CN113501568A - Multistage low-desalination-rate membrane module high-salinity wastewater concentration system and concentration method thereof - Google Patents
Multistage low-desalination-rate membrane module high-salinity wastewater concentration system and concentration method thereof Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 192
- 239000002351 wastewater Substances 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims abstract description 11
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 154
- 239000012267 brine Substances 0.000 claims abstract description 48
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 48
- 238000010612 desalination reaction Methods 0.000 claims abstract description 33
- 239000012466 permeate Substances 0.000 claims abstract description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000013505 freshwater Substances 0.000 claims abstract description 23
- 238000005265 energy consumption Methods 0.000 claims abstract description 22
- 238000011084 recovery Methods 0.000 claims abstract description 16
- 230000003204 osmotic effect Effects 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 12
- 230000000149 penetrating effect Effects 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 4
- 239000000047 product Substances 0.000 claims description 4
- 159000000000 sodium salts Chemical class 0.000 claims description 4
- 238000001728 nano-filtration Methods 0.000 claims description 3
- 238000000746 purification Methods 0.000 claims description 3
- 125000006850 spacer group Chemical group 0.000 claims description 3
- 238000009941 weaving Methods 0.000 claims description 2
- 238000007599 discharging Methods 0.000 claims 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 abstract description 16
- 239000011780 sodium chloride Substances 0.000 abstract description 10
- 230000035699 permeability Effects 0.000 abstract description 2
- 150000003839 salts Chemical class 0.000 description 21
- 239000000243 solution Substances 0.000 description 9
- 230000002411 adverse Effects 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000010842 industrial wastewater Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- 102000003939 Membrane transport proteins Human genes 0.000 description 1
- 108090000301 Membrane transport proteins Proteins 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000009061 membrane transport Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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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
- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/025—Reverse osmosis; Hyperfiltration
- B01D61/026—Reverse osmosis; Hyperfiltration comprising multiple reverse osmosis steps
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/08—Apparatus therefor
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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
- 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
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Abstract
The invention belongs to the field of water treatment, and particularly relates to a high-salinity wastewater concentration system with a multistage low-desalination rate membrane group and a concentration method thereof, wherein the system mainly adopts a low-desalination reverse osmosis membrane with the desalination rate of 30-75%, and can obtain saline water with higher concentration than that of a traditional reverse osmosis membrane by using the multistage low-desalination reverse osmosis membrane; the brine feed is pressurized by a high-pressure pump before entering a primary reverse osmosis membrane group for generating fresh water, permeate of each next stage of a subsequent intermediate multi-stage reverse osmosis membrane group is repressurized and circulated back to the previous stage to be used as additional feed, the osmotic pressure difference between the high-pressure side and the low-pressure side of the intermediate multi-stage reverse osmosis membrane group is reduced, a smaller applied pressure delta P is given, the brine concentration can be improved, and the multi-stage low-desalination reverse osmosis membrane has lower permeability for repressurization and recirculation in a low desalination rate stage, has lower energy consumption when the number of stages is more, is more energy-saving, and can also improve the recovery rate of the fresh water.
Description
Technical Field
The invention relates to the field of water treatment, in particular to a high-salinity wastewater concentration system with a multistage low-desalination-rate membrane module and a concentration method thereof.
Technical Field
With the continuous development of the industry, as industrial wastewater which is not properly treated is discharged into the environment to bring ecological pollution of water ecology, under the current situation of fresh water shortage, the environmental awareness of people is gradually strengthened, the regulations for managing industrial wastewater are increasingly strict, various industries advocate resource utilization of wastewater, the minimum liquid discharge or zero liquid discharge of wastewater is realized, all water for strengthening wastewater flow is recycled and reused, only solid waste is left, and the wastewater can be treated in a safer and more environment-friendly manner.
In the traditional reverse osmosis, a membrane for treating wastewater has high rejection rate, namely, all pollution factors such as anions and cations, organic matters, suspended matters and the like in a saline water feed flow can be almost intercepted, the water production side of the membrane is almost pure water, and the salt content and other pollutant content of the concentrated water side of the membrane are relatively high, so that the water production side and the concentrated water side form a serious concentration difference; when the concentration difference reaches a certain level, a high-pressure pump is generally required to increase the hydraulic pressure of the brine feed stream, and when the hydraulic pressure exceeds the osmotic pressure of the brine feed stream, water in the brine feed stream permeates through the RO membrane to produce pure product water and concentrated brine; the larger the concentration difference is, the higher the required lift of the high-pressure pump is, and the larger the energy required to be consumed by the treatment system is; however, in practice, when the salt concentration is reached to a certain extent by osmosis, the hydraulic pressure adversely affects the membrane transport performance, and a greater pressure is required, and the pressure-bearing capacity of the reverse osmosis membrane is also affected as the pressure increases, which results in that the concentration of the feed brine cannot be completely completed by one pressurization.
To this end, we have developed a staged or staged desalination process that employs low salt rejection membranes to desalinate or concentrate high salt feed streams, overcoming the hydraulic limitations of conventional reverse osmosis, requiring only moderate hydraulic pressures.
Disclosure of Invention
The invention provides a multistage low-desalination-rate membrane group high-salinity wastewater concentration system and a concentration method thereof, aiming at the current situation that the limitation of brine concentration and osmotic pressure of a reverse osmosis membrane group is difficult to break through in the prior art through pressurization concentration, the hydraulic limitation of conventional reverse osmosis is overcome, only moderate hydraulic pressure is needed, an evaporator is removed after the system is adopted for high-power concentration, the energy consumption is reduced, the obtained final brine can be recycled, the minimum and zero emission of wastewater treatment can be realized, and the harm of the wastewater to the environment is greatly reduced.
In order to achieve the aim, the invention provides a multi-stage low-desalination-rate membrane group high-salinity wastewater concentration system, which utilizes a low-desalination-rate reverse osmosis membrane to realize high-concentration of brine through purification of multi-stage series reverse osmosis membrane groups.
Further, the system apparatus comprises: the system comprises a multistage reverse osmosis membrane group, a high-pressure pump, a primary feed pipe, a cut-off material outflow pipe, a permeate backflow pipe, a fresh water discharge pipe, a final brine pipe and an energy recovery device; the multistage reverse osmosis membrane group is divided into a primary reverse osmosis membrane group, a middle multistage reverse osmosis membrane group and a final reverse osmosis membrane group according to the position of the multistage reverse osmosis membrane group, and each stage of reverse osmosis membrane group is divided into a high-pressure side and a low-pressure side by a reverse osmosis membrane sheet; the high-pressure side of the primary reverse osmosis membrane group is connected with a primary feed pipe, a high-pressure pump is installed on a primary feed pipe section, and a fresh water discharge pipe is arranged on the low-pressure side of the primary reverse osmosis membrane group; the high pressure side of each stage of the middle multistage reverse osmosis membrane group is connected with the high pressure side of the next stage through a cut-off material flow outlet pipe, high-pressure concentrated water of the previous stage is conveyed to the next stage to be used as feeding material, meanwhile, the low pressure side of each stage of the middle multistage reverse osmosis membrane group is connected with the high pressure side of the previous stage through a permeate return pipe, permeate of the low pressure side of the next stage is returned to the high pressure side of the previous stage to be used as additional feeding material, and the permeate return pipe is provided with a high-pressure pump; the low-pressure side of the final-stage reverse osmosis membrane group is connected with the final-stage high-pressure side of the middle multi-stage reverse osmosis membrane group through a permeate return pipe, the high-pressure side of the final-stage reverse osmosis membrane group is connected with a final brine pipe, and an energy recovery device is installed on the final brine pipe.
As one preferable scheme, the primary reverse osmosis membrane group adopts a conventional high-salt rejection reverse osmosis membrane; the middle multistage reverse osmosis membrane group and the final reverse osmosis membrane group adopt reverse osmosis membranes with low desalination rates.
Preferably, the desalination rate of the low desalination rate reverse osmosis membrane is 30-75%, and the concentration ratio of each stage in the multi-stage reverse osmosis membrane group to sodium salt is 1.3-1.55.
As another preferable scheme, the primary reverse osmosis membrane group adopts a conventional high-salt rejection reverse osmosis membrane; the intermediate multi-stage reverse osmosis membrane group and the final reverse osmosis membrane group adopt nanofiltration membranes.
Further, the low pressure side of each of the multi-stage permeate membrane modules is provided with a net-like spacer support membrane of a densely woven structure to maintain the channel geometry.
Meanwhile, the invention also provides a method for concentrating the high-salinity wastewater of the multistage low-desalination-rate membrane module, wherein the liquid to be concentrated is connected with the high-pressure side of the primary reverse osmosis membrane module through the primary feed pipe and is pressurized through a high-pressure pump arranged on the primary feed pipe section, the low-pressure side of the primary reverse osmosis membrane module is provided with a fresh water discharge pipe, and finally the obtained fresh water is discharged; the high pressure side of each membrane group of the middle multistage reverse osmosis membrane group conveys the cut-off substances to the high pressure side of the next stage of reverse osmosis membrane group through the cut-off substance outflow pipe to be used as feed, and the low pressure side of each stage of reverse osmosis membrane group pressurizes the penetrating fluid through a penetrating substance backflow pipe and then circulates to the high pressure side of the previous stage of reverse osmosis membrane group through a high pressure pump on the penetrating substance backflow pipe; the low-pressure side of the final stage reverse osmosis membrane group is connected with the final stage high-pressure side of the middle multi-stage reverse osmosis membrane group through a permeate return pipe, final stage brine is discharged through a final stage brine pipe on the high-pressure side of the final stage reverse osmosis membrane group, and mechanical energy is recovered from the final stage brine through an energy recovery device on the final stage brine pipe.
Further, the energy consumption SEC of the Nth stage in the multistage reverse osmosis membrane group is the product of the ratio of the permeation flow of the Nth stage to the flow of the produced fresh water in the system and the applied pressure delta P; total energy consumption SCE in a systemGeneral assemblyIs the sum of the energy consumption SEC of each stage.
Furthermore, the pressure delta P applied by each stage in the multi-stage reverse osmosis membrane group is less than or equal to 70 bar.
Furthermore, through the continuous concentration of the multistage reverse osmosis membrane group, the limit of the brine concentration and the osmotic pressure of the reverse osmosis membrane group can be broken through, the high brine concentration of 4mol/l of final brine is realized under low energy consumption and medium hydraulic pressure, and the recovery rate of water reaches 95%.
The scheme of the invention has the beneficial effects that: the system mainly adopts a low-desalination reverse osmosis membrane with the desalination rate of 30-75%, the concentration multiplying power of each level in a multi-level reverse osmosis membrane group to sodium salt is 1.3-1.55, so that the obtained penetrating fluid is saline with non-zero osmotic pressure, and the saline with higher concentration than that of the traditional reverse osmosis membrane can be obtained by using the multi-level low-desalination reverse osmosis membrane under the condition of giving a certain applied pressure delta P; the brine feed is pressurized by a high-pressure pump before entering a primary reverse osmosis membrane group for generating fresh water, and the permeate of each next stage of the subsequent intermediate multi-stage reverse osmosis membrane group is repressurized and circulated back to the previous stage to be used as additional feed, so that the osmotic pressure difference between the high pressure side and the low pressure side of the intermediate multi-stage reverse osmosis membrane group is reduced, a smaller applied pressure delta P is given, the brine concentration can be improved, meanwhile, the multi-stage low-desalination reverse osmosis membrane has lower energy consumption due to lower permeability for repressurization and recirculation in the low desalination rate stage, and is more energy-saving, and the system can also improve the recovery rate of the fresh water.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, the drawings in the following description are only one embodiment of the present invention, and it is obvious for a person skilled in the art that other drawings can be obtained without creative efforts.
FIG. 1 is a schematic diagram of a multistage low desalination reverse osmosis membrane module of the present invention;
wherein, 1, a multistage reverse osmosis membrane group; 2. a high pressure pump; 3. a primary feed pipe; 4. a cut-off logistics outlet pipe; 5. a permeate return conduit; 6. a fresh water discharge pipe; 7. a final brine pipe; 8. an energy recovery device; 9. a high pressure side; 10. a low pressure side; 101. a primary reverse osmosis membrane module; 102. the middle multi-stage reverse osmosis membrane group; 103. and (4) a final reverse osmosis membrane group.
Detailed Description
In order to make the technical solutions in the embodiments of the present application better understood, the following description clearly and completely describes the technical solutions in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without making creative efforts based on the embodiments in the present application shall fall within the protection scope of the present application.
As shown in figure 1, a multi-stage low desalination rate membrane group high salinity wastewater concentration system utilizes a low desalination rate reverse osmosis membrane with the desalination rate of 30% -75%, and realizes high concentration of salt water through purification of multi-stage series reverse osmosis membrane groups.
The system device comprises: the system comprises a multistage reverse osmosis membrane group 1, a high-pressure pump 2, a primary feed pipe 3, a cut-off material outflow pipe 4, a permeate return pipe 5, a fresh water discharge pipe 6, a final brine pipe 7 and an energy recovery device 8; the multistage reverse osmosis membrane group 1 is divided into a primary reverse osmosis membrane group 101, a middle multistage reverse osmosis membrane group 102 and a final reverse osmosis membrane group 103 according to the positions of the multistage reverse osmosis membrane group, and each stage of reverse osmosis membrane group is divided into a high-pressure side 9 and a low-pressure side 10 by a reverse osmosis membrane sheet; the high-pressure side of the primary reverse osmosis membrane group is connected with a primary feeding pipe, a high-pressure pump 2 is installed on a primary feeding pipe section, and a fresh water discharge pipe 6 is arranged on the low-pressure side 10 of the primary reverse osmosis membrane group 101; the high pressure side 9 of each stage of the middle multistage reverse osmosis membrane group 102 is connected with the high pressure side 9 of the next stage through a cut-off material outflow pipe 4, high-pressure concentrated water of the previous stage is conveyed to the next stage to be used as feeding material, meanwhile, the low pressure side 10 of each stage of the middle multistage reverse osmosis membrane group 102 is connected with the high pressure side 9 of the previous stage through a permeate return pipe 5, permeate of the low pressure side 10 of the next stage is returned to the high pressure side 9 of the previous stage to be used as additional feeding material, and the permeate return pipe 5 is provided with a high pressure pump 2; the low-pressure side 10 of the final stage reverse osmosis membrane group 103 is connected with the final stage high-pressure side 9 of the middle multi-stage reverse osmosis membrane group 102 through a permeate return pipe 5, the high-pressure side 9 of the final stage reverse osmosis membrane group 103 is connected with a final stage brine pipe 7, and an energy recovery device 8 is installed on the final stage brine pipe 7.
The primary reverse osmosis membrane group 101 adopts a conventional reverse osmosis membrane with high salt rejection rate, namely fresh water is generated in a primary stage; the intermediate multi-stage reverse osmosis membrane group and the final reverse osmosis membrane group adopt reverse osmosis membranes with low salt rejection rates of 30% -75%, salt water permeation is caused by the low salt rejection rate of the reverse osmosis membranes, for given applied pressure, the lower salt rejection rate can cause higher salt permeate, and the osmotic pressure of final salt water is higher along with the increase of osmotic pressure concentration, so that the salt water concentration is higher, and the concentration effect is achieved.
The primary reverse osmosis membrane group adopts a conventional high-salt rejection reverse osmosis membrane; the intermediate multi-stage reverse osmosis membrane group and the final reverse osmosis membrane group adopt nanofiltration membranes.
The desalination rate of the low desalination rate reverse osmosis membrane is 30-75%, and the concentration ratio of each stage in the multi-stage reverse osmosis membrane group to sodium salt is 1.3-1.55. The low-pressure side of each stage of the multi-stage osmotic membrane group is provided with a reticular spacer support membrane with a dense weaving structure so as to maintain the channel geometry and reduce the adverse effect of pressurization on the membrane performance.
Meanwhile, the invention also provides a concentration method of the high-salinity wastewater of the multistage low-desalination-rate membrane module, which comprises the following steps: the liquid to be concentrated is connected with the high-pressure side of the primary reverse osmosis membrane group through the primary feeding pipe, the liquid is pressurized through a high-pressure pump arranged on the primary feeding pipe section, a fresh water discharge pipe is arranged on the low-pressure side of the primary reverse osmosis membrane group, and finally obtained fresh water is discharged; the high pressure side of each membrane group of the middle multistage reverse osmosis membrane group conveys the cut-off substances to the high pressure side of the next stage of reverse osmosis membrane group through the cut-off substance outflow pipe to be used as feed, and the low pressure side of each stage of reverse osmosis membrane group pressurizes the penetrating fluid through a penetrating substance backflow pipe and then circulates to the high pressure side of the previous stage of reverse osmosis membrane group through a high pressure pump on the penetrating substance backflow pipe; the low-pressure side of the final stage reverse osmosis membrane group is connected with the final stage high-pressure side of the middle multi-stage reverse osmosis membrane group through a permeate return pipe, final stage brine is discharged through a final stage brine pipe on the high-pressure side of the final stage reverse osmosis membrane group, and mechanical energy is recovered from the final stage brine through an energy recovery device on the final stage brine pipe.
Energy consumption of the Nth stage in the multistage reverse osmosis membrane moduleSEC is the product of the ratio of the permeate flow in the nth stage to the flow of the produced fresh water in the system and the applied pressure Δ P; total energy consumption SCE in a systemGeneral assemblyIs the sum of the energy consumption SEC of each stage; the pressure delta P applied by each stage in the multi-stage reverse osmosis membrane group is less than or equal to 70 bar.
We modeled the brine feed function at a certain concentration at a certain stage using final brine concentration and specific energy consumption using applied pressure Δ P =70bar, clearly showing that higher brine concentrations C can be achieved when the number of stages of the multistage reverse osmosis membrane module is greaterBAt the same time, for a selected reverse osmosis stage, the energy consumption SEC first decreases with increasing applied pressure Δ P and then increases again, while the salt concentration CBLinearly increasing with increasing applied pressure Δ P; the dependence of the energy consumption SEC on the applied pressure Δ P enables us to find an optimal applied pressure Δ P that will achieve a specific salt concentration CBThe required energy consumption is reduced to the minimum, and the SCE is always consumed by the systemGeneral assemblyIs the sum of the energy consumption SEC of each stage, and for a multi-stage reverse osmosis membrane unit system, the applied pressure delta P and the salt rejection rate of each stage need to be optimized to maximize the performance of the system, namely, the salt concentration C is maximized with the minimum energy consumption SECB(ii) a At the same time, the system can also achieve significantly lower energy consumption SEC over a wide range of feed concentrations.
The continuous concentration of the multi-stage reverse osmosis membrane group can break through the limitation of the brine concentration and the osmotic pressure of the reverse osmosis membrane group, the high brine concentration of 4mol/l of final brine is realized under low energy consumption and medium hydraulic pressure, an evaporator is removed, the energy consumption is reduced, the minimum and zero discharge of wastewater treatment can be realized, the harm of the wastewater to the environment is reduced to the great extent, meanwhile, the recovery rate of water reaches 95%, and the recovery rate of water is defined as the ratio of the produced fresh water to the brine feeding flow.
Taking the design of the membrane of the four-stage reverse osmosis membrane module as an example, the salt rejection of the first-stage membrane is 99.5%, the applied driving pressure is 70bar, the sodium chloride concentration in the treatment solution is concentrated from 5% to 6.5%, the salt rejection of the second-stage membrane is 70%, the applied driving pressure is 70bar, the sodium chloride concentration in the treatment solution is concentrated from 6.5% to 10%, the salt rejection of the third-stage membrane is 50%, the applied driving pressure is 70bar, the sodium chloride concentration in the treatment solution is concentrated from 10% to 15%, the salt rejection of the fourth-stage membrane is 35%, the applied driving pressure is 70bar, the sodium chloride concentration in the treatment solution is concentrated from 15% to 20%, and finally, the system concentrates the sodium chloride solution with the concentration of 5% to 20%.
According to the design of different membrane desalination rates, the system can design reverse osmosis membrane groups with more stages, and meanwhile, the concentration of the sodium chloride solution can be concentrated to be higher.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. The high-salinity wastewater concentration system is characterized in that a low-desalination-rate reverse osmosis membrane is utilized, and the high-salinity wastewater concentration system realizes high-power concentration of brine through purification of multistage series reverse osmosis membrane groups.
2. The system for concentrating high salinity wastewater with multi-stage low desalination membrane module according to claim 1, characterized in that it comprises: the system comprises a multistage reverse osmosis membrane group, a high-pressure pump, a primary feed pipe, a cut-off material outflow pipe, a permeate backflow pipe, a fresh water discharge pipe, a final brine pipe and an energy recovery device; the multistage reverse osmosis membrane group is divided into a primary reverse osmosis membrane group, a middle multistage reverse osmosis membrane group and a final reverse osmosis membrane group according to the position of the multistage reverse osmosis membrane group, and each stage of reverse osmosis membrane group is divided into a high-pressure side and a low-pressure side by a reverse osmosis membrane sheet; the high-pressure side of the primary reverse osmosis membrane group is connected with a primary feed pipe, a high-pressure pump is installed on a primary feed pipe section, and a fresh water discharge pipe is arranged on the low-pressure side of the primary reverse osmosis membrane group; the high pressure side of each stage of the middle multistage reverse osmosis membrane group is connected with the high pressure side of the next stage through a cut-off material flow outlet pipe, high-pressure concentrated water of the previous stage is conveyed to the next stage to be used as feeding material, meanwhile, the low pressure side of each stage of the middle multistage reverse osmosis membrane group is connected with the high pressure side of the previous stage through a permeate return pipe, permeate of the low pressure side of the next stage is returned to the high pressure side of the previous stage to be used as additional feeding material, and the permeate return pipe is provided with a high-pressure pump; the low-pressure side of the final-stage reverse osmosis membrane group is connected with the final-stage high-pressure side of the middle multi-stage reverse osmosis membrane group through a permeate return pipe, the high-pressure side of the final-stage reverse osmosis membrane group is connected with a final brine pipe, and an energy recovery device is installed on the final brine pipe.
3. The system for concentrating high-salinity wastewater by multistage membrane module with low desalination rate as claimed in claim 2, characterized in that the primary reverse osmosis membrane module adopts a conventional reverse osmosis membrane with high salinity rejection rate; the middle multistage reverse osmosis membrane group and the final reverse osmosis membrane group adopt reverse osmosis membranes with low desalination rates.
4. The system for concentrating high-salinity wastewater by using multistage membrane modules with low desalination rate as claimed in claim 3, characterized in that the desalination rate of the reverse osmosis membrane with low desalination rate is 30-75%, and the concentration ratio of each stage in the multistage reverse osmosis membrane module to sodium salt is 1.3-1.55.
5. The system for concentrating high-salinity wastewater by multistage membrane module with low desalination rate as claimed in claim 3, characterized in that the primary reverse osmosis membrane module adopts a conventional reverse osmosis membrane with high salinity rejection rate; the intermediate multi-stage reverse osmosis membrane group and the final reverse osmosis membrane group adopt nanofiltration membranes.
6. The system for concentrating high-salinity wastewater with multistage low-desalination membrane module as claimed in claim 3, characterized in that: the low-pressure side of each stage of the multi-stage osmotic membrane module is provided with a reticular spacer support membrane with a dense weaving structure so as to maintain the channel geometry.
7. A method for concentrating high-salinity wastewater of a multistage low-desalination-rate membrane group is characterized in that a liquid to be concentrated is connected with the high-pressure side of a primary reverse osmosis membrane group through a primary feeding pipe and is pressurized through a high-pressure pump arranged on a primary feeding pipe section, a fresh water discharging pipe is arranged on the low-pressure side of the primary reverse osmosis membrane group, and finally obtained fresh water is discharged; the high pressure side of each membrane group of the middle multistage reverse osmosis membrane group conveys the cut-off substances to the high pressure side of the next stage of reverse osmosis membrane group through the cut-off substance outflow pipe to be used as feed, and the low pressure side of each stage of reverse osmosis membrane group pressurizes the penetrating fluid through a penetrating substance backflow pipe and then circulates to the high pressure side of the previous stage of reverse osmosis membrane group through a high pressure pump on the penetrating substance backflow pipe; the low-pressure side of the final stage reverse osmosis membrane group is connected with the final stage high-pressure side of the middle multi-stage reverse osmosis membrane group through a permeate return pipe, final stage brine is discharged through a final stage brine pipe on the high-pressure side of the final stage reverse osmosis membrane group, and mechanical energy is recovered from the final stage brine through an energy recovery device on the final stage brine pipe.
8. The method for concentrating high-salinity wastewater of multistage low-desalination membrane module according to claim 7, characterized in that: the energy consumption SEC of the Nth stage in the multistage reverse osmosis membrane group is the product of the ratio of the permeation flow of the Nth stage to the flow of the produced fresh water in the system and the applied pressure delta P; total SCE in the SystemGeneral assemblyIs the sum of the energy consumption SEC of each stage.
9. The method for concentrating high-salinity wastewater of multistage low-desalination membrane module according to claim 8, characterized in that: the pressure delta P applied by each stage in the multi-stage reverse osmosis membrane group is less than or equal to 70 bar.
10. The method for concentrating high-salinity wastewater of multistage low-desalination membrane module according to claim 2, characterized in that: through the continuous concentration of the multi-stage reverse osmosis membrane group, the limitation of the brine concentration and the osmotic pressure of the reverse osmosis membrane group is broken through, the high brine concentration of 4mol/l of final-stage brine is realized under low energy consumption and medium hydraulic pressure, and the recovery rate of water reaches 95%.
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| CN114790059A (en) * | 2022-04-11 | 2022-07-26 | 倍杰特集团股份有限公司 | Device and method for concentrating and filtering concentrated water of synthetic ammonia and ethylene glycol wastewater |
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