Wastewater recovery treatment system for metal product cleaning

Abstract

The invention relates to a metal product cleaning wastewater recovery treatment system, which belongs to the field of wastewater recovery, and comprises a metal product cleaning process, a cleaning wastewater transmission unit, a pretreatment unit, a branching and shunting unit, a multi-stage coagulating sedimentation unit, a biochemical treatment unit, a deep treatment unit, a reuse water storage and distribution unit and an intelligent control and regulation unit. According to the wastewater recycling system for metal product cleaning, acid washing liquid and alkaline washing liquid in cleaning wastewater are precisely recycled through the quality-dividing and flow-dividing unit, after multi-stage coagulating sedimentation, biochemical treatment and deep treatment, recycled water can meet the requirement of a metal product fine cleaning procedure, the wastewater recycling rate exceeds 70%, and fresh water is greatly reduced; and meanwhile, the acid and alkali washing liquid is recycled, so that the investment of repreparation of the medicament is reduced, water resources can be saved for enterprises every year, the medicament cost can be saved by more than 30%, and the economic benefit is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater recycling technology, specifically to a wastewater recycling and treatment system for cleaning metal products. Background Technology

[0002] Metal product cleaning is a key process in industries such as machining, electroplating, and metallurgy. This process generates mixed wastewater containing oil, metal scraps, complexed heavy metal ions, acid and alkali cleaning solutions, and recalcitrant organic matter. Direct discharge of this wastewater not only wastes water resources but also causes serious pollution to the soil, water bodies, and other ecological environments. Therefore, a wastewater recycling and treatment system for metal product cleaning has become an essential requirement for the industry. Its core functions typically include wastewater collection and transmission, pretreatment and impurity removal, pollutant separation, water purification, and resource recovery. Through a combination of processes such as physical filtration, chemical coagulation, biodegradation, and membrane separation, the wastewater can be discharged in compliance with standards or reused, while reducing resource consumption and environmental costs.

[0003] Please refer to the announcement numbers (CN220317566U, a treatment system for pickling wastewater from a metal oxidation plant), (CN220283863U, a treatment system for pickling wastewater from stainless steel), and (CN118851343B). The aforementioned patents have the following problems: although they can improve effluent quality, they lack a separate acid / alkali washing solution recovery module, resulting in the inability to recycle the acid and alkali agents consumed during the cleaning process, increasing production costs; although sludge recovery is possible, the "drying + recycling" sludge disposal method results in low resource value, and a fully intelligent control system is not established. Parameter adjustments for units such as coagulation sedimentation and membrane separation rely on manual experience, making the treatment effect unstable due to water quality fluctuations; and although acid and heavy metals can be recovered, the process integration lacks a systematic design, failing to integrate deep oil removal and precise reclaimed water allocation functions, thus failing to meet the high water quality reuse requirements of the metal product washing process. This application proposes another technical solution to address these problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a wastewater recycling and treatment system for cleaning metal products. This system significantly reduces the use of fresh water and, through the recycling of acid and alkali cleaning solutions, reduces the investment in re-preparing chemicals. It can save enterprises more than 30% of water resources and chemical costs annually, significantly improving economic efficiency and solving the problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a wastewater recycling and treatment system for cleaning metal products, comprising a metal product cleaning process, a wastewater transmission unit, a pretreatment unit, a branch diversion unit, a multi-stage coagulation and sedimentation unit, a biochemical treatment unit, a deep treatment unit, a recycled water storage and distribution unit, and an intelligent control and regulation unit;

[0006] The metal product cleaning process is used to clean metal and generate metal product cleaning wastewater.

[0007] The wastewater transmission unit is used to collect and transmit the wastewater generated in the metal product cleaning process.

[0008] The pretreatment unit is used to adjust the water quality, remove oil and filter large particulate impurities in the wastewater from cleaning metal products.

[0009] The separation and diversion unit is used to separate and recover acidic and alkaline washing solutions from the cleaning wastewater.

[0010] The multi-stage coagulation and sedimentation unit is used to remove suspended solids, colloidal and complexed pollutants from wastewater.

[0011] The biochemical treatment unit is used to degrade organic pollutants in wastewater;

[0012] The advanced treatment unit is used to purify wastewater to the standard for cleaning and reuse of metal products.

[0013] The recycled water storage and distribution unit is used to store clean water and return it;

[0014] The intelligent control and regulation unit is used to monitor the operating parameters of each unit in real time and automatically adjust the process parameters.

[0015] The metal product cleaning process is connected to the cleaning wastewater transmission unit, the cleaning wastewater transmission unit is connected to the pretreatment unit, the pretreatment unit is connected to the separation and diversion unit, the separation and diversion unit is connected to the multi-stage coagulation and sedimentation unit, the effluent end of the multi-stage coagulation and sedimentation unit is connected to the biochemical treatment unit, the biochemical treatment unit is connected to the deep treatment unit, the deep treatment unit is connected to the recycled water storage and distribution unit, and the recycled water storage and distribution unit returns the recycled water to the metal product cleaning process.

[0016] The intelligent control and regulation unit is communicatively connected to the metal product cleaning process, the cleaning wastewater transmission unit, the pretreatment unit, the quality and flow separation unit, the multi-stage coagulation and sedimentation unit, the biochemical treatment unit, the deep treatment unit, and the recycled water storage and distribution unit.

[0017] Furthermore, the metal product cleaning process includes at least one metal product cleaning tank, which is equipped with a spray assembly for spraying cleaning liquid. After the cleaning liquid comes into contact with the metal product, it forms the metal product cleaning wastewater.

[0018] By implementing the above technical solution, the spray assembly can achieve uniform coverage and high-pressure rinsing of the cleaning liquid on the surface of metal products, which not only improves the cleanliness of oil and debris on the metal surface, but also reduces the amount of pollutant residue and reduces the treatment load of the subsequent wastewater pretreatment unit.

[0019] Furthermore, the pretreatment unit integrates a pH adjustment device, a temperature adjustment device, an air flotation oil removal component, and a precision filtration component; the pH adjustment device can adjust the pH of the wastewater to 6-9, the temperature adjustment device can adjust the temperature of the wastewater to 25-35℃, the air flotation oil removal component has an oil adsorption rate of ≥95%, and the precision filtration component can retain metal debris and fiber impurities of 5μm and above.

[0020] The above technical solution, with its multi-component integrated design, can simultaneously optimize wastewater quality, control temperature, and efficiently remove oil and large particulate impurities. This provides highly adaptable influent conditions for subsequent core processes such as separation and diversion, coagulation and sedimentation, significantly improving the overall system's treatment stability and efficiency.

[0021] Furthermore, the separation and diversion unit is controlled by a pH sensor and a solenoid valve; when the wastewater pH is ≤5, the acidic washing solution is retained and introduced into the acidic waste liquid storage tank; when the wastewater pH is ≥10, the alkaline washing solution is retained and introduced into the alkaline waste liquid storage tank; the monitoring accuracy of the acid / alkali washing solution concentration is ±1%, and the start / stop response time of the reuse pump is ≤5s.

[0022] The above technical solution, with its precise pH-linked interception, high-precision concentration monitoring, and rapid response design, can efficiently recover compliant acid / alkali washing solutions to reduce the cost of reagent re-preparation, while also avoiding treatment interference caused by the mixing of acid and alkali wastewater.

[0023] Furthermore, the multi-stage coagulation and sedimentation unit adopts a "first-stage coagulation-first-stage sedimentation-second-stage coagulation-second-stage sedimentation" process, sequentially adding polyaluminum chloride (dosage amount of 10-30 mg / L) and polyacrylamide (dosage amount of 0.5-2 mg / L); the first-stage sedimentation tank is an inclined tube sedimentation tank (inclination angle of 60°, surface loading of 1.0-1.5 m³ / (m²h)), and the second-stage sedimentation tank is a vertical flow sedimentation tank (upward flow velocity of 0.5-0.8 mm / s).

[0024] To achieve the above technical solution, the design of the staged coagulation and the parameters of the dedicated sedimentation tank can not only initially intercept a large amount of suspended solids through PAC and deeply capture colloidal and complexed pollutants through PAM, but also rely on the characteristics of efficient separation by inclined tube sedimentation and stable clarification by vertical flow sedimentation to increase the total pollutant removal rate to more than 85%, thereby reducing the organic load on the subsequent biochemical treatment unit.

[0025] Furthermore, the biochemical treatment unit adopts a "UASB anaerobic reactor + MBBR aerobic process"; the UASB anaerobic reactor has a volumetric loading rate of 2.0-4.0 kg COD / (m³d) and a reaction temperature of 35-38℃, with a COD removal rate of ≥70%; the MBBR aerobic process is filled with 30%-50% polyethylene suspended biological carrier, and the dissolved oxygen is controlled at 2-4 mg / L, with a further COD removal rate of ≥85%.

[0026] To achieve the above technical solution, the hierarchical and synergistic design of anaerobic degradation of high-concentration COD and aerobic deep purification, combined with the high volumetric load adaptability of UASB and the enhancement effect of MBBR biological carrier, can achieve a total COD removal rate of over 90%.

[0027] Furthermore, the advanced treatment unit adopts an "ozone (O3)-ultraviolet (UV) advanced oxidation + ultrafiltration + reverse osmosis" process; the O3 dosage is 10-20 mg / L, the UV wavelength is 254 nm, the light intensity is 80-120 mW / cm², and the mineralization rate of recalcitrant organic matter is ≥60%; the ultrafiltration uses a PVDF hollow fiber membrane (molecular weight cutoff 10000-30000 Da); the reverse osmosis uses a low-pressure reverse osmosis membrane, with an operating pressure of 1.0-1.5 MPa, a desalination rate of ≥98%, and a product water resistivity of ≥10 MΩcm.

[0028] The above technical solution achieves efficient mineralization of recalcitrant organic matter, retention of impurities and desalination through multi-process synergy, producing water that meets the standards for fine washing and reuse, ensuring stable and reliable quality of reclaimed water.

[0029] Furthermore, the recycled water storage and distribution unit includes a sterile clean water tank and an intelligent distribution module; the sterile clean water tank has a built-in ultraviolet disinfection device, and the total number of bacteria in the recycled water is ≤100 CFU / mL; the intelligent distribution module is linked with a flow meter and a solenoid valve, and can distribute recycled water according to the real-time water demand of the rough washing, fine washing and other processes in the metal product cleaning process, with a flow distribution accuracy of ≤5%.

[0030] The above technical solutions ensure the sterility and safety of reclaimed water through ultraviolet disinfection, and intelligently and accurately allocate water to meet the needs of different cleaning processes, thereby efficiently improving the utilization rate of reclaimed water and the adaptability of processes.

[0031] Furthermore, the multi-stage coagulation and sedimentation unit is also equipped with a sludge treatment unit and a resource utilization module; the sludge treatment unit is connected to the resource utilization module, the sludge treatment unit is used to treat the sludge generated by the multi-stage coagulation and sedimentation unit, and the resource utilization module is used to perform resource conversion on the sludge treatment products.

[0032] The above technical solutions, which integrate sludge treatment and resource utilization, reduce sludge volume while converting it into usable resources, thereby lowering solid waste disposal costs, reducing secondary pollution, and improving the system's environmental benefits.

[0033] Furthermore, the sludge thickening module uses a centrifugal thickener with a rotation speed of 3000-5000 r / min, concentrating the sludge moisture content from 99% to ≤95%; the sludge dewatering module uses a belt filter press with a cake moisture content ≤60%; the resource utilization module can mix dewatered sludge with clay and slag at a mass ratio of 3:5:2, granulate the mixture, and then calcine it at 800-1000℃ for 2-3 hours to produce ceramsite with a bulk density of 600-800 kg / m³, which is used as water treatment filter media or building filler.

[0034] The above technical solutions achieve efficient reduction of sludge moisture content through centrifugal concentration and belt filter press, and resource utilization through calcination to produce ceramsite, which reduces solid waste disposal costs and creates practical value.

[0035] Compared with the prior art, the present invention provides a wastewater recycling and treatment system for cleaning metal products, which has the following beneficial effects:

[0036] 1. This wastewater recycling and treatment system for metal product cleaning accurately recovers acidic and alkaline cleaning solutions from the cleaning wastewater through a separate flow unit. After multi-stage coagulation sedimentation, biochemical treatment, and deep treatment, the recycled water can meet the requirements of the fine cleaning process of metal products, with a wastewater reuse rate of over 70%, significantly reducing the need for fresh water. At the same time, the recycling of acid and alkaline cleaning solutions reduces the investment in the re-preparation of chemicals, saving enterprises more than 30% of water resources and chemical costs annually, significantly improving economic efficiency.

[0037] 2. This wastewater recycling and treatment system for metal product cleaning achieves total removal rates of over 95%, 90%, and 90% for oil, metal ions, and COD, respectively. The effluent consistently meets standards and can be reused at a high level. After resource recovery treatment, the sludge is made into ceramsite, reducing solid waste landfill volume by over 80% and preventing secondary pollution. Furthermore, the intelligent control unit can monitor and automatically adjust parameters of each unit in real time, reducing overall system energy consumption by 20%-25% and manual maintenance workload by over 50%, thus contributing to environmental protection and improving long-term operational stability and maintenance efficiency. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a wastewater recycling and treatment system for cleaning metal products proposed in this invention.

[0039] In the diagram: S101, metal product cleaning process; S102, cleaning wastewater transmission unit; S103, pretreatment unit; S104, branch diversion unit; S10A, multi-stage coagulation and sedimentation unit; S105, biochemical treatment unit; S106, deep treatment unit; S107, reclaimed water storage and distribution unit; S108, intelligent control and regulation unit; S201, sludge treatment unit; S202, resource utilization module. Detailed Implementation

[0040] 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.

[0041] Please see Figure 1 A wastewater recycling and treatment system for cleaning metal products includes a metal product cleaning process S101, a wastewater transmission unit S102, a pretreatment unit S103, a branch diversion unit S104, a multi-stage coagulation and sedimentation unit S10A, a biochemical treatment unit S105, a deep treatment unit S106, a recycled water storage and distribution unit S107, and an intelligent control and regulation unit S108.

[0042] In this embodiment, the metal product cleaning process S101 is used to clean the metal and generate metal product cleaning wastewater. The metal product cleaning process S101 includes at least one metal product cleaning tank. The cleaning tank is equipped with a spray assembly for spraying cleaning liquid. After the cleaning liquid comes into contact with the metal product, it forms metal product cleaning wastewater. The spray assembly can achieve uniform coverage and high-pressure rinsing of the surface of the metal product by the cleaning liquid, which not only improves the cleanliness of the oil and debris on the metal surface, but also reduces the amount of pollutant residue and reduces the processing load of the subsequent wastewater pretreatment unit S103.

[0043] Among them, the cleaning wastewater transmission unit S102 is used to collect and transmit the wastewater generated by the metal product cleaning process S101. The pretreatment unit S103 is used to adjust the water quality, remove oil and filter large particulate impurities in the metal product cleaning wastewater. The pretreatment unit S103 integrates a pH adjustment device, a temperature adjustment device, an air flotation oil removal component and a precision filter component. The pH adjustment device can adjust the pH of the wastewater to 6-9.

[0044] Specifically, the temperature control device can regulate the wastewater temperature to 25-35℃, the air flotation oil removal component has an oil adsorption rate of ≥95%, and the precision filtration component can intercept metal fragments and fibrous impurities of 5μm and above. The multi-component integrated design can simultaneously complete wastewater quality optimization, temperature control, and efficient removal of oil and large particulate impurities, providing highly adaptable influent conditions for subsequent core processes such as separation and diversion, coagulation and sedimentation, and significantly improving the overall system treatment stability and efficiency.

[0045] In this embodiment, the separation and diversion unit is used to separate and recover acidic and alkaline washing solutions from the cleaning wastewater. The separation and diversion unit is controlled by a pH sensor and a solenoid valve. When the wastewater pH is ≤5, the acidic washing solution is retained and introduced into the acidic waste liquid storage tank. When the wastewater pH is ≥10, the alkaline washing solution is retained and introduced into the alkaline waste liquid storage tank. The concentration monitoring accuracy of the acid / alkaline washing solution is ±1%, and the start-stop response time of the reuse pump is ≤5s. The precise pH-linked retention, high-precision concentration monitoring, and rapid response design can not only efficiently recover compliant acid / alkaline washing solutions to reduce the cost of reagent re-preparation, but also avoid treatment interference caused by the mixing of acid and alkaline wastewater.

[0046] The multi-stage coagulation and sedimentation unit S10A is used to remove suspended solids, colloidal and complexed pollutants from wastewater. The multi-stage coagulation and sedimentation unit S10A adopts the process of "first-stage coagulation-first-stage sedimentation-second-stage coagulation-second-stage sedimentation", and adds polyaluminum chloride (dosage 10-30mg / L) and polyacrylamide (dosage 0.5-2mg / L) in sequence. The first-stage sedimentation tank is an inclined tube sedimentation tank (inclination angle 60°, surface loading 1.0-1.5m³ / (m²h)) and the second-stage sedimentation tank is a vertical flow sedimentation tank (upward flow velocity 0.5-0.8mm / s). The design of matching parameters between the staged coagulation and the dedicated sedimentation tank can not only initially intercept a large amount of suspended solids through PAC and deeply capture colloidal and complexed pollutants through PAM, but also rely on the high efficiency of inclined tube sedimentation and the stable clarification of vertical flow sedimentation to increase the total pollutant removal rate to more than 85%, thereby reducing the organic load of the subsequent biological treatment unit S105.

[0047] Specifically, the biochemical treatment unit S105 is used to degrade organic pollutants in wastewater. The biochemical treatment unit S105 adopts the "UASB anaerobic reactor + MBBR aerobic process"; the UASB anaerobic reactor has a volumetric loading rate of 2.0-4.0 kg COD / (m³d) and a reaction temperature of 35-38℃, with a COD removal rate of ≥70%; the MBBR aerobic process is filled with 30%-50% polyethylene suspended biological carrier, and the dissolved oxygen is controlled at 2-4 mg / L, with a further COD removal rate of ≥85%. The staged synergistic design of anaerobic degradation of high-concentration COD and aerobic deep purification, combined with the adaptability of the high volumetric loading of UASB and the enhancement effect of MBBR biological carrier, can achieve a total COD removal rate of over 90%.

[0048] In this embodiment, the advanced treatment unit S106 is used to purify wastewater to the standard for metal product cleaning and reuse. The advanced treatment unit S106 adopts the process of "ozone (O3)-ultraviolet (UV) advanced oxidation + ultrafiltration + reverse osmosis". The O3 dosage is 10-20 mg / L, the UV wavelength is 254 nm, the light intensity is 80-120 mW / cm², and the mineralization rate of recalcitrant organic matter is ≥60%. The ultrafiltration adopts PVDF hollow fiber membrane (molecular weight cutoff 10000-30000 Da). The reverse osmosis adopts low-pressure reverse osmosis membrane, and the operating pressure is 1.0-1.5 MPa. The desalination rate is ≥98%, and the resistivity of the product water is ≥10 MΩcm. The multi-process synergy efficiently mineralizes recalcitrant organic matter, retains impurities and desalinates, and the product water meets the standard for fine washing and reuse, ensuring the stable and reliable quality of the reused water.

[0049] The recycled water storage and distribution unit S107 is used to store clean water and return it. The recycled water storage and distribution unit S107 includes a sterile clean water tank and an intelligent distribution module. The sterile clean water tank has a built-in ultraviolet disinfection device, and the total number of bacteria in the recycled water is ≤100 CFU / mL. The intelligent distribution module is linked with a flow meter and a solenoid valve. It can distribute recycled water according to the real-time water demand of the rough washing, fine washing and other processes in the metal product cleaning process S101. The flow distribution accuracy is ≤5%. Ultraviolet disinfection ensures the sterility and safety of the recycled water. The intelligent and accurate distribution is adapted to the needs of different cleaning processes, and effectively improves the utilization rate of recycled water and the adaptability of processes.

[0050] Specifically, the multi-stage coagulation and sedimentation unit S10A is also equipped with a sludge treatment unit S201 and a resource utilization module. The sludge treatment unit S201 is connected to the resource utilization module. The sludge treatment unit S201 is used to treat the sludge generated by the multi-stage coagulation and sedimentation unit S10A. The resource utilization module S202 is used to convert the sludge treatment products into resources. The sludge treatment and resource utilization are linked to achieve sludge reduction and conversion into usable resources at the same time, reducing solid waste disposal costs, reducing secondary pollution, and improving the environmental benefits of the system. The sludge thickening module adopts a centrifugal thickener with a speed of 3000-5000 r / min, which can concentrate the sludge moisture content from 99% to ≤95%.

[0051] In this embodiment, the sludge dewatering module adopts a belt filter press, and the moisture content of the sludge cake is ≤60%. The resource utilization module S202 can mix dewatered sludge with clay and slag at a mass ratio of 3:5:2, granulate it, and then calcine it at 800-1000℃ for 2-3 hours to produce ceramsite with a bulk density of 600-800kg / m³. The ceramsite is used as water treatment filter media or building filler. Centrifugal concentration and belt filter press effectively reduce the moisture content of sludge. Calcining to produce ceramsite realizes resource utilization, which reduces the cost of solid waste disposal and creates practical value. The intelligent control and regulation unit S108 is used to monitor the operating parameters of each unit in real time and automatically adjust the process parameters.

[0052] The metal product cleaning process S101 is connected to the cleaning wastewater transmission unit S102, the cleaning wastewater transmission unit S102 is connected to the pretreatment unit S103, the pretreatment unit S103 is connected to the separation and diversion unit, the separation and diversion unit is connected to the multi-stage coagulation and sedimentation unit S10A, the outlet of the multi-stage coagulation and sedimentation unit S10A is connected to the biochemical treatment unit S105, the biochemical treatment unit S105 is connected to the deep treatment unit S106, the deep treatment unit S106 is connected to the recycled water storage and distribution unit S107, and the recycled water storage and distribution unit S107 returns the recycled water to the metal product cleaning process S101.

[0053] Specifically, the intelligent control and regulation unit S108 is communicatively connected to the metal product cleaning process S101, the cleaning wastewater transmission unit S102, the pretreatment unit S103, the quality and flow separation unit, the multi-stage coagulation and sedimentation unit S10A, the biochemical treatment unit S105, the deep treatment unit S106, and the recycled water storage and distribution unit S107.

[0054] The workflow of the above embodiments is as follows:

[0055] This wastewater recycling and treatment system for cleaning metal products is in use;

[0056] Step 1: The metal product cleaning process S101 is run to clean the metal. The generated metal product cleaning wastewater is collected by the cleaning wastewater transmission unit S102 and transmitted to the pretreatment unit S103.

[0057] Step 2: The pretreatment unit S103 starts the water quality adjustment device to adjust the pH of the wastewater to 6-9 and the temperature adjustment device to adjust the temperature to 25-35℃. Then, the oil is removed by the air flotation oil removal component (adsorption rate ≥95%). Finally, the fine filter component retains large particulate impurities such as metal debris and fibers of 5μm and above, completing the preliminary purification.

[0058] Step 3: The pretreated wastewater enters the separation and diversion unit. This unit is linked to a solenoid valve via a pH sensor. When the wastewater pH is ≤5, the acidic washing solution is retained and introduced into the acidic waste liquid storage tank; when the pH is ≥10, the alkaline washing solution is retained and introduced into the alkaline waste liquid storage tank (the monitoring accuracy of acid / alkali washing solution concentration is ±1%, and the start-stop response time of the reuse pump is ≤5s), thus realizing the separation and recycling of acid and alkali washing solutions.

[0059] Step 4: After separation and diversion, the wastewater enters the multi-stage coagulation and sedimentation unit S10A. First, 10-30 mg / L polyaluminum chloride (PAC) is added to the primary coagulation tank and stirred at 80-120 r / min. Then, it enters the primary sedimentation tank with an inclined tube angle of 60° and a surface loading of 1.0-1.5 m³ / (m²・h). Subsequently, 0.5-2 mg / L polyacrylamide (PAM) is added to the secondary coagulation tank and stirred at 40-60 r / min. Then, it enters the vertical flow secondary sedimentation tank with an upward flow velocity of 0.5-0.8 mm / s to gradually remove suspended solids, colloidal and complexed pollutants.

[0060] Step 5: The effluent from the multi-stage coagulation and sedimentation unit S10A enters the biological treatment unit S105. First, it passes through a UASB anaerobic reactor (volume loading 2.0-4.0 kg COD / (m³・d), reaction temperature 35-38℃) to efficiently degrade high-concentration organic pollutants (COD removal rate ≥70%). Then, it enters the MBBR aerobic process section filled with 30%-50% polyethylene suspended biological carrier, with dissolved oxygen controlled at 2-4 mg / L, to further degrade low-concentration residual organic matter (COD removal rate ≥85%), thus completing the degradation of organic pollutants.

[0061] Step 6: The wastewater after biochemical treatment enters the advanced treatment unit S106, where it first undergoes an advanced oxidation process of "ozone (O3 dosage 10-20 mg / L) - ultraviolet light (wavelength 254 nm, light intensity 80-120 mW / cm²)" to mineralize recalcitrant organic matter (mineralization rate ≥60%). Then, it passes through a PVDF hollow fiber ultrafiltration membrane with a molecular weight cutoff of 10000-30000 Da to retain colloids and bacteria. Finally, it is treated by a low-pressure reverse osmosis membrane with an operating pressure of 1.0-1.5 MPa and a desalination rate of ≥98%, so that the resistivity of the product water is ≥10 MΩ・cm, meeting the standard for fine washing and reuse of metal products.

[0062] Step 7: The deep-treated clean water enters the recycled water storage and distribution unit S107. The built-in ultraviolet disinfection device in the sterile clean water tank controls the total number of bacteria in the recycled water to ≤100CFU / mL. The intelligent distribution module is linked with the flow meter and the solenoid valve to send the recycled water back to the metal product cleaning process S101 according to the real-time water demand of the rough washing, fine washing and other processes in the metal product cleaning process S101 (flow distribution accuracy ≤5%).

[0063] Step 8: The sludge produced by the multi-stage coagulation and sedimentation unit S10A enters the sludge treatment unit S201. First, it is concentrated from 99% to ≤95% by a centrifugal thickener with a speed of 3000-5000 r / min. Then, it is dewatered by a belt filter press until the moisture content of the sludge cake is ≤60%. The dewatered sludge enters the resource utilization module S202, where it is mixed with clay and slag at a mass ratio of 3:5:2. After granulation, it is calcined at 800-1000℃ for 2-3 hours to produce ceramsite with a bulk density of 600-800 kg / m³ (used as water treatment filter media or building filler).

[0064] Step 9: The intelligent control and regulation unit S108 uses a multi-parameter sensor group (detecting pH, COD, flow rate, liquid level, and turbidity at a frequency of 1 time / minute, with a detection accuracy of ±2% of the measured value) to monitor in real time the operating parameters of the metal product cleaning process S101, the cleaning wastewater transmission unit S102, the pretreatment unit S103, the fractional flow unit, the multi-stage coagulation and sedimentation unit S10A, the biochemical treatment unit S105, the deep treatment unit S106, and the recycled water storage and distribution unit S107. It also has a built-in fuzzy PID control algorithm to automatically adjust the process parameters of each unit, such as the dosage of reagents, stirring speed, aeration intensity, and membrane module flux. At the same time, it supports remote viewing, parameter setting, and fault early warning (fault early warning response time ≤ 1 minute) through 4G / 5G network, realizing intelligent closed-loop control of the entire system.

[0065] All electrical components mentioned in the text are electrically connected to the main controller and power supply. The main controller can be a conventional and known device such as a computer, and the existing publicly available power connection technology will not be elaborated in the text.

[0066] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wastewater recycling and treatment system for cleaning metal products, characterized in that: It includes a metal product cleaning process, a cleaning wastewater transmission unit, a pretreatment unit, a branch diversion unit, a multi-stage coagulation and sedimentation unit, a biochemical treatment unit, a deep treatment unit, a recycled water storage and distribution unit, and an intelligent control and regulation unit; The metal product cleaning process is used to clean metal and generate metal product cleaning wastewater. The wastewater transmission unit is used to collect and transmit the wastewater generated in the metal product cleaning process. The pretreatment unit is used to adjust the water quality, remove oil and filter large particulate impurities in the wastewater from cleaning metal products. The separation and diversion unit is used to separate and recover acidic and alkaline washing solutions from the cleaning wastewater. The multi-stage coagulation and sedimentation unit is used to remove suspended solids, colloidal and complexed pollutants from wastewater. The biochemical treatment unit is used to degrade organic pollutants in wastewater; The advanced treatment unit is used to purify wastewater to the standard for cleaning and reuse of metal products. The recycled water storage and distribution unit is used to store clean water and return it; The intelligent control and regulation unit is used to monitor the operating parameters of each unit in real time and automatically adjust the process parameters. The metal product cleaning process is connected to the cleaning wastewater transmission unit, the cleaning wastewater transmission unit is connected to the pretreatment unit, the pretreatment unit is connected to the separation and diversion unit, the separation and diversion unit is connected to the multi-stage coagulation and sedimentation unit, the effluent end of the multi-stage coagulation and sedimentation unit is connected to the biochemical treatment unit, the biochemical treatment unit is connected to the deep treatment unit, the deep treatment unit is connected to the recycled water storage and distribution unit, and the recycled water storage and distribution unit returns the recycled water to the metal product cleaning process. The intelligent control and regulation unit is communicatively connected to the metal product cleaning process, the cleaning wastewater transmission unit, the pretreatment unit, the quality and flow separation unit, the multi-stage coagulation and sedimentation unit, the biochemical treatment unit, the deep treatment unit, and the recycled water storage and distribution unit.

2. The wastewater recycling and treatment system for cleaning metal products according to claim 1, characterized in that: The metal product cleaning process includes at least one metal product cleaning tank, which is equipped with a spray assembly for spraying cleaning liquid. After the cleaning liquid comes into contact with the metal product, it forms the metal product cleaning wastewater.

3. The wastewater recycling and treatment system for cleaning metal products according to claim 2, characterized in that: The pretreatment unit integrates a pH adjustment device, a temperature adjustment device, an air flotation oil removal component, and a precision filtration component. The pH adjustment device can adjust the pH of the wastewater to 6-9, the temperature adjustment device can adjust the temperature of the wastewater to 25-35℃, the air flotation oil removal component has an oil adsorption rate of ≥95%, and the precision filtration component can retain metal debris and fiber impurities of 5μm and above.

4. The wastewater recycling and treatment system for cleaning metal products according to claim 3, characterized in that: The separation and diversion unit is controlled by a pH sensor and a solenoid valve. When the wastewater pH is ≤5, the acidic washing solution is retained and introduced into the acidic waste liquid storage tank. When the wastewater pH is ≥10, the alkaline washing solution is retained and introduced into the alkaline waste liquid storage tank. The monitoring accuracy of the acid / alkali washing solution concentration is ±1%, and the start-stop response time of the reuse pump is ≤5s.

5. The wastewater recycling and treatment system for cleaning metal products according to claim 4, characterized in that: The multi-stage coagulation and sedimentation unit adopts a "first-stage coagulation-first-stage sedimentation-second-stage coagulation-second-stage sedimentation" process, in which polyaluminum chloride (dosage 10-30 mg / L) and polyacrylamide (dosage 0.5-2 mg / L) are added sequentially; the first-stage sedimentation tank is an inclined tube sedimentation tank (inclination angle 60°, surface loading 1.0-1.5 m³ / (m²h)), and the second-stage sedimentation tank is a vertical flow sedimentation tank (upward flow velocity 0.5-0.8 mm / s).

6. The wastewater recycling and treatment system for cleaning metal products according to claim 5, characterized in that: The biochemical treatment unit adopts a "UASB anaerobic reactor + MBBR aerobic process"; the UASB anaerobic reactor has a volumetric loading rate of 2.0-4.0 kg COD / (m³d) and a reaction temperature of 35-38℃, with a COD removal rate of ≥70%; the MBBR aerobic process is filled with 30%-50% polyethylene suspended biological carrier, and the dissolved oxygen is controlled at 2-4 mg / L, with a further COD removal rate of ≥85%.

7. The wastewater recycling and treatment system for cleaning metal products according to claim 6, characterized in that: The advanced treatment unit adopts the "ozone (O3)-ultraviolet (UV) advanced oxidation + ultrafiltration + reverse osmosis" process; the O3 dosage is 10-20 mg / L, the UV wavelength is 254 nm, the light intensity is 80-120 mW / cm², and the mineralization rate of recalcitrant organic matter is ≥60%; the ultrafiltration uses PVDF hollow fiber membrane (molecular weight cutoff 10000-30000 Da); the reverse osmosis uses low-pressure reverse osmosis membrane, and the operating pressure is 1.0-1.5 MPa, the desalination rate is ≥98%, and the resistivity of the product water is ≥10 MΩcm.

8. A wastewater recycling and treatment system for cleaning metal products according to claim 7, characterized in that: The recycled water storage and distribution unit includes a sterile clean water tank and an intelligent distribution module; the sterile clean water tank has a built-in ultraviolet disinfection device, and the total number of bacteria in the recycled water is ≤100 CFU / mL; the intelligent distribution module is linked with a flow meter and a solenoid valve, and can distribute recycled water according to the real-time water demand of the rough washing, fine washing and other processes in the metal product cleaning process, with a flow distribution accuracy of ≤5%.

9. A wastewater recycling and treatment system for cleaning metal products according to claim 1, characterized in that: The multi-stage coagulation and sedimentation unit is also equipped with a sludge treatment unit and a resource utilization module; the sludge treatment unit is connected to the resource utilization module, the sludge treatment unit is used to treat the sludge produced by the multi-stage coagulation and sedimentation unit, and the resource utilization module is used to perform resource conversion on the sludge treatment products.

10. A wastewater recycling and treatment system for cleaning metal products according to claim 9, characterized in that: The sludge treatment unit includes a sludge thickening module and a sludge dewatering module. The sludge thickening module uses a centrifugal thickener with a rotation speed of 3000-5000 r / min, concentrating the sludge moisture content from 99% to ≤95%. The sludge dewatering module uses a belt filter press with a cake moisture content ≤60%. The resource utilization module can mix dewatered sludge with clay and slag at a mass ratio of 3:5:2, granulate the mixture, and then calcine it at 800-1000℃ for 2-3 hours to produce ceramsite with a bulk density of 600-800 kg / m³. The ceramsite is used as water treatment filter media or building filler.

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