Urban reclaimed water lime softening treatment water quality on-line monitoring device and use method

Abstract

The invention relates to the technical field of water quality on-line monitoring, and discloses an urban reclaimed water lime softening treatment water quality on-line monitoring device and a use method, the monitoring device comprises a sampling unit, a pretreatment unit, a cleaning unit, a detection unit and a control center unit; one side of the sampling unit is connected with a water inlet sampling pipe and a water outlet sampling pipe of the clarification tank, and the other side of the sampling unit is connected with the pretreatment unit through a pipeline; the pretreatment unit is used for clarifying urban reclaimed water or circulating water, and the pretreatment unit is connected with the cleaning unit through a pipeline; the detection unit comprises a phenolphthalein alkalinity meter, a total alkalinity meter, a hardness meter, a conductivity meter and a pH meter, and the detection unit is connected with the pretreatment unit and a factory discharge pipe; the control central unit is electrically connected with the sampling unit, the pretreatment unit, the cleaning unit, the phenolphthalein alkalinity meter, the total alkalinity meter, the hardness meter, the conductivity meter and the pH meter respectively. According to the invention, a plurality of water quality indexes are automatically monitored on line, and the problems of particle pollution blockage and inaccurate detection in a water sample are solved at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water quality online monitoring, in particular to a device for online monitoring of water quality in lime softening treatment of urban reclaimed water and a use method thereof. BACKGROUND

[0002] To protect the increasingly scarce water resources, urban reclaimed water has become a normal water source for power plants. Since urban reclaimed water usually has the characteristics of colloid, organic matter, total phosphorus, alkalinity and hardness, it needs to be further treated to meet the production process water of power plants. The lime softening treatment process of urban reclaimed water can remove components such as free carbon dioxide CO2, calcium bicarbonate Ca(HCO3)2 and magnesium bicarbonate Mg(HCO3)2, and the softening reaction is: CO2+Ca(OH)2→CaCO3↓+H2O (1) Ca(HCO3)2+Ca(OH)2→2CaCO3↓+2H2O (2) Mg(HCO3)2+2Ca(OH)2→2CaCO3↓+Mg(OH)2↓+2H2O (3) The lime softening coagulation treatment process of urban reclaimed water has the treatment effect of removing temporary hardness, and can effectively remove colloids, organic matter, total phosphorus and other substances in water after coagulation and clarification. It is commonly used as a treatment process for urban reclaimed water and recycled water in power plants.

[0003] The operation control of lime softening coagulation treatment should be adjusted according to the changes of water alkalinity, hardness, water quality and flow, etc. The dosing of lime and sludge discharge operation should be adjusted, and the reaction process should be monitored and controlled in time. Since the traditional lime softening coagulation treatment cannot measure the alkalinity (HCO3-, CO3 2 ) and hardness of the inlet and outlet water online, only the pH online monitoring value can be used to approximate the adjustment of the lime slurry dosage, and the sludge is discharged at regular intervals. The alkalinity and hardness are monitored by manual test to monitor the softening effect. This leads to the problems of large and lagging lime dosing deviation in traditional lime softening coagulation treatment, high turbidity of effluent caused by improper sludge control, lagging feedback of softening results, and poor adjustment, which causes unstable treatment effluent, seriously threatens the safe operation of downstream water equipment, high labor intensity, and cannot realize intelligent operation. SUMMARY

[0004] In order to solve the existing problems, the present application aims to provide a kind of city reclaimed water lime softening treatment water quality on-line monitoring device and use method, realize a set of instrument automatic on-line monitoring city reclaimed water lime softening treatment inlet water and outlet water alkalinity, hardness, pH value, turbidity and conductivity, while solve the problem of suspended particle pollution in the water sample being measured and influence detection result, can provide adjustment information for city reclaimed water lime softening treatment running in lime addition and sludge discharge etc., timely monitoring treatment effect, greatly improve city reclaimed water lime softening treatment effect and stability, reduce labor intensity, lay the foundation for realizing city reclaimed water lime softening treatment intelligent operation.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme.

[0006] The present application provides a kind of city reclaimed water lime softening treatment water quality on-line monitoring device and use method, including sampling unit, pre-treatment unit, cleaning unit, detection unit and control center unit;The side of the sampling unit is connected with the inlet water sampling pipe and outlet water sampling pipe of clarifier, and the other side is connected with the pipeline of pre-treatment unit;The pre-treatment unit is used to clarify city reclaimed water or circulating water, and the pipeline of pre-treatment unit and cleaning unit is connected;The detection unit includes phenolphthalein alkalinity table, total alkalinity table, hardness table, conductivity table and pH meter, and the detection unit is connected with pre-treatment unit and plant discharge pipe respectively;The control center unit is electrically connected with sampling unit, pre-treatment unit, cleaning unit, phenolphthalein alkalinity table, total alkalinity table, hardness table, conductivity table and pH meter respectively.

[0007] As a further improvement of the present application, the sampling unit includes inlet water sampling valve, outlet water sampling valve, sampling pump, pump inlet main pipe and pump outlet main pipe;The inlet water sampling valve inlet is connected with the inlet water sampling pipe of clarifier, and the inlet water sampling valve outlet is connected with the pump inlet main pipe;The outlet water sampling valve inlet is connected with the outlet water sampling pipe of clarifier, and the outlet water sampling valve outlet is connected with the pump inlet main pipe;The sampling pump inlet is connected with the inlet main pipe, and the sampling pump outlet is connected with the pump outlet main pipe.

[0008] As a further improvement of the present application, the pre-treatment unit includes filter, flushing discharge valve and blowdown valve;The filter inlet is connected with the pump outlet main pipe, and the filter outlet is connected with the filter outlet main pipe;The flushing discharge valve inlet is connected with the end of filter outlet main pipe, and the flushing discharge valve outlet is connected with the discharge pipe;The blowdown valve inlet is connected with the filter bottom outlet, and the blowdown valve outlet is connected with the discharge pipe.

[0009] As a further improvement of the present application, the cleaning unit includes cleaning pump and cleaning agent storage tank;The cleaning pump inlet is connected with the cleaning agent storage tank, and the cleaning pump outlet is connected with the pump outlet main pipe;The cleaning agent outlet is connected with the cleaning pump inlet.

[0010] As a further improvement of the present application, the phenolphthalein alkalinity meter inlet is connected with the filtering outlet manifold, and the phenolphthalein alkalinity meter outlet is connected with the discharge pipe; the total alkalinity meter inlet is connected with the filtering outlet manifold, and the total alkalinity meter outlet is connected with the discharge pipe; the hardness meter inlet is connected with the filtering outlet manifold, and the hardness meter outlet is connected with the discharge pipe; the conductivity meter inlet is connected with the filtering outlet manifold, and the conductivity meter outlet is connected with the pH meter inlet; the pH meter inlet is connected with the conductivity meter outlet, and the pH meter outlet is connected with the discharge pipe.

[0011] As a further improvement of the present application, the detection unit further comprises a flow splitting device; the top of the flow splitting device is connected with the filtering outlet manifold, and the side wall of the flow splitting device is provided with openings and connected with the phenolphthalein alkalinity meter, the total alkalinity meter, the hardness meter and the conductivity meter, respectively.

[0012] As a further improvement of the present application, the control center unit body is a PLC controller, which is electrically connected with the water inlet sampling valve, the water outlet sampling valve, the sampling pump, the cleaning pump and the flushing discharge valve, respectively.

[0013] As a further improvement of the present application, the material of the storage tank is one of 304 / 316 stainless steel, glass fiber reinforced plastic, glazed ceramic and polytetrafluoroethylene.

[0014] The present application also discloses a use method of the water quality online monitoring device for urban reclaimed water lime softening treatment, which comprises the following steps: starting the sampling unit according to the detection water sample requirement; starting the pretreatment unit; controlling the phenolphthalein alkalinity meter, the total alkalinity meter, the hardness meter, the conductivity meter and the pH meter through the control center unit, and uploading the detection result; performing the next cycle at intervals; starting the cleaning unit when the cycle is performed for a preset number of times; and closing the sampling unit, the pretreatment unit, the cleaning unit and the detection unit.

[0015] As a further improvement of the present application, the starting of the sampling unit comprises the following steps: when the water sample of the clarifier inlet is detected, the PLC controller opens the clarifier inlet sampling valve and closes the outlet sampling valve; and when the water sample of the clarifier outlet is detected, the PLC controller opens the clarifier outlet sampling valve and closes the inlet sampling valve.

[0016] The present application has the following beneficial effects: The present application proposes a complete water quality online monitoring device architecture, which realizes comprehensive and real-time monitoring of the water quality in the urban reclaimed water lime softening treatment process through the cooperative work of the units, and provides reliable data support for the stable operation and optimization of the water treatment system.

[0017] Preferably, through the influent sampling valve, effluent sampling valve, sampling pump, the water sample can be accurately and conveniently collected from the influent and effluent of the clarifier, providing accurate and stable samples for subsequent water quality detection, ensuring the reliability of the detection results.

[0018] Preferably, the pretreatment unit can preliminarily process the collected water sample to remove impurities and particulate matter in the water sample, improving the accuracy of water quality detection; at the same time, the setting of the flushing discharge valve and the blowdown valve facilitates the cleaning and maintenance of the filter, ensuring the normal operation of the pretreatment unit.

[0019] Preferably, the cleaning unit can periodically clean the entire monitoring device to prevent impurities and pollutants in the water sample from accumulating in the device, affecting the detection accuracy and the service life of the device, and ensuring long-term stable operation of the device.

[0020] Preferably, each detection instrument is connected in parallel with the filter outlet main pipe, so that the water sample can pass through each detection instrument in turn to realize accurate detection of multiple indicators of water quality, and the detected water sample is discharged to a designated location to ensure smooth detection process.

[0021] Preferably, the shunt device synchronously connects the water outlet of the filter outlet main pipe to the instruments of the detection unit, and ensures that the shunted water to be detected has uniform water quality composition through the stirring blades, reducing uneven shunting of filtered water or vertical stratification due to uneven water quality composition, which leads to detection distortion of the water to be detected entering the detection unit.

[0022] Preferably, the PLC controller as the control center can realize automatic control of the entire monitoring device, accurately control the operation of each component according to the preset program, improve the operation convenience and running stability of the device, and reduce manual intervention.

[0023] Preferably, the material of the storage tank requires acid and alkali resistance and can adapt to the chemical properties of the cleaning agent to ensure the service life and the quality of the cleaning agent. 304 / 316 stainless steel, glass fiber reinforced plastic, glazed ceramic or polytetrafluoroethylene all meet the material requirements of the storage tank.

[0024] The patent also discloses a use method of the urban reclaimed water lime softening treatment water quality online monitoring device, which enables the operator to operate the device according to the standard process, ensures the normal operation of the device, realizes continuous and stable monitoring of water quality, and discovers water quality changes in time.

[0025] Preferably, the operation steps of the sampling unit are refined, enabling the operator to accurately and conveniently collect the required water sample, improving the accuracy and efficiency of sampling, and avoiding detection result deviation caused by sampling errors. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings: Figure 1 Structure diagram of the water quality on-line monitoring device for the lime softening treatment of reclaimed water in a city according to Embodiment 1; Figure 2 Step diagram of the use method of the water quality on-line monitoring device for the lime softening treatment of reclaimed water in a city according to Embodiment 1; Figure 3 Structure diagram of the water quality on-line monitoring device for the lime softening treatment of reclaimed water in a city according to Embodiment 3; Figure 4 Structure diagram of the shunt device of the water quality on-line monitoring device for the lime softening treatment of reclaimed water in a city according to Embodiment 3; In the drawings, 1 is an inlet water sampling valve, 2 is an outlet water sampling valve, 3 is a sampling pump, 4 is a cleaning pump, 5 is a cleaning agent storage tank, 6 is a PLC controller, 7 is a filter, 8 is a flushing discharge valve, 9 is a phenolphthalein alkalinity meter, 10 is a total alkalinity meter, 11 is a hardness meter, 12 is a conductivity meter, 13 is a pH meter, 14 is a pump inlet main pipe, 15 is a pump outlet main pipe, 16 is a filter outlet main pipe, 17 is a discharge pipe, 18 is a blowdown valve, 19 is a shunt device, and 20 is a stirring blade. DETAILED DESCRIPTION

[0027] In order to make the technical solution in the application better understood by the people in the technical field, the technical solution in the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all the other embodiments obtained by the people in the technical field without creative labor should belong to the scope of protection of the application.

[0028] It should be noted that when an element is referred to as being “provided on” another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being “connected” to another element, it can be directly connected to the other element or there can be an intervening element. The terms “vertical”, “horizontal”, “left”, “right”, and similar expressions used herein are only for the purpose of illustration and do not represent the only embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] Example 1 like Figure 1 As shown, this embodiment provides an online monitoring device for urban greywater softening treatment, including a sampling unit, a pretreatment unit, a cleaning unit, a detection unit, and a control center unit. One side of the sampling unit is connected to the inlet and outlet sampling pipes of the clarification tank, and the other side is connected to the pretreatment unit pipeline. The pretreatment unit is used to clarify urban greywater or circulating water, and the pretreatment unit and the cleaning unit pipeline are connected. The detection unit includes a phenolphthalein alkalinity meter 9, a total alkalinity meter 10, a hardness meter 11, a conductivity meter 12, and a pH meter 13. The detection unit is connected to the pretreatment unit and the plant discharge pipe 17, respectively. The control center unit is electrically connected to the sampling unit, the pretreatment unit, the cleaning unit, the phenolphthalein alkalinity meter 9, the total alkalinity meter 10, the hardness meter 11, the conductivity meter 12, and the pH meter 13, respectively.

[0031] Specifically, the sampling unit includes an inlet sampling valve 1, an outlet sampling valve 2, a sampling pump 3, a pump inlet header 14, and a pump outlet header 15; the inlet of the inlet sampling valve 1 is connected to the inlet sampling pipe of the clarifier, and the outlet of the inlet sampling valve 1 is connected to the pump inlet header 14; the inlet of the outlet sampling valve 2 is connected to the outlet sampling pipe of the clarifier, and the outlet of the outlet sampling valve 2 is connected to the pump inlet header 14; the inlet of the sampling pump 3 is connected to the inlet header, and the outlet of the sampling pump 3 is connected to the pump outlet header 15.

[0032] Specifically, the pretreatment unit includes a filter 7, a flushing discharge valve 8, and a drain valve 18; the inlet of the filter 7 is connected to the pump outlet header 15, and the outlet of the filter 7 is connected to the filter outlet header; the inlet of the flushing discharge valve 8 is connected to the end of the filter outlet header, and the outlet of the flushing discharge valve 8 is connected to the discharge pipe 17; the inlet of the drain valve 18 is connected to the bottom outlet of the filter 7, and the outlet of the drain valve 18 is connected to the discharge pipe 17.

[0033] Specifically, the cleaning unit includes a cleaning pump 4 and a cleaning agent storage tank 5; the inlet of the cleaning pump 4 is connected to the cleaning agent storage tank 5, and the outlet of the cleaning pump 4 is connected to the pump outlet header 15; the cleaning agent outlet is connected to the inlet of the cleaning pump 4.

[0034] The phenolphthalein alkalinity table 9 inlet is connected with the filtering outlet mother pipe 16, the phenolphthalein alkalinity table 9 outlet is connected with the discharge pipe 17; the total alkalinity table 10 inlet is connected with the filtering outlet mother pipe 16, the total alkalinity table 10 outlet is connected with the discharge pipe 17; the hardness table 11 inlet is connected with the filtering outlet mother pipe 16, the hardness table 11 outlet is connected with the discharge pipe 17; the conductivity table 12 inlet is connected with the filtering outlet mother pipe 16, the conductivity table 12 outlet is connected with the pH meter 13 inlet; the pH meter 13 inlet is connected with the conductivity table 12 outlet, and the pH meter 13 outlet is connected with the discharge pipe 17.

[0035] The control center unit body is a PLC controller 6, and the PLC controller 6 is electrically connected with the water inlet sampling valve 1, the water outlet sampling valve 2, the sampling pump 3, the cleaning pump 4 and the flushing discharge valve 8 respectively.

[0036] Specifically, the material of the storage tank is 304 stainless steel material. The 304 stainless steel has good resistance to organic acid, weak base and dilute sulfuric acid and dilute nitric acid at room temperature.

[0037] The application further discloses a use method of the urban reclaimed water lime softening treatment water quality online monitoring device, which comprises the following steps: starting the sampling unit according to the detection water sample requirement; starting the pretreatment unit; controlling the phenolphthalein alkalinity table 9, the total alkalinity table 10, the hardness table 11, the conductivity table 12 and the pH meter 13 through the control center unit, and uploading the detection result; performing the next cycle at intervals; starting the cleaning unit when the cycle is performed for a preset number of times; and closing the sampling unit, the pretreatment unit, the cleaning unit and the detection unit.

[0038] The starting of the sampling unit comprises the following steps: when the water sample of the clarifier inlet is detected, the PLC controller 6 opens the clarifier water inlet sampling valve 1 and closes the water outlet sampling valve 2; and when the water sample of the clarifier outlet is detected, the PLC controller 6 opens the clarifier water outlet sampling valve 2 and closes the water inlet sampling valve 1.

[0039] When the water inlet detection or the water outlet detection is alternately performed, the preset number of times is 20; and when the water inlet detection is performed for 15 times continuously and then the water outlet detection is performed, the preset number of times is 15.

[0040] The above method reasonably sets the starting time of the cleaning unit, ensures the cleanliness of the device in the running process, avoids the influence of impurity accumulation on the detection result, avoids the resource waste caused by excessive cleaning, improves the use efficiency and economic benefit of the device.

[0041] Figure 2 The use method of the urban reclaimed water lime softening treatment water quality online monitoring device is displayed.

[0042] Specifically, the use method of the water quality on-line monitoring device for lime softening treatment of urban reclaimed water in the embodiment includes the following steps: S1: According to the detection water sample requirements, select to open the clarifier inlet water sampling valve 1 or outlet water sampling valve 2; S2: Open the blowdown valve 18, start the sampling pump 3, and flush for 2 minutes; S3: Open the flushing discharge valve 8, close the blowdown valve 18, and flush for 2 minutes; S4: The PLC controller 65 controls the phenolphthalein alkalinity meter 9, total alkalinity meter 10, hardness meter 11, conductivity meter 12, and pH meter 13 to start and stop detection, and reads the detection results of each instrument; S5: According to whether the clarifier inlet water sampling valve 1 or outlet water sampling valve 2 is opened, upload the detection results; S6: Open the blowdown valve 18, close the flushing discharge valve 8, and flush for 2 minutes; S7: Close the sampling pump 3, blowdown valve 18, inlet water sampling valve 1, and outlet water sampling valve 2.

[0043] The use method realizes automatic on-line monitoring of alkalinity, hardness, pH value, turbidity, and conductivity of inlet water and outlet water of a set of instruments for lime softening treatment of urban reclaimed water, solves the problems of pipeline blockage and influence on detection results caused by suspended particles in the measured water sample, and reduces equipment cost.

[0044] Embodiment 2 The water quality on-line monitoring device for lime softening treatment of urban reclaimed water in the embodiment is used for treating urban reclaimed water lime softening coagulation mechanical stirring clarifier.

[0045] Core problem 1: The water quality and water inflow of urban reclaimed water lime softening coagulation treatment fluctuate greatly and frequently, from about 300 m 3 / h to full load 1300 m 3 / h, and then from 1300 m 3 / h to about 300 m 3 / h, the temporary hardness of the inlet water changes within 100-300 mg / L within one day, which causes lime and other reagents to be unable to be timely adjusted, the pH and turbidity of the outlet water of the mechanical stirring clarifier fluctuate greatly (the pH fluctuation reaches 9.2-11.0, and the turbidity exceeds 10 NTU), the treatment effect is unstable, and the safe and stable operation of the downstream water treatment equipment is seriously affected.

[0046] S1: Pipeline connection: connect the inlet water sampling valve 1 of the device with the inlet water sampling pipe of the mechanical stirring clarifier, and connect the outlet water sampling valve 2 with the outlet water sampling pipe of the mechanical stirring clarifier.

[0047] S2: Determine the detection water sample: according to the detection water sample requirements, select to open the clarifier inlet water sampling valve 1 or outlet water sampling valve 2; S3: sample line flushing: open blowdown valve 18, start sample pump 3, flush for 2 minutes; S4: detection line flushing: open flushing drain valve 8, close blowdown valve 18, flush for 2 minutes; S5: detection: PLC controller 65 controls phenolphthalein alkalinity meter 9, total alkalinity meter 10, hardness meter 11, conductivity meter 12 and pH meter 13 to start and stop detection, and reads the detection results of each meter; S6: data uploading: upload the detection results according to whether the clear well inlet water sampling valve 1 or outlet water sampling valve 2 is opened; S7: filter 7 flushing: open blowdown valve 18, close flushing drain valve 8, flush for 2 minutes; S8: end: close sample pump 3, blowdown valve 18, inlet water sampling valve 1 and outlet water sampling valve 2.

[0048] The device is suitable for online monitoring of water quality in urban water lime softening and coagulation treatment, realizes automatic online monitoring of water quality alkalinity, hardness, pH value, turbidity and conductivity by a set of meters, solves the problems of pipeline blockage and influence on detection results caused by suspended particles in the measured water sample, provides basis for timely adjustment of lime dosage and sludge discharge in urban water lime softening treatment, timely monitoring of treatment effect, greatly improves the effect and stability of urban water lime softening treatment, reduces labor intensity, and provides a solid foundation for intelligent operation of urban water lime softening treatment.

[0049] The storage tank in the embodiment is made of glass fiber reinforced plastic material. This material can use unsaturated polyester resin as matrix and glass fiber as reinforcing material, and can optimize corrosion resistance by selecting different resin types, such as vinyl ester resin FRP, which can resist concentrated sulfuric acid and 30% or less sodium hydroxide solution, and has a wide pH application range.

[0050] Example 3 The difference from the embodiment is that: 1) It further comprises a flow splitting device 19.

[0051] As shown in Figure 3 , the top of the flow splitting device 19 is connected to the filter outlet mother pipe 16, and the side wall of the flow splitting device 19 is provided with openings and is connected to the phenolphthalein alkalinity meter 9, total alkalinity meter 10, hardness meter 11 and conductivity meter 12, respectively. As shown in Figure 4 , stirring blades 20 are arranged in the flow splitting device 19, and four holes are arranged on the inner wall of the flow splitting device 19 at the height of the stirring blades 20, which are used to connect the phenolphthalein alkalinity meter 9, total alkalinity meter 10, hardness meter 11 and conductivity meter 12. Since phosphates, phosphates and magnesium ions in urban water may be dissolved in water, even after passing through the filter device, they are still easy to precipitate due to factors such as flow rate and temperature, which makes it necessary to add the stirring blades 20.

[0052] The arrangement of the shunt device 19 synchronously leads the filtered water outlet of the outlet pipe 16 to the instrument of the detection unit, and the stirring blade 20 ensures that the shunted water to be detected has a uniform water quality composition, reduces the uneven shunting of the filtered water or the vertical stratification caused by the uneven concentration of water quality components, and causes the detection distortion of the water to be detected entering the detection unit.

[0053] The storage tank in the embodiment is made of polytetrafluoroethylene. The polytetrafluoroethylene can withstand strong acid and strong base, and has a wide applicable temperature range.

[0054] The above embodiment is only one of the implementation manners of the technical scheme of the present application, and the scope of the present application is not limited to the above embodiment, but also includes any changes, substitutions and other implementation manners easily thought by those skilled in the art within the technical scope disclosed by the present application.

Claims

1. An on-line monitoring device for water quality in a municipal water stone lime softening process, characterized by, It includes sampling unit, pretreatment unit, cleaning unit, detection unit and control center unit; one side of the sampling unit is connected with the inlet and outlet sampling pipes of the clarifier, and the other side is connected with the pipeline of the pretreatment unit; the pretreatment unit is used for clarifying the municipal reclaimed water or circulating water, and the pipeline of the pretreatment unit is connected with the cleaning unit; the detection unit includes phenolphthalein alkalinity table (9), total alkalinity table (10), hardness table (11), conductivity table (12) and pH meter (13), and the detection unit is respectively connected with the pretreatment unit and the plant discharge pipe; the control center unit is respectively connected with the sampling unit, the pretreatment unit, the cleaning unit, the phenolphthalein alkalinity table (9), the total alkalinity table (10), the hardness table (11), the conductivity table (12) and the pH meter (13).

2. The device according to claim 1, wherein the device is characterized in that, The sampling unit includes inlet sampling valve (1), outlet sampling valve (2), sampling pump (3), pump inlet main pipe (14) and pump outlet main pipe (15); The inlet of the inlet sampling valve (1) is connected with the inlet sampling pipe of the clarifier, and the outlet of the inlet sampling valve (1) is connected with the pump inlet main pipe (14); The inlet of the outlet sampling valve (2) is connected with the outlet sampling pipe of the clarifier, and the outlet of the outlet sampling valve (2) is connected with the pump inlet main pipe (14); The inlet of the sampling pump (3) is connected with the inlet main pipe (14), and the outlet of the sampling pump (3) is connected with the pump outlet main pipe (15).

3. The device according to claim 2, wherein the device is characterized in that, The pretreatment unit includes filter (7), flushing discharge valve (8), filter outlet main pipe (16), discharge pipe (17) and blowdown valve (18); The inlet of the filter (7) is connected with the pump outlet main pipe (15), and the outlet of the filter (7) is connected with the filter outlet main pipe (16); The inlet of the flushing discharge valve (8) is connected with the end of the filter outlet main pipe (16), and the outlet of the flushing discharge valve (8) is connected with the discharge pipe (17); The inlet of the blowdown valve (18) is connected with the bottom outlet of the filter (7), and the outlet of the blowdown valve (18) is connected with the discharge pipe (17).

4. The device according to claim 1, wherein the device is characterized in that, The cleaning unit includes cleaning pump (4) and cleaning agent storage tank (5); The inlet of the cleaning pump (4) is connected with the cleaning agent storage tank (5), and the outlet of the cleaning pump (4) is connected with the pump outlet main pipe (15).

5. The device according to claim 3, wherein the device is characterized in that, The inlet of the phenolphthalein alkalinity table (9) is connected with the filter outlet main pipe (16), and the outlet of the phenolphthalein alkalinity table (9) is connected with the discharge pipe (17); The inlet of the total alkalinity table (10) is connected with the filter outlet main pipe (16), and the outlet of the total alkalinity table (10) is connected with the discharge pipe (17); The inlet of the hardness table (11) is connected with the filter outlet main pipe (16), and the outlet of the hardness table (11) is connected with the discharge pipe (17); The inlet of the conductivity table (12) is connected with the filter outlet main pipe (16), and the outlet of the conductivity table (12) is connected with the inlet of the pH meter (13); The inlet of the pH meter (13) is connected with the outlet of the conductivity table (12), and the outlet of the pH meter (13) is connected with the discharge pipe (17).

6. The device according to claim 3, wherein the device is characterized in that, The detection unit further comprises a shunt device (19); the top of the shunt device (19) is connected with the filter outlet mother pipe (16), and the side wall of the shunt device (19) is perforated and connected with the phenolphthalein alkalinity table (9), the total alkalinity table (10), the hardness table (11) and the conductivity table (12) respectively.

7. The device according to claim 3, wherein the device is characterized in that, The control center unit body is a PLC controller (6), and the PLC controller (6) is electrically connected with the water inlet sampling valve (1), the water outlet sampling valve (2), the sampling pump (3), the cleaning pump (4) and the flushing discharge valve (8) respectively.

8. The device according to claim 4, wherein the device is characterized in that, The material of the storage tank (5) is one of 304 / 316 stainless steel, glass fiber reinforced plastic, glazed ceramic and polytetrafluoroethylene.

9. The use method of the water quality on-line monitoring device for lime softening treatment of urban reclaimed water according to any one of claims 1-8, characterized in that, According to the detection water sample requirements, the sampling unit is started; The pretreatment unit is started; The phenolphthalein alkalinity table (9), the total alkalinity table (10), the hardness table (11), the conductivity table (12) and the pH meter (13) are controlled by the control center unit, and the detection results are uploaded; The next cycle is carried out at intervals; when the above cycle is carried out for a preset number of times, the cleaning unit is started; The sampling unit, the pretreatment unit, the cleaning unit and the detection unit are closed.

10. The use of the device for on-line monitoring of water quality in the process of lime softening of municipal water as claimed in claim 9, characterized in that, The starting of the sampling unit comprises the following steps: When the water sample of the clarifier inlet is detected, the PLC controller (6) opens the clarifier inlet sampling valve (1) and closes the water outlet sampling valve (2); when the water sample of the clarifier outlet is detected, the PLC controller (6) opens the clarifier outlet sampling valve (2) and closes the water inlet sampling valve (1).

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