A method of disinfecting a mine water treatment plant

Abstract

The application provides a mine water treatment station disinfection method, and belongs to the technical field of mine water treatment; the mine water treatment station disinfection method comprises the following steps: determining a disinfectant dosing point position, setting the dosing point of a sodium hypochlorite disinfectant on a conveying pipeline after a secondary treatment unit water outlet and before an ultrafiltration system water inlet, so that the disinfectant is fully mixed and contacted with secondary treatment effluent before entering the ultrafiltration system; online monitoring and intelligent control, setting an online water quality monitoring instrument at the secondary treatment unit water outlet, and calculating and automatically adding the disinfectant dosage. In the above scheme, the mine water treatment station disinfection method moves the sodium hypochlorite dosing point from the end of the ultrafiltration system to after the secondary treatment and before the ultrafiltration system, prolongs the disinfection contact time from several minutes in the traditional process, and cooperates with the controlled addition of sodium hypochlorite, so that the disinfection effect is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of mine water treatment technology, and in particular to a disinfection method for mine water treatment plants. Background Technology

[0002] Mine water is a large volume of water that flows into the ground during coal mining when it comes into contact with coal seams and rock strata. Its water quality is complex, typically containing suspended solids, colloidal particles, dissolved organic matter, reducing inorganic substances such as sulfides and ferrous ions, as well as various microorganisms. Direct discharge without effective treatment will cause serious pollution to the surrounding water environment. With the increasing national requirements for the comprehensive utilization of coal mine water resources, the reuse of treated mine water for underground production, dust suppression, fire fighting, and greening irrigation has become a basic requirement.

[0003] Currently, advanced mine water treatment processes typically employ a process of coagulation, sedimentation, filtration, ultrafiltration, and disinfection. The ultrafiltration system, as the core treatment unit, is responsible for removing suspended solids, colloids, bacteria, and large organic molecules. The disinfection unit, as the final stage, is responsible for killing residual pathogens in the water, ensuring that the effluent meets microbiological standards.

[0004] However, existing disinfection processes in mine water treatment plants generally suffer from unreasonable disinfectant dosing point placement. In conventional process designs, disinfectants such as sodium hypochlorite are typically added to the terminal pipeline after the ultrafiltration system's permeate. This results in insufficient effective contact time between the disinfectant and the water; the residence time of the water from the dosing point through subsequent pipelines to the outlet is often less than a few minutes, failing to meet the sufficient contact time required for sodium hypochlorite disinfection. Specifically, the bactericidal effect of sodium hypochlorite follows the CT value principle, which is the product of the disinfectant concentration C and the contact time T. When the contact time T is too short, even a significant increase in the dosing concentration C makes it difficult to achieve a stable disinfection effect. Furthermore, due to the complexity of the terminal pipeline system and the uneven flow pattern, the disinfectant's mixing uniformity in the water is poor, leading to fluctuations in the disinfection effect and making it difficult to consistently meet the standards for effluent microbial indicators. Therefore, this application proposes a disinfection method for mine water treatment plants. Summary of the Invention

[0005] This invention provides a disinfection method for mine water treatment plants, which solves the technical problems of insufficient disinfection contact time and unstable disinfection effect in traditional processes by optimizing the setting location and dosing control method of disinfectant dosing points.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A disinfection method for a mine water treatment plant includes: Determine the location of the disinfectant dosing point and set the sodium hypochlorite disinfectant dosing point on the delivery pipeline after the outlet of the secondary treatment unit and before the inlet of the ultrafiltration system, so that the disinfectant can be fully mixed and reacted with the secondary treatment effluent before entering the ultrafiltration system; Online monitoring and intelligent control: Online water quality monitoring instruments are installed at the outlet of the secondary treatment unit. The online water quality monitoring instruments include at least a flow meter, a turbidity meter, a pH meter, and an oxidation-reduction potential meter, which are used to collect water quality parameters such as influent flow rate Q, turbidity NTU, pH value, and oxidation-reduction potential ORP in real time. Disinfectant dosage calculation and automatic dosing: A PLC controller is used to calculate the amount of disinfectant to be added and control the metering pump to perform the dosing. Residual chlorine control in the produced water: After the water flows through the ultrafiltration system, it enters the produced water unit. The online residual chlorine analyzer detects the residual chlorine concentration in the produced water in real time and feeds it back to the PLC controller. When the residual chlorine concentration in the produced water exceeds the set range, the PLC controller automatically adjusts the output of the metering pump.

[0007] Optionally, in online monitoring and intelligent control, an online residual chlorine analyzer is installed at the ultrafiltration system's product water unit to detect the residual chlorine concentration C in the product water in real time. f The signal output terminals of the online water quality monitoring instrument and the online residual chlorine analyzer are both connected to the signal input terminal of the PLC controller; the signal output terminal of the PLC controller is connected to the frequency control terminal and the stroke control terminal of the metering pump, which is used to transport sodium hypochlorite solution from the storage tank to the dosing point.

[0008] Optionally, the disinfectant dosage calculation and automatic dosing process is as follows: Based on the influent flow rate Q and the set target dosage concentration C set Unit: mg / L, calculate the basic dosage D base : In the formula: ω is the effective chlorine mass fraction of the sodium hypochlorite solution, C set The range is 2–8 mg / L; The basic dosage was adjusted by feedforward based on the influent water quality parameters to obtain the adjusted dosage D. adj : In the formula: NTU0 is the reference turbidity value; ORP offset k1 is the redox potential shift coefficient, which takes a positive value when the measured ORP < 400 mV and a negative value when the ORP ≥ 400 mV; k2 is the turbidity correction coefficient, with a value ranging from 0.05 to 0.15; k3 is the ORP correction coefficient, with a value ranging from 0.002 to 0.008 mV. - ¹.

[0009] Then, based on the residual chlorine concentration C in the product waterf Feedback PID control is performed to obtain the final dosage D. final ; In the formula: e(t) = C target -C f C represents the deviation between the setpoint and the measured value of residual chlorine. target The target residual chlorine concentration is set within the range of 0.3–0.8 mg / L; K p For proportional gain, the value ranges from 0.5 to 2.0; K i The integral time constant ranges from 0.05 to 0.2 min. - ¹;K d is the differential time constant, with a value ranging from 0.01 to 0.05 min.

[0010] Optionally, C set The settings are differentiated based on the characteristics of mine water quality: When the COD of the secondary treated effluent Cr When ≤30 mg / L, C se t is taken as 2-4 mg / L; when 30 < COD Cr When ≤60 mg / L, C set Take 4–6 mg / L; when COD Cr When >60 mg / L, C set Take 6–8 mg / L.

[0011] Optionally, a static mixer is installed on the delivery pipeline after the outlet of the secondary treatment unit and before the inlet of the ultrafiltration system. The static mixer is located 1 to 3 m downstream of the sodium hypochlorite disinfectant dosing point.

[0012] Optionally, the length of the pipeline between the sodium hypochlorite disinfectant dosing point and the inlet of the ultrafiltration system shall not be less than 50m.

[0013] The beneficial effects of the above-described technical solution of the present invention are as follows: This application moves the sodium hypochlorite dosing point from the end of the ultrafiltration system to after the secondary treatment and before the ultrafiltration system, thus extending the disinfection contact time from several minutes in traditional processes. According to the CT value disinfection principle, the disinfection effect is a function of the disinfectant concentration and the contact time. Under the same dosing concentration, extending the contact time results in a proportional increase in the CT value, thereby improving the disinfection inactivation rate. Combined with controlled sodium hypochlorite dosing, the disinfection effect is significantly improved.

[0014] This application constructs a dual membrane protection mechanism of antibacterial and load-reducing properties, thereby lowering the risk of ultrafiltration membrane fouling. The added sodium hypochlorite pre-oxidizes and removes reducing substances from the water before it enters the ultrafiltration system, creating a continuous antibacterial environment on the ultrafiltration membrane surface. This effectively inhibits the attachment and reproduction of microorganisms on the membrane surface, ensuring the long-term stable and efficient operation of the water treatment system.

[0015] This application only requires moving the sodium hypochlorite dosing point forward and equipping it with an intelligent control system. The main treatment structures do not need to be newly built or renovated. With a small engineering investment, a systematic improvement in water quality safety, equipment maintenance and operating costs can be achieved. It is suitable for the renovation of existing mine water treatment plants, and the engineering renovation cost is small. Attached Figure Description

[0016] Figure 1 This is a flowchart of the disinfection method for mine water treatment stations according to the present invention. Detailed Implementation

[0017] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, an embodiment of the present invention provides a disinfection method for a mine water treatment station. The mine water treatment station includes at least a secondary treatment unit, an ultrafiltration system, and a product water unit connected in series. The membrane module of the ultrafiltration system is a hollow fiber ultrafiltration membrane with a molecular weight cutoff of 50–150 kDa. The operating mode is cross-flow filtration, and the transmembrane pressure difference is controlled within the range of 0.05–0.15 MPa. The disinfection method for this mine water treatment station includes: Determine the location of the disinfectant dosing point and place the sodium hypochlorite disinfectant dosing point on the delivery pipeline after the outlet of the secondary treatment unit and before the inlet of the ultrafiltration system. This ensures that the disinfectant is fully mixed and reacts with the secondary treatment effluent before entering the ultrafiltration system. The length of the delivery pipeline between the dosing point and the inlet of the ultrafiltration system should be no less than 50 meters to guarantee sufficient mixing and initial reaction time between the disinfectant and the water.

[0019] Online monitoring and intelligent control are implemented. Online water quality monitoring instruments, including at least a flow meter, turbidity meter, pH meter, and oxidation-reduction potential meter, are installed at the outlet of the secondary treatment unit to collect water quality parameters in real time, such as influent flow rate Q (m³ / h), turbidity NTU, pH value, and oxidation-reduction potential ORP (mV). An online residual chlorine analyzer is installed at the permeate unit of the ultrafiltration system to detect the residual chlorine concentration C in the permeate in real time. f (Unit: mg / L, calculated as free chlorine).

[0020] In this embodiment, the signal output terminals of both the online water quality monitoring instrument and the online residual chlorine analyzer are connected to the signal input terminal of the PLC controller. The signal output terminal of the PLC controller is connected to the frequency control terminal and the stroke control terminal of the metering pump, which is used to transport sodium hypochlorite solution from the storage tank to the dosing point. In this embodiment, the metering pump is a diaphragm metering pump with dual-mode control functions of frequency regulation and stroke regulation. The flow rate regulation range is 0–100 L / h, and the regulation accuracy is not less than ±1%. In addition, the online water quality monitoring instrument also includes a temperature sensor and a conductivity meter. The temperature sensor is used for temperature compensation of pH and ORP measurements, and the conductivity meter is used to monitor changes in the salinity of the influent.

[0021] Disinfectant dosage calculation and automatic dosing: The PLC controller calculates the disinfectant dosage and controls the metering pump to perform the dosing, as follows: First, based on the influent flow rate Q and the set target dosage concentration C... set (Unit: mg / L), calculate the basic dosage D base : In the formula: ω is the effective chlorine mass fraction (%) of the sodium hypochlorite solution, C set The range is 2–8 mg / L.

[0022] Secondly, the basic dosage is feedforward corrected based on the influent water quality parameters to obtain the corrected dosage D. adj : In the formula: NTU0 is the reference turbidity value (taken as 3 to 5 NTU); ORP offset k1 is the redox potential shift coefficient, which takes a positive value when the measured ORP < 400 mV and a negative value when the ORP ≥ 400 mV; k2 is the turbidity correction coefficient, with a value ranging from 0.05 to 0.15; k3 is the ORP correction coefficient, with a value ranging from 0.002 to 0.008 mV. - ¹.

[0023] Then, based on the residual chlorine concentration C in the product water f Feedback PID control is performed to obtain the final dosage D. final : In the formula: e(t) = C target -C f C represents the deviation between the setpoint and the measured value of residual chlorine. target The target residual chlorine concentration is set within the range of 0.3–0.8 mg / L; K p For proportional gain, the value ranges from 0.5 to 2.0; K i The integral time constant ranges from 0.05 to 0.2 min. - ¹;Kd is the differential time constant, with a value ranging from 0.01 to 0.05 min.

[0024] In this embodiment, feedforward correction and feedback PID regulation constitute a composite control strategy, wherein the response period of feedforward correction is 1 to 5 min / time, and the response period of feedback PID regulation is 10 to 30 s / time.

[0025] The role of disinfectant in an ultrafiltration system is as follows: After the added sodium hypochlorite disinfectant undergoes preliminary mixing and contact reaction with the water discharged from the secondary treatment in the delivery pipeline, the water carrying residual chlorine enters the ultrafiltration system. During the operation of the ultrafiltration system, sodium hypochlorite plays the following roles: Pre-oxidation: Residual reducing substances, including sulfides (S²⁺), remain in the water discharged after secondary treatment with sodium hypochlorite oxidation. - ), ferrous ions (Fe²⁺) + The oxidation reaction equation is as follows: S² - + 4ClO - → SO4² - + 4Cl - ; 2Fe² + + ClO - + 2H + → 2Fe³ + + Cl - + H2O; Pre-oxidation eliminates interference from reducing substances, providing a stable water quality foundation for subsequent disinfection; Antibacterial: Sodium hypochlorite forms a continuous antibacterial environment on the surface of the ultrafiltration membrane, inhibiting the attachment and reproduction of microorganisms on the membrane surface, reducing the content of extracellular polymers of proteins and polysaccharides in the filter cake layer, thereby effectively slowing down the growth rate of transmembrane pressure difference; Continuous disinfection: The entire process of water flowing through the ultrafiltration system constitutes effective disinfection contact time. The residence time of water in the ultrafiltration system is typically 15–45 minutes, allowing the CT value of the disinfectant to accumulate sufficiently, ensuring thorough disinfection. The formula for calculating the CT value is: In the formula: T total Let C(t) be the total hydraulic residence time of the water from the injection point to the outlet of the water production unit, and let C(t) be the function of the residual chlorine concentration along the flow path as a function of time.

[0026] Residual chlorine control in permeate water: After flowing through the ultrafiltration system, the water enters the permeate water unit. An online residual chlorine analyzer monitors the residual chlorine concentration in the permeate water in real time and feeds it back to the PLC controller. When the residual chlorine concentration exceeds the set range, the PLC controller automatically adjusts the output of the metering pump. In actual water treatment processes, when a reverse osmosis unit is installed, sodium bisulfite is added before the permeate water from the ultrafiltration system enters the reverse osmosis unit to reduce residual chlorine. The formula for calculating the sodium bisulfite dosage is: In the formula: D NaHSO3 The dosage of sodium bisulfite is given (unit: g / h); α is the reduction coefficient, with a value ranging from 2.5 to 3.5, meaning that approximately 3 mg of industrial sodium bisulfite is needed for 1 mg / L of residual chlorine to ensure that the residual chlorine in the reverse osmosis feed water is undetectable and the oxidation-reduction potential (ORP) is maintained within the range of 180±20 mV.

[0027] In this embodiment, a static mixer is installed on the delivery pipeline after the outlet of the secondary treatment unit and before the inlet of the ultrafiltration system. The static mixer is located 1 to 3 m downstream of the sodium hypochlorite disinfectant dosing point to enhance the mixing effect of the disinfectant and the water.

[0028] Furthermore, C set The settings are differentiated based on the characteristics of mine water quality: When the COD of the secondary treated effluent Cr When ≤30 mg / L, C se t is taken as 2-4 mg / L; when 30 < COD Cr When ≤60 mg / L, C set Take 4–6 mg / L; when COD Cr When >60 mg / L, C set Take 6–8 mg / L.

[0029] Furthermore, in this embodiment, when the transmembrane pressure difference of the ultrafiltration system exceeds a set threshold, an automatic backwashing program is initiated. The transmembrane pressure difference threshold of the ultrafiltration system can be set to 0.12 MPa. During the backwashing process, the sodium hypochlorite dosage is increased to 1.5 to 2.0 times the normal dosage, and the duration is 30 to 60 minutes, in order to enhance the bactericidal cleaning effect on the membrane surface.

[0030] This embodiment is further explained through the following specific implementation methods: Example 1: The project focuses on a mine water treatment plant with a treatment capacity of 5000 m³ / d. The raw water is the effluent from the mine inflow after secondary biological treatment, and the water quality indicators are: COD Cr The concentration was 45–55 mg / L, the turbidity was 5–8 NTU, the pH was 7.2–7.8, and the Fe²⁺ content was 45–55 mg / L. +Concentrations range from 1.2 to 2.5 mg / L, S² - The concentration is 0.3–0.8 mg / L. The original water treatment process uses a two-stage treatment process, including an ultrafiltration system, sodium hypochlorite dosing, and a product water tank. This process has problems such as short disinfection contact time, frequent ultrafiltration membrane fouling, and large fluctuations in the microbial indicators of the effluent.

[0031] Water treatment is performed according to the above implementation method: Relocation of the dosing point: The sodium hypochlorite dosing point is moved from the original ultrafiltration system's end-of-pipe pipeline to the downstream delivery pipeline of the secondary treatment unit's outlet. The length of the delivery pipeline between the relocated dosing point and the ultrafiltration system's inlet is approximately 65m, with a pipeline diameter of DN200. Based on a design flow rate of 5000 m³ / d, the hydraulic retention time of the water from the dosing point to the ultrafiltration system's inlet is approximately 5.8 min.

[0032] Install a static mixer: Install an SK-type static mixer 2 m downstream of the dosing point to enhance the mixing uniformity of sodium hypochlorite with the water.

[0033] Configure online monitoring instruments: Install an electromagnetic flow meter (accuracy ±0.5%), an online turbidity meter (range 0~100 NTU), an online pH meter (range 0~14), an online ORP meter (range -2000~+2000 mV), and a temperature sensor at the outlet of the secondary treatment unit. Install an online residual chlorine analyzer (range 0~5 mg / L, DPD colorimetric method principle, accuracy ±0.02 mg / L) on the ultrafiltration system's permeate pipeline.

[0034] An intelligent control system was established: a PLC was used as the core controller, equipped with a 7-inch touchscreen human-machine interface, and the sodium hypochlorite storage tank had a volume of 2 m³, using an industrial-grade sodium hypochlorite solution with an effective chlorine mass fraction ω=10%. A diaphragm metering pump was selected, with a maximum flow rate of 50 L / h, and features 4–20 mA analog signal input and dual frequency / stroke adjustment functions.

[0035] Control parameter settings: based on the COD of the mine water Cr For water quality conditions of 45–55 mg / L, the target dosage concentration C is set. set =5 mg / L, target residual chlorine concentration in product water C target =0.5 mg / L. Turbidity correction factor k1=0.10, ORP correction factor k2=0.005 mV - ¹. The PID parameter is: K p =1.2, K i =0.10 min - ¹, K d =0.02 min.

[0036] Operation process: After the system is put into operation, the PLC controller collects online monitoring data every 30 seconds, calculates and outputs control signals to the metering pump. The total hydraulic residence time of water flowing through the ultrafiltration system is about 22 minutes. Throughout the process, sodium hypochlorite continuously reacts with microorganisms and reducing substances in the water in the delivery pipeline and ultrafiltration membrane module.

[0037] Table 1 below shows a comparison of the parameters for the running results:

[0038] Example 2: The project focuses on a mine water treatment plant with a designed treatment capacity of 10,000 m³ / d. The water quality characteristics are high turbidity, high organic matter, and high COD. Cr The concentration is 65–85 mg / L, and the turbidity is 10–20 NTU. A reverse osmosis deep treatment unit is provided afterward.

[0039] Water treatment is performed according to the above implementation method: The dosing point is moved forward to the secondary treatment effluent pipeline, the delivery pipeline is about 80 m long, and the static mixer is installed 3 m downstream of the dosing point; Based on the characteristics of water with high organic matter, C set Set at 7 mg / L, C target The concentration was set to 0.6 mg / L. k1 was set to 0.15, with a larger correction margin due to the high turbidity. A sodium bisulfite dosing point is added between the ultrafiltration system's permeate pipeline and the reverse osmosis unit. A sodium bisulfite storage tank and metering pump are installed. The sodium bisulfite dosage is calculated based on a reduction coefficient α = 3.0. When the residual chlorine in the permeate is 0.6 mg / L, approximately 1.8 g of sodium bisulfite is added per cubic meter of permeate. The reverse osmosis feed water ORP is controlled at 180 ± 20 mV.

[0040] The ultrafiltration membrane uses a PVDF hollow fiber membrane with a molecular weight cutoff of 100 kDa. The transmembrane pressure difference is controlled within the range of 0.08–0.12 MPa. When the transmembrane pressure difference exceeds 0.12 MPa, the backwashing program is automatically triggered. During backwashing, the sodium hypochlorite dosage is increased to 12 mg / L and lasts for 40 min.

[0041] After adopting this implementation method, the disinfection contact time was extended from within 3 minutes before the modification to about 28 minutes, no coliform bacteria were detected in the effluent, the chemical cleaning cycle of the ultrafiltration membrane was extended, the cleaning cycle of the reverse osmosis membrane was extended, the consumption of sodium hypochlorite was reduced, and the stability of the disinfection effect, the operational reliability of the membrane system, and the efficiency of reagent utilization were all significantly improved.

[0042] Example 3: This embodiment provides the implementation process of the intelligent control algorithm in the disinfection method of a mine water treatment plant: Step 1: Data Acquisition and Preprocessing: The PLC controller continuously collects parameters such as influent flow rate Q, turbidity NTU, pH, ORP, and temperature T with a sampling period of 1 second. After removing measurement noise through moving average filtering, the control calculation is updated with a period of 30 seconds. Step 2: Feedforward correction calculation. Using the influent flow rate Q(t) and turbidity NTU(t) at the current time t as input, calculate the feedforward corrected dosage D. adj(t) : set up: Q(t) = 210 m³ / h; NTU(t) = 12 NTU; NTU_0 = 5 NTU; The measured value of ORP is 320 mV (below 400 mV, ORP_offset takes a positive value); C set =5 mg / L; ω=10%; k1=0.10; k2=0.005 mV - ¹.

[0043] Calculate the basic dosage: D base = 210 × 5 × (100 / 10) = 10500 mL / h; Calculate the turbidity correction term: k1 × (NTU - NTU0) / NTU0 = 0.10 × (12-5) / 5 = 0.14; ORP offset calculation: ORP base = (400-320) / 400 = 0.20, k2× ORP offset = 0.005 × 0.20 = 0.001.

[0044] Therefore: D adj = 10500 × (1 + 0.14 + 0.001) ≈ 11981 mL / h.

[0045] Step 3: Feedback PID control: The online residual chlorine analyzer detects the current residual chlorine concentration C in the product water. f =0.38 mg / L, target value C target =0.5 mg / L, deviation e(t)=0.12 mg / L.

[0046] PID control increment calculation: Proportional term: Kp × e(t) = 1.2 × 0.12 = 0.144 Integral term: K i × ∫e(t)dt ≈ 0.10 × 0.12 × 0.5 min = 0.006 Differential term: K d × de(t) / dt ≈ 0.02 × (0.12-0.09) / 0.5 = 0.0012 PID control coefficient = 1 + 0.144 + 0.006 + 0.0012 = 1.1512.

[0047] Step 4: Determine the final dosage: D final = D adj × 1.1512 ≈ 13792 mL / h. The PLC controller converts the calculated value into a 4-20 mA analog signal and outputs it to the metering pump. The metering pump adjusts its frequency and stroke accordingly to achieve precise dosing.

[0048] The above control algorithm is executed once every 30 seconds, and the feedforward correction updates the parameters every 3 minutes to ensure the system responds quickly and adjusts precisely to changes in water quality and quantity.

[0049] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A disinfection method for a mine water treatment station, characterized in that, include: Determine the location of the disinfectant dosing point and set the sodium hypochlorite disinfectant dosing point on the delivery pipeline after the outlet of the secondary treatment unit and before the inlet of the ultrafiltration system, so that the disinfectant can be fully mixed and reacted with the secondary treatment effluent before entering the ultrafiltration system; Online monitoring and intelligent control: Online water quality monitoring instruments are installed at the outlet of the secondary treatment unit. The online water quality monitoring instruments include at least a flow meter, a turbidity meter, a pH meter, and an oxidation-reduction potential meter, which are used to collect water quality parameters such as influent flow rate Q, turbidity NTU, pH value, and oxidation-reduction potential ORP in real time. Disinfectant dosage calculation and automatic dosing: A PLC controller is used to calculate the amount of disinfectant to be added and control the metering pump to perform the dosing. Residual chlorine control in the produced water: After the water flows through the ultrafiltration system, it enters the produced water unit. The online residual chlorine analyzer detects the residual chlorine concentration in the produced water in real time and feeds it back to the PLC controller. When the residual chlorine concentration in the produced water exceeds the set range, the PLC controller automatically adjusts the output of the metering pump.

2. The disinfection method for mine water treatment plants according to claim 1, characterized in that, In online monitoring and intelligent control, an online residual chlorine analyzer is installed at the ultrafiltration system's product water unit to detect the residual chlorine concentration C in the product water in real time. f The signal output terminals of the online water quality monitoring instrument and the online residual chlorine analyzer are both connected to the signal input terminal of the PLC controller; the signal output terminal of the PLC controller is connected to the frequency control terminal and the stroke control terminal of the metering pump, which is used to transport sodium hypochlorite solution from the storage tank to the dosing point.

3. The disinfection method for mine water treatment plants according to claim 1, characterized in that, The disinfectant dosage calculation and automatic dosing process are as follows: Based on the influent flow rate Q and the set target dosage concentration C set Unit: mg / L, calculate the basic dosage D base : In the formula: ω is the effective chlorine mass fraction of the sodium hypochlorite solution, C set The range is 2–8 mg / L; The basic dosage was adjusted by feedforward based on the influent water quality parameters to obtain the adjusted dosage D. adj : In the formula: NTU0 is the reference turbidity value; ORP offset k1 is the redox potential shift coefficient, which takes a positive value when the measured ORP < 400 mV and a negative value when the ORP ≥ 400 mV; k2 is the turbidity correction coefficient, with a value ranging from 0.05 to 0.15; k3 is the ORP correction coefficient, with a value ranging from 0.002 to 0.008 mV. - ¹. Then, based on the residual chlorine concentration C in the product water f Feedback PID control is performed to obtain the final dosage D. final ; In the formula: e(t) = C target - C f C represents the deviation between the setpoint and the measured value of residual chlorine. target The target residual chlorine concentration is set within the range of 0.3–0.8 mg / L; K p For proportional gain, the value ranges from 0.5 to 2.0; K i The integral time constant ranges from 0.05 to 0.2 min. - ¹;K d is the differential time constant, with a value ranging from 0.01 to 0.05 min.

4. The disinfection method for mine water treatment plants according to claim 3, characterized in that, C set The settings are differentiated based on the characteristics of mine water quality: When the COD of the secondary treated effluent Cr When ≤30 mg / L, C se t is taken as 2-4 mg / L; when 30 < COD Cr When ≤60 mg / L, C set Take 4–6 mg / L; when COD Cr When >60 mg / L, C set Take 6–8 mg / L.

5. The disinfection method for a mine water treatment station according to claim 1, characterized in that, A static mixer is installed on the delivery pipeline after the outlet of the secondary treatment unit and before the inlet of the ultrafiltration system. The static mixer is located 1 to 3 m downstream of the sodium hypochlorite disinfectant dosing point.

6. The disinfection method for a mine water treatment station according to claim 1, characterized in that, The length of the pipeline between the sodium hypochlorite disinfectant dosing point and the inlet of the ultrafiltration system shall not be less than 50 m.

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