A control method and control system of a high-pH raw water purification system

Abstract

The application provides a control method and a control system of a high-pH raw water purification system, which acquires and presets 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; monitors the pH value of each water inlet and the turbidity and Al 3+ concentration of the coagulation sedimentation pool outlet in real time; obtains a CO2 real-time correction aeration amount and a coagulant real-time correction adding amount; and finally, controls the aeration amount of CO2 in an aeration activated carbon filter and an aeration membrane filter and the aeration amount of CO2 and the adding amount of coagulant in the coagulation sedimentation pool according to the CO2 real-time correction aeration amount and the coagulant real-time correction adding amount. The application effectively improves the coagulation sedimentation effect and reduces the concentration of aluminum ions in the water body through fine CO2 automatic adding control, thereby prolonging the membrane service life and promoting the effective operation of the whole water purification process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water purification process, and particularly relates to a control method and a control system of a high-pH raw water purification system. BACKGROUND

[0002] In view of the problem that high pH of raw water leads to excessive aluminum concentration of finished water, the main response of the water plant is to add acidification coagulant, increase the dosage of coagulant or directly add acid to the raw water to reduce the pH. However, the above methods have disadvantages: the use of acidification coagulant and the increase of coagulant dosage will increase the production cost, the residual aluminum in the effluent is difficult to control, there is still a risk of exceeding the standard, and the frequent switching of coagulant is not conducive to the stable operation of the water plant process; the raw water acidification method needs to build an acidification system, which has large engineering investment, and strong acid is corrosive, which has safety hazards.

[0003] In the water purification process, the downstream of the coagulation device usually involves various membrane treatment processes, and the high concentration of aluminum ions in the water caused by high pH of raw water will penetrate the membrane components in the subsequent process, causing membrane damage and membrane pollution; therefore, in order to avoid the penetration of aluminum ions in the subsequent water purification process to cause membrane damage and membrane pollution, it is necessary to adjust the pH of the raw water; adding CO2 to adjust the pH 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 sedimentation effect and the concentration of aluminum ions. The patent application with the application publication number CN104649473A discloses a device and method for controlling residual aluminum concentration in high-pH raw water treatment process. The method adjusts the pH of the water body by adding carbon dioxide to the high-pH raw water, thereby avoiding the corrosion of liquid strong acids such as sulfuric acid and hydrochloric acid to the production equipment of the water plant, and the pollution to the raw water; through the mixing effect with aluminum sulfate coagulant, the aluminum is precipitated and filtered as hydroxide, which is more pure and environmentally friendly.

[0005] However, the above method is aimed at ordinary reservoir raw water, and the water quality of reservoir raw water is better, and the accurate regulation of CO2 is easier to achieve; in the actual urban water supply system, in order to ensure sufficient urban water supply sources, the reservoir raw water is only a part of the water supply source, and water sources such as wetlands and lakes also need to be supplemented. For wetland and lake water sources, the turbidity of raw water and the metabolic products produced by microorganisms and plants are relatively high, and these substances will interfere with the accurate regulation of CO2, and the accurate regulation of CO2 cannot be achieved.

[0006] Therefore, it is necessary to provide a high-pH raw water purification control system and control method, which promotes the coagulation and sedimentation effect and reduces the concentration of aluminum ions by realizing more accurate CO2 addition control, avoids the damage of various membrane materials in the subsequent process, and thus promotes the effective operation of the entire water purification process. SUMMARY

[0007] The application provides a control method and control system for a high-pH raw water purification system, which finely controls the addition of CO2, 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 application provides a control method for a high-pH raw water purification system, which comprises a coagulation and sedimentation tank, an aerated activated carbon filter tank, and an aerated membrane filter tank, and an automatic control system.

[0010] The control method comprises the following steps:

[0011] S1: setting the following data information in the automatic control system:

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

[0013] 2) a CO2 average deviation coefficient;

[0014] 3) a second deviation relationship curve between the turbidity and the coagulant addition amount;

[0015] 4) a coagulant average deviation coefficient;

[0016] S2: real-time monitoring of the pH value of the coagulation and sedimentation tank inlet, the pH value of the aerated activated carbon filter tank inlet, the pH value of the aerated membrane filter tank inlet, and the turbidity of the coagulation and sedimentation tank outlet; the pH value of the inlet is 7.6-8.8;

[0017] S3: calling the real-time pH value data of S2, calculating the CO2 real-time deviation aeration amount in each tank according to the first deviation relationship curve, and calculating the CO2 real-time correction aeration amount according to the internally set CO2 average deviation coefficient;

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

[0019] S5: According to the real-time correction of the amount of CO2 and the real-time correction of the amount of coagulant, the amount of CO2 in the aeration activated carbon filter and the aeration membrane filter is controlled, and the amount of CO2 and the amount of coagulant in the coagulation sedimentation tank is controlled.

[0020] The present application firstly sets CO2 aeration ports in the coagulation sedimentation tank, the aeration activated carbon filter and the aeration membrane filter to realize the precise control of CO2 aeration in steps; and the deviation coefficient is set to correct the amount of CO2 in each tank and the amount of coagulant in the coagulation sedimentation tank; thereby ensuring efficient water purification of raw water while reducing CO2 aeration and coagulant addition.

[0021] Further, in S1, the first deviation relationship curve is obtained by taking high-pH raw water as simulation water sample I, exposing CO2 gas to the simulation water sample I, measuring the changes of pH value and CO2 aeration amount, and establishing the first deviation relationship curve between the pH value and the CO2 aeration amount.

[0022] The second deviation relationship curve is obtained by taking simulation water sample I, adding aluminum salt coagulant to it, measuring the changes of turbidity and coagulant addition amount, and establishing the second deviation relationship curve between turbidity and coagulant addition amount.

[0023] Further, in S1, the CO2 average deviation coefficient is obtained by:

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

[0025] (1);

[0026] Wherein, The CO2 average deviation coefficient is represented; i represents the value of the change of the pH value in the simulation water sample I, i is from high to low, the initial value of i is the initial pH value of the simulation water sample I, generally 7-8, n is the lowest value after the pH value decreases, generally 5-6; N represents the number of times of measuring the pH value and the corresponding CO2 deviation aeration amount in the process of the pH value decreasing from i to n; The CO2 deviation aeration amount when the pH value is i is obtained by the first deviation relationship curve; The CO2 theoretical aeration amount when the pH value is i is obtained by the first theoretical relationship curve;

[0027] The first theoretical relationship curve is obtained by taking the standard effluent of the high-pH raw water purification system as simulation water sample II, exposing CO2 gas to the simulation water sample II, measuring the changes of pH value and CO2 aeration amount, and establishing the first theoretical relationship curve between the pH value and the CO2 aeration amount.

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

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

[0030] (2);

[0031] wherein, represents the average deviation coefficient of the coagulant; j represents the value of the change in turbidity of 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 minimum value after the turbidity decreases, generally 1-2; M represents the number of times of measuring the turbidity and the corresponding coagulant dosage in the process of the turbidity decreasing from j to m; represents the deviation dosage of the coagulant when the turbidity is j, which is obtained through the second deviation relationship curve; represents the theoretical dosage of the 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 the simulated water sample II, adding an aluminum salt coagulant thereto, measuring the change in turbidity and coagulant dosage, and establishing the second theoretical relationship curve between the turbidity and the coagulant dosage.

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

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

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

[0036] Further, the control method further comprises: S6: real-time monitoring of the Al 3+ concentration at the outlet of the aeration activated carbon filter, if the Al 3+ concentration is 0.05-0.20 mg / L, the effluent of the aeration activated carbon filter is reflowed to the coagulation sedimentation tank.

[0037] The application further 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 performs the steps of the control method as described above.

[0038] Further, the automatic control system comprises water quality online monitoring equipment, CO2 dosing equipment, coagulant dosing equipment and a feedback control system.

[0039] The water quality online monitoring equipment is provided with water quality monitoring probes respectively 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 communicated with the coagulation sedimentation tank, the aerated activated carbon filter tank and the aerated membrane filter tank.

[0041] The coagulant dosing equipment is provided with a coagulant dosing port communicated with the coagulation sedimentation tank.

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

[0043] Further, the feedback control system comprises an information acquisition module, a data processing and analysis module and a feedback control module.

[0044] The information acquisition module is used for receiving water quality data information of the water quality monitoring probes and feeding back the water quality data information to the data processing and analysis module.

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

[0046] The feedback control module comprises a CO2 dosing control submodule and a coagulant dosing control submodule.

[0047] The CO2 dosing control submodule receives data information of the data processing and analysis module, controls opening and closing of the CO2 aeration ports and gas flow.

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

[0049] Further, the feedback control system further comprises a sampling and monitoring module used for sampling water inlet and water outlet of the purification system, detecting and acquiring data information of a first deviation relationship curve, a CO2 average deviation coefficient, a second deviation relationship curve and a coagulant average deviation coefficient and transmitting the data information to the data processing and analysis module.

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

[0051] (1) The present application effectively improves the coagulation and sedimentation effect by fine CO2 automated dosing control, and reduces the concentration of aluminum ions in the water body, thereby prolonging the membrane life and promoting the effective operation of the entire water purification process.

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

[0053] (3) Reduce coagulant dosage: Under the optimized pH condition, the use amount of aluminum salt coagulant is reduced, the operation cost is reduced, and the potential environmental impact of aluminum salt coagulant is reduced.

[0054] (4) Reduce the use of chemical additives: Using CO2 instead of traditional acidification coagulant or directly adding acid, reducing the use of chemical additives, reducing environmental pollution and operation risk.

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

[0056] (6) The present application has good operation simplicity, system stability and scalability, and is suitable for water plants of different scales, and is easy to integrate with other water treatment processes. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 It is an embodiment of the mechanism schematic diagram of the high-pH raw water purification control system of the present application.

[0058] Among them, 1. Coagulation and sedimentation tank; 2. Aeration activated carbon filter; 3. Aeration membrane filter; 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 It is a structure block diagram of an embodiment of the feedback control system of the present application.

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

[0061] Figure 3 It is a whole structure schematic diagram of the device part of the high-pH raw water purification control system of the present application.

[0062] Figure 4 It is a whole structure top view of the device part of the high-pH raw water purification control system of the present application.

[0063] Identified in the figure: 1, coagulation sedimentation tank; 11, first connecting pipe; 12, first tank body; 121, partition block; 122, mixing area; 123, sedimentation area; 124, water passage; 125, guide surface; 126, sedimentation frame; 127, filter screen; 13, coagulant feeding pipe; 131, feeding hole; 132, one-way valve; 14, coagulant metering pump; 15, coagulant storage tank; 2, aerated activated carbon filter tank; 20, second connecting pipe group; 21, second tank body; 22, mounting table; 23, support plate; 231, through hole; 232, oxygen aeration pipe; 234, oxygen storage tank; 24, activated carbon layer; 3, aerated membrane filter tank; 31, third tank body; 32, membrane assembly; 7, CO2 feeding equipment; 71, carbon dioxide storage tank; 72, gas outlet pipe; 73, carbon dioxide metering pump; 74, feeding 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 The flowchart of an embodiment of the high-pH raw water purification system control method. DETAILED DESCRIPTION

[0065] To make the objectives, technical solutions and advantages of the present application clearer, the specific embodiments of the high-pH raw water purification control system and control method are described below with reference to the drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

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

[0067] The present application provides a case of a high-pH raw water purification system, as shown in Figure 1 The high-pH raw water purification system of the present application mainly comprises 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 equipment 41, a CO2 feeding equipment 42, a coagulant feeding equipment 43, and a feedback control system 44. The automatic control can use a PLC control system or a DCS control system.

[0068] As shown in Figure 2As shown, the feedback control system 44 provided by the present application specifically comprises: an information acquisition module 441, a data processing and analysis module 442 and a feedback control module 443; the information acquisition module is used for receiving water quality data information of a water quality monitoring probe, and feeding back the water quality data information to the data processing and analysis module; the data processing and analysis module receives data information of the information acquisition module, calculates and corrects CO2 aeration quantity and coagulant addition quantity; the feedback control module comprises a CO2 addition control submodule and a coagulant addition control submodule; the CO2 addition control submodule receives data information of the data processing and analysis module, controls opening and closing of a CO2 aeration port and gas flow; the coagulant addition control submodule controls opening and closing of a coagulant addition port and coagulant addition flow.

[0069] The present application also provides a specific structure of the high-pH raw water purification system device part, as shown in the figure. Figures 3-4 As shown, the high-pH raw water purification system device structure part comprises a coagulation sedimentation tank 1, a water 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 aeration activated carbon filter tank 2 in communication with the coagulation sedimentation tank 1 through the first connecting pipe 11, a second connecting pipe group 20 arranged on the aeration activated carbon filter tank 2, an aeration membrane filter tank 3 in communication with the aeration activated carbon filter tank 2 through the second connecting pipe group 20, a CO2 addition device 7 in communication with the aeration activated carbon filter tank 2 and the aeration membrane filter tank 3, and a water outlet pipe 6 arranged on the aeration membrane filter tank 3.

[0070] Specifically, the coagulation sedimentation tank 1 comprises a first tank body 12, a coagulant feeding pipe 13 arranged on the first tank body 12, and a coagulant metering pump 14 mounted on one end of the coagulant feeding 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. Through the arrangement of the coagulant feeding pipe 13, the coagulant is mixed with the water body, so that the impurities in the water body are coagulated and precipitated; through the arrangement of the coagulant metering pump 14, a certain amount of coagulant is added to the water body, which prevents the increase of cost, additional processing steps and equipment caused by excessive addition of coagulant, and avoids the influence of coagulation and precipitation effect caused by insufficient addition of coagulant; through the arrangement of the partition block 121, the first tank body 12 is divided into the mixing area 122 for mixing the water body with the coagulant and the sedimentation area 123 for the impurities after the water body is mixed with the coagulant. It should be particularly noted that the other end of the coagulant metering pump 14 is connected with a coagulant storage tank.

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

[0072] The coagulant feeding pipe 13 and the water inlet pipe 5 are both arranged in the mixing area 122, so that the water in the first pool body 12 immediately contacts the coagulant for coagulation after entering the first pool body 12, thereby providing a basis for subsequent sedimentation; the feeding holes 131 are arranged for discharging the coagulant into the mixing area 122 to mix with the water; the one-way valve 132 is arranged to limit the movement direction of the coagulant, thereby preventing the water from flowing backward into the coagulant metering pump 14 and protecting the coagulant metering pump 14; the installation height of the coagulant feeding pipe 13 and the installation height of the water inlet pipe 5 are limited, so that the water flowing out of the water inlet pipe 5 can impact on the coagulant feeding pipe 13 to quickly mix with the coagulant, thereby improving the sedimentation speed of impurities in the water and improving the purification efficiency.

[0073] The water passage 124 is formed between the separation block 121 and the bottom surface of the inner cavity of the first pool body 12, the bottom surface of the separation block 121 is provided with a guide surface 125, and the guide surface 125 and the bottom surface of the first pool body 12 form an included angle with an opening facing the water inlet pipe 5, and the included angle is an acute angle. The water passage 124 is arranged to enable the water mixed with the coagulant to perform impurity sedimentation in the sedimentation area 123; the guide surface 125 is arranged to guide the flow direction of the water, so that the water flows to the bottom of the first pool body 12, and the coagulated impurities are guided to move to the bottom of the first pool body 12, thereby improving the coagulation and sedimentation efficiency.

[0074] The sedimentation frame 126 is arranged in the sedimentation area 123, and the 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 pool body 12 is greater than the height of the sedimentation frame 126. The sedimentation frame 126 is arranged to provide an installation position for the filter screen 127; the filter screen 127 is arranged to filter the water, thereby preventing the sedimented impurities and the water from flowing into the activated carbon filter tank 2; the installation position of the first connecting pipe 11 is limited to ensure that only the water passing through the filter screen 127 can enter through the first connecting pipe 11. It should be particularly noted that the side of the sedimentation frame 126 without the filter screen 127 is provided with a slot, which can be used to install a blocking plate to block the end of the sedimentation frame 126 facing the water passage 124, thereby preventing the sediment from entering the mixing area 122 when the sedimentation frame 126 is removed for cleaning.

[0075] Specifically, the activated carbon filter 2 comprises a second pool body 21, a plurality of mounting tables 22 arranged in the second pool body 21, support plates 23 mounted on the mounting tables 22, and activated carbon layers 24 filled on the support plates 23. Two groups of stirrups are staggered at the bottom of each support plate 23, and one group of stirrups is used to support the CO2 adding device 7. The mounting tables 22 are arranged to provide mounting positions for the support plates 23. The plurality of support plates 23 are arranged to support activated carbon layers 24 of different particle sizes. The activated carbon layers 24 are arranged to adsorb the water body multiple times, thereby improving the purification effect of the water body. It should be particularly pointed out that the two groups of stirrups are used to support the CO2 adding 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 provided with the oxygen aeration pipe 232 through the other group of stirrups.

[0076] The through hole 231 is arranged 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 arranged to dissolve oxygen into the water, increase the oxygen content in the water, and make the microorganisms in the water decompose the organic matter in the raw water by using oxygen, thereby further purifying the water body. The oxygen aeration pipe 232 and the carbon dioxide aeration pipe 75 are arranged at the bottom of the support plate 23, which can effectively prevent the activated carbon from blocking the gas outlet of the aeration pipe. The three mounting tables 22 are arranged in steps. It should be particularly pointed out that the number of mounting tables 22 in the present application is three, that is, the number of support plates 23 is also three, and the activated carbon layer 24 is three layers. The aperture of the through hole 231 on the three support plates 23 gradually decreases from the bottom to the top of the second pool body 21, and the particle size of the activated carbon layer 24 also gradually decreases, thereby ensuring that the water body first contacts the large-particle activated carbon, then contacts the medium-particle activated carbon, and finally contacts the small-particle activated carbon. The aerobic aeration pipe 232 in the present application is a membrane module aeration pipe, which belongs to the prior art.

[0077] The aeration membrane filter 3 comprises a third pool body 31, a plurality of membrane modules 32 mounted on the second connecting pipe group 20 and located in the third pool body 31, and the CO2 adding device 7 is mounted on the inner cavity bottom surface of the third pool body 31 and connected with the membrane module 32. The water outlet pipe 6 is located at the bottom of the third pool body 31. The membrane module 32 is arranged to fine filter the water body, and the membrane module 32 belongs to the prior art, so the present application will not be described here.

[0078] The CO2 adding device 7 comprises a carbon dioxide storage tank 71, a gas 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 total adding pipe 74 arranged on the carbon dioxide metering pump 73, two groups of carbon dioxide aeration pipes 75 arranged on the total adding pipe 74, and the two groups of carbon dioxide aeration pipes 75 are arranged in the aeration activated carbon filter 2 and the aeration membrane filter 3 respectively. The carbon dioxide storage tank 71 is arranged for storing carbon dioxide; the carbon dioxide metering pump 73 is arranged for adding carbon dioxide into the water body, and it is particularly pointed out that the carbon dioxide metering pump 73 is an adjustable metering pump; the carbon dioxide aeration pipes 75 are arranged in two groups, one group is fixed on the bottom of the support plate 23 through a horse clamp, and the other group of carbon dioxide aeration pipes 75 is connected with the membrane assembly 32, which further ensures that the aluminum ions cannot pass through the membrane assembly 32 and protects the membrane assembly 32.

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

[0080] For example, as shown in Figure 3 the present application provides a specific control method of the 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, and specifically comprises:

[0082] S1: setting the following data information in the automatic control system:

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

[0084] 2) a CO2 average deviation coefficient;

[0085] 3) a second deviation relationship curve between the turbidity and the coagulant adding amount;

[0086] 4) a coagulant average deviation coefficient;

[0087] The first deviation relationship curve is obtained by taking the high-pH raw water as a simulation water sample I, adding CO2 gas into the simulation water sample I, measuring the changes of the pH value and the CO2 aeration amount, and establishing the first deviation relationship curve between the pH value and the CO2 aeration amount;

[0088] The second deviation relationship curve is obtained by adding an aluminum salt coagulant to the simulated water sample I, measuring the turbidity and the coagulant addition amount, and establishing a second deviation relationship curve between the turbidity and the coagulant addition amount.

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

[0090] The CO2 average deviation coefficient is obtained according to formula (1).

[0091] (1);

[0092] wherein, represents the CO2 average deviation coefficient; i represents the value of the change in the pH of 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, which is generally 7.5-9.0, n is the lowest value after the pH value decreases, which is generally 6.0-7.0; N represents the measurement times of the pH and the corresponding CO2 deviation aeration amount in the process of the decrease of the pH from i to n; represents the CO2 deviation aeration amount when the pH is i, which is obtained through the first deviation relationship curve; represents the CO2 theoretical aeration amount when the pH is i, which is obtained through the first theoretical relationship curve;

[0093] The coagulant average deviation coefficient is obtained according to formula (2).

[0094] (2);

[0095] wherein, represents the coagulant average deviation coefficient; j represents the value of the change in the turbidity of 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, which is generally 20-25, m is the lowest value after the turbidity decreases, which is generally 1-2; M represents the measurement times of the turbidity and the corresponding coagulant addition amount in the process of the decrease of the turbidity from j to m; represents the coagulant deviation addition amount when the turbidity is j, which is obtained through the second deviation relationship curve; represents the coagulant theoretical addition amount when the turbidity is j, which is obtained through the second theoretical relationship curve;

[0096] The first theoretical relationship curve is obtained by taking the treated water of the high-pH raw water purification system as a simulated water sample II, exposing CO2 gas into the simulated water sample II, measuring the changes of the pH value and the CO2 exposure amount, and establishing the first theoretical relationship curve between the pH value and the CO2 exposure amount.

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

[0098] The treated water of the high-pH raw water purification system refers to water meeting the standard requirements, and the water quality is as follows: the pH value is 6.5-7.5; the permanganate index is 1.0-2.5 mg / L; the ammonia nitrogen is 0.04-0.1 mg / L; and the turbidity is 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 for data processing and analysis, and calculate and correct the CO2 exposure amount and the coagulant addition amount. In the optimized scheme, a sampling and monitoring module can also be added to the feedback control system to directly obtain the high-pH raw water from the influent and the treated water from the effluent, and to monitor and obtain the data of 1) to 4) for data processing.

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

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

[0102] S3: Retrieving the real-time pH value data of S2, calculating the CO2 real-time deviation exposure amount in each tank according to the first deviation relationship curve, and calculating the CO2 real-time correction exposure amount according to the internally set CO2 average deviation coefficient; the calculation formula of the CO2 real-time correction exposure amount is: CO2 real-time correction exposure amount = CO2 real-time deviation exposure amount × CO2 average deviation coefficient;

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

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

[0105] Steps S3 and S4 have no sequence relationship, can be performed simultaneously or in steps, and the calculation process is performed in the data processing and analysis module.

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

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

[0108] S6: Real-time monitoring of the Al 3+ concentration of the effluent outlet of the aeration activated carbon filter, if the Al 3+ concentration is 0.05-0.2 mg / L, the effluent of the aeration activated carbon filter is reflowed to the coagulation and sedimentation tank.

[0109] It should be noted that the high-pH raw water often contains high turbidity, and the turbidity will affect the accuracy between the pH value and the CO2 aeration amount. Through the setting of the relationship curve and the average deviation coefficient, the aeration amount of CO2 and the addition amount of coagulant can be effectively corrected in real time, so as to realize the fine CO2 and coagulant dosing control. Similarly, the concentration of aluminum ions also affects the addition amount of coagulant and also affects the membrane, so S6 is adopted to reduce the influence of the Al 3+ concentration.

[0110] For example, the application also provides an application case. For a certain water plant in a certain city, the high-pH raw water purification system is used for water purification treatment, the raw water of the water plant comes from the urban wetland water, and the water quality is: pH is 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 and the matching control system, the CO2 aeration amount can be reduced from 13 mg / L to 9 mg / L, the coagulant consumption is reduced by 25%-35%, and the final water purification efficiency can be improved by 15%-20%; the effluent water quality is: pH is 6.8-7.5; permanganate index is 1.4-1.9 mg / L; ammonia nitrogen is 0.04-0.07 mg / L; turbidity is 0-0.12 NTU.

[0111] The above detailed description of the specific embodiments of the present application has described the technical solutions and beneficial effects of the present application, and it should be understood that the above description is only the most preferred embodiment of the present application and is not intended to limit the present application. Any modifications, supplements and equivalent replacements made within the principle range of the present application shall be included in the protection range of the present application.

Claims

1. A control method of a high-pH raw water purification system, characterized by, 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. The control method comprises: S1: setting the following data information in the automatic control system: 1) a first deviation relationship curve between the pH value and the CO2 aeration amount; 2) a CO2 average deviation coefficient; 3) a second deviation relationship curve between the turbidity and the coagulant addition amount; 4) a coagulant average deviation coefficient; 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 tank, the pH value at the inlet of the aerated membrane filter tank, and the turbidity at the outlet of the coagulation sedimentation tank; the pH value at the inlet is 7.6-8.8; S3: retrieving the real-time pH value data of S2, calculating the CO2 real-time deviation aeration amount in each tank according to the first deviation relationship curve, and calculating the CO2 real-time correction aeration amount according to the internally set CO2 average deviation coefficient; S4: retrieving the real-time turbidity data of S2, calculating the coagulant real-time deviation addition amount according to the second deviation relationship curve, and calculating the coagulant real-time correction addition amount in the coagulation sedimentation tank according to the internally set coagulant average deviation coefficient; S5: controlling the addition amount of CO2 in the aerated activated carbon filter tank and the aerated membrane filter tank, and the addition amount of CO2 and the addition amount of coagulant in the coagulation sedimentation tank according to the CO2 real-time correction aeration amount and the coagulant real-time correction addition amount.

2. The control method of the high pH raw water purification system according to claim 1, characterized by, In S1, the first deviation relationship curve is obtained by taking high-pH raw water as simulated water sample I, exposing CO2 gas into the simulated water sample I, measuring the changes of the pH value and the CO2 aeration amount, and establishing the first deviation relationship curve between the pH value and the CO2 aeration amount; The second deviation relationship curve is obtained by taking the simulated water sample I, adding an aluminum salt coagulant into the simulated water sample I, measuring the changes of the turbidity and the coagulant addition amount, and establishing the second deviation relationship curve between the turbidity and the coagulant addition amount.

3. The control method of the high pH raw water purification system according to claim 2, characterized by, In S1, the CO2 average deviation coefficient is obtained by: According to formula (1), the CO2 average deviation coefficient is calculated; （1）； wherein, represents the average deviation coefficient of CO2; i represents the numerical 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, which is generally 7.5 ~ 9.0, and n is the lowest value after the pH value decreases, which is generally 6.0 ~ 7.0; N represents the number of times of measuring the pH value and the corresponding CO2 deviation aeration amount in the process of the pH value decreasing from i to n; represents the CO2 deviation aeration amount when the pH value is i, which is obtained through the first deviation relationship curve; represents the CO2 theoretical aeration amount when the pH value is i, which is obtained through the first theoretical relationship curve; The first theoretical relationship curve is obtained by taking the high-pH raw water purification system treated water as simulated water sample II, exposing CO2 gas into the simulated water sample II, measuring the changes of the pH value and the CO2 aeration amount, and establishing the first theoretical relationship curve between the pH value and the CO2 aeration amount.

4. The control method of the high pH raw water purification system according to claim 3, characterized by, In S1, the coagulant average deviation coefficient is obtained by: According to formula (2), the coagulant average deviation coefficient is calculated; （2）； wherein, represents the average deviation coefficient of coagulant; j represents the value of turbidity change in simulated water sample I, j is from high to low, the initial value of j is the initial turbidity value of simulated water sample I, generally 20.0 ~ 25.0, m is the minimum value after turbidity decreases, generally 0 ~ 1.0; M represents the number of times of measuring turbidity and corresponding coagulant dosage in the process of turbidity decreasing from j to m; represents the coagulant deviation dosage when the turbidity is j, which is obtained through the second deviation relationship curve; represents the coagulant theoretical dosage when the turbidity is j, which is obtained through the second theoretical relationship curve; The second theoretical relationship curve is obtained by taking the simulated water sample II, adding an aluminum salt coagulant into the simulated water sample II, measuring the changes of the turbidity and the coagulant addition amount, and establishing the second theoretical relationship curve between the turbidity and the coagulant addition amount.

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

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

7. The control method of the high pH raw water purification system according to claim 1, characterized by, The control method further comprises: S6: monitoring Al 3+ concentration of the effluent of the aerated activated carbon filter in real time, and if the Al 3+ concentration is 0.05-0.2 mg / L, the effluent of the aerated activated carbon filter is re-circulated to the coagulation sedimentation tank.

8. A high pH raw water purification system characterized by, The system comprises a coagulation sedimentation tank, an aeration activated carbon filter tank, an aeration membrane filter tank and an automatic control system; the automatic control system performs the steps of the control method according to any one of claims 1-7.

9. The high pH raw water treatment system of claim 8, wherein, The automatic control system comprises water quality online monitoring equipment, CO2 adding equipment, coagulant adding equipment and a feedback control system; The water quality online monitoring equipment is provided with water quality monitoring probes respectively installed at the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank, the outlet of the aeration activated carbon filter tank and the outlet of the aeration membrane filter tank; The CO2 adding equipment is provided with CO2 aeration ports respectively communicating with the coagulation sedimentation tank, the aeration activated carbon filter tank and the aeration membrane filter tank; The coagulant adding equipment is provided with a coagulant adding port communicating with the coagulation sedimentation tank; The feedback control system performs the steps of the control method according to any one of claims 1-7.

10. The high pH raw water treatment system of claim 9, wherein, The feedback control system comprises an information acquisition module, a data processing and analysis module and a feedback control module; The information acquisition module is used for receiving water quality data information of the water quality monitoring probes and feeding back the water quality data information to the data processing and analysis module; The data processing and analysis module receives data information of the information acquisition module, calculates and corrects the CO2 aeration amount and the coagulant addition amount; The feedback control module comprises a CO2 adding control submodule and a coagulant adding control submodule; The CO2 adding control submodule receives data information of the data processing and analysis module, controls the opening and closing of the CO2 aeration ports and the gas flow; The coagulant adding control submodule controls the opening and closing of the coagulant adding port and the coagulant addition flow.

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