CN114149103A - Membrane treatment recycling concentration method - Google Patents

Membrane treatment recycling concentration method Download PDF

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Publication number
CN114149103A
CN114149103A CN202111451129.0A CN202111451129A CN114149103A CN 114149103 A CN114149103 A CN 114149103A CN 202111451129 A CN202111451129 A CN 202111451129A CN 114149103 A CN114149103 A CN 114149103A
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water
nanofiltration
wastewater
membrane
reverse osmosis
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王宗葳
马文明
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China Construction Eco Environmental Group Co Ltd
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China Construction Eco Environmental Group Co Ltd
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Priority to CN202111451129.0A priority Critical patent/CN114149103A/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
    • C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
    • C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
    • C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
    • C02F5/14—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances containing phosphorus

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention relates to the technical field of sewage treatment, in particular to a membrane treatment resource concentration method, which comprises the following steps: pretreating the wastewater to be treated; primarily filtering the pretreated wastewater; separating the wastewater after the primary filtration treatment by using a nanofiltration membrane component to respectively obtain nanofiltration product water and nanofiltration concentrated water; separating the nanofiltration concentrated water by using a first seawater reverse osmosis membrane component to obtain fresh water and a sodium sulfate solution; separating nanofiltration produced water by using a brackish water membrane component and a second seawater reverse osmosis membrane component in sequence to obtain fresh water and a sodium chloride solution; wherein, the step S4 and the step S5 have no sequential limitation. Compared with other conventional treatment methods, the membrane treatment resource concentration method has the advantages of low equipment investment cost, capability of greatly reducing the operation cost, wide application range and suitability for municipal sewage, coal chemical wastewater, power plant wastewater and the like.

Description

Membrane treatment recycling concentration method
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a membrane treatment resource concentration method.
Background
The thermal power plant has low requirement on the quality of circulating cooling water make-up water, so that the secondary treated water of the sewage treatment plant is recycled as the circulating cooling water make-up water after being deeply treated, the discharge amount of urban sewage can be reduced, and the water production cost of the sewage treatment plant is far lower than that of a seawater desalination system and is considered preferentially.
However, in coastal areas where water resources are scarce, the salt content in available fresh water resources is high due to factors such as over-exploitation of water resources and reverse flow of seawater. The effluent of the sewage treatment plant is simply treated and then used as the recirculated cooling water make-up water of the power plant, the high salt content of the effluent cannot meet the water quality requirement of the recirculated cooling water make-up water of the power plant, and a reverse osmosis desalination system is required to be additionally arranged.
Salt substances in the coal chemical industry salt-containing wastewater mainly come from raw water, raw material coal, water generated in the production process and medicaments (such as acid-base neutralization, flocculation, scale inhibition, bactericide and the like) added in the water treatment process. In the production link, salt substances mainly come from coal gas washing wastewater, circulating water system drainage, desalted water system drainage, recycling system concentrated water and the like in the production process, and sometimes also include effluent after biochemical treatment, and the wastewater and the effluent generally have the problem of high salt content. Therefore, the saline coal chemical wastewater as the process circulating water must be subjected to advanced treatment.
The advanced treatment is a new requirement in the field of water treatment in China in recent years, and mainly aims to cooperate with reclaimed water reuse, further improve the utilization rate of water resources and reduce the waste amount of the water resources.
The evaporative crystallization technology is a mature sewage advanced treatment technology at present, but the technology has the problems of high investment cost, difficult operation and maintenance and high operation cost.
Therefore, in order to solve the above problems, it is an urgent technical problem for those skilled in the art to develop a membrane treatment resource concentration method.
Disclosure of Invention
The invention aims to provide a membrane treatment resource concentration method, which effectively realizes resource utilization of salt-containing wastewater.
The invention provides a membrane treatment resource concentration method, which comprises the following steps:
s1, pretreating the wastewater to be treated;
s2, primarily filtering the pretreated wastewater;
s3, separating the wastewater after the primary filtration treatment by using a nanofiltration membrane component to respectively obtain nanofiltration product water and nanofiltration concentrated water;
s4, separating the nanofiltration concentrated water by using a first seawater reverse osmosis membrane component to obtain fresh water and a sodium sulfate solution;
s5, separating the nanofiltration produced water by using a brackish water membrane component and a second seawater reverse osmosis membrane component in sequence to obtain fresh water and a sodium chloride solution;
wherein, the step S4 and the step S5 have no sequential limitation.
The method aims to solve the problems that the salt-containing wastewater treatment technology in the prior art has high investment and operation cost, low resource utilization rate and can not realize zero discharge of salt-containing wastewater. In the membrane treatment resource concentration method, firstly, wastewater to be treated is pretreated, so that the stability of the quality of the wastewater to be treated is ensured; then, the pretreated wastewater is preliminarily filtered to intercept substances such as colloid and organic matters which are harmful to the membrane and play a role in protecting the membrane of the subsequent process; the raw water is treated by a nanofiltration membrane component, and the nanofiltration membrane component can intercept divalent ions and recover monovalent ions, so that the primary separation of the raw water is realized; clean water containing monovalent ions and obtained by recycling the nanofiltration membrane component sequentially enters the brackish water membrane component and the second seawater reverse osmosis membrane component to further treat the clean water containing monovalent ions so as to obtain fresh water and a sodium chloride solution; and the concentrated water containing divalent ions intercepted by the nanofiltration membrane component enters the first seawater reverse osmosis membrane component to further treat the concentrated water containing divalent ions, so that fresh water and concentrated water containing sodium sulfate are obtained, and finally the resource utilization of salt-containing wastewater is realized.
Preferably, in the present technical solution, step S1 specifically includes: adjusting the pH value of the wastewater to be treated to 6-8, and adding a reducing agent and a scale inhibitor.
In order to control the membrane pollution, a reducing agent and a scale inhibitor are added before the wastewater enters a membrane device so as to remove scale and other pollutants in the wastewater.
Preferably, in the present technical solution, step S2 specifically includes: inputting the pretreated wastewater into a cartridge filter for primary filtration, wherein the pressure difference between the outlet and the inlet of the cartridge filter is not more than 10%.
The cartridge filter is internally provided with hollow fiber membranes which are uniformly distributed, wastewater enters from the bottom and flows out from the upper part through the hollow fiber membranes, and the cartridge filter is mainly used for intercepting substances harmful to the membranes, such as colloids and organic matters, so as to protect the subsequent process membranes. When the outlet and inlet pressures of the cartridge filter exceed 10%, the cartridge filter needs to be physically cleaned or chemically cleaned.
Preferably, in step S3, when the nanofiltration membrane module is used for separation, the water inlet pressure is controlled to be 2-6atm, the temperature is controlled to be 25-40 ℃, and the pH is controlled to be 2-11.
Under the conditions, the nanofiltration membrane component can intercept divalent ions, the recovery rate of the monovalent ions is 97%, and the recovery rate of produced water can reach 90%.
Preferably, in step S4, when the first seawater reverse osmosis membrane module is used for separation, the water inlet pressure is controlled to be 50-70atm, the pH value is controlled to be 7-10, and the yield of produced water is within 75%.
Preferably, in step S5, when the brackish water membrane module is used for separation, the water inlet pressure is controlled to be 2-6atm, the temperature is 15-45 ℃, the pH value is 2-11, and the SDI is less than or equal to 4.
When the brackish water membrane module is used for separation, in order to ensure the optimal separation efficiency, the water inlet pressure is controlled to be 2-6atm, the temperature is 15-45 ℃, the pH value is 2-11, and the SDI is less than or equal to 4, wherein the SDI is the content of reaction colloid, turbidity and suspended matters.
Preferably, in step S5, when the second seawater reverse osmosis membrane module is used for separation, the water inlet pressure is controlled to be 45-50atm, the pH value is controlled to be 7-10, and the yield of the produced water is within 80%.
Preferably, the reducing agent and the scale inhibitor are added into the wastewater before the nanofiltration membrane component, the brackish water membrane component, the first seawater reverse osmosis membrane component and the second seawater reverse osmosis membrane component are used for separation.
Preferably, in the technical scheme, the addition amount of the reducing agent is 1-5mg/L, the addition amount of the scale inhibitor is 1-5mg/L, wherein the reducing agent is NaHSO4The scale inhibitor is an organic phosphoric acid scale and corrosion inhibitor.
As is preferred in the present solution, the present invention,before a nanofiltration membrane component, a brackish water membrane component, a first seawater reverse osmosis membrane component and a second seawater reverse osmosis membrane component are used for separation, chlorination and dechlorination treatment are sequentially carried out on the wastewater, and residual chlorine is controlled to be 1mg/L, wherein a reagent used for dechlorination is Na2SO3。
Excessive temperature tends to promote the growth of bacteria, and chlorination is a method for sterilization by adding Na2SO3The reducing agent can remove residual chlorine, and the residual chlorine is preferably controlled within 1 mg/L.
Compared with the prior art, the membrane treatment resource concentration method has the following advantages:
1. in the membrane treatment resource concentration method, firstly, wastewater to be treated is pretreated, so that the stability of the quality of the wastewater to be treated is ensured; then, the pretreated wastewater is preliminarily filtered to intercept substances such as colloid and organic matters which are harmful to the membrane and play a role in protecting the membrane of the subsequent process; the raw water is treated by a nanofiltration membrane component, and the nanofiltration membrane component can intercept divalent ions and recover monovalent ions, so that the primary separation of the raw water is realized; clean water containing monovalent ions and obtained by recycling the nanofiltration membrane component sequentially enters the brackish water membrane component and the second seawater reverse osmosis membrane component to further treat the clean water containing monovalent ions so as to obtain fresh water and a sodium chloride solution; the concentrated water containing divalent ions intercepted by the nanofiltration membrane component enters a first seawater reverse osmosis membrane component to further treat the concentrated water containing divalent ions so as to obtain fresh water and concentrated water containing sodium sulfate, and finally realize the resource utilization of the salt-containing wastewater;
2. compared with other conventional treatment methods, the membrane treatment resource concentration method has low equipment investment cost and can greatly reduce the operation cost;
3. the membrane treatment resource concentration method disclosed by the invention is wide in application, and can be suitable for municipal sewage, coal chemical wastewater, power plant wastewater and the like;
4. the membrane treatment resource concentration method has the advantages of extremely convenient operation, operation and maintenance, strong practicability and strong automation, and can realize unattended operation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic view of a membrane treatment resource concentration system according to the present invention.
Description of reference numerals:
1: a liquid storage tank; 2: a cartridge filter; 3: a concentrated water tank; 4: a first seawater reverse osmosis membrane module; 5: a water production tank; 6: a brackish water membrane module; 7: a second seawater reverse osmosis membrane module; 8: a sodium chloride water tank; 9: a fresh water tank; 10: a sodium sulfate water tank; 11: a water inlet pump; 12: a first flow meter; 13: a first high pressure pump; 14: a centrifugal pump; 15: a pressure gauge; 16: a first service line; 17: a second service line; 18: a third service line; 19: a nanofiltration membrane module; 20: a medicament adding component.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. Furthermore, the terms "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The invention also discloses a treatment system optimized by the resource concentration method, which comprises a liquid storage tank 1, a security filter 2, a nanofiltration mechanism, a concentrated water treatment mechanism and a produced water treatment mechanism; the liquid storage tank 1, the security filter 2 and the nanofiltration mechanism are communicated in sequence; and a clear liquid outlet of the nanofiltration mechanism is communicated with the produced water treatment mechanism, and a concentrated liquid outlet of the nanofiltration mechanism is communicated with the concentrated water treatment mechanism.
Wherein, the liquid storage tank 1 is used for homogenizing, and the stability of the quality of the sewage to be treated is ensured; hollow fiber membranes are uniformly distributed in the cartridge filter 2, and are mainly used for intercepting substances harmful to the membranes, such as colloids and organic matters, and protecting the membranes in the subsequent process; the nanofiltration mechanism can intercept divalent ions and recover monovalent ions, so that the primary separation of raw water is realized; clear water containing monovalent ions and recovered by the nanofiltration mechanism enters the water production treatment mechanism to further treat the clear water containing monovalent ions so as to obtain fresh water and concentrated water containing sodium chloride; and the nanofiltration mechanism intercepts the obtained concentrated water containing the divalent ions and enters the concentrated water treatment mechanism to further treat the concentrated water containing the divalent ions, so that fresh water and concentrated water containing sodium sulfate are obtained, and finally the resource utilization of salt-containing wastewater is realized. Compared with other conventional treatment systems, the membrane treatment resource concentration system has low overall operation and maintenance cost, and each unit plays a role and serves mutually, so that zero emission and resource utilization of the salt-burning wastewater are realized.
On the basis of the technical scheme, further, the concentrated water treatment mechanism comprises a concentrated water tank 3 and a first seawater reverse osmosis membrane component 4, and a concentrated liquid outlet of the nanofiltration mechanism, the concentrated water tank 3 and the first seawater reverse osmosis membrane component 4 are communicated in sequence. The water production treatment mechanism comprises a water production tank 5, a brackish water membrane assembly 6 and a second seawater reverse osmosis membrane assembly 7, and a clear liquid outlet of the nanofiltration mechanism, the water production tank 5, the brackish water membrane assembly 6 and the second seawater reverse osmosis membrane assembly 7 are communicated in sequence.
Specifically, the concentrated water treatment mechanism comprises a concentrated water tank 3 and a first seawater reverse osmosis membrane module 4, and the produced water treatment mechanism comprises a produced water tank 5, a brackish water membrane module 6 and a second seawater reverse osmosis membrane module 7. Wherein, the water production tank 5 and the concentrated water tank 3 are arranged on the same principle as the liquid storage tank 1, and are used as the transition of the subsequent treatment process while playing a protective role, so as to ensure that the subsequent membrane treatment device has stable water inlet. The first seawater reverse osmosis membrane component 4 can treat the concentrated water containing divalent ions so as to obtain fresh water and concentrated water containing sodium sulfate; the brackish water membrane module 6 can treat monovalent ions to obtain fresh water and a sodium chloride solution containing the monovalent ions; the sodium chloride solution containing monovalent ions further enters a second seawater reverse osmosis membrane component 7 for further concentration, and then fresh water and sodium chloride are obtained.
On the basis of the above preferred technical solution, more preferably, the system further comprises a sodium chloride water tank 8, a fresh water tank 9 and a sodium sulfate water tank 10, wherein a clear liquid outlet of the brackish water membrane module 6 is communicated with the fresh water tank 9, a clear liquid outlet of the second seawater reverse osmosis membrane module 7 is communicated with the fresh water tank 9, and a concentrated liquid outlet of the second seawater reverse osmosis membrane module 7 is communicated with the sodium chloride water tank 8; and a clear liquid outlet of the first seawater reverse osmosis membrane component 4 is communicated with the fresh water tank 9, and a concentrated liquid outlet of the first seawater reverse osmosis membrane component 4 is communicated with the sodium sulfate water tank 10.
In a specific embodiment of the invention, the device further comprises a sodium chloride water tank 8, a fresh water tank 9 and a sodium sulfate water tank 10, the nanofiltration mechanism performs primary separation on raw water to respectively obtain concentrated water containing divalent ions and clear water containing monovalent ions, wherein the clear water containing monovalent ions enters the brackish water membrane module 6 from the water production tank 5, the brackish water membrane module 6 is similar to a reverse osmosis membrane module to respectively obtain fresh water and a sodium chloride solution containing monovalent ions, the fresh water enters the fresh water tank 9, the sodium chloride solution containing monovalent ions further enters the second seawater reverse osmosis membrane module 7 for further concentration to further obtain fresh water and sodium chloride, the fresh water enters the fresh water tank 9, and the sodium chloride enters the sodium chloride water tank 8; and the concentrated water containing divalent ions enters the first seawater reverse osmosis membrane module 4 from the concentrated water tank 3 to further treat the concentrated water containing divalent ions so as to obtain fresh water and concentrated water containing sodium sulfate, wherein the fresh water enters the fresh water tank 9, and the sodium sulfate solution enters the sodium sulfate water tank 10. Finally, the concentration of chloride ions in the sodium chloride water tank 8 can reach 2453 mg/L, and the concentration of sulfate ions is 988 mg/L: the concentration of chloride ions in the sodium sulfate water tank 10 is 8312mg/L, and the concentration of sulfate ions in the sodium sulfate water tank 10 is 52678 mg/L. Therefore, the separation of different salts is realized, and the resource treatment and utilization of the sewage are further realized.
On the basis of the technical scheme, a water inlet pump 11 and a first flowmeter 12 are sequentially arranged on a pipeline for communicating the liquid storage tank 1 with the security filter 2, and a water outlet of the first flowmeter 12 is reversely communicated with the liquid storage tank 1; a first high-pressure pump 13 is arranged on a pipeline for communicating the water production tank 5 with the brackish water membrane module 6, and a water outlet of the first high-pressure pump 13 is reversely communicated with the water production tank 5; a centrifugal pump 14 is arranged on a pipeline for communicating the concentrated water tank 3 with the first seawater reverse osmosis membrane assembly 4, and a water outlet of the centrifugal pump 14 is reversely communicated with the concentrated water tank 3.
Specifically, a floating ball interlocking switch is arranged in the liquid storage tank 1 and is interlocked with the water inlet pump 11 and the valve, and when the water level in the liquid storage tank 1 is low, the water inlet pump 11 stops to prevent the water inlet pump 11 from idling and burning the water inlet pump 11. In addition, in order to ensure a certain water inlet flow of the nanofiltration mechanism, a first flowmeter 12 is arranged on a pipeline which is communicated with the liquid storage tank 1 and the security filter 2 so as to ensure that the water inlet flow of the nanofiltration mechanism is in a reasonable range, because the nanofiltration mechanism has certain requirements on the water inlet flow, the water inlet flow is lower, the concentrated water is not uniformly disturbed, the pollutants are easy to pollute the membrane, the water inlet flow is high, and the pollution of the membrane is accelerated. The water outlet of the first flowmeter 12 is reversely communicated with the liquid storage tank 1, the water outlet of the first high-pressure pump 13 is reversely communicated with the water production tank 5, and the water outlet of the centrifugal pump 14 is reversely communicated with the concentrated water tank 3, so that the stability of water quality can be further improved, and water to be treated can be directly conveyed to original storage equipment when subsequent membrane process equipment needs to be overhauled.
On the basis of the technical scheme, the nanofiltration mechanism further comprises a plurality of nanofiltration membrane components 19 which are arranged in parallel. And, specifically, the nanofiltration membrane component 19 is made of polyacrylonitrile material with excellent corrosion resistance.
On the basis of the technical scheme, pressure gauges 15 are arranged on a water inlet pipeline and a water outlet pipeline of the security filter 2, and a first maintenance pipeline 16 is arranged between the liquid storage tank 1 and the security filter 2; a pressure gauge 15 is arranged on a water inlet pipeline and a water outlet pipeline of each nanofiltration membrane component 19, and a second overhaul pipeline 17 is arranged between the cartridge filter 2 and the concentrated water tank 3; a pressure gauge 15 is arranged on a water inlet pipeline of the second seawater reverse osmosis membrane module 7, and a third overhaul pipeline 18 is arranged between the brackish water membrane module 6 and the sodium chloride water tank 8.
A pressure gauge 15 and a flowmeter are arranged between the protector and the water inlet pump 11, the flow and the pressure can be judged, and whether the water inlet flow is an appropriate value can be further calculated; pressure gauges 15 are arranged on the water inlet pipeline and the water outlet pipeline of the cartridge filter 2, whether the cartridge filter 2 needs to be cleaned or not can be judged through the pressure values of the inlet and the outlet of the cartridge filter 2, and when the pressure of the inlet and the outlet exceeds 10%, the cartridge filter 2 needs to be cleaned physically or chemically. In addition, a first maintenance pipeline 16 is arranged between the liquid storage tank 1 and the security filter 2, and when the security filter 2 needs to be cleaned, sewage in the liquid storage tank 1 can directly enter a subsequent nanofiltration mechanism.
Specifically, the hollow fiber membrane material in the cartridge filter 2 is polyvinylidene fluoride with good chemical stability.
In a similar way, a pressure gauge 15 is arranged on a water inlet pipeline and a water outlet pipeline of the nanofiltration membrane component 19, a second overhaul pipeline 17 is arranged between the security filter 2 and the concentrated water tank 3, when the pressure value is higher than the maximum, sewage directly enters the concentrated water tank 3 through the security filter 2, and the backwashing device is started to clean the nanofiltration mechanism. A pressure gauge 15 is arranged on a water inlet pipeline of the second seawater reverse osmosis membrane assembly 7, a third maintenance pipeline 18 is arranged between the brackish water membrane assembly 6 and the sodium chloride water tank 8, when the pressure value is higher than a preset value, sewage directly enters the concentrated water tank 3 from the brackish water membrane assembly 6, and meanwhile, a reverse washing device is started to clean the second seawater reverse osmosis membrane assembly 7.
On the basis of the technical scheme, further, a medicament adding part 20 is arranged on the water inlet pipeline of the nanofiltration membrane component 19, the brackish water membrane component 6, the first seawater reverse osmosis membrane component 4 and the second seawater reverse osmosis membrane component 7.
Specifically, in order to prevent the pollution of the control membrane, a medicament adding part 20 is arranged at the water inlet of all the membrane components and is used for adding a reducing agent and a scale inhibitor. Wherein the reducing agent is mainly NaHSO4The substances can form stable complexes with ions such as iron, copper, zinc and the like, and can dissolve oxides on the surface of metal; the scale inhibitor adopts an organic phosphoric acid scale and corrosion inhibitor, has good scale inhibition effect and wide application range, can play a good role in inhibiting scale and dispersing normal water quality, is particularly suitable for scale caused by precipitation of carbonate, sulfate, calcium oxide, magnesium oxide and ferric oxide, has high scale inhibition efficiency, and cannot be coagulated with residual coagulant or aluminum-rich and iron-rich compounds to generate condensate.
In addition, the water outlet pipelines of the liquid storage tank 1, the concentrated water tank 3 and the water production tank 5 are provided with chlorine adding pipelines and are positioned at the outlets of the corresponding water inlet pump 11, the centrifugal pump 14 and the first high-pressure pump 13, and meanwhile, a mixer is arranged, so that chlorine and inlet water can be uniformly mixed. The reason is that bacteria are easy to grow due to overhigh temperature, chlorine is a sterilization method, residual chlorine can be removed by adding a sodium sulfite reducing agent, and the residual chlorine is preferably controlled to be 1 mg/L.
It should be noted here that the brackish water membrane modules 6 are provided in multiple stages in parallel, so as to prevent scaling due to over-solubility deposition of the insoluble salt components when the recovery rate of the single-stage brackish water membrane modules 6 is too high, and to prevent scaling due to concentration polarization due to too low flow velocity of the concentrated water in the brackish water membrane modules 6, and to prevent colloids, suspended solids and the like in water from being discharged.
On the basis of the technical scheme, further, receive filter membrane subassembly 19 bitter salt water membrane subassembly 6 first sea water reverse osmosis membrane subassembly 4 with all be provided with online residual chlorine monitor and SDI monitor on the inlet channel of second sea water reverse osmosis membrane subassembly 7.
Particularly, all be provided with on-line chlorine residue monitor and SDI monitor on the inlet channel of all membrane modules to master into water at any time and pollute the condition to the membrane.
On the basis of the technical scheme, a medicament adding component 20 is further arranged on a pipeline for communicating the liquid storage tank 1 and the security filter 2.
By the medicament adding component 20, acid-base reagents can be added into the water outlet of the liquid storage tank 1 so as to ensure that the pH value of the inlet water of the cartridge filter 2 meets the design requirement.
When the method of the invention is used for treating the coal chemical wastewater, the water quality condition to be treated is as follows:
inflow rate of 10m3The pH value is about 4, the COD is 75mg/L, the nitrate ion concentration is 222mg/L, the chloride ion concentration is 1126mg/L, the sulfate ion concentration is 1383mg/L, the calcium ion content is 0.1mg/L, and the magnesium ion content is 0.1 mg/L.
Step S1: pretreating coal chemical wastewater to be treated in a liquid storage tank, adjusting the pH value to 6-8 by using a sodium hydroxide solution,
step S2: the liquid in the liquid storage tank is input into the security filter through the water inlet pump and enters the security filterAdding a reducing agent and a scale inhibitor, wherein the addition amount of the scale inhibitor, namely the organic phosphoric acid scale and corrosion inhibitor is 3mg/L, and the reducing agent NaHSO4The addition amount is 3mg/L, the mixture is uniformly input into a cartridge filter through a mixer, the water inlet pressure is 2atm, and the water outlet pressure is 1.8atm after the mixture passes through the cartridge filter.
Step S3: the wastewater after primary filtration by the cartridge filter enters a nanofiltration membrane component, the pressure of inlet water is raised to 4atm by a high-pressure pump, the inlet water temperature is about 25-30 ℃, the pH is about 8.5, the outlet water pressure is 3.8atm when the system is just started to operate, the system stably operates, the water yield is 90 percent, namely the ratio of the water yield after nanofiltration passes through the membrane to the inlet water, and the inlet water is 10m3H, 9m of produced water31m of concentrated water3(ii) a In addition, the salt separation rate takes chloride ions and sulfate ions as an example, the recovery rate of the chloride ions is 90 percent, the retention rate of the sulfate radicals is 97 percent, namely, the concentration of the produced water chloride ions accounts for 90 percent of the concentration of the inlet water chloride ions, the concentration of the produced water sulfate ions accounts for 1031mg/L, the concentration of the produced water sulfate ions accounts for 3 percent of the concentration of the inlet water sulfate ions, the concentration of the produced water sulfate ions is 41.49mg/L, the nanofiltration produced water enters a water production tank, and the nanofiltration concentrated water enters a concentrated water tank;
step S4: the water in the water production tank is delivered into the bitter salt water membrane component through a first high-pressure pump, the delivery pressure of the high-pressure pump is 15atm, the water production rate is 80 percent, namely the water produced by the bitter salt water membrane component accounts for 80 percent of the water inlet proportion, and the water produced by the bitter salt water membrane component is 7.2m3The concentrated water is 1.8m3/h, and Na is added into the feed water2SO3Removing residual chlorine by using a reducing agent to control the residual chlorine within 1mg/L and controlling the SDI of inlet water to be 2; the concentrated water passing through the brackish water membrane component enters a second seawater reverse osmosis membrane component through a high-pressure pump for further concentration, the pressure increase pressure of the concentrated water passing through the high-pressure pump is 47atm, the pH value of inlet water is about 8.2, the yield of the produced water is 80 percent, namely the inlet water is 1.8m3The water yield is 1.44m3And the system runs stably. After the step, the concentration of chloride ions in the concentrated water generated by the second seawater reverse osmosis membrane component can reach 2453 mg/L, and the concentration of sulfate ions is 988mg/L, so that the separation of different salts is realized;
step S5: the water in the concentrated water tank is lifted to a first seawater reverse osmosis membrane through a high-pressure pump, the outlet pressure of the high-pressure pump is 61atm, and the inlet waterThe pH value is 8.5, the yield of the produced water is 75 percent, namely the produced water is 75 percent of the inlet water, and the inlet water is 1m3The water yield is 0.75m3The total salt removal rate can be 97%, namely the TDS (total dissolved solids) in the produced water is 3%.
After the treatment process is used for treatment, the concentration of chloride ions in the sodium chloride water tank can reach 2453 mg/L, and the concentration of sulfate ions is 988 mg/L: the concentration of chloride ions in the sodium sulfate water tank is 8312mg/L, and the concentration of sulfate ions can reach 52678 mg/L.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A membrane treatment resource concentration method is characterized by comprising the following steps:
s1, pretreating the wastewater to be treated;
s2, primarily filtering the pretreated wastewater;
s3, separating the wastewater after the primary filtration treatment by using a nanofiltration membrane component to respectively obtain nanofiltration product water and nanofiltration concentrated water;
s4, separating the nanofiltration concentrated water by using a first seawater reverse osmosis membrane component to obtain fresh water and a sodium sulfate solution;
s5, separating the nanofiltration produced water by using a brackish water membrane component and a second seawater reverse osmosis membrane component in sequence to obtain fresh water and a sodium chloride solution;
wherein, the step S4 and the step S5 have no sequential limitation.
2. The membrane treatment resource concentration method according to claim 1, wherein the step S1 specifically comprises: adjusting the pH value of the wastewater to be treated to 6-8, and adding a reducing agent and a scale inhibitor.
3. The membrane treatment resource concentration method according to claim 1, wherein the step S2 specifically comprises: inputting the pretreated wastewater into a cartridge filter for primary filtration, wherein the pressure difference between the outlet and the inlet of the cartridge filter is not more than 10%.
4. The membrane treatment resource concentration method according to claim 1, wherein in the step S3, when the nanofiltration membrane module is used for separation, the water inlet pressure is controlled to be 2-6atm, the temperature is controlled to be 25-40 ℃, and the pH is controlled to be 2-11.
5. The membrane treatment resource concentration method according to claim 1, wherein in the step S4, when the first seawater reverse osmosis membrane module is used for separation, the water inlet pressure is controlled to be 50-70atm, the pH value is controlled to be 7-10, and the yield of produced water is within 75%.
6. The membrane treatment resource concentration method according to claim 1, wherein in the step S5, when the brackish water membrane module is used for separation, the water inlet pressure is controlled to be 2-6atm, the temperature is 15-45 ℃, the pH value is 2-11, and the SDI is not more than 4.
7. The membrane treatment resource concentration method according to claim 1, wherein in the step S5, when the second seawater reverse osmosis membrane module is used for separation, the water inlet pressure is controlled to be 45-50atm, the pH value is controlled to be 7-10, and the yield of produced water is within 80%.
8. The membrane treatment resource concentration method according to claim 1, wherein before the nanofiltration membrane module, the brackish water membrane module, the first seawater reverse osmosis membrane module and the second seawater reverse osmosis membrane module are used for separation, a reducing agent and a scale inhibitor are added into the wastewater.
9. According to any one of claims 2 or 8The membrane treatment resource concentration method is characterized in that the addition amount of the reducing agent is 1-5mg/L, the addition amount of the scale inhibitor is 1-5mg/L, wherein the reducing agent is NaHSO4The scale inhibitor is an organic phosphoric acid scale and corrosion inhibitor.
10. The membrane treatment resource concentration method according to claim 1, wherein before the nanofiltration membrane module, the brackish water membrane module, the first seawater reverse osmosis membrane module and the second seawater reverse osmosis membrane module are used for separation, the wastewater is subjected to chlorination and dechlorination treatment in sequence, and residual chlorine is controlled to be 1mg/L, wherein a reagent used for dechlorination is Na2SO3。
CN202111451129.0A 2021-12-01 2021-12-01 Membrane treatment recycling concentration method Pending CN114149103A (en)

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WO2017181696A1 (en) * 2016-04-21 2017-10-26 广州市心德实业有限公司 Method for treating and recycling brine wastewater containing sodium chloride and sodium sulfate
CN107311381A (en) * 2017-08-21 2017-11-03 国家海洋局天津海水淡化与综合利用研究所 A kind of reverse osmosis concentrated seawater comprehensive utilizing method and system
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WO2017181696A1 (en) * 2016-04-21 2017-10-26 广州市心德实业有限公司 Method for treating and recycling brine wastewater containing sodium chloride and sodium sulfate
CN107311381A (en) * 2017-08-21 2017-11-03 国家海洋局天津海水淡化与综合利用研究所 A kind of reverse osmosis concentrated seawater comprehensive utilizing method and system
CN112408692A (en) * 2019-08-20 2021-02-26 宝武炭材料科技有限公司 Coking wastewater pre-membrane treatment salt-separation zero-discharge process

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Application publication date: 20220308