CN114849487A - Cleaning system and method for ultrafiltration membrane - Google Patents
Cleaning system and method for ultrafiltration membrane Download PDFInfo
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- CN114849487A CN114849487A CN202210618597.0A CN202210618597A CN114849487A CN 114849487 A CN114849487 A CN 114849487A CN 202210618597 A CN202210618597 A CN 202210618597A CN 114849487 A CN114849487 A CN 114849487A
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- 238000000108 ultra-filtration Methods 0.000 title claims abstract description 136
- 239000012528 membrane Substances 0.000 title claims abstract description 113
- 238000004140 cleaning Methods 0.000 title claims abstract description 101
- 238000000034 method Methods 0.000 title claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 230
- 238000004519 manufacturing process Methods 0.000 claims abstract description 57
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims abstract description 55
- 238000011001 backwashing Methods 0.000 claims abstract description 34
- 239000000126 substance Substances 0.000 claims abstract description 19
- 230000006378 damage Effects 0.000 claims abstract description 18
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 11
- 230000003647 oxidation Effects 0.000 claims abstract description 10
- 239000003814 drug Substances 0.000 claims description 53
- 239000002253 acid Substances 0.000 claims description 33
- 239000003795 chemical substances by application Substances 0.000 claims description 26
- 229940079593 drug Drugs 0.000 claims description 18
- 238000001914 filtration Methods 0.000 claims description 13
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 6
- 230000010355 oscillation Effects 0.000 claims description 6
- 238000005201 scrubbing Methods 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 239000005708 Sodium hypochlorite Substances 0.000 claims description 4
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical group [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 3
- 239000003344 environmental pollutant Substances 0.000 claims description 3
- 238000006864 oxidative decomposition reaction Methods 0.000 claims description 3
- 231100000719 pollutant Toxicity 0.000 claims description 3
- 235000006408 oxalic acid Nutrition 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 3
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 16
- 239000007789 gas Substances 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 5
- 239000002033 PVDF binder Substances 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000002427 irreversible effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 150000004676 glycans Chemical class 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002957 persistent organic pollutant Substances 0.000 description 2
- 229920001282 polysaccharide Polymers 0.000 description 2
- 239000005017 polysaccharide Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 102000004169 proteins and genes Human genes 0.000 description 2
- 108090000623 proteins and genes Proteins 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 238000005374 membrane filtration Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
-
- 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
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/145—Ultrafiltration
-
- 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
- C02F1/444—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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/78—Treatment of water, waste water, or sewage by oxidation with ozone
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- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention belongs to the technical field of ultrafiltration membrane cleaning, and discloses a system and a method for cleaning an ultrafiltration membrane. The system comprises a raw water tank, an ultrafiltration water inlet pump, a self-cleaning filter, ultrafiltration equipment, a water production tank, a tail gas destruction device, a backwashing water pump, an air compressor subsystem, an ozone generator subsystem and an optional chemical adding and cleaning subsystem. The novel ultrafiltration membrane system provided by the invention is used in cooperation with the ozone pre-oxidation method, so that the service life of the ultrafiltration membrane can be prolonged, the cleaning effect is improved, and the influence on the online rate of membrane operation is reduced.
Description
Technical Field
The invention belongs to the technical field of ultrafiltration membrane cleaning, and particularly relates to a system and a method for cleaning an ultrafiltration membrane.
Background
The membrane pollution refers to the irreversible change phenomenon of permeation flow and separation characteristics of the membrane caused by the reduction or blockage of the membrane pore diameter caused by adsorption and deposition on the membrane surface or in the membrane pores due to the physical-chemical interaction or mechanical action between particles, colloidal particles or solute macromolecules in water and the membrane in the membrane filtration process. In the field of water treatment, the ultrafiltration membrane is inevitably polluted in normal operation, which is an insurmountable problem for restricting normal water production of the membrane.
At present, physical cleaning and chemical cleaning are commonly used for preventing and treating membrane pollution, various physical cleaning methods such as forward cleaning, reverse cleaning, permeate liquid back pressure cleaning, vibration, water conservancy methods and the like recover certain permeability through cleaning the membrane, but the physical cleaning cannot completely recover the water permeability, and chemical cleaning is also needed. Chemical cleaning is the removal of contaminants from membranes by the reaction of chemical agents with deposits, dirt, corrosion products and other contaminants that affect flux rates and water quality. The method comprises the steps of soaking the membrane in a chemical cleaning solution for a certain time to loosen, decompose and precipitate pollutants on the surface of the membrane.
The common method for preventing and treating the pollution of the ultrafiltration membrane has the following problems:
(1) effect of cleaning on membrane material: the prior organic ultrafiltration membrane material applied to the field of water treatment mainly adopts PVDF material, and the manufacturing process is divided into a solution phase transfer method (NIPS) and a thermal phase separation method (TIPS). The NIPS membrane has the defects of relatively poor chemical stability, low mechanical strength and the like, while the TIPS membrane has the problems of relatively poor chemical stability and relatively poor hydrophilicity although the mechanical strength of the TIPS membrane is improved to a certain extent compared with the NIPS membrane. Due to the above factors, the PVDF membrane is easy to have the conditions of filtration performance reduction or filament breakage and the like caused by membrane corrosion in a conventional membrane cleaning mode, so that the whole service life of the membrane is reduced.
(2) Incomplete cleaning: in both physical cleaning and chemical cleaning, the membrane is cleaned in a restorative manner after the membrane is polluted to a certain degree, and the running water production performance of the ultrafiltration membrane is reduced year by year along with the increase of the service life, which also indicates that the conventional physical or chemical cleaning cannot completely remove the pollution on the membrane and cannot completely clean the membrane.
(3) The cleaning causes the ultrafiltration membrane to have low online running rate: during the operation of the ultrafiltration system, after water is continuously produced for a period of time, backwashing or chemical cleaning is needed to ensure that the water production flux of the membrane is maintained within the design range, and frequent backwashing or chemical cleaning can reduce the water production time of the membrane system and reduce the overall on-line rate of the membrane system.
Therefore, a new system and a method for cleaning an ultrafiltration membrane are urgently needed to be provided aiming at the problems of incomplete cleaning, influence on the online rate of membrane operation and even reduction of the service life of the membrane in the conventional ultrafiltration membrane cleaning technology.
Disclosure of Invention
The invention aims to provide a system and a method for cleaning an ultrafiltration membrane, aiming at the defects of the prior art. The novel ultrafiltration membrane system provided by the invention is used in cooperation with the ozone pre-oxidation method, so that the service life of the ultrafiltration membrane can be prolonged, the cleaning effect is improved, and the influence on the online rate of membrane operation is reduced.
In order to achieve the above object, the present invention provides in a first aspect a system for cleaning an ultrafiltration membrane, the system comprising a raw water tank, an ultrafiltration feed pump, a self-cleaning filter, an ultrafiltration apparatus, a product water tank, a tail gas destruction device, a backwash water pump, an air compressor subsystem and an ozone generator subsystem, and optionally a dosing cleaning subsystem;
the water outlet of the raw water tank, the ultrafiltration water inlet pump, the self-cleaning filter, the ultrafiltration equipment and the water inlet of the water production tank are communicated in sequence; the tail gas destruction device is arranged at the top of the water production tank and is used for recovering ozone entering the water production tank;
the top water production outlet of the ultrafiltration equipment is also communicated with the product water outlet of the water production tank through a back flush water pump; the air compressor subsystem is communicated with a bottom air inlet of the ultrafiltration device;
the ozone generator subsystem comprises a mixer and an ozone generator;
the mixer is arranged between the water outlet of the ultrafiltration water inlet pump and the water inlet of the self-cleaning filter, and the ozone generator is communicated with the mixer; a dosing output pipeline of the dosing cleaning subsystem is communicated with a pipeline between the water outlet of the self-cleaning filter and the bottom water inlet of the ultrafiltration device;
or the mixer is arranged between the water outlet of the backwashing water pump and the top water outlet of the ultrafiltration equipment, and the ozone generator is communicated with the product water inlet of the mixer; and a dosing output pipeline of the dosing cleaning subsystem is communicated with a pipeline between the water outlet of the self-cleaning filter and the water inlet at the bottom of the ultrafiltration device.
According to the present invention, preferably, the raw water tank is further provided with a backwash water inlet and a raw water inlet; the ultrafiltration equipment is also provided with a top backwashing water outlet which is communicated with the backwashing water inlet of the raw water tank.
In the invention, a liquid level meter is arranged in the raw water tank.
According to the present invention, preferably, the chemical feeding and cleaning subsystem includes a chemical feeding box, a chemical feeding pump, an acid feeding box, an acid feeding pump and the chemical feeding output line;
the medicament dosing tank is communicated with the medicament inlet end of the medicament dosing pump;
the acid agent feeding box is communicated with the feeding end of the acid agent feeding pump;
the drug outlet end of the drug adding pump and the drug outlet end of the acid agent adding pump are both communicated with the drug adding output pipeline.
According to the invention, the ultrafiltration membrane is preferably an ultrafiltration membrane comprising polyvinylidene fluoride resin, preferably an ultrafiltration membrane resistant to ozone oxidation known to the person skilled in the art.
According to the invention, preferably, the agent is sodium hypochlorite and/or sodium hydroxide.
According to the present invention, preferably, the acidic agent is at least one of citric acid, oxalic acid and hydrochloric acid.
The second aspect of the invention provides a method for cleaning an ultrafiltration membrane, which adopts the system and comprises the following steps:
s1: conveying the raw water in the raw water tank and ozone to the mixer and the self-cleaning filter together to oxidize and decompose pollutants in the raw water;
s2: conveying the raw water subjected to oxidative decomposition to the ultrafiltration equipment for filtration, then conveying the raw water into the water production tank as product water, and simultaneously recovering and decomposing ozone entering the water production tank through the tail gas destruction device and discharging the ozone out of the system;
s3: and the product water of the water production tank is conveyed to a water production outlet at the top of the ultrafiltration equipment by using the backwashing water pump, membrane wires in the ultrafiltration equipment are backwashed reversely, and meanwhile, the membrane wires in the ultrafiltration equipment are subjected to air oscillation and air bubble scrubbing by the air compressor subsystem.
According to the invention, preferably, in step S1, the adding concentration of the ozone is 6-40 mg/L.
According to the present invention, preferably, the step S3 further includes: and the medicament and/or the acid agent are/is sent to a water inlet at the bottom of the ultrafiltration equipment through the medicament feeding pump and/or the acid agent feeding pump of the medicament feeding and cleaning subsystem according to the membrane pollution condition.
The third aspect of the invention provides a method for cleaning an ultrafiltration membrane, which adopts the system and comprises the following steps:
s1: conveying raw water in the raw water tank to the self-cleaning filter, and performing primary filtration treatment on the raw water;
s2: conveying the raw water subjected to the primary filtration treatment to the ultrafiltration equipment for secondary filtration treatment, and then conveying the raw water into the water production tank to be used as product water;
s3: conveying the product water in the water production tank and the ozone to the mixer and a top water production outlet of the ultrafiltration equipment by using the backwashing water pump, reversely carrying out oxidation backwashing on membrane wires in the ultrafiltration equipment, and simultaneously carrying out air oscillation and bubble scrubbing on the membrane wires in the ultrafiltration equipment by using the air compressor subsystem; and the ozone entering the water production tank is recycled and decomposed by the tail gas destruction device and then discharged out of the system.
According to the present invention, it is preferable that,
in step S3, the adding concentration of the ozone is 6-40 mg/L;
the step S3 further includes: and the medicament and/or the acid agent are sent to a water inlet at the bottom of the ultrafiltration equipment through the medicament feeding pump and/or the acid agent feeding pump of the medicament feeding and cleaning subsystem according to the condition of membrane pollution.
The technical scheme of the invention has the beneficial effects that:
(1) the system for treating the ultrafiltration membrane by using the ozone can reduce irreversible damage to the ultrafiltration membrane and keep the service life of the ultrafiltration membrane. The system is more suitable for treating the ultrafiltration membrane resistant to ozone oxidation, and the membrane is higher in chemical stability and mechanical strength compared with the conventional ultrafiltration membrane and can effectively resist corrosion of membrane cleaning agents such as high-concentration ozone and sodium hypochlorite, so that the system and the method provided by the invention have the advantages that irreversible damage to the membrane is less, cleaning is more thorough, and the influence on the online rate of membrane operation is reduced.
(2) The invention provides an efficient and stable online removal system, which reduces the content of organic matters in the effluent of a membrane system, reduces the operating transmembrane pressure difference of an ultrafiltration membrane, and improves the water permeability of the membrane system, thereby achieving the purposes of reducing the frequency of backwashing and chemical cleaning and improving the overall online rate of the membrane system.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Fig. 1 shows a schematic diagram of a system for cleaning an ultrafiltration membrane according to embodiment 1 of the present invention.
Fig. 2 is a schematic diagram illustrating a system for cleaning an ultrafiltration membrane according to embodiment 2 of the present invention.
Fig. 3 is a graph showing changes in operational data of a membrane system treated by a method for cleaning an ultrafiltration membrane according to example 4 of the present invention.
Fig. 4 shows a variation of operational data of a membrane system treated by the method for cleaning an ultrafiltration membrane according to comparative example 1 of the present invention.
The reference numerals are explained below:
1. a raw water tank; 2. an ultrafiltration water inlet pump; 3. a self-cleaning filter; 4. a mixer; 5. ultrafiltration equipment; 6. a water production tank; 7. backwashing the water pump; 8. a medicament dosing tank; 9. a medicament dosing pump; 10. an acid agent dosing box; 11. an acid dosing pump; 12. an air compressor subsystem; 13. an ozone generator; 14. a tail gas destruction device; 15. a dosing output line; 16. a backwash water inlet; 17. a raw water inlet; 18. a top backwashing water outlet, 19 and a top produced water outlet.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Example 1
The embodiment provides a system for cleaning an ultrafiltration membrane, and as shown in fig. 1, the system comprises a raw water tank 1, an ultrafiltration water inlet pump 2, a self-cleaning filter 3, an ultrafiltration device 5, a water production tank 6, a tail gas destruction device 14, a backwashing water pump 7, an air compressor subsystem 12, an ozone generator subsystem and a dosing cleaning subsystem;
the ozone generator subsystem comprises a mixer 4 and an ozone generator 13;
the water outlet of the raw water tank 1, the ultrafiltration water inlet pump 2, the mixer 4, the self-cleaning filter 3, the ultrafiltration equipment 5 and the water inlet of the water production tank 6 are communicated in sequence; the tail gas destruction device 14 is arranged at the top of the water production tank 6 and is used for recovering ozone entering the water production tank 6;
the ozone generator 13 is communicated with the mixer 4;
the top water production outlet 19 of the ultrafiltration device 5 is also communicated with the product water outlet of the water production tank 6 through a back flush water pump 7; the air compressor subsystem 12 is communicated with the bottom air inlet of the ultrafiltration device 5;
the raw water tank 6 is also provided with a backwashing water inlet 16 and a raw water inlet 17; the ultrafiltration device 5 is also provided with a top backwashing water outlet 18, and the top backwashing water outlet 18 of the ultrafiltration device is communicated with a backwashing water inlet 16 of the raw water tank;
the dosing and cleaning subsystem comprises a medicament dosing tank 8, a medicament dosing pump 9, an acid dosing tank 10, an acid dosing pump 11 and a dosing output pipeline 15; the medicament feeding box 8 is communicated with the medicament feeding end of the medicament feeding pump 9; the acid agent feeding box 10 is communicated with the feeding end of the acid agent feeding pump 11; the drug outlet end of the drug adding pump 9 and the drug outlet end of the acid agent adding pump 11 are both communicated with a pipeline between the water outlet of the self-cleaning filter 3 and the water inlet at the bottom of the ultrafiltration device 5 through the drug outlet pipeline 15;
a liquid level meter (not shown) is arranged in the raw water tank 1.
Example 2
The embodiment provides a system for cleaning an ultrafiltration membrane, and as shown in fig. 2, the system comprises a raw water tank 1, an ultrafiltration water inlet pump 2, a self-cleaning filter 3, an ultrafiltration device 5, a water production tank 6, a tail gas destruction device 14, a backwashing water pump 7, an air compressor subsystem 12, an ozone generator subsystem and a dosing cleaning subsystem;
the water outlet of the raw water tank 1, the ultrafiltration water inlet pump 2, the self-cleaning filter 3, the ultrafiltration equipment 5 and the water inlet of the water production tank 6 are communicated in sequence; the tail gas destruction device 14 is arranged at the top of the water production tank 6 and is used for recovering ozone entering the water production tank 6;
the top water production outlet 19 of the ultrafiltration device 5 is also communicated with the product water outlet of the water production tank 6 through a back flush water pump 7; the air compressor subsystem 12 is communicated with the bottom air inlet of the ultrafiltration device 5;
the ozone generator subsystem comprises a mixer 4 and an ozone generator 13;
the mixer 4 is arranged between the water outlet of the backwashing water pump 7 and the top water outlet 19 of the ultrafiltration device 5, and the ozone generator 13 is communicated with the product water inlet of the mixer 4;
the dosing and cleaning subsystem comprises a medicament dosing tank 8, a medicament dosing pump 9, an acid dosing tank 10, an acid dosing pump 11 and a dosing output pipeline 15; the medicament feeding box 8 is communicated with the medicament feeding end of the medicament feeding pump 9; the acid agent feeding box 10 is communicated with the feeding end of the acid agent feeding pump 11; the drug outlet end of the drug adding pump 9 and the drug outlet end of the acid agent adding pump 11 are communicated with the pipeline between the water outlet of the self-cleaning filter 3 and the water inlet at the bottom of the ultrafiltration device 5 through the drug output pipeline 15.
The raw water tank 1 is also provided with a backwashing water inlet 16 and a raw water inlet 17; the ultrafiltration equipment is also provided with a top backwashing water outlet 18, and the top backwashing water outlet 18 of the ultrafiltration equipment is communicated with the backwashing water inlet 16 of the raw water tank. A liquid level meter (not shown) is arranged in the raw water tank 1.
Example 3
The embodiment provides a method for cleaning an ultrafiltration membrane, which adopts the system described in embodiment 1 and comprises the following steps:
s1: when a liquid level meter detects that the liquid level in a raw water tank 1 reaches a starting liquid level, an ultrafiltration water inlet pump 2 is automatically started, raw water in the raw water tank 1 and ozone from an ozone generator 13 are conveyed to a mixer 4 and a self-cleaning filter 3 together, larger granular impurities in water are primarily filtered, the ozone is fully contacted with organic pollutants in the raw water through the self-cleaning filter 3 and the mixer 4 to generate oxidation reaction, and the organic pollutants are thoroughly decomposed;
the adding concentration of the ozone is 10 mg/L;
s2: conveying the raw water subjected to oxidative decomposition to the ultrafiltration equipment 5 for filtration, then conveying the raw water into the water production tank 6 as product water, and simultaneously recovering and decomposing ozone entering the water production tank 6 into oxygen through the tail gas destruction device 14 and then discharging the oxygen out of the system;
s3: and the product water of the water production tank is conveyed to a top water production outlet 19 of the ultrafiltration equipment by using the backwashing water pump 7, membrane wires in the ultrafiltration equipment 5 are backwashed reversely, and meanwhile, the membrane wires in the ultrafiltration equipment 5 are subjected to air oscillation and air bubble scrubbing by the air compressor subsystem 12.
The ultrafiltration membrane of the embodiment is an ultrafiltration membrane resistant to ozone oxidation.
Example 4
The embodiment provides a method for cleaning an ultrafiltration membrane, which adopts the system described in embodiment 2 and comprises the following steps:
s1: when a liquid level meter detects that the liquid level in a raw water tank 1 reaches a starting liquid level, an ultrafiltration water inlet pump 2 is automatically started, raw water in the raw water tank 1 is conveyed to a self-cleaning filter 3, and the raw water is subjected to primary filtration treatment;
s2: conveying the raw water subjected to the primary filtration treatment to the ultrafiltration equipment 5 for secondary filtration treatment, and then conveying the raw water into the water production tank 6 to be used as product water;
s3: the product water in the water production tank 6 and the ozone are conveyed to the mixer 4 and a top water production outlet 19 of the ultrafiltration device 5 by the back-flushing water pump 7, membrane wires in the ultrafiltration device 5 are reversely subjected to oxidation back-flushing, and meanwhile, the membrane wires in the ultrafiltration device 5 are subjected to air oscillation and air bubble scrubbing by the air compressor subsystem 12; and the ozone entering the water production tank 6 is recycled and decomposed by the tail gas destruction device 14 and then discharged out of the system.
The adding concentration of the ozone is 10 mg/L.
The ultrafiltration membrane of the embodiment is an ultrafiltration membrane resistant to ozone oxidation.
Example 5
This example provides a method for cleaning an ultrafiltration membrane, and the only difference between this example and example 4 is that:
the step S3 further includes: and the medicament and the acid agent are sent to a water inlet at the bottom of the ultrafiltration equipment through the medicament feeding pump 9 and the acid agent feeding pump 11 of the medicament feeding and cleaning subsystem.
The medicament is sodium hypochlorite.
Comparative example
The comparative example provides a method for cleaning an ultrafiltration membrane, and the comparative example is different from the example 4 only in that: instead of reversely carrying out oxidation back washing on the membrane wires in the ultrafiltration device 5 by using ozone, the back washing water pump 7 is only used for conveying the product water in the water production tank 6 to the top water production outlet 19 of the ultrafiltration device 5, and reversely carrying out back washing on the membrane wires in the ultrafiltration device 5.
Test example
This test example compares the COD, polysaccharide and protein removal rates and transmembrane pressure difference of the ultrafiltration membrane cleaning methods of example 4 and comparative example 1, and the results are shown in table 1, fig. 3, and 4, respectively.
TABLE 1
The analysis of the table 1 shows that the invention can reduce the content of COD, polysaccharide and protein in the produced water of the ultrafiltration system, so that the system is in a high-efficiency and stable running state.
Through analysis of figures 3 and 4, the invention can reduce the average operation transmembrane pressure of the membrane system by over 8kpa under the condition of keeping constant flow water production.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. A system for cleaning an ultrafiltration membrane is characterized by comprising a raw water tank, an ultrafiltration water inlet pump, a self-cleaning filter, ultrafiltration equipment, a water production tank, a tail gas destruction device, a backwashing water pump, an air compressor subsystem, an ozone generator subsystem and an optional chemical adding and cleaning subsystem;
the water outlet of the raw water tank, the ultrafiltration water inlet pump, the self-cleaning filter, the ultrafiltration equipment and the water inlet of the water production tank are communicated in sequence; the tail gas destruction device is arranged at the top of the water production tank and used for recovering ozone entering the water production tank;
the top water production outlet of the ultrafiltration equipment is also communicated with the product water outlet of the water production tank through a back flush water pump; the air compressor subsystem is communicated with a bottom air inlet of the ultrafiltration device;
the ozone generator subsystem comprises a mixer and an ozone generator;
the mixer is arranged between the water outlet of the ultrafiltration water inlet pump and the water inlet of the self-cleaning filter, and the ozone generator is communicated with the mixer; a dosing output pipeline of the dosing cleaning subsystem is communicated with a pipeline between the water outlet of the self-cleaning filter and the bottom water inlet of the ultrafiltration device;
or the mixer is arranged between the water outlet of the backwashing water pump and the top water outlet of the ultrafiltration equipment, and the ozone generator is communicated with the product water inlet of the mixer; and a dosing output pipeline of the dosing cleaning subsystem is communicated with a pipeline between the water outlet of the self-cleaning filter and the water inlet at the bottom of the ultrafiltration device.
2. The system for cleaning the ultrafiltration membrane according to claim 1, wherein the raw water tank is further provided with a backwash water inlet and a raw water inlet; the ultrafiltration equipment is also provided with a top backwashing water outlet which is communicated with the backwashing water inlet of the raw water tank.
3. The ultrafiltration membrane cleaning system of claim 1, wherein the dosing cleaning subsystem comprises a drug dosing tank, a drug dosing pump, an acid dosing tank, an acid dosing pump, and the dosing output line.
4. The system for cleaning an ultrafiltration membrane according to claim 3,
the medicament dosing tank is communicated with the medicament inlet end of the medicament dosing pump;
the acid agent feeding box is communicated with the feeding end of the acid agent feeding pump;
the drug outlet end of the drug adding pump and the drug outlet end of the acid agent adding pump are both communicated with the drug adding output pipeline.
5. The system for cleaning an ultrafiltration membrane according to claim 4,
the medicament is sodium hypochlorite and/or sodium hydroxide;
the acid agent is at least one of citric acid, oxalic acid and hydrochloric acid.
6. A method for cleaning an ultrafiltration membrane, the method using the system of any one of claims 1 to 5, comprising the steps of:
s1: conveying the raw water in the raw water tank and ozone to the mixer and the self-cleaning filter together to oxidize and decompose pollutants in the raw water;
s2: conveying the raw water subjected to oxidative decomposition to the ultrafiltration equipment for filtration, then conveying the raw water into the water production tank as product water, and simultaneously recovering and decomposing the ozone entering the water production tank through the tail gas destruction device and then discharging the ozone out of the system;
s3: and the product water of the water production tank is conveyed to a water production outlet at the top of the ultrafiltration equipment by using the backwashing water pump, membrane wires in the ultrafiltration equipment are backwashed reversely, and meanwhile, the membrane wires in the ultrafiltration equipment are subjected to air oscillation and air bubble scrubbing by the air compressor subsystem.
7. The method for cleaning the ultrafiltration membrane according to claim 6, wherein in the step S1, the adding concentration of the ozone is 6-40 mg/L.
8. The method for cleaning an ultrafiltration membrane according to claim 6, wherein the step S3 further comprises: and the medicament and/or the acid agent are sent to a water inlet at the bottom of the ultrafiltration equipment through the medicament feeding pump and/or the acid agent feeding pump of the medicament feeding and cleaning subsystem.
9. A method for cleaning an ultrafiltration membrane, the method using the system of any one of claims 1 to 5, comprising the steps of:
s1: conveying raw water in the raw water tank to the self-cleaning filter, and performing primary filtration treatment on the raw water;
s2: conveying the raw water subjected to the primary filtration treatment to the ultrafiltration equipment for secondary filtration treatment, and then conveying the raw water into the water production tank to be used as product water;
s3: conveying the product water in the water production tank and the ozone to the mixer and a top water production outlet of the ultrafiltration equipment by using the backwashing water pump, reversely carrying out oxidation backwashing on membrane wires in the ultrafiltration equipment, and simultaneously carrying out air oscillation and bubble scrubbing on the membrane wires in the ultrafiltration equipment by using the air compressor subsystem; and the ozone entering the water production tank is recycled and decomposed by the tail gas destruction device and then discharged out of the system.
10. The method for cleaning an ultrafiltration membrane according to claim 9,
in step S3, the adding concentration of the ozone is 6-40 mg/L;
the step S3 further includes: and the medicament and the acid agent are delivered to a water inlet at the bottom of the ultrafiltration equipment through the medicament feeding pump and the acid agent feeding pump of the medicament feeding and cleaning subsystem.
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Application publication date: 20220805 |