High-salt-content wastewater treatment system for photovoltaic industry

Abstract

The utility model discloses a high-salt-content wastewater treatment system in the photovoltaic industry. The device comprises a strong brine inlet pipe, an adjusting tank, a first-stage silicon removal sedimentation tank, a hardness removal sedimentation tank, a first-stage dissolved air flotation device, a first-stage ultrafiltration membrane, a weak acid cation bed, a first-stage reverse osmosis membrane, a decarburization device, a second-stage silicon removal sedimentation tank, a second-stage dissolved air flotation device, a second-stage ultrafiltration membrane, a second-stage reverse osmosis membrane, a first-stage nanofiltration membrane, a second-stage nanofiltration membrane and a catalytic oxidation device. The pretreatment system has the advantages that product water treated by the pretreatment system for the high-salt-content wastewater in the photovoltaic industry is recycled for production, the treated strong brine is used as raw water for evaporative crystallization, and high-quality industrial byproduct salt is obtained after further concentration by the evaporation system, so that zero discharge of the wastewater is realized; meanwhile, the primary dissolved air flotation device, the secondary dissolved air flotation device, the hardness removal sedimentation tank and the silicon removal sedimentation tank are matched to perform floating and sedimentation treatment on suspended matters in the wastewater, so that the technical problems existing in sand filtration at present are solved.

Description

Technical Field

[0001] The utility model relates to the field of wastewater treatment, in particular to a high-salt wastewater treatment system for the photovoltaic industry. Background Technique

[0002] A large amount of chemical substances, such as hydrofluoric acid, nitric acid, hydrochloric acid, etc., are required in the production process of photovoltaic modules for cleaning and etching photovoltaic glass, silicon wafers, and metal conduction. A large amount of wastewater will be generated during the use of these chemical substances, which contains a large amount of harmful substances such as fluorine, silicon, chlorine ions, and heavy metal ions. With the rapid development of the solar photovoltaic industry, the problem of photovoltaic wastewater has gradually emerged. Photovoltaic wastewater mainly comes from a series of wastewater generated during the production of photovoltaic modules and the operation and maintenance of power stations.

[0003] However, in the current treatment process, there are still a large number of substances that are difficult to settle suspended in the water in the effluent area of the high-density sedimentation tank, which cannot be completely removed by relying on the residence time in the clarification area. As a result, after the effluent of the high-density sedimentation tank enters the sand filter, the sand filter needs to be frequently cleaned (positive washing, backwashing, air washing). If the sand filter is not cleaned in time, the subsequent resin softening and membrane concentration devices will inevitably be contaminated to varying degrees. At the same time, multiple sets of sand filters occupy a large area. If the sand filter is not flushed in time, it will cause subsequent membrane pollution, frequent flushing times, affect the production capacity, have a small interception rate for small molecule pollutants, and cause irreversible pollution to the membrane system. Content of the Utility Model

[0004] The purpose of the utility model is to provide a high-salt wastewater treatment system for the photovoltaic industry.

[0005] The utility model is implemented by the following technical solutions: A high-salt wastewater treatment system for the photovoltaic industry, which includes a concentrated brine inlet pipe, an adjustment tank, a primary silicon removal sedimentation tank, a hardness removal sedimentation tank, a primary dissolved air flotation device, a primary ultrafiltration membrane, a weak acid cation bed, a primary reverse osmosis membrane, a decarbonator, a secondary silicon removal sedimentation tank, a secondary dissolved air flotation device, a secondary ultrafiltration membrane, a secondary reverse osmosis membrane, a primary nanofiltration membrane, a secondary nanofiltration membrane, and a catalytic oxidation device;

[0006] The inlet of the regulating tank is connected to the concentrated brine inlet pipe. The outlet of the regulating tank is connected to the inlet pipeline of the first silicon removal sedimentation tank. The outlet of the first silicon removal sedimentation tank is connected to the inlet pipeline of the hardness removal sedimentation tank. The outlet of the hardness removal sedimentation tank is connected to the inlet pipeline of the first dissolved air flotation device. The outlet of the first dissolved air flotation device is connected to the inlet pipeline of the first ultrafiltration membrane. The outlet of the first ultrafiltration membrane is connected to the inlet pipeline of the weak acid cation bed. The outlet of the weak acid cation bed is connected to the inlet pipeline of the first reverse osmosis membrane. The concentrated water outlet of the first reverse osmosis membrane is connected to the inlet pipeline of the decarbonator. The produced water outlet of the decarbonator is connected to the inlet pipeline of the second silicon removal sedimentation tank. The outlet of the second silicon removal sedimentation tank is connected to the inlet pipeline of the second dissolved air flotation device. The outlet of the second dissolved air flotation device is connected to the inlet pipeline of the second ultrafiltration membrane. The outlet of the second ultrafiltration membrane is connected to the inlet pipeline of the second reverse osmosis membrane. The concentrated water outlet of the second reverse osmosis membrane is connected to the inlet pipeline of the first nanofiltration membrane. The produced water outlet of the first nanofiltration membrane is connected to the inlet pipeline of the storage tank of the sodium chloride evaporation system. The concentrated water outlet of the first nanofiltration membrane is connected to the inlet pipeline of the second nanofiltration membrane. The concentrated water outlet of the second nanofiltration membrane is connected to the inlet pipeline of the catalytic oxidation device. The outlet of the catalytic oxidation device is connected to the inlet pipeline of the storage tank of the sodium sulfate evaporation system.

[0007] Further, a sludge thickening tank is also included. The sludge discharge ports of the first silicon removal sedimentation tank, the hardness removal sedimentation tank, the scum outlets of the first dissolved air flotation device and the second dissolved air flotation device, and the scum outlet of the second silicon removal sedimentation tank are respectively connected to the inlet pipeline of the sludge thickening tank. The filtrate outlet of the sludge thickening tank is connected to the inlet pipeline of the regulating tank.

[0008] Further, the concentrated water outlet of the first ultrafiltration membrane is connected to the inlet pipeline of the regulating tank.

[0009] Further, the produced water outlet of the second reverse osmosis is connected to the inlet pipeline of the pure water reverse osmosis membrane. The produced water outlet of the pure water reverse osmosis membrane is connected to the inlet pipeline of the recycled water tank. The concentrated water outlet of the pure water reverse osmosis membrane is connected to the inlet pipeline of the first reverse osmosis membrane.

[0010] Further, the produced water outlet of the first reverse osmosis membrane is connected to the inlet pipeline of the recycled water tank.

[0011] Further, the produced water outlet of the second nanofiltration membrane is connected to the inlet pipeline of the first nanofiltration membrane.

[0012] Advantages of the present utility model: The product water treated by the pretreatment system for highly saline wastewater in the photovoltaic industry is used for production reuse, and the concentrated brine after treatment is used as the raw water for evaporation and crystallization. After further concentration by the evaporation system, high-quality industrial by-product salt is obtained, realizing zero discharge of wastewater. At the same time, through the combined action of the first dissolved air flotation device, the second dissolved air flotation device, the hardness removal sedimentation tank, and the silicon removal sedimentation tank, the suspended solids in the wastewater are floated and settled, solving the technical problems existing in the current use of sand filtration. After treating the suspended solids, the service life of the subsequent membrane treatment device is extended. Brief Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0014] Figure 1 It is a structural schematic diagram of the utility model;

[0015] In the figure: regulating tank 1, concentrated brine inlet pipe 2, first silicon removal sedimentation tank 3, hardness removal sedimentation tank 4, first dissolved air flotation device 5, first ultrafiltration membrane 6, weak acid cation exchanger 7, first reverse osmosis membrane 8, decarbonator 9, second dissolved air flotation device 10, second ultrafiltration membrane 11, second reverse osmosis membrane 12, first nanofiltration membrane 13, sodium chloride evaporation system 14, second nanofiltration membrane 15, catalytic oxidation device 16, sludge thickening tank 18, pure water reverse osmosis membrane 19, recycled water tank 20. Detailed Embodiments

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0017] As Figure 1 shown, the highly saline wastewater treatment system in the photovoltaic industry includes a concentrated brine inlet pipe 2, a regulating tank 1, a first silicon removal sedimentation tank 3, a hardness removal sedimentation tank 4, a first dissolved air flotation device 5, a first ultrafiltration membrane 6, a weak acid cation exchanger 7, a first reverse osmosis membrane 8, a decarbonator 9, a second silicon removal sedimentation tank 21, a second dissolved air flotation device 10, a second ultrafiltration membrane 11, a second reverse osmosis membrane 12, a first nanofiltration membrane 13, a second nanofiltration membrane 15, and a catalytic oxidation device 16;

[0018] The inlet of the regulating tank 1 is connected to the concentrated brine inlet pipe 2. The outlet of the regulating tank 1 is connected to the inlet pipeline of the first-stage silicon removal sedimentation tank 3. The outlet of the first-stage silicon removal sedimentation tank 3 is connected to the inlet pipeline of the hardness removal sedimentation tank 4. The outlet of the hardness removal sedimentation tank 4 is connected to the inlet pipeline of the first-stage dissolved air flotation device 5. The outlet of the first-stage dissolved air flotation device 5 is connected to the inlet pipeline of the first-stage ultrafiltration membrane 6. The outlet of the first-stage ultrafiltration membrane 6 is connected to the inlet pipeline of the weak acid cation bed 7. The outlet of the weak acid cation bed 7 is connected to the inlet pipeline of the first-stage reverse osmosis membrane 8. The concentrated water outlet of the first-stage reverse osmosis membrane 8 is connected to the inlet pipeline of the decarbonator 9. The produced water outlet of the decarbonator 9 is connected to the inlet pipeline of the second-stage silicon removal sedimentation tank 21. The outlet of the second-stage silicon removal sedimentation tank 21 is connected to the inlet pipeline of the second-stage dissolved air flotation device 10. The outlet of the second-stage dissolved air flotation device 10 is connected to the inlet pipeline of the second-stage ultrafiltration membrane 11. The outlet of the second-stage ultrafiltration membrane 11 is connected to the inlet pipeline of the second-stage reverse osmosis membrane 12. The concentrated water outlet of the second-stage reverse osmosis membrane 12 is connected to the inlet pipeline of the first-stage nanofiltration membrane 13. The produced water outlet of the first-stage nanofiltration membrane 13 is connected to the inlet pipeline of the storage tank of the sodium chloride evaporation system 14. The concentrated water outlet of the first-stage nanofiltration membrane 13 is connected to the inlet pipeline of the second-stage nanofiltration membrane 15. The concentrated water outlet of the second-stage nanofiltration membrane 15 is connected to the inlet pipeline of the catalytic oxidation device 16. The outlet of the catalytic oxidation device 16 is connected to the inlet pipeline of the storage tank of the sodium sulfate evaporation system 17.

[0019] It also includes a sludge thickening tank 18. The sludge discharge ports of the first-stage silicon removal sedimentation tank 3, the hardness removal sedimentation tank 4, the scum outlets of the first-stage dissolved air flotation device 5, the scum outlets of the second-stage dissolved air flotation device 10, and the scum outlets of the second-stage silicon removal sedimentation tank 21 are respectively connected to the inlet pipeline of the sludge thickening tank 18. The filtrate outlet of the sludge thickening tank 18 is connected to the inlet pipeline of the regulating tank 1.

[0020] The concentrated water outlet of the first-stage ultrafiltration membrane 6 is connected to the inlet pipeline of the regulating tank 1.

[0021] The produced water outlet of the second-stage reverse osmosis membrane 12 is connected to the inlet pipeline of the pure water reverse osmosis membrane 19. The produced water outlet of the pure water reverse osmosis membrane 19 is connected to the inlet pipeline of the recycled water tank 20. The concentrated water outlet of the pure water reverse osmosis membrane 19 is connected to the inlet pipeline of the first-stage reverse osmosis membrane 8.

[0022] The produced water outlet of the first-stage reverse osmosis membrane 8 is connected to the inlet pipeline of the recycled water tank 20.

[0023] The produced water outlet of the second-stage nanofiltration membrane 15 is connected to the inlet pipeline of the first-stage nanofiltration membrane 13.

[0024] The product water treated by the pretreatment system for highly saline wastewater in the photovoltaic industry is used for production reuse, and the treated concentrated brine is used as the raw water for evaporation and crystallization. After further concentration by the evaporation system, high-quality industrial by-product salt is obtained, realizing zero discharge of wastewater. At the same time, the cooperation of the first-stage dissolved air flotation device 5, the second-stage dissolved air flotation device 10, the hardening removal sedimentation tank 4 and the silicon removal sedimentation tank 3 settles the suspended solids in the wastewater, solves the current problem of using sand filtration technology, and prolongs the service life of the subsequent membrane treatment device after treating the suspended solids.

[0025] The specific operation process of this embodiment:

[0026] The highly saline wastewater in the photovoltaic industry enters the regulation tank 1 through a lift pump. The regulation tank 1 is equipped with a mixer to play a role in equalizing the quantity and quality. The wastewater after equalizing the quantity and quality enters the first-stage silicon removal sedimentation tank 3 through a lift pump. The first-stage silicon removal sedimentation tank 3 is successively composed of a reaction zone, a coagulation zone, a flocculation zone, and a sedimentation zone in series. The pH is adjusted to 9.5 - 10.5 by adding lime, and magnesium oxide is added to remove silicon. The surface of the magnesium hydroxide precipitation particles adsorbs the silicon compounds in the wastewater to form insoluble magnesium silicate precipitation, thereby removing silicon. Since the formed precipitate has a slow sedimentation rate, in order to accelerate the precipitation rate, PFS and PAM are added for coagulation to increase the specific gravity of the flocs. The effluent overflows through the overflow port to the hardening removal sedimentation tank 4, and the sludge formed in the sedimentation zone settles to the bottom and is transported to the sludge thickening tank 18 by a sludge discharge pump;

[0027] The silicon removal effluent enters the hardening removal sedimentation tank 4. The structure of the hardening removal sedimentation tank 4 is the same as that of the silicon removal sedimentation tank 3, but different chemicals are added. The pH of the influent is adjusted to 11.2 - 11.5. At this time, the alkalinity mainly exists in the form of carbonate ions. Further adding sodium carbonate makes the calcium ions in the wastewater combine with carbonate ions to form calcium carbonate precipitation, so as to achieve the purpose of removing hardness;

[0028] The water from the sludge thickening tank 18 contains a small amount of suspended solids and sludge particles that are difficult to settle by their own weight and remain suspended in the water for a long time. The effluent overflows and enters the first-stage dissolved air flotation device 5. The water coming into the dissolved air tank is the effluent from the air flotation body, and the gas is compressed air. After pressurization, nanoscale bubbles are released through the dissolved air release device and carried to the surface of the first-stage dissolved air flotation device 5, and are recovered by the slag scraping machine and enter the sludge thickening tank 18;

[0029] The water produced by air flotation enters the air flotation product water tank, and the product water enters the first-stage ultrafiltration membrane 6 through an ultrafiltration feed pump. A security filter is installed at the front end of the first-stage ultrafiltration membrane 6 inlet. Macromolecular organic matter is intercepted by ultrafiltration to ensure the water quality of the reverse osmosis inlet. The backwash water and concentrated water of the first-stage ultrafiltration membrane 6 return to the regulation tank 1;

[0030] In order to control the hardness content of the reverse osmosis inlet water, the ultrafiltration effluent enters the weak acid cation exchanger 7 to adsorb the residual calcium and magnesium ions, and through replacement, the effluent hardness is ensured to be controlled below 10 mg / L;

[0031] The effluent from the weak acid cation exchanger 7 enters the first-stage reverse osmosis membrane 8 through a lift pump. The produced water enters the recycled water tank 20 as high-quality recycled water, and the concentrated water enters the decarbonator. Hydrochloric acid is added to control the pH to 4.5 - 5, converting the alkalinity into carbon dioxide, which is removed by blowing with a blower.

[0032] Since the silicon content is concentrated after the first-stage reverse osmosis, further removal is required to avoid the formation of a large amount of colloidal silicon. The second-stage silicon removal sedimentation tank 21 is used to continue silicon removal. A large amount of suspended solids that are difficult to settle naturally still exist in the effluent, and they are also removed in the form of scum through the second-stage dissolved air flotation device 10.

[0033] The function of the second-stage ultrafiltration membrane 11 is the same as that of the first-stage ultrafiltration membrane 6. The produced water of the second-stage ultrafiltration membrane 11 enters the second-stage reverse osmosis membrane 12, and the produced water enters the pure water reverse osmosis. The chloride ions and sulfate ions in the concentrated water of the second-stage reverse osmosis membrane 12 are concentrated and enter the first-stage nanofiltration for salt separation. The produced water of the first-stage nanofiltration is mainly sodium chloride solution, which enters the evaporation system to produce sodium chloride crystal salt. The concentrated water enters the second-stage nanofiltration membrane 15 to continue concentration and salt separation. The COD in the concentrated water is concentrated. To avoid the influence of high-concentration organic matter on the heat exchange efficiency of the evaporation system and the quality of the product salt, the concentrated water of the second-stage nanofiltration membrane 15 enters the catalytic oxidation device 16 to degrade the organic matter, and the effluent undergoes freezing concentration and melting evaporation to obtain high-quality sodium sulfate crystal salt.

[0034] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Photovoltaic industry high-salinity wastewater treatment system, characterized by: It includes a concentrated brine inlet pipe, a regulating tank, a first-level silicon removal sedimentation tank, a hardness removal sedimentation tank, a first-level dissolved air flotation device, a first-level ultrafiltration membrane, a weak acid cation bed, a first-level reverse osmosis membrane, a decarbonizer, a second-level silicon removal sedimentation tank, a second-level dissolved air flotation device, a second-level ultrafiltration membrane, a second-level reverse osmosis membrane, a first-level nanofiltration membrane, a second-level nanofiltration membrane, and a catalytic oxidation device; The inlet of the regulating tank is connected to the concentrated brine inlet pipe, the outlet of the regulating tank is connected to the inlet pipeline of the primary desiliconization sedimentation tank, the outlet of the primary desiliconization sedimentation tank is connected to the inlet pipeline of the hardness removal sedimentation tank, the outlet of the hardness removal sedimentation tank is connected to the inlet pipeline of the primary dissolved air flotation device, the outlet of the primary dissolved air flotation device is connected to the inlet pipeline of the primary ultrafiltration membrane, the outlet of the primary ultrafiltration membrane is connected to the inlet pipeline of the weak acid cation bed, the outlet of the weak acid cation bed is connected to the inlet pipeline of the primary reverse osmosis membrane, the concentrated water outlet of the primary reverse osmosis membrane is connected to the inlet pipeline of the decarbonizer, and the product water outlet of the decarbonizer is connected to the inlet pipeline of the secondary desiliconization sedimentation tank. The outlet of the secondary silicon removal sedimentation tank is connected to the inlet pipeline of the secondary dissolved air flotation device, the outlet of the secondary dissolved air flotation device is connected to the inlet pipeline of the secondary ultrafiltration membrane, the outlet of the secondary ultrafiltration membrane is connected to the inlet pipeline of the secondary reverse osmosis membrane, the concentrate outlet of the secondary reverse osmosis membrane is connected to the inlet pipeline of the primary nanofiltration membrane, the produced water outlet of the primary nanofiltration membrane is connected to the inlet pipeline of the storage tank of the sodium chloride evaporation system, the concentrate outlet of the primary nanofiltration membrane is connected to the inlet pipeline of the secondary nanofiltration membrane, the concentrate outlet of the secondary nanofiltration membrane is connected to the inlet pipeline of the catalytic oxidation device, and the outlet of the catalytic oxidation device is connected to the inlet pipeline of the storage tank of the sodium sulfate evaporation system.

2. The photovoltaic industry high-salinity wastewater treatment system according to claim 1 is characterized in that: It also includes a sludge thickening tank, and the sludge outlet of the first-level silicon removal sedimentation tank, the sludge outlet of the hardness removal sedimentation tank, the sludge outlet of the first-level dissolved air flotation device, the sludge outlet of the second-level dissolved air flotation device, and the sludge outlet of the second-level silicon removal sedimentation tank are respectively connected to the inlet pipeline of the sludge thickening tank, and the filtrate outlet of the sludge thickening tank is connected to the inlet pipeline of the regulating tank.

3. The photovoltaic industry high-salinity wastewater treatment system according to claim 2 is characterized in that: The concentrated water outlet of the primary ultrafiltration membrane is connected to the inlet pipeline of the regulating tank.

4. The photovoltaic industry high-salinity wastewater treatment system according to claim 3 is characterized in that: The water output outlet of the secondary reverse osmosis is connected to the inlet pipeline of the pure water reverse osmosis membrane, the water output outlet of the pure water reverse osmosis membrane is connected to the inlet pipeline of the reuse water pool, and the concentrated water outlet of the pure water reverse osmosis membrane is connected to the inlet pipeline of the primary reverse osmosis membrane.

5. The photovoltaic industry high-salinity wastewater treatment system according to claim 4 is characterized in that: The water output outlet of the primary reverse osmosis membrane is connected to the inlet pipeline of the reuse water pool.

6. The photovoltaic industry high-salinity wastewater treatment system according to claim 5 is characterized in that: The water production outlet of the secondary nanofiltration membrane is connected to the inlet pipeline of the primary nanofiltration membrane.

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