CN117735786A

CN117735786A - Fluoride industry washing wastewater desalination and resource utilization device and method

Info

Publication number: CN117735786A
Application number: CN202410087519.1A
Authority: CN
Inventors: 李天玉; 张颖; 张杨; 韩兴亮; 贾泽清; 孙璐; 任凤伟; 陈亦力; 罗艳
Original assignee: Beijing Huateyuan Technology Co ltd
Current assignee: Beijing Huateyuan Technology Co ltd
Priority date: 2024-01-22
Filing date: 2024-01-22
Publication date: 2024-03-22

Abstract

A fluoride wash wastewater desalination resource utilization device and a fluoride wash wastewater desalination resource utilization method, which belong to the technical field of sewage treatment. The method comprises the following steps: a pretreatment section step, a biochemical pretreatment section step, a membrane pretreatment section step, a reverse osmosis RO-EDI-EDR advanced treatment section step. The pretreatment needed by the invention is simple, the pretreatment is usually met by multi-medium filtration, the COD in the concentrated water is not increased, the discharge and the use of the concentrated water are not affected, the method has higher water recovery rate, less concentrated water discharge amount, high recycling degree, higher capability of resisting organic matter pollution, difficult scaling and difficult pollution by organic matters, no scale inhibitor is needed, the operation cost is lower, and free chlorine is tolerated.

Description

Fluoride industry washing wastewater desalination and resource utilization device and method

Technical Field

The invention relates to a fluoride washing wastewater desalination resource utilization device and method, and belongs to the technical field of sewage treatment.

Background

Fluorine pollution is an important pollution form in the chemical industry, and with the expansion of industrial production scale, the production amount of fluoride wastewater is increased. In recent years, the development speed of the fluoride industry in China is extremely high, the speed of the whole fluoride industry market is kept to be about 20%, and the fluoride industry in the chemical industry field is expected to be developed rapidly. The domestic fluoropolymer chemical products mainly adopt varieties such as polytetrafluoroethylene and the like, and the yields of varieties such as vinylidene fluoride, hexafluoropropylene, poly (perfluoroethylene) and the like are small and are mostly in the production stage. In the context of increased demand, the fluoride product inlet rate remains high.

From the point of view of the fluoride production process, a large amount of fluorine-containing wastewater is generated in the production process of the product, and the wastewater is extremely easy to cause pollution to soil, water and vegetation. The fluorine chemical industry has wide development prospect as a new chemical material industry. Under the situation of considering both economic development and environmental protection of the current society, the technology for treating the fluoride wastewater is continuously improved, and the development of the whole wastewater treatment industry level is promoted.

The fluoride wastewater mainly has the characteristics of high salinity, strong biotoxicity and poor biochemistry. The focus of fluoride wastewater treatment is inorganic fluoride ions and organic fluorides. Among these, organofluorine contaminants are very stable in nature and poor in biodegradability, mainly due to the strong accessibility of the C-F bonds in organofluorine compounds and the large bond energy (bond energy of about 460 kJ/mol). While traditional biological sewage treatment processes have low efficiency in treating organic fluorine wastewater, some advanced oxidation processes developed in recent years have high treatment cost.

The traditional process is generally treated by pretreatment softening and hardness removal, reverse osmosis concentration desalination or reverse osmosis, chemical softening, resin softening and other processes. In the general process, only a part of treatment functions are considered, so that the problems of unqualified running water quality in the later stage of chemical wastewater treatment, low treatment efficiency of resin used before and after a membrane system or chemical softening treatment, high replacement cost of the used resin and the like are caused.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a desalination and resource utilization device and method for fluoride industry washing wastewater.

A fluoride wash wastewater desalination resource utilization method comprises the following steps: a pretreatment section step, a biochemical pretreatment section step, a membrane pretreatment section step, a reverse osmosis RO-EDI-EDR advanced treatment section step.

The desalination and recycling method for the fluoride wash wastewater also comprises the following steps:

pretreatment section step: precipitating inorganic fluoride ions and suspended matters by using a high-density sedimentation tank, performing preliminary filtration and preliminary biochemical degradation by using a biological aerated filter, further removing soluble matters and surface active matters by using an air floatation tank, degrading organic fluorine by using ozone catalytic oxidation of effluent, reducing biological toxic matters, removing organic matters and suspended matters by using the effluent after entering an aerobic MBR, and performing final trace removal of suspended matters and organic matters by using multi-medium filtration and active carbon filtration before entering a membrane system, thereby ensuring the water quality of membrane-entering sewage; concentrating by UF+RO double membrane method, desalting by EDR, and increasing water yield.

Biochemical pretreatment section step: removing large-particle-size suspended matters in fluoride washing wastewater by using a high-density pool, and adding CaCO (CaCO) ₃ With Ca (OH) ₂ The precipitation of inorganic fluoride ions is enhanced by a double-alkali method, partial sludge is refluxed by a sludge reflux pump of a high-density tank, the sedimentation effect of suspended matters is enhanced, the consumption of flocculant is reduced, effluent from the high-density tank enters an aeration biological filter tank, the small-particle-size suspended matters are intercepted by the biochemical flocculation effect of microorganisms in the filter tank, and organic matters which are easy to degrade in washing wastewater are treated, primary filtered effluent enters an air-dissolving floatation tank to remove the small-particle-size suspended matters in the sewage and the soluble organic matters such as surfactants in the washing wastewater by a high-efficiency air-dissolving floatation device, the air-floating effluent enters an ozone catalytic oxidation filter tank to degrade the organic fluoride by using a proper OC proportion, the organic fluoride is degraded into organic matters which are easy to degrade, effluent enters an aerobic MBR tank to degrade by aerobic bacteria in the aerobic tank, the filtration effect of an MBR membrane is ensured, the fluorine ion content in the effluent is greatly reduced, the solid suspended matters and the soluble organic matter content is greatly reduced, and the biochemical pretreatment effect is completed.

Membrane pretreatment stage: the pretreated sewage is subjected to secondary filtration through a multi-medium filter and an activated carbon filter, so that the sewage before membrane feeding does not contain suspended matters with small particle size, and the ultrafiltration treatment ensures that the effluent meets lower requirements of reverse osmosis turbidity less than 1NTU and SDI less than 5 and does not cause scaling risk to subsequent concentration.

Reverse osmosis RO-EDI-EDR advanced treatment stage: the reverse osmosis RO uses a two-stage desalting system to carry out preliminary desalting treatment, reverse osmosis produced water enters an EDI system to carry out deep desalting, reverse osmosis concentrated water enters the EDR system to carry out concentration again, produced water flows back to an ozone catalytic oxidation section to carry out treatment, and the concentrated water is discharged to achieve the maximum produced water recovery effect.

A fluoride wash wastewater desalination resource utilization method comprises the following steps:

biochemical pretreatment section step: the high-density pool is utilized to remove large-particle-size suspended matters and inorganic fluorine ions, the aeration biological filter pool is utilized to remove small-particle-size suspended matters and easily degradable organic matters, the dissolved air flotation pool is utilized to remove small-particle-size suspended matters and surface active agents, the ozone catalytic oxidation filter pool is utilized to degrade organic fluoride to break biological toxicity, and the aerobic MBR pool is utilized to degrade organic matters to achieve better removal effect of suspended matters, biological toxic matters and surface active matters in fluorine chemical wastewater.

Membrane pretreatment stage: the SDI and turbidity are reduced through multistage filtration and ultrafiltration, the purpose of slowing down membrane pollution is achieved, RO reverse osmosis-EDI is finally utilized for concentration and desalination, EDR is used for concentration again, and the water yield is improved.

Pretreatment section step: the concentration efficiency of the subsequent desalination section is ensured by sequentially removing large-particle-size suspended matters, soluble surface active substances, biological toxic substances, soluble organic substances and SDI, the desalination rate is improved by utilizing RO-EDI in the concentration section, the water yield is improved by utilizing EDR to treat concentrated water, and the desalination recycling treatment effect of the fluoride washing wastewater is achieved.

Compared with RO, the invention has the following advantages:

(1) The required pretreatment is simple and is usually satisfied by multi-media filtration.

(2) COD in the concentrated water is not increased, and the discharge and the use of the concentrated water are not affected.

(3) Has higher water recovery rate, less concentrated water discharge and high recycling degree.

(4) The equipment is frequently reversed, so that higher capability of resisting organic matter pollution is brought, scaling is not easy to occur, and the equipment is not easy to be polluted by the organic matter.

(5) No scale inhibitor is needed, and the operation cost is lower.

(6) Free chlorine is tolerated.

According to the water quality characteristics of the invention, if the system is replaced by the first-stage RO-3 and the first-stage RO-4 instead of the ED device, if 80 percent recovery rate which is the same as ED is required, the recovery rates of the first-stage RO-3 and the first-stage RO-4 are 66.02 percent and 67.97 percent respectively, the recovery rates of two sections of reverse osmosis are not high, and meanwhile, if two sections of reverse osmosis are selected, the concentrated water discharged from the outside of the first-stage RO-4 is 4.04m ³ And/h, and the external drainage rate of ED is 2.94m ³ The ratio of the water to the discharged water is larger than/h, the requirement on the discharged water amount in the bidding document is less than or equal to 5 percent, the discharged water conductivity of the other two sections of RO is 6901.07, the concentration is not high, and the discharged water conductivity of ED is 9152.36.

If two-stage reverse osmosis is adopted to replace ED, the COD after concentration is about 200 when entering the first-stage RO-4, and the COD does not meet the water inlet condition.

In conclusion, compared with reverse osmosis, the electrodialysis device has the advantages that the concentration degree of the electrodialysis device on inorganic salt is higher, the device is simpler, no scale inhibitor is needed to be added, and the electrodialysis device is better in combination with the actual situation of the invention.

The design coefficient is 1.15 in combination with the water quality condition and the treatment requirement of the invention; the biochemical pretreatment process adopts a high-density sedimentation tank to remove suspended matters and turbidity; the biological filtration treatment stage adopts an aeration biological filter, an air floatation tank, an ozone catalytic oxidation, an aerobic tank and an MBR membrane tank, COD can be effectively removed in the whole biochemical stage, and the water quality of the inlet water of the later-stage membrane process and the water quality of the outlet water of the whole process are ensured to reach the standard;

the membrane pretreatment process adopts a multi-stage filter, and MBR produced water is subjected to multi-stage filtration, and comprises a multi-medium filter, an activated carbon filter and ultrafiltration to remove suspended matters, turbidity and SDI in the treated water, so that the running stability of the RO membrane process is ensured, and the membrane pollution is reduced. The advanced treatment system adopts a mature reverse osmosis system, the primary RO produced water is further desalted, and enters a secondary RO system to carry out desalination treatment again, and the desalination rate of the two-stage RO desalination system reaches 99.75%;

And after the RO system, an EDI system is adopted, the RO produced water is subjected to deep desalination treatment, the resistivity of the produced water of the system is more than 16MΩ, and the overall produced water recovery rate is 95.92%.

And the recovery rate of the system is improved, RO concentrated water is concentrated again, an EDR system is adopted, the first-stage RO concentrated water and the second-stage RO concentrated water pass through the EDR system, the produced water is recovered to an ozone catalytic oxidation system, the recovery rate of the whole produced water is improved, the final discharge amount of the waste brine is 2.95m < 3 >/h, and the discharge rate of the waste brine is 3.28%.

Drawings

The invention, together with a further understanding of the many of its attendant advantages, will be best understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings, which are included to provide a further understanding of the invention, and the accompanying drawings, illustrate and describe the invention and do not constitute a limitation to the invention, and wherein:

fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a schematic plan view of the device of the present invention.

Fig. 3 is a schematic flow chart of the present invention.

FIG. 4 is a schematic diagram of a table of the present invention.

Fig. 5 is a roll reverse osmosis membrane structure.

Fig. 6STRO structure diagram.

Fig. 7DTRO structure diagram.

Detailed Description

The invention will be further described with reference to the drawings and examples.

It will be apparent that many modifications and variations are possible within the scope of the invention, as will be apparent to those skilled in the art based upon the teachings herein.

It will be obvious to those skilled in the art that, as used herein, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element or component is referred to as being "connected" to another element or component, it can be directly connected to the other element or component or intervening elements or components may also be present. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

Unless specifically stated or limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; the connection can be mechanical connection (welding, riveting and bolting) or electric connection; can be directly connected or indirectly connected through an intermediate device, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

It will be understood by those skilled in the art that all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art unless defined otherwise.

In order to facilitate an understanding of the embodiments, a further explanation will be provided in connection with the following, and the respective embodiments do not constitute a limitation of the embodiments of the invention.

Example 1: as shown in fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6 and fig. 7, the desalination and recycling method for the fluoride washing wastewater has the advantages that suspended matters, hardness and biotoxic substances are less treated in a pretreatment section, only a part of treatment functions are considered in the general process, and the quality of running water in the later stage of chemical wastewater treatment is unqualified; the film system uses resin before and after or has low treatment efficiency of chemical softening treatment, and the replacement cost of the used resin is high.

A method for reutilizing fluoride washing wastewater desalination resources includes such steps as high-density sedimentation for depositing inorganic fluoride ions and suspended matters, aerating biological filter for preliminary filtering and preliminary biochemical degradation, air floatation pool for further removing soluble substances and surface active substances, ozone catalytic oxidation for degrading organic fluorine, reducing biotoxic substances, aerobic MBR for removing organic substances and suspended matters, multi-medium filtering and active carbon filtering for removing trace of suspended matters and organic substances, concentrating by UF+RO double membrane method, EDR for desalinating concentrated water, high water yield, EDI for treating water to obtain high water concentration, and better treating effect and economic benefit.

The fluoride industry washing waste water desalination resource utilization device mainly comprises a biochemical pretreatment section, namely a high-density tank, an aeration biological filter, a dissolved air floatation tank, an ozone catalytic oxidation filter, an aerobic MBR tank, a membrane pretreatment section, namely a multi-medium filter, an active carbon filter, ultrafiltration and reverse osmosis RO-EDI-EDR deep treatment.

The utility model provides a fluoride industry washing waste water desalination resource utilization device, biochemical pretreatment structure: the fluoride washing wastewater is connected to a regulating tank 1.0, the water outlet of the regulating tank 1.0 is connected to the water inlet of a high-density sedimentation tank 1.1, the water outlet of the high-density sedimentation tank 1.1 is connected to a biological aerated filter 1.2, the sludge outlet of the high-density sedimentation tank 1.1 is discharged to a sludge storage tank, the water outlet of the biological aerated filter 1.2 is connected to an air floatation tank 1.3, the backwash water outlet of the biological aerated filter 1.2 is discharged to the regulating tank 1.0, the water outlet of the air floatation tank 1.3 is connected to an ozone catalytic oxidation unit 1.4, the scum outlet of the air floatation tank 1.3 is discharged to a sludge storage tank, the water outlet of the ozone catalytic oxidation unit 1.4 is connected to an aerobic MBR membrane tank 1.5, the water outlet of the aerobic MBR membrane tank 1.5 is connected to an intermediate water tank 2.0, the sludge outlet of the aerobic MBR membrane tank 1.5 is discharged to the sludge storage tank, the sludge storage tank is connected to a plate frame dehydrator, the sludge storage tank is connected to the sludge dehydrator, and the filtrate outlet of the plate frame dehydrator is discharged to the regulating tank 1.0.

Fluoride industry washing waste water desalination resource utilization device, membrane pretreatment structure: the water outlet of the middle water tank 2.0 is connected with the multi-medium filter 2.1, the water outlet of the multi-medium filter 2.1 is connected with the activated carbon filter 2.2, the backwash water outlet of the multi-medium filter 2.1 is discharged to the regulating tank 1.0, the water outlet of the activated carbon filter 2.2 is connected with the ultrafiltration 2.3, the backwash water outlet of the activated carbon filter 2.2 is discharged to the regulating tank 1.0, the water outlet of the ultrafiltration 2.3 is connected with the ultrafiltration water producing tank 3.0, the backwash water outlet of the ultrafiltration 2.3 is discharged to the regulating tank 1.0, and the water outlet of the ultrafiltration water producing tank 3.0 is connected with the first-level RO-13.1.

A fluoride wash wastewater desalination and resource utilization device comprises a first-stage RO-1, a first-stage RO-2 and a second-stage RO, wherein RO reverse osmosis 3.1 comprises a first-stage RO-1, a first-stage RO-2 and a second-stage RO. Reverse osmosis RO-EDI-EDR advanced treatment segment structure: the water outlet of the first RO-1 water producing port is connected to the first water producing tank 3.5, the water outlet of the first RO-1 water concentrating port is connected to the water concentrating tank, the water outlet of the water concentrating tank is connected to the first RO-2 water producing tank 3.5, the water outlet of the water concentrating tank 2 is connected to the EDR system 3.3, the water outlet of the EDR system 3.3 is connected to the ozone catalytic oxidation unit 1.4, the EDR system 3.3 is discharged out of concentrated water, the water outlet of the first water producing tank 3.5 is connected to the second RO, the water outlet of the second RO is connected to the second water producing tank 3.6, the water outlet of the second water producing tank 3.6 is connected to the EDI system 3.4, the water outlet of the EDI system 3.4 is connected to the nitrogen seal water tank 3.7, the water outlet of the EDI system 3.4 is connected to the first water producing tank 3.5, and the nitrogen seal water tank 3.7 is connected to the recycling pipeline.

The biochemical pretreatment section structure utilizes a high-density pool to remove large-particle-size suspended matters in the fluoride washing wastewater, and CaCO is added ₃ With Ca (OH) ₂ The double-alkali method enhances the precipitation of inorganic fluoride ions, and utilizes a sludge reflux pump of a high-density tank to reflux part of sludge, thereby enhancing the sedimentation effect of suspended matters and reducing the use amount of flocculant. The effluent from the high-density tank enters a biological aerated filter to intercept suspended matters with small particle size by using the biochemical flocculation effect of microorganisms in the filter and treat easily degradable organic matters in the washing wastewater, the primary filtered effluent enters a dissolved air floatation tank to remove suspended matters with small particle size in the sewage and soluble organic matters such as surfactant in the washing wastewater by using a high-efficiency dissolved air floatation device, the air floatation effluent enters an ozone catalytic oxidation filter to degrade the organic fluoride by using a proper OC ratio, And (3) degrading organic fluoride into easily degradable organic matters, enabling effluent to enter the aerobic MBR tank, degrading aerobic bacteria in the aerobic tank, and ensuring the filtering effect of the MBR membrane, so that the content of fluoride ions in the effluent is greatly reduced, the content of solid suspended matters and soluble organic matters is greatly reduced, and the biochemical pretreatment effect is finished.

The effluent quality of the pretreated membrane pretreatment section structure is good, the secondary filtration is carried out through the multi-medium filter and the activated carbon filter, the sewage before membrane feeding is ensured not to contain suspended matters with small particle size, the requirement that the effluent meets the reverse osmosis turbidity of less than 1NTU and SDI of less than 5 is ensured to be lower after ultrafiltration treatment, and the scaling risk is not caused to the subsequent concentration.

Reverse osmosis RO-EDI-EDR advanced treatment section structure, reverse osmosis RO uses two-stage desalination system to carry out preliminary desalination, and reverse osmosis produces water and gets into EDI system and carry out degree of depth desalination, and reverse osmosis dense water gets into EDR system and carries out concentrated back again, produces water reflux and carries out the treatment to ozone catalytic oxidation section, and dense water is discharged, reaches the biggest water recovery effect that produces.

A device for desalination and recycling of fluoride washing wastewater is characterized in that a biochemical pretreatment section utilizes a high-density pool to remove large-particle-size suspended matters and inorganic fluoride ions, a biological aerated filter to remove small-particle-size suspended matters and easily degradable organic matters, a dissolved air floatation pool to remove small-particle-size suspended matters and surfactants, an ozone catalytic oxidation filter to degrade organic fluoride to break biological toxicity, an aerobic MBR pool to degrade organic matters to achieve better removal effect of suspended matters, biological toxic substances and surface active matters in fluoride washing wastewater, multistage filtration and ultrafiltration of a membrane pretreatment section are utilized to reduce SDI and turbidity, the purpose of slowing down membrane pollution is achieved, RO reverse osmosis-EDI is finally utilized to concentrate and desalt, and EDR is concentrated again to improve the water yield. The invention sequentially removes suspended matters with large particle size, soluble surface active substances, biological toxic substances, soluble organic substances and SDI by pretreatment, ensures the concentration efficiency of the subsequent desalting sections, improves the desalting rate by utilizing RO-EDI in the concentration sections, improves the water yield by utilizing EDR to treat concentrated water, and achieves better desalting recycling treatment effect of fluorine chemical washing wastewater.

Example 2: as shown in figures 1, 2, 3, 4, 5, 6 and 7, the fluoride washing wastewater desalination and resource utilization device mainly comprises a biochemical pretreatment section, namely a high-density tank 1.1, an aeration biological filter tank 1.2, a dissolved air flotation tank 1.3, an ozone catalytic oxidation filter tank 1.4 and an aerobic MBR tank 1.5, wherein the membrane pretreatment section comprises a multi-medium filter 2.1, an activated carbon filter 2.2, an ultrafiltration 2.3 and a reverse osmosis RO-EDI-EDR deep treatment section, namely a reverse osmosis RO3.1-EDR system 3.3-EDI system 3.4.

A desalination and recycling method for fluoride wash wastewater uses a high-density pool 1.1 to remove large-particle-size suspended matters in fluoride wash wastewater, and CaCO is added ₃ With Ca (OH) ₂ The precipitation of inorganic fluoride ions is enhanced by the double-alkali method, partial sludge is refluxed by a sludge reflux pump of a high-density tank 1.1, the sedimentation effect of suspended matters is enhanced, and the use amount of flocculant is reduced. The effluent from the high-density tank enters the aeration biological filter tank 1.2, the characteristics of developed micropores, strong interception capability, small resistance, high strength and good stability of the biochemical flocculation effect of microorganisms in the filter tank and the volcanic composite biological filter material are utilized to intercept small-particle-size suspended matters, and the easily degradable organic matters in the washing wastewater are treated, the preliminarily filtered effluent enters the dissolved air flotation tank 1.3, the dissolved organic matters such as the small-particle-size suspended matters in the sewage and the surfactant in the washing wastewater are removed by utilizing the high-efficiency dissolved air flotation device, the air flotation effluent enters the ozone catalytic oxidation filter tank 1.4, the organic fluoride is degraded by utilizing the proper OC proportion determined by small test and the carbon-based ozone catalytic oxidation process, the organic fluoride is degraded into easily degradable organic matters, the effluent enters the aerobic MBR tank 1.5, the fluorine ion content in the effluent is greatly reduced, the solid suspended matters and the content of the dissolved organic matters are greatly reduced by the degradation of aerobic bacteria in the aerobic tank, and the filtering effect of the MBR membrane is ensured, and the biochemical pretreatment effect is completed.

The pretreated effluent water quality is good, the secondary filtration is carried out through the multi-medium filter 2.1 and the activated carbon filter 2.2, the sewage before membrane feeding is ensured not to contain suspended matters with small particle size, the requirement that the effluent water meets the reverse osmosis turbidity of less than 1NTU and SDI of less than 5 is ensured to be lower after the ultrafiltration 2.3 treatment, and the scaling risk is not caused to the subsequent concentration.

The reverse osmosis RO3.1 is subjected to preliminary desalination treatment by using a two-stage desalination system, reverse osmosis produced water enters an EDI system 3.4 for deep desalination, reverse osmosis concentrated water enters an EDR system 3.3 for concentration again, produced water flows back to an ozone catalytic oxidation section for treatment, and concentrated water is discharged to achieve the maximum produced water recovery effect.

The biochemical pretreatment section utilizes a high-density tank 1.1 to remove large-particle-size suspended matters and inorganic fluoride ions, an aeration biological filter tank 1.2 to remove small-particle-size suspended matters and easily degradable organic matters, a dissolved air floatation tank 1.3 to remove small-particle-size suspended matters and surfactants, an ozone catalytic oxidation filter tank 1.4 to degrade organic fluoride to break biotoxicity, an aerobic MBR tank 1.5 to degrade organic matters to achieve better removal effect of suspended matters, biotoxic matters and surface active matters in fluorine chemical wastewater, and utilizes multistage filtration and ultrafiltration 2.3 of a membrane pretreatment section to reduce SDI and turbidity so as to achieve the aim of slowing down membrane pollution, and finally utilizes RO reverse osmosis-EDI concentration desalination and EDR reconcentration to improve the water production meeting rate.

The invention sequentially removes suspended matters with large particle size, soluble surface active substances, biological toxic substances, soluble organic substances and SDI by pretreatment, ensures the concentration efficiency of the subsequent desalting sections, improves the desalting rate by utilizing RO-EDI in the concentration sections, improves the water yield by utilizing EDR to treat concentrated water, and achieves better desalting recycling treatment effect of fluorine chemical washing wastewater.

The fluoride industry washing wastewater desalination resource utilization device mainly comprises a biochemical pretreatment section high-density tank, an aeration biological filter, a dissolved air floatation tank, an ozone catalytic oxidation filter, an aerobic MBR tank, a membrane pretreatment section multi-medium filter, an active carbon filter, ultrafiltration and reverse osmosis RO-EDI-EDR advanced treatment section. According to the invention, suspended matters, turbidity and COD are removed through the biochemical pretreatment section, the suspended matters, turbidity and SDI are removed through the membrane pretreatment section, the effect of achieving 95.92% of deep desalination water recovery rate in reverse osmosis RO concentration-EDI-EDR deep position is achieved, pure water is produced after the fluoride washing water is desalted, the recycling is achieved as production reuse water, and the recycling of the fluoride washing wastewater is achieved.

Example 3: as shown in fig. 1, fig. 2, fig. 3 and fig. 4, according to a system flow chart of desalination and recycling of fluoride wash wastewater in fig. 3, the device is divided into a biochemical pretreatment section high-density tank-aeration biological filter tank-dissolved air flotation tank-ozone catalytic oxidation filter tank-aerobic MBR tank, a membrane pretreatment section multi-media filter-activated carbon filter-ultrafiltration and reverse osmosis RO-EDI-EDR advanced treatment section, and in the practical implementation case, detailed process ratio selection is carried out according to specific water quality and operation conditions, and the specific contents are as follows:

1. Water quality and quantity of inlet and outlet water

1.1, quality of influent water

The wastewater of the invention is derived from washing wastewater in the production process of fluorine-containing resin, the water quality condition is shown in table 1-1,

TABLE 1-1 quality of incoming water

1.2, the water outlet index is shown in tables 1-2,

1 system wastewater discharge rate: less than or equal to 5 percent

2, water flow rate of produced water: more than or equal to 90t/h

TABLE 1-2 Water output index

According to the existing water quality and quantity requirements, the important points considered in the implementation process are as follows:

the design allowance is fully considered in the system design, and the whole system adopts 1.15 allowance coefficient. And a standby water pump and corresponding spare parts are additionally arranged according to the needs of each monomer, so that the continuous and stable operation of the system is ensured.

2, as land resources are precious, the adoption of the treatment technology should consider small occupied area and high operation efficiency. On the premise of meeting the requirements of construction, installation and maintenance, all the treatment structures are concentrated as much as possible, the occupied area is saved, and the greening area is enlarged.

And 3, the water inflow of the engineering is changed along with the time and season, the engineering considers the modular design concept, and the system operation combination can be performed according to the current water inflow and the future water inflow increasing condition so as to reduce the operation cost.

2. Process ratio selection

Biochemical pretreatment section step:

the biochemical pretreatment section comprises a high-density tank, a biological aerated filter, a dissolved air floatation tank, an ozone catalytic oxidation filter and an aerobic MBR tank, and is mainly characterized in that the technology before the aerobic MBR membrane tank in the technology is selected as follows:

The suspended matters and turbidity in the wastewater are higher, the sediment is a main unit for removing the suspended matters in the water, and the conventional sediment process for removing the suspended matters comprises the following steps: the inclined plate tube sedimentation tank, the horizontal flow sedimentation tank and the high-density sedimentation tank are shown in tables 1-3 and are compared with the common process.

Table 1-3 comparison of precipitation process

According to the comparison, the investment cost, the operation stability and the operation simplicity are comprehensively considered, the high-density sedimentation tank is selected to remove suspended matters and turbidity in water, and the high-density sedimentation tank and the air floatation tank are utilized to remove suspended matters and turbidity in wastewater, so that the method has the advantages of mature and stable process and high removal efficiency.

After the surface active substances and the suspended substances with large particle sizes are removed by the high-density sedimentation tank and the dissolved air flotation tank, the biological aerated filter is utilized to perform ozone catalytic oxidation and COD removal by the aerobic tank, so that the stable operation of a subsequent membrane system is ensured. The aeration biological filter has the functions of biodegradation and filtration, is a fully mature process, adopts volcanic composite biological filter materials, has developed micropores, strong pollution interception capability, small resistance, high strength and good stability, and can ensure the removal stability of COD.

The ozone catalytic oxidation process determines process parameters through experimental comparison, and the main flow is as follows:

a) According to an owner side experiment, determining that main COD and a blocking film pollutant source in the wastewater are dispersing agents, and ozone oxidation can effectively remove COD to relieve the blocking film condition;

b) Designing experiments, comparing treatment effects of the ozone catalytic oxidation and ozone contact oxidation processes, and determining that the process is ozone catalytic oxidation;

c) Determining process core parameters, ozone addition amount and contact time through experiments; the COD removing effect of the invention is ensured, and the phenomenon of blocking the membrane is avoided. The invention selects the carbon-based ozone catalytic oxidation process, does not produce secondary pollution, has strong oxidation capability, high reaction speed, high ozone utilization rate and low investment and operation cost. As shown in tables 1-4, the present invention is a well-recognized advanced technology for organic wastewater treatment.

Tables 1-4 comparison of ozone contact oxidation and catalytic ozone oxidation

The COD of raw water is less than or equal to 800mg/L, the COD entering the ozone catalytic oxidation system is calculated by the process design, the removal rate is 52.75%, the removal rate of 1350mg/L of the surfactant and 275mg/L of the surfactant according to the target pollutant is 52.75%, at the moment, the surfactant 1 with the corresponding concentration is 166mg/L, and the surfactant 2 is 36mg/L; the concentration of the surfactant 1 and the surfactant 2 at the moment is the concentration of the experimental small test, the previous experimental result is based on the concentration, the removal rate of the surfactant 1 reaches 91% and the film blockage prevention is the target value, and the COD removal amount is 195mg/L.

Comparing the oxidative degradation effect of the surfactant under 2 technological conditions of ozone contact oxidation and carbon-based catalyst catalytic ozone oxidation;

experimental conditions, according to empirical values, selecting O according to target removal rate ₃ The ozone adding amount is about 290-300mg/L, and the delta COD=1.5. From experimental data, the catalytic oxidation efficiency is obviously higher than that of contact oxidation, and the catalytic oxidation with the removal of COD amount can be improved by about 60mg/L with the same contact reaction time.

In summary, the carbon-based material catalytic ozonation process is significantly better than the conventional ozone contact oxidation, so the carbon-based material catalytic ozonation process is recommended to be used for advanced oxidative degradation of COD.

Membrane pretreatment stage: the membrane pretreatment section comprises a multi-medium filter, an activated carbon filter and an ultrafiltration, the multi-medium filter and the activated carbon filter ensure the water inflow stability of the ultrafiltration membrane and the reverse osmosis membrane, reduce the mechanical damage and pollution to the subsequent process, reduce the risk of blocking the membrane and ensure the recovery rate and the stability of the system. The process mainly performs comparison and selection on the ultrafiltration group device.

In order to meet the requirements of reverse osmosis turbidity less than 1NTU and SDI less than 5, suspended matters, organic matters and partial COD in water are further removed, and filtration with higher precision is required to be arranged, so that ultrafiltration is adopted as pretreatment before reverse osmosis at present.

As shown in tables 1-4, ultrafiltration is divided into tubular ultrafiltration and hollow fiber ultrafiltration, wherein hollow fiber ultrafiltration membrane products can be divided into pressure ultrafiltration and immersion ultrafiltration according to the form of a reactor, pressure ultrafiltration is divided into internal pressure ultrafiltration and external pressure ultrafiltration according to the form of a reactor, external pressure ultrafiltration is made of PVDF (polyvinylidene fluoride) materials in most cases, the ultrafiltration membrane is suitable for most sewage and wastewater treatment, the internal pressure membrane is made of PES (polyether sulfone) materials, the brittleness is high, the water inlet channel of the internal pressure membrane is small, and the sewage blockage is easy to occur. Tubular ultrafiltration is suitable for water with higher turbidity by its larger inner passage, but its higher flushing flow rate makes it have high running cost.

After metal salt is removed from the inlet water through multistage mixing reaction, precipitation and multi-medium filtration are carried out again, the turbidity in the water is low, and the operation energy consumption of the hollow fiber ultrafiltration membrane is lower, so that the use requirement can be completely met. However, the quality of the inflow water is high-salt wastewater, crystalline salt is easy to separate out in the operation process, the method is not suitable for aeration blowing to realize a membrane pollution cleaning mode, and the inner pressure membrane can be flushed at a large flow rate to ensure that the blocking problem of the crystalline salt is reduced.

Tables 1-5 Ultrafiltration Membrane comparison

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After COD of the inlet water is removed through multistage treatment reaction, the inlet water is filtered by multistage filter media again, the turbidity in the water is low, and the hollow fiber ultrafiltration membrane can completely meet the use requirement; the investment of the process is low, so that the external pressure type ultrafiltration membrane is adopted in the process.

Reverse osmosis RO-EDI-EDR advanced treatment stage: the reverse osmosis RO-EDI-EDR technology is adopted, and the technology mainly performs comparison selection on reverse osmosis and electrodialysis.

The reverse osmosis membrane element has the characteristics of wide flow passage, high water yield and high pollution resistance, and can bear ultrahigh water inlet pressure due to special element and membrane design, so that the recovery rate of salt in the process is improved; and in each concentration, the RO selection pressure container is a 6-core container, so that the water yield is more uniform, and the reverse osmosis system is ensured to be more stable and the final water yield is ensured. According to reverse osmosis simulation calculation software, the rationality of performance parameters such as flux, recovery rate, water supply flow, concentrate flow, water supply pressure, pressure drop between sections and the like of each reverse osmosis membrane element of each section is analyzed, and the optimal configuration of the reverse osmosis system is designed. The automatic valve quantity configuration of the invention realizes automatic start-up operation water production, automatic stop flushing, automatic cleaning, accident automatic stop alarming, automatic cleaning reminding and the like.

Different reverse osmosis membranes and technical couplings are selected according to different water quality of inflow water, so that the optimal operation cost performance is achieved.

As shown in fig. 5, 6 and 7, the roll-type reverse osmosis membrane RO has a spiral roll-type structure, which is simply called roll-type structure. Each leaf membrane bag consists of two membranes with opposite front sides, a product water channel between the two membranes and a turbulent flow grid-shaped water inlet channel arranged on the surface of the membrane, three sides of the membrane bag are sealed by an adhesive, and a fourth side is opened on a perforated produced water collecting pipe. Has the advantages of uniform water flow distribution, high pollution resistance, low replacement cost, simple external pipeline, easy cleaning and maintenance, and the like.

The invention discloses a coiled high-pressure reverse osmosis membrane STRO component, which is a novel structural membrane component specially developed for high-concentration wastewater treatment, wherein an industrial anti-pollution RO membrane is adopted as a membrane, a parallel grid structure different from a common coiled membrane is adopted as a grid channel, so that the coiled high-pressure reverse osmosis membrane can stably run for a long time in a place where the common coiled membrane cannot be applied, a trapezoid structure is adopted as a grid of the coiled high-pressure reverse osmosis membrane component, wastewater/feed liquid flows in a channel formed by the grid, the like flowing in a tubular membrane, the resistance diamond grid is much smaller, meanwhile, turbulence in the feed liquid flowing process can be increased by transverse reinforcing ribs in the interior, the concentration polarization effect of the membrane is reduced, and the pollution resistance of the ST membrane component is greatly improved.

Disc-tube reverse osmosis (DTRO), a form of reverse osmosis, is a membrane module specifically designed to treat high concentration organics and high salt wastewater, and its core technology is disc-tube membrane column. The reverse osmosis membrane and the hydraulic guide disc are stacked together, fixed by a central pull rod and an end plate, and then placed into a pressure-resistant sleeve, so that a membrane column is formed. DTRO overcomes the disadvantage of easy clogging of reverse osmosis systems in handling high organics and high salts.

Roll-type reverse osmosis membrane RO working principle: after entering from an inlet at one end of the membrane shell, the pressurized feed liquid passes through a feed liquid flow channel formed by a feed liquid separation net along the direction parallel to the central tube and flows through the surface of the membrane; in the process, part of liquid flows out from an outlet at the other end of the membrane shell to form concentrated liquid; and the other part of the liquid penetrating through the membrane passes through the penetrating liquid separation net flow passage in the membrane bag along the spiral direction, finally flows into the central tube and is led out. The flowing mode ensures the effective filtration of the feed liquid, leads the permeate liquid to be smoothly led out, and completes the whole filtration process.

Roll-type high-pressure reverse osmosis membrane STRO working principle: the material liquid flowing process of the STRO membrane element is the same as that of the roll RO; the structure is further optimized on the basis of the roll RO technology, the elements are combined with the design advantages of the open flow channel and the roll element, a unique 45-degree diamond double-layer open flow channel structure is innovatively adopted, the effective areas of the water inlet flow channel and the membrane are obviously optimized by the design structure, and meanwhile, the pressure is more stable; the design structure further improves the smoothness of the water inlet flow passage and the effective area of the membrane. In order to improve the efficiency of the fresh water channel and reduce the pressure loss, the STRO membrane element shortens the length of the blades and increases the number of the blades; the design shortens the length of the fresh water channel, thereby reducing the pressure loss of the fresh water channel, and simultaneously, the net pushing pressure of the membrane along the way tends to be the same, thereby maintaining the consistency of the water flux of different parts of the membrane surface. The design can reduce the degree of concentration polarization, so that the permeability of the membrane can be better exerted.

Disc Tube Reverse Osmosis (DTRO) principle of operation: the disc-tube type membrane component adopts an open flow channel, so that feed liquid can smoothly enter the pressure vessel and flow to the other end of the component through a channel between the flow guide disc and the shell. At the flange at the other end, the feed liquid enters the guide disc through 8 channels to form a short-distance path for fast flowing through the filtering membrane; after passing through the filtering membrane, the liquid reversely rotates to the other membrane surface at an angle of 180 degrees, and then flows into the next flow guide disc from the notch in the center of the flow guide disc. In this way, a double "S" shaped path is formed from the circumference of the diaphragm to the center of the circle, to the circumference, and to the center of the circle on the membrane surface. The concentrate finally flows out from the flange at the feeding end. The DT membrane component adopts a design with high strength and pressure resistance, and can bear higher osmotic pressure; the convex point flow guide disc forms a unique open flow channel, so that the anti-pollution capability of the membrane is improved, the pretreatment requirement is lower, the cleaning is more thorough, and the service life of the membrane is prolonged. This design makes the assembly more advantageous in dealing with various conditions.

Tables 1-6 roll reverse osmosis and roll high pressure reverse osmosis and DTRO techniques comparison

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As shown in tables 1-6 and described above, the roll reverse osmosis technology has the advantages of high effective salt recovery, low investment cost, low running cost, small occupied area and the like by integrating the conditions of technical maturity, occupied area, running cost, service life and concentrated water recovery, and has more obvious advantages by combining the condition of the water quality of the inlet water.

Therefore, the first-stage reverse osmosis and the second-stage reverse osmosis of the invention both adopt the roll reverse osmosis technology, and the effluent meets the reclaimed water recycling index required by the owners, thereby achieving the effect of the optimal overall process.

The pressure of the first concentration and the second concentration is 9.0bar and 8.9bar respectively, and the pressure of the second reverse osmosis is 8.6bar, so that the R-BW8040-FR4008 inch brackish water reverse osmosis membrane element sea water desalination membrane is selected during the first concentration and the second concentration, and the quality of the discharged water and lower operation cost are ensured to the maximum extent under the condition of meeting the pressure requirement.

For the EDR and EDI system after the reverse osmosis system, the process comparison is as follows:

EDR system: and the RO concentrated water is desalted again through EDR treatment, so that the water reuse amount is increased, and the discharge amount of the waste brine is reduced. According to the EDR system adopted by the invention, when the ionic concentration and conductivity of raw water fluctuate within a certain range, the operation parameters such as voltage, current, flow, pressure and the like can be regulated, the water yield and the water quality of the effluent can still be ensured, and the EDR system can realize different desalination rates of the wastewater by regulating the voltage and the current at will, so that the wastewater desalination is realized very conveniently. And EDR has the function of reversing the pole, reverses the pole through automatic control, effectively prevents scale deposit and deposits, possesses the automatically cleaning effect. In the invention, the first-stage RO concentrated water still contains partial COD in the produced water after entering the EDR system for treatment, so that the recycled produced water of the section is recycled to the ozone catalytic oxidation section for removing COD, the quality of the recycled water is ensured, and the risk of blocking the membrane is reduced.

EDI system: EDI is a revolutionary water treatment technology, which skillfully combines electrodialysis technology and ion exchange technology, and can continuously prepare high-quality pure water without acid and alkali. It has the advantages of advanced technology, simple and convenient operation and good environmental protection. The invention adopts the EDI system as the final step of the system, and stably ensures the quality of produced water.

The reverse osmosis technology and the electrodialysis have high-efficiency concentration function, and the comparison of various performances of the two technologies is shown in tables 1-7.

Tables 1-7 comparison of reverse osmosis and electrodialysis techniques

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As described above, the embodiments of the present invention have been described in detail, but it will be apparent to those skilled in the art that many modifications can be made without departing from the spirit and effect of the present invention. Accordingly, such modifications are also entirely within the scope of the present invention.

Claims

1. The desalination and recycling method for the fluoride wash wastewater is characterized by comprising the following steps of: a pretreatment section step, a biochemical pretreatment section step, a membrane pretreatment section step, a reverse osmosis RO-EDI-EDR deep treatment section step and a pretreatment section step: precipitating inorganic fluoride ions and suspended matters by using a high-density sedimentation tank, performing preliminary filtration and preliminary biochemical degradation by using a biological aerated filter, further removing soluble matters and surface active matters by using an air floatation tank, degrading organic fluorine by using ozone catalytic oxidation of effluent, reducing biological toxic matters, removing organic matters and suspended matters by using the effluent after entering an aerobic MBR, and performing final trace removal of suspended matters and organic matters by using multi-medium filtration and active carbon filtration before entering a membrane system, thereby ensuring the water quality of membrane-entering sewage; concentrating by UF+RO double membrane method, desalting by EDR, and increasing water yield.

2. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the step of biochemical pretreatment is as follows: fluoride removal using dense pondsLarge particle size suspended matters in the washing wastewater are added by adding CaCO ₃ With Ca (OH) ₂ The precipitation of inorganic fluoride ions is enhanced by a double-alkali method, partial sludge is refluxed by a sludge reflux pump of a high-density tank, the sedimentation effect of suspended matters is enhanced, the consumption of flocculant is reduced, effluent from the high-density tank enters an aeration biological filter tank, the small-particle-size suspended matters are intercepted by the biochemical flocculation effect of microorganisms in the filter tank, and organic matters which are easy to degrade in washing wastewater are treated, primary filtered effluent enters an air-dissolving floatation tank to remove the small-particle-size suspended matters in the sewage and the soluble organic matters such as surfactants in the washing wastewater by a high-efficiency air-dissolving floatation device, the air-floating effluent enters an ozone catalytic oxidation filter tank to degrade the organic fluoride by using a proper OC proportion, the organic fluoride is degraded into organic matters which are easy to degrade, effluent enters an aerobic MBR tank to degrade by aerobic bacteria in the aerobic tank, the filtration effect of an MBR membrane is ensured, the fluorine ion content in the effluent is greatly reduced, the solid suspended matters and the soluble organic matter content is greatly reduced, and the biochemical pretreatment effect is completed.

3. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the step of the membrane pretreatment section is as follows: the pretreated sewage is subjected to secondary filtration through a multi-medium filter and an activated carbon filter, so that the sewage before membrane feeding does not contain suspended matters with small particle size, and the ultrafiltration treatment ensures that the effluent meets lower requirements of reverse osmosis turbidity less than 1NTU and SDI less than 5 and does not cause scaling risk to subsequent concentration.

4. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the reverse osmosis RO-EDI-EDR advanced treatment stage comprises the steps of: the reverse osmosis RO uses a two-stage desalting system to carry out preliminary desalting treatment, reverse osmosis produced water enters an EDI system to carry out deep desalting, reverse osmosis concentrated water enters the EDR system to carry out concentration again, produced water flows back to an ozone catalytic oxidation section to carry out treatment, and the concentrated water is discharged to achieve the maximum produced water recovery effect.

5. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the step of biochemical pretreatment is as follows: the high-density pool is utilized to remove large-particle-size suspended matters and inorganic fluorine ions, the aeration biological filter pool is utilized to remove small-particle-size suspended matters and easily degradable organic matters, the dissolved air flotation pool is utilized to remove small-particle-size suspended matters and surface active agents, the ozone catalytic oxidation filter pool is utilized to degrade organic fluoride to break biological toxicity, and the aerobic MBR pool is utilized to degrade organic matters to achieve better removal effect of suspended matters, biological toxic matters and surface active matters in fluorine chemical wastewater.

6. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the step of the membrane pretreatment section is as follows: the SDI and turbidity are reduced through multistage filtration and ultrafiltration, the purpose of slowing down membrane pollution is achieved, RO reverse osmosis-EDI is finally utilized for concentration and desalination, EDR is used for concentration again, and the water yield is improved.

7. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the pretreatment step comprises: the concentration efficiency of the subsequent desalination section is ensured by sequentially removing large-particle-size suspended matters, soluble surface active substances, biological toxic substances, soluble organic substances and SDI, the desalination rate is improved by utilizing RO-EDI in the concentration section, the water yield is improved by utilizing EDR to treat concentrated water, and the desalination recycling treatment effect of the fluoride washing wastewater is achieved.

8. The method for desalination and recycling of fluoride wash wastewater according to claim 1, wherein the reverse osmosis RO-EDI-EDR advanced treatment stage comprises the steps of: the reverse osmosis RO uses a two-stage desalting system to carry out preliminary desalting treatment, reverse osmosis produced water enters an EDI system to carry out deep desalting, reverse osmosis concentrated water enters the EDR system to carry out concentration again, produced water flows back to an ozone catalytic oxidation section to carry out treatment, and the concentrated water is discharged to achieve the maximum produced water recovery effect.

9. A device for desalination and recycling of fluoride wash wastewater is characterized in that fluoride wash wastewater is connected to an adjusting tank, the water outlet of the adjusting tank is connected to the water inlet of a high-density sedimentation tank, the water outlet of the high-density sedimentation tank is connected to a biological aerated filter, the mud outlet of the high-density sedimentation tank is discharged to a mud storage tank, the water outlet of the biological aerated filter is connected to an air floatation tank, the backwash water outlet of the biological aerated filter is discharged to the adjusting tank, the water outlet of the air floatation tank is connected to an ozone catalytic oxidation unit, the scum outlet of the air floatation tank is discharged to the mud storage tank, the water outlet of the ozone catalytic oxidation unit is connected to an aerobic MBR membrane tank, the backwash water outlet of the ozone catalytic oxidation unit is discharged to the adjusting tank, the water outlet of the aerobic MBR membrane tank is connected to an intermediate water tank, the mud outlet of the aerobic MBR membrane tank is discharged to the mud storage tank, the mud storage tank is connected to a plate frame dehydrator, the mud of the plate frame dehydrator is transported outside, the filtrate outlet of the plate frame dehydrator is discharged to the adjusting tank, the water outlet of the middle water tank is connected with a multi-medium filter, the water outlet of the multi-medium filter is connected with an activated carbon filter, the backwash water outlet of the multi-medium filter is discharged to a regulating tank, the water outlet of the activated carbon filter is connected with ultrafiltration, the backwash water outlet of the activated carbon filter is discharged to the regulating tank, the ultrafiltration water outlet is connected with an ultrafiltration water producing tank, the ultrafiltration water producing tank water outlet is connected with a first-stage RO-1 water producing tank, the first-stage RO-1 water concentrating port is connected with a concentrated water tank, the water outlet of the concentrated water tank is connected with a first-stage RO-2, the water producing port of the first-stage RO-2 is connected with a first-stage water producing tank, the concentrated water port of the first-stage RO-2 is connected with a concentrated water tank 2, the water outlet of the concentrated water tank 2 is connected with an EDR system, the water producing port of the EDR system is connected with an ozone catalytic oxidation unit, the EDR system is discharged with concentrated water, the water outlet of the first-stage water producing tank is connected with a second-stage RO, the second-stage RO water outlet is connected to the second-stage water producing tank, the second-stage RO water concentrating port is connected to the concentrated water tank, the second-stage water producing tank water outlet is connected to the EDI system, the EDI system water outlet is connected to the nitrogen seal water tank, the EDI system water concentrating port is connected to the first-stage water producing tank, and the nitrogen seal water tank water outlet is connected to the recycling pipeline.