includes a first aerobic treatment section and a second aerobic treatment section. The sewage inlet is located in the first aerobic treatment section, and a second stirrer is located at the bottom of the first aerobic treatment section. Multiple oxygen-containing gas nozzles are located at the bottom of the second aerobic treatment section, and a return pump is also located at the bottom of the second aerobic treatment section. The return pump is connected to a return pipe extending to the first aerobic treatment section and a sewage discharge pipe connected to the sludge tank.

[0012] In an optional embodiment, it further includes a secondary sedimentation tank, wherein the outlet of the aerobic biological treatment device is connected to the secondary sedimentation tank, and the upper part of the secondary sedimentation tank is provided with a qualified water discharge outlet.

[0013] In an optional embodiment, it further includes a sludge tank, the top of which is provided with a sludge removal device and a sludge outlet, the sludge outlet being connected to the sludge tank, and the bottom of both the primary sedimentation tank and the secondary sedimentation tank being provided with sludge discharge pumps, the sludge discharge pumps being connected to the sludge tank via pipelines.

[0014] Secondly, the present invention provides a method for the biochemical co-treatment of degreasing of multi-component coating wastewater. This method employs a biochemical co-treatment system for degreasing of multi-component coating wastewater as described in any of the preceding embodiments. The degreasing wastewater from the multi-component coating wastewater is separated into oil and water using an oil-water separator, and then introduced together with the remaining wastewater into the ozone homogenizing tank for homogenization. The homogenized wastewater then enters the equalization tank, where a first acid-base regulator, a first flocculant, a first coagulant, a first demulsifier, and a special phosphorus removal agent are added for sedimentation treatment. After sedimentation, the wastewater is transferred to the flotation tank, where a second acid-base regulator, a second flocculant, a second coagulant, and a second demulsifier are added to complete the flotation coagulation reaction. Finally, the wastewater after the physicochemical reaction is introduced into an aerobic biochemical treatment device for microbial aerobic treatment.

[0015] In an optional embodiment, the first acid-base adjuster is 0.5~1 mg / L hydrochloric acid, the first flocculant is 20~25 mg / L polyaluminum chloride solution, the first coagulant is 1~2 mg / L polyacrylamide solution, the first demulsifier is 8~15 mg / L lime milk, the second acid-base adjuster is 0.5~1.5 mg / L hydrochloric acid, the second flocculant is 20~30 mg / L polyaluminum chloride solution, the second coagulant is 0.5~1 mg / L polyacrylamide solution, and the second demulsifier is 5~15 mg / L lime milk.

[0016] This invention offers the following advantages: By developing a wastewater treatment system that integrates physicochemical and biochemical processes, this system incorporates multiple chemical reaction processes. Intermediate products generated in each reaction stage can be directly used as reactants in subsequent reactions, achieving cascade utilization of reactants. Through the organic synergy of physicochemical and biochemical processes, the amount of reagents added is significantly reduced, while overall treatment efficiency is improved. Furthermore, the innovative introduction of an ozone homogenizing tank effectively enhances the hydrolysis and acidification process of organic matter in the wastewater, significantly increasing the B / C (biodegradability) ratio of the effluent and improving the operational efficiency of subsequent biological treatment units. The ozone also effectively inhibits the growth and reproduction of sulfate-reducing bacteria, thereby reducing the generation of toxic and harmful gases such as hydrogen sulfide, protecting the biological activity of acid-producing bacteria, and maintaining the stable operation of the entire biological treatment system. In addition, the equipment achieves synergistic demulsification and oil removal functions in the pretreatment stage, effectively reducing the content of emulsified oil and suspended solids in the wastewater, alleviating the load on subsequent treatment units, and further reducing reagent consumption. The entire system adopts a highly integrated design with a compact structure, facilitating centralized monitoring and operation management, and significantly reducing the technical difficulty and operating costs of daily maintenance. Therefore, this multi-component coating waste liquid degreasing and biochemical co-treatment system has advantages such as high treatment efficiency, stable operation, energy saving and consumption reduction, and simple maintenance, and is suitable for the efficient treatment and resource utilization of complex coating waste liquids. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the multi-component coating waste liquid degreasing and biochemical co-treatment system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the pretreatment section of the multi-component coating waste liquid degreasing and biochemical co-treatment system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the physicochemical treatment section of the multi-component coating waste liquid degreasing and biochemical co-treatment system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the precise feeding system of the multi-component coating waste liquid degreasing and biochemical co-treatment system according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the aerobic biochemical treatment device of the multi-component coating waste liquid degreasing and biochemical synergistic treatment system according to an embodiment of the present invention.

[0019] Icons: 10-Multi-component coating wastewater degreasing and biochemical co-treatment system; 100-Oil-water separator; 101-Degreasing wastewater inlet; 110-Separator; 120-Oil separator; 130-First lift pump; 140-First valve; 200-Ozone homogenization tank; 201-Other wastewater inlet; 210-Ozone generator; 220-Ozone nozzle; 230-Second valve; 240-Second lift pump; 250-Third valve; 300-Equalization tank; 310-First agitator; 400-Air flotation tank; 410-Sludge scraper; 500-Aerobic biochemical treatment device; 510-First aerobic treatment section; 520-Second aerobic treatment section; 530-Second agitator; 540-Oxygen-containing gas nozzle; 550 - Partition wall; 560 - Return pump; 600 - Precision feeding system; 601 - Acid-base regulator storage tank; 602 - Flocculant storage tank; 603 - Coagulant storage tank; 604 - Demulsifier storage tank; 605 - Special phosphorus removal agent storage tank; 610 - First acid-base regulator addition pipe; 620 - Second acid-base regulator addition pipe; 630 - First flocculant addition pipe; 640 - Second flocculant addition pipe; 650 - First coagulant addition pipe; 660 - Second coagulant addition pipe; 670 - First demulsifier addition pipe; 680 - Second demulsifier addition pipe; 690 - Special phosphorus removal agent addition pipe; 700 - Primary sedimentation tank; 800 - Sludge tank; 810 - Sludge discharge pump; 820 - Third agitator; 900 - Secondary sedimentation tank. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Reagents or instruments used, unless otherwise specified, are all conventional products that can be purchased commercially.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] Furthermore, the terms "first," "second," and "third" are used only for distinguishing descriptions and should not be interpreted as indicating or implying relative importance.

[0025] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0026] The following detailed description of the overall structure, working principle, and technical effects of the multi-component coating waste liquid degreasing and biochemical co-treatment system 10 provided by the present invention, through embodiments and in conjunction with the accompanying drawings, illustrates these aspects.

[0027] See Figure 1 This embodiment provides a multi-component coating wastewater degreasing biochemical co-treatment system 10, which includes: an oil-water separation device 100, an ozone homogenizing tank 200, an equalization tank 300, an air flotation tank 400, and an aerobic biochemical device. The oil-water separation device is equipped with a degreasing wastewater inlet 101; the outlet of the oil-water separation device 100 is connected to the ozone homogenizing tank 200, and the ozone homogenizing tank 200 is equipped with other wastewater inlets 201; the outlet of the ozone homogenizing tank 200 is connected to the equalization tank 300, which is used for phosphorus and zinc removal and preliminary destabilization of emulsified oil and resin colloids; the outlet of the equalization tank 300 is connected to the air flotation tank 400, which is used for enhanced coagulation clarification and deep removal of pollutants; the aerobic biochemical device is equipped with microbial packing material for biological metabolic degradation of organic matter, and the outlet of the air flotation tank 400 is connected to the aerobic biochemical device.

[0028] Specifically, see Figure 2 In this embodiment, the oil-water separation device 100 and the ozone homogenization tank 200 together constitute the pretreatment section. The degreasing wastewater, pickling wastewater, and phosphating wastewater generated in the coating process are non-continuously discharged wastewaters, and their pollutant concentrations are significantly higher than those of conventional wastewater. Among them, the degreasing wastewater needs to be specially collected and introduced into the oil-water separation device 100 for preliminary oil removal treatment, and then transported together with other wastewaters to the ozone homogenization tank 200 for centralized treatment.

[0029] The oil-water separation device 100 is an oil-water separation tank. Degreasing waste liquid is introduced into the oil-water separation tank through a pipe from the degreasing waste liquid inlet 101. The oil-water separation tank is usually a cuboid or cylindrical structure, and the material is carbon steel (with an anti-corrosion lining), stainless steel, or fiberglass. The volume and length-width-height ratio are designed according to the processing capacity. A drain outlet is reserved at the bottom of the tank for cleaning the deposited sludge and impurities. A partition plate 110 is installed vertically inside the tank, dividing the tank into an inlet area (one side) and an outlet area. (On the other side), the bottom of the partition plate 110 and the bottom of the tank are kept at a certain gap (about 10% to 20% of the height of the tank). The water supply flows from the bottom of the inlet area to the outlet area. The top of the partition plate 110 is lower than the upper edge of the tank to prevent the oil phase from directly entering the outlet area with the water flow. The partition plate 110 is made of the same material as the tank and has a smooth surface to reduce oil and water adhesion. In some working conditions, a guide plate can be installed on the side of the partition plate 110 facing the inlet area to guide the water flow to rise evenly and prevent local turbulence from damaging the oil and water separation.

[0030] An oil separator 120 is installed at the top of the inlet side of the partition plate 110, which is sealed to the upper edge of the tank and covers the oil-rich area at the top of the inlet area. The oil separator 120 can be a weir-type oil separator 120, a tubular oil skimmer, or a rotary oil skimmer 120, etc. A first lift pump 130 is installed at the bottom of the outlet side of the partition plate 110, which is used to lift the oil-separated wastewater through a pipeline and pump it into the top of the ozone homogenizing tank 200. A first valve 140 is also installed on the pipeline to control the flow rate. The first valve 140 can be a solenoid valve, etc.

[0031] Pickling wastewater, phosphating wastewater, and other wastewater from the painting process are introduced into the ozone homogenizing tank 200 through the other wastewater inlet 201 at the top. In this embodiment, the ozone homogenizing tank 200 is rectangular, but in other embodiments it can be cylindrical, etc. Its material must be resistant to the strong oxidizing properties of ozone; commonly used materials include stainless steel (304 / 316L), fiberglass (FRP), and carbon steel with an anti-corrosion coating. A sealed cover is installed at the top of the tank to prevent ozone leakage. The cover has a reserved inspection port and an exhaust gas collection port. The bottom of the tank is treated to prevent water leakage. The bottom of the ozone homogenizing tank 200 is also equipped with an air distribution system to disperse the ozone gas generated by the ozone generator 210 into tiny bubbles, which are evenly introduced into the bottom of the tank to maximize the gas-liquid contact area. Specifically, the bottom of the ozone homogenization tank 200 is equipped with multiple evenly distributed ozone nozzles 220. Each ozone nozzle 220 is connected to an ozone generator 210 outside the ozone homogenization tank 200 via a pipe. A second valve 230 is installed on the pipe through which the ozone generator 210 vents to control the amount of ozone introduced. The second valve 230 can be a solenoid valve. The bottom of the ozone homogenization tank 200 is connected to a second lift pump 240 via a pipe for introducing the treated wastewater into the equalization tank 300. It should be noted that there can be two second lift pumps 240, one in operation and one on standby. A third valve 250 is installed on the pipe leading into the equalization tank 300 to control the flow rate.

[0032] The ozone homogenizing tank 200 employs an ozone aeration process (dosage of 0.5~2 mg / L). While achieving hydrolysis and acidification, the strong oxidizing effect of ozone causes chain-breaking and ring-opening reactions of resinous substances, benzene compounds, and high-molecular-weight organic matter in the wastewater, converting them into small-molecule organic acids such as acetic acid and propionic acid. This process significantly improves the B / C ratio of the wastewater, creating favorable conditions for subsequent biological treatment. Furthermore, this process effectively inhibits the activity of sulfate-reducing bacteria, reduces the generation of toxic substances such as hydrogen sulfide, ensures the biological activity of acid-producing bacteria, and maintains the stable operation of the treatment system. Simultaneously, the acidic environment demulsifies and removes residual oils in the wastewater, reducing the load on subsequent treatment units and decreasing the amount of chemical reagents required.

[0033] See Figure 3In this embodiment, the equalization tank 300 and the flotation tank 400 together constitute the physicochemical treatment section. A first agitator 310 is installed at the bottom of the equalization tank 300 to ensure that the waste liquid reacts fully with the reagents. In this embodiment, a primary sedimentation tank 700 is also provided between the equalization tank 300 and the flotation tank 400. An overflow outlet is provided at the top of the equalization tank 300, communicating with the primary sedimentation tank 700. An overflow outlet is also provided at the top of the primary sedimentation tank 700, communicating with the flotation tank 400. A baffle with a certain inclination angle (e.g., 45 degrees) is provided above the primary sedimentation tank 700, below the overflow outlet. The primary sedimentation tank 700 is used to remove larger suspended solids (SS) from wastewater, achieving solid-liquid separation through gravity sedimentation. The baffle above is a key structure to enhance the sedimentation effect, effectively preventing scum from entering the flotation tank 400 with the water flow. A scraper 410 is installed at the top of the flotation tank 400. In this embodiment, the scraper 410 is a chain scraper. The flotation tank 400 is also equipped with a conventional dissolved air system and a dissolved air release component at the bottom (not shown). An outlet is provided at the bottom of the flotation tank 400, and the treated wastewater is pumped into the aerobic biological treatment device 500 by a suction pump.

[0034] See Figure 1 and Figure 4 This embodiment also includes a precision feeding system 600, which includes an acid-base regulator storage tank 601, a flocculant storage tank 602, a coagulant storage tank 603, a demulsifier storage tank 604, and a dedicated phosphorus removal agent storage tank 605, all connected to a tap water pipe. It also includes a first acid-base regulator addition pipe 610, a second acid-base regulator addition pipe 620, a first flocculant addition pipe 630, a second flocculant addition pipe 640, a first coagulant addition pipe 650, and a second coagulant addition pipe 6664, all connected to the corresponding storage tanks. 60. A first demulsifier addition pipe 670, a second demulsifier addition pipe 680, and a special phosphorus removal agent addition pipe 690 are provided. The equalization tank 300 is connected to the first acid-base regulator addition pipe 610, the first flocculant addition pipe 630, the first coagulant addition pipe 650, the first demulsifier addition pipe 670, and the special phosphorus removal agent addition pipe 690, respectively. The flotation tank 400 is connected to the second acid-base regulator addition pipe 620, the second flocculant addition pipe 640, the second coagulant addition pipe 660, and the second demulsifier addition pipe 680, respectively. For example, the first acid-base adjuster is 0.5~1 mg / L hydrochloric acid, the first flocculant is 20~25 mg / L polyaluminum chloride solution, the first coagulant is 1~2 mg / L polyacrylamide solution, the first demulsifier is 8~15 mg / L lime milk, the second acid-base adjuster is 0.5~1.5 mg / L hydrochloric acid, the second flocculant is 20~30 mg / L polyaluminum chloride solution, the second coagulant is 0.5~1 mg / L polyacrylamide solution, and the second demulsifier is 5~15 mg / L lime milk.

[0035] In this embodiment, the core purpose of the equalization tank 300 is to achieve deep chemical phosphorus removal, zinc ion fixation, and preliminary destabilization of emulsified oil and resin colloids. This is achieved through the synergistic effect of multiple agents to transform pollutant speciation. Lime slurry plays a dual role in pH control and precipitant supply: adding lime slurry raises the wastewater pH to 8-10, which is the optimal reaction range for calcium salt phosphorus removal and zinc ion hydroxide precipitation. Phosphate precipitation: Ca2+ dissociated from lime slurry... 2+ With PO4 in water 3- Combined, hydroxyapatite precipitate is formed; under alkaline conditions, Zn 2+ With OH - Zinc hydroxide precipitate is formed, Ca 2+ As a high-valence cation, PAC can compress the electric double layer of emulsified oils and polymer resin colloids through electron neutralization, weakening the repulsive forces between colloidal particles and causing them to change from a stable dispersed state to a destabilized state "to be flocculated". PAC hydrolysis generates polynuclear aluminum hydroxyl complexes, which, on the one hand, aggregate the destabilized colloidal particles into tiny flocs through adsorption bridging; on the other hand, the dissociated Al... 3+ With the remaining PO4 3- Aluminum phosphate precipitate is generated, further enhancing the phosphorus removal effect. Specialized phosphorus removal agents (mostly composite agents such as polyferric salts and aminotrimethylene phosphonic acid) can specifically capture hypophosphite and organic phosphorus in water that are difficult to remove by calcium and aluminum salts. Through chelation and complexation, stable phosphate precipitates are formed, compensating for the shortcomings of conventional chemical phosphorus removal. As an organic polymeric flocculant, PAM uses the adsorption and bridging effect of long molecular chains to "connect" tiny particles of hydroxyapatite, zinc hydroxide, aluminum phosphate, and destabilized colloids into large and dense flocs, accelerating solid-liquid separation. A small amount of hydrochloric acid is added to precisely control the upper limit of pH, avoiding excessive lime slurry that could cause the pH to exceed 10, thus preventing increased difficulty in subsequent adjustment in the flotation tank (400°C). It also inhibits the formation of calcium carbonate by-precipitates, reducing agent waste.

[0036] After the wastewater enters the 400-ton dissolved air flotation (DAF) tank, a second addition of reagents enhances the coagulation reaction. Combined with the DAF interception effect, this further removes COD and SS. Hydrochloric acid and lime slurry are added to fine-tune the pH to the optimal range for the DAF process. This ensures that PAC hydrolyzes to form highly efficient flocculent aluminum hydroxyl complexes while preventing excessively high or low pH levels from causing floc restabilization. Supplemental PAC (20-30 mg / L) provides high-valence cations, which neutralize the negative charge of residual colloids and, through sweeping action, encapsulate incompletely settled fine particles within the flocs, improving pollutant removal rates. Low-dose PAM (0.5-1 mg / L) bridging through adsorption makes the floc structure denser and improves the adhesion between the flocs and the air flotation bubbles. After the bubbles adhere to the floc surface, the overall density of the flocs decreases, causing them to quickly float to the surface and form scum, achieving solid-liquid separation and thus removing some COD (colloidal organic matter) and SS. The emulsified oil and resin colloids that were not fully destabilized in the equalization tank 300 underwent secondary destabilization and coagulation in the coagulation environment of the flotation tank 400, and were eventually scraped off with the scum, further reducing the pollutant load of subsequent biochemical processes.

[0037] Therefore, to achieve efficient physicochemical treatment, the pH of the wastewater was controlled within the range of 8-10 by adjusting the amount of lime slurry added. This promoted the reaction of phosphate ions and calcium ions in the water to form hydroxyapatite precipitate, while zinc ions formed zinc hydroxide precipitate, thereby effectively removing phosphate and heavy metal ions and reducing the effluent phosphate concentration to below 5.0 mg / L. Furthermore, Ca²⁺ +The introduction of [the substance] also promotes the destabilization and coagulation of residual emulsified oil and polymeric resin colloidal substances, creating favorable conditions for subsequent coagulation reactions. Subsequently, the wastewater flows horizontally into the flotation tank 400, where hydrochloric acid, lime, PAC, and PAM are further added. Under the synergistic effect of these chemicals, the destabilized emulsified oil and colloidal particles undergo sufficient coagulation and flocculation reactions, forming flocs that can be effectively separated. Solid-liquid separation is achieved through flotation, significantly reducing the concentration of chemical oxygen demand (COD) and suspended solids (SS) in the wastewater. The main function of the physicochemical treatment section is to balance water quality and efficiently remove inorganic pollutants and some recalcitrant organic pollutants from the water, especially for the combined wastewater generated from phosphating, electrophoresis, and acid-base cleaning processes, effectively reducing most of the phosphates, metal ions, and colloidal pollutants. This process not only prevents large suspended or floating solids from entering the subsequent wastewater treatment system, avoiding blockages in key equipment such as pumps and pipes, but also reduces the shock load on the main treatment process by homogenizing the influent water quality, ensuring the stable operation of the biological system and ultimately ensuring that the effluent water quality consistently meets standards. The above process incorporates multiple chemical reactions, such as: acid-base adjustment reaction: 2HCl + Ca(OH)₂ = CaCl₂ + 2H₂O; phosphorus removal reaction with phosphorus removal agent: 3CaCl₂ + 2Na₃PO₄ = Ca₃(PO₄)₂↓ + 6NaCl and 3Ca(OH)₂ + 2H₃PO₄ = Ca₃(PO₄)₂↓ + 6H₂O; and the reaction of zinc ions with lime: Zn 2+ +Ca(OH)₂=Zn(OH)₂+Ca 2+ Demulsification reaction: R-COONa + HCl = R-COOH↓ + NaCl, CaCl2 + 2R-COONa = (R-COO)2Ca↓ + 2NaCl.

[0038] Further, see Figure 5 The aerobic biochemical device includes a first aerobic treatment section 510 and a second aerobic treatment section 520. The sewage inlet is located in the first aerobic treatment section 510, and a second agitator 530 is located at the bottom of the first aerobic treatment section 510. Multiple oxygen-containing gas nozzles 540 are located at the bottom of the second aerobic treatment section 520, and a return pump 560 is also located at the bottom of the second aerobic treatment section 520. The return pump 560 is connected to a return pipe extending to the first aerobic treatment section 510 and a sewage discharge pipe connected to the sludge tank 800.

[0039] Both the first aerobic treatment section 510 and the second aerobic treatment section 520 are uniformly equipped with microbial packing materials. The bottom agitator of the first aerobic section uses a low-speed paddle mixer (10-30 r / min) or a submersible pusher mixer. The paddle diameter is designed according to the width of the tank to ensure no dead zones in the mixing process, thus pushing the sludge to the second aerobic treatment section 520. The main function of the first aerobic treatment section 510 is to thoroughly mix the influent and returned sludge, maintaining a uniform sludge concentration within the tank; increasing water turbulence to promote contact between organic matter and microorganisms; preventing sludge settling; and maintaining a suspended microbial environment.

[0040] The first aerobic treatment section 510 and the second aerobic treatment section 520 are equipped with partition walls 550, and overflow outlets are provided at the bottom. The second aerobic section is the main area for organic matter degradation, integrating three major functions: aeration and oxygen supply, sludge return, and sewage discharge. Oxygen-containing gas nozzles 540 are evenly distributed on the bottom of the tank through an air distribution network, with a spacing of 0.8~1.2m, forming a fully covered aeration area; equipped with Roots blowers or centrifugal blowers, oxygen-containing gas (air or oxygen-enriched air) is provided, whose main function is to oxygenate the water and maintain the dissolved oxygen (DO) concentration in the tank at 2~4mg / L to meet the metabolic needs of aerobic microorganisms; the bubbles generated by aeration drive the water to rise, forming circulation and enhancing the contact efficiency between microorganisms and organic matter; microbubbles cut flocs and promote the dispersion of sludge particles.

[0041] The return pump 560 is a submersible sludge pump. One end of the return pipe is connected to the return pump 560, and the other end extends to the upper part of the first aerobic treatment section 510. A water distributor can be installed at the end of the return pipe to make the returned sludge spread evenly and increase the sludge concentration of the first aerobic section. One end of the discharge pipe is connected to the return pipe through a tee, and the other end is connected to the sludge tank 800. A regulating valve is installed on the discharge pipe to control the discharge of excess sludge.

[0042] Furthermore, in this embodiment, the multi-component coating waste liquid degreasing biochemical co-treatment system 10 also includes a secondary sedimentation tank 900. The outlet of the aerobic biochemical tank device is connected to the secondary sedimentation tank 900. The upper part of the secondary sedimentation tank 900 is provided with a qualified water discharge outlet. The structure of the secondary sedimentation tank 900 is similar to that of the primary sedimentation tank 700.

[0043] In this embodiment, see again Figure 3 The multi-component coating waste liquid degreasing biochemical co-treatment system 10 also includes a sludge tank 800, an air flotation tank 400 with a slag removal device and a slag outlet at the top, the slag outlet being connected to the sludge tank 800, and a sludge discharge pump 810 at the bottom of the primary sedimentation tank 700 and the secondary sedimentation tank 900, the sludge discharge pump 810 being connected to the sludge tank 800 via a pipeline, and a third agitator 820 at the bottom of the sludge tank 800.

[0044] In this embodiment, the method for treating wastewater using the multi-component coating wastewater degreasing biochemical synergistic system is as follows: the degreasing wastewater in the multi-component coating wastewater is separated into oil and water by the oil-water separator 100, and then introduced together with the remaining wastewater into the ozone homogenizing tank 200 for homogenization treatment. The mixed wastewater after homogenization treatment then enters the equalization tank 300, where a first acid-base regulator, a first flocculant, a first coagulant, a first demulsifier, and a special phosphorus removal agent are added for sedimentation treatment. After sedimentation, the wastewater is transferred to the flotation tank 400, where the flotation coagulation reaction is completed by adding a second acid-base regulator, a second flocculant, a second coagulant, and a second demulsifier. Then, the wastewater after the physicochemical reaction is introduced into the aerobic biochemical treatment device 500 for microbial aerobic treatment.

[0045] It should be noted that, due to differences in production processes, the dosage of the selected agents mentioned above needs to be determined based on actual requirements to ensure good results.

[0046] In summary, companies in the coating industry generally use only a single physicochemical method (physicochemical method) or biochemical method (biochemical method) to treat wastewater. However, due to the diverse types and complex composition of pollutants in wastewater, single treatment processes are poorly resistant to fluctuations in water quality, prone to system instability or even failure, resulting in effluent that is difficult to consistently meet discharge standards and incurring high operating costs. The system described in this invention is an integrated wastewater treatment system that combines physicochemical and biochemical processes. Through the orderly connection of multiple chemical reaction units, this system achieves the cascade utilization of reaction products. The products of previous reactions can serve as reaction conditions or promoting factors for subsequent reactions, significantly improving resource utilization efficiency. Through the synergistic optimization of physicochemical and biochemical processes, not only is the dosage of chemical reagents reduced, but the overall removal efficiency of pollutants is also significantly improved. Furthermore, the innovative introduction of an ozone homogenization tank 200 effectively enhances the hydrolysis and acidification process of wastewater, significantly improving the biodegradability (B / C ratio) of the wastewater and creating favorable conditions for subsequent biochemical treatment. Meanwhile, ozone effectively inhibits the proliferation of sulfate-reducing bacteria, reduces the production of toxic and harmful gases such as hydrogen sulfide, and protects the activity of acid-producing bacteria, thereby maintaining the stability and continuous operation of the biological treatment system. Furthermore, this co-treatment process achieves simultaneous demulsification and oil removal, effectively reducing the content of oil and colloidal pollutants in wastewater, significantly reducing the load on subsequent treatment units, and further reducing reagent consumption. The entire system adopts a highly integrated design, with a compact structure, facilitating centralized monitoring and operation management, significantly reducing the difficulty of system maintenance and the need for manual intervention.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-component coating waste liquid degreasing and biochemical co-treatment system, characterized in that, It includes: The oil-water separation device is equipped with a degreasing waste liquid inlet; The ozone homogenizing tank is connected to the outlet of the oil-water separation device, and the ozone homogenizing tank is equipped with other waste liquid inlets. An equalization tank is used for phosphorus and zinc removal, as well as preliminary destabilization of emulsified oil and resin colloids. The outlet of the ozone homogenizing tank is connected to the equalization tank. An air flotation tank is used to enhance coagulation clarification and deep removal of pollutants, and the outlet of the equalization tank is connected to the air flotation tank. An aerobic biochemical device is provided, which is equipped with microbial packing material for biological metabolism and degradation of organic matter. The outlet of the flotation tank is connected to the aerobic biochemical device.

2. The multi-component coating wastewater degreasing and biochemical co-treatment system according to claim 1, characterized in that, It also includes a precision feeding system, which comprises a first acid-base regulator addition pipe, a second acid-base regulator addition pipe, a first flocculant addition pipe, a second flocculant addition pipe, a first coagulant addition pipe, a second coagulant addition pipe, a first demulsifier addition pipe, a second demulsifier addition pipe, and a dedicated phosphorus removal agent addition pipe; the equalization tank is connected to the first acid-base regulator addition pipe, the first flocculant addition pipe, the first coagulant addition pipe, the first demulsifier addition pipe, and the dedicated phosphorus removal agent addition pipe, respectively; the flotation tank is connected to the second acid-base regulator addition pipe, the second flocculant addition pipe, the second coagulant addition pipe, and the second demulsifier addition pipe, respectively.

3. The multi-component coating wastewater degreasing and biochemical co-treatment system according to claim 1, characterized in that, The oil-water separation device is an oil-water separation tank. The degreasing waste liquid inlet is located at the top of the oil-water separation tank. An oil separator is installed at the top of the oil-water separation tank. A first lift pump is installed at the bottom of the oil-water separation tank. The first lift pump is connected to the ozone homogenization tank through a pipeline.

4. The multi-component coating wastewater degreasing and biochemical co-treatment system according to claim 1, characterized in that, The bottom of the ozone homogenizing tank is equipped with multiple evenly distributed ozone nozzles, each of which is connected to an ozone generator outside the ozone homogenizing tank.

5. The multi-component coating wastewater degreasing and biochemical co-treatment system according to claim 1, characterized in that, A primary sedimentation tank is also provided between the equalization tank and the flotation tank, and a first agitator is provided at the bottom of the equalization tank.

6. The multi-component coating waste liquid degreasing and biochemical co-treatment system according to claim 5, characterized in that, The aerobic biochemical device includes a first aerobic treatment section and a second aerobic treatment section. The sewage inlet is located in the first aerobic treatment section, and a second stirrer is located at the bottom of the first aerobic treatment section. Multiple oxygen-containing gas nozzles are located at the bottom of the second aerobic treatment section, and a return pump is also located at the bottom of the second aerobic treatment section. The return pump is connected to a return pipe extending to the first aerobic treatment section and a sewage discharge pipe connected to the sludge tank.

7. The multi-component coating waste liquid degreasing and biochemical co-treatment system according to claim 6, characterized in that, It also includes a secondary sedimentation tank, the outlet of the aerobic biological treatment device is connected to the secondary sedimentation tank, and the upper part of the secondary sedimentation tank is provided with a qualified water discharge outlet.

8. The multi-component coating waste liquid degreasing and biochemical co-treatment system according to claim 7, characterized in that, It also includes a sludge tank, and the top of the flotation tank is equipped with a sludge removal device and a sludge outlet, which is connected to the sludge tank. The bottom of the primary sedimentation tank and the secondary sedimentation tank are both equipped with sludge discharge pumps, which are connected to the sludge tank through pipelines.

9. A method for the biochemical co-treatment of multi-component coating wastewater, characterized in that, The system employs a multi-component coating waste liquid degreasing biochemical co-treatment system as described in any one of claims 1 to 8. The degreasing waste liquid from the multi-component coating waste liquid is separated into oil and water by an oil-water separator, and then introduced together with the remaining waste liquid into the ozone homogenizing tank for homogenization. The homogenized mixed waste liquid then enters the equalization tank, where a first acid-base regulator, a first flocculant, a first coagulant, a first demulsifier, and a special phosphorus removal agent are added for sedimentation treatment. After sedimentation, the waste liquid is transferred to the flotation tank, where a second acid-base regulator, a second flocculant, a second coagulant, and a second demulsifier are added to complete the flotation coagulation reaction. Finally, the waste liquid after the physicochemical reaction enters an aerobic biochemical treatment device for microbial aerobic treatment.

10. The method for degreasing and biochemical co-treatment of multi-component coating wastewater according to claim 9, characterized in that, The first acid-base adjuster is 0.5~1 mg / L hydrochloric acid, the first flocculant is 20~25 mg / L polyaluminum chloride solution, the first coagulant is 1~2 mg / L polyacrylamide solution, the first demulsifier is 8~15 mg / L lime milk, the second acid-base adjuster is 0.5~1.5 mg / L hydrochloric acid, the second flocculant is 20~30 mg / L polyaluminum chloride solution, the second coagulant is 0.5~1 mg / L polyacrylamide solution, and the second demulsifier is 5~15 mg / L lime milk.

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