Method, equipment and system for filtering and purifying comprehensive wastewater

Abstract

The invention relates to the technical field of sewage treatment, in particular to a comprehensive wastewater filtering and purifying method, equipment and system. The method comprises the following steps: obtaining pretreated wastewater through pretreatment operation; precipitating through a flocculating agent to obtain wastewater subjected to primary treatment; carrying out activated sludge process and mud-water separation to obtain wastewater subjected to secondary treatment; in activated sludge process treatment, an aeration tank is divided into regions, and temperature, salinity and dissolved oxygen are collected; determining an influence weight based on a discrete condition of correlation of temperature, salinity and dissolved oxygen; determining a comprehensive influence weight based on the time difference, the influence weight and the fluctuation condition, and adjusting an aeration threshold value based on the comprehensive influence weight to complete the activated sludge process; standing the wastewater subjected to secondary treatment through a buffer pool, and filtering to complete purification of the wastewater. The wastewater treatment precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a filtering and purifying method, device and system for comprehensive wastewater. BACKGROUND

[0002] With the rapid development of industrialization and urbanization, water pollution problems are becoming increasingly serious. Generally, wastewater is generated by human production and life or industrial products. If the substances in wastewater can be recycled or separated, economic benefits can be generated. Wastewater refers to water containing waste. Pollutants in wastewater are useful substances discharged by humans and mixed into water, which makes the water unusable and discarded, becoming wastewater. Therefore, the pollutants in wastewater are generally useful substances, and most of the wastewater is generated by industrial production. Filtering and purifying comprehensive wastewater generated in the industrial field, which contains organic pollutants, inorganic pollutants, and possible heavy metals, microorganisms, and other complex components, and further recycling the treated water source is an important research direction for water resource protection and recycling at present.

[0003] At present, the filtering and purifying process of comprehensive wastewater generated in the industrial field mainly includes pretreatment and three-stage treatment. In the pretreatment stage, coarse and fine grid filtration, sand settling tank, and adjusting tank treatment are needed to protect subsequent equipment and balance water quality. The first-stage treatment mainly performs flocculation and sedimentation in a sedimentation tank. The second-stage treatment mainly degrades dissolved organic matter through active sludge method and two-sedimentation-tank treatment. The third-stage treatment mainly performs filtration and backwashing through a V-type filter for deep treatment. After completing the pretreatment and three-stage treatment process, the treated water source is discharged, and the sludge generated in the process is treated. In the operation process of comprehensive wastewater, when the active sludge method is used in the second-stage treatment, the dissolved oxygen is maintained by oxygenating the wastewater through an aeration device in the aeration tank to make the aerobic microorganisms degrade organic matter. However, the oxygen is affected by factors such as temperature and salinity during the entire dissolution process. The traditional control method cannot respond in time and effectively when the temperature and salinity fluctuate, which affects the control of dissolved oxygen in the aeration tank and leads to poor filtering and purifying effect of comprehensive wastewater. SUMMARY

[0004] In order to solve the technical problem of poor purifying effect caused by poor control of dissolved oxygen in the second-stage treatment, the present application provides a filtering and purifying method, device and system for comprehensive wastewater, and the technical solution is as follows: In a first aspect, the present application provides a filtering and purifying method for comprehensive wastewater, which comprises the following steps: Preliminarily filtering industrial wastewater through a grid, precipitating the wastewater after preliminary filtration through a sand settling tank, and adjusting the pH value to obtain pretreated wastewater; The pretreated wastewater is transported to a sedimentation tank, a flocculating agent is added for flocculation and sedimentation, and the wastewater remaining after sedimentation is used as the first-stage treated wastewater; The first-stage treated wastewater is sent to an aeration tank, treated by the activated sludge method in the aeration tank, and the treated mixed liquor is sent to a secondary sedimentation tank for separation of sludge and water to obtain the second-stage treated wastewater; In the process of treatment by the activated sludge method, the following steps are included: S1, the aeration tank is divided into several regions according to distance, and the influencing factors and dissolved oxygen at each time in each region are collected, the influencing factors including temperature and salinity; S2, a preset sliding window is set for each time, and the influence weight of each type of influencing factor at each time is determined based on the dispersion of the correlation between the influencing factors and the dissolved oxygen at each time in each sliding window; S3, the comprehensive influence weight is obtained based on the difference between adjacent times, the fluctuation and the influence weight of each type of influencing factor; the preset initial factor and the comprehensive influence weight are combined to adjust the preset fuzzification subset; the dissolved oxygen in each region, the preset dissolved oxygen set value and the adjusted fuzzification subset are used as the input of the fuzzy PID control, and then the preset aeration threshold is adjusted, and the activated sludge method treatment is completed based on the adjusted aeration threshold; The second-stage treated wastewater is transported into a buffer tank and allowed to stand, and the purification operation of the wastewater is completed by a filter tank after standing In the above scheme, in the process of comprehensive wastewater filtration and purification treatment, the influence of the stability of the dissolved oxygen in the aeration tank on the decomposition of organic matter by aerobic microorganisms is considered to be large, which affects the wastewater treatment effect, therefore, the influence of the temperature and salinity fluctuations in the aeration tank on the dissolved oxygen in the wastewater in the aeration tank is analyzed, which leads to the inability to accurately control the dissolved oxygen in the aeration tank, the temperature and salinity in the treatment process are collected, and the correlation between the temperature and salinity and the dissolved oxygen is obtained by analyzing the influence of the temperature and salinity fluctuations on the dissolved oxygen, and the correlation is weighted by the stability of the correlation, and a dynamic scaling factor is constructed by combining the influence of the temperature and salinity on the dissolved oxygen, and the fuzzification subset of the fuzzy PID control is dynamically adjusted, which improves the fine adjustment and convergence speed of the fuzzy PID control, and further improves the wastewater treatment precision.

[0005] In one embodiment, in the pretreatment process, the used coarse grid has a grid gap of 10-20 mm; and the used fine grid has a grid gap of 2-5 mm.

[0006] In one embodiment, in the primary treatment process, the mixing reaction time of the flocculant is 10-20 minutes; the flocculation and sedimentation time is 40-60 minutes.

[0007] In one embodiment, in the secondary treatment process, the wastewater treated by the activated sludge method is delivered to the secondary sedimentation tank for sludge-water separation, wherein the surface load is 0.6-1.2 m³ / (m²×h); the sedimentation time in the secondary sedimentation tank is 2-4 hours.

[0008] In one embodiment, the method for determining the influence weight of each type of influence factor at each time point based on the dispersion of the correlation between each influence factor and dissolved oxygen in each sliding window at each time point is as follows: Each time point and a preset number of time points before the time point form a sliding window; The correlation coefficient of all element values of each type of environmental factor in the sliding window at each time point and all dissolved oxygen is calculated as the correlation coefficient of each type of environmental factor at each time point; the variation coefficient of the correlation coefficient of each type of influence factor at each time point in the sliding window is calculated. The reliability weight of each type of influence factor is determined based on the variation coefficient of each type of influence factor; The product of the reliability weight and the correlation coefficient of each type of influence factor at each time point is taken as the influence weight of each type of influence factor.

[0009] In one embodiment, the reliability weight is positively correlated with the variation coefficient of each type of influence factor.

[0010] In one embodiment, the comprehensive influence weight is positively correlated with the difference between adjacent time points of all types of influence factors and the influence weight, and is negatively correlated with the fluctuation of the influence factor.

[0011] In one embodiment, the method for treating the wastewater after the secondary treatment is as follows: The wastewater after the secondary treatment is discharged through the overflow weir and delivered to the buffer tank through the effluent pipeline; in this process, the flow rate of the wastewater is 0.5-1.0 m / s; then the wastewater is statically placed for 15-30 minutes to balance the water quality fluctuation; after the static placement, the wastewater is filtered through the filter tank.

[0012] In a second aspect, the application further provides a filtration and purification system for comprehensive wastewater, which comprises a pretreatment module, a primary treatment module, a secondary treatment module, and a tertiary treatment module, to realize the steps of the filtration and purification method for comprehensive wastewater.

[0013] In a third aspect, the embodiments of the present application further provide a filtering and purifying device for comprehensive wastewater, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the steps of the filtering and purifying method for comprehensive wastewater according to any one of the above embodiments when executing the computer program.

[0014] The present application has the following beneficial effects: In the process of filtering and purifying the comprehensive wastewater, the present application considers that the stability of dissolved oxygen in the aeration tank has a great influence on the effect of organic matter decomposition by aerobic microorganisms, and thus affects the wastewater treatment effect. Therefore, based on the analysis of the interference of dissolved oxygen stability, the present application analyzes the influence of temperature and salinity fluctuations in the aeration tank on the dissolved oxygen in the wastewater, which leads to the inability to accurately control the dissolved oxygen in the aeration tank. The temperature and salinity in the treatment process are collected. Considering that the increase or decrease of temperature and salinity will inhibit or promote the correlation characteristics of dissolved oxygen to different degrees, the present application analyzes the influence of temperature and salinity fluctuations on the dissolved oxygen, respectively obtains the correlation degree of temperature and salinity under mutual interference and dissolved oxygen, and weights the stability of the correlation degree. The dynamic scaling factor is constructed by combining the influence of temperature and salinity on dissolved oxygen, and the fuzzy subset of fuzzy PID control is dynamically adjusted, which improves the fine tuning and convergence speed of fuzzy PID control, and further improves the wastewater treatment precision. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0016] Figure 1 A filtering and purifying method for comprehensive wastewater provided by an embodiment of the present application is shown in the flow chart. Figure 2 A flow chart of the control method in the activated sludge process. DETAILED DESCRIPTION

[0017] In order to further clarify the technical means and effects taken by the present application to achieve the predetermined object of the application, the following describes in detail the specific implementation, structure, features and effects of a comprehensive wastewater filtration and purification method, device and system according to the present application, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0019] A comprehensive wastewater filtration and purification method, device and system embodiment: The specific scheme of a comprehensive wastewater filtration and purification method, device and system provided by the present application is described in detail below in combination with the accompanying drawings.

[0020] Please refer to Figure 1 which shows a comprehensive wastewater filtration and purification method flowchart provided by one embodiment of the present application, which includes the following steps: Step S001: obtaining pretreated wastewater by pretreatment operation.

[0021] First, the wastewater is pretreated.

[0022] The industrial wastewater used in factory processing is first filtered by a grid. A coarse grid with a grid gap of 10-20 mm is placed outside the drain at an angle of 30-45° to intercept branches, plastic bottles, cloth and other large-volume floating objects, protecting the subsequent equipment from damage. Then a fine grid with a grid gap of 2-5 mm is placed outside the coarse grid to further filter smaller suspended impurities such as food residue and hair.

[0023] The filtered wastewater is discharged into a sand settling tank for 30-60 seconds of static sedimentation to remove inorganic particles with a higher specific gravity (such as sand, coal cinder, etc.), preventing these substances from wearing out the pump and pipeline. The settled wastewater is discharged into a conditioning tank, a dosing device is used to dose the wastewater tank, and a stirring device (mechanical stirring or air stirring) is used to stir and adjust the pH value of the wastewater, adjusting the pH value of the wastewater to 6-8, close to neutral, to meet the subsequent treatment. The conditioning tank balances the water quality (such as pH, concentration) and water quantity fluctuations of the wastewater, avoiding the impact on the subsequent treatment unit, thus obtaining pretreated wastewater.

[0024] Preferably, in the present embodiment, the grid gap of the coarse grid is 15 mm and the grid gap of the fine grid is 3 mm; the wastewater after preliminary filtration is statically settled in the sand settling tank for 60 s, and the wastewater is adjusted to a pH value of 7.

[0025] At this point, the pretreated wastewater is obtained.

[0026] In step S002, the wastewater after the first-stage treatment is obtained by flocculant precipitation.

[0027] The pretreated wastewater is subjected to the first-stage treatment.

[0028] The pretreated wastewater in the conditioning tank is pumped to the sedimentation tank, and flocculation and precipitation are performed on the wastewater by adding flocculants. The optimal dosage of the flocculants is obtained through laboratory experiments, and the water quality is detected in real time by using a pH detector, a turbidity detector, and a COD online detection instrument. The frequency and dosage of the flocculant dosing pump are controlled by PID, and the flocculants are mixed for 10-20 minutes and precipitated for 40-60 minutes, thereby obtaining the wastewater after the first-stage treatment.

[0029] Preferably, in the present embodiment, the flocculant relaxation time is 15 minutes, and the precipitation time is 60 minutes.

[0030] At this point, the wastewater after the first-stage treatment is obtained.

[0031] In step S003, the wastewater after the first-stage treatment is sent to the aeration tank, and the wastewater is treated by the activated sludge method in the aeration tank. The mixed liquid after the treatment is sent to the secondary sedimentation tank for sludge-water separation to obtain the wastewater after the second-stage treatment.

[0032] The wastewater after the first-stage treatment is treated by the activated sludge method and sludge-water separation to obtain the wastewater after the second-stage treatment.

[0033] The wastewater after the first-stage treatment in the sedimentation tank is pumped to the aeration tank, mixed with the activated sludge returned from the aeration tank and the secondary sedimentation tank, and oxygen is provided by the aeration device to maintain the dissolved oxygen required for microbial metabolism. At the same time, stirring ensures that the sludge and wastewater are in sufficient contact, thereby treating the wastewater by the activated sludge method. The aeration tank is provided with sufficient dissolved oxygen by the oxygen supply system aeration blower or a special aerator.

[0034] After activated sludge treatment, the treated mixed liquor is transported from the aeration tank into the secondary sedimentation tank for sludge-water separation operation, with the surface load controlled at 0.6-1.2 m³ / (m²×h) and the sedimentation time controlled at 2-4 hours. A sludge scraper is provided in the secondary sedimentation tank to concentrate the settled sludge into the bottom sludge hopper, while the supernatant is discharged through the overflow weir, and the sludge at the bottom of the secondary sedimentation tank is returned to the aeration tank through a sludge return pump (the flow rate is designed according to the return ratio of 50%-100%) to maintain the sludge concentration in the aeration tank at 3000-5000 mg / L. The remaining sludge is gradually transported to the thickening tank, and the sludge in the thickening tank is allowed to stand for 12-24 hours for sedimentation treatment, followed by dewatering treatment of the sludge by a belt filter, and the treated sludge is incinerated, landfilled or used for composting. The supernatant after the secondary sedimentation tank treatment is the wastewater after secondary treatment.

[0035] The treatment process of the activated sludge method is as shown in Figure 2

[0036] S1, the aeration tank is divided into several regions according to the distance, and the temperature, salinity and dissolved oxygen at each time point in each region are collected.

[0037] In the process of treating the wastewater after primary treatment, the content of dissolved oxygen is a key factor to ensure the activity of microorganisms, treatment efficiency and sludge properties, and it is usually necessary to control the content of dissolved oxygen to remain stable, while the dissolved oxygen (DO) is affected by factors such as temperature and salinity. Therefore, the aeration tank is divided into N regions at equal intervals from the inlet end to the outlet end, and online DO monitors are used at the center of each region to collect the temperature, salinity and dissolved oxygen in the aeration tank in real time. The value of N can be adjusted according to the specific circumstances of the implementer; in this embodiment, N is valued at 10, and data is obtained every 2 seconds. The corresponding data of the past week is obtained as comparative analysis data. Each kind of monitoring data obtained in each region is subjected to abnormal value detection using local outlier factor LOF, and the influence of abnormal values is excluded.

[0038] Thus, the temperature, salinity and dissolved oxygen at each time point are obtained.

[0039] S2, the influence weight is determined based on the dispersion of the correlation between temperature, salinity and dissolved oxygen.

[0040] ​Generally, the wastewater after primary treatment enters the inlet end of the aeration tank, and the organic matter in the wastewater is decomposed by the aerobic microorganisms in the aeration tank, and finally the wastewater after decomposition of the organic matter flows out from the outlet end of the aeration tank. In this process, the wastewater in the aeration tank shows a trend of gradually decreasing organic matter concentration from the inlet end to the outlet end. When the aerobic microorganisms decompose the organic matter through metabolic activity, a large amount of dissolved oxygen is consumed, so the region with a higher content of organic matter consumes more dissolved oxygen, showing a trend of gradually increasing dissolved oxygen content from the inlet end to the outlet end. Therefore, when providing dissolved oxygen for wastewater aeration, a gradually decreasing aeration method is usually used, that is, the gas supply at the inlet is relatively large, and the gas supply near the outlet is gradually reduced, so that the oxygen supply and the oxygen demand of the mixed liquid are kept in dynamic balance. The control area of the gradually decreasing aeration method is divided into N areas of the aeration tank, and the aeration threshold is set from high to low according to the distance from the inlet end.

[0041] When oxygen is transported to the wastewater in the aeration tank by the gradually decreasing aeration method, the dissolved oxygen content of the wastewater is affected by temperature, salinity and other conditions. The real-time metabolism of the aerobic microorganisms in the wastewater consumes dissolved oxygen, and the change of environmental temperature causes a certain degree of fluctuation in the temperature of the wastewater. In the plug flow aeration tank, as the wastewater before reaction continuously flows into the aeration tank, and the wastewater after reaction continuously flows out, the inorganic salt content in the aeration tank also continuously changes.

[0042] The temperature and salinity in the local area of the aeration tank also change in real time with time, and these influencing factors will have a certain impact on the dissolved oxygen in the local area of the aeration tank when they fluctuate. For each area, a sliding window with a length of k is constructed for each time and a preset number of times before it.

[0043] Considering that the dissolved oxygen is affected by temperature and salinity, the increase of temperature and salinity will inhibit the dissolved oxygen. In actual conditions, the influence of different temperatures and salinities on the dissolved oxygen may offset or accumulate, resulting in different correlation degrees between temperature and salinity and dissolved oxygen when they change at different times. Therefore, all temperatures in the sliding window corresponding to the current time are taken as a sequence, and similarly, all salinities and dissolved oxygen in the sliding window corresponding to the current time are taken as corresponding sequences; they are respectively denoted as temperature sequence, salinity sequence and dissolved oxygen sequence; the correlation coefficients of the sequences of temperature and dissolved oxygen, and the sequences of salinity and dissolved oxygen at the current time are calculated respectively, which are used to represent the correlation degree between the temperature, salinity and dissolved oxygen at the current time. In this embodiment, the correlation coefficient is obtained by calculating the Pearson correlation coefficient.

[0044] If the influencing factor and the dissolved oxygen have a large fluctuation in the correlation degree within a sliding window, the influence of the influencing factor on the dissolved oxygen is more unstable, and the correlation degree of the influencing factor on the dissolved oxygen at the moment is less reliable. For each time of the sliding window, the correlation coefficients of all times in the sliding window are calculated, and all the correlation coefficients of temperature, salinity and dissolved oxygen are respectively constructed into a sequence as the correlation sequence of each time.

[0045] The variation coefficient of all elements in the correlation sequence of temperature and dissolved oxygen is denoted as a first variation coefficient, and the variation coefficient of all elements in the correlation sequence of salinity and dissolved oxygen is denoted as a second variation coefficient; the greater the first variation coefficient and the second variation coefficient are, the greater the fluctuation range of the correlation of the two is, and the less reliable the correlation analysis of the two is.

[0046] Therefore, the reliability weight of temperature is obtained based on the first variation coefficient, and the reliability weight of salinity is obtained based on the second variation coefficient.

[0047] The reliability weight of temperature is positively correlated with the first variation coefficient, and the reliability weight of salinity is negatively correlated with the second variation coefficient.

[0048] It should be noted that the positive correlation means that when one variable increases, the other variable also increases, the two variables have the same change direction, and when one variable changes from large to small or from small to large, the other variable also changes from large to small or from small to large; the specific relationship is determined by actual application, and the present application does not make special limitation.

[0049] It should be noted that the negative correlation means that when one variable increases, the other variable decreases, the two variables have opposite change directions, and when one variable changes from large to small or from small to large, the other variable also changes from small to large or from large to small; the specific relationship is determined by actual application, and the present application does not make special limitation.

[0050] Preferably, in the present embodiment, , , denotes the first variation coefficient, denotes the second variation coefficient, denotes a normalization function, denotes the reliability weight of temperature, denotes the reliability weight of salinity.

[0051] Then, the product of the reliability weight of temperature and the correlation coefficient of temperature is taken as the influence weight of temperature, and the product of the reliability weight of salinity and the correlation coefficient of salinity is taken as the influence weight of salinity.

[0052] Then, the product of the credibility weight of temperature and salinity and the correlation coefficient of temperature and salinity is taken as the influence weight of temperature and salinity, respectively.

[0053] If temperature and salinity are negatively correlated with dissolved oxygen at the corresponding time, temperature and salinity have a hindering effect on dissolved oxygen, and when the credibility of temperature and salinity is high, the correlation between temperature and salinity and dissolved oxygen is relatively stable, and at this time, temperature and salinity present a stable inhibitory effect on the concentration of dissolved oxygen.

[0054] Thus, the influence weight of temperature and the influence weight of salinity at each time are obtained.

[0055] S3, based on the time difference, the influence weight and the fluctuation to determine the comprehensive influence weight, based on which the activated sludge method is adjusted to complete the aeration threshold.

[0056] Considering that when the two influence factors fluctuate, they will affect the correlation with dissolved oxygen, and there will be mutual inhibition or accumulation between the two influence factors, therefore, in order to represent the comprehensive influence of the two influence factors on dissolved oxygen, the comprehensive influence weight is obtained based on the difference between adjacent times of each type of influence factor, the fluctuation and the influence weight.

[0057] The comprehensive influence weight is positively correlated with the difference between adjacent times of all kinds of influence factors, the influence weight, and negatively correlated with the fluctuation of the influence factor.

[0058] Preferably, in the embodiment, the expression of the comprehensive influence weight is: , The difference between the temperature at the tth time and the temperature at the (t-1)th time is represented by The standard deviation of the temperature difference of all times in the sliding window is represented by The influence weight of temperature at the tth time is represented by The difference between the salinity at the tth time and the salinity at the (t-1)th time is represented by The standard deviation of the salinity difference of all times in the sliding window is represented by The influence weight of salinity at the tth time is represented by The comprehensive influence weight at the tth time is represented by The linear normalization function is represented by

[0059] When the temperature is negatively correlated at the tth moment and the temperature decreases, the temperature at the tth moment has a promoting effect on the solubility. Similarly, when the salinity is negatively correlated at the tth moment and the salinity decreases, the salinity at the tth moment also has a promoting effect on the solubility. The cumulative comprehensive influence is obtained by addition, and the greater the comprehensive influence weight is; when the two influence factors simultaneously have an inhibitory effect, the comprehensive influence after addition increases, and the comprehensive influence weight is greater; otherwise, when one of the two influence factors has an inhibitory effect and the other has a promoting effect, the comprehensive influence after addition decreases, and the comprehensive influence weight is smaller.

[0060] The initial weight is set, and the sum of the initial weight and the comprehensive influence weight is used as a dynamic scaling factor for instruction control. By representing the influence degree of temperature and salinity on dissolved oxygen, when temperature and salinity fluctuate greatly, the comprehensive influence weight of temperature and salinity increases, and more oxygen supply is needed, and the dynamic scaling factor increases accordingly.

[0061] The dynamic scaling factor can reflect the difference between the case where temperature and salinity fluctuate greatly in the same direction and the case where temperature and salinity are stable, and a fuzzy subset is preset; in this embodiment, the domain of the fuzzy PID control algorithm is initialized as , and thus the fuzzy subset is ; the dynamic scaling factor at each moment is multiplied by each element in the fuzzy subset to obtain a real-time adjustment fuzzy subset, so as to realize dynamic adjustment of the fuzzy subset, that is, when temperature and salinity are severely transformed, a larger control value is used to realize rapid change of the oxygen supply of the aeration equipment, and a smaller control value is used to maintain stability under the condition that the temperature and salinity are not affected. The dissolved oxygen set value set in each region, the dissolved oxygen at the current moment, and the real-time adjustment fuzzy subset are used as inputs of the fuzzy PID control algorithm, and three control components are output by the algorithm. The control components are delivered to the corresponding aeration equipment, and the aeration threshold is controlled based on the control components. The fuzzy PID control is a known technology, and will not be described in detail here.

[0062] After the aeration threshold is controlled, the activated sludge method is processed based on the aeration threshold.

[0063] At this point, the wastewater after secondary treatment is obtained.

[0064] In step S004, the wastewater after secondary treatment is filtered after being placed in a buffer tank to complete the purification of the wastewater.

[0065] The wastewater separated by the secondary sedimentation tank is subjected to three-stage treatment, the supernatant of the secondary sedimentation tank is discharged through the overflow weir and is transported to the buffer tank through the effluent pipeline, the flow rate needs to be controlled at 0.5-1.0 m / s to prevent disturbing the settled sludge, and the residence time is 15-30 minutes to balance the water quality fluctuation. The raw water after standing is transferred to the V-shaped filter tank for deep filtration and purification of the wastewater, the raw water is uniformly fed into the filter tank through the V-shaped tank, and is subjected to suspended solids interception operation by passing through the quartz sand filter material layer from top to bottom, the filtered wastewater is transported to the clear water tank from the bottom filter head, and the filtered clear water of the clear water tank is used for backwashing operation of the equipment. The filtration and purification operation of the comprehensive wastewater is finally completed.

[0066] At this point, the filtration and purification of the wastewater are completed.

[0067] Based on the same inventive concept as the above method, the embodiments of the present application also provide a filtration and purification system for comprehensive wastewater, which comprises a pretreatment module, a first-stage treatment module, a second-stage treatment module and a third-stage treatment module; and is used to realize the steps of the filtration and purification method for comprehensive wastewater.

[0068] Based on the same inventive concept as the above method, the embodiments of the present application also provide a filtration and purification device for comprehensive wastewater, which comprises a memory, a processor and a computer program stored in the memory and running on the processor, and the processor realizes the steps of any one of the above-mentioned filtration and purification methods for comprehensive wastewater when executing the computer program.

[0069] It should be noted that the above-mentioned embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

[0070] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts of each of the embodiments can be referred to each other, and each of the embodiments mainly describes the differences from other embodiments.

Claims

1. A comprehensive wastewater filtration and purification method, characterized in that, The method includes the following steps: Industrial wastewater is initially filtered through a screen, and the pre-filtered wastewater is then settled in a grit chamber and the pH value is adjusted to obtain pre-treated wastewater. The pretreated wastewater is transported to a sedimentation tank, where flocculants are added for flocculation and sedimentation. The remaining wastewater after sedimentation is used as the primary treated wastewater. The primary treated wastewater is sent to an aeration tank, where it is treated using the activated sludge process. The treated mixture is then sent to a secondary sedimentation tank for sludge-water separation to obtain secondary treated wastewater. The treatment process using the activated sludge method includes the following steps: S1. Divide the aeration tank into several areas according to distance, and collect the influencing factors and dissolved oxygen in each area at each time. The influencing factors include temperature and salinity. S2, a sliding window is preset for each time point, and the influence weight of each type of influencing factor at each time point is determined based on the discreteness of the correlation between the influencing factors and dissolved oxygen at each time point within each sliding window. S3, based on the time difference between adjacent moments, fluctuations and influence weights of each type of influencing factor, obtain the comprehensive influence weight; after combining the preset initial factor and the comprehensive influence weight, adjust the preset fuzzy subset; use the dissolved oxygen, preset dissolved oxygen setpoint and adjusted fuzzy subset of each region as inputs for fuzzy PID control, and then adjust the preset aeration threshold, and complete the activated sludge process based on the adjusted aeration threshold. The secondary treated wastewater is transported to a buffer tank and allowed to settle. After settling, the wastewater is then purified by passing it through a filtration tank.

2. The comprehensive wastewater filtration and purification method as described in claim 1, characterized in that, During the pretreatment process, the coarse grid used has a mesh size of 10–20 mm; the fine grid used has a mesh size of 2–5 mm.

3. The comprehensive wastewater filtration and purification method as described in claim 1, characterized in that, In the primary treatment process, the mixing reaction time of the flocculant is 10-20 minutes; the flocculation and sedimentation time is 40-60 minutes.

4. The comprehensive wastewater filtration and purification method as described in claim 1, characterized in that, In the secondary treatment process, the wastewater treated by the activated sludge method is transported to the secondary sedimentation tank for sludge-water separation, where the surface loading rate is 0.6 to 1.2 m³ / (m²×h); the sedimentation time in the secondary sedimentation tank is 2 to 4 hours.

5. The comprehensive wastewater filtration and purification method as described in claim 1, characterized in that, The method for determining the influence weight of each type of influencing factor at each time point based on the discreteness of the correlation between influencing factors and dissolved oxygen at each time point within each sliding window is as follows: A sliding window is formed by each time point and a preset number of time points preceding it. Calculate the correlation coefficients between all element values ​​of each type of environmental factor and all dissolved oxygen within the sliding window at each time point as the correlation coefficients of each type of environmental factor at each time point; calculate the coefficient of variation of the correlation coefficients of each type of influencing factor within the sliding window at each time point. The credibility weight of each type of influencing factor is determined based on the coefficient of variation of each type of influencing factor. The product of the credibility weight and the correlation coefficient of each type of influencing factor at each time point is used as the influence weight of each type of influencing factor.

6. The comprehensive wastewater filtration and purification method as described in claim 5, characterized in that, The credibility weights are positively correlated with the coefficients of variation of each type of influencing factor.

7. The comprehensive wastewater filtration and purification method as described in claim 1, characterized in that, The overall influence weight is positively correlated with the time difference and influence weight of all types of influencing factors, and negatively correlated with the fluctuation of influencing factors.

8. The comprehensive wastewater filtration and purification method as described in claim 1, characterized in that, The method for treating wastewater after secondary treatment is as follows: The secondary treated wastewater is discharged through an overflow weir and transported to a buffer tank via an outlet pipe; during this process, the wastewater flow rate is 0.5–1.0 m / s; then it is allowed to stand for 15–30 minutes to equalize water quality fluctuations; after standing, it is filtered through a filtration tank.

9. A comprehensive wastewater filtration and purification system, comprising a pretreatment module, a primary treatment module, a secondary treatment module, and a tertiary treatment module, characterized in that, Wastewater filtration is performed in different modules using different steps to achieve the steps of a comprehensive wastewater filtration and purification method as described in any one of claims 1-8.

10. A comprehensive wastewater filtration and purification device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the comprehensive wastewater filtration and purification method as described in any one of claims 1-8.

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