Magnetic nanomaterial adsorption separation system and method in heavy metal treatment of sewage

Abstract

This invention relates to the field of wastewater treatment technology, specifically to a magnetic nanomaterial adsorption and separation system and method for heavy metal treatment in wastewater. The method provided by this invention includes the following steps: based on process characterization parameters used to characterize the removal state of heavy metals in wastewater and to characterize the separability state of magnetic nanomaterials when a preset recovery rate is achieved, determining the improvement trend of extending the adsorption time after the current sampling time on the removal effect of heavy metals in wastewater, and determining an effective purification cutoff time based on the improvement trend; and based on the process characterization parameters, determining the deterioration trend of extending the adsorption time after the current sampling time on the implementation conditions of magnetic separation, and determining an allowable separation cutoff time based on the deterioration trend; determining a critical switching time based on the earlier of the effective purification cutoff time and the allowable separation cutoff time, and initiating magnetic separation when the time interval between the current sampling time and the critical switching time meets a preset start-up condition.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a magnetic nanomaterial adsorption and separation system and method for heavy metal treatment in wastewater. Background Technology

[0002] During water treatment, water bodies may contain heavy metal ions such as lead, cadmium, chromium, and copper. Therefore, it is necessary to remove these heavy metal ions from the water through appropriate treatment methods.

[0003] In existing water treatment technologies, magnetic nanoparticles are widely used in heavy metal removal processes due to their large specific surface area, high adsorption efficiency, and ability to be rapidly separated and recovered using an external magnetic field. When using these materials for water treatment, the magnetic nanoparticles are typically added to the water to adsorb heavy metal ions, and then magnetically separated and recovered using an external magnetic field after the adsorption reaction is complete.

[0004] In actual operation, the initiation of the magnetic separation process usually relies on a preset reaction time or operational experience. Due to differences in heavy metal ion concentration, pH, temperature, and water flow conditions in different water bodies, the adsorption reaction rate of magnetic nanomaterials for heavy metal ions may vary significantly, making it difficult to adapt a fixed reaction time to different treatment conditions. In this situation, if the magnetic separation initiation timing is not set appropriately, separation may occur before the adsorbent material has fully completed adsorption, resulting in insufficient removal of heavy metal ions; or the adsorbent material may remain in the water for too long, increasing particle aggregation and system energy consumption. Summary of the Invention

[0005] In one embodiment of the present invention, the method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials provided by the present invention includes the following steps during the adsorption of heavy metals in wastewater by a batch of magnetic nanomaterials:

[0006] Obtain process characterization parameters, which include at least a first process characterization parameter for characterizing the removal state of heavy metals in wastewater, and a second process characterization parameter for characterizing the separability state of magnetic nanomaterials when a preset recovery rate is achieved.

[0007] Based on the process characterization parameters, the improvement trend of the removal effect of heavy metals in wastewater after extending the adsorption time after the current sampling time is determined, and the effective purification cutoff time is determined according to the improvement trend. The effective purification cutoff time is used to characterize the time when the degree of new purification improvement brought about by extending the adsorption time is reduced to the preset minimum purification requirement.

[0008] Based on the process characterization parameters, the deterioration trend of the magnetic separation implementation conditions caused by extending the adsorption time after the current sampling time is determined, and the separation allowable cutoff time is determined according to the deterioration trend. The separation allowable cutoff time is used to characterize the time when the degree of deterioration of the magnetic separation implementation conditions caused by extending the adsorption time reaches the preset allowable upper limit.

[0009] The critical switching time is determined based on the earlier of the effective purification cutoff time and the permissible separation cutoff time. Magnetic separation is initiated when the time interval between the current sampling time and the critical switching time meets the preset start-up conditions.

[0010] In some embodiments, the method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials provided by the present invention, wherein...

[0011] The first process characterization parameters include at least one of the following: the concentration of dissolved heavy metals in the wastewater at the current sampling time, the change in heavy metal concentration between adjacent sampling times, the amount of heavy metals removed per unit sampling time, and the residual difference between the concentration of heavy metals in the wastewater at the current sampling time and the target discharge concentration.

[0012] The second process characterization parameters include at least one of the following: separation time required to achieve a preset recovery rate for the current batch of magnetic nanomaterials at the current sampling time under the rated magnetic field strength of the magnetic separation system and separation energy consumption per unit processing volume.

[0013] In some embodiments, the second process characterization parameter is obtained through the following steps:

[0014] Obtain wastewater state parameters and particle behavior characteristic parameters at the current sampling time;

[0015] The wastewater state parameters and the particle behavior characteristic parameters are input into the prediction model. The prediction model is used to characterize the mapping relationship between the wastewater state parameters, the particle behavior characteristic parameters and the separable state of the magnetic nanomaterials when the preset recovery rate is reached.

[0016] Based on the prediction model, the predicted result of the separable state of the magnetic nanomaterial at the current sampling time when the preset recovery rate is reached is output.

[0017] The predicted results of the separable state are used as the second process characterization parameters.

[0018] In some embodiments, obtaining the second process characterization parameter further includes the following steps:

[0019] Based on different preset recovery rates, different prediction models are constructed. Each prediction model characterizes the mapping relationship between wastewater state parameters, particle behavior characteristic parameters and the separable state of magnetic nanomaterials at a preset recovery rate.

[0020] Obtain the current preset recovery rate set in the current prediction process, select the corresponding prediction model based on the current preset recovery rate, and then input the wastewater state parameters and particle behavior characteristic parameters at the current sampling time into the selected prediction model.

[0021] In some embodiments, determining the improvement trend of heavy metal removal efficiency in wastewater by extending the adsorption time after the current sampling time based on the process characterization parameters includes the following steps:

[0022] Obtain the first process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time;

[0023] Based on the first process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time, the relationship between the concentration of heavy metals in wastewater and time is obtained.

[0024] Based on the relationship between the concentration of heavy metals in the wastewater and time, the degree of improvement in purification corresponding to different extended adsorption times after the current sampling time is obtained.

[0025] The improvement trend is determined by the degree of improvement in purification corresponding to different extended adsorption times after the current sampling time.

[0026] In some embodiments, determining the deterioration trend of the magnetic separation implementation conditions after extending the adsorption time following the current sampling time based on the process characterization parameters includes the following steps:

[0027] Obtain the second process characterization parameters corresponding to the current sampling time and at least one sampling time prior to the current sampling time;

[0028] Based on the second process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time, the relationship between the magnetic separation implementation conditions and time is obtained.

[0029] Based on the relationship between the magnetic separation implementation conditions and time, the degree of new deterioration corresponding to different extended adsorption times after the current sampling time is obtained;

[0030] The deterioration trend is determined based on the degree of new deterioration corresponding to different extended adsorption times after the current sampling time.

[0031] In some embodiments, the preset startup condition includes one of the following:

[0032] The time interval between the current sampling time and the critical switching time is less than or equal to a preset time interval threshold.

[0033] Maintaining the adsorption state at the current sampling time will cause the actual execution time to exceed the critical switching time.

[0034] In some embodiments, for the adsorption process of multiple consecutive batches of magnetic nanomaterials, the magnetic separation is characterized by being continuously controlled in the following manner:

[0035] Obtain the actual magnetic separation result parameters of the previous batch of magnetic nanomaterials;

[0036] Based on the actual magnetic separation results parameters, the magnetic separation initiation conditions for the next batch of magnetic nanomaterials are adjusted.

[0037] In some embodiments, the actual magnetic separation result parameter is the actual separation recovery rate. The step of adjusting the magnetic separation start-up conditions for the next batch of magnetic nanomaterials based on the actual magnetic separation result parameter includes the following steps:

[0038] When the actual separation recovery rate is lower than the preset recovery rate, the preset time interval threshold in the magnetic separation start-up conditions for the next batch of magnetic nanomaterials is increased.

[0039] When the actual separation recovery rate is higher than the preset recovery rate, the preset time interval threshold in the magnetic separation start-up conditions for the next batch of magnetic nanomaterials is reduced.

[0040] Based on the above embodiments of the method for adsorption and separation of magnetic nanomaterials in wastewater heavy metal treatment, some embodiments also provide a magnetic nanomaterial adsorption and separation system for wastewater heavy metal treatment, which includes:

[0041] A process characterization parameter acquisition unit is used to acquire process characterization parameters, which include at least a first process characterization parameter for characterizing the removal state of heavy metals in wastewater, and a second process characterization parameter for characterizing the separable state of magnetic nanomaterials when a preset recovery rate is achieved.

[0042] The purification side boundary determination unit is used to determine the improvement trend of the removal effect of heavy metals in wastewater by extending the adsorption time after the current sampling time based on the process characterization parameters, and to determine the effective purification cutoff time according to the improvement trend. The effective purification cutoff time is used to characterize the time when the degree of new purification improvement brought about by extending the adsorption time is reduced to the preset minimum purification requirement.

[0043] The separation side boundary determination unit is used to determine the deterioration trend of the magnetic separation implementation conditions after the current sampling time by extending the adsorption time based on the process characterization parameters, and to determine the separation allowable cutoff time according to the deterioration trend. The separation allowable cutoff time is used to characterize the time when the degree of deterioration of the magnetic separation implementation conditions caused by extending the adsorption time reaches the preset allowable upper limit.

[0044] The magnetic separation start control unit is used to determine the critical switching time based on the earlier of the effective purification cutoff time and the permissible separation cutoff time, and to start magnetic separation when the time interval between the current sampling time and the critical switching time meets the preset start conditions.

[0045] The magnetic nanomaterial adsorption and separation system and method for heavy metal treatment in wastewater provided by this invention have gains including at least:

[0046] This invention obtains a first process characterization parameter for characterizing the removal state of heavy metals in wastewater and a second process characterization parameter for characterizing the separable state of magnetic nanomaterials when a preset recovery rate is achieved. It then determines the effective cutoff time for purification and the allowable cutoff time for separation, and uses the earlier of the two times to determine the critical switching time. This enables dynamic determination of the magnetic separation start-up timing and improves the accuracy of switching from the adsorption stage to the magnetic separation stage.

[0047] Furthermore, by inputting the wastewater state parameters and particle behavior characteristic parameters at the current sampling time into the prediction model corresponding to the preset recovery rate, the predicted results of the separable state of the magnetic nanomaterial are output as the characterization parameters of the second process. This transforms the separable state, which is difficult to obtain in real time, into parameters that can be predicted online, thereby improving the timeliness and continuity of obtaining the characterization parameters of the second process and the accuracy of determining the separation boundary.

[0048] Furthermore, by obtaining the actual separation and recovery rate of the previous batch of magnetic nanomaterials and correcting the preset time interval threshold in the magnetic separation start-up conditions of the next batch of magnetic nanomaterials, the magnetic separation start-up timing of subsequent batches can be dynamically adjusted according to the actual separation effect of the previous batches, thereby forming a closed-loop correction mechanism and improving the accuracy, stability and adaptability of magnetic separation start-up control under continuous operation conditions. Attached Figure Description

[0049] From the following description of embodiments in conjunction with the accompanying drawings, aspects, features, and advantages of the present invention will become clearer and more readily understood, in which:

[0050] Figure 1 This is a schematic diagram of the process for the adsorption and separation of magnetic nanomaterials in wastewater heavy metal treatment provided by the present invention.

[0051] Figure 2A schematic flowchart illustrating the steps for obtaining second process characterization parameters provided in one embodiment of the present invention;

[0052] Figure 3 A schematic flowchart illustrating the steps for obtaining an improvement trend based on a first process characterization parameter, provided as an embodiment of the present invention;

[0053] Figure 4 A schematic flowchart illustrating the steps for obtaining a deterioration trend based on a second process characterization parameter, provided as an embodiment of the present invention;

[0054] Figure 5 This is a schematic diagram of the functional units of the magnetic nanomaterial adsorption and separation system for heavy metal treatment in wastewater provided by the present invention. Detailed Implementation

[0055] To facilitate understanding of the present invention by those skilled in the art, several embodiments are now described in detail with reference to the accompanying drawings. It should be understood that the embodiments are for illustrative purposes only and not for limiting the scope of protection of the present invention; the scope of protection of the present invention is defined by the claims, and includes equivalent schemes and equivalent transformations of the claims.

[0056] In some wastewater treatment processes, magnetic nanomaterials are added to the adsorption reaction unit in batches. Each batch of magnetic nanomaterials comes into contact with the wastewater to be treated, adsorbs heavy metals in the wastewater, and remains in the adsorption system until the formal magnetic separation and recovery are completed.

[0057] In one embodiment, for the adsorption process of any batch of magnetic nanomaterials in the above-mentioned wastewater treatment process, by means of... Figure 1 Method for controlling magnetic separation:

[0058] S01. Obtain process characterization parameters, which are used to characterize the removal status of heavy metals in wastewater and the separability of magnetic nanomaterials when a preset recovery rate is achieved.

[0059] In this embodiment, the process characterization parameters are a set of parameters used to reflect the removal of heavy metals and the feasibility of magnetic separation during the adsorption process of the current batch of magnetic nanomaterials.

[0060] Furthermore, the process characterization parameters include at least a first process characterization parameter for characterizing the removal state of heavy metals in wastewater, and at least a second process characterization parameter for characterizing the separability state of magnetic nanomaterials when a preset recovery rate is achieved.

[0061] In some specific embodiments, the first process characterization parameters include at least one of the following: the concentration of dissolved heavy metals in the wastewater at the current sampling time, the change in heavy metal concentration between adjacent sampling times, the amount of heavy metals removed per unit sampling time, and the remaining difference between the concentration of heavy metals in the wastewater at the current sampling time and the target emission concentration.

[0062] Furthermore, the first process characterization parameters can be obtained through online detection devices or automatic sampling devices. Specifically, online detection points can be set on the effluent side of the adsorption reaction unit, in the circulation return pipeline, or in the reaction tank to continuously monitor the concentration of dissolved heavy metals in the current wastewater; or wastewater samples can be collected according to a preset sampling cycle, and the concentration of dissolved heavy metals in the wastewater can be determined using chemical analysis equipment or electrochemical detection devices.

[0063] In some specific embodiments, the second process characterization parameters include at least one of the following: separation time required to achieve a preset recovery rate for the current batch of magnetic nanomaterials at the current sampling time under the rated magnetic field strength of the magnetic separation system and separation energy consumption per unit processing volume.

[0064] The preset recovery rate is a separation and recovery target set in advance for the current batch of magnetic nanomaterials when performing magnetic separation. It can be set according to the design recovery capacity of the magnetic separation device, the material recycling requirements and / or the control requirements of the wastewater treatment process on the recovery efficiency.

[0065] Furthermore, the second process characterization parameters can be obtained through a bypass test unit or a local trial magnetic separation method; for example, a rated magnetic field is applied to the wastewater in the bypass test unit to monitor the migration response of the magnetic nanomaterials under the action of the magnetic field, thereby determining the separation time and / or the separation energy consumption per unit processing volume when the preset recovery rate is achieved.

[0066] Because data acquisition methods such as bypass test units / local trial magnetic separation are time-consuming, it is difficult to characterize the separable state of magnetic nanomaterials in a timely and continuous manner, thus affecting the timeliness and accuracy of determining the magnetic separation start-up timing. In some implementations, the second process characterization parameters are predicted based on the wastewater state parameters and particle behavior characteristic parameters at the current sampling time.

[0067] In this part of the implementation, the second process characterization parameters are specifically obtained through, for example... Figure 2 The steps shown are used to make predictions based on the wastewater state parameters and particle behavior characteristic parameters at the current sampling time:

[0068] S011. Obtain the wastewater state parameters and particle behavior characteristic parameters at the current sampling time.

[0069] Furthermore, the wastewater state parameters are used to characterize the environmental conditions of the wastewater treatment system at the current sampling time, and include at least one of the following: heavy metal concentration, pH value, temperature, and flow state in the current wastewater; specifically, the wastewater state parameters can be obtained online through a heavy metal detection device, a pH sensor, a temperature sensor, and a flow detection device.

[0070] Furthermore, the particle behavior characteristic parameters are used to characterize the behavior of the magnetic nanomaterials at the current sampling time, and include at least one of particle concentration and magnetization response intensity; specifically, they can be obtained online by a turbidity detection device, an optical scattering detection device, a magnetic sensor, or other detection devices that can reflect changes in particle concentration and magnetic response.

[0071] Among them, particle concentration is used to reflect the aggregation or dispersion changes of magnetic nanomaterials during the adsorption process, and magnetization response intensity is used to reflect the separation response capability of magnetic nanomaterials under the action of an external magnetic field. Since the conditions required for magnetic nanomaterials to reach the preset recovery rate are jointly affected by the current wastewater environmental conditions, as well as the aggregation state and magnetic response capability of magnetic nanomaterials, this embodiment predicts the subsequent separability of magnetic nanomaterials by jointly using the particle behavior of magnetic nanomaterials and the state of wastewater, which serves as the input for predicting the characterization parameters of the second process.

[0072] S012. Input the wastewater state parameters and the particle behavior characteristic parameters into the prediction model, and based on the input prediction model, output the prediction result of the separable state of the magnetic nanomaterial at the current sampling time when the preset recovery rate is reached.

[0073] Furthermore, the prediction model is used to characterize the mapping relationship between wastewater state parameters, particle behavior characteristic parameters and the separable state of magnetic nanomaterials when a preset recovery rate is achieved. It can be constructed using empirical fitting, regression analysis, machine learning or a model based on particle migration mechanism. As long as it can output the corresponding separable state prediction result based on the current wastewater state parameters and the current particle behavior characteristic parameters, it can be applied to this invention.

[0074] In some specific implementations, the prediction model is constructed based on historical calibration sample data, which includes at least: wastewater state parameters at the historical sampling time, particle behavior characteristic parameters at the historical sampling time, and corresponding separable state data of magnetic nanomaterials when a preset recovery rate is achieved, that is, at least one of the magnetic field strength, separation time, and separation energy consumption per unit processing volume required to achieve the preset recovery rate.

[0075] In these specific implementations, the separable state data is obtained through a bypass test unit or a local trial magnetic separation method. That is, during the historical sample collection process, a rated magnetic field is applied to the magnetic nanomaterials in the wastewater, and the magnetic field strength, separation time and / or separation energy consumption per unit processing volume corresponding to the time when the preset recovery rate is achieved are recorded, thereby forming a calibration sample corresponding to the wastewater state parameters and particle behavior characteristic parameters at the corresponding sampling time.

[0076] It should be noted that the separable state data in the historical calibration sample data and the separable state prediction results output at the current sampling time should correspond to the same preset recovery rate to ensure the consistency of the mapping relationship between the training and application phases.

[0077] In these specific implementations, historical calibration sample data is input into the prediction model training module to establish a mapping relationship between wastewater state parameters, particle behavior characteristic parameters, and separable state data. Furthermore, the wastewater state parameters and particle behavior characteristic parameters at the current sampling time are input into the trained and validated prediction model, which then outputs the predicted results of the separable state of the current batch of magnetic nanomaterials when the preset recovery rate is achieved.

[0078] Furthermore, the separable state prediction result is used to characterize the magnetic separation implementation conditions corresponding to achieving the preset recovery rate when performing magnetic separation on the current batch of magnetic nanomaterials at the current sampling time. It includes at least the predicted separation time and / or the predicted separation energy consumption per unit processing volume required for the magnetic nanomaterials to achieve the preset recovery rate at the current sampling time.

[0079] S013. Use the predicted results of the separable state as the second process characterization parameters.

[0080] In this embodiment, the separable state prediction result is used as the second process characterization parameter corresponding to the current sampling time, and is associated with and stored with the corresponding sampling time and the corresponding batch for subsequent steps to call.

[0081] To ensure the consistency between the historical calibration sample data used for model construction and the current prediction task at the preset recovery rate, and to avoid the cross-application of separable state prediction results under different preset recovery rates, in some specific implementations, the acquisition of the second process characterization parameters involved in steps S011 to S013 further includes the following steps:

[0082] S001. Based on different preset recovery rates, different prediction models are constructed. Each prediction model represents the mapping relationship between wastewater state parameters, particle behavior characteristic parameters and the separable state of magnetic nanomaterials at a preset recovery rate.

[0083] S002. Obtain the current preset recovery rate set in the current prediction process, and select the corresponding prediction model according to the current preset recovery rate. Then, input the wastewater state parameters and particle behavior characteristic parameters at the current sampling time into the selected prediction model.

[0084] S02. Based on the process characterization parameters, determine the improvement trend of the heavy metal removal effect in wastewater after extending the adsorption time after the current sampling time, and determine the effective purification cutoff time according to the improvement trend. The effective purification cutoff time is used to characterize the time when the degree of improvement in purification brought about by extending the adsorption time is reduced to the preset minimum purification requirement.

[0085] In this embodiment, the improvement trend is used to characterize the change in the additional heavy metal removal effect that can be obtained per unit extension of adsorption time when the adsorption time is extended further from the current sampling time.

[0086] Furthermore, the improvement trend is determined based on the first process characterization parameters; specifically, the improvement trend of extending the adsorption time after the current sampling time on the removal effect of heavy metals in wastewater, as involved in step S02 based on the first process characterization parameters, includes, for example: Figure 3 The steps shown are as follows:

[0087] S021. Obtain the first process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time.

[0088] In this embodiment, the first process characterization parameters include at least one of the following: the concentration of dissolved heavy metals in the wastewater at the current sampling time, the change in heavy metal concentration between adjacent sampling times, the amount of heavy metals removed per unit sampling time, and the remaining difference between the concentration of heavy metals in the wastewater at the current sampling time and the target emission concentration.

[0089] In some implementations, to improve the stability of trend judgment, step S021 obtains the first process characterization parameters corresponding to multiple consecutive sampling times, and constructs a historical data sequence of heavy metal removal of the current batch of magnetic nanomaterials in the adsorption process according to the sampling time order.

[0090] S022. Based on the current sampling time and the first process characterization parameters corresponding to at least one sampling time before the current sampling time, obtain the relationship between the concentration of heavy metals in wastewater and time.

[0091] In this embodiment, the relationship between the heavy metal concentration and time is used to characterize the change pattern of heavy metal concentration in wastewater when the current batch of magnetic nanomaterials continues to participate in adsorption.

[0092] Furthermore, the relationship of change can be constructed using the rate of change of adjacent sampling points, the trend of change of sliding time window, empirical fitting relationship or regression analysis results, and is not limited here.

[0093] For example, in a specific implementation, the heavy metal concentrations corresponding to four consecutive sampling times are 2.10 mg / L, 1.7 mg / L, 1.45 mg / L, and 1.20 mg / L, respectively. It can be seen that the overall heavy metal concentration shows a decreasing trend, and the rate of concentration decrease gradually decreases.

[0094] S023. Based on the relationship between the concentration of heavy metals in the wastewater and time, obtain the degree of improvement in purification corresponding to different extended adsorption times after the current sampling time.

[0095] In this embodiment, the increased degree of purification improvement is used to characterize the additional purification benefits brought about by continuing to extend the adsorption time relative to the current sampling time.

[0096] Furthermore, the degree of improvement in purification can be characterized by at least one of the following methods: the amount of reduction in heavy metal concentration between the current sampling time and the corresponding time after extended adsorption, the amount of new heavy metal removal corresponding to the unit extended adsorption time, the amount of increase in heavy metal removal rate, and the amount or percentage reduction of the remaining difference between the heavy metal concentration in the wastewater and the target discharge concentration at the current sampling time.

[0097] For example, at the current sampling time, the heavy metal concentration is 1.20 mg / L. If the predicted heavy metal concentrations after extending adsorption by 5 min, 10 min, and 15 min are 1.00 mg / L, 0.88 mg / L, and 0.82 mg / L, respectively, then the corresponding concentration reductions are 0.20 mg / L, 0.32 mg / L, and 0.38 mg / L, respectively; and the corresponding additional removal per unit extended adsorption time are 0.040 mg / L·min, 0.032 mg / L·min, and 0.025 mg / L·min, respectively.

[0098] S024. Determine the improvement trend based on the degree of improvement in purification corresponding to different extended adsorption times after the current sampling time.

[0099] In this embodiment, the improvement trend is the trend relationship formed by the change of the degree of improvement in purification with the extension of adsorption time: when the degree of improvement in purification corresponding to different extension adsorption times continues to decrease with the increase of adsorption time, it indicates that the new purification benefit brought by continued adsorption is in a state of decay; when the degree of improvement in purification is close to the preset minimum purification requirement, it indicates that the improvement effect of continuing to extend the adsorption time on the current target of removing remaining heavy metals has become limited.

[0100] For example, in the above embodiments, the additional removal amount per unit extended adsorption time corresponding to 5 min, 10 min, and 15 min of extended adsorption is 0.040 mg / L·min, 0.032 mg / L·min, and 0.025 mg / L·min, respectively. It can be determined that the improvement trend is a continuous downward trend. If the preset minimum purification requirement is 0.020 mg / L·min, it means that the purification benefit of continued adsorption is gradually approaching the preset minimum purification requirement.

[0101] Furthermore, the effective cutoff time for purification is determined based on the improvement trend, that is, the time when the degree of improvement in new purification is reduced to the preset minimum purification requirement, as a time boundary for judging whether continued adsorption is still necessary for purification.

[0102] S03. Based on the process characterization parameters, determine the deterioration trend of the magnetic separation implementation conditions after extending the adsorption time after the current sampling time, and determine the separation allowable cutoff time according to the deterioration trend. The separation allowable cutoff time is used to characterize the time when the degree of deterioration of the magnetic separation implementation conditions caused by extending the adsorption time reaches the preset allowable upper limit.

[0103] In this embodiment, the deterioration trend is used to characterize the change over time in terms of the increased burden of magnetic separation conditions in order to achieve a preset recovery rate for the current batch of magnetic nanomaterials when the adsorption time is extended further from the current sampling time.

[0104] Furthermore, the deterioration trend is determined based on the second process characterization parameters; specifically, step S03 involves determining the deterioration trend of the magnetic separation implementation conditions after extending the adsorption time following the current sampling time based on the second process characterization parameters, including, for example... Figure 4 The steps shown are as follows:

[0105] S031. Obtain the second process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time.

[0106] In this embodiment, the second process characterization parameters include at least one of the following: separation time required to achieve a preset recovery rate for the current batch of magnetic nanomaterials under the rated magnetic field strength of the magnetic separation system, and separation energy consumption per unit processing volume.

[0107] In some implementations, to improve the stability of the judgment of the deterioration trend, step S031 obtains the second process characterization parameters corresponding to multiple consecutive sampling times, and constructs a historical data sequence of magnetic separation implementation conditions of the current batch of magnetic nanomaterials in the adsorption process according to the sampling time sequence.

[0108] S032. Based on the current sampling time and the second process characterization parameters corresponding to at least one sampling time before the current sampling time, obtain the relationship between the magnetic separation implementation conditions and time.

[0109] In this embodiment, the relationship between the magnetic separation implementation conditions and time is used to characterize the change pattern of the magnetic separation implementation conditions required to achieve the preset recovery rate when the current batch of magnetic nanomaterials remains continuously in the adsorption system.

[0110] Furthermore, the relationship of change can be constructed using the rate of change of adjacent sampling points, the trend of change of sliding time window, empirical fitting relationship or regression analysis results, and is not limited here.

[0111] For example, if the separation times required to achieve the preset recovery rate for four consecutive sampling times are 20s, 24s, 29s, and 35s respectively, then the separation time required to achieve the same preset recovery rate gradually increases with the extension of adsorption time. Alternatively, if the separation energy consumption per unit throughput for four consecutive sampling times is 0.30kWh / t, 0.36kWh / t, 0.43kWh / t, and 0.52kWh / t respectively, then the separation energy consumption per unit throughput required to achieve the same preset recovery rate generally shows an upward trend. Therefore, it can be concluded that as the current batch of magnetic nanomaterials continues to remain in the adsorption system, the conditions for subsequent magnetic separation are gradually deteriorating.

[0112] S033. Based on the relationship between the magnetic separation implementation conditions and time, obtain the degree of new deterioration corresponding to different extended adsorption times after the current sampling time.

[0113] In this embodiment, the newly added deterioration level is used to characterize the additional magnetic separation burden required to achieve a preset recovery rate for the current batch of magnetic nanomaterials after the adsorption time is extended, relative to the current sampling time.

[0114] Furthermore, the degree of deterioration can be characterized by at least one of the following methods: the increase in magnetic field strength required to achieve the preset recovery rate between the current sampling time and the corresponding time after extended adsorption, the increase in separation time required to achieve the preset recovery rate between the current sampling time and the corresponding time after extended adsorption, and the increase in separation energy consumption per unit processing volume between the current sampling time and the corresponding time after extended adsorption.

[0115] For example, at the current sampling time, the separation time required to achieve the preset recovery rate is 35s. If it is predicted that the separation time required after extending adsorption by 5min, 10min, and 15min will be 40s, 47s, and 56s respectively, then the corresponding increases in separation time are 5s, 12s, and 21s respectively. Alternatively, at the current sampling time, the separation energy consumption per unit processing capacity is 0.52kWh / t. If it is predicted that the separation energy consumption per unit processing capacity after extending adsorption by 5min, 10min, and 15min will be 0.58kWh / t, 0.67kWh / t, and 0.79kWh / t respectively, then the corresponding increases in separation energy consumption per unit processing capacity are 0.06kWh / t, 0.15kWh / t, and 0.27kWh / t respectively.

[0116] S034. Determine the deterioration trend based on the degree of new deterioration corresponding to different extended adsorption times after the current sampling time.

[0117] In this embodiment, the deterioration trend is the trend relationship formed by the change of the degree of new deterioration with the extension of adsorption time: when the degree of new deterioration corresponding to different extension adsorption times continues to increase with the extension adsorption time, it indicates that the burden of subsequent magnetic separation implementation brought about by continued adsorption is in an upward state; when the degree of new deterioration gradually approaches the preset allowable upper limit, it indicates that the continued extension of adsorption time has approached the limit allowed by the conditions for subsequent magnetic separation implementation.

[0118] For example, in the above embodiments, the increase in separation time corresponding to the extension of adsorption by 5 min, 10 min, and 15 min is 5 s, 12 s, and 21 s, respectively. It can be determined that the deterioration trend is a continuous upward trend. If the preset allowable upper limit is that the increase in separation time does not exceed 18 s, it means that the degree of deterioration of the subsequent magnetic separation implementation conditions caused by continued adsorption is gradually approaching the preset allowable upper limit.

[0119] For example, in the above embodiments, the increase in energy consumption per unit processing capacity for adsorption extended by 5 min, 10 min, and 15 min is 0.06 kWh / t, 0.15 kWh / t, and 0.27 kWh / t, respectively. The preset allowable upper limit is that the increase in energy consumption per unit processing capacity for adsorption shall not exceed 0.20 kWh / t. This indicates that the deterioration of the subsequent magnetic separation implementation conditions caused by continued adsorption is also gradually approaching the preset allowable upper limit.

[0120] Furthermore, the separation allowable cutoff time is determined based on the deterioration trend, that is, the time corresponding to when the degree of new deterioration reaches the preset allowable upper limit is determined, as a time boundary for judging whether continued adsorption still meets the requirements of subsequent magnetic separation implementation conditions.

[0121] Specifically, the preset allowable upper limit can be set according to the design capacity of the magnetic separation device, the upper limit of the system's allowable separation time, the energy consumption control requirements per unit processing volume, and the material recycling requirements.

[0122] Furthermore, the preset allowable upper limit can be at least one of the following: the maximum allowable increase in magnetic field strength required to achieve the preset recovery rate, the maximum allowable increase in separation time, and the maximum allowable increase in separation energy consumption per unit processing volume. The specific value can be adjusted according to the wastewater treatment process conditions, the operating capacity of the magnetic separation device, and the control requirements, and is not limited here.

[0123] In this embodiment, the separation allowable cutoff time is used as the separation-side time boundary for determining whether the current batch of magnetic nanomaterials is still suitable to remain in the adsorption system. It is then used in conjunction with the purification-side time boundary to determine the critical switching time from the adsorption stage to the magnetic separation stage.

[0124] S04. Based on the earlier of the effective purification cutoff time and the permissible separation cutoff time, determine the critical switching time, and start magnetic separation when the time interval between the current sampling time and the critical switching time meets the preset start-up conditions.

[0125] In this embodiment, step S04 determines the control moment for the current batch of magnetic nanomaterials to switch from the adsorption stage to the magnetic separation stage by comprehensively considering the purification-side time boundary and the separation-side time boundary, and controls the magnetic separation to start accordingly; specifically, the earlier of the effective purification cutoff time and the permissible separation cutoff time is determined as the critical switching time.

[0126] Understandably, the critical switching moment serves as the comprehensive time boundary for the current batch of magnetic nanomaterials to switch from the adsorption stage to the magnetic separation stage, ensuring that magnetic separation is neither started too early, resulting in insufficient adsorption benefits, nor started too late, leading to excessive deterioration of subsequent magnetic separation conditions.

[0127] For example, in one specific implementation, the effective purification cutoff time corresponding to the current sampling time is 30 minutes, and the allowable separation cutoff time is 26 minutes, then 26 minutes is used as the critical switching time; as another specific implementation, the effective purification cutoff time is 22 minutes, and the allowable separation cutoff time is 28 minutes, then 22 minutes is used as the critical switching time.

[0128] Furthermore, after determining the critical switching time, it can be determined whether to initiate magnetic separation based on the time interval between the current sampling time and the critical switching time: when the time interval between the current sampling time and the critical switching time meets the preset start-up conditions, magnetic separation is initiated to reduce the impact of sampling period, control execution delay or device response lag on the switching timing.

[0129] In some specific implementations, the preset start-up condition includes one of the following: the time interval between the current sampling time and the critical switching time is less than or equal to a preset time interval threshold; or, in combination with factors such as control execution delay, valve action time, magnetic field establishment response time and sampling refresh cycle, if it is determined that continuing to maintain the adsorption state at the current sampling time will cause the actual execution time to exceed the critical switching time, the magnetic separation start-up is triggered in advance.

[0130] For example, in one specific implementation, the current sampling time is 27 minutes and the critical switching time is 30 minutes, so the time interval between the two is 3 minutes. If the preset time interval threshold is 3 minutes, then since the time interval is less than or equal to the preset time interval threshold, magnetic separation is initiated at the current sampling time.

[0131] For example, in another specific implementation, the current sampling time is 26 minutes, and the critical switching time is 30 minutes, so the time interval between the two is 4 minutes. If the total delay time corresponding to the control execution delay, valve action time, magnetic field establishment response time, and sampling refresh cycle is 4.5 minutes, which is greater than the time interval of 4 minutes, it means that if magnetic separation is not started at the current sampling time, the actual execution time of magnetic separation will be later than the critical switching time. Therefore, magnetic separation is triggered in advance at the current sampling time.

[0132] For example, if the time interval between the current sampling time and the critical switching time is 4 minutes, and the total delay time corresponding to the control execution delay, valve action time, magnetic field establishment response time and sampling refresh cycle is 2.8 minutes, which is less than the time interval of 4 minutes, it means that continuing to maintain the adsorption state will not cause the actual execution time of magnetic separation to exceed the critical switching time. Therefore, magnetic separation can be temporarily not started, and the determination can be made again at the next sampling time.

[0133] Therefore, in this embodiment, the timing of magnetic separation can be determined by combining the time interval between the current sampling time and the critical switching time, as well as factors such as control execution delay, valve action time, magnetic field establishment response time, and sampling refresh cycle, thereby improving the accuracy of magnetic separation start timing control.

[0134] In yet another embodiment, for the adsorption process of multiple batches of magnetic nanomaterials in the above-mentioned wastewater treatment process, the magnetic separation start-up is continuously controlled and optimized in a closed loop as follows:

[0135] S101. Obtain the actual magnetic separation result parameters of the previous batch of magnetic nanomaterials.

[0136] In this embodiment, the actual magnetic separation result parameter is used to characterize the actual separation and recovery rate of the previous batch of magnetic nanomaterials after magnetic separation.

[0137] S102. Based on the actual magnetic separation result parameters, correct the preset time interval threshold in the magnetic separation start-up conditions of the next batch of magnetic nanomaterials.

[0138] In this embodiment, the preset time interval threshold is the time interval threshold between the current time and the critical switching time: when the time interval between the current time and the critical switching time is less than or equal to the preset time interval threshold, magnetic separation is initiated.

[0139] In some specific embodiments, when the actual separation recovery rate obtained in step S101 is lower than the preset recovery rate, the preset time interval threshold in the magnetic separation start-up conditions of the next batch of magnetic nanomaterials is increased so that the next batch of magnetic nanomaterials meets the start-up conditions earlier.

[0140] For example, if the preset recovery rate of the previous batch of magnetic nanomaterials was 90%, but the actual separation recovery rate was 84%, it indicates that the magnetic separation initiation timing was too late. If the original preset time interval threshold was 2 minutes, then the preset time interval threshold for the next batch of magnetic nanomaterials will be adjusted to 3 minutes. Thus, when the time interval between the current moment and the critical switching moment of the next batch of magnetic nanomaterials is 2.5 minutes, the initiation conditions can be met earlier, and magnetic separation can be initiated sooner.

[0141] In some specific embodiments, when the actual separation recovery rate obtained in step S101 is higher than the preset recovery rate, the preset time interval threshold in the magnetic separation start-up conditions of the next batch of magnetic nanomaterials is reduced to delay the magnetic separation start-up timing of the next batch of magnetic nanomaterials.

[0142] For example, if the preset recovery rate of the previous batch of magnetic nanomaterials was 90%, and the actual separation recovery rate was 96%, it indicates that the magnetic separation initiation timing was relatively early. If the original preset time interval threshold was 3 minutes, then the preset time interval threshold for the next batch of magnetic nanomaterials will be adjusted to 2 minutes. Therefore, when the time interval between the current moment and the critical switching moment of the next batch of magnetic nanomaterials is 2.5 minutes, magnetic separation will not be initiated, thus appropriately delaying the magnetic separation initiation timing.

[0143] Therefore, by obtaining the actual separation and recovery rate of the previous batch of magnetic nanomaterials, and modifying the preset time interval in the magnetic separation start-up conditions of the next batch of magnetic nanomaterials according to the relationship between the actual separation and recovery rate and the preset recovery rate, the magnetic separation start-up control of multiple batches of magnetic nanomaterials can be dynamically adjusted according to the actual execution results of the previous batch, thereby forming a closed-loop optimization control under continuous operation conditions.

[0144] In yet another embodiment, based on the above-described method for adsorption and separation of magnetic nanomaterials in wastewater heavy metal treatment, the present invention also provides a magnetic nanomaterial adsorption and separation system for wastewater heavy metal treatment, comprising, as follows: Figure 5 The input unit, output unit, process characterization parameter acquisition unit, purification side boundary determination unit, separation side boundary determination unit, and magnetic separation start control unit are shown.

[0145] The input unit is connected to the adsorption reaction unit, the process characterization parameter acquisition unit is connected to the input unit, the purification side boundary determination unit and the separation side boundary determination unit are both connected to the process characterization parameter acquisition unit, the magnetic separation start control unit is connected to the purification side boundary determination unit and the separation side boundary determination unit respectively, and the output unit is connected to the magnetic separation execution unit.

[0146] Furthermore, the input unit is used to receive input data related to the adsorption process of the current batch of magnetic nanomaterials. The input data includes at least a first process characterization parameter for characterizing the removal state of heavy metals in wastewater and a second process characterization parameter for characterizing the separable state of the magnetic nanomaterials when a preset recovery rate is achieved.

[0147] The process characterization parameter acquisition unit is used to acquire the first process characterization parameter and the second process characterization parameter. The first process characterization parameter includes at least one of the following: the concentration of dissolved heavy metals in the wastewater at the current sampling time, the change in heavy metal concentration between adjacent sampling times, the amount of heavy metals removed per unit sampling time, and the remaining difference between the heavy metal concentration in the wastewater at the current sampling time and the target discharge concentration. The second process characterization parameter includes at least one of the following: the magnetic field strength required to achieve a preset recovery rate for the current batch of magnetic nanomaterials at the current sampling time, the separation time, and the separation energy consumption per unit processing volume.

[0148] The purification side boundary determination unit is used to determine the improvement trend of the heavy metal removal effect in wastewater by extending the adsorption time after the current sampling time based on the first process characterization parameters, and to determine the effective purification cutoff time according to the improvement trend.

[0149] The separation side boundary determination unit is used to determine the deterioration trend of the magnetic separation implementation conditions after extending the adsorption time after the current sampling time based on the second process characterization parameters, and to determine the separation allowable cutoff time according to the deterioration trend.

[0150] The magnetic separation start control unit is used to determine the critical switching time based on the earlier of the effective purification cutoff time and the permissible separation cutoff time, and outputs a magnetic separation start control signal to start magnetic separation when the current sampling time reaches the critical switching time or when the time interval between the current sampling time and the critical switching time meets the preset start conditions.

[0151] The output unit is used to output the magnetic separation start control signal, and / or output at least one of the following: effective purification cutoff time, permissible separation cutoff time, critical switching time, and magnetic separation start determination result.

[0152] In some specific implementations, the system further includes a second process characterization parameter prediction unit. The second process characterization parameter prediction unit is used to output the separable state prediction result of the current batch of magnetic nanomaterials when the preset recovery rate is reached, based on the wastewater state parameters and particle behavior characteristic parameters at the current sampling time, when the second process characterization parameters cannot be obtained in real time or continuously, and to use the separable state prediction result as the second process characterization parameter.

[0153] In some specific implementations, the system further includes a closed-loop optimization unit, which is used to obtain the actual magnetic separation result parameters of the previous batch of magnetic nanomaterials, and correct the preset time interval in the magnetic separation start-up conditions of the next batch of magnetic nanomaterials based on the actual magnetic separation result parameters, so as to realize continuous control and closed-loop optimization of magnetic separation start-up in the adsorption process of multiple batches of magnetic nanomaterials.

[0154] In the above embodiments, the descriptions of different embodiments have different emphases; technical features not detailed or recorded in a certain embodiment can be understood and implemented by referring to the corresponding records of other embodiments. Unless otherwise expressly stated to the contrary: technical features in each embodiment can be substituted or combined with each other without technical conflict; the order of method steps can be adjusted without affecting the function; the device / module / unit can be implemented by hardware, software or a combination thereof, and can be centralized or distributed; parameters, values ​​or ranges include reasonable errors and equivalent values, and the terms "about", "greater than / less than", "between", and range endpoints are all covered without affecting the technical effect; ordinal numbers such as "first / second" are only used for distinction and do not limit the quantity, priority or structural relationship; the reference numerals and names in the specification and drawings are only illustrative and do not limit the structural form, size ratio or installation position; improvements, substitutions or equivalent solutions that are not explicitly stated but can be obtained by those skilled in the art without creative effort should all be included in the protection scope of this invention.

Claims

1. A method for adsorption and separation of heavy metals in wastewater using magnetic nanomaterials, characterized in that, during the adsorption of heavy metals in wastewater by a batch of magnetic nanomaterials, Includes the following steps: Obtain process characterization parameters, which include at least a first process characterization parameter for characterizing the removal state of heavy metals in wastewater, and a second process characterization parameter for characterizing the separability state of magnetic nanomaterials when a preset recovery rate is achieved. Based on the process characterization parameters, the improvement trend of the removal effect of heavy metals in wastewater after extending the adsorption time after the current sampling time is determined, and the effective purification cutoff time is determined according to the improvement trend. The effective purification cutoff time is used to characterize the time when the degree of new purification improvement brought about by extending the adsorption time is reduced to the preset minimum purification requirement. Based on the process characterization parameters, the deterioration trend of the magnetic separation implementation conditions caused by extending the adsorption time after the current sampling time is determined, and the separation allowable cutoff time is determined according to the deterioration trend. The separation allowable cutoff time is used to characterize the time when the degree of deterioration of the magnetic separation implementation conditions caused by extending the adsorption time reaches the preset allowable upper limit. The critical switching time is determined based on the earlier of the effective purification cutoff time and the permissible separation cutoff time. Magnetic separation is initiated when the time interval between the current sampling time and the critical switching time meets the preset start-up conditions.

2. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 1, characterized in that, The first process characterization parameters include at least one of the following: the concentration of dissolved heavy metals in the wastewater at the current sampling time, the change in heavy metal concentration between adjacent sampling times, the amount of heavy metals removed per unit sampling time, and the residual difference between the concentration of heavy metals in the wastewater at the current sampling time and the target discharge concentration. The second process characterization parameters include at least one of the following: separation time required to achieve a preset recovery rate for the current batch of magnetic nanomaterials at the current sampling time under the rated magnetic field strength of the magnetic separation system and separation energy consumption per unit processing volume.

3. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 1, characterized in that, The second process characterization parameters are obtained through the following steps: Obtain wastewater state parameters and particle behavior characteristic parameters at the current sampling time; The wastewater state parameters and the particle behavior characteristic parameters are input into the prediction model. The prediction model is used to characterize the mapping relationship between the wastewater state parameters, the particle behavior characteristic parameters and the separable state of the magnetic nanomaterials when the preset recovery rate is reached. Based on the prediction model, the predicted result of the separable state of the magnetic nanomaterial at the current sampling time when the preset recovery rate is reached is output. The predicted results of the separable state are used as the second process characterization parameters.

4. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 3, characterized in that, The acquisition of the second process characterization parameters further includes the following steps: Based on different preset recovery rates, different prediction models are constructed. Each prediction model characterizes the mapping relationship between wastewater state parameters, particle behavior characteristic parameters and the separable state of magnetic nanomaterials at a preset recovery rate. Obtain the current preset recovery rate set in the current prediction process, select the corresponding prediction model based on the current preset recovery rate, and then input the wastewater state parameters and particle behavior characteristic parameters at the current sampling time into the selected prediction model.

5. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 1, characterized in that, The process of determining the improvement trend of heavy metal removal efficiency in wastewater by extending the adsorption time after the current sampling time based on the process characterization parameters includes the following steps: Obtain the first process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time; Based on the first process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time, the relationship between the concentration of heavy metals in wastewater and time is obtained. Based on the relationship between the concentration of heavy metals in the wastewater and time, the degree of improvement in purification corresponding to different extended adsorption times after the current sampling time is obtained. The improvement trend is determined by the degree of improvement in purification corresponding to different extended adsorption times after the current sampling time.

6. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 1, characterized in that, The determination of the deterioration trend of the magnetic separation implementation conditions after extending the adsorption time after the current sampling time based on the process characterization parameters includes the following steps: Obtain the second process characterization parameters corresponding to the current sampling time and at least one sampling time prior to the current sampling time; Based on the second process characterization parameters corresponding to the current sampling time and at least one sampling time before the current sampling time, the relationship between the magnetic separation implementation conditions and time is obtained. Based on the relationship between the magnetic separation implementation conditions and time, the degree of new deterioration corresponding to different extended adsorption times after the current sampling time is obtained; The deterioration trend is determined based on the degree of new deterioration corresponding to different extended adsorption times after the current sampling time.

7. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 1, characterized in that, The preset activation conditions include one of the following: The time interval between the current sampling time and the critical switching time is less than or equal to a preset time interval threshold. Maintaining the adsorption state at the current sampling time will cause the actual execution time to exceed the critical switching time.

8. The method for adsorption and separation of magnetic nanomaterials in wastewater heavy metal treatment according to claim 1, characterized in that, for the adsorption process of multiple consecutive batches of magnetic nanomaterials, Magnetic separation is continuously controlled in the following manner: Obtain the actual magnetic separation result parameters of the previous batch of magnetic nanomaterials; Based on the actual magnetic separation results parameters, the magnetic separation initiation conditions for the next batch of magnetic nanomaterials are adjusted.

9. The method for adsorption and separation of heavy metals in wastewater treatment using magnetic nanomaterials according to claim 8, characterized in that, The actual magnetic separation result parameter is the actual separation recovery rate. The step of correcting the magnetic separation initiation conditions for the next batch of magnetic nanomaterials based on the actual magnetic separation result parameter includes the following steps: When the actual separation recovery rate is lower than the preset recovery rate, the preset time interval threshold in the magnetic separation start-up conditions for the next batch of magnetic nanomaterials is increased. When the actual separation recovery rate is higher than the preset recovery rate, the preset time interval threshold in the magnetic separation start-up conditions for the next batch of magnetic nanomaterials is reduced.

10. A magnetic nanomaterial adsorption and separation system for heavy metal treatment in wastewater, characterized in that, include: A process characterization parameter acquisition unit is used to acquire process characterization parameters, which include at least a first process characterization parameter for characterizing the removal state of heavy metals in wastewater, and a second process characterization parameter for characterizing the separable state of magnetic nanomaterials when a preset recovery rate is achieved. The purification side boundary determination unit is used to determine the improvement trend of the removal effect of heavy metals in wastewater by extending the adsorption time after the current sampling time based on the process characterization parameters, and to determine the effective purification cutoff time according to the improvement trend. The effective purification cutoff time is used to characterize the time when the degree of new purification improvement brought about by extending the adsorption time is reduced to the preset minimum purification requirement. The separation side boundary determination unit is used to determine the deterioration trend of the magnetic separation implementation conditions after the current sampling time by extending the adsorption time based on the process characterization parameters, and to determine the separation allowable cutoff time according to the deterioration trend. The separation allowable cutoff time is used to characterize the time when the degree of deterioration of the magnetic separation implementation conditions caused by extending the adsorption time reaches the preset allowable upper limit. The magnetic separation start control unit is used to determine the critical switching time based on the earlier of the effective purification cutoff time and the permissible separation cutoff time, and to start magnetic separation when the time interval between the current sampling time and the critical switching time meets the preset start conditions.

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