Heavy metal sewage deep purification system integrating membrane separation and chemical precipitation

Abstract

The invention discloses a heavy metal sewage deep purification system integrating membrane separation and chemical precipitation, and relates to the technical field of sewage treatment.The system comprises a sewage primary treatment module, a water quality parameter acquisition module, a process parameter decision module, a precipitation reaction regulation and control module and a deep separation and purification module; through a combined structure of coarse and fine grids and a horizontal flow sedimentation tank in the sewage primary treatment module, large-particle impurities and suspended solids in sewage are removed, a stable water quality basis is provided for subsequent treatment, the water quality parameter acquisition module acquires parameter data in real time through a multi-sensor fusion array, and the water quality parameter acquisition module acquires the water quality parameter data in real time. Accurate data support is provided for technological parameter decision making, the technological parameter decision making module generates a control instruction of precipitant adding and membrane operation pressure through calculation based on real-time data and historical operation data, the accuracy and adaptability of the treatment process are ensured, and the accurate control strategy not only improves the removal efficiency of heavy metal ions, but also improves the removal efficiency of the membrane operation pressure. And the risk of membrane pollution is also reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a heavy metal sewage deep purification system integrating membrane separation and chemical precipitation. BACKGROUND

[0002] With the rapid development of industrialization, heavy metal pollution problems are becoming increasingly serious, especially heavy metal wastewater discharge poses a serious threat to the ecological environment and human health. Heavy metal ions have characteristics such as high toxicity, non-degradability, and easy accumulation. Once they enter the water body, they not only destroy the ecological balance, but also can enter the human body through the food chain and cause various diseases. Therefore, how to efficiently and economically treat heavy metal wastewater and achieve sustainable utilization of water resources has become a key problem to be solved in the current environmental protection field.

[0003] However, traditional heavy metal wastewater treatment technologies mainly use single technology to purify heavy metal wastewater, such as chemical precipitation method and membrane separation technology. Although the chemical precipitation method can effectively remove heavy metal ions in wastewater, the dosage of the precipitant often depends on experience and is difficult to accurately control according to real-time water quality conditions, resulting in unstable precipitation effect and easy generation of excess precipitant residues, causing secondary pollution. At the same time, the flocs generated by the chemical precipitation method often have large volume and density, which can easily block the pipeline or membrane assembly in the subsequent treatment process, increasing the maintenance cost. Although the membrane separation technology can achieve efficient interception of heavy metal ions, membrane pollution has always been the main factor restricting its wide application. Membrane pollution not only leads to a decrease in membrane flux and treatment efficiency, but also increases the frequency of membrane cleaning and replacement, thereby increasing the operation cost. In addition, traditional technologies often lack real-time monitoring and dynamic adjustment capabilities for water quality parameters, making it difficult to adapt to changes in different water quality conditions and treatment requirements, limiting the further improvement of their treatment effect. SUMMARY

[0004] The present application aims to make up for the shortcomings of the prior art and provides a heavy metal sewage deep purification system integrating membrane separation and chemical precipitation. The combination of coarse and fine grids and horizontal flow sedimentation tanks in the sewage pretreatment module removes large particle impurities and suspended solids in the sewage, providing a stable water quality basis for subsequent treatment. The water quality parameter acquisition module acquires real-time parameter data through a multi-sensor fusion array, providing accurate data support for process parameter decision-making. The process parameter decision-making module generates control instructions for precipitant dosage and membrane operating pressure based on real-time data and historical operation data, ensuring the accuracy and adaptability of the treatment process. This precise control strategy not only improves the removal efficiency of heavy metal ions, but also reduces the risk of membrane pollution, thereby improving the overall treatment quality.

[0005] The application provides a heavy metal wastewater deep purification system integrating membrane separation and chemical precipitation. The wastewater preliminary treatment module introduces the heavy metal wastewater to be treated through a water inlet pipeline, performs combined treatment on the wastewater through a combined treatment structure, removes large-particle impurities, and outputs pretreated water with stable water quality. The water quality parameter acquisition module acquires the pH, heavy metal ion concentration, turbidity, suspended matter content and Zeta potential of the pretreated water in real time when the pretreated water flows through the connecting pipeline, and pre-processes the acquired parameter data. The process parameter decision module generates a control instruction of the precipitant dosage and the membrane operation pressure based on the pre-processed parameter data and historical operation data, through a process coordination degree formula, a composite precipitant dosage dynamic calculation formula and a membrane separation operation pressure self-adaptive adjustment formula. The precipitation reaction regulation module generates flocculation with low membrane pollution tendency and outputs low-load effluent by adjusting the precipitant dosage and the dosage rate according to the precipitant dosage control instruction when the pretreated water flows into the reaction kettle with the built-in stirring assembly. The deep separation and purification module adjusts the operation pressure according to the result of the membrane separation operation pressure self-adaptive adjustment formula and the pressure monitoring data, and realizes deep purification of the wastewater.

[0006] Further, the combined treatment structure in the wastewater preliminary treatment module is composed of a coarse grid, a fine grid and a horizontal flow sedimentation tank, wherein the grid spacing of the coarse grid is 10-20 mm, the grid spacing of the fine grid is 1-3 mm, and the two-stage grids are both equipped with an automatic pollution removal unit.

[0007] Further, the multi-sensor fusion array in the water quality parameter acquisition module is a pH sensor, a heavy metal ion concentration sensor, a turbidity sensor, a suspended matter content sensor and a Zeta potential sensor, wherein the pH sensor acquires the pH value, the heavy metal ion concentration sensor acquires the heavy metal ion concentration, the turbidity sensor acquires the turbidity, the suspended matter content sensor acquires the suspended matter content, and the Zeta potential sensor acquires the Zeta potential.

[0008] Further, in the process parameter decision module, the process synergy adaptation degree is calculated based on the pre-processed parameter data and historical operation data through a process synergy adaptation degree formula, and the process synergy adaptation degree calculation formula is: wherein, is the process synergy adaptation degree, is the parameter weight, and , is the reference pH value of the precipitation reaction, is the reference value of the heavy metal concentration under typical working conditions, is the critical absolute value of Zeta potential for stable generation of flocs, is the reference value of suspended solids, is the reference value of turbidity, is the collected pH, heavy metal ion concentration, Zeta potential, suspended solids content and turbidity of the pre-processed water body, respectively.

[0009] Further, in the process parameter decision module, the real-time dosage of the composite precipitator is calculated through a composite precipitator dosage dynamic calculation formula, and a precipitator dosage control instruction is generated based on the real-time dosage of the composite precipitator, and the composite precipitator dosage dynamic calculation formula is: wherein, is the real-time dosage of the composite precipitator, is the heavy metal precipitation reaction metering coefficient, is the turbidity correction coefficient, and , is the reference threshold value of turbidity, is the process synergy adaptation degree, , is the collected heavy metal ion concentration and turbidity of the pre-processed water body, respectively.

[0010] Further, in the process parameter decision module, the real-time operating pressure of the membrane module is calculated through a membrane separation operating pressure self-adaptive adjustment calculation formula, and a membrane operating pressure control instruction is generated based on the real-time operating pressure of the membrane module, and the membrane separation operating pressure self-adaptive adjustment calculation formula is: wherein, is the real-time operating pressure of the membrane module, is the suspended solids-pressure correlation coefficient, is the Zeta potential influence coefficient, and , is the critical absolute value of Zeta potential for stable generation of flocs, is the process synergy adaptation degree, is the minimum effective operating pressure of the membrane module, , is the collected suspended solids content and Zeta potential of the pre-processed water body, respectively.

[0011] Furthermore, in the precipitation reaction control module, the reaction vessel volume is 5-50 m³. 3 The built-in stirring component of the vessel is a double-layer paddle agitator with a stirring speed adjustable within the range of 50-200 r / min. The metering and dosing component adjusts the dosage and dosing rate of the composite precipitant based on the precipitant dosing control command. The composite precipitant is a mixture of inorganic precipitant and organic coagulant aid. The stirring component stirs at a rate of 120-200 r / min for 0-15 min after the agent is added to ensure that the precipitant and wastewater are fully mixed. From 15 min after the agent is added until the floc settling is completed, the stirring rate is 80-120 r / min to promote floc aggregation and growth. After the floc settling is completed, low-film fouling-prone flocs with a particle size of 50-200 μm are generated. Heavy metal ions are removed by precipitation through chemical reaction to form precipitates that are encapsulated inside the flocs.

[0012] Furthermore, in the deep separation and purification module, the membrane separation unit has a built-in membrane module and is equipped with a pressure monitoring unit and an adaptive adjustment unit. The membrane module is a hollow fiber ultrafiltration membrane, nanofiltration membrane, or reverse osmosis membrane module. The pressure monitoring unit monitors the inlet and outlet pressure difference of the membrane module in real time. The adaptive adjustment unit adjusts the membrane separation operating pressure based on the membrane operating pressure control command and the real-time monitoring data of the pressure monitoring unit by adjusting the frequency of the feed pump. When the pollutant content in the precipitated water is low, the operating pressure is reduced; when the pollutant content is high, the operating pressure is increased. Through membrane separation, residual heavy metal ions, trace suspended solids, and other pollutants in the wastewater are intercepted, ultimately achieving deep purification of the wastewater.

[0013] Compared with existing technologies, this integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater has the following advantages: I. This invention removes large particulate impurities and suspended solids from wastewater through a combination of coarse and fine screens and a horizontal flow sedimentation tank in the wastewater pretreatment module, providing a stable water quality foundation for subsequent treatment. The water quality parameter acquisition module collects various parameter data in real time through a multi-sensor fusion array, providing accurate data support for process parameter decisions. Based on real-time data and historical operating data, the process parameter decision module calculates and generates control commands for precipitant dosing and membrane operating pressure, ensuring the accuracy and adaptability of the treatment process. This precise control strategy not only improves the removal efficiency of heavy metal ions but also reduces the risk of membrane fouling, thereby improving the overall treatment quality.

[0014] Second, this invention achieves dynamic adjustment of the membrane separation operating pressure by using a pressure monitoring unit equipped in the membrane separation unit of the deep separation and purification module to capture the pressure difference between the inlet and outlet of the membrane module in real time, combined with the precise control of the feed pump frequency by the adaptive adjustment unit. This adaptive adjustment mechanism ensures that the operating state can be automatically optimized for different water quality conditions and treatment needs, which not only ensures the stability and efficiency of the treatment effect, but also effectively avoids membrane fouling or low treatment efficiency caused by improper pressure.

[0015] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 A flowchart of a deep purification system for heavy metal wastewater that integrates membrane separation and chemical precipitation; Figure 2 This is a framework diagram of a deep purification system for heavy metal wastewater that integrates membrane separation and chemical precipitation. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] Example 1: In the context of heavy metal purification of underground water in non-ferrous metal mines, the water flowing into these mines during mining operations carries a large amount of rock debris, unmined mineral powder particles, and silt and other impurities brought in from the surface. This wastewater not only contains various heavy metal ions such as copper, lead, and zinc, but also exhibits extremely high turbidity due to the presence of solid impurities. The wastewater is introduced into a combined treatment structure via a dedicated inlet pipe. This structure consists of a coarse screen, a fine screen, and a horizontal flow sedimentation tank. The wastewater first flows through the coarse screen with a spacing of 10-20mm, intercepting large impurities such as visible rock debris and hard slag, preventing subsequent pipe blockage. It then flows through the fine screen with a spacing of 1-3mm, further trapping fine mineral powder particles and silt, preventing further contamination. To prevent these tiny impurities from affecting the subsequent sedimentation reaction, both stages of the screen are equipped with automatic cleaning units that periodically activate to mechanically scrape away impurities adhering to the screens and collect them in a dedicated collection box, ensuring the screens maintain unobstructed water flow. The pre-treated wastewater then enters a horizontal flow sedimentation tank. This tank has an effective water depth of 2.0-3.0m and a hydraulic retention time of 1.5-2.5 hours. During the slow flow of the wastewater, gravity causes the remaining larger solid particles to naturally settle to the bottom. A conical sludge hopper at the bottom of the sedimentation tank, with an inclination angle of 60-70°, collects this settled sludge, which is then periodically discharged by a sludge pump. The final output is pre-treated water with minimal quality fluctuations and a significantly reduced solid impurity content. Figure 1 As shown, this lays a stable foundation for the subsequent precise treatment of heavy metal ions.

[0020] After the pretreated water flows out of the horizontal flow sedimentation tank, it flows to the subsequent stages through a closed connecting pipeline. In the middle of the connecting pipeline, a multi-sensor fusion array consisting of a pH sensor, a heavy metal ion concentration sensor, a turbidity sensor, a suspended solids content sensor, and a Zeta potential sensor is arranged. This array can capture changes in key water parameters in real time. The pH sensor continuously monitors the pH value of the water, the heavy metal ion concentration sensor accurately captures the real-time content of target heavy metals such as copper, lead, and zinc, the turbidity sensor monitors the content of remaining small impurities in the water, the suspended solids content sensor further collects the concentration of fine particles that have not settled in the water, and the Zeta potential sensor monitors the charged state of particles in the water. The collected raw data is preprocessed, including removing instantaneous abnormal data caused by water flow impact and correcting deviations caused by sensor zero-point drift, to ensure that each set of parameter data can accurately reflect the current water quality status of the pretreated water.

[0021] Based on the pre-processed parameter data and combined with the historical operational data of underground water inflow in the mine over the past year—which includes the water quality characteristics and corresponding final treatment parameters of water inflow at different seasons and mining depths—this data provides a reference for decision-making under current operating conditions. First, the current water quality parameters are matched with the historical optimal parameters using a process synergy compatibility formula to determine the degree of compatibility between the sedimentation reaction and membrane separation processes under current operating conditions. The formula for calculating the process synergy compatibility is as follows: ,in, For process compatibility and adaptability, For parameter weights, and , The pH value is the reference value for the precipitation reaction. This is a benchmark value for heavy metal concentration under typical operating conditions. The absolute value of the critical Zeta potential for stable floc formation. As the baseline value for suspended solids, The turbidity reference value, The pretreated water samples were collected for pH, heavy metal ion concentration, Zeta potential, suspended solids content, and turbidity. Based on process synergy and compatibility, a dynamic calculation formula for the dosage of the composite precipitant was used. Combined with the current heavy metal ion concentration and turbidity in the water, the real-time dosage of the composite precipitant that allows for sufficient reaction of heavy metal ions without wasting reagents was determined. The dynamic calculation formula for the dosage of the composite precipitant is as follows: ,in, This refers to the real-time dosage of the composite precipitant. This represents the stoichiometric coefficient for heavy metal precipitation reactions. This is the turbidity correction factor, and , The turbidity reference threshold, For process compatibility and adaptability, , These represent the concentration of heavy metal ions and turbidity of the pretreated water, respectively. Simultaneously, based on the suspended solids content and Zeta potential data, an adaptive adjustment formula for membrane separation operating pressure is used to calculate the real-time operating pressure that ensures effective membrane separation while preventing excessive fouling of the membrane module. The adaptive adjustment formula for membrane separation operating pressure is as follows: ,in, For the real-time operating pressure of the membrane module, The suspended matter-pressure correlation coefficient. Let be the influence coefficient of the Zeta potential, and , The absolute value of the critical Zeta potential for stable floc formation. For process compatibility and adaptability, The minimum effective operating pressure for the membrane module, , They are respectively the content of suspended solids and the Zeta potential of the pretreated water collected. Finally, based on the calculation results, clear control instructions for the dosing of the precipitant and the control instructions for the membrane operating pressure are generated.

[0022] The pretreated water flows into a reaction kettle with a volume of 5 - 50 m 3 and equipped with a stirring component. The stirring component is a double-layer paddle stirrer, and the overall stirring rate can be adjusted within the range of 50 - 200 r / min. Based on the control instructions for the dosing of the precipitant, the metering dosing component supporting the kettle body is controlled to start, and a composite precipitant composed of an inorganic precipitant and an organic coagulant aid is added into the reaction kettle. The inorganic precipitant is mainly used to chemically react with heavy metal ions in the water to form insoluble precipitates, and the organic coagulant aid assists these precipitates to form larger and more stable flocs; within 0 - 15 minutes after the dosing of the agent, the stirrer operates at a rate of 120 - 200 r / min to ensure that the composite precipitant can be fully mixed with the water in a short time, enabling the agent molecules to fully contact the heavy metal ions and avoiding insufficient local reactions caused by uneven mixing; when 15 minutes have passed since the dosing of the agent, the stirrer automatically adjusts to a rate of 80 - 120 r / min, which can not only prevent the initially formed flocs from being broken by high-speed stirring but also promote the further aggregation and growth of the flocs; after the flocs have completely settled, low-membrane-fouling-tendency flocs with a particle size of 50 - 200 μm are formed in the water. These flocs are not only structurally dense but also can tightly wrap the heavy metal precipitates inside, significantly reducing the treatment load in the subsequent membrane separation process, and finally outputting low-load effluent with a significantly reduced heavy metal ion content.

[0023] The low-load effluent after the precipitation reaction enters the membrane separation unit through a connecting pipeline. The membrane separation unit is equipped with a membrane module, and the membrane module is a hollow fiber ultrafiltration membrane, which is selected according to the water quality characteristics of mine wastewater and has the advantages of strong anti-fouling ability and high interception efficiency; at the same time, it is equipped with a pressure monitoring unit and an adaptive adjustment unit. The sensors of the pressure monitoring unit are respectively installed at the inlet and outlet of the membrane module to continuously monitor the pressure difference at both ends to determine whether there is pollution or blockage in the membrane module; the adaptive adjustment unit, based on the control instructions for the membrane operating pressure and combined with the real-time pressure data fed back by the pressure monitoring unit, changes the membrane separation operating pressure by adjusting the operating frequency of the feed pump. When it is monitored that the content of pollutants in the effluent is low, it means that the interception burden of the membrane is small, and the operating pressure is appropriately reduced to reduce the system energy consumption; when it is monitored that the content of pollutants in the effluent increases, it may be due to a small amount of floc fragmentation resulting in an increase in fine particles, and the operating pressure is promptly increased to ensure that the membrane module can effectively intercept the residual trace heavy metal ions, un-settled small floc fragments and other trace pollutants in the water; through the physical interception of the hollow fiber ultrafiltration membrane, the deep purification of the sewage is finally completed, and it can be directly discharged into the water body around the mine or reused as dust-proof water for the mine underground after further treatment.

[0024] In summary, for underground water inflow in non-ferrous metal mines, impurities are removed through initial treatment using coarse and fine screens and a horizontal flow sedimentation tank; water quality parameters are collected by a multi-sensor fusion array, and after process parameter decisions, a composite precipitant is added to the reactor to generate flocs with low membrane fouling tendency; finally, the water is deeply purified through a hollow fiber ultrafiltration membrane, and the effluent meets the discharge standards.

[0025] Example 2: In the wastewater purification scenario of an automotive parts electroplating workshop, the workshop generates a large amount of wastewater containing heavy metals such as chromium, nickel, and cadmium during production. This wastewater not only contains residual metal salt solutions from the electroplating tanks but also impurities such as decomposition products of electroplating additives and electroplating particles not adhering to the surface of the parts, introduced during the parts cleaning process. Direct discharge would cause serious pollution to the surrounding soil and water sources. The wastewater is collected through the workshop's water collection network and then introduced into a combined treatment structure, consisting of coarse screens, fine screens, and a horizontal flow sedimentation tank. The wastewater first flows through a coarse screen with a spacing of 10-20mm, intercepting large impurities such as fragments of electroplating fixtures, untreated parts scraps, and lumpy electroplating tank residue, preventing these hard objects from damaging subsequent pumps or sensors. Next, it flows through a fine screen with a spacing of 1-3mm, trapping tiny electroplating particles in the water. Tiny impurities such as coating detachment particles and additive residues are removed to prevent them from adsorbing heavy metal ions and affecting the efficiency of subsequent precipitation reactions. The automatic cleaning unit of the two-stage screen automatically starts according to the water level difference before and after the screen. When the water level difference exceeds the set threshold, the cleaning device cleans the impurities on the screen by high-pressure water flushing combined with mechanical scraping to ensure stable water flow. The wastewater treated by the screen then enters a horizontal flow sedimentation tank. The effective water depth of the sedimentation tank is 2.0-3.0m and the hydraulic retention time is 1.5-2.5 hours. During the slow flow of the wastewater in the tank, the denser solid impurities in the water will gradually settle to the bottom of the tank. The conical sludge hopper at the bottom of the sedimentation tank with an inclination angle of 60-70° collects and stores this sludge containing heavy metals, and then discharges it through a screw pump. Finally, the output is pre-treated water with stable water quality and no obvious solid impurities, which prepares for the subsequent precise removal of heavy metal ions.

[0026] After the pretreated water flows out of the horizontal flow sedimentation tank, it flows to the subsequent stages through an insulated connecting pipeline to prevent changes in ambient temperature from affecting the pH value and heavy metal ion activity. Near the sedimentation reaction control stage, a multi-sensor fusion array consisting of a pH sensor, a heavy metal ion concentration sensor, a turbidity sensor, a suspended solids content sensor, and a Zeta potential sensor is arranged along the pipeline. The pH sensor is specifically designed for acidic or alkaline environments of electroplating wastewater, accurately monitoring the water's pH value; the heavy metal ion concentration sensor can specifically identify the concentration of target heavy metals such as chromium, nickel, and cadmium; the turbidity sensor detects the content of remaining minute impurities in the water in real time; the suspended solids content sensor further collects the concentration of non-sedimented fine particles in the water; and the Zeta potential sensor monitors the charge status of particles in the water. The collected raw data is preprocessed to ensure a consistent data format for different types of parameters.

[0027] Based on the pretreated parameter data and combined with the historical operating data of the automotive parts electroplating workshop's wastewater treatment over the past six months—data including differences in wastewater quality from different electroplating processes and optimization results of treatment parameters under different production loads—current decisions can be more aligned with actual production conditions. Firstly, using the process synergy fit formula, the optimal fit value for the current precipitation reaction and membrane separation processes is calculated by comprehensively considering the matching degree between current water parameters such as pH, heavy metal concentration, and Zeta potential and historical final treatment conditions. The formula for calculating the process synergy fit is as follows: Based on process synergy and compatibility, and using the dynamic calculation formula for the dosage of the composite precipitant, combined with the current concentration and turbidity of specific heavy metals in the water, the real-time dosage of the composite precipitant is determined to ensure that heavy metal ions react completely to form precipitates without causing secondary pollution of the water due to excessive dosage. The dynamic calculation formula for the dosage of the composite precipitant is as follows: Simultaneously, based on the suspended solids content and Zeta potential data in the water, and using the adaptive adjustment formula for membrane separation operating pressure, a real-time operating pressure that balances membrane separation efficiency and membrane lifespan is calculated. The adaptive adjustment formula for membrane separation operating pressure is as follows: Finally, based on the calculation results, precipitant dosing control commands and membrane operating pressure control commands are generated, such as... Figure 2 As shown.

[0028] Pretreated water flows into a 5-50m³ volume via pipeline. 3Furthermore, the reactor with a built-in stirring assembly uses a double-layer paddle stirrer, and the stirring speed can be flexibly adjusted within the range of 50-200 r / min. Based on the precipitant addition control command, the metering and dosing components of the reactor are activated according to the command requirements to add the composite precipitant into the reactor. Within 0-15 minutes after the reagent is added, the stirrer operates at a speed of 120-200 r / min, allowing the composite precipitant to be fully mixed with the water in a short time, ensuring that every heavy metal ion is fully mixed. Upon contact with the reagent; 15 minutes after the reagent is added, the agitator speed automatically decreases to 80-120 r / min. At this time, fine flocs have initially formed in the water. Low-speed agitation can prevent the flocs from being broken and promote the collision and aggregation of the flocs into low-film-fouling-prone flocs with a particle size of 50-200 μm. After the flocs have completely settled to the bottom of the vessel, the floc sludge containing heavy metals is discharged through the sludge discharge valve at the bottom of the vessel. Finally, low-load effluent with significantly reduced heavy metal ion content and improved water clarity is output.

[0029] Low-load effluent enters the membrane separation unit through an anti-clogging pipeline. The membrane separation unit houses a nanofiltration membrane, specifically selected for the advanced treatment of electroplating wastewater. This membrane effectively removes trace amounts of heavy metal ions and small-molecule organic pollutants. It is equipped with a pressure monitoring unit and an adaptive adjustment unit. The pressure monitoring unit monitors the pressure difference between the inlet and outlet of the membrane module in real time. An increase in the pressure difference indicates the presence of pollutants on the membrane surface, requiring adjustment of the operating pressure to balance the retention effect and the degree of membrane fouling. The adaptive adjustment unit, based on membrane operating pressure control commands and pressure monitoring data, adjusts the inlet and outlet pressures in real time. The frequency of the feed pump is adjusted according to the following conditions: When the effluent heavy metal ion content is low, such as when the chromium ion concentration is close to the discharge standard, the operating pressure is reduced to decrease the operating load on the membrane module and extend the membrane's service life. When the effluent heavy metal ion content is high, it may be due to a small amount of tiny flocs entering the membrane unit. The operating pressure should be increased in time to ensure that the nanofiltration membrane can completely retain the remaining trace heavy metal ions. Through the deep separation effect of the nanofiltration membrane, the wastewater is finally deeply purified. The treated water can be reused in the parts cleaning process of the electroplating workshop, realizing the recycling of water resources and reducing the company's water costs.

[0030] In summary, when treating wastewater from an automotive parts electroplating workshop, the wastewater first undergoes preliminary treatment via coarse and fine screens and a horizontal flow sedimentation tank. A multi-sensor fusion array collects water quality parameters, and after process parameter decisions are made, a composite precipitant is added to the reactor to generate flocs with low membrane fouling tendency. This is then further purified by nanofiltration, and the effluent can be reused for cleaning workshop parts, thus achieving water resource recycling.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A deep purification system for heavy metal wastewater integrating membrane separation and chemical precipitation, characterized in that, The system includes: Wastewater pretreatment module: The wastewater containing heavy metals to be treated is introduced through the inlet pipe, and then treated by the combined treatment structure to remove large particulate impurities and output pretreated water with stable water quality. Water quality parameter acquisition module: When the pretreated water flows through the connecting pipeline, a multi-sensor fusion array is deployed to collect parameter data such as pH, heavy metal ion concentration, turbidity, suspended solids content and Zeta potential of the pretreated water in real time, and preprocess the collected parameter data; Process parameter decision module: Based on the pre-processed parameter data and combined with historical operating data, the module generates control commands for precipitant addition and membrane operating pressure through process synergy compatibility formula, dynamic calculation formula for composite precipitant dosage, and adaptive adjustment formula for membrane separation operating pressure. Sedimentation reaction control module: Pretreated water flows into the reactor with built-in stirring components, and adjusts the amount and rate of flocculant addition according to the flocculant addition control command to generate flocs with low membrane fouling tendency and output low load effluent; Deep separation and purification module: Low-load effluent enters the membrane separation unit through the connecting pipeline. Based on the result of the membrane separation operating pressure adaptive adjustment formula and combined with pressure monitoring data, the operating pressure is adjusted to achieve deep purification of sewage.

2. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 1, characterized in that, The wastewater primary treatment module consists of a combined treatment structure comprising a coarse screen, a fine screen, and a horizontal flow sedimentation tank. The coarse screen has a grid spacing of 10-20 mm to intercept large floating objects and lumpy impurities in the wastewater, while the fine screen has a grid spacing of 1-3 mm to trap small suspended particles. Both screens are equipped with automatic cleaning units. After passing through the screens, the wastewater enters the horizontal flow sedimentation tank, which has an effective water depth of 2.0-3.0 m and a hydraulic retention time of 1.5-2.5 hours. Large solid particles and suspended matter larger than 1 mm in diameter are removed by gravity settling. A conical sludge hopper with an inclination angle of 60-70° is installed at the bottom of the sedimentation tank for centralized collection and discharge of settled sludge.

3. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 1, characterized in that, The water quality parameter acquisition module includes a multi-sensor fusion array consisting of a pH sensor, a heavy metal ion concentration sensor, a turbidity sensor, a suspended solids content sensor, and a Zeta potential sensor. The pH sensor acquires the pH value; the heavy metal ion concentration sensor acquires the heavy metal ion concentration; the turbidity sensor acquires the turbidity; the suspended solids content sensor acquires the suspended solids content; and the Zeta potential sensor acquires the Zeta potential.

4. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 1, characterized in that, In the process parameter decision module, based on the preprocessed parameter data and combined with historical operating data, the process coordination adaptability is calculated using the process coordination adaptability formula, which is as follows: ,in, For process compatibility and adaptability, For parameter weights, and , The pH value is the reference value for the precipitation reaction. This is a benchmark value for heavy metal concentration under typical operating conditions. The absolute value of the critical Zeta potential for stable floc formation. As the baseline value for suspended solids, The turbidity reference value The parameters collected were pH, heavy metal ion concentration, zeta potential, suspended solids content, and turbidity of the pretreated water.

5. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 4, characterized in that, In the process parameter decision module, the real-time dosage of the composite precipitant is calculated using a dynamic calculation formula, and a precipitant dosing control command is generated based on the real-time dosage. The dynamic calculation formula for the composite precipitant dosage is as follows: ,in, This refers to the real-time dosage of the composite precipitant. This represents the stoichiometric coefficient for heavy metal precipitation reactions. This is the turbidity correction factor, and , The turbidity reference threshold, For process compatibility and adaptability, , These represent the concentration of heavy metal ions and turbidity of the pretreated water, respectively.

6. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 4, characterized in that, In the process parameter decision module, the real-time operating pressure of the membrane module is calculated using the adaptive adjustment formula for membrane separation operating pressure, and a membrane operating pressure control command is generated based on the real-time operating pressure of the membrane module. The adaptive adjustment formula for membrane separation operating pressure is as follows: ,in, For the real-time operating pressure of the membrane module, The suspended matter-pressure correlation coefficient. Let be the influence coefficient of the Zeta potential, and , The absolute value of the critical Zeta potential for stable floc formation. For process compatibility and adaptability, The minimum effective operating pressure for the membrane module, , These represent the suspended solids content and Zeta potential of the pretreated water, respectively.

7. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 1, characterized in that, In the precipitation reaction control module, the reactor volume is 5-50m³. 3 The built-in stirring component of the vessel is a double-layer paddle agitator with a stirring speed adjustable within the range of 50-200 r / min. The metering and dosing component adjusts the dosage and dosing rate of the composite precipitant based on the precipitant dosing control command. The composite precipitant is a mixture of inorganic precipitant and organic coagulant aid. The stirring component stirs at a rate of 120-200 r / min for 0-15 min after the agent is added to ensure that the precipitant and wastewater are fully mixed. From 15 min after the agent is added until the floc settling is completed, the stirring rate is 80-120 r / min to promote floc aggregation and growth. After the floc settling is completed, low-film fouling-prone flocs with a particle size of 50-200 μm are generated. Heavy metal ions are removed by precipitation through chemical reaction to form precipitates that are encapsulated inside the flocs.

8. The integrated membrane separation and chemical precipitation system for deep purification of heavy metal wastewater according to claim 1, characterized in that, In the deep separation and purification module, the membrane separation unit has a built-in membrane module and is equipped with a pressure monitoring unit and an adaptive adjustment unit. The membrane module is a hollow fiber ultrafiltration membrane, nanofiltration membrane, or reverse osmosis membrane module. The pressure monitoring unit monitors the inlet and outlet pressure difference of the membrane module in real time. The adaptive adjustment unit adjusts the membrane separation operating pressure based on the membrane operating pressure control command and the real-time monitoring data of the pressure monitoring unit by adjusting the frequency of the feed pump. When the pollutant content in the precipitated water is low, the operating pressure is reduced; when the pollutant content is high, the operating pressure is increased. Through membrane separation, residual heavy metal ions, trace suspended solids, and other pollutants in the wastewater are intercepted, ultimately completing the deep purification of the wastewater.

Images