A pre-chlorination enhanced coagulation algae removal dosing system and refined intelligent control method

Abstract

A pre-chlorination enhanced coagulation algae removal dosing system and fine intelligent control method belong to the field of water treatment technology. The system includes raw water pump, tubular static mixer, flocculation tank, sedimentation tank, industrial computer and various online detectors to monitor flow, temperature, turbidity, characteristic fluorescence peak intensity, ultraviolet absorbance and organic matter concentration. Based on the integrated real-time sensing data, the characteristic fluorescence intensity ratio of algae cells before flocculation after pre-chlorination is monitored, and the dosing amount of oxidant (available chlorine) and coagulant is fine and intelligently controlled under the premise of ensuring the integrity of algae cells and enhanced coagulation. Under different water quality conditions, the system shows good self-adaptive ability, and uses dynamic adjustment algorithm to realize precise dosing of oxidant (available chlorine) and coagulant, ensuring the water quality and saving the drug consumption.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology and discloses a dosing system and a refined intelligent control method for pre-chlorination enhanced coagulation and algae removal in source water, particularly relating to the field of pre-oxidation enhanced coagulation and algae removal water treatment technology. Background Technology

[0002] Algal blooms have become an increasingly prominent ecological and environmental safety issue in lakes and rivers worldwide, posing a serious threat to drinking water safety and the sustainability of aquatic ecosystems. During algal blooms, algal pollutants in source water severely impact water quality and water treatment processes. In water treatment processes, the traditional coagulation-sedimentation process remains the primary means of removing algal cells and algal pollutants. However, due to the low specific density, high motility, morphological diversity, and negative surface charge of algal cells, they are difficult to remove effectively in the coagulation-sedimentation unit, leading to increased coagulant dosage, higher chemical costs, and potential secondary pollution from residual metal ions. Furthermore, algal cells exacerbate scaling in subsequent filtration units, shorten filter cycles, and increase backwashing frequency. Therefore, the traditional coagulation-sedimentation-sand filtration process is no longer sufficient to address the problem of algal blooms. Enhancement technologies for conventional water treatment processes should be developed to improve algal removal efficiency and ensure drinking water safety.

[0003] Enhanced algae removal technologies in drinking water treatment plants mainly include enhanced coagulation, pre-oxidation, flotation, electrochemical methods, and ultrasound. Considering overall decontamination efficiency, operating costs, operating environment, and engineering feasibility, chemical pre-oxidation is a widely used method in drinking water treatment plants to enhance conventional treatment processes. It primarily works by altering the surface characteristics and zeta potential of algal cells, destroying organic coatings, and inactivating algal cells, thereby enhancing the subsequent coagulation and algae removal effect. Chlorine-based oxidants (including liquid chlorine, sodium hypochlorite, chlorine dioxide, and bleaching powder) are widely used in water plants due to their low cost and high efficiency. However, regardless of the oxidant used, excessive dosage will lead to algal cell lysis and the release of intracellular organic matter (IOM). Low molecular weight and hydrophilic components in IOM are not only difficult to remove through coagulation but also easily form complexes with coagulants, increasing the amount of coagulant required. Therefore, appropriate pre-oxidation technology that maintains cell integrity and prevents IOM release is crucial for treating high-algae water. Moderate pre-oxidation desorbs S-AOM (attached organic matter) from the surface of algal cells, destabilizing and inactivating the algal cells without damaging their integrity, thereby enhancing coagulation and algae removal.

[0004] To address the shortcomings of traditional algal cell integrity assessment methods (such as scanning electron microscopy, fluorescence microscopy, and flow cytometry), including complex pretreatment, long analysis times, limitations in staining conditions, and the inability to perform real-time online monitoring in water treatment plants, the applicant has developed a dosing system and a refined intelligent control method based on the identification of characteristic fluorescent substances in algae. This method not only enables real-time online monitoring of algal cell integrity in water treatment plants but also determines the upper limit of oxidant dosage based on changes in raw water quality. To further improve the refined dosing control of oxidants and coagulants, there is an urgent need to develop an intelligent dosing system for pre-oxidation enhanced coagulation algae removal, ensuring effluent quality and achieving refined dosing of chemicals. This system will combine real-time sensing technology and data analysis to achieve precise dosing of oxidants and coagulants through intelligent control. Under adequate pre-oxidation conditions, this system can further optimize the pre-oxidation-coagulation treatment process to effectively address the increasingly severe challenges of treating algae-containing water sources. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a dosing system and a refined intelligent control method for pre-chlorination enhanced coagulation and algae removal in source water. This system not only achieves appropriate pre-oxidation by recognizing the structural integrity of algal cells, but also precisely controls the dosage of oxidants and coagulants based on changes in raw water quality conditions, ensuring the quality of drinking water supply and achieving precise dosing of chemicals.

[0006] The technical solution adopted by the system of the present invention is: a dosing system for prechlorination-enhanced coagulation and algae removal in source water, characterized in that:

[0007] Includes raw water pump (1), tubular static mixer (2), flocculation tank (3), sedimentation tank (4), flow meter (5), online temperature detector (6), online turbidity detector ① (7), online ultraviolet detector ① (8), online organic matter analyzer ① (9), oxidant tank (10), metering pump ① (11), metering pump ② (12), coagulant tank (13), online fluorescence detector (14), online turbidity detector ② (15), online ultraviolet detector ② (16), online organic matter analyzer ② (17), variable frequency speed controller ① (18), variable frequency speed controller ② (19), industrial computer (20);

[0008] The raw water pump (1), the tubular static mixer (2), the flocculation tank (3), and the sedimentation tank (4) are connected in series by pipelines, and the source water is sent into the tubular static mixer (2) through the raw water pump (1);

[0009] The flow meter (5), online temperature detector (6), online turbidity detector ① (7), online ultraviolet detector ① (8), and online organic matter analyzer ① (9) are installed on the raw water inlet pipe, and the online fluorescence detector (14) is installed on the inlet pipe of the flocculation tank (3); the online turbidity detector ② (15), online ultraviolet detector ② (16), and online organic matter analyzer ② (17) are installed on the outlet pipe of the sedimentation tank.

[0010] The oxidant tank (10) is connected to the tubular static mixer (2) via a metering pump ① (11) to add oxidant into the tubular static mixer (2). The oxidant can be a chlorine-based oxidant such as liquid chlorine, sodium hypochlorite, or bleaching powder; the coagulant tank (13) is connected to the tubular static mixer (2) via a metering pump ② (12) to add coagulant into the tubular static mixer (2). The coagulant can be an aluminum salt coagulant (polyaluminum chloride, aluminum sulfate, polyaluminum sulfate, etc.) or an iron salt coagulant (ferric chloride, ferrous sulfate, ferric sulfate, etc.);

[0011] The variable frequency speed controller ① (18) is electrically connected to the metering pump ① (11) for controlling the amount of oxidant added; the variable frequency speed controller ② (19) is electrically connected to the metering pump ② (12) for controlling the amount of coagulant added; the industrial computer (20) is electrically connected to the flow meter (5), the online temperature detector (6), the online turbidity detector ① (7), the online ultraviolet detector ① (8), the online organic matter analyzer ① (9), the online fluorescence detector (14), the online turbidity detector ② (15), the online ultraviolet detector ② (16), the online organic matter analyzer ② (17), the variable frequency speed controller ① (18), and the variable frequency speed controller ② (19), respectively.

[0012] The flow meter (5) monitors the raw water flow rate in real time, the online temperature detector (6) monitors the raw water temperature in real time, especially for monitoring the risk of algal blooms, the online turbidity detector ① (7) monitors the raw water turbidity in real time, and the online ultraviolet detector ① (8) monitors the raw water ultraviolet absorbance (UV) in real time. 254 The online organic matter analyzer ① (9) monitors the concentration of dissolved organic carbon (DOC) in the raw water in real time, and the online fluorescence detector (14) simultaneously detects the characteristic fluorescent substances released after algal cell membrane damage and the characteristic peak fluorescence intensity of humic substances related to natural organic matter. The data collected above are transmitted to the industrial control computer (20), the online turbidity detector ② (15) monitors the turbidity of the precipitated water in real time, and the online ultraviolet detector ② (16) monitors the ultraviolet absorbance (UV) of the precipitated water in real time. 254 The online organic matter analyzer ② (17) monitors the concentration of dissolved organic carbon (DOC) in the precipitated water in real time, and the industrial control computer (20) automatically adjusts the dosage of the reagent according to the preset algorithm.

[0013] The flocculation tank (3) can be a mechanical reaction flocculation tank or a hydraulic reaction flocculation tank, such as a baffle reaction flocculation tank, a perforated plate reaction flocculation tank, a corrugated plate reaction flocculation tank, etc. The hydraulic residence time of the flocculation tank is 15 to 20 minutes, and the average velocity gradient is controlled at 20 to 50 seconds. -1 The sedimentation tank (4) can be an inclined plate sedimentation tank, an inclined tube sedimentation tank, or a horizontal flow sedimentation tank.

[0014] The technical solution adopted in this invention is: a refined intelligent control method for a dosing system for pre-chlorination enhanced coagulation and algae removal, characterized in that:

[0015] The aim is to integrate multiple online detection instruments to monitor key water quality parameters in real time, and combine intelligent algorithms to dynamically adjust the dosage of oxidants and coagulants, thereby achieving precise control of the prechlorination and coagulation processes and efficiently removing algae and organic pollutants.

[0016] This method is applicable to an algal density of 10. 3 Up to 10 6 The water source contains cells per mL, with dominant algae species including cyanobacteria, green algae, and diatoms. When the water temperature is between 20°C and 30°C, the algal reproduction rate accelerates significantly. By monitoring data from a temperature detector, the possibility of algal blooms can be predicted in a timely manner, and the dosing strategies for secondary oxidants and coagulants can be adjusted accordingly.

[0017] The intelligent control method of the present invention is applicable to UV. 254 ≤0.1cm - 1. Raw water with DOC ≤ 2.5 mg / L and turbidity < 40 NTU was monitored in real time using an online ultraviolet detector, an online organic matter analyzer, and an online turbidity detector, and integrated into the industrial control computer system.

[0018] Through real-time data feedback and intelligent algorithm integration, the dosage of oxidant (chlorine) and coagulant (aluminum salt, iron salt) can be intelligently controlled respectively;

[0019] (1) Determine the upper limit of the oxidant (chlorine) concentration and at the same time determine the corresponding chlorine concentration during actual operation: Through the data feedback of the online temperature detector, especially when the water temperature is between 20℃ and 30℃, the system determines that algae may bloom and the pre-oxidant needs to be adjusted; the chlorine dosage is dynamically adjusted according to the change of the fluorescence intensity ratio C1 / C2. The fluorescence intensity of C1 and C2 is detected online by the online fluorescence detector. C1 is the characteristic fluorescent substance released after the algal cell membrane is damaged (this is detected by the online fluorescence detector (14)), and C2 represents the humic substances related to natural organic matter (also detected by the online fluorescence detector (14)).

[0020] The oxidant (chlorine) is first added using a time series model that segments the time step by step. The time points or time sequence of the addition are recorded as i = 0, 1, 2, 3...n (n≥3), and the specific value of n can be designed according to the needs.

[0021] The concentration of the oxidant (chlorine) added at the above n time points or moments (the concentration added to the pipeline) meets the following constraint: the chlorine concentration variation range meets 0.2 mg / L ≤ |m i+1 -m i |≤0.5mg / L, and 0.3mg / L≤m i ≤3.0 mg / L; preferably, the concentration of the oxidant (chlorine) gradually increases;

[0022] Chlorine dosing employs an hourly segmented time series model, based on the raw water flow rate Q at dosing time point i or moment i. i and chlorine concentration m in the pipeline i The design dynamically adjusts the speed of the oxidant metering pump to regulate the flow rate q of the chlorine dosing pump at specific times. i q i It is the volumetric flow rate of the chemical (usually expressed in L / h or m³). 3 / h represents), and the calculation formula is shown in (1); Q i The raw water flow rate at time i (in m³) 3 / h indicates); m i ρi is the chlorine concentration in the pipeline at any given time (expressed in mg / L); ρ0 is the effective concentration of the oxidant in the tank (expressed in g / L or kg / m2). 3 express).

[0023]

[0024] In the time series i = 0, 1, 2, 3...n (n≥3), the chlorine concentration at each time point is m. i The raw water flow rate is Q. i The corresponding chlorine dosing pump flow rate is q. i ;

[0025] The rate of change of the fluorescence intensity ratio C1 / C2 is calculated as shown in formula (2):

[0026]

[0027] (C1 / C2) i The ratio of fluorescence intensity at time i is C1 / C2; when the value of k in formula (2) reaches its maximum at time i and C1 i+1 >C1 i At that time, the upper limit concentration of chlorine is m i In actual, stable operation in the later stages is based on the chlorine concentration m at time i-1. i-1 The actual adjusted flow rate of the dosing pump is q.i-1 When the value of k in formula (2) reaches its maximum at time i and C1 i+1 <C1 i At that time, the upper limit concentration of chlorine is m i+2 The corresponding chlorine concentration m during the later actual operation i+1 The actual adjusted flow rate of the dosing pump is q. i+1 ;

[0028] (2) After determining the chlorine concentration corresponding to the actual operation in step (1), the fine-tuning of the coagulant dosage is determined based on the dissolved organic carbon (DOC) and ultraviolet absorbance (UV) in the water. 254 The dosage of coagulant is dynamically adjusted based on the removal efficiency of turbidity; when the UV of the raw water... 254 When the concentration of pollutants is ≤0.1 cm⁻¹, DOC ≤2.5 mg / L, and turbidity <40 NTU, the dosage of coagulant must meet the following requirements: the DOC removal rate of the effluent after settling reaches or exceeds 20% (i.e., the ratio of effluent DOC to influent DOC ≤80%), and the UV of the effluent after settling... 254 The removal rate should reach or exceed 35% (i.e., effluent UV). 254 With inlet UV 254 The ratio should be ≤65%, and the turbidity removal rate of the effluent after settling should reach or exceed 95% (i.e., the ratio of effluent turbidity to influent turbidity should be ≤5%), and the dosage of coagulant should be controlled within the range of 0.04 to 0.15 mM (calculated as Al or Fe).

[0029] After completing the time series optimization of oxidant (chlorine) dosage, the system automatically enters the next time series j = 0, 1, 2, 3...n (n≥1), where the specific value of n can be set as needed; and coagulants are added at different times j.

[0030] Based on the raw water flow rate Q j Adjust the coagulant metering pump speed according to the coagulant dosage, and adjust the coagulant dosing pump flow rate q at different times. j , is calculated using formula (3). Q j The raw water flow rate (in m³) at different times 3 / h indicates); m j ρ0 represents the concentration of coagulant in the pipeline at different times (expressed in mM, calculated as Al or Fe, the concentration added to the pipeline); w0 is the mass fraction of Al or Fe in the coagulant (expressed as %); and ρ0 is the effective concentration of the coagulant in the tank (expressed in g / L or kg / m³). 3 express).

[0031]

[0032] Initiate coagulant dosage optimization. The coagulant concentration at each time step is m. jThe raw water flow rate is Q. j The corresponding coagulant dosing pump flow rate is q. j At different times, the effluent water quality meets the target requirements, DOC 出水j / DOC 进水j ≤80%, UV 254出水j / and UV 254进水j ≤65%, T 出水j / T 进水j When the concentration is ≤5%, the system automatically optimizes the coagulant dosage to m at time j. j And adjust the dosing pump flow rate to the corresponding q. j To achieve the optimal dosage of coagulant;

[0033] (3) Under the conditions corresponding to steps (1) and (2) of maintaining the raw water quality, the actual operation is carried out according to the chlorine concentration determined in step (1) and the coagulant dosage determined in step (2).

[0034] (4) Time series triggering mechanism based on raw water quality fluctuations: When the system monitors the changes in raw water quality in real time and compares it with the raw water quality at time i=0 in step (1), if the change in any of the following indicators exceeds the preset threshold, then the next time series will be automatically started again in steps (1)-(3) to re-optimize the chlorine and coagulant dosing strategy: turbidity change exceeds 3 NTU, DOC change exceeds 0.2 mg / L, UV... 254 Changes exceeding 0.005cm - 1

[0035] (5) By designing and implementing the automatic control method based on fluorescence intensity ratio and water quality parameters in steps (1)-(4) above, it is embedded into the industrial control computer system for centralized control. The system logic control diagram is as follows: Figure 2 As shown, the system collects water quality information in real time and precisely adjusts the dosage of oxidant (chlorine) and coagulant based on the above-mentioned intelligent control method.

[0036] This system not only significantly improves the precision and efficiency of water treatment, but also adaptively adjusts to instantaneous changes in water quality, thereby optimizing reagent dosing, reducing the amount of chemical reagents used, and lowering treatment costs. Through the organic combination of the above-mentioned multi-parameter online monitoring and intelligent control algorithm, this invention achieves optimal performance at an algae density of 10... 3 Up to 10 6 cells / mL, UV 254 Under raw water conditions of ≤0.1cm-1, DOC≤2.5mg / L, and turbidity<40NTU, it can achieve efficient removal of algae and organic matter, ensuring the stability and efficiency of the water treatment process.

[0037] The beneficial effects of this invention are as follows:

[0038] The refined intelligent dosing system of this invention employs a dynamic control algorithm based on the intensity ratio of characteristic fluorescence peaks and integrates multi-parameter sensors for online water temperature, turbidity, ultraviolet light, and organic matter analysis. Through real-time data feedback combined with intelligent algorithms, it can precisely control the dosage of oxidants (chlorine) and coagulants (such as aluminum and iron salts) while ensuring adequate pre-oxidation. This significantly reduces the amount of chemicals used, lowers chemical costs, and simultaneously improves the removal efficiency of algae and organic matter, ensuring the stability and safety of the effluent quality. Furthermore, the intelligent control system possesses excellent adaptive capabilities, enabling rapid response to instantaneous changes in water quality and optimizing the dosing strategy. This characteristic makes the water treatment process more efficient and energy-saving, ensuring stable and efficient operation of the water treatment plant during algae blooms. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the process flow and control system of the invention.

[0040] 1-Raw water pump; 2-Pipeline static mixer; 3-Flocculation tank; 4-Sedimentation tank; 5-Flow meter; 6-Online temperature detector; 7-Online turbidity detector ①; 8-Online ultraviolet detector ①; 9-Online organic matter analyzer ①; 10-Oxidant tank; 11-Metering pump ①; 12-Metering pump ②; 13-Coagulant tank; 14-Online fluorescence detector; 15-Online turbidity detector ②; 16-Online ultraviolet detector ②; 17-Online organic matter analyzer ②; 18-Variable frequency speed controller; 19-Variable frequency speed controller ②; 20-Industrial control computer

[0041] Figure 2 This is the logic control diagram of the control system of the invention. Detailed Implementation

[0042] The pre-chlorination enhanced coagulation algae removal system and refined intelligent control method of this invention have been practically applied to the source water of three different water plants. The innovation and superiority of the system and method are ultimately demonstrated by the control of algal cell integrity and the improvement of post-sedimentation water quality. The invention is described in detail through the following examples; these embodiments are only a part of the embodiments of this invention, and not all of them.

[0043] Example 1:

[0044] The algae density in the water source of Water Plant A is 4.0 × 10⁻⁶. 4 Cells / mL, cyanobacteria, green algae, and diatoms were the dominant algal species, water temperature was 25±1℃, turbidity was 12±1 NTU, pH was 7.8±0.2, DOC was 2.0±0.2 mg / L, UV... 254 It is 0.087±0.005cm -1During the prechlorination process, a chlorine addition time sequence was set (i = 0, 1, 2, 3...7 (n = 7)), and the chlorine addition amount corresponding to each time point was m. i The concentrations were 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mg / L, respectively. The change in chlorine dosage between adjacent time points in this control system satisfies 0.2 ≤ |m i+1 -m i The concentration of chlorine is within the range of ≤0.5, and the chlorine dosage does not exceed 3.0 mg / L. The chlorine dosage is adjusted based on the change rate k of the fluorescence intensity ratio C1 / C2. Online data analysis shows that the dosage reaches its maximum when k is 0.236, at which point the fluorescence intensity at time i+2 is 6, and the fluorescence intensity C15 > C14 (C1...). i+1 >C1 i Therefore, the upper limit of chlorine dosage is m4, i.e., 1.5 mg / L. Adjust the chlorine dosage to m3, i.e., 1.2 mg / L. According to the preset algorithm conditions, the coagulant dosage must meet the following requirements: the DOC removal rate of the effluent after settling should reach or exceed 20% (i.e., the ratio of effluent DOC to influent DOC ≤ 80%), and the UV of the effluent after settling should be... 254 The removal rate should reach or exceed 35% (i.e., effluent UV). 254 With inlet UV 254 The ratio of turbidity to influent turbidity should be ≤65%, and the turbidity removal rate of the settled water should reach or exceed 95% (i.e., the ratio of effluent turbidity to influent turbidity ≤5%). The coagulant dosage should be controlled within the range of 0.04 to 0.15 mM (calculated as Al or Fe). Through adaptive adjustment, the intelligent system adjusts the coagulant dosage to 0.09 mM (calculated as Al). At this point, the turbidity removal rate of the settled water reaches 95.7%, the DOC removal rate is 22.6%, and the UV removal rate is [missing information]. 254 The removal rate reached 35.5%. Compared with traditional coagulation treatment processes, the turbidity removal rate increased by 13.5 percentage points, the DOC removal rate increased by 6.5 percentage points, and the UV removal rate increased by [missing percentage]. 254 The removal rate increased by 8.9 percentage points, and the amount of coagulant added was reduced by 50%. Water Plant A simultaneously achieved the goal of moderate pre-oxidation to enhance coagulation and save on chemical consumption.

[0045] Implementation Example 2:

[0046] The algae density in the water source of Water Plant B is 3 × 10⁻⁶. 3 Cells / mL, cyanobacteria and diatoms were the dominant algal species, water temperature was 22±2℃, turbidity was 5.0±0.5 NTU, pH was 7.5±0.1, DOC was 1.4±0.1 mg / L, UV... 254 It is 0.035±0.005cm -1During the prechlorination process, a chlorine addition time sequence was set (i = 1, 2, 3...7 (n = 7)), and the chlorine addition amount corresponding to each time point was m. i The concentrations were 0, 0.3, 0.6, 0.9, 1.2, 1.5, and 1.8 mg / L, respectively. The variation in chlorine dosage between adjacent time points in this control system satisfies 0.2 ≤ |m i+1 -m i The concentration of chlorine is within the range of ≤0.5, and the chlorine dosage does not exceed 3.0 mg / L. The chlorine dosage is adjusted based on the change rate k of the fluorescence intensity ratio C1 / C2. Online data analysis shows that the dosage reaches its maximum when k is 0.377, at which point the (i+2)th time step is 6, and the fluorescence intensity C15 > C14 (C1...). i+1 >C1 i Therefore, the upper limit of chlorine dosage is m4, i.e., 0.9 mg / L. Adjust the chlorine dosage to m3, i.e., 0.6 mg / L. According to the preset algorithm conditions, the coagulant dosage must meet the following requirements: the DOC removal rate of the effluent after settling should reach or exceed 20% (i.e., the ratio of effluent DOC to influent DOC ≤ 80%), and the UV of the effluent after settling should be... 254 The removal rate should reach or exceed 35% (i.e., effluent UV). 254 With inlet UV 254 The ratio of turbidity to influent turbidity should be ≤65%, and the turbidity removal rate of the settled water should reach or exceed 95% (i.e., the ratio of effluent turbidity to influent turbidity ≤5%). The coagulant dosage should be controlled within the range of 0.04 to 0.15 mM (calculated as Al or Fe). Through adaptive adjustment, the intelligent system adjusts the coagulant dosage to 0.06 mM (calculated as Al). At this point, the turbidity removal rate of the settled water reaches 97.3%, the DOC removal rate is 22.7%, and the UV removal rate is [missing information]. 254 The removal rate reached 39.1%. Compared with traditional coagulation treatment processes, the turbidity removal rate increased by 11.3 percentage points, the DOC removal rate increased by 7.9 percentage points, and the UV removal rate increased by [missing percentage]. 254 The removal rate increased by 10.9 percentage points, and the amount of coagulant added was reduced by 44%. Water Plant B also achieved the goal of moderate pre-oxidation to enhance coagulation and save on chemical consumption.

[0047] Implementation Example 3:

[0048] The algae density in the water source of Water Plant C is 1.5 × 10⁻⁶. 4 Cells / mL, diatoms were the dominant algal species, water temperature was 20±2℃, turbidity was 12.0±0.5 NTU, pH was 7.2±0.1, DOC was 1.5±0.1 mg / L, UV... 254 It is 0.038±0.005cm -1During the prechlorination process, a chlorine addition time sequence was set (i = 1, 2, 3...7 (n = 7)), and the chlorine addition amount corresponding to each time point was m. i The concentrations were 0, 0.3, 0.6, 0.9, 1.2, 1.5, and 1.8 mg / L, respectively. The variation in chlorine dosage between adjacent time points in this control system satisfies 0.2 ≤ |m i+1 -m i The concentration of chlorine is within the range of ≤0.5, and the chlorine dosage does not exceed 3.0 mg / L. The chlorine dosage is adjusted based on the change rate k of the fluorescence intensity ratio C1 / C2. Online data analysis shows that the dosage reaches its maximum when k is 0.587, at which point the fluorescence intensity at time i+2 is 4, and the fluorescence intensity C13 < C12 (C1...). i+1 <C1 i Therefore, the upper limit of chlorine dosage is m4, i.e., 0.9 mg / L. Adjust the chlorine dosage to m3, i.e., 0.6 mg / L. According to the preset algorithm conditions, the coagulant dosage must meet the following requirements: the DOC removal rate of the effluent after settling should reach or exceed 20% (i.e., the ratio of effluent DOC to influent DOC ≤ 80%), and the UV of the effluent after settling should be... 254 The removal rate should reach or exceed 35% (i.e., effluent UV). 254 With inlet UV 254 The ratio of turbidity to influent turbidity should be ≤65%, and the turbidity removal rate of the settled water should reach or exceed 95% (i.e., the ratio of effluent turbidity to influent turbidity ≤5%). The coagulant dosage should be controlled within the range of 0.04 to 0.15 mM (calculated as Al or Fe). Through adaptive adjustment, the intelligent system adjusts the coagulant dosage to 0.08 mM (calculated as Fe). At this point, the turbidity removal rate of the settled water reaches 97.2%, the DOC removal rate is 26.9%, and the UV removal rate is [missing information]. 254 The removal rate reached 40.8%. Compared with traditional coagulation treatment processes, the turbidity removal rate increased by 13.3 percentage points, the DOC removal rate increased by 8.8 percentage points, and the UV removal rate increased by [missing percentage]. 254 The removal rate increased by 13.9 percentage points, and the amount of coagulant added was reduced by 47%. Water Plant C also achieved the goal of moderate pre-oxidation to enhance coagulation and save on chemical consumption.

Claims

1. A method for precise and intelligent control of a dosing system for prechlorination-enhanced coagulation and algae removal in source water, characterized in that: The dosing system includes: a raw water pump (1), a tubular static mixer (2), a flocculation tank (3), a sedimentation tank (4), a flow meter (5), an online temperature detector (6), an online turbidity detector ① (7), an online ultraviolet detector ① (8), an online organic matter analyzer ① (9), an oxidant tank (10), a metering pump ① (11), a metering pump ② (12), a coagulant tank (13), an online fluorescence detector (14), an online turbidity detector ② (15), an online ultraviolet detector ② (16), an online organic matter analyzer ② (17), a variable frequency speed controller ① (18), a variable frequency speed controller ② (19), and an industrial computer (20). The raw water pump (1), the tubular static mixer (2), the flocculation tank (3), and the sedimentation tank (4) are connected in series by pipelines, and the source water is sent into the tubular static mixer (2) through the raw water pump (1); The flow meter (5), online temperature detector (6), online turbidity detector ① (7), online ultraviolet detector ① (8), and online organic matter analyzer ① (9) are installed on the raw water inlet pipe; the online fluorescence detector (14) is installed on the inlet pipe of the flocculation tank (3); the online turbidity detector ② (15), online ultraviolet detector ② (16), and online organic matter analyzer ② (17) are installed on the outlet pipe of the sedimentation tank. The oxidant tank (10) is connected to the tubular static mixer (2) via a metering pump ① (11) to add oxidant into the tubular static mixer (2); the oxidant is a chlorine-based oxidant; the coagulant tank (13) is connected to the tubular static mixer (2) via a metering pump ② (12) to add coagulant into the tubular static mixer (2); the coagulant is an aluminum salt coagulant or an iron salt coagulant; The variable frequency speed controller ① (18) is electrically connected to the metering pump ① (11) for controlling the amount of oxidant added; the variable frequency speed controller ② (19) is electrically connected to the metering pump ② (12) for controlling the amount of coagulant added; the industrial computer (20) is electrically connected to the flow meter (5), the online temperature detector (6), the online turbidity detector ① (7), the online ultraviolet detector ① (8), the online organic matter analyzer ① (9), the online fluorescence detector (14), the online turbidity detector ② (15), the online ultraviolet detector ② (16), the online organic matter analyzer ② (17), the variable frequency speed controller ① (18), and the variable frequency speed controller ② (19), respectively; The flow meter (5) monitors the raw water flow rate in real time, the online temperature detector (6) monitors the raw water temperature in real time, the online turbidity detector ① (7) monitors the raw water turbidity in real time, and the online ultraviolet detector ① (8) monitors the raw water ultraviolet absorbance (UV) in real time. 254 The online organic matter analyzer ① (9) monitors the concentration of dissolved organic carbon (DOC) in the raw water in real time, and the online fluorescence detector (14) simultaneously detects the characteristic fluorescent substances released after algal cell membrane damage and the characteristic peak fluorescence intensity of humic substances related to natural organic matter; the collected data is transmitted to the industrial control computer (20), the online turbidity detector ② (15) monitors the turbidity of the precipitated water in real time, and the online ultraviolet detector ② (16) monitors the ultraviolet absorbance (UV) of the precipitated water in real time. 254 ), the online organic matter analyzer ② (17) monitors the concentration of dissolved organic carbon (DOC) in the precipitated water in real time, and the industrial control computer (20) automatically adjusts the dosage of the reagent according to the preset algorithm; Intelligent control of the dosage of oxidant and coagulant is achieved through real-time data feedback and intelligent algorithm integration, including the following steps: (1) Determine the upper limit of chlorine concentration and the corresponding chlorine concentration during actual operation: Based on the data feedback from the online temperature detector, when the water temperature is between 20℃ and 30℃, the system determines whether algae bloom is possible and the pre-oxidant needs to be adjusted; the chlorine dosage is dynamically adjusted according to the change of the fluorescence intensity ratio C1 / C2. The fluorescence intensity of C1 and C2 is detected online by the online fluorescence detector. C1 is the characteristic fluorescent substance released after the algal cell membrane is damaged, and C2 represents humic substances related to natural organic matter. The oxidant is first added using a time series model that segments the time step by step. The time points or time sequence of the addition are denoted as i = 0, 1, 2, 3...n (n ≥ 3), and the specific value of n is designed according to the needs. The concentration of the oxidant added at the nth time point or moment satisfies the following constraint: the chlorine concentration variation range satisfies 0.2 mg / L ≤ | |≤0.5 mg / L, and 0.3 mg / L≤m i ≤3.0 mg / L; Chlorine dosing employs an hourly segmented time series model, based on the raw water flow rate Q at dosing time point i or moment i. i and chlorine concentration m in the pipeline i The design dynamically adjusts the speed of the oxidant metering pump to regulate the flow rate q of the chlorine dosing pump at specific times. i q i The volumetric flow rate of the added drug is usually expressed in L / h or m³. 3 / h represents the value, calculated as shown in formula (1); Q i The raw water flow rate at time i is expressed in m. 3 / h means; m i ρi is the chlorine concentration in the pipeline at any given time, expressed in mg / L; ρ0 is the effective concentration of the oxidant in the tank, expressed in g / L or kg / m2. 3 express; （1） In the time series i = 0, 1, 2, 3...n (n ≥ 3), the chlorine concentration at each time point is m. i The raw water flow rate is Q. i The corresponding chlorine dosing pump flow rate is q. i ; The rate of change of the fluorescence intensity ratio C1 / C2 is calculated as shown in formula (2): （2） This represents the fluorescence intensity ratio C1 / C2 at time i; when the value of k in formula (2) reaches its maximum at time i and C1 i+1 >C1 i At that time, the upper limit concentration of chlorine is m i In actual, stable operation in the later stages is based on the chlorine concentration m at time i-1. i-1 The actual adjusted flow rate of the dosing pump is q. i-1 When the value of k in formula (2) reaches its maximum at time i and C1 i+1 <C1 i At that time, the upper limit concentration of chlorine is m i+2 The corresponding chlorine concentration m during the later actual operation i+1 The actual adjusted flow rate of the dosing pump is q. i+1 ; (2) After determining the chlorine concentration corresponding to the actual operation in step (1), the fine-tuning of the coagulant dosage is then carried out: based on the dissolved organic carbon (DOC) and ultraviolet absorbance (UV) in the water. 254 The dosage of coagulant is dynamically adjusted based on the removal efficiency of turbidity; when the UV of the raw water... 254 ≤0.1 cm -1 When DOC ≤ 2.5 mg / L and turbidity < 40 NTU, the dosage of coagulant must meet the requirement that the DOC removal rate of the effluent after settling reaches or exceeds 20%, i.e., the ratio of effluent DOC to influent DOC ≤ 80%, and the UV of the effluent after settling... 254 The removal rate should reach or exceed 35% for UV removal in the effluent. 254 With inlet UV 254 The ratio should be ≤65%, and the turbidity removal rate of the effluent after settling should reach or exceed 95%, that is, the ratio of effluent turbidity to influent turbidity should be ≤5%, and the dosage of coagulant should be controlled within the range of 0.04 to 0.15 mM, calculated as Al or Fe. After completing the time series for optimizing the oxidant dosage, the system automatically enters the next time series j=0, 1, 2, 3...n (n≥1), where the specific value of n is set as needed; coagulant is added at different times j. Based on the raw water flow rate Q j Adjust the coagulant metering pump speed according to the coagulant dosage, and adjust the coagulant dosing pump flow rate q at different times. j Calculated using formula (3); Q j The raw water flow rate at different times is expressed in m. 3 / h means; m j ρj represents the concentration of coagulant in the pipeline at different times, expressed in mM, calculated as Al or Fe added to the pipeline; w0 represents the mass fraction of Al or Fe in the coagulant, expressed as %; and ρ0 represents the effective concentration of the coagulant in the tank, expressed in g / L or kg / m2. 3 express; or (3) Initiate coagulant dosage optimization; the coagulant concentration at each time step is m. j The raw water flow rate is Q. j The corresponding coagulant dosing pump flow rate is q. j At different times, the effluent water quality meets the target requirements, DOC 出水j / DOC 进水j ≤80%, UV 254出水j / UV 254进水j ≤65%, T 出水j / T 进水j When the concentration is ≤5%, the system automatically optimizes the coagulant dosage to m at time j. j And adjust the dosing pump flow rate to the corresponding q. j To achieve the optimal dosage of coagulant; (3) Under the conditions corresponding to steps (1) and (2) of maintaining the raw water quality, the actual operation is carried out according to the chlorine concentration determined in step (1) and the coagulant dosage determined in step (2); (4) Time series triggering mechanism based on raw water quality fluctuations: When the system monitors the changes in raw water quality in real time and compares it with the raw water quality at time i=0 in step (1), if the change in any of the following indicators exceeds the preset threshold, then the next time series will be automatically started again in steps (1)-(3), and the chlorine oxidant and coagulant dosing strategies will be re-optimized: turbidity change exceeds 3 NTU, DOC change exceeds 0.2 mg / L, UV 254 Changes exceeding 0.005 cm -1 ; (5) By designing and implementing the automatic control method based on fluorescence intensity ratio and water quality parameters in steps (1) to (4) above, the method is embedded into the industrial control computer system for centralized control; the system collects water quality information in real time and precisely adjusts the dosage of chlorine oxidant and coagulant based on the above intelligent control method.

2. The method according to claim 1, characterized in that, Step (1) The concentration of chlorine oxidant is gradually increased.

3. The method according to claim 1, characterized in that, Suitable for algae density of 10 3 Up to 10 6 cells / mL, UV 254 ≤0.1 cm -1 Raw water conditions: DOC ≤ 2.5 mg / L, turbidity < 40 NTU.

4. The method according to claim 1, characterized in that, The flocculation tank (3) is a mechanical reaction flocculation tank or a hydraulic reaction flocculation tank. The hydraulic residence time of the flocculation tank is 15-20 min, and the average velocity gradient is controlled at 20-50 s. -1 The sedimentation tank (4) is an inclined plate sedimentation tank, an inclined tube sedimentation tank, or a horizontal flow sedimentation tank.

5. The method according to claim 4, characterized in that, The flocculation tank (3) is a baffle plate reaction flocculation tank, a perforated plate reaction flocculation tank or a corrugated plate reaction flocculation tank.

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