Control method and control system of high-pH raw water purification system

Abstract

The invention provides a control method and a control system for a high-pH raw water purification system. The control method comprises the following steps: acquiring and presetting a first deviation relation curve, a CO2 average deviation coefficient, a second deviation relation curve, a third deviation relation curve and a coagulant average deviation coefficient; monitoring the pH value of each water inlet and the turbidity and Al < 3 + > concentration of the water outlet of the coagulative precipitation tank in real time; the CO2 real-time corrected aeration amount and the coagulant real-time corrected addition amount are obtained; and finally, according to the real-time corrected aeration quantity of CO2 and the real-time corrected addition quantity of the coagulant, controlling the aeration quantity of CO2 in the aeration type activated carbon filter tank and the aeration membrane filter tank, the aeration quantity of CO2 in the coagulative precipitation tank and the addition quantity of the coagulant. According to the invention, through refined CO2 automatic addition control, the coagulating sedimentation effect is effectively improved, and the concentration of aluminum ions in water is reduced, so that the service life of a membrane is prolonged, and effective operation of the whole water purification process is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of water purification technology, and in particular to a control method and a control system for a high pH raw water purification system. Background Art

[0002] In response to the problem of high aluminum concentration in the water discharged from the factory due to high pH of raw water, the main response methods currently adopted by domestic water plants are to add acidified coagulants, increase the dosage of coagulants, or directly add acid to the raw water to reduce the pH. However, the above methods all have disadvantages: the use of acidified coagulants and increasing the dosage of coagulants will increase production costs, the residual aluminum in the effluent is difficult to control, there is still a risk of exceeding the standard, and the frequent switching of coagulants is not conducive to the stable operation of the water plant process; the acidification of raw water requires the construction of a new acidification system, which requires large engineering investment, and strong acids are corrosive, posing safety hazards.

[0003] In the water purification process, usually the downstream of the coagulation device involves a variety of membrane treatment processes, and the high concentration of aluminum ions in the water caused by the high pH of the raw water will penetrate the membrane components in the subsequent process, causing membrane damage and membrane pollution. Therefore, in order to avoid aluminum ions penetrating the membrane components in the subsequent water purification process and causing membrane damage and membrane pollution, it is necessary to adjust the pH of the raw water; adding CO2 to adjust the pH value of the raw water is one of the methods.

[0004] In the prior art, there are reports on how to add CO2 to efficiently and accurately control the coagulation and precipitation effect and the aluminum ion concentration. The invention patent application with application publication number CN104649473A discloses a device and method for controlling the residual aluminum concentration in the high pH raw water treatment process. This method adds carbon dioxide to the high pH raw water to regulate the pH of the water body, avoiding the corrosion caused by the addition of liquid strong acids such as sulfuric acid and hydrochloric acid to the water plant production equipment and the pollution of the raw water; through mixing with aluminum sulfate coagulant, aluminum is precipitated and filtered out as hydroxide, which is purer and more environmentally friendly.

[0005] However, the above method is for ordinary reservoir raw water, which has better water quality and is easier to achieve precise control of CO2. In the actual urban water supply system, in order to ensure sufficient urban water supply, reservoir raw water is often only a part of the water supply source, and it needs to be supplemented by water sources such as wetlands and lakes. For wetland and lake water sources, the turbidity of raw water and the metabolites produced by microorganisms and plants in them are relatively high. These substances will interfere with the precise control of CO2, making it impossible to achieve more precise CO2 control.

[0006] Therefore, it is necessary to provide a high pH raw water purification control system and control method, which can promote the coagulation and sedimentation effect and reduce the aluminum ion concentration by achieving more precise CO2 addition control, avoid damage to various membrane materials in subsequent processes, and thus promote the effective operation of the entire water purification process. Summary of the invention

[0007] The present invention provides a control method and control system for a high pH raw water purification system. The control method refines the CO2 addition control, can effectively improve the coagulation and sedimentation effect, and reduce the concentration of aluminum ions in the water body, thereby promoting the effective operation of the entire water purification system.

[0008] The specific technical solutions are as follows:

[0009] The present invention provides a control method for a high pH raw water purification system, wherein the high pH raw water purification system comprises a coagulation sedimentation tank, an aerated activated carbon filter tank, an aerated membrane filter tank, and an automatic control system;

[0010] Control methods include:

[0011] S1: Set the following data information in the automation control system:

[0012] 1) The first deviation relationship curve between pH value and CO2 aeration amount;

[0013] 2) CO2 average deviation coefficient;

[0014] 3) The second deviation relationship curve between turbidity and the amount of coagulant added;

[0015] 4) Average coefficient of deviation of coagulant;

[0016] S2: Real-time monitoring of the pH value at the inlet of the coagulation sedimentation tank, the pH value at the inlet of the aerated activated carbon filter, the pH value at the inlet of the aerated membrane filter, and the turbidity at the outlet of the coagulation sedimentation tank;

[0017] S3: Retrieve the real-time pH value data of S2, calculate the real-time deviation aeration volume of CO2 in each pool according to the first deviation relationship curve, and then calculate the real-time corrected aeration volume of CO2 according to the internal CO2 average deviation coefficient;

[0018] S4: Retrieve the real-time turbidity data of S2, calculate the real-time deviation addition amount of the coagulant according to the second deviation relationship curve, and then calculate the real-time correction addition amount of the coagulant in the coagulation sedimentation tank according to the internal coagulant average deviation coefficient;

[0019] S5: According to the real-time correction of the aeration volume of CO2 and the real-time correction of the addition volume of coagulant, the dosage of CO2 in the aeration activated carbon filter and the aeration membrane filter, as well as the dosage of CO2 and the dosage of coagulant in the coagulation sedimentation tank are controlled.

[0020] The present invention firstly sets CO2 aeration ports in the coagulation sedimentation tank, the aerated activated carbon filter tank and the aerated membrane filter tank respectively, so as to realize the precise control of CO2 aeration in steps; and corrects the CO2 aeration amount in each tank and the addition amount of coagulant in the coagulation sedimentation tank by setting the deviation coefficient; thereby achieving efficient purification of raw water while reducing CO2 aeration and coagulant addition.

[0021] Further, in S1, the method for obtaining the first deviation relationship curve is: using high pH raw water as simulated water sample I, taking simulated water sample I, exposing CO2 gas thereto, measuring the changes in pH value and CO2 aeration amount, and establishing a first deviation relationship curve between pH value and CO2 aeration amount;

[0022] The method for obtaining the second deviation relationship curve is: take a simulated water sample I, add an aluminum salt coagulant thereto, measure the changes in turbidity and the amount of coagulant added, and establish a second deviation relationship curve between turbidity and the amount of coagulant added.

[0023] Furthermore, in S1, the method for obtaining the CO2 average deviation coefficient is:

[0024] According to formula (1), the average deviation coefficient of CO2 is calculated;

[0025]

[0026] in, It represents the average deviation coefficient of CO2; i represents the value of the change of pH value in the simulated water sample I, i is from high to low, the initial value of i is the initial pH value of the simulated water sample I, generally 7 to 8, n is the lowest value after the pH value drops, generally 5 to 6; N represents the number of times the pH and its corresponding CO2 deviation aeration volume are measured during the process of pH dropping from i to n; Q di represents the CO2 deviation aeration volume when the pH value is i, which is obtained through the first deviation relationship curve; Q ti represents the theoretical aeration rate of CO2 when the pH value is i, which is obtained through the first theoretical relationship curve;

[0027] The first theoretical relationship curve is obtained by using the qualified effluent treated by the high pH raw water purification system as simulated water sample II, taking simulated water sample II, exposing it to CO2 gas, measuring the changes in pH value and CO2 aeration amount, and establishing the first theoretical relationship curve between pH value and CO2 aeration amount.

[0028] Furthermore, in S1, the method for obtaining the average deviation coefficient of the coagulant is:

[0029] According to formula (2), the average deviation coefficient of coagulant is calculated;

[0030]

[0031] Among them, δ PAC represents the average deviation coefficient of the coagulant; j represents the value of the turbidity change in the simulated water sample II, j is from high to low, the initial value of j is the initial turbidity value of the simulated water sample II, generally 20-25, m is the lowest value after the turbidity decreases, generally 1-2; M represents the number of times the turbidity and its corresponding coagulant dosage are measured in the process of the turbidity decreasing from j to m; D dj represents the deviation dosage of coagulant when the turbidity is j, which is obtained through the second deviation relationship curve; D tj It represents the theoretical dosage of coagulant when the turbidity is j, which is obtained through the second theoretical relationship curve;

[0032] The second theoretical relationship curve is obtained by taking a simulated water sample II, adding an aluminum salt coagulant thereto, measuring the changes in turbidity and the amount of coagulant added, and establishing a second theoretical relationship curve between turbidity and the amount of coagulant added.

[0033] Furthermore, the water quality of the simulated water sample I is: pH 7.6-8.8; permanganate index 2.4-4.8 mg / L; ammonia nitrogen 0.1-0.6 mg / L; turbidity 12-25 NTU; the water quality of the simulated water sample II is: pH 6.5-7.5; permanganate index 1.0-2.5 mg / L; ammonia nitrogen 0.04-0.1 mg / L; turbidity 0-0.2 NTU.

[0034] Further, in S3, the calculation formula of CO2 real-time corrected aeration volume is: CO2 real-time corrected aeration volume = CO2 real-time deviation aeration volume × CO2 deviation coefficient;

[0035] Furthermore, in S4, the calculation formula of the real-time correction addition amount of coagulant is: real-time correction addition amount of coagulant = real-time deviation addition amount of coagulant × average deviation coefficient of coagulant.

[0036] Furthermore, the control method further includes: S6: real-time monitoring of the Al at the outlet of the aerated activated carbon filter. 3+ Concentration, if Al 3+ When the concentration is 0.05-0.20 mg / L, the effluent from the aerated activated carbon filter will be returned to the coagulation sedimentation tank.

[0037] The present invention also provides a high pH raw water purification system, comprising a coagulation sedimentation tank, an aerated activated carbon filter tank, an aerated membrane filter tank and an automatic control system; the automatic control system executes the steps of the control method described above.

[0038] Furthermore, the automatic control system includes: water quality online monitoring equipment, CO2 dosing equipment, coagulant dosing equipment and feedback control system;

[0039] The water quality online monitoring equipment is equipped with water quality monitoring probes installed at the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank, the outlet of the aerated activated carbon filter tank and the outlet of the aerated membrane filter tank;

[0040] The CO2 dosing equipment is provided with CO2 aeration ports respectively connected with the coagulation sedimentation tank, the aerated activated carbon filter tank and the aerated membrane filter tank;

[0041] The coagulant dosing device is provided with a coagulant dosing port connected to the coagulation sedimentation tank;

[0042] The feedback control system executes the steps of the control method as described above.

[0043] Furthermore, the feedback control system comprises: an information collection module, a data processing and analysis module and a feedback control module;

[0044] An information collection module is used to receive water quality data information from a water quality monitoring probe and feed the water quality data information back to a data processing and analysis module;

[0045] The data processing and analysis module receives the data information from the information acquisition module, calculates and corrects the CO2 aeration amount and the coagulant addition amount;

[0046] Feedback control module, including CO2 addition control submodule and coagulant addition control submodule;

[0047] The CO2 dosing control submodule receives data information from the data processing and analysis module to control the opening and closing of the CO2 aeration port and the gas flow rate;

[0048] The coagulant addition control submodule controls the opening and closing of the coagulant addition port and the coagulant addition flow rate.

[0049] Furthermore, the feedback control system also includes a sampling monitoring module for collecting the inlet and outlet water of the water purification system, detecting and obtaining data information of the first deviation relationship curve, the CO2 average deviation coefficient, the second deviation relationship curve and the coagulant average deviation coefficient, and transmitting the data information to the data processing and analysis module.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The present invention effectively improves the effect of coagulation and sedimentation through refined automatic CO2 addition control, and reduces the concentration of aluminum ions in the water body, thereby extending the membrane life and promoting the effective operation of the entire water purification process.

[0052] (2) Improve coagulation efficiency: By precisely controlling CO2 addition and optimizing pH value, the coagulation efficiency of aluminum salt coagulant is significantly improved, the floc formation time is reduced, and the processing speed is increased.

[0053] (3) Reduce the amount of coagulant used: Under optimized pH conditions, the amount of aluminum salt coagulant used is reduced, which reduces operating costs and reduces the potential environmental impact of aluminum salt coagulants.

[0054] (4) Reduce the use of chemical additives: Using CO2 to replace traditional acidification coagulants or directly adding acid reduces the use of chemical additives, environmental pollution and operational risks.

[0055] (5) Improve water quality safety: By reducing the aluminum concentration in the water leaving the factory, the water quality safety is improved to meet more stringent drinking water standards and health requirements.

[0056] (6) The solution of the present invention has good operational simplicity, system stability and scalability, is suitable for water plants of different sizes, and is easy to integrate with other water treatment processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the mechanism of an embodiment of a high pH raw water purification control system of the present invention;

[0058] Among them, 1. Coagulation sedimentation tank; 2. Aerated activated carbon filter; 3. Aerated membrane filter tank; 4. Automatic control system; 41. Water quality online monitoring equipment; 42. CO2 dosing equipment; 43. Coagulant dosing equipment; 44. Feedback control system.

[0059] Figure 2 A structural block diagram of an embodiment of the feedback control system of the present invention;

[0060] Among them, 44 is a feedback control system; 441 is an information acquisition module; 442 is a data processing and analysis module; 443 is a feedback control module.

[0061] Figure 3 It is a schematic diagram of the overall structure of the device part of the high pH raw water purification control system of the present invention;

[0062] Figure 4 It is a top view of the overall structure of the device part of the high pH raw water purification control system of the present invention;

[0063] Markings in the figure: 1. Coagulation sedimentation tank; 11. First connecting pipe; 12. First tank body; 121. Separation block; 122. Mixing area; 123. Sedimentation area; 124. Water passage; 125. Guide surface; 126. Sedimentation frame; 127. Filter screen; 13. Coagulant delivery pipe; 131. Delivery hole; 132. One-way valve; 14. Coagulant metering pump; 15. Coagulant storage tank; 2. Aerated activated carbon filter; 20. Second connecting pipe group; 21. Second tank body; 22. Mounting platform; 23. Support plate; 231. Through hole ; 232. Oxygen aeration pipe; 234. Oxygen storage tank; 24. Activated carbon layer; 3. Aeration membrane filter tank; 31. Third tank body; 32. Membrane assembly; 7. CO2 dosing equipment; 71. Carbon dioxide storage tank; 72. Exhaust pipe; 73. Carbon dioxide metering pump; 74. Dosing main pipe; 75. Carbon dioxide aeration pipe; 5. Water inlet pipe; 6. Water outlet pipe; 8. Water quality online monitoring equipment; 81. First water quality monitoring probe; 82. Second water quality monitoring probe; 83. Third water quality monitoring probe; 84. Fourth water quality monitoring probe.

[0064] Figure 5 It is a schematic flow chart of an embodiment of a high pH raw water purification system control method of the present invention. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the specific implementation of the high pH raw water purification control system and control method is described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0066] The high pH raw water described in this application, i.e., simulated water sample I, refers to raw water with "pH of 7.6-8.8; permanganate index of 2.4-4.8 mg / L; ammonia nitrogen of 0.1-0.6 mg / L; turbidity of 12-25 NTU", which is generally derived from wetland water, lake water, river water, etc. The control system and method provided by the present invention can effectively reduce the CO2 dosage in the high pH raw water treatment process, thereby achieving cost savings and energy consumption control.

[0067] The present invention provides an example of a high pH raw water purification system, specifically as follows Figure 1 As shown. The high pH raw water purification system of the present invention is mainly composed of a coagulation sedimentation tank 1, an aerated activated carbon filter tank 2 and an aerated membrane filter tank 3 connected in sequence and an automatic control system 4. The automatic control system 4 is composed of a water quality online monitoring device 41, a CO2 dosing device 42, a coagulant dosing device 43 and a feedback control system 44. The automatic control can adopt a PLC control system or a DCS control system.

[0068] like Figure 2As shown, the feedback control system 44 provided by the present invention specifically includes: an information acquisition module 441, a data processing and analysis module 442 and a feedback control module 443; the information acquisition module is used to receive water quality data information from the water quality monitoring probe, and feed back the water quality data information to the data processing and analysis module; the data processing and analysis module receives the data information from the information acquisition module, calculates and corrects the CO2 aeration amount and the coagulant addition amount; the feedback control module includes a CO2 addition control submodule and a coagulant addition control submodule; the CO2 addition control submodule receives the data information from the data processing and analysis module, and controls the opening and closing of the CO2 aeration port and the gas flow rate; the coagulant addition control submodule controls the opening and closing of the coagulant addition port and the coagulant addition flow rate.

[0069] The present invention also provides a specific structure of a high pH raw water purification system device, such as Figures 3-4 The structural part of the high pH raw water purification system device includes a coagulation sedimentation tank 1, an inlet pipe 5 arranged at one end of the coagulation sedimentation tank 1, a first connecting pipe 11 arranged at the other end of the coagulation sedimentation tank 1, an aerated activated carbon filter 2 connected to the coagulation sedimentation tank 1 through the first connecting pipe 11, a second connecting pipe group 20 arranged on the aerated activated carbon filter 2, an aerated membrane filter 3 connected to the aerated activated carbon filter 2 through the second connecting pipe group 20, a CO2 dosing device 7 connected to the aerated activated carbon filter 2 and the aerated membrane filter 3, and an outlet pipe 6 arranged on the aerated membrane filter 3.

[0070] Specifically, the coagulation sedimentation tank 1 includes a first tank body 12, a coagulant delivery pipe 13 arranged in the first tank body 12, and a coagulant metering pump 14 installed on one end of the coagulant delivery pipe 13; a partition block 121 is arranged in the first tank body 12, and the partition block 121 divides the internal space of the first tank body 12 into a mixing area 122 and a sedimentation area 123. The present invention is used to mix the coagulant with the water body through the setting of the coagulant delivery pipe 13, so that the impurities in the water body are coagulated and precipitated; the coagulant metering pump 14 is used to add a certain amount of coagulant to the water body, so as to prevent the cost increase, additional processing steps and equipment caused by the excessive addition of coagulant, and to avoid the coagulation and sedimentation effect caused by the insufficient addition of coagulant; the first tank body 12 is divided by the setting of the partition block 121, and the first tank body 12 is divided into a mixing area 122 where the water body and the coagulant are mixed, and a sedimentation area 123 where the impurities are mixed after the water body and the coagulant are mixed. It should be noted that the other end of the coagulant metering pump 14 is connected to a coagulant storage tank.

[0071] The coagulant delivery pipe 13 and one end of the water inlet pipe 5 are both located in the mixing area 122; the coagulant delivery pipe 13 is provided with delivery holes 131 at equal intervals, and the coagulant delivery pipe 13 is also provided with a one-way valve 132; the direction of the coagulant delivery pipe 13 is perpendicular to the direction of the water inlet pipe 5, and the minimum distance between the installation position of the coagulant delivery pipe 13 and the bottom surface of the first tank body 12 is equal to the minimum distance between the installation position of the water inlet pipe 5 and the bottom surface of the first tank body 12.

[0072] The coagulant delivery pipe 13 and the water inlet pipe 5 are both arranged in the mixing zone 122, so that after entering the first tank body 12, they are immediately in contact with the coagulant for coagulation, providing a basis for subsequent sedimentation; the delivery hole 131 is set to discharge the coagulant into the mixing zone 122 to mix with the water body; the one-way valve 132 is set to limit the movement direction of the coagulant to prevent the water body from flowing back into the coagulant metering pump 14, thereby protecting the coagulant metering pump 14; by limiting the installation height of the coagulant delivery pipe 13 and the installation height of the water inlet pipe 5, the water flowing out of the water inlet pipe 5 can impact on the coagulant delivery pipe 13 and quickly mix with the coagulant, thereby increasing the precipitation rate of impurities in the water body and improving the purification efficiency.

[0073] A water passage 124 is formed between the partition block 121 and the bottom surface of the inner cavity of the first tank body 12. A guide surface 125 is provided on the bottom surface of the partition block 121. An angle is formed between the guide surface 125 and the bottom surface of the first tank body 12, with the opening facing the water inlet pipe 5. The angle is an acute angle. The water mixed with the coagulant can be precipitated in the sedimentation area 123 by setting the water passage 124. The guide surface 125 can guide the flow direction of the water to flow to the bottom of the first tank body 12, and guide the coagulated impurities to move to the bottom of the first tank body 12, thereby improving the efficiency of coagulation and sedimentation.

[0074] A sedimentation frame 126 is provided in the sedimentation area 123, and a filter screen 127 is installed on the sedimentation frame 126; the distance between the first connecting pipe 11 and the bottom surface of the first tank body 12 is greater than the height of the sedimentation frame 126. The setting of the sedimentation frame 126 provides an installation position for the filter screen 127; the setting of the filter screen 127 is used to filter the water body to prevent the precipitated impurities and the water body from flowing into the activated carbon filter tank 2; by limiting the installation position of the first connecting pipe 11, it is ensured that only the water body passing through the filter screen 127 can enter through the first connecting pipe 11. It should be particularly noted that a slot is provided on the side of the sedimentation frame 126 where the filter screen 127 is not provided, which can be used to install a blocking plate to block the end of the sedimentation frame 126 facing the water passage 124 to prevent the sediment from shaking and entering the mixing area 122 when the sedimentation frame 126 is taken out for cleaning.

[0075] Specifically, the activated carbon filter 2 includes a second tank body 21, a plurality of mounting platforms 22 arranged in the second tank body 21, a support plate 23 mounted on the mounting platform 22, and an activated carbon layer 24 filled on the support plate 23; two sets of riding cards are staggered at the bottom of each support plate 23, and one set of riding cards is used to support the CO2 dosing device 7. The mounting platform 22 is used to provide an installation position for the support plate 23; the plurality of support plates 23 are used to support the activated carbon layer 24 of different particle sizes; the activated carbon layer 24 is used to adsorb the water body multiple times, thereby improving the purification effect of the water body. It should be particularly noted that the two sets of riding cards are used to support the CO2 dosing device 7 and the oxygen aeration pipe 232 respectively. The support plate 23 is provided with a through hole 231, and the aperture of the through hole 231 is smaller than the particle size of the activated carbon layer 24; the bottom of the support plate 23 is installed with an oxygen aeration pipe 232 through another set of riding cards.

[0076] The through hole 231 is provided to ensure that the water body can contact the activated carbon layer 24 through the support plate 23, so that the activated carbon in the activated carbon layer 24 can filter and purify the water body; the oxygen aeration pipe 232 is provided to dissolve oxygen into the water, increase the oxygen content in the water, and enable the microorganisms in the water to use oxygen to decompose the organic matter in the raw water, thereby further purifying the water body; the oxygen aeration pipe 232 and the carbon dioxide aeration pipe 75 are provided at the bottom of the support plate 23, so that the activated carbon can be effectively prevented from clogging the air outlet of the aeration pipe; the three mounting platforms 22 are provided in a stepped manner. It should be particularly noted that in the present application, there are three mounting platforms 22, that is, there are also three support plates 23, the activated carbon layer 24 is three layers, and the aperture size of the through holes 231 on the three support plates 23 gradually decreases from the bottom to the top of the second tank body 21, and the particle size of the activated carbon layer 24 also gradually decreases, thereby ensuring that the water body first contacts with large-particle activated carbon, then with medium-particle activated carbon, and finally with small-particle activated carbon; the aerobic aeration pipe 232 in the present application is a membrane assembly aeration pipe, which belongs to the prior art.

[0077] The aerated membrane filter tank 3 includes a third tank body 31, a plurality of membrane modules 32 mounted on the second connecting pipe group 20 and located in the third tank body 31; a CO2 dosing device 7 is mounted on the bottom surface of the inner cavity of the third tank body 31 and connected to the membrane module 32; and a water outlet pipe 6 is located at the bottom of the third tank body 31. The membrane module 32 is used to finely filter the water body, and the membrane module 32 belongs to the prior art, so this application will not be repeated here.

[0078] The CO2 dosing device 7 includes a carbon dioxide storage tank 71, an outlet pipe 72 installed on the carbon dioxide storage tank 71, a carbon dioxide metering pump 73 arranged on the carbon dioxide storage tank 71, a dosing main pipe 74 arranged on the outlet of the carbon dioxide metering pump 73, and two groups of carbon dioxide aeration pipes 75 arranged on the dosing main pipe 74, and the two groups of carbon dioxide aeration pipes 75 are respectively located in the aerated activated carbon filter 2 and the aerated membrane filter 3. The carbon dioxide storage tank 71 is used to store carbon dioxide; the carbon dioxide metering pump 73 is used to add carbon dioxide to the water body. It should be particularly noted that the carbon dioxide metering pump 73 is an adjustable metering pump; the carbon dioxide aeration pipe 75 is set, and the carbon dioxide aeration pipe 75 is set into two groups, one of which is fixed to the bottom of the support plate 23 by a riding card, and the other group of carbon dioxide aeration pipes 75 is connected to the membrane assembly 32, so as to further ensure that aluminum ions will not pass through the membrane assembly 32 and protect the membrane assembly 32.

[0079] The water quality online monitoring device 8 is provided with a first water quality monitoring probe 81 at the water inlet of the coagulation sedimentation tank 1, a second water quality monitoring probe 82 at the water outlet of the coagulation sedimentation tank, a third water quality monitoring probe 83 at the water outlet of the aerated activated carbon filter, and a fourth water quality monitoring probe 84 at the water outlet of the aerated membrane filter, which are respectively used to monitor the water quality conditions at each outlet. The water quality conditions here at least need to monitor pH value, turbidity and Al 3+ concentration.

[0080] For example, Figure 3 As shown, the present invention provides a specific control method for a high pH raw water purification system, and the specific steps are as follows:

[0081] The high pH raw water purification system is as described above, specifically:

[0082] S1: Set the following data information in the automation control system:

[0083] 1) The first deviation relationship curve between pH value and CO2 aeration amount;

[0084] 2) CO2 average deviation coefficient;

[0085] 3) The second deviation relationship curve between turbidity and the amount of coagulant added;

[0086] 4) Average coefficient of deviation of coagulant;

[0087] The method for obtaining the first deviation relationship curve is as follows: using high pH raw water as simulated water sample I, taking simulated water sample I, exposing CO2 gas thereto, measuring the changes in pH value and CO2 aeration amount, and establishing the first deviation relationship curve between pH value and CO2 aeration amount;

[0088] The method for obtaining the second deviation relationship curve is: take a simulated water sample I, add an aluminum salt coagulant thereto, measure the changes in turbidity and the amount of coagulant added, and establish a second deviation relationship curve between turbidity and the amount of coagulant added.

[0089] The control system of the present invention is suitable for raw water with high pH (i.e., high pH and high turbidity), which can effectively and accurately control the addition of CO2. More precisely, the water quality of high pH raw water is: pH 7.6-8.8; permanganate index 2.4-4.8 mg / L; ammonia nitrogen 0.1-0.6 mg / L; turbidity 12-25 NTU.

[0090] The method for obtaining the CO2 average deviation coefficient is as follows: According to formula (1), the CO2 average deviation coefficient is calculated;

[0091]

[0092] in, It represents the average deviation coefficient of CO2; i represents the value of the change of pH value in the simulated water sample I, i is from high to low, the initial value of i is the initial pH value of the simulated water sample I, generally 7.5-9.0, n is the lowest value after the pH value drops, generally 6.0-7.0; N represents the number of times the pH and its corresponding CO2 deviation aeration volume are measured during the process of pH dropping from i to n; Q di represents the CO2 deviation aeration volume when the pH value is i, which is obtained through the first deviation relationship curve; Q ti represents the theoretical aeration rate of CO2 when the pH value is i, which is obtained through the first theoretical relationship curve;

[0093] The method for obtaining the average deviation coefficient of the coagulant is as follows: According to formula (2), the average deviation coefficient of the coagulant is calculated;

[0094]

[0095] Among them, δ PAC represents the average deviation coefficient of the coagulant; j represents the value of the turbidity change in the simulated water sample II, j is from high to low, the initial value of j is the initial turbidity value of the simulated water sample II, generally 20-25, m is the lowest value after the turbidity decreases, generally 1-2; M represents the number of times the turbidity and its corresponding coagulant dosage are measured in the process of the turbidity decreasing from j to m; D dj represents the deviation dosage of coagulant when the turbidity is j, which is obtained through the second deviation relationship curve; D tj It represents the theoretical dosage of coagulant when the turbidity is j, which is obtained through the second theoretical relationship curve;

[0096] The first theoretical relationship curve is obtained by using the qualified effluent treated by the high pH raw water purification system as simulated water sample II, taking simulated water sample II, exposing it to CO2 gas, measuring the changes in pH value and CO2 aeration amount, and establishing the first theoretical relationship curve between pH value and CO2 aeration amount.

[0097] The second theoretical relationship curve is obtained by taking simulated water sample II, adding aluminum salt coagulant thereto, measuring the changes in turbidity and the amount of coagulant added, and establishing the second theoretical relationship curve between turbidity and the amount of coagulant added.

[0098] The qualified effluent treated by the high pH raw water purification system refers to the water that meets the standard requirements, and its water quality is: pH 6.5-7.5; permanganate index 1.0-2.5 mg / L; ammonia nitrogen 0.04-0.1 mg / L; turbidity 0-0.2 NTU.

[0099] It should be noted that the data of 1) to 4) above can be directly input into the data processing and analysis module in the feedback control system, so that the module can retrieve the data and perform data processing and analysis, calculate and correct the CO2 aeration amount and the amount of coagulant added. The optimized solution can also add a sampling monitoring module to the feedback control system, directly obtain high pH raw water from the influent, obtain qualified effluent from the effluent, and monitor it, and then transmit the obtained data of 1) to 4) to the data processing and analysis module for data processing.

[0100] S2: Real-time monitoring of the pH value at the inlet of the coagulation sedimentation tank, the pH value at the inlet of the aerated activated carbon filter, the pH value at the inlet of the aerated membrane filter, and the turbidity at the outlet of the coagulation sedimentation tank;

[0101] During the actual control process, water quality monitoring probes are installed at each water inlet and outlet to ensure the normal water quality of each pipeline and facilitate maintenance.

[0102] S3: Retrieve the real-time pH value data of S2, calculate the real-time deviation aeration volume of CO2 in each pool according to the first deviation relationship curve, and then calculate the real-time corrected aeration volume of CO2 according to the internal average deviation coefficient of CO2; the calculation formula of the real-time corrected aeration volume of CO2 is: real-time corrected aeration volume of CO2 = real-time deviation aeration volume of CO2 × CO2 deviation coefficient;

[0103] S4: Retrieve the real-time turbidity data of S2, calculate the real-time deviation addition amount of the coagulant according to the second deviation relationship curve, and then calculate the real-time correction addition amount of the coagulant in the coagulation sedimentation tank according to the internal coagulant average deviation coefficient;

[0104] The calculation formula for the real-time correction addition amount of coagulant is: real-time correction addition amount of coagulant = real-time deviation addition amount of coagulant × average deviation coefficient of coagulant.

[0105] There is no sequential relationship between steps S3 and S4, and they can be performed simultaneously or in steps. The calculation process is all executed in the data processing and analysis module.

[0106] S5: According to the real-time correction of the aeration volume of CO2 and the real-time correction of the addition volume of coagulant, the dosage of CO2 in the aeration activated carbon filter and the aeration membrane filter, as well as the dosage of CO2 and the dosage of coagulant in the coagulation sedimentation tank are controlled.

[0107] The execution of step S5 is controlled by the feedback control module to realize the dosage of CO2 and the dosage of coagulant. For the aerated activated carbon filter and the aerated membrane filter, oxygen needs to be aerated, and the aeration method adopts the conventional method, which is not described in detail in the present invention.

[0108] S6: Real-time monitoring of Al at the outlet of the aerated activated carbon filter 3+ Concentration, if Al 3+ When the concentration is 0.05-0.2 mg / L, the effluent from the aerated activated carbon filter will be returned to the coagulation sedimentation tank.

[0109] It should be noted that high pH raw water often contains high turbidity, and turbidity will affect the accuracy of the relationship between pH value and CO2 aeration volume. By setting the relationship curve and average deviation coefficient, the CO2 aeration volume and the amount of coagulant added can be effectively corrected in real time, thereby achieving refined CO2 and coagulant addition control. Similarly, the concentration of aluminum ions will also affect the amount of coagulant added and will also affect the membrane, so S6 is used to reduce Al 3+ The influence of concentration.

[0110] For example, the present application also provides an application case. For a water plant in a certain city, the high pH raw water purification system of the present application is used for water purification. The raw water of the water plant comes from urban wetland water, and the water quality is: pH 7.8-8.4; permanganate index is 2.8-3.8 mg / L; ammonia nitrogen is 0.1-0.3 mg / L; turbidity is 13.5-17.8 NTU. Through the water purification system of the present application and its supporting control system, the CO2 aeration volume can be reduced from the original 13 mg / L to 9 mg / L, the amount of coagulant is reduced by 25%-35%, and the final water purification efficiency can be increased by 15%-20%; the effluent water quality is pH 6.8-7.5; the permanganate index is 1.4-1.9 mg / L; the ammonia nitrogen is 0.04-0.07 mg / L; the turbidity is 0-0.12 NTU.

[0111] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for a high pH raw water purification system, characterized in that: The high pH raw water purification system comprises a coagulation sedimentation tank, an aerated activated carbon filter tank and an aerated membrane filter tank, and an automatic control system; Control methods include: S1: Set the following data information in the automation control system: 1) The first deviation relationship curve between pH value and CO2 aeration amount; 2) CO2 average deviation coefficient; 3) The second deviation relationship curve between turbidity and the amount of coagulant added; 4) Average coefficient of deviation of coagulant; S2: Real-time monitoring of the pH value at the inlet of the coagulation sedimentation tank, the pH value at the inlet of the aerated activated carbon filter, the pH value at the inlet of the aerated membrane filter, and the turbidity at the outlet of the coagulation sedimentation tank; S3: Retrieve the real-time pH value data of S2, calculate the real-time deviation aeration volume of CO2 in each pool according to the first deviation relationship curve, and then calculate the real-time corrected aeration volume of CO2 according to the internal CO2 average deviation coefficient; S4: Retrieve the real-time turbidity data of S2, calculate the real-time deviation addition amount of the coagulant according to the second deviation relationship curve, and then calculate the real-time correction addition amount of the coagulant in the coagulation sedimentation tank according to the internal coagulant average deviation coefficient; S5: According to the real-time correction of the aeration volume of CO2 and the real-time correction of the addition volume of coagulant, the dosage of CO2 in the aeration activated carbon filter and the aeration membrane filter, as well as the dosage of CO2 and the dosage of coagulant in the coagulation sedimentation tank are controlled.

2. The control method of the high pH raw water purification system according to claim 1, characterized in that: In S1, the method for obtaining the first deviation relationship curve is: using high pH raw water as simulated water sample I, taking simulated water sample I, exposing CO2 gas thereto, measuring the changes in pH value and CO2 aeration amount, and establishing a first deviation relationship curve between pH value and CO2 aeration amount; The method for obtaining the second deviation relationship curve is: take a simulated water sample I, add an aluminum salt coagulant thereto, measure the changes in turbidity and the amount of coagulant added, and establish a second deviation relationship curve between turbidity and the amount of coagulant added.

3. The control method of the high pH raw water purification system according to claim 2, characterized in that: In S1, the method for obtaining the CO2 average deviation coefficient is: According to formula (1), the average deviation coefficient of CO2 is calculated; in, It represents the average deviation coefficient of CO2; i represents the value of the change of pH value in the simulated water sample I, i is from high to low, the initial value of i is the initial pH value of the simulated water sample I, generally 7.5-9.0, n is the lowest value after the pH value drops, generally 6.0-7.0; N represents the number of times the pH and its corresponding CO2 deviation aeration volume are measured during the process of pH dropping from i to n; Q di represents the CO2 deviation aeration volume when the pH value is i, which is obtained through the first deviation relationship curve; Q ti represents the theoretical aeration rate of CO2 when the pH value is i, which is obtained through the first theoretical relationship curve; The first theoretical relationship curve is obtained by using the qualified effluent treated by the high pH raw water purification system as simulated water sample II, taking simulated water sample II, exposing it to CO2 gas, measuring the changes in pH value and CO2 aeration amount, and establishing the first theoretical relationship curve between pH value and CO2 aeration amount.

4. The control method of the high pH raw water purification system according to claim 3, characterized in that: In S1, the method for obtaining the average deviation coefficient of the coagulant is: According to formula (2), the average deviation coefficient of coagulant is calculated; Among them, δ PAC It represents the average deviation coefficient of the coagulant; j represents the value of the turbidity change in the simulated water sample I, j is from high to low, the initial value of j is the initial turbidity value of the simulated water sample I, generally 20.0-25.0, m is the lowest value after the turbidity decreases, generally 0-1.0; M represents the number of times the turbidity and its corresponding coagulant dosage are measured in the process of the turbidity decreasing from j to m; D dj represents the deviation dosage of coagulant when the turbidity is j, which is obtained through the second deviation relationship curve; D tj It represents the theoretical dosage of coagulant when the turbidity is j, which is obtained through the second theoretical relationship curve; The second theoretical relationship curve is obtained by taking a simulated water sample II, adding an aluminum salt coagulant thereto, measuring the changes in turbidity and the amount of coagulant added, and establishing a second theoretical relationship curve between turbidity and the amount of coagulant added.

5. The control method of the high pH raw water purification system according to claim 4, characterized in that: The water quality of the simulated water sample I is: pH 7.6-8.8; permanganate index 2.4-4.8 mg / L; ammonia nitrogen 0.1-0.6 mg / L; turbidity 12-25 NTU; the water quality of the simulated water sample II is: pH 6.5-7.5; permanganate index 1.0-2.5 mg / L; ammonia nitrogen 0.04-0.1 mg / L; turbidity 0-0.2 NTU.

6. The control method of the high pH raw water purification control system according to claim 1, characterized in that: In S3, the calculation formula of CO2 real-time corrected aeration volume is: CO2 real-time corrected aeration volume = CO2 real-time deviation aeration volume × CO2 deviation coefficient; In S4, the calculation formula of the real-time correction addition amount of coagulant is: real-time correction addition amount of coagulant = real-time deviation addition amount of coagulant × average deviation coefficient of coagulant.

7. The control method of the high pH raw water purification control system according to claim 1, characterized in that: The control method further includes: S6: real-time monitoring of the Al at the outlet of the aerated activated carbon filter tank. 3+ Concentration, if Al 3+ When the concentration is 0.05-0.2 mg / L, the effluent from the aerated activated carbon filter will be returned to the coagulation sedimentation tank.

8. A high pH raw water purification system, characterized in that: It comprises a coagulation sedimentation tank, an aerated activated carbon filter tank, an aerated membrane filter tank and an automatic control system; the automatic control system executes the steps of the control method as described in any one of claims 1 to 7.

9. The high pH raw water purification system according to claim 8, characterized in that: The automatic control system includes: water quality online monitoring equipment, CO2 dosing equipment, coagulant dosing equipment and feedback control system; The water quality online monitoring equipment is equipped with water quality monitoring probes installed at the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank, the outlet of the aerated activated carbon filter tank and the outlet of the aerated membrane filter tank; The CO2 dosing equipment is provided with CO2 aeration ports respectively connected with the coagulation sedimentation tank, the aerated activated carbon filter tank and the aerated membrane filter tank; The coagulant dosing device is provided with a coagulant dosing port connected to the coagulation sedimentation tank; A feedback control system executes the steps of the control method according to any one of claims 1 to 7.

10. The high pH raw water purification system according to claim 9, characterized in that: The feedback control system comprises: an information acquisition module, a data processing and analysis module and a feedback control module; An information collection module is used to receive water quality data information from a water quality monitoring probe and feed the water quality data information back to a data processing and analysis module; The data processing and analysis module receives the data information from the information acquisition module, calculates and corrects the CO2 aeration amount and the coagulant addition amount; Feedback control module, including CO2 addition control submodule and coagulant addition control submodule; The CO2 dosing control submodule receives data information from the data processing and analysis module to control the opening and closing of the CO2 aeration port and the gas flow rate; The coagulant addition control submodule controls the opening and closing of the coagulant addition port and the coagulant addition flow rate.

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