Coagulation and sedimentation water treatment system and its control method

Abstract

This invention relates to the field of water treatment system technology, and in particular to a coagulation sedimentation water treatment system and its control method. By setting up a collection tank and multiple mixing tanks connected to the collection tank at the front of a baffle sedimentation tank, raw wastewater first flows into the collection tank to accumulate, serving as a transfer collection point before flowing into the mixing tanks. When coagulation treatment of the raw wastewater is required, the turbidity at the point near the first water pipe in the collection tank is obtained. Clear water from the end of the horizontal flow sedimentation tank and the raw wastewater from the collection tank are introduced into the mixing tank in a certain proportion, so that the raw wastewater is appropriately diluted to a predetermined turbidity range. Through aeration and temperature control, the wastewater in the mixing tank is adjusted to a preset temperature and pH range. Since the water in the mixing tank is no longer flowing, the amount of coagulant and coagulant aid added can be accurately quantified, thus avoiding the problem of difficulty in determining the dosage of coagulant and coagulant aid due to changes in multiple factors.

Description

Technical Field

[0001] This invention relates to the field of water treatment system technology, and in particular to a coagulation sedimentation water treatment system and its control method. Background Technology

[0002] The existing coagulation sedimentation water treatment system includes a mixing tank, a folded plate flocculation tank, a transition zone, and a horizontal flow sedimentation tank connected in sequence. Wastewater enters the mixing tank through the inlet pipe. The mixing tank is equipped with a coagulant dosing point, i.e., a stirring device. The wastewater and coagulant are fully mixed by a propeller mixer. The mixed water enters the folded plate flocculation zone through the inlet regulating plate to reduce the water flow velocity and prevent the flocs from breaking. Then it enters the transition zone and enters the horizontal flow sedimentation tank through the water distribution wall. The flocs begin to settle under the action of gravity. The clear water on the top flows into the air flotation tank at the rear end through the water collection tank.

[0003] In the above water treatment systems, the influent to the mixing tank is continuous, and the influent flow rate, turbidity, temperature, and pH are difficult to balance. Furthermore, the relationship between the amount of coagulant added and various influent indicators during coagulation and sedimentation is not linear. Therefore, it is difficult to accurately determine the amount of coagulant added to the mixing tank when multiple factors of influent indicators change. Existing technologies have disclosed techniques for training neural network models using datasets of influent indicators, coagulant addition amounts, and coagulation effects as training samples. These models attempt to summarize the weighted relationships between various influent indicators and coagulant addition amounts through neural network models, thereby predicting the amount of coagulant added. However, existing neural network models and algorithms still struggle to accurately predict the amount of coagulant added. This is because the flow of influent and effluent within the mixing tank affects the predicted amount of coagulant added due to the time series influence. Moreover, the amount of coagulant aid also affects the coagulation and sedimentation effect, making it difficult to accurately predict the amounts of both coagulant and coagulant aid.

[0004] The amount of coagulant and coagulant aid added has a great impact on the coagulation and sedimentation effect of water. Too little or too much addition will cause the coagulation and sedimentation effect to decrease. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a coagulation sedimentation water treatment system and its control method.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A coagulation sedimentation water treatment system includes a water collection tank, a mixing tank, a baffle flocculation tank, a transition zone, and a horizontal flow sedimentation tank;

[0008] The water collection tank is equipped with a sewage inlet at its beginning;

[0009] The number of mixing tanks is multiple, and each mixing tank is connected to the collection tank through a first water pipe. The collection tank is equipped with a first turbidity detection device near the first water pipe. Each first water pipe is connected to a first solenoid valve and a first flow meter. The mixing tank is equipped with a temperature sensor, a pH sensor, a heating device, an aeration device, a coagulant dosing device, and a coagulant aid dosing device.

[0010] Each mixing tank is connected to the baffle flocculation tank via a second water pipe. The second water pipe is connected to a second solenoid valve. The end of the baffle flocculation tank is connected to the transition zone. The transition zone is connected to the beginning of the horizontal flow sedimentation tank via a water distribution wall. A water collection trough is provided on the water surface at the end of the horizontal flow sedimentation tank. A third water pipe is connected to the end of the horizontal flow sedimentation tank near the water surface. The end of the third water pipe is connected to multiple branch water pipes via multi-port valves. The end of each branch water pipe is connected to each mixing tank. Each branch water pipe is connected to a third solenoid valve and a second flow meter.

[0011] It also includes a microprocessor, which is electrically connected to a first solenoid valve, a first flow meter, a first turbidity detection device, a temperature sensor, a pH sensor, a heating device, an aeration device, a coagulant dosing device, a coagulant aid dosing device, a second solenoid valve, a third solenoid valve, a multi-way valve, and a second flow meter.

[0012] Furthermore, in the above-mentioned coagulation sedimentation water treatment system, a liquid level sensor is installed in the water collection tank, and the liquid level sensor is electrically connected to the microprocessor.

[0013] Furthermore, in the above-mentioned coagulation sedimentation water treatment system, a second turbidity detection device is provided in the mixing tank, and the second turbidity detection device is electrically connected to the microprocessor.

[0014] Furthermore, in the above-mentioned coagulation sedimentation water treatment system, the mixing tank is also equipped with a stirring device, which is electrically connected to the untreated water.

[0015] This invention also protects a control method for the above-mentioned coagulation sedimentation water treatment system, comprising the following steps:

[0016] The first turbidity detection device obtains the turbidity value of the raw water near the first water pipe in the water collection tank. Based on the raw water turbidity value, it calculates the proportion of clean water required to dilute the raw water, so that the raw water and clean water are mixed in the calculated proportion to reach the preset turbidity range.

[0017] Based on the volume of the liquid level height sensed by the first liquid level sensor in the mixing tank, and the ratio of raw water to clean water, calculate the flow rates of raw water and clean water introduced into the mixing tank.

[0018] The first and third solenoid valves are opened to allow the raw water in the collection tank and the clear water in the horizontal sedimentation tank to be introduced into the mixing tank according to the calculated flow rate. When the first flow meter detects that the flow rate into the mixing tank reaches the calculated flow rate, the first solenoid valve is closed. When the second flow meter detects that the flow rate into the mixing tank reaches the calculated flow rate, the third solenoid valve is closed.

[0019] When the pH sensor detects that the pH value in the mixing tank is greater than the preset threshold, it controls the aeration device to turn on until the pH value is lower than the preset threshold, at which point it controls the aeration device to stop.

[0020] A temperature sensor acquires the water temperature in the mixing tank. When the water temperature is lower than a preset threshold, the heating device is turned on. When the water temperature in the mixing tank is higher than the preset threshold, the heating device is turned off.

[0021] Control the coagulant dosing device to turn on and add coagulant quantitatively into the mixing tank; control the coagulant aid dosing device to turn on and add coagulant aid quantitatively into the mixing tank.

[0022] After the coagulant and coagulant aid are added to the mixing tank and react for a preset time, the second solenoid valve is opened to allow the water in the mixing tank to be completely discharged into the baffle flocculation tank through the second water pipe. The water then enters the transition zone through the baffle flocculation tank and then enters the horizontal flow sedimentation tank through the water distribution wall.

[0023] Furthermore, in the control method of the above-mentioned coagulation sedimentation water treatment system, the specific calculation of the required proportion of clean water to dilute the raw water based on the turbidity value of the raw water is as follows:

[0024] Experiments were conducted on the mixing and dilution of raw water and clean water with different turbidity gradients. The required ratio of raw water to clean water when preparing mixed water with a preset turbidity was obtained through experiments. Linear regression was performed on multiple discrete mapping data of raw water and clean water mixing experiments with different turbidity gradients to obtain the functional relationship between raw water turbidity and mixing ratio.

[0025] The turbidity value obtained by the first turbidity sensor is substituted into the function to calculate the required proportion of clean water to dilute the raw water.

[0026] Furthermore, the control method for the above-mentioned coagulation sedimentation water treatment system also includes the step of controlling the stirring device to continuously stir.

[0027] Furthermore, in the control method of the above-mentioned coagulation sedimentation water treatment system, after the first solenoid valve and the third solenoid valve are closed, the method further includes the following steps: the second turbidity detection device detects the turbidity value of the water in the mixing tank, compares the detected turbidity value with the preset turbidity range, and opens the first solenoid valve or the third solenoid valve accordingly based on the comparison result to adjust the turbidity in the mixing tank until the turbidity in the mixing tank reaches the preset range, and then closes the first solenoid valve or the third solenoid valve.

[0028] Furthermore, in the control method of the above-mentioned coagulation sedimentation water treatment system, before the first turbidity detection device obtains the raw water turbidity value near the first water pipe in the collection tank, the method further includes the step of: the level sensor obtaining the liquid level in the collection tank, and controlling the opening of a corresponding number of first solenoid valves by the liquid level in the collection tank.

[0029] The beneficial effects of this invention are as follows: By setting up a collection tank and multiple mixing tanks connected to the collection tank at the front of the baffle sedimentation tank, the raw sewage first flows into the collection tank to collect, serving as a transfer collection before flowing into the mixing tank. When coagulation treatment of the raw sewage is required, the turbidity at the point near the first water pipe in the collection tank is obtained. The clean water at the end of the horizontal flow sedimentation tank and the raw sewage in the collection tank are introduced into the mixing tank in a certain proportion, so that the raw sewage is appropriately diluted to a predetermined turbidity range by the clean water. Through aeration and temperature control, the sewage in the mixing tank is adjusted to a preset temperature and pH range. During the mixing process in the mixing tank, the water in the mixing tank no longer flows, so the amount of coagulant and coagulant aid added can be accurately quantified. Since the turbidity, temperature, and pH of the water entering the mixing tank tend to be uniform each time, the amount of coagulant and coagulant aid added each time is the same. This avoids the problem of difficulty in determining the amount of coagulant and coagulant aid due to changes in multiple factors. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a coagulation sedimentation water treatment system according to a specific embodiment of the present invention;

[0031] Figure 2 This is a structural block diagram of a water collection tank in a coagulation sedimentation water treatment system according to a specific embodiment of the present invention;

[0032] Figure 3 This is a structural block diagram of a mixing tank in a coagulation sedimentation water treatment system according to a specific embodiment of the present invention;

[0033] Label Explanation:

[0034] 1. Water collection tank; 11. First turbidity detection device; 12. Liquid level sensor;

[0035] 2. Mixing tank; 21. First water pipe; 22. First solenoid valve; 23. First flow meter; 24. Second turbidity detection device; 25. Temperature sensor; 26. pH sensor; 27. Heating device; 28. Aeration device; 29. ​​Coagulant dosing device; 210. Coagulant aid dosing device;

[0036] 3. Folding plate flocculation tank; 31. Second water pipe; 32. Second solenoid valve;

[0037] 4. Transition zone;

[0038] 5. Horizontal flow sedimentation tank; 51. Third water pipe; 52. Multi-way valve; 53. Water distribution pipe; 54. Third solenoid valve; 55. Second flow meter. Detailed Implementation

[0039] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0040] Please refer to Figures 1 to 3 The present invention relates to a coagulation sedimentation water treatment system, including a water collection tank 1, a mixing tank 2, a baffle flocculation tank, a transition zone 4, and a horizontal flow sedimentation tank 5.

[0041] The water collection tank 1 is equipped with a sewage inlet at its beginning;

[0042] There are multiple mixing tanks 2, and each mixing tank 2 is connected to the collection tank 1 through a first water pipe 21. The collection tank 1 is equipped with a first turbidity detection device 11 near the first water pipe 21. Each first water pipe 21 is connected to a first solenoid valve 22 and a first flow meter 23. The mixing tank 2 is equipped with a temperature sensor 25, a pH sensor 26, a heating device 27, an aeration device 28, a coagulant dosing device 29, and a coagulant aid dosing device 210.

[0043] Each mixing tank 2 is connected to the baffle flocculation tank 3 via a second water pipe 31. The second water pipe 31 is connected to a second solenoid valve 32. The end of the baffle flocculation tank 3 is connected to the transition zone 4. The transition zone 4 is connected to the beginning of the horizontal flow sedimentation tank 5 via a water distribution wall. A water collection trough is provided on the water surface at the end of the horizontal flow sedimentation tank 5. A third water pipe 51 is connected to the end of the horizontal flow sedimentation tank 5 near the water surface. The end of the third water pipe 51 is connected to multiple branch water pipes 53 via a multi-way valve 52. The end of each branch water pipe 53 is connected to each mixing tank 2. Each branch water pipe 53 is connected to a third solenoid valve 54 and a second flow meter 55.

[0044] It also includes a microprocessor, which is electrically connected to the first solenoid valve 22, the first flow meter 23, the first turbidity detection device 11, the temperature sensor 25, the pH sensor 26, the heating device 27, the aeration device 28, the coagulant dosing device 29, the coagulant aid dosing device 210, the second solenoid valve 32, the third solenoid valve 54, the multi-way valve 52, and the second flow meter 55.

[0045] The control method for the above-mentioned coagulation sedimentation water treatment system includes the following steps:

[0046] The first turbidity detection device 11 acquires the turbidity value of the raw water near the first water pipe 21 in the water collection tank 1. Based on the turbidity value of the raw water, it calculates the proportion of clean water required to dilute the raw water, so that the raw water and clean water are mixed in the calculated proportion to reach the preset turbidity range.

[0047] Based on the volume of the liquid level height sensed by the first liquid level sensor 12 in the mixing tank 2, and the ratio of raw water to clean water, calculate the flow rates of raw water and clean water introduced into the mixing tank 2.

[0048] The first solenoid valve 22 and the third solenoid valve 54 are opened to allow the raw water in the collection tank 1 and the clear water in the horizontal sedimentation tank 5 to be introduced into the mixing tank 2 according to the calculated flow rate. When the first flow meter 23 detects that the flow rate to the mixing tank 2 has reached the calculated flow rate, the first solenoid valve 22 is closed. When the second flow meter 55 detects that the flow rate to the mixing tank 2 has reached the calculated flow rate, the third solenoid valve 54 is closed.

[0049] When the pH sensor 26 detects that the pH value in the mixing tank 2 is greater than the preset threshold, it controls the aeration device 28 to turn on until the pH value is lower than the preset threshold, at which point it controls the aeration device 28 to stop.

[0050] Temperature sensor 25 acquires the water temperature in mixing tank 2. When the water temperature is lower than the preset threshold, it controls the heating device 27 to turn on. When the water temperature in mixing tank 2 is higher than the preset threshold, it controls the heating device 27 to turn off.

[0051] The coagulant dosing device 29 is turned on to add coagulant quantitatively into the mixing tank 2, and the coagulant aid dosing device 210 is turned on to add coagulant aid quantitatively into the mixing tank 2.

[0052] After the coagulant and coagulant aid are added to the mixing tank 2 and react for a preset time, the second solenoid valve 32 is opened, so that the water in the mixing tank 2 is completely discharged into the baffle flocculation tank 3 through the second water pipe 31. The water enters the transition zone 4 through the baffle flocculation tank 3, and then enters the horizontal flow sedimentation tank 5 through the water distribution flower wall.

[0053] In the above implementation method, the specific calculation of the required proportion of clean water to dilute the raw water based on the turbidity value of the raw water is as follows:

[0054] Experiments were conducted on the mixing and dilution of raw water and clean water with different turbidity gradients. The required ratio of raw water to clean water when preparing mixed water with a preset turbidity was obtained through experiments. Linear regression was performed on multiple discrete mapping data of raw water and clean water mixing experiments with different turbidity gradients to obtain the functional relationship between raw water turbidity and mixing ratio.

[0055] The turbidity value obtained by the first turbidity sensor is substituted into the function to calculate the required proportion of clean water to dilute the raw water.

[0056] Linear regression is a type of regression analysis that uses a least-squares function, called the linear regression equation, to model the relationship between one or more independent variables and a dependent variable. This function is a linear combination of one or more model parameters called regression coefficients. A case with only one independent variable is called simple regression. This example uses simple regression, where the independent variable is the raw water turbidity, and the dependent variable is the ratio of raw water to clean water required to dilute to a preset turbidity. The linear regression model is fitted using least-squares approximation to form a functional relationship between the independent and dependent variables. Since the volume of mixing tank 2 is a fixed value, by detecting the turbidity at the end of collection tank 1, clean water and wastewater are mixed in a relatively accurate ratio, ensuring that the mixed raw water reaches the preset turbidity range.

[0057] In a preferred embodiment, the water collection tank 1 is provided with a liquid level sensor 12, which is electrically connected to a microprocessor.

[0058] In the control method of the above-mentioned coagulation sedimentation water treatment system, before the first turbidity detection device 11 obtains the raw water turbidity value near the first water pipe 21 in the water collection tank 1, the method further includes the step of: the liquid level sensor 12 obtains the liquid level in the water collection tank 1, and controls the opening of a corresponding number of first solenoid valves 22 by the liquid level in the water collection tank 1.

[0059] In the above embodiments, the inflow of water into the collection tank 1 is not constant, but is caused by various factors such as season and rainfall. For example, when there are sudden events such as rainstorms or flood discharge, the inflow will increase significantly. The water level in the collection tank 1 needs to be controlled. The number of mixing tanks 2 that need to be discharged to at the same time can be selected according to the inflow of water into the collection tank 1 (the liquid level in the collection tank 1). For example, when four mixing tanks 2 are set, the raw water in the collection tank 1 is usually directed to two mixing tanks 2 for treatment at the same time. When the inflow increases and the liquid level in the collection tank 1 is higher than the preset threshold, water can be controlled to enter four mixing tanks 2 at the same time to speed up the treatment efficiency of the raw water and keep the water level in the collection tank 1 at a more reasonable height.

[0060] In a preferred embodiment, the mixing tank 2 is provided with a second turbidity detection device 24, which is electrically connected to a microprocessor.

[0061] In a preferred embodiment, the mixing tank 2 is further provided with a stirring device, which is electrically connected to the unprocessed material. The method also includes the step of controlling the stirring device to continuously stir.

[0062] In the control method of the above-mentioned coagulation sedimentation water treatment system, after the first solenoid valve 22 and the third solenoid valve 54 are closed, the method further includes the following steps: the second turbidity detection device 24 detects the turbidity value of the water in the mixing tank 2, compares the detected turbidity value with the preset turbidity range, and opens the first solenoid valve 22 or the third solenoid valve 54 accordingly based on the comparison result to adjust the turbidity in the mixing tank 2 until the turbidity in the mixing tank 2 reaches the preset range, and then closes the first solenoid valve 22 or the third solenoid valve 54.

[0063] In the above embodiments, since there will be a certain error when calculating the mixing ratio of sewage and raw water by means of linear regression each time the turbidity of the influent is measured, after the raw water and sewage are mixed evenly, the turbidity of the water in the mixing tank 2 is measured again by the second turbidity detection device 24, and the turbidity of the water is finely adjusted again to ensure that the turbidity of the water in the mixing tank 2 is uniform within the preset range. This allows the dosage of coagulant and coagulant aid to be more accurately quantified.

[0064] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A control method of a coagulation sedimentation water treatment system, characterized by, The system comprises a water collecting pool, a mixing pool, a folded plate flocculation pool, a transition zone and a horizontal flow sedimentation pool. The water collecting pool is provided with a sewage inlet at the beginning end. The mixing pool is provided with a temperature sensor, a pH sensor, a heating device, an aeration device, a coagulant feeding device and a coagulant aid feeding device. The mixing pool is provided with a temperature sensor, a pH sensor, a heating device, an aeration device, a coagulant feeding device and a coagulant aid feeding device. The mixing pool is provided with a temperature sensor, a pH sensor, a heating device, an aeration device, a coagulant feeding device and a coagulant aid feeding device. The system further comprises a microprocessor which is electrically connected with the first electromagnetic valve, the first flowmeter, the first turbidity detection device, the temperature sensor, the pH sensor, the heating device, the aeration device, the coagulant feeding device, the coagulant aid feeding device, the second electromagnetic valve, the third electromagnetic valve, the multi-way valve and the second flowmeter. The method comprises the following steps: The first turbidity detection device obtains the turbidity value of the raw water near the first water pipe of the water collecting pool, and calculates the proportion of the clean water needed to dilute the raw water according to the turbidity value of the raw water, so that the diluted raw water and the clean water are mixed according to the calculated proportion to reach the preset turbidity range. According to the volume of the liquid level height sensed by the first liquid level sensor in the mixing pool and the proportion of the raw water and the clean water, the flow of the raw water and the clean water introduced into the mixing pool is calculated. When the pH value in the mixing pool is greater than the preset threshold value, the aeration device is controlled to be opened until the pH value is lower than the preset threshold value, and the aeration device is controlled to be stopped. When the water temperature in the mixing pool is lower than the preset threshold value, the heating device is controlled to be turned on, and when the water temperature in the mixing pool is higher than the preset threshold value, the heating device is controlled to be turned off. The coagulant feeding device is controlled to be turned on to quantitatively feed the coagulant into the mixing pool, and the coagulant aid feeding device is controlled to be turned on to quantitatively feed the coagulant aid into the mixing pool. After the coagulant and the coagulant aid are fed into the mixing pool and react for a preset time, the second electromagnetic valve is controlled to be opened, so that the water in the mixing pool is completely discharged into the folded plate flocculation pool through the second water pipe, and the water enters the transition zone through the folded plate flocculation pool, and then enters the horizontal flow sedimentation pool through the water distribution flower wall.

2. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, The water collecting pool is provided with a liquid level sensor, and the liquid level sensor is electrically connected with the microprocessor.

3. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, The mixing pool is provided with a second turbidity detection device, and the second turbidity detection device is electrically connected with the microprocessor.

4. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, The mixing pool is further provided with a stirring device, and the stirring device is electrically connected with the microprocessor.

5. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, According to the turbidity value of the raw water, the proportion of clean water required for diluting the raw water is calculated, and the specific method is as follows: The mixing and dilution experiment of raw water and clean water with different turbidity gradients is carried out, the proportion of raw water and clean water required for preparing mixed water with a preset turbidity is obtained through the experiment, the function relationship between the turbidity of raw water and the mixing ratio is obtained through linear regression of multiple discrete mapping data of the experimental data of the mixing experiment of raw water and clean water with different turbidity gradients, and the turbidity value obtained by the first turbidity sensor is substituted into the function to calculate the proportion of clean water required for diluting the raw water. The stirring device is controlled to continuously stir.

6. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, After the first electromagnetic valve and the third electromagnetic valve are closed, the second turbidity detection device detects the turbidity value of the water in the mixing pool, compares the detected turbidity value with the preset turbidity range, and according to the comparison result, the first electromagnetic valve or the third electromagnetic valve is opened to adjust the turbidity in the mixing pool until the turbidity in the mixing pool reaches the preset range, and then the first electromagnetic valve or the third electromagnetic valve is closed.

7. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, Before the first turbidity detection device obtains the turbidity value of the raw water near the first water pipe in the water collecting pool, the liquid level sensor obtains the liquid level in the water collecting pool, and the corresponding number of first electromagnetic valves are opened by controlling the liquid level in the water collecting pool.

8. The control method of the coagulation sedimentation water treatment system according to claim 1, characterized by, ​

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