Method and device system for softening and removing hardness from high-salinity wastewater

Abstract

The application provides a high-salinity wastewater softening and hardness removal method and device system, and the softening and hardness removal method comprises the following steps: injecting wastewater into a reaction unit through a water inlet pipeline, and adding reagents into the reaction unit to purify the wastewater; obtaining the pH value and / or conductivity of the wastewater inlet, the wastewater outlet and the wastewater in the reaction unit; judging whether the water quality of the outlet water reaches a target water quality, and if not, adjusting the reagent adding frequency of adding reagents into the reaction unit according to the pH value and / or conductivity of the wastewater inlet and the wastewater in the reaction unit. Through accurate reagent adding control, the application realizes efficient and convenient softening and hardness removal of high-salinity wastewater.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-salinity wastewater treatment and relates to a method and device system for softening and removing hardness from high-salinity wastewater. BACKGROUND

[0002] In the development process of oil and gas fields, especially in the development process of unconventional shale oil and gas, a large amount of drilling mud filtrate and fracturing flowback fluid is generated. The drilling mud filtrate and fracturing flowback fluid are complex in composition and are intermittently discharged with large fluctuations. After being collected, the drilling mud filtrate and fracturing flowback fluid are usually transported by pipelines or vehicles to a centralized waste disposal plant for unified disposal.

[0003] The drilling mud filtrate and fracturing flowback fluid are associated water generated along with drilling, including formation water and water injected during the fracturing process, and have the characteristics of high COD (Chemical Oxygen Demand) concentration (3000-8000 mg / L), high total dissolved solids concentration (20000-80000 us / cm), and high hardness (3000-20000 mg / L). The drilling mud filtrate and fracturing flowback fluid are typical high-salinity, high-hardness, and high-COD wastewater, and are extremely difficult to treat.

[0004] At present, the traditional treatment process for drilling mud filtrate and fracturing flowback fluid includes oil removal treatment, hardness removal treatment, COD removal treatment, and membrane treatment. The existing hardness removal treatment is mainly adjusted and controlled by the following two methods: (1) the calcium and magnesium contents are tested at all times, and the required amount of chemicals is calculated and adjusted according to the following chemical equation; and (2) the amount of chemicals is directly determined and adjusted through on-site beaker experiments.

[0005] Mg 2+ + Ca(OH)2→ Mg(OH)2↓ + Ca 2+ ;

[0006] Ca 2+ + Na2CO3→ CaCO3↓ + 2Na + .

[0007] However, it is difficult to control and adjust the hardness removal of drilling mud filtrate and fracturing flowback fluid by using the above two methods. The main reason is that the types of wastewater are different during the actual collection of wastewater, and effective homogenization cannot be achieved. The existing technology has a lag, which will lead to the collapse of the hardness removal system and even the entire system cannot operate normally.

[0008] Therefore, how to quickly and effectively control the dosing during the hardness removal process of high-salinity and high-hardness wastewater to improve the softening and hardness removal effect is a technical problem that needs to be solved by the technical personnel in the field. SUMMARY

[0009] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-salinity wastewater softening and hardness removal method and device system, which realizes efficient and convenient softening and hardness removal of high-salinity wastewater through precise dosing control.

[0010] To achieve this purpose, the present application adopts the following technical solutions:

[0011] In the first aspect, the present application provides a high-salinity wastewater softening and hardness removal method, which comprises:

[0012] The wastewater is injected into the reaction unit through the water inlet pipeline, and a reagent is added into the reaction unit for purification treatment of the wastewater.

[0013] The pH value and / or conductivity of the wastewater inlet, wastewater outlet and wastewater in the reaction unit are obtained.

[0014] It is determined whether the outlet water quality reaches the target water quality, and if not, the dosing frequency of the reagent added into the reaction unit is adjusted according to the pH value and / or conductivity of the wastewater inlet and wastewater in the reaction unit.

[0015] As a preferred technical solution of the present application, the softening and hardness removal method comprises the following steps:

[0016] S1: The wastewater is sequentially sent into the magnesium removal device, calcium removal device and flocculation device through the water inlet pipeline, and a hardness removal reagent is added into the magnesium removal device, a softening reagent is added into the calcium removal device, and a flocculation reagent is added into the flocculation device.

[0017] S2: The first pH value of the wastewater inlet and the second pH value of the wastewater in the magnesium removal device are obtained, the first pH value is used to monitor the change of the inlet water quality in real time, an acid-base threshold value is set, the second pH value is compared with the acid-base threshold value, and the dosing frequency of the hardness removal reagent is adjusted according to the analysis result.

[0018] S3: The first conductivity of the wastewater inlet and the second conductivity of the wastewater in the flocculation device are obtained, and a collection time is set, the effluent hardness of the wastewater is detected every interval of the collection time.

[0019] S4: It is determined whether the outlet water quality of the wastewater exceeds the target hardness range, if yes, the dosing frequency of the softening reagent is increased, otherwise, it is determined whether the difference between the first conductivity and the second conductivity is greater than a purification threshold value.

[0020] When the difference is greater than the purification threshold value, the dosing frequency of the softening reagent is reduced, and when the difference is less than or equal to the purification threshold value, the dosing frequency of the softening reagent remains unchanged.

[0021] As a preferred technical solution of the present application, the method for softening and removing hardness of high-salinity wastewater further comprises: obtaining a third pH value of the wastewater in the calcium removal device, and monitoring the dosing of the softening agent in real time through the third pH value.

[0022] The hardness removal agent comprises lime or liquid caustic soda.

[0023] The softening agent is sodium carbonate.

[0024] The flocculation agent comprises any one or a combination of at least two of polyacrylamide, polyferric sulfate, and polyaluminum chloride.

[0025] As a preferred technical solution of the present application, the acid-base threshold value is 11-11.7, for example, it can be 11, 11.1, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6 or 11.7, but is not limited to the listed values, other values not listed in this range are also applicable.

[0026] The collection time is 30-60 min, for example, it can be 30 min, 32 min, 35 min, 38 min, 40 min, 45 min, 48 min, 50 min, 53 min, 55 min, 58 min or 60 min, but is not limited to the listed values, other values not listed in this range are also applicable.

[0027] The target hardness range is 0-300 mg / L, for example, it can be 0 mg / L, 50 mg / L, 80 mg / L, 100 mg / L, 120 mg / L, 140 mg / L, 150 mg / L, 160 mg / L, 180 mg / L, 200 mg / L, 220 mg / L, 250 mg / L, 280 mg / L or 300 mg / L, but is not limited to the listed values, other values not listed in this range are also applicable.

[0028] The purification threshold is 1800-2000 us / cm, for example, it can be 1800 us / cm, 1820 us / cm, 1840 us / cm, 1850 us / cm, 1860 us / cm, 1880 us / cm, 1900 us / cm, 1920 us / cm, 1950 us / cm, 1960 us / cm, 1980 us / cm or 2000 us / cm, but is not limited to the listed values, other values not listed in this range are also applicable.

[0029] As a preferred technical solution of the present application, the method for softening and removing hardness of high-salinity wastewater further comprises:

[0030] The wastewater discharged by the flocculation device is sequentially sent to the maturation device, the precipitation device, the neutralization device and the buffer device, and a neutralizing agent is added to the neutralization device.

[0031] The fourth pH value of the wastewater in the buffer device is obtained, and it is determined whether the fourth pH value is out of the target pH range, and then the amount of the neutralizing agent is adjusted.

[0032] The neutralizing agent includes any one of hydrochloric acid, hydrochloric acid or sulfuric acid, or a combination of at least two of them.

[0033] The target pH range of the wastewater in the buffer device is 6-7, for example, it can be 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9 or 7, but not limited to the listed values, other unlisted values in this range are also applicable.

[0034] In a second aspect, the present application provides a high-salinity wastewater softening and hardness removal device system, which is used for the softening and hardness removal method of the first aspect, and comprises a reaction unit, a dosing unit and a central control unit; the reaction unit comprises a water inlet pipeline, a precipitation reactor and a water outlet pipeline connected in sequence; the water inlet pipeline is provided with a first detection module, the precipitation reactor comprises a plurality of purification units, each purification unit is provided with a second detection module, and the water outlet pipeline is provided with a third detection module; the first detection module, the second detection module and the third detection module are used for detecting the quality of the wastewater; the dosing unit is used for providing reagents to the purification units; and the central control unit is electrically connected to the first detection module, the second detection module, the third detection module and the dosing unit.

[0035] As a preferred technical solution of the present application, the first detection module comprises a first pH detection component and a first conductivity detection component arranged on the water inlet pipeline, which are respectively used for detecting the pH value and the conductivity of the wastewater inlet.

[0036] The first pH detection component and the first conductivity detection component are independently electrically connected to the central control unit, and are used for transmitting the pH value and the conductivity of the wastewater inlet to the central control unit.

[0037] As a preferred technical solution of the present application, the plurality of purification units comprise a magnesium removal device, a calcium removal device and a flocculation device connected in sequence.

[0038] The dosing unit comprises a first dosing device, a second dosing device and a third dosing device, the first dosing device is connected to the magnesium removal device, the second dosing device is connected to the calcium removal device, and the third dosing device is connected to the flocculation device; the first dosing device, the second dosing device and the third dosing device each independently comprise a dosing pump and a reagent source.

[0039] The dosing pumps of the first dosing device and the second dosing device are variable frequency dosing pumps, and the variable frequency dosing pumps are electrically connected to the central control unit.

[0040] The second detection module comprises a second pH detection component, a third pH detection component and a second conductivity detection component; the second pH detection component is connected to the magnesium removal device, the third pH detection component is connected to the calcium removal device, and the second conductivity detection component is connected to the flocculation device; and the second pH detection component, the third pH detection component and the second conductivity detection component are independently electrically connected to the central control unit.

[0041] Preferably, the outlet end of the second dosing device is further provided with a flow detection component, and the flow detection component is electrically connected to the central control unit.

[0042] Preferably, a first stirring assembly is arranged in the magnesium removal device, a second stirring assembly is arranged in the calcium removal device, and a third stirring assembly is arranged in the flocculation device.

[0043] As a preferred technical solution of the present application, the plurality of purification units further comprise a curing device, a precipitation device, a neutralization device and a buffer device connected in sequence, the water inlet end of the curing device is connected to the flocculation device, and the water outlet end of the buffer device is connected to the water outlet pipeline.

[0044] The dosing unit further comprises a fourth dosing device, the fourth dosing device is connected to the neutralization device, and the fourth dosing device comprises a dosing pump and a medicament source, and the dosing pump is electrically connected to the central control unit.

[0045] The second detection module further comprises a fourth pH detection component connected to the buffer device, and the fourth pH detection component is electrically connected to the central control unit.

[0046] Preferably, a fourth stirring assembly is arranged in the neutralization device.

[0047] As a preferred technical solution of the present application, the third detection module comprises a hardness detection component arranged on the water outlet pipeline, for detecting the water hardness of the wastewater outlet.

[0048] The numerical range of the present application includes not only the above-mentioned point values, but also any point values between the above-mentioned numerical ranges which are not mentioned, and due to the limited space and for the sake of simplicity, the present application does not enumerate the specific point values included in the range.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] The application provides a high-salinity wastewater softening and hardness removal method and device system, which is based on the accurate adjustment of dosing frequency according to the water quality and the hardness of the effluent, guarantees the efficient and stable operation of the system, meets the softening and hardness removal requirements of the high-salinity wastewater, and has the advantages of simple process, low cost, simple equipment maintenance, environmental friendliness, good economic benefits and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 A structure schematic view of the high-salinity wastewater softening and hardness removal device system provided for the embodiment 1 of the application.

[0052] 1 - inlet pipeline; 101 - first pH detection component; 102 - first conductivity detection component; 2 - magnesium removal reaction tank; 201 - second pH detection component; 202 - first stirring assembly; 3 - calcium removal reaction tank; 301 - third pH detection component; 302 - second stirring assembly; 4 - flocculation tank; 401 - second conductivity detection component; 402 - third stirring assembly; 5 - maturation tank; 6 - sedimentation tank; 7 - neutralization reaction tank; 701 - fourth stirring assembly; 8 - buffer tank; 801 - fourth pH detection component; 9 - outlet pipeline; 901 - hardness detection component; 10 - first dosing device; 11 - second dosing device; 111 - flow detection component; 12 - third dosing device; 13 - fourth dosing device. DETAILED DESCRIPTION

[0053] It should be understood that, in the description of the application, the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms "first", "second", and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", and the like can explicitly or implicitly include one or more of the features. In the description of the application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0054] It should be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "arrangement", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0055] It should be understood by those skilled in the art that the present application necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing the process integrity, but the above content is not the main point of the present application, and those skilled in the art can add layout according to the process flow and equipment structure selection, and the present application does not make special requirements and specific limitations.

[0056] The technical solutions of the present application will be further illustrated by specific embodiments in conjunction with the accompanying drawings.

[0057] In one embodiment, the present application provides a method for softening and removing hardness of high-salinity wastewater, comprising:

[0058] The wastewater is injected into the reaction unit through the water inlet pipeline, and reagents are added into the reaction unit for purification treatment of the wastewater;

[0059] The pH value and / or conductivity of the wastewater inlet, wastewater outlet and wastewater in the reaction unit are obtained;

[0060] It is judged whether the water quality of the outlet water reaches the target water quality, if not, the dosing frequency of adding reagents into the reaction unit is adjusted according to the pH value and / or conductivity of the wastewater inlet and wastewater in the reaction unit.

[0061] The high-salinity wastewater in the present application refers to wastewater with COD concentration of 3000-8000 mg / L, total dissolved solids concentration of 20000-80000 us / cm, and hardness of 3000-20000 mg / L, which is difficult to treat. For the above wastewater, the present application realizes efficient and convenient wastewater softening and hardness removal through precise dosing control.

[0062] Specifically, the softening and hardness removal method comprises the following steps:

[0063] S1: The wastewater is sequentially sent into the magnesium removal device, calcium removal device and flocculation device through the water inlet pipeline, and the hardness removal reagent is added into the magnesium removal device, the softening reagent is added into the calcium removal device, and the flocculation reagent is added into the flocculation device;

[0064] S2: obtaining a first pH value of wastewater influent and a second pH value of wastewater in the magnesium removal device, monitoring the influent water quality in real time through the first pH value, setting an acid-base threshold value, analyzing and comparing the second pH value with the acid-base threshold value, and adjusting the dosing frequency of the hardness removal agent according to the analysis result;

[0065] S3: obtaining a first conductivity of wastewater influent and a second conductivity of wastewater in the flocculation device, and setting a collection time; detecting the effluent hardness of wastewater every interval of the collection time;

[0066] S4: judging whether the effluent water quality exceeds the target hardness range, if yes, adjusting to increase the dosing frequency of the softening agent, otherwise, judging whether the difference between the first conductivity and the second conductivity is greater than a purification threshold value;

[0067] When the difference is greater than the purification threshold value, the dosing frequency of the softening agent is adjusted to be reduced; when the difference is less than or equal to the purification threshold value, the dosing frequency of the softening agent remains unchanged.

[0068] Further, the high-salinity wastewater softening and hardness removal method further comprises: obtaining a third pH value of wastewater in the calcium removal device, and monitoring the dosing of the softening agent in real time through the third pH value. That is, according to the change of the third pH value, the water quality of wastewater in the calcium removal device is monitored, and the amount and start-stop of dosing are controlled.

[0069] Specifically, the hardness removal agent comprises lime or liquid caustic soda. The softening agent is sodium carbonate. The flocculation agent comprises any one or a combination of at least two of polyacrylamide, polyferric sulfate or polyaluminum chloride.

[0070] In some embodiments, the acid-base threshold value is 11-11.7. The collection time is 30-60 min. The target hardness range is 0-300 mg / L. The purification threshold value is 1800-2000 us / cm.

[0071] In some embodiments, the high-salinity wastewater softening and hardness removal method further comprises:

[0072] The wastewater discharged from the flocculation device is sequentially sent into a maturation device, a precipitation device, a neutralization device and a buffer device for effluent, and a neutralizing agent is added into the neutralization device;

[0073] Obtaining a fourth pH value of wastewater in the buffer device, judging whether the fourth pH value exceeds a target pH range, and further adjusting the dosing amount of the neutralizing agent.

[0074] The target pH range of the wastewater in the buffering device is 6-7, and when the fourth pH value exceeds the above range, the amount of neutralizing agent provided to the neutralizing device can be adjusted. Further, the amount of the neutralizing agent can be adjusted by adjusting the start-stop or opening degree of the dosing pump for dosing. Specifically, the neutralizing agent includes hydrochloric acid, hydrochloric acid, or a combination of at least two of sulfuric acid.

[0075] In another specific embodiment, the present application provides a high-salinity wastewater softening and hardness removal device system for the softening and hardness removal method described in a specific embodiment. The device system includes a reaction unit, a dosing unit, and a central control unit. The reaction unit includes a water inlet pipeline, a sedimentation reactor, and a water outlet pipeline connected in sequence. The water inlet pipeline is provided with a first detection module, the sedimentation reactor includes a plurality of purification units, the purification units are provided with a second detection module, and the water outlet pipeline is provided with a third detection module. The first detection module, the second detection module, and the third detection module are used to detect the quality of the wastewater; the dosing unit is used to provide reagents to the purification units. The central control unit is electrically connected to the first detection module, the second detection module, the third detection module, and the dosing unit. The first detection module obtains the quality of the wastewater inlet water and transmits it to the central control unit; the second detection module obtains the quality of the wastewater in the purification units and transmits it to the central control unit; the third detection module obtains the quality of the wastewater outlet water and transmits it to the central control unit; and the central control unit analyzes the quality of the outlet water, the quality of the inlet water, and the quality of the wastewater in the purification units to feedback control the dosing of the dosing unit.

[0076] The central control unit of the present application is a terminal for operation and online detection of the reaction unit and the dosing unit, which can include a master control device, and necessary connection wires for connecting each reaction unit, dosing unit, first detection module, second detection module, and third detection module, etc. to establish a complete communication network. The master control device can remotely control the reaction unit and the dosing unit through software and hardware and electromechanical control technology familiar to those skilled in the art. In order to facilitate the staff to master the system operation, the master control device can also be provided with a display and an operation interface, etc., which are not specially limited by the present application, and the skilled person in the art needs to reasonably adjust, add or delete according to the actual production needs.

[0077] In some embodiments, the first detection module includes a first pH detection component and a first conductivity detection component arranged on the water inlet pipeline, respectively used to detect the pH value and the conductivity of the wastewater inlet water. The first pH detection component and the first conductivity detection component are independently electrically connected to the central control unit for transmitting the pH value and the conductivity of the wastewater inlet water to the central control unit.

[0078] In some embodiments, the several purification units include a magnesium removal device, a calcium removal device and a flocculation device connected in sequence. In the application, wastewater flows into the magnesium removal device through the inlet pipe, and reacts with the added reagent to form a precipitate, thereby removing magnesium ions in the wastewater; the wastewater flowing into the calcium removal device reacts with the added reagent to form a precipitate, thereby removing calcium ions in the wastewater; and the wastewater in the flocculation device interacts with the added reagent to cause the aggregation and removal of colloids, precipitates and small suspended solids in the wastewater. The structure and size of the magnesium removal device, the calcium removal device and the flocculation device are not specially required in the application, and wastewater treatment devices commonly used in the art can be used, and the size of the treatment device can be adjusted according to the wastewater treatment capacity. In order to improve the wastewater treatment effect, the reaction unit of the application is also provided with a reflux pipe, one end of which is connected to the outlet pipe, and the other end is connected to the magnesium removal device or the calcium removal device. When it is detected that the water quality of the outlet water does not meet the requirements, the wastewater is refluxed to the magnesium removal device or the calcium removal device through the reflux pipe for further softening and hardening removal until the discharge requirements are met.

[0079] The dosing unit includes a first dosing device, a second dosing device and a third dosing device, the first dosing device is connected to the magnesium removal device, the second dosing device is connected to the calcium removal device, and the third dosing device is connected to the flocculation device; the first dosing device, the second dosing device and the third dosing device each independently include a dosing pump and a reagent source. The dosing pumps of the first dosing device and the second dosing device are variable frequency dosing pumps, and the variable frequency dosing pumps are electrically connected to the central control unit. The first dosing device is used to provide a hard removal reagent to the magnesium removal device, the second dosing device is used to provide a softening reagent to the calcium removal device, and the third dosing device is used to provide a flocculation reagent to the flocculation device. The dosing pumps of the first dosing device, the second dosing device and the third dosing device are used to pump the reagents from the reagent sources into the corresponding purification units. The dosing pump of the third dosing device can be a variable frequency dosing pump or a conventional pump. The adjustment unit of the variable frequency dosing pump is adjusted by the person skilled in the art according to the actual operation, preferably controlled and adjusted at 3Hz or 5Hz as an adjustment unit, to realize full-automatic operation. Furthermore, the above-mentioned dosing device also includes necessary connecting pipelines and on-off control valves, which are not specially limited in the application, and the person skilled in the art needs to reasonably adjust, add or delete according to the actual production needs, and it needs to be clear that the new technical solutions generated by deleting part of the non-essential connecting pipelines and on-off control valves, or replacing single-function on-off control valves with multi-function integrated control valves and other conventional technical means commonly used and known by the person skilled in the art also fall within the disclosure range and protection range of the application.

[0080] The second detection module comprises a second pH detection component, a third pH detection component and a second conductivity detection component; the second pH detection component is connected to the magnesium removal device, the third pH detection component is connected to the calcium removal device, and the second conductivity detection component is connected to the flocculation device; the second pH detection component, the third pH detection component and the second conductivity detection component are independently electrically connected to the central control unit.

[0081] Further, the outlet end of the second dosing device is further provided with a flow detection component which is electrically connected to the central control unit and is used for monitoring whether the dosing flow is normal. The type of the flow detection component is not specially limited in the present application and can be an electromagnetic flowmeter or other forms of flowmeters.

[0082] Preferably, a first stirring assembly is arranged in the magnesium removal device, a second stirring assembly is arranged in the calcium removal device, and a third stirring assembly is arranged in the flocculation device. In the operation of the present application, the wastewater is stirred to make the wastewater and the added reagents fully mix and react, thereby improving the treatment effect.

[0083] In some embodiments, the several purification units further comprise, in sequence, a maturation device, a precipitation device, a neutralization device and a buffer device; the water inlet end of the maturation device is connected to the flocculation device, and the water outlet end of the buffer device is connected to the water outlet pipeline. In the present application, the wastewater discharged from the flocculation device enters the maturation device and then flows into the precipitation device, so that the pollutants such as precipitates, colloids and suspended solids in the wastewater are removed, the sewage sludge is discharged from the bottom of the precipitation device, and the purified water enters the neutralization device for further neutralization treatment. The wastewater flowing into the neutralization device reacts with the added reagents to neutralize the acid-base of the wastewater, and then enters the buffer device. When the water quality of the wastewater meets the treatment requirements, the wastewater flows out through the water outlet pipeline. The structure and size of the maturation device, the precipitation device, the neutralization device and the buffer device are not specially required in the present application, and the wastewater treatment devices commonly used in the art can be used, and the size of the treatment device can be adjusted according to the wastewater treatment capacity. The dosing unit further comprises a fourth dosing device which is connected to the neutralization device; the fourth dosing device comprises a dosing pump and a reagent source; the dosing pump is electrically connected to the central control unit. The dosing pump can be a variable frequency pump or a conventional pump, and its on-off and opening degree can be remotely controlled by the central control unit. The second detection module further comprises a fourth pH detection component connected to the buffer device; the fourth pH detection component is electrically connected to the central control unit and is used for detecting the water quality of the wastewater in the buffer device, thereby adjusting the dosing amount in the neutralization device. Preferably, a fourth stirring assembly is arranged in the neutralization device.

[0084] Further, in order to improve the wastewater softening effect, the dosing unit further comprises a fifth dosing device connected to the calcium removal device for providing a water purifying agent to the calcium removal device. The water purifying agent comprises any one or a combination of at least two of polyacrylamide, polyferric sulfate or polyaluminum chloride commonly used in the art.

[0085] In some embodiments, the third detection module comprises a hardness detection component arranged on the water outlet pipeline for detecting the hardness of the wastewater effluent. During the operation of the present application, the hardness of the wastewater effluent in the water outlet pipeline is detected at intervals. When the hardness of the wastewater effluent meets the requirements, the wastewater effluent can be discharged from the system. When the hardness of the wastewater effluent cannot meet the requirements, the dosing in the sedimentation reactor is adjusted by feedback control of the central control unit.

[0086] In some embodiments, the sedimentation reactor comprises a inclined tube reactor, a high-density reactor or a vertical flow reactor. The present application does not make specific limitations on the arrangement of the purification units in the sedimentation reactor, and the skilled person in the art can make reasonable adjustments according to the actual production needs.

[0087] The present application exemplarily provides the following specific structure of the sedimentation reactor: the sedimentation reactor is composed of a magnesium removal reaction pool, a calcium removal reaction pool, a flocculation pool, a maturation pool, a sedimentation pool, a neutralization reaction pool and a buffer pool which are sequentially connected and supported and fixed by a rack. The bottom of the magnesium removal reaction pool is provided with a first water outlet which is connected to the middle part of the calcium removal reaction pool; the upper part of the calcium removal reaction pool is provided with a first overflow port which is connected to the upper part of the flocculation pool; the bottom of the flocculation pool is provided with a second water outlet which is connected to the bottom of the maturation pool; the upper part of the maturation pool is provided with a second overflow port which is connected to the sedimentation pool; the bottom of the sedimentation pool is provided with at least two sludge discharge hoppers for discharging sludge; the upper part of the sedimentation pool is provided with a water discharge assembly which is connected to the neutralization reaction pool for discharging the purified water into the neutralization reaction pool; the bottom of the neutralization reaction pool is provided with a third water outlet which is connected to the buffer pool, and the bottom of the buffer pool is connected to the water outlet pipeline. In order to further improve the purification effect, a plurality of baffle plates can be arranged in the sedimentation pool to prolong the residence time of the wastewater. It should be noted that the above description of the structure of each purification unit does not constitute a further limitation on the protection scope of the present application, i.e., each purification unit disclosed in the prior art or not disclosed in the new technology can be used in the present application, and is not limited to the operation module with the above structure. As long as the purification unit can achieve the same or similar function, it can be replaced arbitrarily, and the technical solution obtained after the replacement also falls within the protection scope and disclosure range of the present application.

[0088] Example 1

[0089] The embodiment provides a high-salinity wastewater softening and hardness removal device system, which comprises a reaction unit, a dosing unit and a central control unit. Figure 1 As shown in the figure, the water inlet pipeline 1 is provided with a first pH detection component 101 and a first conductivity detection component 102, which are respectively used for detecting the pH value and conductivity of the wastewater inlet, and the first pH detection component 101 and the first conductivity detection component 102 are independently electrically connected to the central control unit, and are used for transmitting the pH value and conductivity of the wastewater inlet to the central control unit. The water outlet pipeline 9 is provided with a hardness detection component 901 and is electrically connected to the central control unit, and is used for detecting the outlet hardness of the wastewater outlet.

[0090] The sedimentation reactor is composed of a magnesium removal reaction tank 2, a calcium removal reaction tank 3, a flocculation tank 4, a maturation tank 5, a sedimentation tank 6, a neutralization reaction tank 7 and a buffer tank 8 which are sequentially communicated. The bottom of the magnesium removal reaction tank 2 is provided with a first water outlet, which is communicated with the middle part of the calcium removal reaction tank 3; the upper part of the calcium removal reaction tank 3 is provided with a first overflow port, which is communicated with the upper part of the flocculation tank 4; the bottom of the flocculation tank 4 is provided with a second water outlet, which is communicated with the bottom of the maturation tank 5; the upper part of the maturation tank 5 is provided with a second overflow port, which is communicated with the sedimentation tank 6; the bottom of the sedimentation tank 6 is provided with three sludge discharge hoppers for discharging sludge; the upper part of the sedimentation tank 6 is provided with a water discharge assembly, which is communicated with the neutralization reaction tank 7, and is used for discharging the purified water into the neutralization reaction tank 7; the bottom of the neutralization reaction tank 7 is provided with a third water outlet, which is communicated with the buffer tank 8, and the bottom of the buffer tank 8 is connected to the water outlet pipeline 9. The magnesium removal reaction tank 2 is connected with a second pH detection component 201, the calcium removal reaction tank 3 is connected with a third pH detection component 301, the buffer tank 8 is connected with a fourth pH detection component 801, and the flocculation tank 4 is connected with a second conductivity detection component 401. The second pH detection component 201, the third pH detection component 301, the second conductivity detection component 401 and the fourth pH detection component 801 are independently electrically connected to the central control unit. The magnesium removal reaction tank 2 is provided with a first stirring assembly 202, the calcium removal device is provided with a second stirring assembly 302, the flocculation tank 4 is provided with a third stirring assembly 402, and the neutralization reaction tank 7 is provided with a fourth stirring assembly 701.

[0091] The dosing unit comprises a first dosing device 10, a second dosing device 11, a third dosing device 12 and a fourth dosing device 13. The first dosing device 10 is connected to the magnesium removal reaction tank 2 for providing lime to the magnesium removal reaction tank 2. The second dosing device 11 is connected to the calcium removal reaction tank 3 for providing sodium carbonate to the calcium removal reaction tank 3, and the outlet end of the second dosing device 11 is further provided with a flow detection component 111 electrically connected to the central control unit. The third dosing device 12 is connected to the flocculation tank 4 for providing polyacrylamide to the flocculation tank 4. The fourth dosing device 13 is connected to the neutralization reaction tank 7 for providing hydrochloric acid to the neutralization reaction tank 7. The first dosing device 10, the second dosing device 11, the third dosing device 12 and the fourth dosing device 13 each independently comprise a dosing pump and a medicament source. The dosing pumps of the first dosing device 10 and the second dosing device 11 are variable frequency dosing pumps, and the dosing pumps of the third dosing device 12 and the fourth dosing device 13 are conventional pumps.

[0092] The method for wastewater softening and hardness removal by using the high-salinity wastewater softening and hardness removal device system provided in the embodiment comprises the following steps:

[0093] (1) Inject wastewater from the wastewater inlet pipeline 1, and sequentially pass through the magnesium removal reaction tank 2, the calcium removal reaction tank 3, the flocculation tank 4, the maturation tank 5, the sedimentation tank 6, the neutralization reaction tank 7 and the buffer tank 8. The dosing unit is used to add lime into the magnesium removal reaction tank 2, add sodium carbonate into the calcium removal reaction tank 3, add polyaluminum chloride into the flocculation tank 4, and add hydrochloric acid into the neutralization reaction tank 7;

[0094] (2) Obtain a first pH value of the wastewater inlet and a second pH value of the wastewater in the magnesium removal reaction tank 2. Real-time monitor the change of the wastewater quality by the first pH value, set an acid-base threshold value, analyze and compare the second pH value and the acid-base threshold value, and adjust the dosing frequency of the hardness removal medicament according to the analysis result;

[0095] (3) Obtain a first electric conductivity of the wastewater inlet by using the first electric conductivity detection component 102, and obtain a second electric conductivity of the wastewater in the flocculation tank 4 by using the second electric conductivity detection component 401. Every 1 h, detect the outlet water hardness of the wastewater outlet pipeline 9;

[0096] (4) Judge whether the outlet water hardness exceeds 200 mg / L. If yes, adjust to increase the dosing frequency of the softening medicament, otherwise, judge whether the difference between the first electric conductivity and the second electric conductivity is greater than 2000 us / cm;

[0097] When the difference is greater than 2000 us / cm, adjust to decrease the dosing frequency of the softening medicament, and when the difference is less than or equal to a purification threshold value, the dosing frequency of the softening medicament remains unchanged;

[0098] (5) the third pH value of the wastewater in the calcium removal reaction tank 3 is obtained, the wastewater quality in the calcium removal reaction tank 3 is monitored based on the change of the third pH value, and the dosing amount and the dosing start-stop are controlled;

[0099] (6) the fourth pH value of the wastewater in the buffer tank 8 is obtained, whether the fourth pH value is 6-7 is judged, and when the fourth pH value is out of the range of 6-7, the dosing amount of the hydrochloric acid provided to the neutralization reaction tank 7 is adjusted.

[0100] Embodiment 2

[0101] The embodiment provides a high-salinity wastewater softening and hardness removal device system, and the difference from the embodiment 1 is that the dosing unit further comprises a fifth dosing device connected with the calcium removal reaction tank, which is used for providing polyaluminum chloride to the softening reaction tank, and the rest of the structure is the same as that of the embodiment 1.

[0102] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for softening and removing hardness from high-salinity wastewater, characterized in that, The softening and hardening method includes the following steps: S1: Wastewater is sequentially fed into the magnesium removal device, calcium removal device and flocculation device through the inlet pipe. Hardening agent is added to the magnesium removal device, softening agent is added to the calcium removal device and flocculant is added to the flocculation device. S2: Obtain the first pH value of the wastewater inlet and the second pH value of the wastewater in the magnesium removal device. Monitor the changes in the inlet water quality in real time through the first pH value, set acid and alkali thresholds, analyze and compare the second pH value with the acid and alkali thresholds, and adjust the dosing frequency of the hardening agent based on the analysis results. S3: Obtain the first conductivity of the wastewater inlet and the second conductivity of the wastewater in the flocculation device, and set the collection time. At each collection time interval, detect the hardness of the wastewater effluent. S4: Determine whether the wastewater effluent quality exceeds the target hardness range. If so, adjust and increase the dosing frequency of the softening agent. Otherwise, determine whether the difference between the first conductivity and the second conductivity is greater than the purification threshold. When the difference is greater than the purification threshold, the frequency of adding the softening agent is adjusted to decrease; when the difference is less than or equal to the purification threshold, the frequency of adding the softening agent remains unchanged. The softening and hardening method further includes: obtaining the third pH value of the wastewater in the calcium removal device, and monitoring the dosing of softening agent in real time based on the third pH value; The hardening agent includes lime or liquid alkali; the softening agent is sodium carbonate; the flocculant includes any one or a combination of at least two of polyacrylamide, polyferric sulfate, or polyaluminum chloride.

2. The softening and hardening method according to claim 1, characterized in that, The acid-base threshold is 11~11.7; The data collection time is 30-60 minutes; The target hardness range is 0~300mg / L; The purification threshold is 1800~2000 μS / cm.

3. The softening and hardening method according to claim 1 or 2, characterized in that, The method for softening and removing hardness from high-salinity wastewater also includes: The wastewater discharged from the flocculation device is sequentially sent to the maturation device, sedimentation device, neutralization device and buffer device for effluent discharge, and neutralizing agent is added to the neutralization device. Obtain the fourth pH value of the wastewater in the buffer device, determine whether the fourth pH value exceeds the target pH range, and then adjust the dosage of the neutralizing agent. The neutralizing agent includes hydrochloric acid or sulfuric acid; The target pH range for the wastewater in the buffer device is 6-7.

4. A system for softening and removing hardness from high-salinity wastewater, characterized in that, The high-salinity wastewater softening and hardening device system is used in the softening and hardening method according to any one of claims 1-3. The device system includes a reaction unit, a dosing unit, and a central control unit. The reaction unit includes an inlet pipe, a sedimentation reactor, and an outlet pipe connected in sequence. A first detection module is installed on the inlet pipe. The sedimentation reactor includes several purification units, each purification unit is equipped with a second detection module, and the outlet pipe is equipped with a third detection module. The first, second, and third detection modules are used to detect the wastewater quality. The dosing unit is used to provide reagents to the purification units. The central control unit is electrically connected to the first detection module, the second detection module, the third detection module, and the dosing unit.

5. The high-salinity wastewater softening and hardening removal device system according to claim 4, characterized in that, The first detection module includes a first pH detection component and a first conductivity detection component installed on the inlet pipe, which are used to detect the pH value and conductivity of the wastewater inlet, respectively. The first pH detection component and the first conductivity detection component are independently and electrically connected to the central control unit, and are used to transmit the acidity and alkalinity of the wastewater influent to the central control unit.

6. The high-salinity wastewater softening and hardening device system according to claim 5, characterized in that, The plurality of purification units include a magnesium removal device, a calcium removal device and a flocculation device connected in sequence; The dosing unit includes a first dosing device, a second dosing device, and a third dosing device. The first dosing device is connected to the magnesium removal device, the second dosing device is connected to the calcium removal device, and the third dosing device is connected to the flocculation device. The first dosing device, the second dosing device, and the third dosing device each independently include a dosing pump and a reagent source. Both the first and second dosing devices use variable frequency dosing pumps, which are electrically connected to the central control unit. The second detection module includes a second pH detection component, a third pH detection component, and a second conductivity detection component; the second pH detection component is connected to the magnesium removal device, the third pH detection component is connected to the calcium removal device, and the second conductivity detection component is connected to the flocculation device; the second pH detection component, the third pH detection component, and the second conductivity detection component are independently electrically connected to the central control unit.

7. The high-salinity wastewater softening and hardening device system according to claim 6, characterized in that, The outlet end of the second dosing device is also equipped with a flow detection component, which is electrically connected to the central control unit.

8. The high-salinity wastewater softening and hardening device system according to claim 6, characterized in that, The magnesium removal device is equipped with a first stirring component, the calcium removal device is equipped with a second stirring component, and the flocculation device is equipped with a third stirring component.

9. The high-salinity wastewater softening and hardening device system according to claim 8, characterized in that, The plurality of purification units further include a maturation device, a sedimentation device, a neutralization device and a buffer device connected in sequence, wherein the inlet end of the maturation device is connected to the flocculation device and the outlet end of the buffer device is connected to the outlet pipe. The dosing unit further includes a fourth dosing device, which is connected to the neutralization device. The fourth dosing device includes a dosing pump and a reagent source, and the dosing pump is electrically connected to the central control unit. The second detection module further includes a fourth pH detection component connected to the buffer device, the fourth pH detection component being electrically connected to the central control unit.

10. The high-salinity wastewater softening and hardening device system according to claim 9, characterized in that, The neutralization device is equipped with a fourth stirring component.

11. The high-salinity wastewater softening and hardening device system according to claim 4, characterized in that, The third detection module includes a hardness detection component installed on the effluent pipe, used to detect the hardness of the effluent wastewater.

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