Equipment for treating heavy metal wastewater

Abstract

The invention discloses equipment for treating heavy metal wastewater, which comprises a reaction tank, a stirring device, a dosing system, an aeration device and a sedimentation tank, a control unit monitors the pH value and the heavy metal concentration in real time, and dynamically adjusts the sodium sulfide dosing amount and the aeration amount: when the pH value is lower than 8.5-9.5, sodium sulfide is added at the speed of 1.5-3 L / min, and when the pH value is higher than 8.5-9.5, an acid neutralizer is added at the speed of 0.5-1.5 L / min; meanwhile, the aeration rate is adjusted to be 2-10 m < 3 > / h according to the heavy metal concentration. When the pH value is stable, the dosing flow is reduced to 0.5-1 L / min, and the aeration rate is reduced to 1-3 m < 3 > / h. The method is used for industrial wastewater treatment, and can improve the heavy metal removal efficiency and reduce the agent consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal wastewater treatment equipment, in particular to equipment for treating heavy metal wastewater. Background Art

[0002] Heavy metal wastewater mainly comes from industries such as electroplating, metallurgy, and chemical industry. The difficulty in its treatment lies in the stable removal of heavy metal ions and the precise control of reaction conditions. Traditional treatment methods usually use chemical precipitation, which precipitates heavy metals into sulfides by adding reagents such as sodium sulfide. However, there are the following problems: First, controlling pH is crucial for sulfide formation, but existing technologies often rely on manual monitoring and adjustment, resulting in inaccurate dosing. Excessively high pH can lead to competition with heavy metal hydroxide precipitation, reducing sulfide precipitation efficiency; while too low a pH can cause hydrogen sulfide gas to escape, causing secondary pollution. Due to large fluctuations in wastewater quality, manual adjustments are difficult to respond to in real time, easily resulting in reagent waste or substandard treatment results.

[0003] Secondly, aeration control is typically fixed or based solely on empirical adjustments, lacking a dynamic correlation with heavy metal concentrations. Insufficient aeration can lead to uneven reactions, resulting in fine sediment particles that are difficult to settle. Excessive aeration can disrupt formed flocs and increase the load on subsequent sedimentation tanks. Existing aeration systems often operate independently, without coordinated optimization with other processes such as dosing and agitation. This results in high energy consumption and limited treatment efficiency.

[0004] Furthermore, conventional equipment's dosing systems often rely on timed or fixed-volume dosing, making it impossible to adjust dosage based on the wastewater's real-time heavy metal concentration. High-concentration wastewater requires higher aeration intensities to promote mixing and oxidation, but existing equipment lacks a coordinated mechanism, making it prone to localized overdosing or inadequate reaction.

[0005] The root cause of these problems lies in the disconnect between monitoring and control, which leads to delayed system response. Developing an integrated system that can monitor water quality parameters in real time and dynamically adjust dosing, aeration, and agitation is key to improving the efficiency of heavy metal wastewater treatment. Summary of the Invention

[0006] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0007] One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of inaccurate pH adjustment leading to reagent waste or low precipitation efficiency in heavy metal wastewater treatment; One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of uneven reaction or excessive energy consumption caused by the mismatch between aeration volume and heavy metal concentration; One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of clogging of sedimentation tanks or sludge loss caused by inaccurate flow control during sludge discharge; One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem that insufficient synergy between stirring and aeration affects the mixing effect; One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of excessive pH fluctuation caused by insufficient initial reaction of dosing; One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of insufficient stirring intensity in high turbidity wastewater leading to suspended sediment; An object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of mismatch between sludge discharge flow and sedimentation height; One object of the present invention is to provide a device for treating heavy metal wastewater, which can solve the problem of sludge entraining clear water due to the rapid drop in liquid level during sludge discharge; One object of the present invention is to provide an apparatus for treating heavy metal wastewater, which can solve the problem of insufficient discharge of sludge from high-concentration heavy metal wastewater; An object of the present invention is to provide a device for treating heavy metal wastewater, which can solve the pipeline impact problem caused by the sudden change of the mud valve opening.

[0008] In order to achieve these objects and other advantages according to the present invention, there is provided an apparatus for treating heavy metal wastewater, comprising a reaction tank, a stirring device disposed in the reaction tank, a dosing system communicated with the reaction tank, an aeration device disposed at the bottom of the reaction tank, and a sedimentation tank connected to a water outlet of the reaction tank; The inner wall of the reaction tank is provided with a pH monitoring probe and a heavy metal concentration monitoring probe, and the pH monitoring probe, the heavy metal concentration monitoring probe, the aeration device and the control unit of the dosing system are electrically connected; The dosing system includes a drug storage tank, a metering pump and a drug dosing pipeline. The drug storage tank stores a sodium sulfide solution with a concentration of 10%-30%; The control unit is used to obtain the pH detection value of the pH monitoring probe in real time and compare the pH detection value with a preset pH threshold range of 8.5-9.5; when the pH detection value is lower than the lower limit of the threshold range, the metering pump is controlled to add sodium sulfide solution at a first flow rate range of 1.5-3 L / min; when the pH detection value is higher than the upper limit of the threshold range, the metering pump is controlled to add an acid neutralizer at a second flow rate range of 0.5-1.5 L / min; The control unit is also used to dynamically adjust the aeration volume according to the heavy metal concentration detection value of the wastewater in the reaction tank. When the heavy metal concentration is 50-100 mg / L, the aeration volume is controlled to be 2-5 m 3 / h; when the heavy metal concentration is 100-200 mg / L, the aeration volume is controlled to 5-8 m 3 / h; when the heavy metal concentration exceeds 200 mg / L, the aeration volume is controlled to 8-10 m 3 / h; when the pH value is kept within the threshold range for 15-30 minutes, the control unit adjusts the metering pump flow rate to a maintenance flow rate of 0.5-1 L / min and simultaneously reduces the aeration volume to 1-3 m 3 / h maintenance value.

[0009] Preferably, in the equipment for treating heavy metal wastewater, a sludge hopper is provided at the bottom of the sedimentation tank, the bottom of the sludge hopper is connected to a sludge discharge pipe, an electric flow control valve is provided on the sludge discharge pipe, and a static pressure level gauge is provided on the inner wall of the sludge hopper for obtaining a sludge deposition height detection value; the control unit is connected to the electric flow control valve for controlling the sludge discharge frequency based on the sludge deposition height detection value in the sludge hopper, and when the sludge deposition height reaches 1 / 3 of the sludge hopper height, the electric flow control valve is controlled to open for sludge discharge for 10-15 minutes; when the sludge deposition height reaches 2 / 3 of the sludge hopper height, the electric flow control valve is controlled to open for sludge discharge for 20-30 minutes.

[0010] Preferably, in the apparatus for treating heavy metal wastewater, the stirring device includes a propeller driven by a motor; and the control unit controls the stirring device and the aeration device based on the following method: the control unit is used to establish a basic correspondence relationship model between the aeration volume Q and the propeller speed N: When 2 m 3 / h≤ Q ≤ 5m 3 / h, N = 50 + 20×(Q-2), the unit of N is rpm; When Q m 3 When / h>5, N = 110 + 30×(Q-5).

[0011] Preferably, in the device for treating heavy metal wastewater, a dissolved oxygen sensor is provided in the reaction tank, and the dissolved oxygen sensor is electrically connected to a control unit, and the control unit is used to dynamically correct the rotation speed N according to the dissolved oxygen detection value D: When D<2.0 mg / L, N = N + 10×(2.0-D); When D ≥ 4.0 mg / L, N = N - 5×(D-4.0).

[0012] Preferably, in the equipment for treating heavy metal wastewater, when the dosing system is started, the control unit is used to synchronously trigger the collaborative response of the stirring device and the aeration device: Within the initial 5 - 10 minutes of adding the sodium sulfide solution, the propeller speed is increased to 180 - 200 rpm, and the aeration volume is increased to 1.2 - 1.5 times the normal range; when the pH value enters the preset threshold range ±0.2, it is restored to adjust the speed according to the basic corresponding relationship model between the aeration volume Q and the propeller speed N.

[0013] Preferably, in the equipment for treating heavy metal wastewater, an online turbidimeter is set in the reaction tank, and the online turbidimeter is electrically connected to the control unit. The control unit is used to dynamically adjust the speed based on the turbidity detection value of the wastewater in the reaction tank: When T > 200 NTU, an additional speed compensation of 20 - 30 rpm is added on the basis of the speed calculated according to the basic corresponding relationship model between the aeration volume Q and the propeller speed N; When T < 50 NTU, a speed compensation reduction of 10 - 20 rpm is made on the basis of the speed calculated according to the basic corresponding relationship model between the aeration volume Q and the propeller speed N.

[0014] Preferably, in the equipment for treating heavy metal wastewater, the control unit is used to establish a basic corresponding relationship model between the sludge discharge flow rate Q and the sludge deposition height H: When 1 / 3 ≤ H ≤ 1 / 2, Q = 0.1 + 0.2×(H - 1 / 3)×3, Q is in the unit of m 3 / h, and H is the percentage of the sludge hopper height; When 1 / 2 < H ≤ 2 / 3, Q = 0.2 + 0.6×(H - 1 / 2)×2; The control unit is used to adjust the opening degree of the electric flow control valve according to the sludge discharge flow rate Q.

[0015] Preferably, in the equipment for treating heavy metal wastewater, an ultrasonic level gauge is set above the sludge hopper to monitor the liquid level drop rate V during the sludge discharge process in real time. When V > 0.3 m / h, the control unit is used to reduce the opening degree of the electric flow control valve until V ≤ 0.3 m / h.

[0016] Preferably, in the equipment for treating heavy metal wastewater, the control unit is used to dynamically correct the sludge discharge flow rate according to the heavy metal concentration detection value C (unit: mg / L) in the reaction tank: When C>150, add 0.05-0.1 m to the sludge discharge flow rate calculated by the basic corresponding relationship model between the sludge discharge flow rate Q and the sludge deposition height H. 3 / h flow compensation; When C<80, the sludge discharge flow rate calculated by the basic corresponding relationship model between the sludge discharge flow rate Q and the sludge deposition height H is reduced by 0.05-0.1 m 3 / h flow compensation.

[0017] Preferably, in the device for treating heavy metal wastewater, the control unit is used to control the opening of the electric flow control valve according to the following method: In the first 5 minutes of mud discharge, set the opening of the electric flow control valve to 70%-80% of the target opening; 5-15 minutes after the mud is discharged, adjust the opening of the electric flow control valve to the target opening; At the end of the mud discharge period (the last 5 minutes), adjust the opening of the electric flow control valve back to 50%-60% of the target opening; The target opening is the opening corresponding to the sludge discharge flow rate calculated according to the basic correspondence relationship model between the sludge discharge flow rate Q and the sludge deposition height H.

[0018] The present invention has at least the following beneficial effects: (1) The present invention significantly improves the sodium sulfide precipitation efficiency and reduces the waste of reagents by real-time monitoring of pH and heavy metal concentration and dynamically adjusting the dosage and aeration volume.

[0019] (2) The present invention avoids the risk of sedimentation tank blockage and reduces the need for manual intervention by controlling the sludge deposition height and sludge discharge frequency in a coordinated manner.

[0020] (3) The present invention optimizes the mixing effect and reduces energy consumption by establishing a mathematical model of aeration volume and propeller speed.

[0021] (4) The present invention regulates the rotation speed by dissolved oxygen feedback, thereby ensuring the stability of the redox conditions in the reaction tank.

[0022] (5) The present invention shortens the pH adjustment time and improves the system response speed by enhancing stirring and aeration at the initial stage of drug addition.

[0023] (6) The present invention adapts to the treatment requirements of high turbidity wastewater through the turbidity compensation mechanism and avoids sediment backmixing.

[0024] (7) The present invention realizes the precision of the sludge discharge process through highly correlated control of the sludge discharge flow rate.

[0025] (8) The present invention prevents the loss of clean water during the sludge discharge process by monitoring the liquid level drop rate.

[0026] (9) The present invention corrects the discharge flow by adjusting the heavy metal concentration, thereby ensuring that the sludge of high-concentration wastewater is discharged in a timely manner.

[0027] (10) The present invention reduces pipeline impact and extends equipment life by adjusting the mud discharge valve opening in stages.

[0028] (11) Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of the equipment for treating heavy metal wastewater provided by the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0031] like Figure 1 As shown, the present invention provides an apparatus for treating heavy metal wastewater, comprising a reaction tank, a stirring device arranged in the reaction tank, a dosing system connected to the reaction tank, an aeration device arranged at the bottom of the reaction tank, and a sedimentation tank connected to the water outlet of the reaction tank; the inner wall of the reaction tank is provided with a pH monitoring probe and a heavy metal concentration monitoring probe, and the pH monitoring probe, the heavy metal concentration monitoring probe, the aeration device and the control unit of the dosing system are electrically connected; the dosing system comprises a drug storage tank, a metering pump and a drug dosing pipeline, and the drug storage tank stores a sodium sulfide solution with a concentration of 10%-30%; the control unit is used to obtain the pH detection value of the pH monitoring probe in real time, and compare the pH detection value with a preset pH threshold range of 8.5-9.5; when the pH detection value is lower than the lower limit of the threshold range, the metering pump is controlled to add the sodium sulfide solution in a first flow range of 1.5-3 L / min; when the pH detection value is higher than the upper limit of the threshold range, the metering pump is controlled to add the sodium sulfide solution at a first flow range of 0.5-1.5 L / min The control unit is also used to dynamically adjust the aeration volume according to the heavy metal concentration detection value of the wastewater in the reaction tank. When the heavy metal concentration is 50-100 mg / L, the aeration volume is controlled to be 2-5 m 3 / h; when the heavy metal concentration is 100-200 mg / L, the aeration volume is controlled to 5-8 m 3 / h; when the heavy metal concentration exceeds 200 mg / L, the aeration volume is controlled to 8-10 m 3 / h; when the pH value is kept within the threshold range for 15-30 minutes, the control unit adjusts the metering pump flow rate to a maintenance flow rate of 0.5-1 L / min and simultaneously reduces the aeration volume to 1-3 m 3 / h maintenance value.

[0032] The reaction tank is made of carbon steel with rubber lining, with a length × width × height of 4 m × 3 m × 3.5 m and an effective volume of 38 m 3 . Online pH electrodes and heavy metal ion selective electrodes are installed on the inner walls of both sides of the pool at a distance of 1 m from the bottom, and the electrode signals are transmitted to the control cabinet via 4-20mA. The stirring device is equipped with a three-blade propeller with a propeller diameter of 800 mm, and the motor achieves stepless speed regulation of 50-200 rpm through a frequency converter. The drug storage tank of the dosing system is equipped with a liquid level alarm, and the flow range of the metering pump is adjustable from 0.1 to 5L / min. The aeration device is supplied with air by a Roots blower, and 12 aeration plates with a diameter of 200 mm are branched out from the main pipeline. The measurement accuracy of the pH electrode is ±0.1, and the response time is <30 seconds; the detection limit of the heavy metal electrode is 0.1 mg / L; the oxygen utilization rate of the aeration plate is ≥28%.

[0033] During the operation phase, after the wastewater enters the reaction tank through the lifting pump, the pH electrode monitors the data in real time. When the pH is detected to be 8.2, the PLC immediately starts the metering pump to add 25% sodium sulfide solution at 2.5 L / min, and at the same time adjusts the aeration volume to 4 m 3 / h. Heavy metal electrode detection Zn 2 + When the concentration reaches 180 mg / L, the PLC will increase the aeration volume to 7 m 3 / h, and simultaneously adjusted the propeller speed to 145 rpm. After 18 minutes of reaction, the pH stabilized within the range of 9.1±0.1, and the system automatically switched to maintenance mode, at which time the dosing rate was reduced to 0.7 L / min and the aeration rate was reduced to 2.5 m³ / h.

[0034] In a preferred embodiment, in the equipment for treating heavy metal wastewater, a sludge hopper is provided at the bottom of the sedimentation tank, the bottom of the sludge hopper is connected to a sludge discharge pipe, an electric flow control valve is provided on the sludge discharge pipe, and a static pressure level gauge is provided on the inner wall of the sludge hopper for obtaining the sludge deposition height detection value; the control unit is connected to the electric flow control valve for controlling the sludge discharge frequency based on the sludge deposition height detection value in the sludge hopper, when the sludge deposition height reaches 1 / 3 of the sludge hopper height, the electric flow control valve is controlled to open for sludge discharge for 10-15 minutes; when the sludge deposition height reaches 2 / 3 of the sludge hopper height, the electric flow control valve is controlled to open for sludge discharge for 20-30 minutes.

[0035] An inverted cone-shaped sludge hopper is set at the bottom of the sedimentation tank. The sludge hopper is made of carbon steel with rubber lining, with a cone angle of 60° and an effective volume of 3m 3 The center of the bottom of the sludge hopper is connected to the mud discharge pipe through a flange. The mud discharge pipe is equipped with an electric flow control valve. The valve uses Siemens SKB62 pneumatic butterfly valve, equipped with a limit switch and positioner, which can achieve precise adjustment of the opening from 0 to 100%.

[0036] A static pressure level gauge, E+H FTM50, is installed on the inner wall of the sludge hopper, 1 meter above the bottom. It has a range of 0-3 meters, an accuracy of ±1 cm, and uses a 4-20 mA output signal. The gauge's 316L stainless steel sensor diaphragm directly contacts the sludge layer, providing real-time monitoring of sludge deposition height. The control unit is connected to the electric flow control valve and level gauge via Profibus.

[0037] During operation, sludge in the sedimentation tank gradually settles and accumulates in the sludge hopper. When the static pressure level gauge detects that the sludge level reaches one-third of the hopper's total height (approximately 1 meter), the control unit immediately initiates a command to open the electric flow control valve to discharge the sludge. The valve slowly opens at 70% for the first five minutes, then fully opens to continue discharging the sludge for 10-12 minutes. During this period, the level gauge continuously monitors the sludge level. The valve automatically closes when the set time is reached or the liquid level drops to a safe threshold.

[0038] When the sludge is settling rapidly and the liquid level reaches two-thirds of the sludge hopper height (approximately 2 meters), the system initiates enhanced sludge discharge mode: the valve opening is 80% for the first five minutes, then remains fully open for the next 15 minutes, and then gradually decreases to 60% opening for the final five minutes. The total sludge discharge time is controlled within 25-28 minutes. This staged sludge discharge method effectively prevents pipe blockage and sludge splashing.

[0039] This sludge discharge system automates sedimentation tank sludge management through precise height detection and intelligent sludge discharge control. Compared to traditional timed sludge discharge methods, it saves over 30% of water consumption while effectively preventing sludge from compacting in the hopper. The system operates stably and reliably, significantly reducing manual operation and maintenance costs.

[0040] In a preferred embodiment, in the apparatus for treating heavy metal wastewater, the stirring device includes a propeller driven by a motor; the control unit controls the stirring device and the aeration device based on the following method: the control unit is used to establish a basic correspondence relationship model between the aeration volume Q and the propeller speed N: When 2 m 3 / h≤ Q ≤ 5m 3 / h, N = 50 + 20×(Q-2), the unit of N is rpm; that is, the speed increases linearly with the aeration rate; When Q m 3 When / h>5, N = 110 + 30×(Q-5), that is, the speed increase rate increases nonlinearly with the aeration volume.

[0041] The stirring device in this embodiment uses an ABB M2BAX 132M three-phase asynchronous motor (power 5.5kW) driving a 316L stainless steel three-blade propeller with a diameter of 600mm. The motor is continuously variable from 50 to 260rpm via a Siemens G120C inverter, which communicates with the control unit via Profibus-DP. The aeration device uses a Raetz GM40 Roots blower with a rated air volume of 10m 3 / h, wind pressure 49kPa.

[0042] When the system starts, the control unit reads the current aeration volume sensor value; calculates the target speed according to a preset algorithm; adjusts the inverter output frequency through the PID control algorithm; monitors the motor current and speed feedback in real time to ensure stable operation; and automatically checks the deviation between the actual speed and the theoretical value every 5 minutes, triggering an alarm if the deviation exceeds ±5%.

[0043] For example, (1) when treating low-concentration wastewater (Q=3m 3 / h): N=50+20×(3-2)=70rpm (2) When treating high concentration wastewater (Q=7m 3 / h): N=110+30×(7-5)=170rpm.

[0044] This embodiment uses a piecewise function to establish a nonlinear relationship between aeration volume and rotational speed. This increases the speed increase slope in high aeration volume areas, enhancing turbulence while avoiding excessive agitation energy consumption at low aeration volumes. By establishing a precise mathematical model of aeration volume and agitation speed, this invention achieves an optimal match between mixing intensity and aeration volume within the reaction tank, ensuring sufficient contact and reaction between the reagent and wastewater while avoiding energy waste caused by excessive agitation. The system automatically adjusts operating parameters based on the processing load, significantly improving processing efficiency and stability.

[0045] In a preferred embodiment, in the apparatus for treating heavy metal wastewater, a dissolved oxygen sensor is provided in the reaction tank, and the dissolved oxygen sensor is electrically connected to a control unit, and the control unit is used to dynamically correct the rotation speed N according to the dissolved oxygen detection value D: When D<2.0 mg / L, N = N + 10×(2.0-D), and the rotation speed is increased to enhance the gas-liquid mass transfer efficiency; When D ≥ 4.0 mg / L, N = N - 5×(D-4.0), and the rotation speed is reduced to reduce energy consumption.

[0046] The reactor is equipped with a Mettler-Toledo InPro6850i dissolved oxygen sensor. This sensor features a titanium alloy housing and PTFE diaphragm, a measurement range of 0-20 mg / L, and an accuracy of ±0.1 mg / L. The sensor collects data every 5 seconds, processes it through digital filtering, and then uploads it to the PLC. The PLC compares the measured value with a threshold value and calculates a speed correction. The PLC then smoothly adjusts the inverter output frequency using a PID algorithm. Motor current fluctuations are monitored in real time to ensure stable speed regulation. An operation log is automatically generated every 30 minutes, recording the dissolved oxygen concentration and the corresponding speed.

[0047] For example, (1) when the dissolved oxygen drops to 1.8 mg / L: the speed increase value = 10 × (2.0-1.8) = 2 rpm; (2) when the dissolved oxygen rises to 4.3 mg / L: the speed decrease value = 5 × (4.3-4.0) = 1.5 rpm.

[0048] This embodiment introduces the real-time detection value of dissolved oxygen as a correction parameter to form a closed-loop control to adapt to the gas-liquid mass transfer requirements under different water quality conditions. The present invention realizes the precise control of the redox conditions in the reaction tank through real-time monitoring and dynamic correction of the dissolved oxygen concentration, ensuring the optimal environment for the heavy metal precipitation reaction. The system can automatically adapt to changes in water quality, optimize stirring energy consumption, and improve the stability of treatment efficiency. This embodiment realizes the precise regulation of the redox environment in the reaction tank through closed-loop control of the dissolved oxygen concentration, ensuring that the heavy metal precipitation reaction is always in the optimal working condition. The system can automatically adapt to fluctuations in the inlet water load, optimize stirring energy consumption while ensuring the treatment effect, and significantly improve the stability and reliability of the system operation.

[0049] In a preferred embodiment, in the equipment for treating heavy metal wastewater, when the dosing system is started, the control unit is used to synchronously trigger the coordinated response of the stirring device and the aeration device: within the initial 5-10 minutes of adding the sodium sulfide solution, the propeller speed is increased to 180-200 rpm, and the aeration volume is increased to 1.2-1.5 times the normal range; when the pH value enters the preset threshold range of ±0.2, the speed is restored to be adjusted according to the basic correspondence model between the aeration volume Q and the propeller speed N.

[0050] The control unit has an embedded three-level control strategy: (1) Dosing trigger phase: after receiving the dosing signal, the collaborative program is started within 0ms, the propeller speed is increased to 190±5rpm, and the aeration volume is linearly increased to 1.35 times the baseline value; (2) Intensified reaction phase (7 minutes): maintain a high-intensity mixing state and monitor the pH change rate in real time; 3) Recovery transition phase: when the pH value enters the range of 8.7-9.3 and remains stable, a 120-second linear transition program is started, and finally switches to the basic control model.

[0051] For example, (1) the metering pump start signal triggers the collaborative program; (2) the system completes the following actions within 3 seconds: the stirring motor frequency increases from 35Hz to 47Hz, the aeration fan frequency increases from 45Hz to 60Hz, (3) the enhanced reaction state is maintained for 7 minutes; (4) when the pH value is stable at 9.0±0.3 for 2 minutes: the speed is reduced to the calculated value at a rate of 2rpm / s, and the aeration volume is increased by 0.5m 3 / h·s rate adjustment.

[0052] This example addresses the need for a rapid reaction during the initial sodium sulfide addition phase by designing a pulsed, coordinated strategy that briefly enhances stirring and aeration intensity to increase the nucleation rate of heavy metal sulfides. By synergizing enhanced stirring and aeration during the initial dosing phase, this invention significantly improves the diffusion efficiency and reaction rate of the agent, ensuring the rapid formation of a stable precipitation of heavy metal ions. The system intelligently identifies the stage of reaction completion and smoothly transitions to normal operation, ensuring effective treatment while avoiding energy waste, resulting in a highly efficient and energy-efficient process.

[0053] In a preferred embodiment, in the apparatus for treating heavy metal wastewater, an online turbidity meter is provided in the reaction tank, and the online turbidity meter is electrically connected to a control unit, and the control unit is used to dynamically adjust the rotation speed based on the turbidity detection value of the wastewater in the reaction tank: When T>200 NTU, an additional 20-30 rpm speed compensation is added to the speed calculated based on the basic correspondence model between aeration volume Q and propeller speed N; When T<50 NTU, a speed compensation of 10-20 rpm is reduced from the speed calculated based on the basic correspondence model between aeration volume Q and propeller speed N.

[0054] A HACH Solitaxsc turbidity meter is installed in the reaction tank. The sensor uses a sapphire optical window and a 316L stainless steel housing, has a measuring range of 0-1000 NTU, and is equipped with an automatic cleaning brush.

[0055] When the system is working, the turbidimeter collects data every 30 seconds and transmits it to the PLC; the PLC judges the current turbidity range; calculates the target rotational speed and outputs it to the frequency converter; monitors the change of the motor load in real time; and automatically executes the sensor cleaning program every 2 hours.

[0056] For example, when it is detected that T = 250 NTU: the final rotational speed = the basic rotational speed + 25 rpm; when it is detected that T = 30 NTU: the final rotational speed = the basic rotational speed - 15 rpm.

[0057] In this embodiment, the cooperation parameters are dynamically adjusted according to the turbidity of the wastewater, enhancing the mixing effect at high turbidity and reducing energy consumption at low turbidity, achieving refined control. The present invention realizes the precise regulation of the solid-liquid mixing state in the reaction tank through the closed-loop control of turbidity monitoring and dynamic compensation. The system can automatically optimize the stirring intensity according to the real-time turbidity, ensuring full mixing under high turbidity conditions and avoiding over-stirring under low turbidity conditions, significantly improving the stability of the treatment effect and reducing energy consumption.

[0058] In a preferred embodiment, in the equipment for treating heavy metal wastewater, the control unit is used to establish a basic corresponding relationship model between the sludge discharge flow rate Q and the sludge deposition height H: When 1 / 3 ≤ H ≤ 1 / 2, Q = 0.1 + 0.2×(H - 1 / 3)×3, the unit of Q is m 3 / h, H is the percentage of the sludge hopper height, that is, the flow rate increases linearly with the settlement height; When 1 / 2 < H ≤ 2 / 3, Q = 0.2 + 0.6×(H - 1 / 2)×2, that is, the flow rate growth rate increases non-linearly with the deposition height; The control unit is used to adjust the opening of the electric flow control valve according to the sludge discharge flow rate Q.

[0059] When the system is working, the liquid level gauge monitors the sludge height in real time; the PLC calculates the value of H every 10 seconds; calculates the target flow rate Q according to the model; converts it into a valve opening instruction (0 - 100%); outputs a 4 - 20 mA control signal; and records historical data for optimization.

[0060] For example, when 33.3% ≤ H ≤ 50%: Q = 0.1 + 0.6×(H - 0.333); when 50% < H ≤ 66.7%: Q = 0.2 + 1.2×(H - 0.5).

[0061] This embodiment uses a piecewise function to establish a nonlinear relationship between sludge deposition height and sludge discharge flow rate. This increases the flow rate acceleration slope in areas of high deposition height, ensuring efficient sludge discharge while avoiding drastic liquid level fluctuations. By establishing a precise mathematical model for sludge discharge, this invention achieves intelligent matching of discharge flow rate and sludge deposition height, ensuring timely sludge discharge from the sedimentation tank while avoiding the waste of clean water caused by excessive discharge. The system automatically adapts to different sludge characteristics, optimizing sludge discharge efficiency and significantly reducing the need for manual operation.

[0062] In a preferred embodiment, in the equipment for treating heavy metal wastewater, an ultrasonic level meter is provided on the upper part of the sludge hopper for real-time monitoring of the liquid level drop rate V during the sludge discharge process. When V>0.3 m / h, the control unit is used to reduce the opening of the electric flow control valve until V ≤ 0.3 m / h.

[0063] When the system is working, the level gauge continuously measures the liquid level; the PLC calculates the V value every 10 seconds; determines whether adjustment is needed; calculates and outputs the new opening; monitors the actual descent rate change; and records key parameters every 5 minutes.

[0064] For example, the liquid level change rate V (m / h) is calculated in real time. When V>0.3m / h: new opening = current opening × [1-0.1×(V-0.3) / 0.1], the adjustment cycle is 30 seconds, and the minimum opening limit is 10%.

[0065] This embodiment monitors liquid level changes in real time during sludge discharge, using closed-loop control to prevent water flow disturbances caused by excessive sludge discharge and maintain hydraulic stability in the sedimentation tank. By monitoring the rate of liquid level drop in real time and dynamically adjusting valve opening, this invention effectively prevents clear water carryover during sludge discharge, ensuring sludge concentration. The system intelligently identifies sludge discharge status and automatically optimizes the discharge rate, ensuring efficient sludge discharge while minimizing water waste.

[0066] In a preferred embodiment, in the device for treating heavy metal wastewater, the control unit is used to dynamically correct the sludge discharge flow rate according to the heavy metal concentration detection value C (unit: mg / L) in the reaction tank: When C>150, a flow compensation of 0.05-0.1 m³ / h is added to the sludge discharge flow calculated by the basic correspondence model between the sludge discharge flow Q and the sludge deposition height H; When C<80, the sludge discharge flow rate calculated by the basic corresponding relationship model between the sludge discharge flow rate Q and the sludge deposition height H is reduced by 0.05-0.1 m 3 / h flow compensation.

[0067] When the system is working, the online analyzer regularly detects the heavy metal concentration; the PLC receives and verifies the data; calculates the compensation amount according to the model; converts it into a valve opening instruction; outputs a control signal; and records the operating parameters.

[0068] For example, when C > 150 mg / L: Q_comp = Q_base + 0.08; when 80 ≤ C ≤ 150 mg / L: Q_comp = Q_base; when C < 80 mg / L: Q_comp = Q_base - 0.08. Q_comp is the new sludge discharge flow rate, and Q_base is the sludge discharge flow rate calculated based on the basic correspondence model between the sludge discharge flow rate Q and the sludge deposition height H. The compensation amount can be adjusted within a range of ±30% based on actual needs.

[0069] This embodiment dynamically adjusts the sludge discharge flow rate based on the heavy metal concentration in the wastewater, enhancing sludge discharge efficiency under high-concentration conditions and reducing the risk of heavy metal redissolution in the sludge. By intelligently linking heavy metal concentration and sludge discharge flow rate, this invention achieves precise control of sludge discharge. The system automatically adjusts discharge intensity based on pollution load, ensuring timely treatment of high-concentration wastewater while avoiding resource waste at low concentrations, significantly improving the adaptability and stability of the treatment system.

[0070] In a preferred embodiment, in the device for treating heavy metal wastewater, the control unit is used to control the opening of the electric flow control valve according to the following method: In the first 5 minutes of mud discharge, set the opening of the electric flow control valve to 70%-80% of the target opening; 5-15 minutes after the mud is discharged, adjust the opening of the electric flow control valve to the target opening; At the end of the mud discharge period (the last 5 minutes), adjust the opening of the electric flow control valve back to 50%-60% of the target opening; The target opening is the opening corresponding to the sludge discharge flow rate calculated according to the basic correspondence relationship model between the sludge discharge flow rate Q and the sludge deposition height H.

[0071] When the system is working, it calculates the target opening, outputs the set value according to the stage, monitors the actual opening feedback, records the operation curve, and handles abnormal situations.

[0072] For example, when the target opening is 60%, 0-5 minutes: 45% opening; 5-15 minutes: 60% opening; the last 5 minutes: 33% opening.

[0073] Compared with traditional manual control methods, this equipment reduces chemical consumption by 22%, aeration energy consumption by 18%, and the heavy metal index of the effluent stably meets the first-level standard of the "Integrated Sewage Discharge Standard" GB8978-1996.

[0074] This embodiment employs a three-stage control system: "soft start - stable sludge discharge - soft shut-off," avoiding the water hammer effect and sludge disturbance caused by traditional one-time fully open / close valves. By precisely controlling the valve opening in stages, this invention achieves smooth start and stop times during the sludge discharge process, effectively preventing water hammer and sludge deposit disturbance, ensuring system stability in sludge discharge, and extending the equipment's service life.

[0075] Equipment parameters in this application, including reactor dimensions, propeller diameter (800 mm), and number of aeration discs (12), are derived from engineering calculations during the equipment design phase or actual manufacturing standards. Sensor accuracy, including pH electrode measurement accuracy (±0.1), heavy metal electrode detection limit (0.1 mg / L), and dissolved oxygen sensor range (0-20 mg / L), is cited from the sensor manufacturer's specifications.

[0076] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and exemplary embodiments. They can be applied to a variety of fields suitable for the present invention. Further modifications will be readily apparent to those skilled in the art. Therefore, the present invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims

1. A device for treating heavy metal wastewater, characterized in that: It includes a reaction tank, a stirring device arranged in the reaction tank, a dosing system connected to the reaction tank, an aeration device arranged at the bottom of the reaction tank, and a sedimentation tank connected to the water outlet of the reaction tank; The inner wall of the reaction tank is provided with a pH monitoring probe and a heavy metal concentration monitoring probe, and the pH monitoring probe, the heavy metal concentration monitoring probe, the aeration device and the control unit of the dosing system are electrically connected; The dosing system includes a drug storage tank, a metering pump and a drug dosing pipeline. The drug storage tank stores a sodium sulfide solution with a concentration of 10%-30%; The control unit is used to obtain the pH detection value of the pH monitoring probe in real time and compare the pH detection value with a preset pH threshold range of 8.5-9.5; when the pH detection value is lower than the lower limit of the threshold range, control the metering pump to add sodium sulfide solution at a first flow rate range of 1.5-3 L / min; when the pH detection value is higher than the upper limit of the threshold range, control the metering pump to add acid neutralizer at a second flow rate range of 0.5-1.5 L / min; The control unit is also used to dynamically adjust the aeration volume according to the heavy metal concentration detection value of the wastewater in the reaction tank. When the heavy metal concentration is 50-100 mg / L, the aeration volume is controlled to be 2-5 m 3 / h; when the heavy metal concentration is 100-200 mg / L, the aeration volume is controlled to 5-8 m 3 / h; when the heavy metal concentration exceeds 200 mg / L, the aeration volume is controlled to 8-10 m 3 / h; when the pH value is kept within the threshold range for 15-30 minutes, the control unit adjusts the metering pump flow rate to a maintenance flow rate of 0.5-1L / min and simultaneously reduces the aeration volume to 1-3 m 3 / h maintenance value.

2. The device for treating heavy metal wastewater according to claim 1, characterized in that: A sludge hopper is provided at the bottom of the sedimentation tank, and a sludge discharge pipe is connected to the bottom of the sludge hopper. An electric flow control valve is provided on the sludge discharge pipe. A static pressure level gauge is provided on the inner wall of the sludge hopper for obtaining the sludge deposition height detection value; the control unit is connected to the electric flow control valve and is used to control the sludge discharge frequency based on the sludge deposition height detection value in the sludge hopper. When the sludge deposition height reaches 1 / 3 of the sludge hopper height, the electric flow control valve is controlled to open for sludge discharge for 10-15 minutes; when the sludge deposition height reaches 2 / 3 of the sludge hopper height, the electric flow control valve is controlled to open for sludge discharge for 20-30 minutes.

3. The device for treating heavy metal wastewater according to claim 2, characterized in that: The stirring device includes a propeller driven by a motor; the control unit controls the stirring device and the aeration device based on the following method: the control unit is used to establish a basic corresponding relationship model between the aeration volume Q and the propeller speed N: When 2 m 3 / h≤ Q ≤ 5m 3 / h, N = 50 + 20×(Q-2), the unit of N is rpm; When Q m 3 When / h > 5, N = 110 + 30×(Q-5).

4. The device for treating heavy metal wastewater according to claim 3, characterized in that: A dissolved oxygen sensor is provided in the reaction tank, and the dissolved oxygen sensor is electrically connected to a control unit, and the control unit is used to dynamically correct the rotation speed N according to the dissolved oxygen detection value D: When D <2.0 mg / L, N = N + 10×(2.0-D); When D ≥ 4.0 mg / L, N = N - 5×(D-4.0).

5. The device for treating heavy metal wastewater according to claim 4, characterized in that: When the dosing system is started, the control unit is used to synchronously trigger the coordinated response of the stirring device and the aeration device: Within the initial 5-10 minutes of adding sodium sulfide solution, the propeller speed is increased to 180-200 rpm, and the aeration volume is increased to 1.2-1.5 times the normal range; when the pH value enters the preset threshold range of ±0.2, the speed is adjusted according to the basic correspondence model between the aeration volume Q and the propeller speed N.

6. The device for treating heavy metal wastewater according to claim 5, characterized in that: An online turbidity meter is set in the reaction tank, and the online turbidity meter is electrically connected to the control unit. The control unit is used to dynamically adjust the rotation speed based on the turbidity detection value of the wastewater in the reaction tank: When T > 200 NTU, an additional rotational speed compensation of 20 - 30 rpm is added to the rotational speed calculated based on the basic correspondence relationship model of the aeration volume Q and the propeller rotational speed N. When T < 50 NTU, a rotational speed compensation of 10 - 20 rpm is reduced from the rotational speed calculated based on the basic correspondence relationship model of the aeration volume Q and the propeller rotational speed N.

7. The device for treating heavy metal wastewater according to claim 6, characterized in that: The control unit is used to establish a basic correspondence relationship model between the sludge discharge flow rate Q and the sludge deposition height H: When 1 / 3 ≤ H ≤ 1 / 2, Q = 0.1 + 0.2×(H-1 / 3)×3, where Q is expressed in m. 3 / h, H is the percentage of sludge hopper height; When 1 / 2 < H ≤ 2 / 3, Q = 0.2 + 0.6×(H - 1 / 2)×2; The control unit is used to adjust the opening degree of the electric flow control valve according to the sludge discharge flow rate Q.

8. The device for treating heavy metal wastewater according to claim 7, characterized in that: An ultrasonic level gauge is arranged at the upper part of the sludge hopper to monitor the liquid level drop rate V during the sludge discharge process in real time. When V > 0.3 m / h, the control unit is used to reduce the opening degree of the electric flow control valve until V ≤ 0.3 m / h.

9. The device for treating heavy metal wastewater according to claim 8, characterized in that: The control unit is used to dynamically correct the sludge discharge flow rate according to the detected value C (unit: mg / L) of the heavy metal concentration in the reaction tank: When C > 150, add 0.05-0.1 m to the sludge discharge flow rate calculated by the basic correspondence model between the sludge discharge flow rate Q and the sludge deposition height H. 3 / h flow compensation; When C <80, the sludge discharge flow rate calculated by the basic correspondence model between the sludge discharge flow rate Q and the sludge deposition height H is reduced by 0.05-0.1 m 3 / h flow compensation.

10. The device for treating heavy metal wastewater according to claim 9, characterized in that: The control unit is used to control the opening degree of the electric flow control valve according to the following method: In the first 5 minutes at the beginning of the sludge discharge, the opening degree of the electric flow control valve is set to 70% - 80% of the target opening degree; In the 5 - 15 minutes of the sludge discharge, the opening degree of the electric flow control valve is adjusted to the target opening degree; In the final stage of the sludge discharge (the last 5 minutes), the opening degree of the electric flow control valve is adjusted back to 50% - 60% of the target opening degree; Among them, the target opening degree is the opening degree corresponding to the sludge discharge flow rate calculated according to the basic correspondence relationship model between the sludge discharge flow rate Q and the sludge deposition height H.

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