Zero-discharge treatment system for high-salt organic wastewater

Abstract

The invention discloses a high-salt organic wastewater zero-discharge treatment system, which relates to the technical field of wastewater treatment, and comprises an efficient sedimentation tank, a filter, an ultrafiltration device, a resin softening device, a first reverse osmosis device, a resin adsorption device, a nanofiltration device, a second reverse osmosis device, a bipolar membrane device, a first ozone oxidation device and a sodium sulfate evaporative crystallization device, a second inlet of the filter is communicated with a supernatant outlet of a settling zone of the efficient settling pond, the ultrafiltration device, the resin softening device, the first reverse osmosis device, the resin adsorption device, the nanofiltration device, the second reverse osmosis device and the bipolar membrane device are sequentially arranged, and a tenth inlet of the first ozone oxidation device is communicated with a second concentrated water outlet of the nanofiltration device; an eleventh inlet of the sodium sulfate evaporative crystallization device is communicated with a third produced water outlet of the first ozone oxidation device. The industrial sodium sulfate product, acid and alkali are finally formed, and the whole system is free of other byproducts.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a zero-discharge treatment system for high-salt organic wastewater. Background Technology

[0002] The research and practical application of zero-discharge treatment for high-salt organic wastewater is challenging, mainly because the wastewater has a complex composition and high salt content, placing high demands on zero-discharge technology. On the other hand, some steel plants have already implemented related projects, but the investment and operating costs are high, and the sodium chloride produced by evaporation and crystallization has poor market demand.

[0003] Therefore, there is an urgent need for a more competitive process technology for zero-discharge treatment of high-salt organic wastewater that is low in energy consumption and low in cost. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a zero-discharge treatment system for high-salt organic wastewater.

[0005] This application provides a zero-discharge treatment system for high-salinity organic wastewater, including a high-efficiency sedimentation tank, a filter, an ultrafiltration device, a resin softening device, a first reverse osmosis device, a resin adsorption device, a nanofiltration device, a second reverse osmosis device, a bipolar membrane device, a first ozone oxidation device, and a sodium sulfate evaporation and crystallization device. The high-efficiency sedimentation tank has a first inlet and a supernatant outlet in the sedimentation zone. The first inlet is used to receive the high-salinity organic wastewater to be treated. The filter has a second inlet and a first filter outlet, with the second inlet connected to the supernatant outlet in the sedimentation zone. The ultrafiltration device has a third inlet and a second filter outlet, with the third inlet connected to the first filter outlet. The resin softening device has a fourth inlet and a softening outlet, with the fourth inlet connected to the second filter outlet. The first reverse osmosis device has a fifth inlet and a first concentrate outlet, with the fifth inlet connected to the softening outlet. The resin adsorption device contains components for adsorbing organic pollutants in the wastewater. The granular resin adsorption device has a sixth inlet and a first product water outlet, with the sixth inlet connected to the first concentrated water outlet. The nanofiltration device has a nanofiltration membrane that allows monovalent ions to pass through while blocking divalent ions. The nanofiltration device has a seventh inlet, a second product water outlet, and a second concentrated water outlet, with the seventh inlet connected to the first product water outlet. The second reverse osmosis device has an eighth inlet and a third concentrated water outlet, with the eighth inlet connected to the second product water outlet. The bipolar membrane device has a ninth inlet, an acid outlet, and an alkali outlet, with the ninth inlet connected to the third concentrated water outlet. The acid outlet and alkali outlet output acid products and alkali products, respectively. The first ozone oxidation device has a tenth inlet and a third product water outlet, with the tenth inlet connected to the second concentrated water outlet. The sodium sulfate evaporation and crystallization device has an eleventh inlet and a sodium sulfate outlet, with the eleventh inlet connected to the third product water outlet. The sodium sulfate outlet is used to output industrial sodium sulfate crystals.

[0006] In some embodiments, the filter is a multi-media filter, in which multiple filter media are compacted and arranged in a bottom-up order within the filter cylinder, and the particle size of the multiple filter media increases sequentially from bottom to top.

[0007] In some embodiments, the resin adsorption device is provided with a cleaning channel for passing through particulate resin. The cleaning channel forms a cleaning liquid inlet and a cleaning liquid outlet in the resin adsorption device. The resin adsorption device is equipped with a regeneration device. The regeneration device is provided with an output port for conveying regenerated liquid. The output port is connected to the cleaning liquid inlet. The cleaning liquid outlet is used to discharge the regenerated waste liquid after cleaning.

[0008] In some embodiments, the resin adsorption device is further equipped with a second ozone oxidation device, which has a regeneration waste liquid receiving port connected to the cleaning liquid outlet, and the product water outlet of the second ozone oxidation device is connected to the plant's wastewater treatment system.

[0009] In some implementations, the high-efficiency sedimentation tank is equipped with a sedimentation zone sludge outlet, which is connected to the plant's sludge treatment system.

[0010] In some embodiments, the filter, ultrafiltration unit, and first reverse osmosis unit are each equipped with a backwashing mechanism.

[0011] In some implementations, the filter, ultrafiltration unit, and first reverse osmosis unit are each provided with a backwash water outlet, which is connected to the plant's wastewater treatment system.

[0012] In some embodiments, the first reverse osmosis unit, the second reverse osmosis unit, and the bipolar membrane unit are each provided with a product water outlet, which is connected to a product water tank.

[0013] In some embodiments, the sodium sulfate evaporation and crystallization apparatus is provided with a condensate outlet, which is connected to a product water tank.

[0014] In some embodiments, the bipolar membrane device is equipped with an acid tank and an alkali tank, which are connected to the acid outlet and the alkali outlet, respectively.

[0015] The beneficial effects of this application are as follows: Hardness in wastewater is reduced through high-efficiency sedimentation and resin softening; organic pollutants in wastewater are removed through resin adsorption and ozone oxidation, reducing membrane system fouling; monovalent and divalent salts are separated by nanofiltration; the divalent salt is ultimately evaporated and crystallized to form industrial sodium sulfate; and the monovalent salt is passed through a bipolar membrane to form acid and alkali, allowing for water reuse. The entire system produces no other byproducts, solving the problems of high costs and low value of sodium chloride caused by the evaporation and crystallization of all wastewater in traditional processes. This application features a simple process, reducing investment and operating costs, and achieving zero discharge of high-salt organic wastewater. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention.

[0017] Figure 1 This is a schematic block diagram of a zero-discharge treatment system for high-salt organic wastewater provided in this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] Furthermore, reference numerals and / or reference letters may be repeated in different examples in this application. Such repetition is for simplification and clarity purposes and does not in itself indicate a relationship between the various embodiments and / or settings discussed. In addition, this application provides examples of various specific processes and materials; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0020] This application provides a zero-discharge treatment system for high-salt organic wastewater, hereinafter referred to as "this system". Please refer to [the system description]. Figure 1 This system includes a high-efficiency sedimentation tank, a filter, an ultrafiltration device, a resin softening device, a first reverse osmosis device, a resin adsorption device, a nanofiltration device, a second reverse osmosis device, a bipolar membrane device, a first ozone oxidation device, and a sodium sulfate evaporation and crystallization device.

[0021] The high-efficiency sedimentation tank has a first inlet and a supernatant outlet for the sedimentation zone. The first inlet receives the high-salt organic wastewater to be treated, and the supernatant outlet for the sedimentation zone discharges the supernatant from the sedimentation zone. Also known as a high-density sedimentation tank, the high-efficiency sedimentation tank is a highly efficient solid-liquid separation technology. Its core process typically consists of a coagulation zone, a flocculation zone, and a sedimentation zone. These three zones gradually remove suspended particles from the water through chemical and physical processes. The sedimentation zone is the core area for solid-liquid separation. Water carrying large flocs settles here due to gravity, and the supernatant is discharged from the supernatant outlet. In this application, the main function of the high-efficiency sedimentation tank is to remove calcium and magnesium, fluoride, and suspended solids to protect the subsequent oxidation and membrane systems. For some embodiments, please refer to... Figure 1 In some implementations, the high-efficiency sedimentation tank is equipped with a sedimentation zone sludge outlet, which is connected to the plant's sludge treatment system.

[0022] Please refer to Figure 1 In this system, the filter is installed after the high-efficiency sedimentation tank. The filter has a second inlet and a first outlet, with the second inlet connected to the supernatant outlet of the sedimentation zone in the high-efficiency sedimentation tank. The filter's function is to remove suspended solids, colloidal substances, and certain harmful substances from seawater through the interception and filtration of the filter media. In some embodiments, the filter is a multi-media filter. Multiple filter media are compacted and arranged in a bottom-up order within the filter cylinder, with the particle size increasing sequentially from bottom to top. During operation, the liquid flows downwards along the filter, and the filtration rate of the multi-media filter can reach 10m / h-12m / h, meeting the requirements of actual production conditions. The filter generally requires a backwashing mechanism. In some embodiments, backwashing is performed when the pressure difference between the inlet and outlet reaches a certain value or the operating time reaches a certain value. The filter has a backwash water outlet connected to the plant's wastewater treatment system.

[0023] Please refer to Figure 1 In terms of process sequence, the ultrafiltration unit is located after the filter. The ultrafiltration unit has a third inlet and a second outlet, with the third inlet connected to the first outlet of the filter. In this system, the ultrafiltration unit removes suspended solids, colloids, bacteria, etc., from the water, serving as pretreatment protection for the subsequent reverse osmosis membrane system. The ultrafiltration unit generally requires a backwashing mechanism. In some embodiments, routine backwashing and chemical cleaning are performed after a certain period of operation. Correspondingly, the ultrafiltration unit has a backwash water outlet connected to the plant's wastewater treatment system. In some embodiments, a self-cleaning filter is installed in the area before the fluid enters the ultrafiltration membrane. This self-cleaning filter intercepts larger suspended solids or fine sand particles to ensure the safe operation of the ultrafiltration unit.

[0024] Please refer to Figure 1 In terms of process sequence, the resin softening unit is located after the ultrafiltration unit. The resin softening unit has a fourth inlet and a softening outlet. The fourth inlet is connected to the second filter outlet of the ultrafiltration unit. The core principle of resin softening is ion exchange, which removes calcium and magnesium ions from the water using specialized resin, thereby reducing water hardness.

[0025] Please refer to Figure 1In terms of process sequence, the first reverse osmosis unit is located after the resin softening unit. The first reverse osmosis unit has a fifth inlet and a first concentrate outlet, which are connected to the softening outlet of the resin softening unit. In this system, the first reverse osmosis unit can remove most of the salt and large molecular organic matter from the water. The reverse osmosis concentrate enters the resin adsorption unit. The first reverse osmosis unit has a product water outlet, which is connected to a product water tank. The reverse osmosis product water can be reused in the product water tank. The reverse osmosis unit requires periodic backwashing. The first reverse osmosis unit is generally equipped with a backwashing mechanism. Each first reverse osmosis unit has a backwash water outlet, which is connected to the plant's wastewater treatment system. The backwash wastewater is neutralized and then discharged into the plant's wastewater treatment system.

[0026] Please refer to Figure 1 In terms of process sequence, the resin adsorption device is set after the first reverse osmosis device. The resin adsorption device contains granular resin, which adsorbs organic pollutants in the wastewater. The resin adsorption device has a sixth inlet and a first product water outlet. The sixth inlet is connected to the first concentrated water outlet of the first reverse osmosis device. The product water after the removal of organic matter enters the nanofiltration device through the pipeline from the first product water outlet.

[0027] Please refer to Figure 1 In terms of process sequence, the nanofiltration unit is located after the resin adsorption unit. The nanofiltration unit is equipped with a nanofiltration membrane that allows monovalent ions to pass through while blocking divalent ions, thus separating monovalent and divalent salts in the wastewater. The nanofiltration unit has a seventh inlet, a second product water outlet, and a second concentrate outlet. The seventh inlet is connected to the first product water outlet of the resin adsorption unit. The nanofiltration product water enters the second reverse osmosis unit from the second product water outlet, and the nanofiltration concentrate enters the first ozone oxidation unit from the second concentrate outlet.

[0028] Please refer to Figure 1 The second reverse osmosis unit has an eighth inlet and a third concentrate outlet. The eighth wellhead is connected to the second product water outlet of the nanofiltration unit. In this system, the second reverse osmosis unit can remove most of the pollutants from the wastewater. The concentrate from the second reverse osmosis unit enters the next bipolar membrane unit. The second reverse osmosis unit has a product water outlet, which is connected to the product water tank. The product water from the second reverse osmosis unit enters the product water tank for reuse.

[0029] The bipolar membrane device has a ninth inlet, an acid outlet, and an alkali outlet. The ninth inlet is connected to the third concentrate outlet of the second reverse osmosis unit. The bipolar membrane device contains anion exchange membranes, cation exchange membranes, and a bipolar membrane. Under the action of an electric current, it converts the salts in the wastewater into acids and alkalis, which are then output from the acid outlet and alkali outlet, respectively. In some embodiments, please refer to... Figure 1 The bipolar membrane device is equipped with acid and alkali tanks, which are connected to the acid outlet and alkali outlet, respectively. The acid and alkali entering the tanks can be reused within the plant area. For some implementation methods, please refer to... Figure 1 The bipolar membrane device is equipped with a product water outlet, which is connected to the product water tank. The product water from the bipolar membrane device enters the product water tank for later use.

[0030] Please refer to Figure 1 The first ozone oxidation unit is equipped with a tenth inlet and a third product water outlet. The tenth inlet is connected to the second concentrate outlet of the nanofiltration unit. The nanofiltration concentrate from the nanofiltration unit enters the first ozone oxidation unit, where ozone oxidation is used to remove organic pollutants from the concentrate.

[0031] Please refer to Figure 1 The sodium sulfate evaporation and crystallization unit has an eleventh inlet and a sodium sulfate outlet. The eleventh inlet is connected to the third product water outlet of the first ozone oxidation unit. The wastewater from the first ozone oxidation unit enters the sodium sulfate evaporation and crystallization unit, where it is evaporated to form industrial sodium sulfate crystals. The industrial sodium sulfate crystals are output from the sodium sulfate outlet and can be sold externally, showing a significantly better market prospect than sodium chloride. In some embodiments, when treating sodium sulfate-containing wastewater, the sodium sulfate evaporation crystallization device produces product water, which is condensate. The sodium sulfate evaporation crystallization device is equipped with a condensate outlet, which is connected to the product water tank.

[0032] In some embodiments, the resin adsorption device is provided with a cleaning channel for passing through the particulate resin. The cleaning channel has a cleaning liquid inlet and a cleaning liquid outlet in the resin adsorption device. Please refer to [reference needed]. Figure 1 The resin adsorption device is equipped with a regeneration unit, which has an output port for conveying regenerated liquid. The output port of the regeneration unit is connected to the inlet of the cleaning liquid. The regeneration unit provides regenerated liquid to the resin adsorption device so that the granular resin can be eluted after adsorption saturation. The regenerated waste liquid after cleaning is discharged from the cleaning liquid outlet. In some embodiments, the resin adsorption device is also equipped with a second ozone oxidation unit. The regenerated waste liquid after cleaning is discharged to the second ozone oxidation unit, which has a regenerated waste liquid receiving port connected to the cleaning liquid outlet. The product water outlet of the second ozone oxidation unit is connected to the plant's wastewater treatment system, where the regenerated waste liquid is ozone-oxidized before being discharged to the plant's wastewater treatment system for further treatment.

[0033] Based on practical considerations, the inventors controlled the coagulation reaction time in the mixing zone of the high-efficiency sedimentation tank to 2-3 minutes, the treatment time in the flocculation zone to 15-20 minutes, and the surface load in the sedimentation zone to 8 m². 3 / (m 2 .h)-12m 3 / (m 2 .h).

[0034] In summary, this application reduces the hardness of wastewater through high-efficiency sedimentation and resin softening, removes organic pollutants from the wastewater through resin adsorption and ozone oxidation, reduces membrane system fouling, separates monovalent and divalent salts through nanofiltration, and finally, the divalent salt is evaporated and crystallized to form industrial sodium sulfate, while the monovalent salt is passed through a bipolar membrane to form acid and alkali, allowing the treated water to be reused. The entire system produces no other byproducts, solving the problems of high cost and low value of sodium chloride caused by the evaporation and crystallization of all wastewater in traditional processes. Furthermore, this system has a simple and efficient process, reducing the investment and operating costs of related equipment. Overall, this application achieves zero discharge of high-salinity organic wastewater.

[0035] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0037] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A zero-discharge treatment system for high-salt organic wastewater, characterized in that, include: The high-efficiency sedimentation tank is equipped with a first inlet and a supernatant outlet in the sedimentation zone. The first inlet is used to receive high-salt organic wastewater to be treated. The filter is provided with a second inlet and a first outlet, the second inlet being connected to the supernatant outlet of the sedimentation zone; The ultrafiltration device is provided with a third inlet and a second filter outlet, wherein the third inlet is connected to the first filter outlet; The resin softening device is provided with a fourth inlet and a softening outlet, wherein the fourth inlet and the second filter outlet are connected; The first reverse osmosis unit is provided with a fifth inlet and a first concentrate outlet, wherein the fifth inlet and the softening outlet are connected. A resin adsorption device is provided with granular resin for adsorbing organic pollutants in wastewater. The resin adsorption device is provided with a sixth inlet and a first product water outlet. The sixth inlet is connected to the first concentrated water outlet. A nanofiltration device is provided with a nanofiltration membrane that allows monovalent ions to pass through while blocking divalent ions. The nanofiltration device is provided with a seventh inlet, a second product water outlet, and a second concentrate outlet. The seventh inlet and the first product water outlet are connected. The second reverse osmosis unit is equipped with an eighth inlet and a third concentrate outlet, and the eighth wellhead is connected to the second product water outlet; The bipolar membrane device is equipped with a ninth inlet, an acid outlet, and an alkali outlet. The ninth inlet is connected to the third concentrate outlet, and the acid outlet and alkali outlet output acid product and alkali product, respectively. The first ozone oxidation device is equipped with a tenth inlet and a third product water outlet, wherein the tenth inlet and the second concentrate outlet are connected; and The sodium sulfate evaporation and crystallization device has an eleventh inlet and a sodium sulfate outlet. The eleventh inlet is connected to the third product water outlet, and the sodium sulfate outlet is used to output industrial sodium sulfate crystals.

2. The zero-discharge treatment system for high-salt organic wastewater as described in claim 1, characterized in that, The filter is a multi-media filter, in which multiple filter media are compacted and arranged in a bottom-up order within the filter cylinder, and the particle size of the multiple filter media increases sequentially from bottom to top.

3. The zero-discharge treatment system for high-salt organic wastewater as described in claim 1, characterized in that, The resin adsorption device is provided with a cleaning channel through which the granular resin passes. The cleaning channel forms a cleaning liquid inlet and a cleaning liquid outlet in the resin adsorption device. The resin adsorption device is equipped with a regeneration device. The regeneration device is provided with an output port for conveying regeneration liquid. The output port is connected to the cleaning liquid inlet. The cleaning liquid outlet is used to discharge the regeneration waste liquid after cleaning.

4. The zero-discharge treatment system for high-salt organic wastewater as described in claim 3, characterized in that, The resin adsorption device is also equipped with a second ozone oxidation device. The second ozone oxidation device is provided with a regeneration waste liquid receiving port, which is connected to the cleaning liquid outlet. The product water outlet of the second ozone oxidation device is connected to the plant's wastewater treatment system.

5. The zero-discharge treatment system for high-salt organic wastewater as described in claim 1, characterized in that, The high-efficiency sedimentation tank is equipped with a sedimentation zone sludge outlet, which is connected to the plant's sludge treatment system.

6. The zero-discharge treatment system for high-salt organic wastewater as described in claim 1, characterized in that, The filter, the ultrafiltration device, and the first reverse osmosis device are each equipped with a backwashing mechanism.

7. The zero-discharge treatment system for high-salt organic wastewater as described in claim 6, characterized in that, The filter, the ultrafiltration device, and the first reverse osmosis device are each provided with a backwash water outlet, which is connected to the plant's wastewater treatment system.

8. The zero-discharge treatment system for high-salt organic wastewater as described in claim 1, characterized in that, The first reverse osmosis device, the second reverse osmosis device, and the bipolar membrane device are each provided with a product water outlet, and the product water outlet is connected to the product water tank.

9. The zero-discharge treatment system for high-salt organic wastewater as described in claim 1, characterized in that, The sodium sulfate evaporation and crystallization device is equipped with a condensate outlet, which is connected to the product water tank.

10. The zero-discharge treatment system for high-salinity organic wastewater as described in claim 1, characterized in that, The bipolar membrane device is equipped with an acid tank and an alkali tank, which are respectively connected to the acid outlet and the alkali outlet.

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