A hard removal and purification device for wastewater before membrane concentration

Abstract

The application discloses a hard removal and purification device for wastewater before membrane concentration, comprising an integrated pressure type tank body, a security filter unit, an intermediate water distribution unit, an ion exchange softening unit and a water inlet and water distribution unit arranged in the tank body in sequence from top to bottom; a detachable upper head is arranged at the top of the tank body, a lower head is arranged at the bottom of the tank body, and process interfaces are arranged on the side wall of the tank body corresponding to each unit, so that the whole process functions such as water inlet, water production, backwashing, regeneration, sewage discharge and the like are realized. Compared with the traditional split type scheme, the resin catcher, the softened water tank and the low-pressure water supply pump are omitted, the service life of the filter element is prolonged to one year, the operation and maintenance cost is greatly reduced, the secondary pollution of the intermediate water tank and the secondary pressure boosting energy consumption are avoided, the device is suitable for wastewater zero discharge scenes such as gas circulating power stations and the like, and the stable operation of the subsequent membrane system is ensured.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology for combined cycle gas turbine power plants, and in particular to a hardness removal and purification device for wastewater before membrane concentration. Background Technology

[0002] In the zero-discharge treatment process of wastewater from gas-fired combined cycle power plants, multi-stage membrane concentration (reverse osmosis, electrodialysis) and evaporation crystallization are the core technical pathways. The hardness and suspended solids of the influent directly determine the operating life and stability of the membrane system. For high-hardness wastewater generated by gas-fired combined cycle power plants, if it directly enters the reverse osmosis system, calcium and magnesium ions will form carbonate and sulfate scale on the membrane surface, causing membrane flux decline, increased system pressure differential, and in severe cases, irreversible damage to the membrane element. At the same time, tiny particles leaked from the pretreatment stage and broken resin can also scratch the membrane surface and cause fouling, significantly shortening the service life of the membrane element.

[0003] In traditional treatment methods, the softening bed and security filter are arranged separately: after pretreatment in a high-density tank, wastewater first enters the softening bed (floating / fixed bed) to remove residual hardness through ion exchange. The softened permeate then passes through a resin trap to intercept broken resin, before entering a softened water tank for depressurization. A low-pressure feed pump then pressurizes the water and sends it to the security filter (using disposable filter cartridges). After filtration, the water enters the reverse osmosis high-pressure pump. This method has several drawbacks:

[0004] 1. High footprint and cost: The softening bed, resin trap, softened water tank and security filter are arranged separately, which requires a large total area and high investment in equipment procurement and civil engineering.

[0005] 2. High filter cartridge maintenance costs: Conventional security filters use disposable PP pleated high-flow filter cartridges, which need to be replaced every 15-30 days under wastewater conditions due to excessive pressure difference. The purchase cost and labor replacement cost are high, and the discarded filter cartridges are prone to secondary pollution.

[0006] 3. Energy waste: After the softened bed product water enters the softened water tank, it is depressurized and requires an additional low-pressure feed water pump for secondary pressurization, resulting in wasted pressure energy and increased power consumption of the system.

[0007] 4. Risk of secondary pollution: The softening tank is an open container, which is prone to the growth of microorganisms and the introduction of impurities, causing secondary pollution to the softened water and affecting the water quality of the subsequent membrane system feed water;

[0008] 5. Functional redundancy: The resin trap and the security filter have overlapping functions. It is only used to intercept broken resin, and the filtration accuracy is insufficient, so it cannot fully intercept the tiny particles of the pre-treatment leak.

[0009] To address the aforementioned issues, the industry urgently needs an integrated, low-maintenance, and energy-efficient pretreatment device that can comprehensively optimize land use, cost, and energy consumption while meeting the influent water quality requirements of membrane systems. Summary of the Invention

[0010] The purpose of this invention is to provide a hardness removal and purification device for wastewater before membrane concentration, so as to solve the problems of large footprint, high cost, high energy consumption and complicated operation and maintenance of traditional split softening-filtration solutions. It realizes the integrated integration of softening bed and security filter, and simultaneously completes hardness removal and precision filtration, ensuring the safe and stable operation of subsequent membrane systems.

[0011] To achieve the above objectives, the present invention provides a hardness removal and purification device for wastewater before membrane concentration, comprising a tank body, the tank body including a cover and a matching tank body detachably connected to the cover, the top of the cover being provided with a detachable upper end cap and the bottom of the tank body being provided with a lower end cap; the inside of the tank body is provided with a security filtration unit, an intermediate water distribution unit, a resin softening unit and a water inlet device arranged sequentially from top to bottom.

[0012] The security filter unit includes an upper perforated plate and a detachable foldable backwashable filter element installed below the upper perforated plate. The water outlet, the upper unqualified water discharge port, and the backwash water inlet located at the top of the tank are all connected to the security filter unit. The water outlet is used for the output of the softened water produced by the security filter unit; the upper unqualified water discharge port is used to discharge the unqualified produced water and the forward wash water during the initial start-up; the backwash water inlet is connected to the backwash water inlet valve of the backwash filter element through a pipeline for the entry of backwash water.

[0013] The intermediate water distribution unit includes a softening bed unit water outlet device and an intermediate discharge device arranged in parallel at the top and bottom. The softening bed unit water outlet device includes an intermediate perforated plate and a dual-speed water cap. The intermediate discharge device includes a main branch pipe and a trapezoidal winding wire set on the main branch pipe. The water inlet located at the bottom of the tank is connected to the softening bed unit water outlet device, and the intermediate discharge port located in the middle of the tank is connected to the intermediate discharge device.

[0014] The resin softening unit is filled with resin, and the resin layer adopts a floating bed operation mode, which can process a large amount of water, matching the water processing capacity of the pleated backwashable filter cartridge; the backwash drain port located at the bottom of the tank, the resin inlet located in the middle of the tank, the resin outlet located at the bottom of the tank, and the regenerated liquid inlet located at the bottom of the tank are respectively connected to the resin softening unit.

[0015] The water inlet device includes a lower perforated plate and a dual-speed water cap. The water inlet device is connected to the water inlet located at the bottom of the tank, and the water inlet is used for the wastewater to be treated to enter.

[0016] According to an embodiment of this application, an inlet valve is provided on the connecting pipe between the inlet and the water outlet of the softening bed unit; a product water valve is provided on the connecting pipe between the outlet and the security filter unit; a backwash inlet valve is provided on the connecting pipe between the backwash inlet and the security filter unit; a backwash outlet valve is provided on the connecting pipe between the backwash outlet and the water outlet of the softening bed unit; a regenerated liquid inlet valve is provided on the connecting pipe between the regenerated liquid inlet and the resin layer; an exhaust valve is provided on the connecting pipe between the exhaust port and the upper end cap; a middle exhaust valve is provided on the connecting pipe between the intermediate discharge port and the intermediate discharge device; and a non-conforming water discharge valve is provided on the connecting pipe between the upper non-conforming water discharge port and the security filter unit.

[0017] According to an embodiment of this application, the upper end cap is provided with an exhaust port for filling the equipment with water and venting air during operation.

[0018] According to an embodiment of this application, the tank body is made of carbon steel lined with rubber, and its design pressure is ≤1MPa, which meets the requirements for pressure operation.

[0019] According to an embodiment of this application, the lower end cap is made of carbon steel lined with rubber, and a bottom manhole is provided on the lower end cap for the inspection and maintenance of the bottom water inlet device and water cap.

[0020] According to an embodiment of this application, the upper end cap is a double-flange cantilever detachable structure, which facilitates the inspection and replacement of the internal filter element and perforated plate.

[0021] According to an embodiment of this application, the pleated backwashable filter element is made of PP material and has a filtration accuracy of 5μm.

[0022] According to the embodiments of this application, the water produced by the hardness removal purification device can meet the following indicators: hardness: ≤2mg / L; sludge density index: ≤4; turbidity: ≤0.2NTU.

[0023] According to embodiments of this application, the upper perforated plate, the middle perforated plate, and the lower perforated plate are all made of SS31603 material.

[0024] According to embodiments of this application, the resin is a weak acid cation exchange resin or a sodium ion exchange resin.

[0025] The advantages of the present invention over the prior art are:

[0026] 1. This device adopts an integrated design, significantly saving space: This application combines the traditional softening bed and security filter into a single pressure vessel, achieving a deep integration of hardening removal and filtration functions. This design, while ensuring treatment effectiveness, significantly reduces equipment footprint, lowers operating costs, and improves system energy efficiency.

[0027] 2. This device comprehensively saves on equipment investment: it eliminates the need for resin traps, softening tanks, and reverse osmosis low-pressure feed pumps in traditional processes, reducing equipment procurement costs and investment in supporting pipelines and electrical systems, while also eliminating the risk of secondary pollution from the softening tank.

[0028] 3. This application significantly reduces operation and maintenance costs: The security filter adopts a pleated backwashable filter element, replacing the traditional disposable filter element, with a normal service life of up to 1 year, avoiding the procurement and labor costs of frequent replacements; at the same time, the regenerated acid can dissolve inorganic scale on the surface of the filter element, extending the service life of the filter element. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the structural composition of a hardness removal and purification device for wastewater before membrane concentration, as exemplified by the present invention.

[0030] Figure 2 This is a schematic diagram of the process interface of the tank body and its corresponding valve, which is an example of the present invention.

[0031] The annotations in the attached figures are explained as follows:

[0032] 10. Tank body, 11. Security filter unit, 12. Intermediate water distribution unit, 13. Resin softening unit, 14. Water inlet device, 20. Cover, 111. Upper perforated plate, 112. Folded backwashable filter element, 121. Softening bed unit water outlet device, 122. Intermediate discharge device;

[0033] Interface numbers correspond to: N1. Inlet, N2. Outlet, N3. Backwash inlet, N4. Backwash drain, N5. Regenerated liquid inlet, N6. Vent, N7. Intermediate discharge outlet, N8. Upper unqualified water discharge outlet, N9. Resin inlet, N10. Resin outlet;

[0034] Valve numbers correspond to: V1: Inlet valve, V2: Product water valve, V3: Backwash inlet valve, V4: Backwash discharge valve, V5: Regenerated liquid inlet valve, V6: Exhaust valve, V7: Intermediate drain valve, V8: Unqualified water discharge valve. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] Please see Figure 1 and Figure 2As shown in the figure, this application discloses a hardness removal and purification device for wastewater before membrane concentration. This device integrates a traditional softening bed and a security filter into a single pressure tank 10. From top to bottom, a security filter unit 11, an intermediate water distribution unit 12, a resin softening unit 13, and an inlet water distribution unit are arranged in sequence to simultaneously achieve hardness removal and precision filtration of wastewater. Compared with the traditional split solution, it saves 60% of the space, eliminates the resin trap, softening water tank, and low-pressure feed water pump, extends the service life of the filter element to 1 year, and significantly reduces the operation and maintenance costs. At the same time, it avoids secondary pollution of the intermediate water tank and secondary pressurization energy consumption. It is suitable for zero-discharge wastewater scenarios such as gas-fired power plants, ensuring the stable operation of the subsequent membrane system.

[0037] In this embodiment, a hardness removal and purification device for wastewater before membrane concentration includes a tank body, which includes a cover 20 and a matching tank body 10 detachably connected to the cover 20. The top of the cover 20 is provided with a detachable upper end cap, and the bottom of the tank body 10 is provided with a lower end cap.

[0038] Specifically, the tank body is made of carbon steel lined with rubber, which is resistant to wastewater corrosion and ion exchange resin abrasion. The design pressure is ≤1MPa, which meets the requirements for pressure operation. The lower end is made of carbon steel lined with rubber and is equipped with a bottom manhole for the inspection and maintenance of the bottom water inlet device 14 and water cap. The upper end adopts a double flange cantilever detachable structure, which facilitates the inspection and replacement of the internal filter element and perforated plate. At the same time, an exhaust port is provided for equipment filling and exhaust during operation.

[0039] Specifically, the upper end cap is equipped with an exhaust port N6, which is used for filling the equipment with water and venting air during operation.

[0040] In this embodiment, the tank body 10 is provided with a security filter unit 11, an intermediate water distribution unit 12, a resin softening unit 13, and a water inlet device 14 arranged from top to bottom inside the tank body 10.

[0041] In this embodiment, the security filter unit 11 includes an upper perforated plate 111 and a foldable backwashable filter element 112 that is detachably installed below the upper perforated plate 111. The water outlet N2, the upper unqualified water discharge port N8, and the backwash water inlet N3 located on the upper part of the tank 10 are all connected to the security filter unit 11. The water outlet N2 is used for the output of water produced after softening and filtration by the security filter unit 11. The upper unqualified water discharge port N8 is used for the discharge of unqualified water and forward wash water from the security filter unit 11. The backwash water inlet N3 is used for the inlet of backwash water.

[0042] Specifically, outlet N2 is located at the top of the tank and is connected to the security filter unit 11 for outputting softened and filtered water. Upper unqualified water discharge outlet N8 is also located at the top of the tank and is connected to the security filter unit 11 for discharging unqualified water and forward wash water. Backwash inlet N3 is located at the top of the tank and is connected to the security filter unit 11 for inlet backwash water.

[0043] Specifically, the pleated backwashable filter element 112 is made of PP material and has a filtration accuracy of 5μm.

[0044] Specifically, the upper perforated plate 111 is made of SS31603 material. The backwash filter element can be installed on the upper perforated plate 111 and can be flexibly disassembled and replaced. It is used to intercept small particles and break up resin in the pretreatment leakage, replacing the function of the traditional resin trap, while protecting the subsequent reverse osmosis membrane elements. When the pressure difference exceeds the standard, the backwashable filter element can restore the filtration performance by backwashing. The normal service life can reach 1 year, which greatly reduces the operation and maintenance costs.

[0045] In this embodiment, the intermediate water distribution unit 12 includes a softening bed unit water outlet device 121 and an intermediate discharge device 122 arranged in parallel. The softening bed unit water outlet device 121 includes an intermediate perforated plate and a dual-speed water cap with a water cap gap of 0.25mm ± 0.05mm. The intermediate discharge device 122 includes a main branch pipe and a trapezoidal winding wire arranged on the main branch pipe with a winding wire gap of 0.25mm ± 0.05mm. The water inlet N1 located at the lower part of the tank 10 is connected to the water inlet device 14 and the softening bed unit water outlet device 121, and the intermediate discharge port N7 located in the middle of the tank 10 is connected to the intermediate discharge device 122.

[0046] Specifically, the inlet N1 is located at the bottom of the tank and connects to the inlet device 14 and the intermediate water distribution unit 12, for the inlet of wastewater to be treated. The intermediate outlet N7 is located in the middle of the tank and connects to the intermediate outlet device 122, for the discharge of regenerated wastewater and preliminary backwash water.

[0047] Specifically, the intermediate perforated plate and dual-speed water cap of the softening bed unit water outlet device 121 are both made of SS31603 material. The softening bed unit water outlet device 121 also functions as the softening bed water outlet device and the security filter water inlet device 14, ensuring uniform water distribution and preventing ion exchange resin leakage into the filter unit. The main branch pipe and trapezoidal winding wire of the intermediate discharge device 122 are also made of SS31603 material, with a winding gap of 0.25mm±0.05mm. The intermediate discharge device 122 is used for the discharge of resin regeneration wastewater and the discharge of preliminary backwash water from the security filter, optimizing the backwashing and regeneration process.

[0048] In this embodiment, the resin softening unit 13 is filled with resin and adopts a floating bed operation mode, which has a large water processing capacity and matches the water processing capacity of the folded backwashable filter cartridge 112. The backwash drain N4 located at the bottom of the tank 10, the resin inlet N9 located in the middle of the tank 10, the resin outlet N10 located at the bottom of the tank 10, and the regeneration liquid inlet N5 located at the bottom of the tank 10 are respectively connected to the resin softening unit 13.

[0049] Specifically, the backwash drain outlet N4 is located at the bottom of the tank and is connected to the resin softening unit 13 for discharging backwash water during regeneration; the resin inlet N9 is located in the middle of the tank and is used for filling ion exchange resin; the resin outlet N10 is located at the bottom of the tank and is used for resin replacement and maintenance discharge; the regenerated liquid inlet N5 is located at the bottom of the tank and is connected to the resin layer for the regenerated liquid to enter (the regenerated acid has a dissolving and removing effect on inorganic scale on the filter element).

[0050] Specifically, the resin softening unit 13 is filled with weak acid cation exchange resin or sodium ion exchange resin. The resin softening unit 13 is not less than 1000 mm high and adopts a floating bed operation mode. It has a large water treatment capacity and matches the water treatment capacity of the backwashable filter cartridge. The resin softening unit 13 is used to remove the residual hardness of the effluent from the high-density tank. It can reduce the hardness of the influent (calculated as CaCO3) from tens of mg / L to below 2 mg / L, which meets the anti-scaling requirements of the subsequent membrane system.

[0051] In this embodiment, the water inlet device 14 includes a lower perforated plate and a dual-speed water cap with a gap of 0.25mm ± 0.05mm. The water inlet device 14 is connected to the water inlet N1 located at the bottom of the tank 10, and the water inlet N1 is used for the wastewater to be treated to enter.

[0052] Specifically, the lower perforated plate and the dual-speed water cap are both made of SS31603 material.

[0053] Specifically, an inlet valve V1 is installed on the connecting pipe between the inlet N1 and the inlet device 14; a product water valve V2 is installed on the connecting pipe between the outlet N2 and the security filter unit 11; a backwash inlet valve V3 is installed on the connecting pipe between the backwash inlet N3 and the security filter unit 11; a backwash outlet valve V4 is installed on the connecting pipe between the backwash outlet N4 and the resin softening unit 13; a regenerated liquid inlet valve V5 is installed on the connecting pipe between the regenerated liquid inlet N5 and the resin softening unit 13; an exhaust valve V6 is installed on the connecting pipe between the exhaust outlet N6 and the upper end cap; a middle exhaust valve V7 is installed on the connecting pipe between the intermediate discharge outlet N7 and the intermediate discharge device 122; and an unqualified water discharge valve V8 is installed on the connecting pipe between the upper unqualified water discharge outlet N8 and the security filter unit 11.

[0054] Specifically, the water produced by the hardness removal purification device can meet the following indicators: hardness: ≤2mg / L; sludge density index: ≤4; turbidity: ≤0.2NTU.

[0055] Specifically, the resin is a weak acid cation exchange resin or a sodium ion exchange resin.

[0056] In this embodiment, the operation process of a hardness removal and purification device for wastewater before membrane concentration is described as follows:

[0057] 1. Normal operating procedure

[0058] Open the inlet valve V1 and the vent valve V6 to fill the tank 10 with water. After the tank 10 is full of water, open the upper unqualified water discharge valve V8 and close the vent valve V6. After the product water quality (hardness, SDI, turbidity) is qualified, open the product water valve V2 and close the upper unqualified discharge valve V8 to enter the normal product water state.

[0059] The wastewater to be treated enters through inlet N1, is evenly distributed through the bottom water distribution unit, and flows upward through the ion exchange softening unit. The resin adsorbs and removes calcium and magnesium ions from the water, thus removing hardness. The softened water enters the security filter unit 11 through the intermediate water distribution unit 12. It passes through a 5μm backwashable filter element to intercept tiny particles and broken resin. The purified water is output through outlet N2 and directly enters the reverse osmosis high-pressure pump, eliminating the need for an intermediate water tank and a low-pressure feed water pump.

[0060] 2. Backwashing and regeneration process

[0061] When the differential pressure of the unit exceeds the limit (filter blockage) or the resin adsorption is saturated, backwashing and regeneration operations are performed:

[0062] Close the inlet valve V1 and the product water valve V2, and open the backwash inlet valve V3, the middle drain valve V7, and the backwash discharge valve V4 to perform backwashing: backwash water enters through N3 and flows downward to rinse the backwash filter element 112 and the resin layer 13. Most of the initial backwash water is discharged through the middle discharge port N7. After 3 minutes, close the middle drain valve V7 and continue backwashing for 5-10 minutes to thoroughly rinse the filter element and the resin layer 13. The backwash wastewater is discharged through the N4 backwash drain port N4.

[0063] After backwashing, close the above valves, open the intermediate drain valve V7, exhaust valve V6, and regenerated liquid inlet valve V5. The regenerated liquid enters through N5 and flows downward through the softening resin unit 13 to complete resin regeneration. The regeneration time is not less than 30 minutes. The regenerated waste liquid is discharged through the intermediate discharge port N7.

[0064] After regeneration is complete, close the acid inlet valve in the regenerated liquid and keep other valves in their positions to replace the regenerated waste liquid. After replacement, close the regenerated liquid inlet valve V5, open the water inlet valve V1 and the upper discharge valve V8, and perform a forward flush for about 5 minutes. Take a sample to test the quality of the flushing water. If it passes the test, switch to standby or put it into operation.

[0065] Example 1: Application of zero-discharge pretreatment of wastewater from gas-fired power plants

[0066] For a zero-discharge wastewater project of a gas-fired power plant, the influent is the effluent from a high-density tank with the following water quality parameters: hardness (calculated as CaCO3) 30-50 mg / L, SDI 8-12, and turbidity 2-5 NTU. It needs to be treated to hardness ≤2 mg / L, SDI ≤4, and turbidity ≤0.2 NTU before entering the reverse osmosis concentration system.

[0067] The integrated hardness removal and purification device of the present invention has the following specifications for the tank 10: diameter 2.5m, height 8m, design pressure 0.6MPa; the interior is filled with sodium ion exchange resin with a layer height of 1200mm; the security filter unit 11 is equipped with a 5μm pleated backwashable PP filter element with a total filtration area of ​​20m².

[0068] Operating parameters:

[0069] Water treatment capacity: 100 m³ / h;

[0070] Normal operation: Inlet water pressure 0.4MPa, the product water directly enters the reverse osmosis high-pressure pump, without the need for an intermediate water tank and a low-pressure feed water pump;

[0071] Backwash cycle: 24 hours, backwash intensity: 15L / (m²・s), backwash time: 10 minutes;

[0072] Regeneration cycle: 24 hours, using 5% hydrochloric acid solution for regeneration, regeneration time 40 minutes, and regeneration waste liquid is collected and treated through intermediate discharge port N7.

[0073] Processing effect:

[0074] The hardness of the produced water is 0.8-1.5 mg / L (calculated as CaCO3), which is far below the requirement of 2 mg / L.

[0075] The product water has an SDI of 2-3 and a turbidity of 0.1-0.15 NTU, which fully meets the feed water requirements of the reverse osmosis system.

[0076] Filter cartridge lifespan: After 12 months of continuous operation, the pressure difference remains within 0.1MPa, and no replacement is required;

[0077] Energy saving effect: Compared with the traditional split-type solution, the low-pressure water pump (power 15kW) is eliminated, saving about 130,000 kWh of electricity per year;

[0078] Space saving: The total footprint is only 8m², while the traditional split-type solution occupies 20m², saving 60% of the space.

[0079] Cost savings: Annual savings of approximately RMB 120,000 in filter purchase and replacement costs, and 30% savings in equipment investment.

[0080] Example 2: Application of membrane concentration pretreatment for high-hardness industrial wastewater

[0081] A chemical company's high-hardness industrial wastewater treatment project has an influent hardness (calculated as CaCO3) of 80-100 mg / L, which needs to be treated before entering a reverse osmosis + electrodialysis + evaporation crystallization zero-discharge system.

[0082] The device of this invention has the following specifications: tank 10, diameter 3.2m, height 10m, design pressure 0.8MPa; filled with weak acid cation exchange resin, layer height 2000mm; equipped with 5μm backwashable filter element, total filtration area 30m².

[0083] Running result:

[0084] The hardness of the produced water is stable at ≤1.8 mg / L (calculated as CaCO3), SDI ≤3.5, and turbidity ≤0.18 NTU;

[0085] The backwashing and regeneration cycles are synchronized at 20 hours, making operation and maintenance convenient;

[0086] Compared to traditional solutions, eliminating the need for a softening tank, low-pressure water pump, and resin trap reduces equipment investment by 35%, annual maintenance costs by 40%, and energy consumption by 25%.

[0087] In summary, the technical solution of this application has the following beneficial effects:

[0088] 1. This device adopts an integrated design, significantly saving space: This application combines the traditional softening bed and security filter into a single pressure vessel, achieving a deep integration of hardening removal and filtration functions. This design, while ensuring treatment effectiveness, significantly reduces equipment footprint, lowers operating costs, and improves system energy efficiency.

[0089] 2. This device comprehensively saves on equipment investment: it eliminates the need for resin traps, softening tanks, and reverse osmosis low-pressure feed pumps in traditional processes, reducing equipment procurement costs and investment in supporting pipelines and electrical systems, while also eliminating the risk of secondary pollution from the softening tank.

[0090] 3. This application significantly reduces operation and maintenance costs: The security filter adopts a pleated backwashable filter element, replacing the traditional disposable filter element, with a normal service life of up to 1 year, avoiding the procurement and labor costs of frequent replacements; at the same time, the regenerated acid can dissolve inorganic scale on the surface of the filter element, extending the service life of the filter element.

[0091] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A hardness removal and purification device for wastewater before membrane concentration, characterized in that, Including the tank body, The main body of the tank includes a cover and a matching tank body detachably connected to the cover. The top of the cover is provided with a detachable upper end cap, and the bottom of the tank body is provided with a lower end cap. The tank is equipped with, from top to bottom, a security filtration unit, a middle water distribution unit, a resin softening unit, and a water inlet device. The security filter unit includes an upper perforated plate and a foldable backwashable filter element that can be detachably installed below the upper perforated plate. The water outlet, the upper unqualified water discharge port, and the backwash water inlet located at the top of the tank are all connected to the security filter unit. The water outlet is used for the output of water produced after softening and filtration by the security filter unit. The upper unqualified water discharge port is used for the security filter unit to discharge unqualified water produced during initial startup and for the discharge of forward wash water. The backwash water inlet is used for the entry of backwash water. The intermediate water distribution unit includes a softening bed unit water outlet device and an intermediate discharge device arranged in parallel. The softening bed unit water outlet device includes an intermediate perforated plate and a dual-speed water cap. The intermediate discharge device includes a main branch pipe and a trapezoidal winding wire arranged on the main branch pipe. The water inlet located at the lower part of the tank body is connected to the intermediate water distribution device, and the intermediate discharge port located in the middle of the tank body is connected to the intermediate discharge device. The resin softening unit is filled with resin and adopts a floating bed operation mode, which has a large water processing capacity and matches the water processing capacity of the foldable backwashable filter cartridge. The backwash inlet located at the bottom of the tank, the resin inlet located in the middle of the tank, the resin outlet located at the bottom of the tank, and the regeneration liquid inlet located at the bottom of the tank are respectively connected to the resin softening unit. The water inlet device includes a lower perforated plate and a dual-speed water cap. The water inlet device is connected to a water inlet located at the bottom of the tank, and the water inlet is used for the wastewater to be treated to enter.

2. The hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, An inlet valve is provided on the pipe connecting the inlet to the outlet of the softening bed unit; a product water valve is provided on the pipe connecting the outlet to the security filter unit; a backwash inlet valve is provided on the pipe connecting the backwash inlet to the security filter unit; a backwash outlet valve is provided on the pipe connecting the backwash outlet to the softening resin unit; a regenerated liquid inlet valve is provided on the pipe connecting the regenerated liquid inlet to the softening resin unit; an exhaust valve is provided on the pipe connecting the exhaust port to the upper end cap; a middle exhaust valve is provided on the pipe connecting the intermediate discharge port to the intermediate discharge device; and an upper unqualified water discharge valve is provided on the pipe connecting the upper unqualified water discharge port to the security filter unit.

3. The hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The upper end cap is equipped with an exhaust port for filling the equipment with water and venting air during operation.

4. The hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The tank body is made of carbon steel lined with rubber, and its design pressure is ≤1MPa, which meets the requirements for pressure operation.

5. A hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The lower end cap is made of carbon steel lined with rubber. A bottom manhole is provided on the lower end cap for the inspection and maintenance of the bottom water inlet device and water cap.

6. A hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The upper end cap is a double-flange cantilever detachable structure, which facilitates the inspection and replacement of the internal filter element and perforated plate.

7. A hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The foldable backwashable filter element is made of PP material and has a filtration accuracy of 5μm.

8. A hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The water produced by the hardness removal and purification device can meet the following indicators: hardness: ≤2mg / L; sludge density index: ≤4; turbidity: ≤0.2NTU.

9. A hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The upper perforated plate, the middle perforated plate, and the lower perforated plate are all made of SS31603 material.

10. A hardness removal and purification device for wastewater before membrane concentration according to claim 1, characterized in that, The resin is a weak acid cation exchange resin or a sodium ion exchange resin.

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