Online monitoring device and method for high-concentration chloride ions in wastewater

Abstract

The invention relates to an online monitoring device for high-concentration chloride ions in wastewater, which comprises a water supply pump, a filter, a water inlet regulating valve, an overflow pool, a mixing pool, a detection pool, a wastewater peristaltic pump, a medicament peristaltic pump, a medicament bottle, a chloride ion concentration detector and a composite electrode, the water inlet end of the wastewater peristaltic pump is connected with the overflow pool, the water outlet end of the wastewater peristaltic pump is connected with the mixing pool, the water inlet end of the medicament peristaltic pump is connected with the medicament bottle, the water outlet end of the medicament peristaltic pump is connected with the mixing pool, the detection pool is communicated with the mixing pool, the composite electrode is mounted in the detection pool, and the signal output end of the composite electrode is connected with the chloride ion concentration detector. The invention also provides a monitoring method. According to the invention, suspended matters in water are removed by using the filter, and meanwhile, the chloride ion concentration detection range is expanded by using an ion strength correction method, so that the detection precision is greatly improved, and the detection and monitoring requirements of high-concentration chloride ions in wastewater can be met.

Description

Technical Field

[0001] The invention relates to the field of detection technology, in particular to online monitoring of chloride ions in waste water. Background Art

[0002] The concentration of chloride ions in water has an important impact on the safety and stability of industrial production processes and is an important determination index in water quality analysis. The upper limit detection concentration of chloride ions in existing industrial chloride ion online monitoring devices is about 3000mg / L. For example, the invention patent with publication number CN113447630A discloses a multi-parameter trace ion integrated online monitoring system, including an explosion-proof positive pressure cabinet, a monitoring system is provided in the explosion-proof positive pressure cabinet, and the monitoring system includes an iron ion monitoring module, a chloride ion monitoring module and a pH monitoring module, the iron ion monitoring module is used for the iron ion monitoring module, the chloride ion monitoring module is used to monitor chloride ions, and the pH monitoring module simultaneously displays pH value, temperature value, high point alarm setting value, low point alarm setting value, whether the instrument is in a high or low alarm state, and the current time, etc. Under the control of the automatic control system, the power distribution cabinet of the invention prevents flammable and dangerous gases from entering the positive pressure chamber, ensures the safe operation of ordinary instruments and electrical components installed inside, overcomes the corrosion of the equipment by the volatilization of corrosive gases in the open system, and the analyzer will automatically calibrate and clean using the built-in calibration standard solution and cleaning solution.

[0003] However, in some industrial production processes, there are wastewaters with chloride ion concentrations as high as 20,000 mg / L (such as desulfurization wastewater), and the wastewater has complex components and many interference factors in chloride ion detection, resulting in large measurement errors (generally greater than 30%) for high-concentration chloride ions in wastewater in existing online monitoring devices and methods, which cannot meet the requirements for rapid and accurate detection and monitoring of chloride ions in wastewater. Therefore, it is very necessary to design an online chloride ion monitoring device and method with a wide detection range and high detection accuracy. Summary of the invention

[0004] The purpose of the present invention is to provide an online monitoring device and method for high concentration chloride ions in wastewater in view of the drawbacks of the prior art, so as to improve the detection accuracy of chloride ion concentration in wastewater and meet the requirements of rapid and accurate detection and monitoring of high concentration chloride ions in wastewater.

[0005] The problem described in the present invention is solved by the following technical solution:

[0006] An online monitoring device for high-concentration chloride ions in wastewater comprises a water supply pump, a filter, a water inlet regulating valve, an overflow tank, a mixing tank, a detection tank, a wastewater peristaltic pump, a pharmaceutical peristaltic pump, a pharmaceutical bottle, a chloride ion concentration detector and a composite electrode. The water inlet pipe of the water supply pump is placed in the wastewater to be detected, the water outlet pipe is connected to the water inlet of the overflow tank through the filter and the water inlet regulating valve in sequence, the water inlet end of the wastewater peristaltic pump is connected to the overflow tank, and the water outlet end is connected to the mixing tank, the water inlet end of the pharmaceutical peristaltic pump is connected to the pharmaceutical bottle, and the water outlet end is connected to the mixing tank, the detection tank is connected to the mixing tank, the composite electrode is installed inside the detection tank, and the signal output end of the composite electrode is connected to the chloride ion concentration detector.

[0007] The above-mentioned online monitoring device for high concentration of chloride ions in wastewater also includes a backwash pump, a backwash water tank, a mixing tank backwash valve and a backwash main valve. The water inlet pipe of the backwash pump is connected to the backwash water tank, and the water outlet pipe is connected to the water inlet end of the water inlet regulating valve through the backwash main valve. The water inlet end of the mixing tank backwash valve is connected to the water outlet end of the water inlet regulating valve, and the water outlet end is connected to the mixing tank.

[0008] The above-mentioned online monitoring device for high concentration of chloride ions in wastewater also includes a DCS distributed control system and a computer, and the DCS distributed control system and the computer are connected to the chloride ion concentration detector via a communication cable or a wireless remote transmission mode.

[0009] The above-mentioned online monitoring device for high concentration of chloride ions in wastewater, the filter is a multi-stage filter, each stage of the filter has a built-in cylindrical or flat microfiltration membrane, nanofiltration membrane, ultrafiltration membrane or one or a combination thereof, and the filtration accuracy of the latter stage filter is higher than that of the previous stage filter.

[0010] In the above-mentioned online monitoring device for high concentration of chloride ions in wastewater, a water suction filter is installed at the end of the water inlet pipe of the water supply pump.

[0011] In the above-mentioned online monitoring device for high-concentration chloride ions in wastewater, an overflow pipe is installed on the overflow port on one side of the overflow tank.

[0012] In the above-mentioned on-line monitoring device for high-concentration chloride ions in wastewater, a drain pipe is installed on the side wall of the detection pool.

[0013] An online monitoring method for high concentration chloride ions in wastewater, the method comprising the following steps:

[0014] a. Start the water supply pump, and the wastewater to be tested will enter the overflow tank through the water supply pump, filter, and water inlet regulating valve in sequence;

[0015] b. Turn on the wastewater peristaltic pump and the reagent peristaltic pump. The special ionic strength buffer in the reagent bottle and the chlorine-containing wastewater in the overflow tank are quantitatively injected into the mixing tank according to a certain ratio by the reagent peristaltic pump and the wastewater peristaltic pump respectively. After being fully mixed in the mixing tank, they flow into the detection tank;

[0016] c. Start the chloride ion concentration detector, the composite electrode detects the wastewater in the detection pool, and transmits the measured electrode potential to the chloride ion concentration detector, which calculates the chloride ion concentration in the wastewater based on the linear relationship between the electrode potential and the logarithm of the chloride ion concentration, and displays the chloride ion concentration;

[0017] d. After the measurement is completed, open the mixing tank backwash valve and the backwash main valve, start the backwash pump, and the backwash pump draws deionized water from the backwash water tank to backwash the monitoring device.

[0018] In the above-mentioned online monitoring method for high concentration of chloride ions in wastewater, the chloride ion concentration detector calculates the chloride ion concentration in the wastewater based on the linear relationship between the electrode potential and the logarithm of the chloride ion concentration. The calculation formula used is as follows:

[0019]

[0020] b=m×I n +q

[0021]

[0022] Where E is the electrode potential, V; k is the electrode constant, V; γ is the activity coefficient of chloride ion; R is 8.314 J / mol / K; T is the absolute temperature, K; n is the correlation power exponent; F is the Faraday constant, 96485 C / mol; m is the correlation slope; I is the solution ionic strength; q is the correlation intercept; [Cl - ] is the chloride ion concentration, mol / L; [Cl - ]0 is the standard concentration of chloride ions, 1 mol / L; a is the temperature correction parameter; a′ is the temperature correction coefficient; b is the ionic strength correction term; nn is the number of ions in the solution; C i is the concentration of the i-th ion in the solution, mol / L; Z i is the charge of the i-th ion in the solution.

[0023] In the above-mentioned online monitoring method for high concentration of chloride ions in wastewater, the ionic strength buffer can be one or more combinations of sodium nitrate, potassium nitrate, sodium nitrite, potassium nitrite, sodium sulfate or potassium sulfate.

[0024] The present invention utilizes a filter to eliminate the interference of suspended matter in water on ion determination, and simultaneously adopts a solution dilution method to expand the detection range of chloride ion concentration, and expands the upper limit of accurate detection of chloride ions to 50000 mg / L; the method of correcting the activity coefficient of chloride ions by ionic strength greatly improves the detection accuracy of chloride ion concentration, and the measurement error can be stabilized at less than 5%, which can meet the requirements of rapid and accurate detection and monitoring of high-concentration chloride ions in wastewater, and ensure the safe and stable operation of industrial processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 It is a schematic diagram of the structure of the online monitoring device for high concentration chloride ions used in the present invention (the pipelines in the figure are represented by solid lines, and the guides or cables are represented by dot-dash lines).

[0027] The reference numerals in the accompanying drawings or text represent respectively: 1, DC power supply, 2, display switch, 3, chloride ion concentration detector, 4, composite electrode, 5, detection tank, 6, backwash pump, 7, water supply switch, 8, water supply pump, 9, water suction filter head, 10, backwash water tank, 11, primary filter, 12, secondary filter, 13, tertiary filter, 14, overflow tank, 15, overflow pipe, 16, wastewater peristaltic pump, 17, pharmaceutical peristaltic pump, 18, pharmaceutical bottle, 19, mixing tank, 20, backwash switch, 21, DCS distributed control system, 22, USB-485 serial port line, 23, computer, 24, drain pipe, 25, mixing tank backwash valve, 26, backwash main valve, 27, water inlet regulating valve. DETAILED DESCRIPTION

[0028] In order to solve the problem of accurate online monitoring of high-concentration chloride ions in industrial wastewater, the present invention improves on the basis of existing chloride ion detection instruments and provides an online monitoring device and method for high-concentration chloride ions in wastewater, which can not only eliminate the interference of suspended matter in water on ion determination, but also adopt a solution ion strength correction method to expand the upper limit of accurate detection of chloride ions to 50,000 mg / L, greatly improving the detection accuracy of chloride ion concentration, and can meet the requirements of rapid and accurate detection and monitoring of high-concentration chloride ions in wastewater, ensuring safe and stable operation of industrial processes.

[0029] See also Figure 1 The online monitoring device for high concentration of chloride ions in wastewater of the present invention comprises a DC power supply 1, a display switch 2, a chloride ion concentration detector 3, a composite electrode 4, a detection tank 5, a backwash pump 6, a water supply switch 7, a water supply pump 8, a water suction filter head 9, a backwash water tank 10, a filter (a primary filter 11, a secondary filter 12, a tertiary filter 13), an overflow tank 14, an overflow pipe 15, a wastewater peristaltic pump 16, a pharmaceutical peristaltic pump 17, a pharmaceutical bottle 18, a mixing tank 19, a backwash switch 20, a DCS distributed control system 21, a USB-485 serial port line 22, a computer 23, a drain pipe 24, a mixing tank backwash valve 25, a backwash main valve 26 and a water inlet regulating valve 27.

[0030] The DC power supply 1 includes a rechargeable battery pack and an AC / DC converter. The dual power supplies are automatically switched and are equipped with an over-voltage and under-voltage protector. During normal operation, the AC power supply supplies power to the entire device, and the battery pack is charged when the battery pack voltage is lower than 20V. In the event of a power outage, the battery pack provides temporary power supply to ensure the integrity of the signal control logic and protect the monitoring device.

[0031] The water supply switch 7, the water supply pump 8, the water suction filter head 9, the filter, the overflow tank 14, the overflow pipe 15 and the water inlet regulating valve 27 constitute a wastewater pretreatment device. The water suction filter head 9 is installed at the end of the water inlet pipe of the water supply pump 8, and the water outlet pipe is connected to the water inlet of the overflow tank 14 through the filter and the water inlet regulating valve 27 in turn, and the overflow pipe 15 is installed on the overflow port on one side of the overflow tank 14. The water supply pump 8 is used to obtain the chloride ion online monitoring water sample from the wastewater and inject it into the overflow tank 14; the water inlet regulating valve 27 is used to adjust the flow rate of the wastewater entering the overflow tank 14; the water suction filter head 9 is used to perform coarse filtration on the inhaled wastewater, and can filter larger silk fabrics and particulate matter such as hair. The filter is set with one or more stages of filters (three stages in the figure) according to the design requirements according to the direction of the water flow. The filter is built-in with one or a combination of cylindrical or flat microfiltration membranes, nanofiltration membranes, and ultrafiltration membranes. The filtering accuracy of the rear filter is higher than that of the previous filter.

[0032] The display switch 2, the chloride ion concentration detector 3, the composite electrode 4, the detection tank 5, the wastewater peristaltic pump 16, the reagent peristaltic pump 17, the reagent bottle 18, the mixing tank 19, the DCS distributed control system 21, the USB-485 serial port line 22, the computer 23, and the drain pipe 24 constitute the chloride ion detection device.

[0033] The water inlet end of the wastewater peristaltic pump 16 is connected to the overflow tank 14, and the water outlet end is connected to the mixing tank 19. The water inlet end of the reagent peristaltic pump 17 is connected to the reagent bottle 18, and the water outlet end is connected to the mixing tank 19. The detection tank 5 is connected to the mixing tank 19. The drain pipe 24 is installed on the side wall of the detection tank 5. The composite electrode 4 is installed inside the detection tank 5. The signal output end of the composite electrode 4 is connected to the chloride ion concentration detector 3, and the chloride ion concentration detector 3 is provided with a data transmission interface.

[0034] The backwash pump 6, the backwash water tank 10, the backwash switch 20, the mixing tank backwash valve 25, and the backwash main valve 26 constitute a backwash device. The water inlet pipe of the backwash pump 6 is connected to the backwash water tank 10, the water outlet pipe is connected to the water inlet end of the water inlet regulating valve 27 through the backwash main valve 26, the water inlet end of the mixing tank backwash valve 25 is connected to the water outlet end of the water inlet regulating valve 27, and the water outlet end is connected to the mixing tank 19.

[0035] During measurement, the water supply pump 8 is first started, and the wastewater to be tested enters the overflow tank 14 through the water suction filter head 9, the water supply pump 8, the filter, and the water inlet regulating valve 27 in sequence. When the wastewater in the overflow tank 14 reaches a certain height, the excess water sample is discharged to the waste liquid bottle or returned to the sampling port through the overflow pipe 15. Then the wastewater peristaltic pump 16 and the reagent peristaltic pump 17 are turned on, and the special ionic strength buffer in the reagent bottle 18 and the chlorine-containing wastewater in the overflow tank 14 are quantitatively injected into the mixing tank 19 by the reagent peristaltic pump 17 and the wastewater peristaltic pump 16 according to a certain ratio, and flow into the detection tank 5 after being fully mixed in the mixing tank 19, and detected by the composite electrode 4 in the detection tank 5; the electrode potential measured by the composite electrode 4 is transmitted to the chloride ion concentration detector 3, and the chloride ion concentration detector 3 calculates the chloride ion concentration in the wastewater according to the linear relationship between the electrode potential and the logarithm of the chloride ion concentration, and displays the chloride ion concentration. The special ionic strength buffer can be one or more combinations of sodium nitrate, potassium nitrate, sodium nitrite, potassium nitrite, sodium sulfate or potassium sulfate. The chloride ion concentration detector 3 is connected to the DCS distributed control system 21 and the computer 23 through a communication cable or a wireless remote transmission mode to upload data. After the measurement is completed, the liquid in the detection tank 5 is discharged to the waste liquid bottle or returned to the sampling port by the drain pipe 24. Then open the mixing tank backwash valve 25 and the backwash main valve 26, start the backwash pump 6, and the backwash pump 6 draws deionized water from the backwash water tank 10 to backwash the monitoring device.

[0036] In order to accurately obtain the concentration value of chloride ions in wastewater, the present invention sets a water absorption filter head 9 and a filter in the wastewater pretreatment device to reduce the interference of suspended matter in the wastewater on the measurement results, while protecting the composite electrode 4 and extending the service life of the composite electrode 4; secondly, considering the deviation of ion activity and ion concentration when the chloride ion concentration is high (the complexity of the relationship between the two is shown in formulas (2, 3, 4)), the activity coefficient correction method is used in data processing to correct the corresponding relationship between the electrode potential and the logarithm of the chloride ion concentration, thereby improving the detection accuracy and range. When the chloride ion concentration detector 3 calculates the chloride ion concentration in the wastewater based on the linear relationship between the electrode potential and the logarithm of the chloride ion concentration, the calculation formula used is as follows:

[0037]

[0038] b=m×I n +q (3)

[0039]

[0040] Where E is the electrode potential, V; k is the electrode constant, V; γ is the activity coefficient of chloride ion; R is 8.314 J / mol / K; T is the absolute temperature, K; n is the correlation power exponent; F is the Faraday constant, 96485 C / mol; m is the correlation slope; I is the solution ionic strength; q is the correlation intercept; [Cl- ] is the chloride ion concentration, mol / L; [Cl - ]0 is the standard concentration of chloride ions, 1 mol / L; a is the temperature correction parameter; a′ is the temperature correction coefficient; b is the ionic strength correction term; nn is the number of ions in the solution; C i is the concentration of the i-th ion in the solution, mol / L; Z i is the charge number of the i-th ion in the solution. γ is related to the ionic strength in the solution and is a constant value when the ionic strength of the solution is constant.

[0041] From formula (1), we can deduce:

[0042]

[0043] It can be seen that at this time, the electrode potential is approximately linearly related to the logarithm of the chloride ion concentration in the solution. After the wastewater to be tested is fully mixed with the special ionic strength buffer, the chloride ion determination is performed, so that the ionic strength of the solution in the detection pool fluctuates within a small range, and the activity coefficient γ of the chloride ion in the solution is approximately constant, thereby improving the detection accuracy.

[0044] At the same time, the detection range can be expanded by adjusting the mixing ratio of the wastewater to be tested and the special ionic strength buffer. For example, assuming that the chloride ion concentration of the wastewater to be tested is 3000mg / L, the corresponding potential is 57mV; when the mixing ratio of the special ionic strength buffer is 1:10, at the same 57mV potential, the chloride ion concentration range can be expanded to 30000mg / L, which is 10 times the original.

[0045]

[0046] Wherein, α is the mixing ratio of the wastewater to be tested and the ionic strength buffer.

[0047] Specific examples are given below to further describe the structure of the present invention.

[0048] Example 1

[0049] When the online monitoring device for high concentration chloride ions in wastewater is working, connect the power cord of the device, start the AC air switch of the DC power supply 1, and the DC power supply 1 works. Turn on the display switch 2 to start the chloride ion concentration detector 3, activate the chloride ion composite electrode 4 and put it into the detection tank 5; then turn on the water supply switch 7, the water supply pump 8 starts to work, and the water inlet pipe with the water suction filter head 9 starts to suck the wastewater solution from the sampling port. The wastewater enters the primary filter 11 for preliminary filtration, enters the secondary filter 12 for secondary filtration and the tertiary filter 13 for refiltration to reduce the interference of wastewater impurities on chloride ion detection, and finally the wastewater solution is led to the overflow tank 14. When the wastewater in the overflow tank 14 reaches a certain height, the excess water sample is discharged to the waste liquid bottle or returned to the sampling port through the overflow pipe 15. At this time, the wastewater peristaltic pump 16 and the reagent peristaltic pump 17 are turned on to extract the pre-treated wastewater and the special ionic strength buffer from the overflow tank 14 and the reagent bottle 18 in a certain ratio to the mixing tank 19 for full mixing and then enter the detection tank 5, and the chloride ion concentration detector 3 begins to display the chloride ion concentration in the wastewater; the detection data is transmitted to the host computer, i.e., the DCS distributed control system 21, through the output port of the chloride ion concentration detector 3, and the detection data is transmitted to the computer 23 through the USB-485 serial port line 22, and the synchronous display of the measurement data is realized on the computer 23. The measured wastewater liquid is discharged from the drain pipe 24 to the waste liquid bottle or returned to the sampling port. When the device is not used for a long time, the mixing tank backwash valve 25 and the backwash main valve 26 are opened, and the backwash pump 6 is started to draw deionized water from the backwash water tank 10 to backwash the monitoring device.

[0050] Example 2

[0051] When the online monitoring device for high concentration chloride ions in wastewater is working, the power cord of the device is connected, the AC air switch of the DC power supply 1 is started, and the DC power supply 1 is working. The display switch 2 is turned on to start the chloride ion concentration detector 3, and the chloride ion composite electrode 4 is activated and placed in the detection tank 5; secondly, the water supply switch 7 is turned on, the water supply pump 8 starts to work, and the water inlet pipe with the water suction filter head 9 starts to suck the wastewater solution from the sampling port, and the wastewater enters the primary filter 11 for preliminary filtration, and enters the secondary filter 12 for secondary filtration to reduce the interference of wastewater impurities on chloride ion detection, and finally the wastewater solution is led to the overflow tank 14. When the wastewater in the overflow tank 14 reaches a certain height, the excess water sample is discharged to the waste liquid bottle or returned to the sampling port through the overflow pipe 15. At this time, the wastewater peristaltic pump 16 and the reagent peristaltic pump 17 are turned on to extract the pre-treated wastewater and the special ionic strength buffer from the overflow tank 14 and the reagent bottle 18 in a certain ratio, and then the wastewater enters the detection tank 5 after being fully mixed in the mixing tank 19, and the chloride ion concentration detector 3 starts to display the chloride ion concentration in the wastewater; the detection data is transmitted to the host computer, i.e., the DCS distributed control system 21, through the output port of the chloride ion concentration detector 3, and the detection data is transmitted to the computer 23 through the USB-485 serial port line 22, and the synchronous display of the measurement data is realized on the computer 23. After the measurement, the liquid is discharged from the drain pipe 24 to the waste liquid bottle or returned to the sampling port. When it is not used for a long time, the mixing tank backwash valve 25 and the backwash main valve 26 are opened, and the backwash pump 6 is started to draw deionized water from the backwash water tank 10 to backwash the monitoring device.

[0052] Example 3

[0053] When the online monitoring device for high concentration chloride ions in wastewater is working, connect the power cord of the device, start the AC air switch of the DC power supply 1, and the DC power supply 1 works. Turn on the display switch 2 to start the chloride ion concentration detector 3, activate the chloride ion composite electrode 4 and put it into the detection tank 5; then turn on the pump switch 7, the water supply pump 8 starts to work, and the water inlet pipe with the water suction filter head 9 starts to suck the wastewater solution from the sampling port. The wastewater enters the primary filter 11 for preliminary filtration to reduce the interference of wastewater impurities on chloride ion detection, and finally the solution is led to the overflow tank 14. When the wastewater in the overflow tank 14 reaches a certain height, the excess water sample is discharged to the waste liquid bottle or returned to the sampling port through the overflow pipe 15. At this time, the wastewater peristaltic pump 16 and the reagent peristaltic pump 17 are turned on to extract the pre-treated wastewater and the special ionic strength buffer from the overflow tank 14 and the reagent bottle 18 in a certain ratio, and then the wastewater enters the detection tank 5 after being fully mixed in the mixing tank 19. The chloride ion concentration detector 3 starts to display the chloride ion concentration in the wastewater; the detection data is transmitted to the host computer, i.e., the DCS distributed control system 21, through the output port of the detector, and the detection data is transmitted to the computer 23 through the USB-485 serial port line 22, and the synchronous display of the measurement data is realized on the computer 23. After the measurement, the liquid is discharged from the drain pipe 24 to the waste liquid bottle or returned to the sampling port. When it is not used for a long time, the mixing tank backwash valve 25 and the backwash main valve 26 are opened, and the backwash pump 6 is started to draw deionized water from the backwash water tank 10 to backwash the monitoring device.

[0054] The present invention can realize the online accurate and rapid measurement of high concentration chloride ions in wastewater, opens up a new way to monitor high concentration chloride ions in solution, and solves the problem of large measurement error of high concentration chloride ions in wastewater by the original monitoring device. It effectively makes up for the shortcomings of the current online chloride ion monitoring device, is conducive to the rapid and accurate measurement and control of high concentration chloride ions in industrial processes such as wastewater treatment, ensures the safe and stable operation of industrial processes, and has broad application prospects.

Claims

1. An online monitoring device for high concentration chloride ions in wastewater, characterized in that: The invention comprises a water supply pump (8), a filter, a water inlet regulating valve (27), an overflow tank (14), a mixing tank (19), a detection tank (5), a wastewater peristaltic pump (16), a medicine peristaltic pump (17), a medicine bottle (18), a chloride ion concentration detector (3) and a composite electrode (4). The water inlet pipe of the water supply pump (8) is placed in the wastewater to be detected, the water outlet pipe is connected to the water inlet of the overflow tank (14) through the filter and the water inlet regulating valve (27) in sequence, the water inlet end of the wastewater peristaltic pump (16) is connected to the overflow tank (14), and the water outlet end is connected to the mixing tank (19), the water inlet end of the medicine peristaltic pump (17) is connected to the medicine bottle (18), and the water outlet end is connected to the mixing tank (19), the detection tank (5) is connected to the mixing tank (19), the composite electrode (4) is installed inside the detection tank (5), and the signal output end of the composite electrode (4) is connected to the chloride ion concentration detector (3).

2. The on-line monitoring device for high concentration of chloride ions in wastewater according to claim 1, characterized in that: It also includes a backwash pump (6), a backwash water tank (10), a mixing tank backwash valve (25) and a backwash main valve (26); the water inlet pipe of the backwash pump (6) is connected to the backwash water tank (10); the water outlet pipe is connected to the water inlet end of the water inlet regulating valve (27) through the backwash main valve (26); the water inlet end of the mixing tank backwash valve (25) is connected to the water outlet end of the water inlet regulating valve (27); and the water outlet end is connected to the mixing tank (19).

3. The on-line monitoring device for high concentration of chloride ions in wastewater according to claim 1, characterized in that: It also comprises a DCS distributed control system (21) and a computer (23), wherein the DCS distributed control system (21) and the computer (23) are connected to the chloride ion concentration detector (3) via a communication cable or a wireless remote transmission mode.

4. The on-line monitoring device for high concentration of chloride ions in wastewater according to claim 1, characterized in that: The filter is a multi-stage filter, each stage of the filter is built with one or a combination of cylindrical or flat microfiltration membrane, nanofiltration membrane, and ultrafiltration membrane, and the filtering accuracy of the latter stage filter is higher than that of the previous stage filter.

5. The on-line monitoring device for high concentration of chloride ions in wastewater according to claim 1, characterized in that: A water suction filter (9) is installed at the end of the water inlet pipe of the water supply pump (8).

6. The on-line monitoring device for high concentration of chloride ions in wastewater according to claim 1, characterized in that: An overflow pipe (15) is installed on the overflow port on one side of the overflow pool (14).

7. The on-line monitoring device for high concentration of chloride ions in wastewater according to claim 1, characterized in that: A drainage pipe (24) is installed on the side wall of the detection pool (5).

8. An on-line monitoring method for high concentration of chloride ions in wastewater using the monitoring device of any one of claims 2 to 7, the method comprising the following steps: a. Start the water supply pump (8), and the wastewater to be tested passes through the water supply pump (8), the filter, and the water inlet regulating valve (27) into the overflow tank (14); b. Turn on the wastewater peristaltic pump (16) and the reagent peristaltic pump (17), and the special ionic strength buffer in the reagent bottle (18) and the chlorine-containing wastewater in the overflow tank (14) are respectively injected into the mixing tank (19) in a certain ratio by the reagent peristaltic pump (17) and the wastewater peristaltic pump (16), and then flow into the detection tank (5) after being fully mixed in the mixing tank (19); c. Start the chloride ion concentration detector (3), the composite electrode (4) detects the wastewater in the detection tank (5), and transmits the measured electrode potential to the chloride ion concentration detector (3), and the chloride ion concentration detector (3) calculates the chloride ion concentration in the wastewater based on the linear relationship between the electrode potential and the logarithm of the chloride ion concentration, and displays the chloride ion concentration; d. After the measurement is completed, the mixing tank backwash valve (25) and the backwash main valve (26) are opened, and the backwash pump (6) is started. The backwash pump (6) draws deionized water from the backwash water tank (10) to backwash the monitoring device.

9. According to the online monitoring method for high concentration of chloride ions in wastewater as claimed in claim 8, the chloride ion concentration detector (3) calculates the chloride ion concentration in the wastewater according to the linear relationship between the electrode potential and the logarithm of the chloride ion concentration, and the calculation formula used is as follows: b=m×I n +q (3) in, E is the electrode potential, V; k is the electrode constant, V; α is the dilution factor of the chloride ion concentration; γ is the activity coefficient of the chloride ion; R is 8.314 J / mol / K; T is the absolute temperature, K; n is the correlation power exponent; F is the Faraday constant, 96485 C / mol; m is the correlation slope; I is the solution ionic strength; q is the correlation intercept; [Cl - ] is the chloride ion concentration, mol / L; [Cl - ]0 is the standard concentration of chloride ions, 1 mol / L; a is the temperature correction parameter; a′ is the temperature correction coefficient, and b is the ionic strength correction term.

10. The online monitoring method for high concentration chloride ions in wastewater according to claim 8, wherein the ionic strength buffer can be one or more combinations of sodium nitrate, potassium nitrate, sodium nitrite, potassium nitrite, sodium sulfate or potassium sulfate.

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