Nickel-containing wastewater zero discharge system

Abstract

The utility model relates to a nickeliferous wastewater zero discharge system which is characterized in that an outlet of a clean water tank is connected with an immersed ultrafiltration tank, an ultrafiltration component is arranged at the bottom of the immersed ultrafiltration tank, a water producing end of the ultrafiltration component is connected with an inlet of an ultrafiltration water producing tank, and an outlet of the ultrafiltration water producing tank is connected with an inlet of a security filter; an outlet of the security filter is connected with an inlet of a first-stage reverse osmosis membrane, a water producing end of the first-stage reverse osmosis membrane is connected with an inlet of a first-stage reverse osmosis fresh water tank, a concentrated solution end of the first-stage reverse osmosis membrane is connected with an inlet of a first-stage reverse osmosis concentrated water tank, and an outlet of the first-stage reverse osmosis concentrated water tank is connected with an inlet of a second-stage reverse osmosis membrane; the water producing end of the second-stage reverse osmosis membrane is connected with the inlet of the first-stage reverse osmosis fresh water tank, the concentrated solution end of the second-stage reverse osmosis membrane is connected with the inlet of the second-stage reverse osmosis concentrated water tank, and the outlet of the second-stage reverse osmosis concentrated water tank is connected with the evaporator. The nickel-containing wastewater is separated through the membrane, the occupied area can be reduced while zero emission is achieved, the treatment cost is saved, and the method has industrial application prospects.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to a zero-discharge system for nickel-containing wastewater. Background Technology

[0002] Wastewater generated from the aluminum profile anodizing process contains nickel and tin. For the company, nickel and tin are not only substances that need to be treated in the wastewater, but also valuable heavy and precious metals. To meet the company's wastewater discharge requirements, the total nickel content and total tin content in the wastewater must not exceed 0.5 mg / L. Ideally, the treatment system can achieve zero discharge, in which case the treated liquid should be reused in the anodizing process or other processes. As reclaimed water, the water quality requirements generally include a pH of 6.5-8.5, DTS content below 300 mg / L, and COD content below 100 mg / L.

[0003] Chinese invention patent CN111499082A discloses an industrial wastewater treatment process based on electrolysis and membrane filtration, comprising the following steps: S1: pretreatment of collected industrial wastewater; S2: electrolytic oxidation of the industrial wastewater, followed by sludge filtration through electrocoagulation; S3: placement of the filtered sludge in a sludge tank, followed by sludge dewatering to obtain sludge; S4: filtration of the industrial wastewater containing the sludge through an ultrafiltration membrane to obtain permeate and concentrate, wherein the concentrate enters the sludge tank for subsequent dewatering; S5: treatment of the filtered permeate through reverse osmosis to obtain concentrated liquid; S6: reuse or discharge of residual permeate. This method uses electrolytic oxidation, which has high treatment costs and requires a large equipment footprint, making it unsuitable for enterprises with limited treatment space. Utility Model Content

[0004] To address the aforementioned problems, this invention provides a zero-discharge system for nickel-containing wastewater, characterized by its small footprint and low treatment cost. This system utilizes a submerged ultrafiltration tank and two-stage reverse osmosis to separate nickel salts, and the resulting dialysis solution can be reused in the anodizing process.

[0005] The specific plan is as follows:

[0006] A zero-discharge system for nickel-containing wastewater includes a clear water tank, a submerged ultrafiltration tank, a coagulant tank, an ultrafiltration permeate tank, a security filter, a primary reverse osmosis membrane, a primary reverse osmosis desalination tank, a primary reverse osmosis concentrate tank, a secondary reverse osmosis membrane, a secondary reverse osmosis concentrate tank, and an evaporator. The outlet of the clear water tank is connected to the submerged ultrafiltration tank. An ultrafiltration module is installed at the bottom of the submerged ultrafiltration tank. The submerged ultrafiltration tank is connected to the coagulant tank. The permeate end of the ultrafiltration module is connected to the inlet of the ultrafiltration permeate tank. The outlet of the ultrafiltration permeate tank is connected to the inlet of the security filter. The outlet of the security filter... The inlet of the first-stage reverse osmosis membrane is connected to the inlet of the first-stage reverse osmosis desalination tank, the concentrate end of the first-stage reverse osmosis membrane is connected to the inlet of the first-stage reverse osmosis concentrate tank, the outlet of the first-stage reverse osmosis concentrate tank is connected to the inlet of the second-stage reverse osmosis membrane, the product water end of the second-stage reverse osmosis membrane is connected to the inlet of the first-stage reverse osmosis desalination tank, the concentrate end of the second-stage reverse osmosis membrane is connected to the inlet of the second-stage reverse osmosis concentrate tank, the outlet of the second-stage reverse osmosis concentrate tank is connected to the evaporator, and the condensate outlet of the evaporator is connected to the inlet of the first-stage reverse osmosis desalination tank.

[0007] Furthermore, the bottom of the clear water tank is filled with a quartz sand filter layer, and the outlet of the clear water tank is located below the quartz sand filter layer.

[0008] Furthermore, the ultrafiltration module includes a hollow fiber membrane, wherein the hollow fibers in the hollow fiber membrane have an inner diameter of 0.5 to 1.0 mm and an outer diameter of 1.5 to 2.0 mm.

[0009] Furthermore, the hollow fiber membrane is a PVDF hollow fiber membrane with a pore size of 0.01 to 0.03 micrometers.

[0010] Furthermore, the security filter is filled with a filter element with a precision of 2 to 6 micrometers.

[0011] Furthermore, the primary reverse osmosis membrane is a polyamide reverse osmosis membrane, and the polyamide reverse osmosis membranes are arranged in a 2:1 ratio, forming a primary two-stage structure.

[0012] Furthermore, the secondary reverse osmosis membrane is a STRO membrane, and the STRO membrane is connected to a booster pump.

[0013] Furthermore, the evaporator is a low-temperature vacuum evaporator.

[0014] By adopting the aforementioned technical solution, compared with the prior art, this utility model can eliminate the need for sand filtration, security filtration and other devices by designing a submerged ultrafiltration tank. At the same time, the ultrafiltration components are set at the bottom of the submerged ultrafiltration tank, which can realize component integration and reduce the equipment footprint.

[0015] Furthermore, this invention obtains water that meets reuse requirements by connecting a first-stage reverse osmosis membrane and a second-stage STRO membrane in series, achieving zero discharge and complying with environmental protection requirements. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system structure provided in Embodiment 1 of this utility model. Detailed Implementation

[0017] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this utility model, not all embodiments, and are only used to illustrate this utility model, and should not be regarded as limiting the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0018] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0020] Example 1:

[0021] refer to Figure 1A zero-discharge system for nickel-containing wastewater includes a clear water tank 1, a submerged ultrafiltration tank 2, an ultrafiltration module 3, a coagulant tank 4, an ultrafiltration permeate tank 5, a security filter 6, a primary reverse osmosis membrane 7, a primary reverse osmosis desalination tank 8, a primary reverse osmosis concentrate tank 9, a secondary reverse osmosis membrane 10, a secondary reverse osmosis concentrate tank 11, and an evaporator 12. The outlet of the clear water tank 1 is connected to the submerged ultrafiltration tank 2. The bottom of the submerged ultrafiltration tank 2 is equipped with the ultrafiltration module 3. The submerged ultrafiltration tank 2 is connected to the coagulant tank 4. The permeate end of the ultrafiltration module 3 is connected to the inlet of the ultrafiltration permeate tank 5, and the outlet of the ultrafiltration permeate tank 5 is connected to the inlet of the security filter 6. The outlet of the security filter 6 is connected to the inlet of the primary reverse osmosis membrane 7. The permeate end of the primary reverse osmosis membrane 7 is connected to the inlet of the primary reverse osmosis desalination tank 8. The concentrate end of the primary reverse osmosis membrane 7 is connected to the inlet of the primary reverse osmosis concentrate tank 9. The outlet of the primary reverse osmosis concentrate tank 9 is connected to the inlet of the secondary reverse osmosis membrane 10. The permeate end of the secondary reverse osmosis membrane 10 is connected to the inlet of the primary reverse osmosis desalination tank 8. The concentrate end of the secondary reverse osmosis membrane 10 is connected to the inlet of the secondary reverse osmosis concentrate tank 11. The outlet of the secondary reverse osmosis concentrate tank 11 is connected to the evaporator 12. The condensate outlet of the evaporator 12 is connected to the inlet of the primary reverse osmosis desalination tank 8.

[0022] This invention targets nickel-containing wastewater that may also contain other metallic contaminants, such as aluminum or tin, as long as the membrane treatment separation principle for these other metallic contaminants is essentially the same as that for nickel. To achieve zero discharge, the wastewater (e.g., wastewater from a nickel-plated workpiece rinsing tank) is transported to this nickel-containing wastewater zero-discharge system. After separation and treatment, the resulting membrane dialysis solution is collected in a primary reverse osmosis desalination tank and can be returned to the rinsing tank for reuse. Thus, a closed-loop recycling system is achieved.

[0023] In this invention, the bottom of the clear water tank is filled with a quartz sand filter layer, and the outlet of the clear water tank is located below the quartz sand filter layer. Using quartz sand as the filter medium, under certain pressure, water with high turbidity is filtered through a certain thickness of granular or non-granular quartz sand, effectively removing suspended matter and solid particles from the water. Depending on the water production rate, quartz sand of different mesh sizes (different diameter quartz sand particles) is required. These are used for water treatment turbidity removal, water softening, and pre-treatment of pure water, achieving an effluent turbidity of less than 3 degrees.

[0024] This invention employs a submerged ultrafiltration tank, which saves floor space and reduces treatment costs. Typically, wastewater undergoes pretreatment in a clear water tank and then requires a sand filter and a security filter before being transported to the ultrafiltration membrane separation equipment. However, this invention uses a submerged ultrafiltration tank, placing the ultrafiltration module within the tank, eliminating the need for sand filters and security filters, thus reducing equipment investment and floor space requirements. The ultrafiltration module comprises a hollow fiber membrane, preferably a PVDF hollow fiber membrane, which can withstand acid and alkaline solutions with pH values ​​of 0-14, as well as oxidizing agents and organic solvents of any concentration. It can withstand frequent high-intensity chemical cleaning and exhibits good recoverability. Specifically, the pore size of the hollow fiber membrane is 0.01 to 0.03 micrometers, the inner diameter of the hollow fiber in the hollow fiber membrane is 0.5 to 1.0 mm, and the outer diameter is 1.5 to 2.0 mm. This type of hollow fiber membrane has high core hardness and can withstand wastewater with a suspended solids concentration of 1% to 3%, including wastewater containing chemical precipitates, without causing damage or fouling to the membrane core.

[0025] In this invention, the primary reverse osmosis membrane mainly removes most of the high-valence anions and cations, organic matter, pyrogens, and bacteria from the water. To protect the reverse osmosis membrane, a security filter with a precision of 2-6 micrometers is installed at its inlet. The primary reverse osmosis membrane is a polyamide reverse osmosis membrane, which has anti-fouling advantages. The polyamide reverse osmosis membranes are arranged in a 2:1 ratio, forming a two-stage primary system. Each unit uses three fiberglass pressure vessels to meet the separation requirements, and the obtained product water meets the water quality requirements.

[0026] In this invention, the secondary reverse osmosis membrane is a STRO membrane, which is connected to a booster pump. The STRO membrane traps small particulate matter and dissolved ions in the liquid on the concentrate side, while the permeated desalination water is collected as clean filtrate and combined with the permeate from the primary reverse osmosis membrane. Using a STRO network-type reverse osmosis membrane not only achieves a desalination rate of 99% but also boasts high membrane packing density, a smaller equipment footprint, and reduced engineering costs.

[0027] In this invention, the evaporator is preferably a low-temperature vacuum evaporator. Waste liquid enters the low-temperature evaporator and evaporates at a lower temperature. The steam is discharged, cooled, and condensed to form distilled water. The concentrated water is returned to a collection tank or entrusted to an external unit for treatment. This process can remove heavy metals and most inorganic salts. The preferred model is LT-30T, with a working vacuum degree of -0.093 to -0.098 MPa and an evaporation temperature of 35 to 40°C.

[0028] Through this system, the water quality indicators collected by the primary reverse osmosis freshwater tank include pH 6.5-8.5, DTS content below 300 mg / L, and COD content below 100 mg / L, meeting the requirements for reused water.

[0029] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A zero-discharge system for nickel-containing wastewater, characterized in that: The system includes a clear water tank, a submerged ultrafiltration tank, a coagulant tank, an ultrafiltration permeate tank, a security filter, a primary reverse osmosis membrane, a primary reverse osmosis desalination tank, a primary reverse osmosis concentrate tank, a secondary reverse osmosis membrane, a secondary reverse osmosis concentrate tank, and an evaporator. The outlet of the clear water tank is connected to the submerged ultrafiltration tank. An ultrafiltration module is installed at the bottom of the submerged ultrafiltration tank. The submerged ultrafiltration tank is connected to the coagulant tank. The permeate end of the ultrafiltration module is connected to the inlet of the ultrafiltration permeate tank. The outlet of the ultrafiltration permeate tank is connected to the inlet of the security filter. The outlet of the security filter is connected to the primary reverse osmosis membrane. The inlet of the reverse osmosis membrane is connected to the inlet of the first-stage reverse osmosis desalination tank, the concentrate end of the first-stage reverse osmosis membrane is connected to the inlet of the first-stage reverse osmosis concentrate tank, the outlet of the first-stage reverse osmosis concentrate tank is connected to the inlet of the second-stage reverse osmosis membrane, the product water end of the second-stage reverse osmosis membrane is connected to the inlet of the first-stage reverse osmosis desalination tank, the concentrate end of the second-stage reverse osmosis membrane is connected to the inlet of the second-stage reverse osmosis concentrate tank, the outlet of the second-stage reverse osmosis concentrate tank is connected to the evaporator, and the condensate outlet of the evaporator is connected to the inlet of the first-stage reverse osmosis desalination tank.

2. The zero-discharge system for nickel-containing wastewater according to claim 1, characterized in that: The bottom of the clear water tank is filled with a quartz sand filter layer, and the outlet of the clear water tank is located below the quartz sand filter layer.

3. The zero-discharge system for nickel-containing wastewater according to claim 1, characterized in that: The ultrafiltration module includes a hollow fiber membrane, wherein the hollow fibers in the hollow fiber membrane have an inner diameter of 0.5 to 1.0 mm and an outer diameter of 1.5 to 2.0 mm.

4. The zero-discharge system for nickel-containing wastewater according to claim 3, characterized in that: The hollow fiber membrane is a PVDF hollow fiber membrane with a pore size of 0.01 to 0.03 micrometers.

5. The zero-discharge system for nickel-containing wastewater according to claim 1, characterized in that: The security filter is filled with a filter element with a precision of 2 to 6 micrometers.

6. The zero-discharge system for nickel-containing wastewater according to claim 5, characterized in that: The primary reverse osmosis membrane is a polyamide reverse osmosis membrane, and the polyamide reverse osmosis membranes are arranged in a 2:1 ratio, forming a primary two-stage structure.

7. The zero-discharge system for nickel-containing wastewater according to claim 5, characterized in that: The secondary reverse osmosis membrane is a STRO membrane, and the STRO membrane is connected to a booster pump.

8. The zero-discharge system for nickel-containing wastewater according to any one of claims 1-7, characterized in that: The evaporator is a low-temperature vacuum evaporator.

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