Nuclear power plant non-radioactive wastewater treatment system

Abstract

This invention provides a non-radioactive wastewater treatment system for nuclear power plants, comprising an inlet pipeline, a selective wastewater collection unit, a wastewater treatment unit, and a drainage pipeline. The selective wastewater collection unit includes a first wastewater collection tank, a second wastewater collection tank, and a third wastewater collection tank. The wastewater treatment unit includes a reaction tank unit and a dosing unit. The reaction tank unit includes a pH adjustment tank, a primary chemical reaction tank, a secondary chemical reaction tank, a sedimentation and clarification tank, and a final discharge tank connected in sequence. The dosing unit includes an acid dosing unit, an alkali dosing unit, an oxidation dosing unit, a phosphorus removal dosing unit, a coagulant aid dosing unit, and a reduction dosing unit. The acid dosing unit and the alkali dosing unit are respectively connected to the pH adjustment tank and the final discharge tank. The oxidation dosing unit and the phosphorus removal dosing unit are both connected to the primary chemical reaction tank. The coagulant aid dosing unit is connected to the secondary chemical reaction tank. The reduction dosing unit is connected between the final discharge tank and the drainage pipeline.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant wastewater treatment technology, and in particular to a non-radioactive wastewater treatment system for nuclear power plants. Background Technology

[0002] Nuclear power plants generate non-radioactive production wastewater (hereinafter referred to as non-radioactive wastewater) during normal operation. In recent years, with the country's increasing emphasis on environmental protection and the environmental requirements of local environmental protection departments, nuclear power plants need to treat non-radioactive wastewater to meet discharge standards or for resource recycling.

[0003] Non-radiative wastewater from nuclear power plants mainly includes non-radiative wastewater during normal operation and non-radiative wastewater during commissioning. The water quality of non-radiative wastewater during operation is as follows: pH 8.5-9.2, Chemical Oxygen Demand (CODCr) ≤ 15 mg / L, Total Nitrogen (TN, as N) ≤ 0.5 mg / L, Ammonia Nitrogen (NH3-N, inorganic nitrogen, as N) ≤ 0.5 mg / L, Total Phosphorus (TP, phosphate, as P) ≤ 15 mg / L, Suspended Solids (SS) ≤ 80 mg / L.

[0004] During the commissioning period, the non-discharge wastewater quality is as follows: pH value is approximately 11, chemical oxygen demand (CODCr) ≤ 30 mg / L, hydrazine (N2H4, as N) ≤ 500 mg / L, ammonia nitrogen (NH3-N, inorganic nitrogen, as N) ≤ 50 mg / L, total phosphorus (TP, phosphate, as P) ≤ 100 mg / L, and suspended solids (SS) ≤ 80 mg / L.

[0005] Therefore, it is evident that non-radioactive wastewater from nuclear power plants is characterized by alkalinity, low organic matter content, high nitrogen, and high phosphorus levels, making it impossible to achieve national or local emission standards through biological nitrogen and phosphorus removal. Furthermore, the quality of non-radioactive wastewater varies under different operating conditions. Failure to differentiate treatment based on water quality for different operating conditions will increase the amount of chemicals used, thereby increasing operating costs. Summary of the Invention

[0006] The purpose of this invention is to provide a non-radioactive wastewater treatment system for nuclear power plants. This system can not only effectively treat non-radioactive wastewater from nuclear power plants to meet discharge standards, but also differentiate between non-radioactive wastewater of different qualities, thereby reducing the amount of chemicals used and lowering operating costs.

[0007] This invention provides a non-radioactive wastewater treatment system for nuclear power plants, comprising an inlet pipeline, a selective wastewater collection unit, a wastewater treatment unit, and a drainage pipeline;

[0008] The selective wastewater collection unit includes multiple wastewater collection tanks, each including a first wastewater collection tank for collecting Class I non-emission wastewater, a second wastewater collection tank for collecting Class II non-emission wastewater, and a third wastewater collection tank for collecting Class III non-emission wastewater. The inlet pipeline is connected to the first, second, and third wastewater collection tanks respectively. Specifically, the first type of non-emission wastewater has a nitrogen content exceeding the nitrogen emission standard and a phosphorus content below the phosphorus emission standard; the second type of non-emission wastewater has a phosphorus content exceeding the phosphorus emission standard and a nitrogen content below the nitrogen emission standard; and the third type of non-emission wastewater has both a nitrogen content exceeding the nitrogen emission standard and a phosphorus content exceeding the phosphorus emission standard.

[0009] The wastewater treatment unit includes a reaction tank unit and a dosing unit. The reaction tank unit includes a pH adjustment tank, a primary chemical reaction tank, a secondary chemical reaction tank, a sedimentation and clarifier, and a final discharge tank connected in sequence. The first wastewater collection tank, the second wastewater collection tank, and the third wastewater collection tank are respectively connected to the pH adjustment tank, and the final discharge tank is connected to the drainage pipeline. The dosing unit includes an acid dosing unit for adding acid, an alkali dosing unit for adding alkali, an oxidizing dosing unit for adding oxidant, a phosphorus removal dosing unit for adding phosphorus removal agent, a coagulant aid dosing unit for adding coagulant aid, and a reducing dosing unit for adding reducing agent. The acid dosing unit and the alkali dosing unit are respectively connected to the pH adjustment tank and the final discharge tank. The oxidizing dosing unit and the phosphorus removal dosing unit are both connected to the primary chemical reaction tank. The coagulant aid dosing unit is connected to the secondary chemical reaction tank. The reducing dosing unit is connected between the final discharge tank and the drainage pipeline.

[0010] In one feasible embodiment, the HRT of the first and second wastewater collection tanks is 18H to 24H, and the HRT of the third wastewater collection tank is greater than that of the first and second wastewater collection tanks.

[0011] In one feasible embodiment, the pH adjustment tank, the primary chemical reaction tank, the secondary chemical reaction tank, and the final discharge tank are all equipped with mixing and stirring devices; the HRT (heating time) of the pH adjustment tank, the primary chemical reaction tank, and the secondary chemical reaction tank is 15 min to 20 min, and the load of the precipitator 314 is 3.0-5.0 m³. 3 / (m 2 ·h).

[0012] In one possible implementation, a first automatic valve is provided between the inlet pipe and the first wastewater collection tank, a second automatic valve is provided between the inlet pipe and the second wastewater collection tank, and a third automatic valve is provided between the inlet pipe and the third wastewater collection tank; the nuclear power plant non-radioactive wastewater treatment system further includes a control unit, an inlet water quality analyzer is provided on the inlet pipe, the inlet water quality analyzer is used to detect the COD, nitrogen content and phosphorus content of the non-radioactive wastewater, and the control unit is electrically connected to the inlet water quality analyzer, the first automatic valve, the second automatic valve and the third automatic valve respectively.

[0013] In one possible implementation, the control unit is also electrically connected to the oxidation dosing unit and the phosphorus removal dosing unit, respectively. The control unit is used to control the dosage of the oxidation dosing unit and the phosphorus removal dosing unit based on the COD, nitrogen content and phosphorus content of the non-discharged wastewater detected by the influent water quality analyzer.

[0014] In one possible implementation, the nuclear power plant non-radioactive wastewater treatment system further includes a recirculation pipeline, one end of which is connected to the drainage pipeline, and the other end of which is connected to the first wastewater collection tank, the second wastewater collection tank, and the third wastewater collection tank, respectively, to repeatedly treat unqualified non-radioactive wastewater.

[0015] In one possible implementation, a fourth automatic valve is provided on the drainage pipeline, and a fifth automatic valve is provided on the recirculation pipeline; the nuclear power plant non-radioactive wastewater treatment system also includes a control unit, and a drainage water quality analyzer is provided on the drainage pipeline. The control unit is electrically connected to the drainage water quality analyzer, the fourth automatic valve, and the fifth automatic valve, respectively.

[0016] In one possible implementation, the control unit is also electrically connected to the reduction dosing unit, and the control unit is used to control the dosage of the reduction dosing unit based on the residual chlorine concentration of the non-discharged wastewater detected by the wastewater quality analyzer.

[0017] In one possible implementation, the first wastewater collection tank, the second wastewater collection tank, and the third wastewater collection tank are each connected to the pH adjustment tank via a first transfer pump; the nuclear power plant non-radioactive wastewater treatment system further includes a bypass pipeline, one end of which is connected between the first transfer pump and the pH adjustment tank, and the other end of which is connected to the first wastewater collection tank, the second wastewater collection tank, and the third wastewater collection tank respectively; the bypass pipeline is used for wastewater transfer between the wastewater collection tanks to keep at least one of the wastewater collection tanks in an empty state, and the recirculation pipeline is used to return unqualified non-radioactive wastewater to the empty wastewater collection tank.

[0018] In one possible implementation, a first level sensor is provided on the first wastewater collection tank, a second level sensor is provided on the second wastewater collection tank, and a third level sensor is provided on the third wastewater collection tank. A sixth automatic valve is provided between the circulation return pipeline and the first wastewater collection tank, a seventh automatic valve is provided between the circulation return pipeline and the second wastewater collection tank, and an eighth automatic valve is provided between the circulation return pipeline and the third wastewater collection tank. The nuclear power plant non-radioactive wastewater treatment system also includes a control unit, which is electrically connected to the first level sensor, the second level sensor, the third level sensor, the sixth automatic valve, the seventh automatic valve, and the eighth automatic valve, respectively.

[0019] In one possible implementation, a first pH meter is installed on the pipeline between the pH adjustment tank and the primary chemical reaction tank, and a second pH meter is installed on the final discharge tank; the nuclear power plant non-radioactive wastewater treatment system further includes a control unit, which is electrically connected to the first pH meter, the second pH meter, the acid dosing unit, and the alkali dosing unit, respectively, and the control unit is used to control the dosage of the acid dosing unit and the alkali dosing unit according to the pH value measured by the first pH meter and the second pH meter.

[0020] In one possible implementation, the number of wastewater treatment units is at least two sets, and the at least two sets of wastewater treatment units are arranged in parallel.

[0021] The nuclear power plant non-radioactive wastewater treatment system provided by this invention, through the setting of a reaction tank unit and a chemical dosing unit, firstly uses acid dosing and alkali dosing units to perform acid and alkali dosing in the pH adjustment tank, adjusting the pH value of the non-radioactive wastewater to a suitable pH for subsequent reactions; then, an oxidizing dosing unit adds an oxidant to the primary chemical reaction tank, causing the ammonia nitrogen in the non-radioactive wastewater to be oxidized into nitrogen gas and released through a redox reaction, and also oxidizing and removing COD from the non-radioactive wastewater; simultaneously, a phosphorus removal dosing unit adds a phosphorus removal agent to the primary chemical reaction tank, converting total phosphorus in the non-radioactive wastewater into phosphate precipitation, and flocculating suspended solids in the non-radioactive wastewater; finally, a coagulation aid dosing unit is used... A coagulant aid is added to the secondary chemical reaction tank to cause the phosphate precipitates and flocculated suspended solids in the non-emission wastewater to coagulate into larger floc particles. After the non-emission wastewater flows to the sedimentation and clarification tank, the phosphate precipitates and suspended floc particles settle under gravity, achieving solid-liquid separation. The non-emission wastewater after solid-liquid separation enters the final discharge tank, where acid and alkali dosing units are used to adjust the pH value of the non-emission wastewater to meet the standard. Then, a reducing agent is added to the non-emission wastewater using a reduction dosing unit, and the residual chlorine concentration of the non-emission wastewater is adjusted to meet the standard through a redox reaction. The treated non-emission wastewater that meets the standards is finally discharged through the drainage pipeline.

[0022] Meanwhile, by setting up a first, second, and third wastewater collection pond, different non-radioactive wastewater of varying qualities is collected in each pond. This allows for differentiated treatment of non-radioactive wastewater of different qualities, thereby reducing the amount of oxidants, phosphorus removal agents, and other chemicals used. This nuclear power plant non-radioactive wastewater treatment system not only effectively treats non-radioactive wastewater to meet discharge standards but also differentiates the treatment of non-radioactive wastewater of different qualities, thus helping to reduce the amount of chemicals used and lower operating costs. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the non-radioactive wastewater treatment system of a nuclear power plant in an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the control logic of the control unit in an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the structure of a non-radioactive wastewater treatment system for nuclear power plants in another embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the structure of a non-radioactive wastewater treatment system for nuclear power plants in another embodiment of the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0029] The directional terms such as "up," "down," "left," "right," "front," "back," "top," and "bottom" (if present) used in the specification and claims of this invention are defined by the position of the structures in the drawings and the relative positions of the structures, and are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of directional terms should not limit the scope of protection claimed by this invention.

[0030] like Figure 1 As shown, the nuclear power plant non-radioactive wastewater treatment system provided in this embodiment of the invention includes an inlet pipe 1, a selective wastewater collection unit 2, a wastewater treatment unit 3, and a drainage pipe 4.

[0031] The selective wastewater collection unit 2 includes multiple wastewater collection tanks, including a first wastewater collection tank 21 for collecting Class I non-radioactive wastewater (i.e., non-radioactive production wastewater), a second wastewater collection tank 22 for collecting Class II non-radioactive wastewater, and a third wastewater collection tank 23 for collecting Class III non-radioactive wastewater. The inlet pipe 1 is connected to the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23, respectively. The Class I non-radioactive wastewater has a nitrogen content exceeding the nitrogen emission standard and a phosphorus content below the phosphorus emission standard; the Class II non-radioactive wastewater has a phosphorus content exceeding the phosphorus emission standard and a nitrogen content below the nitrogen emission standard; and the Class III non-radioactive wastewater has a nitrogen content exceeding the nitrogen emission standard and a phosphorus content exceeding the phosphorus emission standard. The nitrogen emission standard and phosphorus emission standard can be determined according to national or local emission standards. Among them, the first and second categories of non-radioactive wastewater are generally non-radioactive wastewater generated during the normal operation of a nuclear power plant, while the third category of non-radioactive wastewater is generally non-radioactive wastewater generated during the commissioning of a nuclear power plant.

[0032] Wastewater treatment unit 3 includes a reaction tank unit and a dosing unit. The reaction tank unit includes a pH adjustment tank 311, a primary chemical reaction tank 312, a secondary chemical reaction tank 313, a sedimentation and clarification tank 314, and a final discharge tank 315 connected in sequence (specifically, the pH adjustment tank 311, the primary chemical reaction tank 312, the secondary chemical reaction tank 313, the sedimentation and clarification tank 314, and the final discharge tank 315 are connected to each other by pipelines). The first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 are connected to the pH adjustment tank 311 by pipelines. The final discharge tank 315 is connected to the drainage pipeline 4. The dosing unit includes an acid dosing unit 321 for adding acid, an alkali dosing unit 322 for adding alkali, an oxidation dosing unit 323 for adding oxidant, a phosphorus removal dosing unit 324 for adding phosphorus removal agent, a coagulant aid dosing unit 325 for adding coagulant aid, and a reduction dosing unit 326 for adding reducing agent. The acid dosing unit 321 and the alkali dosing unit 322 are respectively connected to the pH adjustment tank 311 and the final discharge tank 315. The oxidation dosing unit 323 and the phosphorus removal dosing unit 324 are both connected to the primary chemical reaction tank 312. The coagulant aid dosing unit 325 is connected to the secondary chemical reaction tank 313. The reduction dosing unit 326 is connected between the final discharge tank 315 and the drainage pipe 4 (specifically, it is connected to the pipe between the final discharge tank 315 and the drainage pipe 4). The acid dosing unit 321 is used to add acid to the pH adjustment tank 311 and the final discharge tank 315; the alkali dosing unit 322 is used to add alkali to the pH adjustment tank 311 and the final discharge tank 315; the oxidation dosing unit 323 is used to add oxidant to the primary chemical reaction tank 312; the phosphorus removal dosing unit 324 is used to add phosphorus removal agent to the primary chemical reaction tank 312; and the reduction dosing unit 326 is used to add reducing agent to the pipeline between the final discharge tank 315 and the drainage pipeline 4.

[0033] The nuclear power plant non-radioactive wastewater treatment system provided by this invention, by setting up a reaction tank unit and a dosing unit, firstly, acid dosing unit 321 and alkali dosing unit 322 are used to douse the pH adjustment tank 311 with acid and alkali to adjust the pH value of the non-radioactive wastewater to a suitable pH (e.g., 6.0-7.0) for subsequent reactions; then, oxidant is added to the primary chemical reaction tank 312 by oxidation dosing unit 323, so that the ammonia nitrogen in the non-radioactive wastewater is oxidized into nitrogen gas through a redox reaction and escaped, and the COD in the non-radioactive wastewater is oxidized and removed. At the same time, phosphorus removal dosing unit 324 is used to add phosphorus removal agent to the primary chemical reaction tank 312, so that the total phosphorus in the non-radioactive wastewater is converted into phosphate precipitation and the suspended solids (SS) in the non-radioactive wastewater are flocculated; then, a coagulation aid dosing unit is used. 325. A coagulant is added to the secondary chemical reaction tank 313 to cause the phosphate precipitate and flocculated suspended solids in the non-discharge wastewater to agglomerate into larger floc particles. After the non-discharge wastewater flows to the sedimentation and clarification tank 314, the phosphate precipitate and suspended floc particles settle under gravity, achieving solid-liquid separation. The non-discharge wastewater after solid-liquid separation enters the final discharge tank 315. The final discharge tank 315 is treated with acid and alkali by acid dosing unit 321 and alkali dosing unit 322 to adjust the pH value of the non-discharge wastewater to meet the standard (e.g., 7.5-8.5). Then, a reducing agent is added to the non-discharge wastewater by reduction dosing unit 326 to adjust the residual chlorine concentration of the non-discharge wastewater to meet the standard through oxidation-reduction reaction. The treated non-discharge wastewater that meets the standard is finally discharged through the drainage pipe 4.

[0034] Meanwhile, by setting up a first wastewater collection tank 21, a second wastewater collection tank 22, and a third wastewater collection tank 23, non-discharged wastewater of different water qualities can be collected in the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 respectively, thereby enabling the non-discharged wastewater of different water qualities to be treated separately, thereby reducing the amount of oxidants, phosphorus removal agents, and other agents used. Specifically, the non-emission wastewater in the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 is generally treated separately (i.e., the non-emission wastewater in the three wastewater collection tanks is generally not mixed together and treated simultaneously). When the non-emission wastewater in the first wastewater collection tank 21 is being treated, since the nitrogen content of the first type of non-emission wastewater collected therein exceeds the nitrogen emission standard and the phosphorus content is lower than the phosphorus emission standard, no phosphorus removal agent needs to be added during treatment. When the non-emission wastewater in the second wastewater collection tank 22 is being treated, since the phosphorus content of the second type of non-emission wastewater collected therein exceeds the phosphorus emission standard and the nitrogen content is lower than the nitrogen emission standard, no oxidant needs to be added during treatment. When the non-emission wastewater in the third wastewater collection tank 23 is being treated, since the nitrogen content of the third type of non-emission wastewater collected therein exceeds the nitrogen emission standard and the phosphorus content exceeds the phosphorus emission standard, both oxidant and phosphorus removal agent need to be added during treatment. Therefore, by treating non-emission wastewater of different qualities separately, the amount of oxidants, phosphorus removal agents, and other chemicals used can be reduced (it's easy to understand that if various types of non-emission wastewater of different qualities are mixed together for treatment, the nitrogen and phosphorus content of the mixed wastewater will exceed the discharge standards, so oxidants and phosphorus removal agents must always be added simultaneously during treatment). Furthermore, by setting up multiple wastewater collection ponds, these ponds can serve as backups for each other, allowing for wastewater release in emergencies to ensure the safety of the nuclear power plant operation.

[0035] The nuclear power plant's non-radioactive wastewater treatment system can not only effectively treat the non-radioactive wastewater to meet discharge standards, but also differentiate between non-radioactive wastewater of different qualities, thereby reducing the amount of chemicals used and lowering operating costs.

[0036] In one embodiment, the acid solution is preferably hydrochloric acid, the alkaline solution is preferably sodium hydroxide solution, the oxidant is preferably sodium hypochlorite solution, the phosphorus removal agent is preferably polyferric sulfate solution, the coagulant aid is preferably anionic polyacrylamide solution, and the reducing agent is preferably sodium bisulfite solution.

[0037] As one implementation method, the HRT (Hydraulic Retention Time) of the first wastewater collection tank 21 and the second wastewater collection tank 22 is preferably 18H to 24H, and the HRT of the third wastewater collection tank 23 is greater than that of the first wastewater collection tank 21 and the second wastewater collection tank 22 (specifically, in this embodiment, the HRT of the third wastewater collection tank 23 is twice that of the first wastewater collection tank 21 and the second wastewater collection tank 22). Since the third wastewater collection tank 23 collects non-discharge wastewater generated during the commissioning period with a higher waste content, increasing the HRT of the third wastewater collection tank 23 can improve its wastewater treatment effect.

[0038] In one implementation, the volume of the third wastewater collection tank 23 is larger than the volumes of the first wastewater collection tank 21 and the second wastewater collection tank 22 (specifically, in this embodiment, the volumes of the first wastewater collection tank 21 and the second wastewater collection tank 22 are equal, and the volume of the third wastewater collection tank 23 is twice the volume of the first wastewater collection tank 21 and the second wastewater collection tank 22). Since the third wastewater collection tank 23 is used to collect a large amount of non-discharge wastewater generated instantaneously during commissioning, its volume is set to be relatively large to cope with emergency discharge conditions.

[0039] In one implementation, the pH adjustment tank 311, primary chemical reaction tank 312, secondary chemical reaction tank 313, and final discharge tank 315 are all equipped with mixing and stirring devices (not shown in the figure); the HRT of the pH adjustment tank 311, primary chemical reaction tank 312, and secondary chemical reaction tank 313 is preferably 15 min to 20 min, and the load of the sedimentation and clarification tank 314 is preferably 3.0-5.0 m³ / h. 3 / (m 2 •h) to improve wastewater treatment efficiency.

[0040] In one implementation, each dosing unit (including acid dosing unit 321, alkali dosing unit 322, oxidation dosing unit 323, phosphorus removal dosing unit 324, coagulation aid dosing unit 325, and reduction dosing unit 326) includes a solution tank (not shown) and a variable frequency metering pump (not shown). The solution tank is used to store the corresponding reagents, and the variable frequency metering pump is connected between the solution tank and the corresponding reaction tank to add reagents to the reaction tank. Specifically, since both the acid dosing unit 321 and the alkali dosing unit 322 are connected to the pH adjustment tank 311 and the final discharge tank 315 respectively, the pH adjustment tank 311 and the final discharge tank 315 can share the same acid dosing unit 321 and the same alkali dosing unit 322 (i.e., the acid dosing unit 321 only needs to be equipped with one solution tank and two variable frequency metering pumps respectively connected to the pH adjustment tank 311 and the final discharge tank 315; similarly, the alkali dosing unit 322 only needs to be equipped with one solution tank and two variable frequency metering pumps respectively connected to the pH adjustment tank 311 and the final discharge tank 315). Of course, in other embodiments, two acid dosing units 321 and two alkali dosing units 322 can also be provided, with the pH adjustment tank 311 and the final discharge tank 315 connected to different acid dosing units 321 and alkali dosing units 322 respectively.

[0041] like Figure 1 As shown, in one embodiment, the non-radioactive wastewater treatment system of a nuclear power plant also includes a first transfer pump 51. The first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 are respectively connected to the pH adjustment tank 311 via the first transfer pump 51. Specifically, in this embodiment, there is one first transfer pump 51, which is simultaneously connected to the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23.

[0042] like Figure 3 As shown, in another embodiment, there are three first transfer pumps 51, which correspond to the first wastewater collection tank 21, the second wastewater collection tank 22 and the third wastewater collection tank 23 respectively. Each first transfer pump 51 is connected between the corresponding wastewater collection tank and the pH adjustment tank 311.

[0043] like Figure 4 As shown, in another embodiment, there are three first transfer pumps 51. These three first transfer pumps 51 correspond to the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23, respectively. Each first transfer pump 51 is connected between the corresponding wastewater collection tank and the pH adjustment tank 311, and each first transfer pump 51 is also connected to the other two wastewater collection tanks to achieve mutual backup among the multiple first transfer pumps 51.

[0044] like Figure 1As shown, in one embodiment, the non-radioactive wastewater treatment system of the nuclear power plant also includes a second transfer pump 52, which is connected between the final discharge pool 315 and the drainage pipeline 4, and a reduction dosing unit 326 is connected to the pipeline between the final discharge pool 315 and the second transfer pump 52.

[0045] like Figure 1 and Figure 2 As shown, in one embodiment, a first automatic valve 61 is provided between the inlet pipe 1 and the first wastewater collection tank 21, a second automatic valve 62 is provided between the inlet pipe 1 and the second wastewater collection tank 22, and a third automatic valve 63 is provided between the inlet pipe 1 and the third wastewater collection tank 23; the first automatic valve 61, the second automatic valve 62 and the third automatic valve 63 are used to control the flow direction of non-discharge wastewater in the inlet pipe 1. The non-radioactive wastewater treatment system of the nuclear power plant also includes a control unit 8, which can be a PLC control device. An inlet water quality analyzer 71 is installed on the inlet water pipeline 1. The inlet water quality analyzer 71 is an online water quality analyzer used to detect the COD (chemical oxygen demand), nitrogen content, and phosphorus content of the non-radioactive wastewater in the inlet water pipeline 1. The control unit 8 is electrically connected to the inlet water quality analyzer 71, the first automatic valve 61, the second automatic valve 62, and the third automatic valve 63, respectively. The control unit 8 is used to control the opening and closing of the first automatic valve 61, the second automatic valve 62, and the third automatic valve 63 according to the water quality of the non-radioactive wastewater measured by the inlet water quality analyzer 71 (i.e., automatically identifying which category of non-radioactive wastewater in the inlet water pipeline 1 belongs to: Class I, Class II, or Class III non-radioactive wastewater), so that the non-radioactive wastewater in the inlet water pipeline 1 automatically flows to the corresponding wastewater collection tank, thereby realizing the automated control operation of the system.

[0046] like Figure 1 and Figure 2 As shown, in one embodiment, the control unit 8 is also electrically connected to the oxidation dosing unit 323 and the phosphorus removal dosing unit 324 respectively. The control unit 8 is used to control the dosing amount of the oxidation dosing unit 323 and the phosphorus removal dosing unit 324 according to the COD, nitrogen content and phosphorus content of the non-discharged wastewater detected by the influent water quality analyzer 71.

[0047] Specifically, a flow meter 75 is installed on the pipeline between the first delivery pump 51 and the pH adjustment tank 311, and the control unit 8 is also electrically connected to the flow meter 75. The control unit 8 calculates the dosage of the oxidation dosing unit 323 based on the nitrogen content of the non-discharge wastewater detected by the influent water quality analyzer 71, the flow rate detected by the flow meter 75, and the designed effluent ammonia nitrogen index (i.e., nitrogen emission index value; where the COD of the non-discharge wastewater is generally within the emission limit). The control unit 8 calculates the dosage of the phosphorus removal dosing unit 324 based on the phosphorus content of the non-discharge wastewater detected by the influent water quality analyzer 71, the flow rate detected by the flow meter 75, and the designed effluent total phosphorus index (i.e., phosphorus emission index value). At the same time, the control unit 8 is also electrically connected to the coagulant aid dosing unit 325, and the control unit 8 calculates the dosage of the coagulant aid dosing unit 325 based on the flow rate detected by the flow meter 75 and the coagulant concentration (generally 3-4 mg / L).

[0048] like Figure 1 As shown, in one implementation method, the non-radioactive wastewater treatment system of a nuclear power plant also includes a recirculation pipeline 33. One end of the recirculation pipeline 33 is connected to the drainage pipeline 4, and the other end of the recirculation pipeline 33 is connected to the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23, respectively, to repeatedly treat unqualified non-radioactive wastewater. Specifically, when the water quality of the treated non-radioactive wastewater does not meet the standards, the non-radioactive wastewater can be returned to the first wastewater collection tank 21, the second wastewater collection tank 22, or the third wastewater collection tank 23 through the recirculation pipeline 33 for further treatment, thereby repeatedly treating the non-radioactive wastewater to ensure that the water quality meets the standards. At the same time, unreacted reagents in the system can be reused during the recycling process, thereby further reducing the dosage of oxidants, phosphorus removal agents, etc., and saving operating reagent costs.

[0049] like Figure 1 and Figure 2 As shown, in one embodiment, a fourth automatic valve 64 is provided on the drainage pipe 4. The fourth automatic valve 64 is located downstream of the connection point between the circulation return pipe 33 and the drainage pipe 4. A fifth automatic valve 65 is provided on the circulation return pipe 33. A drainage water quality analyzer 72 is provided on the drainage pipe 4. The drainage water quality analyzer 72 is an online water quality analyzer used to detect residual chlorine, COD, nitrogen content (ammonia nitrogen, total nitrogen), phosphorus content (total phosphorus), and suspended solids (SS) in the non-discharge wastewater in the drainage pipe 4. The control unit 8 is electrically connected to the drainage water quality analyzer 72, the fourth automatic valve 64, and the fifth automatic valve 65, respectively. The control unit 8 is used to determine whether the water quality of the non-discharge wastewater in the drainage pipe 4 meets the standards based on the water quality measured by the drainage water quality analyzer 72, thereby controlling the opening and closing of the fourth automatic valve 64 and the fifth automatic valve 65, and thus controlling the flow direction of the non-discharge wastewater to achieve automated control operation of the system.

[0050] Specifically, the opening and closing states of the fourth automatic valve 64 and the fifth automatic valve 65 are opposite. When the wastewater quality analyzer 72 measures that all water quality indicators of the non-discharge wastewater meet the standards, the control unit 8 controls the fourth automatic valve 64 to open and the fifth automatic valve 65 to close, allowing the non-discharge wastewater to be discharged through the drainage pipe 4. When the wastewater quality analyzer 72 measures that at least one water quality indicator of the non-discharge wastewater fails to meet the standards, the control unit 8 controls the fourth automatic valve 64 to close and the fifth automatic valve 65 to open, allowing the non-discharge wastewater in the drainage pipe 4 to flow back to the corresponding wastewater collection tank through the circulation return pipe 33 for repeated treatment.

[0051] As one implementation method, during operation, at least one of the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 remains in an empty state (i.e., it is in an vacant state, and no non-discharge wastewater is stored in the wastewater collection tank); the non-discharge wastewater can be returned to the empty wastewater collection tank of the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 through the circulation return pipeline 33, so as to avoid the return wastewater from mixing with untreated wastewater and reduce the difficulty of treatment.

[0052] like Figure 1 As shown, in one embodiment, the non-radioactive wastewater treatment system of the nuclear power plant also includes a bypass pipeline 34. One end of the bypass pipeline 34 is connected to the pipeline between the first transfer pump 51 and the pH adjustment tank 311, and the other end of the bypass pipeline 34 is connected to the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23, respectively. The bypass pipeline 34 is used for wastewater transfer between the wastewater collection tanks (i.e., transferring non-radioactive wastewater from one wastewater collection tank to another wastewater collection tank through the first transfer pump 51 and the bypass pipeline 34) to keep at least one wastewater collection tank in an empty state. The recirculation pipeline 33 is used to return unqualified non-radioactive wastewater to the empty wastewater collection tank. Since at least one of the wastewater collection pools is empty after the wastewater is transferred to the empty wastewater collection pool, the circulating return pipeline 33 can return the non-compliant non-release wastewater to the empty wastewater collection pool, which facilitates wastewater treatment. In addition, in an emergency, a large amount of wastewater can be discharged into the empty wastewater collection pool, thereby ensuring the operational safety of the nuclear power plant.

[0053] like Figure 1 and Figure 2As shown, in one embodiment, a first level sensor (not shown) is provided on the first wastewater collection tank 21, a second level sensor (not shown) is provided on the second wastewater collection tank 22, and a third level sensor (not shown) is provided on the third wastewater collection tank 23. The first, second, and third level sensors are used to detect the liquid level heights of the first, second, and third wastewater collection tanks 21, 22, and 23, respectively. A sixth automatic valve 66 is provided between the circulation return pipeline 33 and the first wastewater collection tank 21, a seventh automatic valve 67 is provided between the circulation return pipeline 33 and the second wastewater collection tank 22, and an eighth automatic valve 68 is provided between the circulation return pipeline 33 and the third wastewater collection tank 23. The sixth, seventh, and eighth automatic valves 66, 67, and 68 are used to control the flow direction of the non-discharge wastewater returning in the circulation return pipeline 33. The control unit 8 is electrically connected to the first liquid level sensor, the second liquid level sensor, the third liquid level sensor, the sixth automatic valve 66, the seventh automatic valve 67, and the eighth automatic valve 68, respectively. It determines which wastewater collection tank is empty by measuring the liquid level values ​​of the first liquid level sensor, the second liquid level sensor, and the third liquid level sensor, and then controls the automatic valve connected to the empty tank to open and close the other automatic valves, so that the non-discharged wastewater in the circulation return pipeline 33 flows back to the empty tank.

[0054] like Figure 1 As shown, in one embodiment, the bypass pipe 34 is first connected to the circulation return pipe 33, and then connected to the first wastewater collection tank 21, the second wastewater collection tank 22 and the third wastewater collection tank 23 through the circulation return pipe 33 respectively.

[0055] like Figure 1 and Figure 2 As shown, in one embodiment, the control unit 8 is also electrically connected to the reduction dosing unit 326. The control unit 8 is used to control the dosage of the reduction dosing unit 326 based on the residual chlorine concentration of the non-discharged wastewater detected by the wastewater quality analyzer 72. Specifically, the residual chlorine concentration of the non-discharged wastewater is preferably controlled at ≤1.0 mg / L.

[0056] like Figure 1 and Figure 2 As shown, in one embodiment, a first pH meter 73 is installed on the pipeline between the pH adjustment tank 311 and the primary chemical reaction tank 312, and a second pH meter 74 is installed on the final discharge tank 315. The first pH meter 73 and the second pH meter 74 are used to detect the pH value of the non-discharge wastewater at the corresponding locations. The control unit 8 is electrically connected to the first pH meter 73, the second pH meter 74, the acid dosing unit 321, and the alkali dosing unit 322, respectively. The control unit 8 is used to control the dosage of the acid dosing unit 321 and the alkali dosing unit 322 according to the pH value measured by the first pH meter 73 and the second pH meter 74.

[0057] Specifically, the pH at the first pH meter 73 is generally controlled at 6.0-7.0 to adjust the pH of the non-discharge wastewater to a suitable pH for subsequent reactions (such as redox reactions, phosphorus removal agent reactions, flocculation reactions, etc.); the pH at the second pH meter 74 is generally controlled at 7.5-8.5 to ensure that the pH of the non-discharge wastewater meets the discharge standards.

[0058] like Figure 1 As shown, in one embodiment, the wastewater treatment unit 3 is a set. In other embodiments, the wastewater treatment unit 3 is at least two sets, which are arranged in parallel (i.e., at least two sets of wastewater treatment units 3 are connected end to end). By setting multiple sets of wastewater treatment units 3, on the one hand, the treatment efficiency can be improved (for example, different wastewater treatment units 3 treat non-discharge wastewater in different wastewater collection tanks respectively; or, different wastewater treatment units 3 can also treat non-discharge wastewater in the same wastewater collection tank at the same time), and on the other hand, they can serve as mutual backups.

[0059] As one implementation method, the workflow of the non-radioactive wastewater treatment system of this nuclear power plant is as follows:

[0060] (1) Depending on the water quality, the non-discharged wastewater in the inlet pipe 1 enters the first wastewater collection tank 21 through the first automatic valve 61, or the second wastewater collection tank 22 through the second automatic valve 62, or the third wastewater collection tank 23 through the third automatic valve 63, and then enters the pH adjustment tank 311 through the first transfer pump 51. In the pH adjustment tank 311, under the dosing of the acid dosing unit 321 and the alkali dosing unit 322 and the regulation of the control unit 8, the pH of the non-discharged wastewater is adjusted to 6.0-7.0 through the neutralization reaction to facilitate the subsequent reaction.

[0061] (2) The non-discharged wastewater flows by gravity to the primary chemical reaction tank 312. Under the dosing of the oxidation dosing unit 323 and the regulation of the control unit 8, the ammonia nitrogen in the non-discharged wastewater is oxidized into nitrogen gas and released through the oxidation-reduction reaction, and the COD in the non-discharged wastewater is oxidized and removed. At the same time, under the dosing of the phosphorus removal dosing unit 324 and the regulation of the control unit 8, the total phosphorus in the non-discharged wastewater is converted into phosphate precipitate through the precipitation reaction, and the suspended solids (SS) in the non-discharged wastewater are flocculated.

[0062] (3) The non-discharged wastewater flows by gravity to the secondary chemical reaction tank 313. Under the dosing of the coagulation aid dosing unit 325 and the regulation of the control unit 8, the phosphate precipitates and flocculated suspended matter in the non-discharged wastewater are condensed into floc particles with larger particle size.

[0063] (4) Non-discharged wastewater flows by gravity into sedimentation clarifier 314. Under the action of gravity, phosphate precipitates and suspended floc particles settle, achieving solid-liquid separation. The precipitate in sedimentation clarifier 314 is then treated as sludge.

[0064] (5) The non-discharged wastewater flows by gravity to the final discharge tank 315. Under the dosing of the acid dosing unit 321 and the alkaline dosing unit 322 and the regulation of the control unit 8, the pH of the non-discharged wastewater is adjusted to 7.5-8.5 through neutralization reaction. Then, the reducing agent is added to the non-discharged wastewater by the reducing dosing unit 326. The residual chlorine concentration of the non-discharged wastewater is adjusted to meet the standard through oxidation-reduction reaction, such as residual chlorine concentration ≤1.0mg / L.

[0065] (6) The second transfer pump 52 transports the non-radioactive wastewater in the final discharge pool 315 to the drainage pipeline 4. If the non-radioactive wastewater being treated at this time is non-radioactive wastewater generated during the normal operation of the nuclear power plant, it can generally meet the standards after one treatment. After the treated non-radioactive wastewater passes the test of the drainage water quality analyzer 72, it can be discharged through the fourth automatic valve 64.

[0066] If the non-emission wastewater being treated at this time is generated during the commissioning of the nuclear power plant, it generally cannot meet the standards after a single treatment due to the high content of ammonia nitrogen and phosphorus. At this time, the non-emission wastewater after treatment fails the test by the drainage water quality analyzer 72. The control unit 8 controls the fourth automatic valve 64 to close and the fifth automatic valve 65 to open, so that the non-emission wastewater in the drainage pipeline 4 is returned to the corresponding wastewater collection tank through the circulation return pipeline 33. The non-emission wastewater is then treated again through the above steps (2) to (5). After at least two cycles of repeated treatment, the non-emission wastewater meets the standards and is then discharged through the fourth automatic valve 64. The secondary circulation treatment can further utilize the unreacted oxidant, phosphorus removal agent, etc., added in excess during the primary treatment process to achieve the effect of reducing the dosage.

[0067] The nuclear power plant non-radioactive wastewater treatment system provided in this embodiment of the invention, by setting up a reaction tank unit and a dosing unit, firstly uses acid dosing unit 321 and alkali dosing unit 322 to dosing acid and alkali in pH adjustment tank 311 to adjust the pH value of the non-radioactive wastewater to a suitable pH for subsequent reactions; then, using oxidation dosing unit 323 to add oxidant to primary chemical reaction tank 312, so that ammonia nitrogen in non-radioactive wastewater is oxidized into nitrogen gas and released through oxidation-reduction reaction, and COD in non-radioactive wastewater is oxidized and removed; at the same time, using phosphorus removal dosing unit 324 to add phosphorus removal agent to primary chemical reaction tank 312, converting total phosphorus in non-radioactive wastewater into phosphate precipitation, and flocculating suspended solids (SS) in non-radioactive wastewater; then using coagulation aid dosing unit... Yuan 325 adds a coagulant aid to the secondary chemical reaction tank 313, causing the phosphate precipitate and flocculated suspended solids in the non-emission wastewater to agglomerate into larger floc particles. After the non-emission wastewater flows to the sedimentation and clarification tank 314, the phosphate precipitate and suspended floc particles settle under gravity, achieving solid-liquid separation. The non-emission wastewater after solid-liquid separation enters the final discharge tank 315, where acid dosing unit 321 and alkali dosing unit 322 are used to adjust the pH value of the non-emission wastewater to meet the standard. Then, reducing agent is added to the non-emission wastewater using the reduction dosing unit 326, and the residual chlorine concentration of the non-emission wastewater is adjusted to meet the standard through an oxidation-reduction reaction. The treated non-emission wastewater that meets the standard is finally discharged through the drainage pipe 4.

[0068] Meanwhile, by setting up a first wastewater collection tank 21, a second wastewater collection tank 22, and a third wastewater collection tank 23, non-discharged wastewater of different water qualities can be collected in the first wastewater collection tank 21, the second wastewater collection tank 22, and the third wastewater collection tank 23 respectively, thereby enabling the non-discharged wastewater of different water qualities to be treated separately, thereby reducing the amount of oxidants, phosphorus removal agents, and other agents used.

[0069] This nuclear power plant's non-radioactive wastewater treatment system not only effectively treats non-radioactive wastewater to meet discharge standards, but also differentiates between different types of wastewater, reducing chemical usage and operating costs. Furthermore, the system employs the same wastewater treatment process and equipment with varying control methods depending on the nuclear power unit's commissioning and operational status, ensuring compliance while minimizing equipment investment and floor space requirements. Moreover, the system boasts excellent automatic control and regulation capabilities, making it suitable for treating non-radioactive wastewater of varying qualities from nuclear power units.

[0070] Example 1

[0071] A nuclear power plant has an average non-radiative wastewater treatment capacity of 50 m³. 3The HRT (Heat Reduction Time) of the first and second wastewater collection tanks is 20 hours, the HRT of the third wastewater collection tank is 40 hours, the HRT of the pH adjustment tank, the primary chemical reaction tank, and the secondary chemical reaction tank is 18 minutes, and the load of the sedimentation and clarification tank is 4.0 m³ / h. 3 / (m 2 •h). Acid dosing uses 31% hydrochloric acid, alkali dosing uses 32% sodium hydroxide, oxidizing dosing uses 10% sodium hypochlorite solution, reducing dosing uses 10% sodium bisulfite solution, phosphorus removal dosing uses 13% ferric chloride solution, and coagulant dosing uses 0.1% anionic polyacrylamide. All dosing pumps are frequency converter controlled. During normal operation, the dosing rate of the oxidizing dosing pump is calculated based on the flow meter reading, ammonia nitrogen content, and the design wastewater ammonia nitrogen index (8 mg / L); the dosing rate of the phosphorus removal dosing pump is calculated based on the flow meter reading, total phosphorus content, and the design wastewater total phosphorus index (0.5 mg / L); the control range of the first pH meter is 6.0-7.0, the control range of the second pH meter is 7.5-8.5, the residual chlorine concentration is controlled within the range of ≤1.0 mg / L, and the coagulant dosing concentration is 3.0 mg / L. During commissioning and operation, the wastewater undergoes secondary recycling treatment. The primary treatment removes 50% of the ammonia nitrogen and 50% of the total phosphorus, while the secondary recycling treatment removes the remaining 50% of the ammonia nitrogen and 50% of the total phosphorus. The treated effluent meets the Class I standards for the second time period in Guangdong Province's "Water Pollutant Discharge Limits" (DB 44 / 26-2001), specifically as follows:

[0072]

[0073]

[0074] Example 2

[0075] A nuclear power plant has an average non-radiative wastewater treatment capacity of 50 m³. 3 The HRT (Heat Reduction Time) of the first and second wastewater collection tanks is 20 hours, the HRT of the third wastewater collection tank is 40 hours, the HRT of the pH adjustment tank, the primary chemical reaction tank, and the secondary chemical reaction tank is 20 minutes, and the load of the sedimentation and clarification tank is 3.0 m³ / h. 3 / (m 2•h). Acid dosing uses 31% hydrochloric acid, alkali dosing uses 32% sodium hydroxide, oxidizing dosing uses 10% sodium hypochlorite solution, reducing dosing uses 10% sodium bisulfite solution, phosphorus removal dosing uses 13% ferric chloride solution, and coagulant dosing uses 0.2% anionic polyacrylamide. All dosing pumps are frequency converter controlled. During normal operation, the dosing rate of the oxidizing dosing pump is calculated based on the flow meter reading, ammonia nitrogen content, and the design wastewater ammonia nitrogen index (1 mg / L); the dosing rate of the phosphorus removal dosing pump is calculated based on the flow meter reading, total phosphorus content, and the design wastewater total phosphorus index (0.3 mg / L); the control range of the first pH meter is 6.0-7.0, the control range of the second pH meter is 7.5-8.5, the residual chlorine concentration is controlled within the range of ≤1.0 mg / L, and the coagulant dosing concentration is 4.0 mg / L. During commissioning and operation, the wastewater undergoes secondary recycling treatment. The primary treatment removes 50% of the ammonia nitrogen and 50% of the total phosphorus, while the secondary recycling treatment removes the remaining 50% of the ammonia nitrogen and 50% of the total phosphorus. The treated effluent meets the relevant indicators of Zhejiang Province's "Discharge Standard of Major Water Pollutants for Urban Wastewater Treatment Plants" (DB 33 / 2169-2018), with specific indicators as follows:

[0076] Serial Number Project Name Water quality indicators 1 pH 6-9 2 Suspended matter SS ≤10mg / L 3 COD ≤30mg / L 4 Ammonia nitrogen (as N) ≤1.5(3)mg / L 5 Phosphate (as P) ≤0.3mg / L

[0077] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A non-radioactive wastewater treatment system for nuclear power plants, characterized in that, It includes an inlet pipe (1), a selective wastewater collection unit (2), a wastewater treatment unit (3), and a drainage pipe (4). The selective wastewater collection unit (2) includes multiple wastewater collection tanks, each including a first wastewater collection tank (21) for collecting first-class non-emission wastewater, a second wastewater collection tank (22) for collecting second-class non-emission wastewater, and a third wastewater collection tank (23) for collecting third-class non-emission wastewater. The inlet pipe (1) is connected to the first wastewater collection tank (21), the second wastewater collection tank (22), and the third wastewater collection tank (23), respectively. The first-class non-emission wastewater has a nitrogen content exceeding the nitrogen emission index value and a phosphorus content lower than the phosphorus emission index value; the second-class non-emission wastewater has a phosphorus content exceeding the phosphorus emission index value and a nitrogen content lower than the nitrogen emission index value; and the third-class non-emission wastewater has a nitrogen content exceeding the nitrogen emission index value and a phosphorus content exceeding the phosphorus emission index value. The wastewater treatment unit (3) includes a reaction tank unit and a dosing unit. The reaction tank unit includes a pH adjustment tank (311), a primary chemical reaction tank (312), a secondary chemical reaction tank (313), a sedimentation clarifier (314), and a final discharge tank (315) connected in sequence. The first wastewater collection tank (21), the second wastewater collection tank (22), and the third wastewater collection tank (23) are respectively connected to the pH adjustment tank (311), and the final discharge tank (315) is connected to the drainage pipeline (4). The dosing unit includes an acid dosing unit (321) for adding acid, an alkali dosing unit (322) for adding alkali, and an oxidation dosing unit (323) for adding oxidant. 323), a phosphorus removal dosing unit (324) for adding phosphorus removal agent, a coagulant dosing unit (325) for adding coagulant aid, and a reduction dosing unit (326) for adding reducing agent. The acid dosing unit (321) and the alkali dosing unit (322) are respectively connected to the pH adjustment tank (311) and the final discharge tank (315). The oxidation dosing unit (323) and the phosphorus removal dosing unit (324) are both connected to the primary chemical reaction tank (312). The coagulant aid dosing unit (325) is connected to the secondary chemical reaction tank (313). The reduction dosing unit (326) is connected between the final discharge tank (315) and the drainage pipe (4). The non-radioactive wastewater treatment system of the nuclear power plant also includes a recirculation pipeline (33), one end of which is connected to the drainage pipeline (4), and the other end of which is connected to the first wastewater collection tank (21), the second wastewater collection tank (22) and the third wastewater collection tank (23) respectively, so as to repeatedly treat unqualified non-radioactive wastewater; The first wastewater collection tank (21), the second wastewater collection tank (22), and the third wastewater collection tank (23) are respectively connected to the pH adjustment tank (311) via the first transfer pump (51); the nuclear power plant non-radioactive wastewater treatment system also includes a bypass pipeline (34), one end of which is connected between the first transfer pump (51) and the pH adjustment tank (311), and the other end of which is connected to the first wastewater collection tank (21), the second wastewater collection tank (22), and the third wastewater collection tank (23) respectively; the bypass pipeline (34) is used for wastewater transfer between each wastewater collection tank to keep at least one wastewater collection tank in an empty state, and the circulating return pipeline (33) is used to return unqualified non-radioactive wastewater to the wastewater collection tank in an empty state.

2. The nuclear power plant non-radioactive wastewater treatment system as described in claim 1, characterized in that, A first automatic valve (61) is provided between the inlet pipe (1) and the first wastewater collection tank (21), a second automatic valve (62) is provided between the inlet pipe (1) and the second wastewater collection tank (22), and a third automatic valve (63) is provided between the inlet pipe (1) and the third wastewater collection tank (23). The nuclear power plant non-radioactive wastewater treatment system also includes a control unit (8). An inlet water quality analyzer (71) is provided on the inlet pipe (1). The inlet water quality analyzer (71) is used to detect the COD, nitrogen content and phosphorus content of the non-radioactive wastewater. The control unit (8) is electrically connected to the inlet water quality analyzer (71), the first automatic valve (61), the second automatic valve (62) and the third automatic valve (63) respectively.

3. The nuclear power plant non-radioactive wastewater treatment system as described in claim 2, characterized in that, The control unit (8) is also electrically connected to the oxidation dosing unit (323) and the phosphorus removal dosing unit (324), respectively. The control unit (8) is used to control the dosing amount of the oxidation dosing unit (323) and the phosphorus removal dosing unit (324) according to the COD, nitrogen content and phosphorus content of the non-discharged wastewater detected by the influent water quality analyzer (71).

4. The nuclear power plant non-radioactive wastewater treatment system as described in claim 1, characterized in that, The drainage pipeline (4) is equipped with a fourth automatic valve (64), and the circulating return pipeline (33) is equipped with a fifth automatic valve (65); the nuclear power plant non-radioactive wastewater treatment system also includes a control unit (8), the drainage pipeline (4) is equipped with a drainage water quality analyzer (72), and the control unit (8) is electrically connected to the drainage water quality analyzer (72), the fourth automatic valve (64) and the fifth automatic valve (65) respectively.

5. The nuclear power plant non-radioactive wastewater treatment system as described in claim 4, characterized in that, The control unit (8) is also electrically connected to the reduction dosing unit (326). The control unit (8) is used to control the dosage of the reduction dosing unit (326) according to the residual chlorine concentration of the non-discharged wastewater detected by the wastewater quality analyzer (72).

6. The nuclear power plant non-radioactive wastewater treatment system as described in claim 1, characterized in that, The first wastewater collection tank (21) is equipped with a first liquid level sensor, the second wastewater collection tank (22) is equipped with a second liquid level sensor, the third wastewater collection tank (23) is equipped with a third liquid level sensor, the circulating return pipeline (33) is equipped with a sixth automatic valve (66) between the first wastewater collection tank (21), the circulating return pipeline (33) is equipped with a seventh automatic valve (67) between the second wastewater collection tank (22), and the circulating return pipeline (33) is equipped with an eighth automatic valve (68) between the third wastewater collection tank (23). The nuclear power plant non-radioactive wastewater treatment system also includes a control unit (8), which is electrically connected to the first liquid level sensor, the second liquid level sensor, the third liquid level sensor, the sixth automatic valve (66), the seventh automatic valve (67), and the eighth automatic valve (68).

7. The nuclear power plant non-radioactive wastewater treatment system as described in claim 1, characterized in that, A first pH meter (73) is installed on the pipeline between the pH adjustment tank (311) and the primary chemical reaction tank (312), and a second pH meter (74) is installed on the final discharge tank (315). The nuclear power plant non-radioactive wastewater treatment system also includes a control unit (8), which is electrically connected to the first pH meter (73), the second pH meter (74), the acid dosing unit (321), and the alkali dosing unit (322), respectively. The control unit (8) is used to control the dosage of the acid dosing unit (321) and the alkali dosing unit (322) according to the pH value measured by the first pH meter (73) and the second pH meter (74).

8. The nuclear power plant non-radioactive wastewater treatment system as described in any one of claims 1-7, characterized in that, The number of wastewater treatment units (3) is at least two sets, and at least two sets of wastewater treatment units (3) are arranged in parallel.

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