Automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment

Abstract

The application discloses an automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment, and belongs to the technical field of industrial wastewater treatment and automatic control. In view of the problem that the existing process relies on manual experience and the oxidation and flocculation stages are improperly connected, the multifunctional modified material containing dithiocarbamate salt groups, quinone groups and pre-complexed manganese and zinc ions is prepared first; the material and hydrogen peroxide are synchronously added in the acid oxidation stage, and the control system monitors the redox potential change rate in real time; when the redox potential reaches the preset threshold value and the characteristic change point with the first derivative of zero or the change from positive to negative appears and is maintained for the preset maintenance time, the system is automatically adjusted to be alkaline, the modified material triggers the net capture and chelation crosslinking reaction, and finally solid-liquid separation is carried out; the polymer skeleton is protected from indiscriminate attack of free radicals, the problem of drug antagonism is overcome, and the stable and up-to-standard effluent quality is realized.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment and automation control technology, specifically an automatic control method for oxidation flocculation parameters in manganese zinc wastewater treatment. Background Technology

[0002] Current methods for controlling manganese-zinc wastewater treatment parameters largely rely on manual operation experience and static, fixed-time process arrangements, lacking real-time evaluation and system modeling of the dynamic oxidation and flocculation processes in terms of data dimensions. Although some solutions attempt to automate the process using basic programmable logic controllers or perform logic control based on a single set threshold, they generally suffer from low accuracy in acquiring reaction endpoint characteristic data and insufficient intelligence in multi-dimensional parameter linkage regulation. This traditional control method ignores the logical dependence between the real-time reaction state of the wastewater and the chemical response point of the modified materials, and lacks a dynamic adjustment mechanism when facing fluctuations in actual complex water quality components, which can easily lead to improper connection between the oxidation and flocculation stages, excessive reagent consumption, and low overall treatment efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide an automatic control method for oxidation and flocculation parameters in manganese-zinc wastewater treatment. This method aims to improve upon existing technologies where wastewater treatment parameter control relies heavily on manual experience and static, fixed-time processes, lacking a dynamic adjustment mechanism driven by multi-dimensional online monitoring data. This results in improper transitions between oxidation and flocculation stages, low accuracy in identifying reaction endpoints, and difficulty adapting to complex water quality fluctuations. Specifically, the technical solution of this invention is as follows:

[0004] An automatic control method for oxidation flocculation parameters in manganese-zinc wastewater treatment includes the following steps: S1, preparation of multifunctional modified materials: preparation of materials with polyacrylamide as the backbone, containing dithiocarbamate groups, quinone groups, and pre-complexed components. as well as Ionic polymers, as multifunctional modified materials;

[0005] S2. Wastewater Information Collection: Wastewater containing mancozeb is introduced into the reaction tank. A control system is used to collect the initial pH value, redox potential value, turbidity and heavy metal ion concentration of the wastewater through online monitoring instruments. The control system is also connected to an acid pump, a hydrogen peroxide solution metering pump, a multi-functional modified material dosing pump and an alkali pump.

[0006] S3. Oxidation stage parameter control: The pH value of the wastewater in the reaction tank is adjusted to be acidic by the control system. Hydrogen peroxide solution and the multifunctional modified material obtained in step S1 are added to the reaction tank, and the reaction is stirred. The control system collects the oxidation-reduction potential value in real time according to the preset sampling cycle.

[0007] S4. Parameter control of chelation and flocculation stage: When the control system detects that the redox potential value in the reaction tank reaches the preset threshold, and the redox potential change curve obtained by the control system according to the preset sampling period shows a characteristic change point where the first derivative is zero or changes from positive to negative and is maintained for a preset maintenance time, the control system adjusts the pH value in the reaction tank to be alkaline, generating precipitated sludge.

[0008] S5. Solid-liquid separation: The mixture after step S4 is subjected to solid-liquid separation, and the supernatant and precipitated sludge are collected.

[0009] The beneficial effects of this invention are as follows: During the oxidation stage, the polymer skeleton and quinone structure of the multifunctional modified material remain intact, and the electron transfer mediated by the quinone group effectively protects the polymer carbon chain from non-selective oxidative degradation by free radicals; the conformational change of the reagent and the pH / redox potential threshold set by the programmable logic controller are precisely synchronized, avoiding the phenomenon of excessive or insufficient dosing in traditional processes, effectively improving the removal efficiency of pollutants, and achieving stable compliance of effluent quality; the reagent is synthesized using ethylenediamine, carbon disulfide, and a solution containing manganese and zinc ions, and the resulting chelated flocculent sludge has a stable structure, effectively reducing the burden of subsequent treatment of hazardous waste. Detailed Implementation

[0010] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0011] Example 1:

[0012] This embodiment provides an automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment, and the specific operation is as follows;

[0013] S1. Preparation of multifunctional modified materials

[0014] Take 100 kg of solid powdered nonionic polyacrylamide with a molecular weight of 8-10 million, add 1000 L of deionized water as solvent and stir to dissolve. Then add 50 kg of ethylenediamine at a mass ratio of 1:0.5. Adjust the pH of the system to 8.2 with a 20% sodium hydroxide solution. After keeping the temperature at 60℃ for 20 min, raise the temperature to 90℃ and react for 3 h to obtain an aminated polyacrylamide intermediate.

[0015] The system containing the above-mentioned aminated polyacrylamide intermediate was cooled to 50°C, and 5 kg of p-benzoquinone was added at 5% of the mass of polyacrylamide. The mixture was stirred for 2 hours, so that some of the primary amine sites on the aminated polyacrylamide intermediate were connected to the carbon-carbon double bond on the p-benzoquinone ring through Michael addition reaction to form CN single bond, thereby grafting the quinone group onto the polymer backbone.

[0016] The intermediate system grafted with p-benzoquinone was cooled to 30°C, and 63.3 kg of carbon disulfide was added dropwise at a molar ratio of carbon disulfide to ethylenediamine of 1:1. At the same time, a 20% sodium hydroxide solution was added to maintain the pH of the reaction solution at 9.0, which caused the dithiocarbamate reaction to occur, generating a polymer containing dithiocarbamate groups.

[0017] Add 50 L of a mixed solution containing manganese sulfate and zinc sulfate to a polymer system containing dithiocarbamate groups, wherein Mn² + and The total concentration was 1.2 g / L, Mn² + and The mass ratio was 1:1, the pH was adjusted to 6.5, and the mixture was stirred at 35℃ for 1 hour to complete the pre-complexation, resulting in a brownish-yellow homogeneous viscous liquid.

[0018] In this preparation method, the amount of ethylenediamine introduced in the above-mentioned limited ratio retains the bridging ability of the polyacrylamide main chain, and the amount of p-benzoquinone grafted in the limited ratio controls the self-oxidation side reaction of the material, which is suitable for wastewater systems with high turbidity and high heavy metal concentration.

[0019] S2, Wastewater Information Collection Stage

[0020] The treatment target was a combined wastewater containing mother liquor from the co-production of mancozeb, oxadixyl, and methomyl. The influent flow rate was 1.0 m³, the initial pH was 6.4, the initial redox potential was +128 mV, the turbidity was 1680 NTU, and the Mn²⁺ content was [not specified in the original text]. + The concentration is 96 mg / L. The concentration was 83 mg / L, and the COD was 5120 mg / L. The control system adopted a programmable logic controller and was connected to an online pH meter, a redox potential electrode, a turbidity meter, and an online heavy metal analyzer. It was also connected to an acid pump, a hydrogen peroxide solution metering pump, a multi-functional modified material dosing pump, and an alkali pump. The control system received 4-20mA signals from the online pH meter and the redox potential electrode, controlled the frequency conversion output of the acid pump and the alkali pump, and collected the initial data of the above wastewater at the beginning of the treatment.

[0021] S3, Oxidation Stage Parameter Control

[0022] The control system adds hydrochloric acid to the reaction tank as an acid solution. The programmable logic controller gradually increases the frequency of the acid pump from 20Hz to 35Hz according to the feedback signal from the pH meter, so as to adjust the wastewater to acidic conditions, specifically the pH value is adjusted to 3.0 and maintained at this value for 8 minutes.

[0023] After the pH value stabilizes, add a 30% hydrogen peroxide solution and the multifunctional modified material prepared by S1 and maintain the stirring speed at 220 rpm. At this time, the quinone group and the pre-complexed manganese zinc site in the multifunctional modified material participate in the decomposition of hydrogen peroxide solution, promote the chain scission of recalcitrant pesticide organic matter, and the dithiocarbamate group remains in a limited exposure state under acidic conditions, reducing the consumption of pesticides caused by premature flocculation in the oxidation stage.

[0024] Furthermore, the polymer chain is in a relatively contracted state, which can reduce the mass transfer obstacle caused by premature entrapment during the oxidation stage; the programmable logic controller continuously records the changes in redox potential and calculates the rate of change of redox potential at adjacent moments according to a sampling period of 10 seconds.

[0025] When the redox potential reaches the preset threshold +450mV, the stability assessment timer is started; after the first derivative of the redox potential reaches zero at the threshold, the timer is maintained for 5 minutes. If the redox potential fluctuation does not exceed ±8mV during this period, the oxidation phase is considered to have ended.

[0026] S4, Parameter Control of Chelation and Flocculation Stage

[0027] After the above judgment conditions are met, the system switches to alkaline conditions. The control system adjusts the pH value in the reaction tank back to 8.0. The alkaline solution is a 20% sodium hydroxide solution. The programmable logic controller starts the alkali pump according to the redox potential judgment result and sets the pump frequency to 32Hz according to the pH meter feedback until the pH reaches 8.0. The adjustment time is controlled to 6 minutes.

[0028] When the pH value rises to 8.0, the dithiocarbamate groups in the multifunctional modified material dissociate and become exposed, and Mn² + and It rapidly participates in chelation precipitation, while the polymer bridging effect is enhanced, forming macroscopically visible flocs and precipitating with some degradation fragments; after settling for 30 minutes, the supernatant enters the subsequent biological treatment stage, and the sludge is collected by plate and frame filter press; this method allows the oxidation stage and the flocculation stage to be completed continuously in the same system, avoiding reaction deviations caused by inconsistent timing of manual switching.

[0029] Example 2:

[0030] This embodiment provides an automatic control method for oxidation flocculation parameters in manganese zinc wastewater treatment, which specifically includes the following steps;

[0031] S1. Preparation of multifunctional modified materials

[0032] Take 100 kg of solid powdered nonionic polyacrylamide with a molecular weight of 8-10 million, add 1000 L of deionized water as solvent and stir to dissolve. Then add 120 kg of ethylenediamine, with a mass ratio of 1:1.2. Adjust the pH of the system to 8.5 with 20% sodium hydroxide solution, heat to 95 °C and react for 3.5 h to obtain an aminated polyacrylamide intermediate.

[0033] After cooling the system containing the above-mentioned aminated polyacrylamide intermediate to 50°C, 10 kg of p-benzoquinone was added at 10% of the mass of polyacrylamide, and the mixture was stirred for 2.5 h. The intermediate system grafted with p-benzoquinone was then cooled to 33°C, and 182.4 kg of carbon disulfide was added dropwise at a molar ratio of carbon disulfide to ethylenediamine of 1:1.2, while a 20% sodium hydroxide solution was added simultaneously to induce a dithiocarbamate reaction.

[0034] Add 80 L of a mixed solution of manganese sulfate and zinc sulfate to a polymer system containing dithiocarbamate groups, wherein Mn²⁺ + and The total concentration was 1.5 g / L, Mn² + and The mass ratio is 1.2:1. The pH value is adjusted to 6.8, and the mixture is stirred at 35℃ for 1.5h to complete the pre-complexation. Under this ratio, the number of amino groups, quinone groups and dithiocarbamate groups in the material is relatively balanced, and the oxidation catalytic ability and heavy metal chelation ability are well matched, making it suitable for continuous and stable operation.

[0035] S2, Wastewater Information Collection Stage

[0036] The equipment configuration and control logic of Example 1 are used; 1.0 m³ of wastewater is treated, with an initial pH of 6.8, an initial oxidation-reduction potential of +146 mV, a turbidity of 1520 NTU, and Mn²⁺. + The concentration is 71 mg / L. The concentration was 66 mg / L and the COD was 4680 mg / L; the initial data was collected by the control system.

[0037] S3, Oxidation Stage Parameter Control

[0038] The control system adjusts the pH of the wastewater to 3.5; at this value, the consumption rate of hydrogen peroxide solution and catalytic activity are relatively balanced, which is beneficial to reducing the corrosion burden on the equipment; 6.8 mL / L of hydrogen peroxide solution and 2.5 g / L of the multifunctional modified material prepared by S1 are added; the preset threshold of oxidation-reduction potential is set to +500 mV; when the oxidation-reduction potential reaches +500 mV and the first derivative changes from positive to negative and remains so for 7 minutes, the oxidation stage is considered to be over; this set of parameters is suitable for co-line production wastewater with moderate concentrations of organic matter and heavy metals, and the oxidation stage is more balanced.

[0039] S4, Parameter Control of Chelation and Flocculation Stage

[0040] After the oxidation stage is completed, the control system adjusts the pH value in the reaction tank back to 8.5. Under this alkaline condition, the chelation precipitation of manganese and zinc and the compactness of flocs have a synergistic effect, which increases the settling speed of the generated flocs and reduces the turbidity of the supernatant. After completion, sedimentation and collection are carried out.

[0041] Example 3:

[0042] This embodiment provides an automatic control method for oxidation flocculation parameters in manganese zinc wastewater treatment, which specifically includes the following steps;

[0043] S1. Preparation of multifunctional modified materials

[0044] Take 100 kg of solid powdered nonionic polyacrylamide with a molecular weight of 8-10 million, add 1000 L of deionized water as solvent and stir to dissolve. Then add 200 kg of ethylenediamine at a mass ratio of 1:2. Heat to 100 °C at pH 8.8 and react for 4 h. Cool to 50 °C and add 15 kg of p-benzoquinone, stir for 3 h. Then cool to 35 °C and add carbon disulfide dropwise at a molar ratio of carbon disulfide to ethylenediamine of 1:1.5, while simultaneously adding sodium hydroxide solution. React for 2.5 h.

[0045] Add 100L of a mixed solution of manganese sulfate and zinc sulfate, wherein Mn² + and The total concentration was 1.8 g / L, Mn² + and The mass ratio is 1:1.5, the pH value is adjusted to 7.0, and the mixture is stirred at 35°C for 2 hours. This ratio increases the number of reactive amine groups and the density of dithiocarbamate groups, making it suitable for conditions with strict requirements for the removal of heavy metals at the end of the process.

[0046] S2, Wastewater Information Collection Stage

[0047] The equipment configuration and control logic of Example 1 are used; 1.0 m³ of wastewater is treated, with an initial pH of 7.1, an initial oxidation-reduction potential of +162 mV, a turbidity of 1390 NTU, and Mn²⁺.+ The concentration is 58 mg / L. The concentration was 54 mg / L and the COD was 4210 mg / L; the initial data was collected by the control system.

[0048] S3, Oxidation Stage Parameter Control

[0049] The control system adjusts the pH of the wastewater to 4.0; at this value, acid consumption is low, which is suitable for wastewater with high raw water buffer salt content; 6.0 mL / L of hydrogen peroxide solution and 2.2 g / L of the multifunctional modified material prepared by S1 are added; the preset threshold of oxidation-reduction potential is set to +550 mV; when the oxidation-reduction potential reaches +550 mV and the first derivative is zero and remains so for 10 min, the oxidation stage is considered to have ended; this parameter prolongs the residence time of the oxidation stage and enhances the stability of the determination of the oxidation endpoint;

[0050] S4, Parameter Control of Chelation and Flocculation Stage

[0051] After the oxidation phase is completed, the control system will adjust the pH value in the reaction tank back to 9.0. This value is conducive to the full exposure and chelation of high-density dithiocarbamate groups with manganese and zinc ions, which is suitable for operating conditions with strict control of heavy metal concentration in the effluent. The filtrate is clarified after the sludge is pressed and filtered.

[0052] Comparative Example 1:

[0053] The difference between this comparative example and Example 2 is that the multifunctional modified material obtained in step S1 is not used. Hydrogen peroxide solution is added only under acidic conditions, and unmodified polyacrylamide flocculant is added after oxidation. The specific operation is as follows: the pH value of the wastewater is adjusted to 3.5, 6.8 mL / L of hydrogen peroxide solution is added, and the mixture is stirred for 30 min; then the pH value is adjusted to 8.5, 2.5 g / L of unmodified polyacrylamide is added, and the mixture is allowed to settle for 30 min. In this comparative example, the oxidant and flocculant act in steps, and no quinone catalytic site is formed to coordinate with the dithiocarbamate group. The removal of heavy metals mainly relies on hydroxide sedimentation and physical bridging, and the sludge volume is relatively large. Other wastewater quality, equipment configuration, and programmable logic controller control system are exactly the same as in Example 2.

[0054] Comparative Example 2:

[0055] The difference between this comparative example and Example 2 is that: in step S4, the first derivative of the redox potential change curve is not used for determination; instead, a fixed reaction time of 25 minutes is used as the end condition for the oxidation stage, and the pH value is adjusted from 3.5 to 8.5 after the fixed time is reached; in this comparative example, the multifunctional modified material still has oxidation and chelation functions, but the oxidation endpoint does not correspond to the actual reaction state of the wastewater, and when the raw water fluctuates, the residual hydrogen peroxide solution is prone to be too high or the organic matter is not sufficiently destroyed; other wastewater quality, multifunctional modified material formulation, hydrogen peroxide solution dosage, and programmable logic controller are exactly the same as in Example 2.

[0056] Performance Testing and Datasheets

[0057] To verify the treatment effects of Examples 1 to 3 and Comparative Examples 1 and 2, three parallel experiments were conducted on each group of samples, and the average values ​​were compared. The test standards were as follows: COD was determined according to HJ828, Mn and Zn were determined by atomic absorption spectrophotometry, turbidity was determined according to GB / T13200, sludge volume was measured by standing a 1L graduated cylinder for 30 minutes, and TCLP leaching was performed according to HJ / T300. The test procedure was as follows: 1.0 m³ of integrated wastewater was treated according to the specific steps of each example and comparative example. After solid-liquid separation, the supernatant was collected to measure COD, Mn, Zn and turbidity, and the filter press sludge was collected to measure the sludge volume and TCLP leaching concentration after 30 minutes. The specific test results are shown in Table 1.

[0058] Table 1 Comparison of performance test results of each embodiment and comparative example.

[0059]

[0060] As can be seen from the data of Examples 1 to 3 in the table, all three methods showed high COD removal rate and heavy metal removal rate, and the sludge volume was lower than that of Comparative Example 1 and Comparative Example 2.

[0061] The fact that no multifunctional modified material was used in Comparative Example 1 indicates that when hydrogen peroxide solution and unmodified polyacrylamide are used alone, there is a lack of chemical response coordination between oxidation and flocculation, resulting in high effluent turbidity and sludge volume.

[0062] Although multifunctional modified materials were used in Comparative Example 2, the redox potential threshold and the maximum point of the first derivative were not used for determination. This indicates that fixed-time switching will weaken the correspondence between automatic parameter control and material response, resulting in the inability to accurately control according to the actual situation of the raw water.

[0063] Example 2 showed a high COD removal rate in this group of experiments, while Example 3 performed well in terms of heavy metal removal rate and sludge stability, indicating that different parameter values ​​can be adapted to different wastewater compositions. In summary, the combination of multifunctional modified materials and the linkage control of oxidation-reduction potential and pH meter is the main reason for achieving stable treatment results.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any conventional modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for automatic control of oxidation flocculation parameters in the treatment of wastewater from mancozeb, characterized by, Includes the following steps: S1. Preparation of multifunctional modified materials: Preparation of materials with polyacrylamide as the backbone, containing dithiocarbamate groups, quinone groups, and pre-complexed compounds. as well as Ionic polymers, as multifunctional modified materials; S2. Wastewater Information Collection: Wastewater containing mancozeb is introduced into the reaction tank. A control system is used to collect the initial pH value, redox potential value, turbidity and heavy metal ion concentration of the wastewater through online monitoring instruments. The control system is also connected to an acid pump, a hydrogen peroxide solution metering pump, a multi-functional modified material dosing pump and an alkali pump. S3. Oxidation stage parameter control: The pH value of the wastewater in the reaction tank is adjusted to be acidic by the control system. Hydrogen peroxide solution and the multifunctional modified material obtained in step S1 are added to the reaction tank, and the reaction is stirred. The control system collects the oxidation-reduction potential value in real time according to the preset sampling cycle. S4. Parameter control of chelation and flocculation stage: When the control system detects that the redox potential value in the reaction tank reaches the preset threshold, and the redox potential change curve obtained by the control system according to the preset sampling period shows a characteristic change point where the first derivative is zero or changes from positive to negative and is maintained for a preset maintenance time, the control system adjusts the pH value in the reaction tank to be alkaline, generating precipitated sludge. S5. Solid-liquid separation: The mixture after step S4 is subjected to solid-liquid separation, and the supernatant and precipitated sludge are collected.

2. The automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment according to claim 1, characterized in that, In step S1, the specific preparation steps of the multifunctional modified material include: (1) Mix polyacrylamide and ethylenediamine at a mass ratio of 1:0.5-1:2, adjust the pH of the system to 8.2-8.8, keep warm at 60-65℃ for 20-30 minutes, and then raise the temperature to 90-100℃ to carry out the transamidation temperature-controlled reaction to obtain the aminated polyacrylamide intermediate. (2) Cool the system to 50°C and add p-benzoquinone at 5-15% of the mass of polyacrylamide. Stir the reaction to allow the quinone group to be grafted onto the polymer backbone. (3) Cool the system to 30-35℃, add carbon disulfide dropwise according to the molar ratio of carbon disulfide to ethylenediamine of 1:1-1:1.5, and add sodium hydroxide solution dropwise to produce dithiocarbamate reaction, generating polymer containing dithiocarbamate groups; (4) Add a solution containing manganese sulfate and zinc sulfate, adjust the pH value to 6.5-7.0, and stir at a constant temperature for 1-2 hours to carry out pre-complexation, thereby obtaining the multifunctional modified material.

3. The automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment according to claim 1, characterized in that, In step S3, the control system adjusts the pH value of the wastewater in the reaction tank to 3.0-4.

0.

4. The automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment according to claim 1, characterized in that, In step S4, the preset threshold is +450mV to +550mV.

5. The automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment according to claim 4, characterized in that, In step S4, the preset duration is 5-10 minutes.

6. The automatic control method for oxidation flocculation parameters in manganese zinc wastewater treatment according to claim 1, characterized in that, In step S4, the control system adjusts the pH value in the reaction tank to 8.0-9.

0.

7. The automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment according to claim 1, characterized in that, The control system is a programmable logic controller (PLC); in step S3, the PLC automatically controls the acid pump to add acid solution to the reaction tank to adjust the pH value of the wastewater; in step S4, the PLC automatically controls the alkali pump to add alkali solution to the reaction tank to adjust the pH value of the wastewater.

8. The automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment according to claim 1, characterized in that, In step S4, after the control system adjusts the pH value in the reaction tank to be alkaline, the dithiocarbamate groups on the multifunctional modified material undergo a trapping and cross-linking reaction with the heavy metal ions in the wastewater to generate the precipitated sludge.

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