CN113912226A - Treatment method and application of high-salt-content wastewater - Google Patents

Treatment method and application of high-salt-content wastewater Download PDF

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CN113912226A
CN113912226A CN202010664319.XA CN202010664319A CN113912226A CN 113912226 A CN113912226 A CN 113912226A CN 202010664319 A CN202010664319 A CN 202010664319A CN 113912226 A CN113912226 A CN 113912226A
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membrane
water
salt
purified water
treatment method
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王毅霖
张晓飞
李兴春
杨雪莹
罗臻
李婷
王梓先
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China National Petroleum Corp
CNPC Research Institute of Safety and Environmental Technology Co Ltd
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China National Petroleum Corp
CNPC Research Institute of Safety and Environmental Technology Co Ltd
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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
    • C02F1/44—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
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
    • 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
    • C02F1/445—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by forward 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
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/12—Halogens or halogen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/10—Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]

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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 provides a treatment method and application of high-salt-content wastewater. The total salt content of the high-salt-content wastewater is 10000-30000 mg/L, and the treatment method comprises the following steps: pre-filtering the high-salt-content wastewater to obtain primary purified water, wherein a filtering device adopted in the pre-filtering process is a ceramic membrane or an ultrafiltration membrane, the ceramic membrane is made of silicon carbide, and the ultrafiltration membrane is selected from hydrophilic organic metal membranes; performing a second filtering process on the primary purified water to obtain secondary purified water, wherein a filtering device adopted in the second filtering process is a nanofiltration membrane, and the nanofiltration membrane is made of polyamide; subjecting the second-stage purified water to electrodialysis to obtainPurifying the water. The treatment method provided by the invention is particularly suitable for treating TDS (total salt content) and Cl in sewage discharge indexes‑In restricted areas, the ion concentration in the fresh water effluent can be effectively controlled, the sewage emission reduction capability of oil and gas exploitation and refining enterprises is effectively improved, and the sewage reduction is realized.

Description

Treatment method and application of high-salt-content wastewater
Technical Field
The invention relates to the field of oil and gas exploitation and oil refining chemical industry, in particular to a treatment method of high-salt-content wastewater and application thereof.
Background
The oil gas exploitation and oil refining chemical industry is a water and sewage discharge large house, most of the enterprises are in water shortage areas and watershed water environment sensitive areas, the water consumption cost of the enterprises is continuously improved, the continuous healthy development of the oil gas exploitation and petrochemical industry is also restricted, especially in the areas of Sichuan province, Shanghai city, Beijing city and the like, TDS (total salt content) or chlorine root is added to serve as an index of standard discharge, so that the desalination and concentration technology serves as an important storage technology, the effluent quality can be effectively improved, the sewage reduction is realized, and the sewage treatment cost is reduced.
The oil and gas exploitation and oil refining chemical industry all have waste water with high salt content, such as shale gas produced water, reverse osmosis concentrated water of refining enterprises and the like. At present, the fracturing flow-back fluid is treated simply by simple technologies such as sterilization, chemical flocculation, filtration and the like until the fracturing flow-back fluid is recycled, and part of the sewage which cannot be recycled needs to be transported to a sewage treatment plant for treatment, so that the transportation cost is high. The field lacks a low-cost movable in-situ sewage reduction process. Aiming at reverse osmosis concentrated water of refining enterprises, the enterprises have few independent treatments, and the water quantity occupies a small proportion in the total external discharge capacity, so the reverse osmosis concentrated water is usually mixed and then discharged after reaching the standard.
Conventional desalination techniques are: 1) evaporation technology: such as multiple-effect evaporation technology, mechanical compression evaporation technology and the like, the technology has been developed into a mature seawater desalination technology, solves the problem of serious scaling, is gradually applied to the treatment direction of high salt-containing water, but has high treatment cost all the time; 2) reverse osmosis technology: the salt rejection rate is higher at high flow rate, the separation of materials can be realized at medium and low operation pressure, the product water quality is better, the technical development is mature, engineering cases are provided in the fields of chemical engineering and seawater desalination, but the requirement of reverse osmosis on the quality of inlet water is relatively high; 3) nanofiltration technology: the membrane separation technology is a low-pressure reverse osmosis membrane, takes pressure difference as driving force, has a membrane aperture between reverse osmosis and ultrafiltration, can intercept particles with the particle size of nanometer level in water, and has the advantages of lower operating pressure and lower energy consumption than reverse osmosis, but the interception effect of the membrane on molecules is not as good as that of reverse osmosis; 4) forward osmosis technology: the chemical potential difference of water in the solution on the two sides of the membrane is utilized to separate substances, no external pressure is needed, the pollution to the membrane is less, and the energy consumption is lower. However, the lack of forward osmosis membranes with high water flux, high salt rejection and superior mechanical properties and the high osmotic pressure and easy-to-recover draw solution are major obstacles limiting their industrial application. 5) Electro-adsorption technology: the method is a process that under the action of an external voltage, the surface of an electrode is charged, ions in sewage move to the surface of the electrode to form an electric double layer, and the concentration of the ions in effluent is reduced. The technology has the advantages of low energy consumption, reproducibility, no need of adding chemical reagents, no secondary pollution, high desalting efficiency and suitability for sewage treatment with low salt content. 6) A cold crystallization method: the basic principle is to cool the hot solution with high salt content (or saturated salt), which is that the salt solution has high salt purity because the temperature is reduced and the solubility is reduced to separate out crystalline salt. The basic principle of the method is not easy to see, the method is only suitable for the salt with the solubility sensitive to the temperature, the process energy consumption and the occupied area are large, and the production efficiency is low.
The electrodialysis technology is widely applied to water treatment, and under the action of a direct current electric field, the electrolyte is separated from the solution by taking potential difference as power and utilizing the selective permeability of an ion exchange membrane, so that the concentration, desalination, refining and purification of the solution are realized. The electrodialysis technology has the advantages of simple operation, simple equipment, good water outlet effect and the like, but also has the defects of easy membrane pollution, large workload of overhaul and maintenance, small water treatment amount, capability of only removing charged ions and poor anti-scaling performance.
Disclosure of Invention
The invention mainly aims to provide a treatment method of high-salt-content wastewater and application thereof, and aims to solve the problems of easy membrane pollution, large overhaul workload, small treatment water amount, removal of charged ions only and poor anti-scaling performance of the existing electrodialysis technology.
In order to achieve the above object, one aspect of the present invention provides a method for treating high-salinity wastewater, wherein the total salinity of the high-salinity wastewater is 10000-30000 mg/L, and the method comprises: pre-filtering the high-salt-content wastewater to obtain primary purified water, wherein a filtering device adopted in the pre-filtering process is a ceramic membrane or an ultrafiltration membrane, the ceramic membrane is made of silicon carbide, and the ultrafiltration membrane is selected from hydrophilic organic metal membranes; performing a second filtering process on the primary purified water to obtain secondary purified water, wherein a filtering device adopted in the second filtering process is a nanofiltration membrane, and the nanofiltration membrane is made of polyamide; and performing electrodialysis process on the secondary purified water to obtain purified water.
Furthermore, the aperture of the ceramic membrane is 40-50 nm, and the effective filtering area is 0.43-0.56 m2The number of the membrane channels is 19-37, and the running flow rate is 2.5-4 m/s.
Furthermore, the aperture of the ultrafiltration membrane is 2-5 nm, and the effective membrane area is 0.8-1.9 m2The membrane flux is 20-200L/m2/h。
Furthermore, the aperture of the nanofiltration membrane is 1-2 nm, and the effective membrane area is 1.1-1.9 m2。
Further, the membrane module adopted in the electrodialysis process is a homogeneous membrane, the number of membrane stack is 25, the polar liquid in the electrodialysis process is selected from sodium sulfate, and the flow rate is 400-1000L/h.
Further, the processing method further comprises: when the concentration of ions with the valence more than or equal to 2 in the high-salt-content wastewater is lower than 800mg/L, directly performing a second filtering process on the high-salt-content wastewater without performing a pre-filtering process to obtain secondary purified water.
Further, the processing method further comprises: performing a backwashing process on the ceramic membrane, wherein the backwashing process is water-gas combined backwashing; preferably, in the backwashing process, the frequency of air backwashing is 5-10 s/time, and the frequency of water backwashing is 10-20 s/time.
The application also provides application of the treatment method in the fields of oil and gas exploitation and oil refining chemical industry.
According to the technical scheme, before the electrodialysis step, the ceramic membrane or the ultrafiltration organic membrane and the nanofiltration membrane are adopted to carry out the pretreatment process and the second filtration process on the high-salt-content wastewater in sequence, so that the anti-scaling performance of the device in the electrodialysis process can be greatly improved. The secondary purified water is moderately concentrated by electrodialysis, so that sewage reduction treatment is realized, the treatment scale of subsequent mechanical compression evaporation and multiple-effect evaporation processes is effectively reduced, and the investment cost is reduced. Meanwhile, the ceramic membrane, the ultrafiltration membrane and the nanofiltration membrane are limited in the range, so that the purification effect of the finally obtained purified water can be improved. The treatment method provided by the invention is particularly suitable for treating TDS (total salt content) and Cl in sewage discharge indexes-In restricted areas, the ion concentration in the fresh water effluent can be effectively controlled, the sewage emission reduction capability of oil and gas exploitation and refining enterprises is effectively improved, and the sewage reduction is realized.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 shows a block flow diagram of a process for treating high salinity wastewater provided in accordance with an exemplary embodiment of the present invention;
FIG. 2 shows a process flow diagram of the pretreatment process provided in example 1 of the present invention;
FIG. 3 shows a process flow diagram of a second filtration process provided in example 1 of the present invention;
figure 4 shows a process flow diagram of an electrodialysis process as provided in example 1 of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
As described in the background art, the existing electrodialysis technology has the problems of easy membrane pollution, large overhauling workload, small water treatment amount, only removal of charged ions and poor anti-scaling performance. In order to solve the technical problem, the application provides a treatment method of high-salt wastewater, wherein the total salt content TDS of the high-salt wastewater is 10000-30000 mg/L, and the treatment method comprises the following steps: pre-filtering the high-salt-content wastewater to obtain primary purified water, wherein a filtering device adopted in the pre-filtering process is a ceramic membrane or an ultrafiltration membrane, the ceramic membrane is made of silicon carbide, and the ultrafiltration membrane is a hydrophilic organic metal membrane; performing a second filtering process on the primary purified water to obtain secondary purified water, wherein a filtering device adopted in the second filtering process is a nanofiltration membrane, and the nanofiltration membrane is made of polyamide; and performing electrodialysis process on the secondary purified water to obtain purified water.
In the wastewater treatment method, before the electrodialysis step, a ceramic membrane or an ultrafiltration organic membrane and a nanofiltration membrane are adopted to carry out a pretreatment process and a second filtration process on the high-salt-content wastewater in sequence, so that the anti-scaling performance of the device in the electrodialysis process can be greatly improved. The secondary purified water is moderately concentrated by electrodialysis, so that sewage reduction treatment is realized, the treatment scale of subsequent mechanical compression evaporation and multiple-effect evaporation processes is effectively reduced, and the investment cost is reduced. Meanwhile, the ceramic membrane, the ultrafiltration membrane and the nanofiltration membrane are limited in the range, so that the purification effect of the finally obtained purified water can be improved. The treatment method provided by the invention is particularly suitable for treating TDS (total salt content) and Cl in sewage discharge indexes-In restricted areas, the ion concentration in the fresh water effluent can be effectively controlled, and the oil gas exploitation and refining can be effectively improvedThe sewage discharge reduction capability of enterprises and the sewage reduction can be realized.
The pre-filtration process adopts two modes, and the user can select an ultrafiltration mode or a ceramic membrane mode according to the requirement. Good reaction conditions can be created for the subsequent desalting process through the pretreatment process, the filtration of suspended matters, oil, microorganisms and other substances is effectively realized, the solid suspended matters in the primary purified water after the treatment are not detected, the oil is less than 2mg/L, and the sludge density index SDI is less than 3 mg/L.
The hydrophilic organic metal film preferably has a pore diameter of 5nm and an effective film area of 1m2The membrane flux is 20-200L/m2The organic metal polymer film of the manufacturer is water planet, and the model is Titan70XB-2540-90 HS; the polyamide membrane preferably has a pore diameter of 1.2nm and an effective membrane area of 1.8m2A modified polyamide membrane manufactured by koch with model number 2538-SR 4.
In a preferred embodiment, the ceramic membrane has a pore size of 40-50 nm and an effective filtration area of 0.43-0.56 m2The number of the membrane channels is 19-37, and the running flow rate is 2.5-4 m/s. The pore size, molecular cut-off, effective filtration area and the number of membrane channels of the ceramic membrane include, but are not limited to, the above ranges, and the limitation thereof is advantageous for further improving the purification effect of the pre-filtration process.
In a preferred embodiment, the ultrafiltration membrane has a pore size of 2 to 5nm and an effective membrane area of 0.8 to 1.9m2The membrane flux is 20-200L/m2H is used as the reference value. The pore size, molecular cut-off, effective filtration area and the number of membrane channels of the ultrafiltration membrane include, but are not limited to, the above ranges, and the limitation thereof is advantageous for further improving the purification effect of the pre-filtration process.
In the second filtering process, the filtering objects of the nanofiltration membrane are monovalent ions and divalent ions. In a preferred embodiment, the aperture of the nanofiltration membrane is 1-2 nm, and the effective membrane area is 1.1-1.9 m2. The pore size and effective filtration area of the nanofiltration membrane include, but are not limited to, the above ranges, and the limitation thereof is advantageous in further improving the purification effect of the second filtration process.
In a preferred embodiment, the membrane module used in the electrodialysis process is a homogeneous membrane, the number of membrane stack is 25, the polar liquid in the electrodialysis process includes but is not limited to sodium sulfate, and the flow rate is 400-1000L/h. The type and flow rate of the polar liquid in the electrodialysis process include, but are not limited to, the above range, and the limitation to the above range is advantageous for further improving the purification effect of the electrodialysis process.
The ultrafiltration organic membrane is preferably a roll type organic metal hydrophilic membrane with excellent oil stain resistance according to the water quality characteristics of industrial sewage, and the adoption of the hydrophilic organic metal membrane is beneficial to improving the removal efficiency of organic matters in the pretreatment process. In a preferred embodiment, the hydrophilic organometallic film is an organometallic polymer film. Compared with polyvinylidene fluoride (PVDF) membranes, the organic metal membrane has the advantages that pollutants on the membrane can be removed only by half of backwashing and cleaning processes, so that the higher flux can be continuously maintained, and the organic metal membrane is favorable for further improving the content of organic matters in primary purified water.
In a preferred embodiment, the processing method further includes: when the concentration of ions with the valence more than or equal to 2 in the high-salt-content wastewater is lower than 800mg/L, directly performing a second filtering process on the high-salt-content wastewater without performing a pretreatment process to obtain secondary purified water.
In a preferred embodiment, the processing method further includes: performing a backwashing process on the ceramic membrane, wherein the backwashing process is water-gas combined backwashing; preferably, in the backwashing process, the frequency of air backwashing is 5-10 s/time, and the frequency of water backwashing is 10-20 s/time.
In a preferred embodiment, the above treatment method further comprises on-line detection of pH and conductivity of the primary and final purified water to control the duration of aeration and backwash frequency and the time of the electrodialysis process.
In a preferred embodiment, the treatment method further comprises controlling the pretreatment process, the second filtration process and the electrodialysis process by using a PLC control system, and the three processes can be operated independently.
The application also provides application of the treatment method in the fields of oil and gas exploitation and oil refining chemical industry.
In the wastewater treatment method, before the electrodialysis step, a ceramic membrane or an ultrafiltration organic membrane and a nanofiltration membrane are adopted to carry out a pretreatment process and a second filtration process on the high-salt-content wastewater in sequence, so that the anti-scaling performance of the device in the electrodialysis process can be greatly improved. The secondary purified water is moderately concentrated by electrodialysis, so that sewage reduction treatment is realized, the treatment scale of subsequent mechanical compression evaporation and multiple-effect evaporation processes is effectively reduced, and the investment cost is reduced. Meanwhile, the ceramic membrane, the ultrafiltration membrane and the nanofiltration membrane are limited in the range, so that the purification effect of the finally obtained purified water can be improved. By adopting the treatment process, the water quality of the TDS of the effluent meets the requirement of local discharge water quality, the high-salinity water is moderately concentrated and highly concentrated, the subsequent near-zero discharge process scale is reduced, and a new technical scheme is provided for improving the water resource utilization rate, realizing sewage reduction and reaching the standard discharge in oil and gas exploitation and oil refining chemical industry.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
Example 1
The flow block diagram of the treatment process of the gas field produced water with the TDS concentration of 30000mg/L, the hardness of 800mg/L, suspended matters of 110mg/L and petroleum of 100mg/L and the high-salt-content wastewater in the embodiment is shown in the figure 1.
S1, as shown in figure 2, in the ceramic membrane operation mode, the solenoid valve is opened, and the water inlet lift pump is started after 5S. Lifting the sewage to be treated to a raw water tank, and when the liquid level in the raw water tank reaches a high liquid level, automatically starting a ceramic membrane circulating pump by a liquid level switch to start a ceramic membrane (the aperture of the ceramic membrane is 40nm, and the effective filtering area is 0.43 m)2The number of membrane channels was 19. Silicon carbide, dijie Hubei, model DJSC-40/19/6/1200) to obtain primary purified water; circulating water flows back to the raw water tank, and the primary purified water enters the water production tank or the backwashing water tank and partially flows back to the ultrafiltration raw water tank.
S2, the water produced in the step S1 enters the knotAnd operating the scale ion separation membrane system. As shown in fig. 3, a nanofiltration water inlet lift pump is started, a nanofiltration water supply pump is started under the control of a liquid level switch when a nanofiltration raw water tank reaches a high liquid level, the nanofiltration high pressure pump is automatically started after 3s, and the water passes through a nanofiltration membrane element (the aperture of the nanofiltration membrane is 1.2nm, and the effective membrane area is 1.8 m)2The material is special modified polyamide, the manufacturer is Koch, the model is 2538-SR4), a second filtering process is carried out to obtain secondary purified water, the circulating water flows back into the nanofiltration raw water tank, and the secondary purified water enters the nanofiltration water production tank or the backwashing water tank or partially flows back into the nanofiltration raw water tank. And water in the backwashing tank is used for backwashing the nanofiltration membrane component through the cleaning pump.
S3, feeding the water (second-stage purified water) produced in the step S2 into an electrodialysis unit (membrane material is homogeneous membrane, manufacturer is Nippon Dongli, model number is 280 x 560mm, polar liquid in the electrodialysis process is selected from sodium sulfate, and flow rate is 1m3H). As shown in fig. 4, the electrodialysis water inlet lift pump is started, the water to be treated enters the concentration chamber tank and the diluting chamber tank, and high and low liquid level switches are respectively arranged in the diluting chamber tank and the concentration chamber tank. The liquid level switch and the intake lift pump are interlocked, the high liquid level stops the pump, the low liquid level starts the pump, and the two circulating pumps which are correspondingly matched with the dense chamber tank and the dilute chamber tank are started, when a certain liquid level reaches the high liquid level, the corresponding circulating pump is started, and the other circulating pump is started in an interlocked manner. Under the action of the circulating pump, the polar water in the polar water tank is firstly conveyed to the electrodialysis membrane stack, and the polar water obtained after electrodialysis is discharged or reflows to the polar water tank. As the plant operates, the in-line conductivity in the rich and lean chambers changes. The details are as follows:
the incoming water TDS concentration of the high saline water wastewater is 30000mg/L, the hardness is 800mg/L, the suspended matter is 110mg/L, the petroleum is 100mg/L and the high saline water wastewater continuously runs, and aims to reduce the TDS to be less than 1500mg/L and reduce the hardness to be 40 mg/L. The treatment method of the high-salt-content wastewater comprises the following steps: the polar chamber is filled with 1.5% Na2SO4Solution (for conduction); the circulation flow rate was set to 1000L/h.
After the operation is carried out for 1 hour, the temperature rises by about 4-5 ℃, and the rise is not obvious. It was confirmed that the heat exchanger does not have to be started if the operation is performed for a short time, and the heat exchanger needs to be started if the operation is performed for a long time.
The experiment is run for 58min, the desalted solution is reduced to 1.13mS/cm, and the conductivity of the concentrated solution is 45.9 mS/cm. The voltage of the film stack is 18.4V, the voltage of the film pair is 0.736V, and the average current density is 45.9A/m2The effluent quality can reach the requirement that TDS is less than 1500mg/L, and meets the local discharge standard.
During the period, the effluent water of the first filtration process is detected to be 5mg/L of suspended matters and 0.1mg/L of petroleum. And aiming at the effluent (secondary purified water) in the second filtering process, detecting that the hardness of the effluent is reduced to 8mg/L by using a rapid detection kit, and treating the effluent by using an electrodialysis membrane to ensure that the hardness of the effluent in fresh water is less than 4 mg/L. The concentration multiple ratio of the fresh water to the concentrated water is more than 40.
Example 2
The water quality of the gas field produced water in the embodiment is that the TDS concentration is 30000mg/L, the hardness is 800mg/L, the suspended matters are 110mg/L, and the petroleum is 100 mg/L.
The differences from example 1 are:
an ultrafiltration membrane (with a pore diameter of 5nm and an effective membrane area of 1 m) is used in the pre-filtration process2The membrane flux is 20-200L/m2The material is organic metal polymer film, the manufacturer is water planet, the model is Titan70XB-2540-90HS), and the filtration is carried out to replace ceramic film filtration.
The experiment is run for 56min, the desalted solution is reduced to 1.08mS/cm, and the conductivity of the concentrated solution is 45.9 mS/cm. The voltage of the film stack is 18.4V, the voltage of the film pair is 0.736V, and the average current density is 45.9A/m2The effluent quality can reach the requirement that TDS is less than 1500mg/L, and meets the local discharge standard.
During the period, the effluent water of the first filtration process is detected to have suspended matters less than 11mg/L and petroleum less than 10.06 mg/L. And the water inlet with better water quality is provided for the subsequent electrodialysis process. And (3) detecting the hardness of the effluent (secondary purified water) in the second filtering process from 34mg/L by using a rapid detection kit, wherein the hardness of the effluent in the fresh water is less than 4mg/L after the effluent is treated by an electrodialysis membrane. The concentration multiple ratio of the fresh water to the concentrated water is more than 40.
Example 3
The water quality of the gas field produced water in the embodiment is that the TDS concentration is 30000mg/L, the hardness is 2000mg/L, the suspended matters are 100mg/L, and the petroleum is 2.6 mg/L.
The differences from example 2 are:
the inlet water hardness is 2000mg/L, the suspended matters are 100mg/L, and the petroleum is 2.6mg/L
The experiment is run for 1h, the desalted solution is reduced to 0.98mS/cm, and the conductivity of the concentrated solution is 45.8 mS/cm. The voltage of the film stack is 18.4V, the voltage of the film pair is 0.736V, and the average current density is 45.9A/m2The effluent quality can reach the requirement that TDS is less than 1500mg/L, and meets the local discharge standard.
During the period, the effluent water of the first filtration process is detected to have suspended matters less than 1mg/L and petroleum less than 10.06 mg/L. And the water inlet with better water quality is provided for the subsequent electrodialysis process. And aiming at the effluent (secondary purified water) in the second filtering process, detecting that the hardness of the effluent is reduced from 2000mg/L to 24mg/L by using a rapid detection kit, and treating the effluent by using an electrodialysis membrane to ensure that the hardness of the effluent in fresh water is less than 5 mg/L. The concentration multiple ratio of the fresh water to the concentrated water is more than 40.
Example 4
The differences from example 2 are:
the water quality of the refined reverse osmosis concentrated water of the embodiment is that the TDS concentration is 10000mg/L, the hardness is 300mg/L, suspended matters are less than 1mg/L, and petroleum is less than 0.06mg/L
The suspended matters in the inlet water are less than 1mg/L, the petroleum is less than 0.06mg/L, the experiment is switched to span the first filtering unit and directly enters the nanofiltration unit, the hardness of the outlet water is reduced from 300mg/L to 30mg/L through the detection of a rapid detection kit, the experiment is operated for 30min, the desalted liquid is reduced to 1.1mS/cm, and the conductivity of the concentrated solution is 18.8 mS/cm. The voltage of the film stack is 18.4V, the voltage of the film pair is 0.736V, and the average current density is 43A/m2The effluent quality can reach the requirement that TDS is less than 1500mg/L, and meets the local discharge standard. After the treatment of the electrodialysis membrane, the hardness of the fresh water effluent is less than 2 mg/L.
Example 5
The differences from example 1 are: the flow rate of the electrodialysis process was 400L/h.
The experiment is operated for 70min, the desalted solution is reduced to 1.13mS/cm, and the conductivity of the concentrated solution is 45.9 mS/cm. The voltage of the film stack is 18.4V, the voltage of the film pair is 0.736V, and the average current density is 51A/m2The effluent quality can reach the requirement that TDS is less than 1500mg/L, and meets the local discharge standard.
Example 6
The differences from example 1 are: the flow rate of the electrodialysis process was 1400L/h.
The experiment is run for 66min, the desalted solution is reduced to 1.13mS/cm, and the conductivity of the concentrated solution is 45.9 mS/cm. The voltage of the film stack is 18.4V, the voltage of the film pair is 0.736V, and the average current density is 52.2A/m2The effluent quality can reach the requirement that TDS is less than 1500mg/L, and meets the local discharge standard.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
comparing examples 1 and 5 and 6, it is understood that limiting the flow rate of the electrodialysis process within the preferred range of the present application is advantageous in improving the purification efficiency of high-salt wastewater.
Comparing examples 2 and 3, it is known that limiting the process parameters of the ultrafiltration membrane within the preferred ranges of the present application enables better adaptability to high-salinity wastewater with higher hardness and facilitates improvement of purification efficiency of the high-salinity wastewater.
Comparing examples 2 and 4, it can be seen that the process flow designed by the application is selected, and aiming at the water quality specificity of the inlet water, when suspended matters and petroleum in the inlet water are ultralow, the process route is controlled to cross the primary filtration process, and the inlet water can directly enter the nanofiltration process unit, so that the process unit is simplified, and the energy consumption of high-salinity wastewater treatment is reduced.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. The treatment method of the high-salt-content wastewater is characterized in that the total salt content of the high-salt-content wastewater is 10000-30000 mg/L, and comprises the following steps:
pre-filtering the high-salt-content wastewater to obtain primary purified water, wherein a filtering device adopted in the pre-filtering process is a ceramic membrane or an ultrafiltration membrane, the ceramic membrane is made of silicon carbide, and the ultrafiltration membrane is selected from hydrophilic organic metal membranes;
performing a second filtering process on the primary purified water to obtain secondary purified water, wherein a filtering device adopted in the second filtering process is a nanofiltration membrane, and the nanofiltration membrane is made of polyamide;
and carrying out electrodialysis process on the secondary purified water to obtain purified water.
2. The treatment method according to claim 1, wherein the ceramic membrane has a pore size of 40 to 50nm and an effective filtration area of 0.43 to 0.56m2The number of the membrane channels is 19-37, and the running flow rate is 2.5-4 m/s.
3. The treatment method according to claim 1, wherein the ultrafiltration membrane has a pore diameter of 2 to 5nm and an effective membrane area of 0.8 to 1.9m2The membrane flux is 20-200L/m2/h。
4. The method according to claim 2 or 3, wherein the nanofiltration membrane has a pore diameter of 1 to 2nm and an effective membrane area of 1.1 to 1.9m2。
5. The treatment method according to claim 4, wherein the membrane module used in the electrodialysis process is a homogeneous membrane, the number of membrane stack pairs is 25, the polar liquid in the electrodialysis process is selected from sodium sulfate, and the flow rate is 400-1000L/h.
6. The processing method according to claim 5, characterized in that it further comprises: and when the concentration of ions with the valence more than or equal to 2 in the high-salt-content wastewater is lower than 800mg/L, directly performing the second filtering process on the high-salt-content wastewater without performing the pre-filtering process to obtain the secondary purified water.
7. The processing method according to any one of claims 1 to 6, characterized in that it further comprises: performing a backwashing process on the ceramic membrane, wherein the backwashing process is water-gas combined backwashing; preferably, in the backwashing process, the frequency of air backwashing is 5-10 s/time, and the frequency of water backwashing is 10-20 s/time.
8. Use of the treatment method of any one of claims 1 to 7 in the fields of oil and gas production and refinery chemistry.
CN202010664319.XA 2020-07-10 2020-07-10 Treatment method and application of high-salt-content wastewater Pending CN113912226A (en)

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CN114873820A (en) * 2022-05-27 2022-08-09 四川环科美能环保科技有限公司 Treatment process of shale gas fracturing flowback fluid

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CN105000726A (en) * 2015-09-02 2015-10-28 波鹰(厦门)科技有限公司 Method for treating and recycling high-salt oil-field wastewater
CN111115936A (en) * 2019-12-30 2020-05-08 杭州蓝然环境技术股份有限公司 Membrane method treatment process of gallic acid crystallization mother liquor

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Publication number Priority date Publication date Assignee Title
CN105000726A (en) * 2015-09-02 2015-10-28 波鹰(厦门)科技有限公司 Method for treating and recycling high-salt oil-field wastewater
CN111115936A (en) * 2019-12-30 2020-05-08 杭州蓝然环境技术股份有限公司 Membrane method treatment process of gallic acid crystallization mother liquor

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* Cited by examiner, † Cited by third party
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CN114873820A (en) * 2022-05-27 2022-08-09 四川环科美能环保科技有限公司 Treatment process of shale gas fracturing flowback fluid

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