CN114797483A - Cleaning method and device for filtering membrane of water purification process - Google Patents
Cleaning method and device for filtering membrane of water purification process Download PDFInfo
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- CN114797483A CN114797483A CN202210579407.9A CN202210579407A CN114797483A CN 114797483 A CN114797483 A CN 114797483A CN 202210579407 A CN202210579407 A CN 202210579407A CN 114797483 A CN114797483 A CN 114797483A
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Abstract
A cleaning method of a water purification process filtering membrane comprises the following steps: setting the ozone concentration of the ozone generator to be 1-10mg/L and setting the compressed air volume of the compressor to be 10-20L/(m) 2 S), setting the air washing time to be 1-3min, and carrying out air washing; mixing water in the water production tank with an ozone generator and a compressor air source, and performing air-water combined washing on the membrane, wherein the combined washing time is set to be 5-10 min; pickling with a pickling tank, wherein the flow rate of the membrane surface is 0-5 m/s during cleaning, and the cleaning time is 10-100 min; and after the pickling is finished, cleaning by using a cleaning agent pool, and cleaning by soaking and/or cross flow, wherein the flow rate of the membrane surface is 0.1-5 m/s, the soaking cleaning time is 2-200h, and the cross flow cleaning time is 5-500 min. The invention also provides a device for realizing the method. The invention can completely and quickly recover the membrane flux loss by combining daily cleaning and deep cleaning, and accelerate the regeneration of a membrane system; the membrane cleaning frequency is reduced, and the stability of the membrane system is improved; the membrane is not damaged, and the consistency of the membrane performance before and after cleaning is ensured.
Description
Technical Field
The invention relates to the field of physics, in particular to a water treatment technology, and particularly relates to a method and a device for cleaning a filtering membrane in a water purification process.
Background
Membrane fouling refers to the phenomenon in which certain components in raw water are deposited on the membrane surface or in the membrane pores during membrane separation, resulting in a continuous decrease in the membrane filtration flux. In the application process, after the membrane is polluted to a certain degree, the membrane must be cleaned and regenerated to recover the filtration flux and the interception performance of the membrane.
The water purifying treatment process mainly takes surface water and underground water as water sources, and the surface water and the underground water enter a membrane system after being pretreated by flocculation, sedimentation and the like, and finally filtered water is supplied to users. At present, the conventional cleaning mode of the membrane system is gas/water backwashing, namely clean water and water are used as a backwashing gas source and a backwashing water source. Because a water source is gradually polluted by organic matters, heavy metals and the like, and the added medicament components are complex and the like, suspended solids, particles, organic matters, bacteria, biological pollutants and the like can be often intercepted on the surface of the membrane and the membrane holes, while the intercepted suspended solids and particles with large particle sizes can be effectively removed by a conventional cleaning mode, but fine particles, organic matters, bacteria, biological pollutants and the like which are difficult to be intercepted by the membrane holes can not be completely removed, the membrane flux can not be completely recovered, finally, the cost is gradually increased, the service life of the membrane is gradually reduced, and the wide popularization of the membrane process is influenced.
Disclosure of Invention
The invention aims to provide a method and a device for cleaning a filtering membrane in a water purification process, which aim to solve the technical problem that the filtering membrane cannot be thoroughly cleaned by the cleaning method in the prior art.
The invention discloses a cleaning method of a filtering membrane of a water purification process, which comprises the following steps:
the method comprises the following steps of firstly, cleaning a filtering membrane daily, stopping water production when the working operation time of the filtering membrane reaches a first set time or the membrane passing pressure difference exceeds 15-20%, then starting an ozone generator and an air compressor, setting the ozone concentration of the ozone generator to be 1-10mg/L, and setting the compressed air volume of the air compressor to be 10-20L/(m/L) 2 S), setting the air washing time to be 1-3min, adding ozone into compressed air to wash the filtering membrane, starting a water pump after the air washing is finished, mixing water in a water production tank with ozone in an ozone generator and compressed air in an air compressor by using a mixing device, and then carrying out air-water combined washing on the filtering membrane, wherein the combined washing time is set to be 5-10 min;
secondly, deeply cleaning the filtering membrane, stopping water production when the working operation time of the filtering membrane reaches a second set time and/or the daily cleaning frequency reaches a set frequency and/or the transmembrane pressure difference exceeds 30%, and performing acid cleaning on the filtering membrane by using an acid cleaning tank, wherein the flow rate of the surface of the filtering membrane is 0-5 m/s during cleaning, and the cleaning time is 10-100 min; and after the pickling is finished, cleaning the filtering membrane by using a cleaning agent in a cleaning agent pool, and cleaning by soaking and/or cross flow, wherein the flow speed of the membrane surface is 0.1-5 m/s during cleaning, the soaking cleaning time is 2-200h, and the cross flow cleaning time is 5-500 min.
Further, the first set time is 12-24 hours.
Further, the second set time is 4-8 weeks.
Further, the setting frequency is 30-60 times.
Further, the pickling tank uses any one or a mixture of two of organic acid or inorganic acid, the inorganic acid is at least one of hydrochloric acid, nitric acid or sulfuric acid, the mass percentage concentration of the organic acid or the inorganic acid is 1-20%, and the pH value is 2-3.
The cleaning agent further comprises a cleaning promoter, a chelating agent, a pH regulator and water, wherein the cleaning promoter is any one or a mixture of two of oxalic acid and citric acid, the concentration of the cleaning promoter in the cleaning agent is 1.1mmol/L, the chelating agent is any one or a mixture of two of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid, the concentration of the chelating agent in the cleaning agent is 0.001-1 mol/L, the pH regulator is one or a mixture of more than two of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate, and the pH value of the cleaning agent is 10-14 after the pH value regulator is added.
The cleaning device for the filtering membrane of the water purification process for realizing the method comprises an ozone generator, an air compressor, a water pump, a pickling tank, a cleaning agent tank, a water production tank, a mixer and a filtering device, wherein the filtering device is internally provided with the filtering membrane, the first end of the filtering device is connected with a raw water pipeline, the second end of the filtering device is connected with an inlet of the water production tank through a pipeline, a water supply end of the water production tank is connected with a water supply pipeline, the second end of the filtering device is also respectively connected with an outlet of the mixer, the pickling tank and the cleaning agent tank through pipelines, the first inlet of the mixer is respectively connected with the ozone generator and an outlet of the air compressor through pipelines, the second inlet of the mixer is connected with an outlet of the water pump through a pipeline, and an inlet of the water pump is connected with an outlet of the water production tank through a pipeline.
Compared with the prior art, the invention has positive and obvious effect. In the air washing process, the compressed air can generate stronger airflow and blow off fine suspended particles, impurities and the like intercepted on the surface and in the gaps of the membrane; the ozone has strong oxidizing property, can remove bacteria on the surface and in gaps of the film, can also remove substances such as color, taste, organic matters, phenols and the like, and also has good removing effect on inorganic matters such as cyanide, sulfide, nitrite and the like; in the combined washing process, various pollutants are carried by water and discharged out of the membrane, the membrane flux is finally recovered, the stability of the membrane system is improved, and the water quality and the water quantity of produced water are improved; the acid washing and cleaning agent can remove scales such as calcium carbonate, magnesium hydroxide, barium sulfate and the like deposited on the surface of the membrane and in gaps for a long time. The combination of daily cleaning and deep cleaning can completely and quickly recover the membrane flux loss and accelerate the regeneration of a membrane system; the membrane cleaning frequency is reduced, and the stability of the membrane system is improved; the membrane is not damaged, and the consistency of the membrane performance before and after cleaning is ensured.
Drawings
Fig. 1 is a schematic view of a cleaning device for a filtering membrane of a water purification process according to the present invention.
Detailed Description
The present invention will be further described with reference to the drawings and examples, but the present invention is not limited to the examples, and all similar structures and similar variations using the present invention shall fall within the scope of the present invention.
Example 1
As shown in fig. 1, the method for cleaning a filtration membrane of a water purification process (taking backwashing as an example) of the present invention comprises the following steps:
the first step, the filtering membrane 1 is cleaned daily, the daily cleaning comprises air washing and air-water combined washing, when the working operation time of the filtering membrane 1 reaches 12-24h or the membrane pressure difference exceeds 15-20%, the water production is stopped, then the ozone generator 2 and the air compressor 3 are started, the ozone concentration of the ozone generator 2 is set to be 1-10mg/L, the compressed air quantity of the air compressor 3 is set to be 10-20L/(m) 2 S), setting the air washing time to be 1-3min, and adding ozone into compressed air to wash the filter membrane 1; after the air washing is finished, the water pump 4 is started, water in a water production tank 7 is mixed with ozone in the ozone generator 2 and compressed air in the air compressor 3 by a mixing device 8, the air-water combined washing is carried out on the filtering membrane 1, and the combined washing time is set to be 5-10 min;
in the air washing process, the compressed air can generate stronger airflow and can blow off fine suspended particles, impurities and the like intercepted on the surface and the gaps of the filtering membrane 1; the ozone has strong oxidizing property, can remove bacteria on the surface and in gaps of the filtering membrane 1, can also remove substances such as color, taste, organic matters, phenols and the like, and also has good removing effect on inorganic matters such as cyanide, sulfide, nitrite and the like; in the combined washing process, various pollutants are carried by water and discharged out of the filtering membrane 1, the membrane flux is finally recovered, the stability of the membrane system is improved, and the water quality and the water quantity of produced water are improved;
a second step, carrying out deep cleaning on the filtering membrane 1, stopping water production when the working operation time of the filtering membrane 1 reaches a second set time of 4-8 weeks and/or the daily cleaning frequency reaches a set frequency of 30-60 times and/or the transmembrane pressure difference exceeds 30%, carrying out acid cleaning on the filtering membrane 1 by using an acid cleaning tank 5, wherein the acid cleaning tank uses organic acid and/or inorganic strong acid which is at least one of hydrochloric acid, nitric acid or sulfuric acid, the mass percentage concentration is 1-20%, the pH value is 2-3, the surface flow rate of the filtering membrane 1 is 0-5 m/s during cleaning, and the cleaning time is 10-100 min; after the acid cleaning is finished, cleaning the filtering membrane 1 by using a cleaning agent in a cleaning agent pool 6, wherein the cleaning agent comprises a cleaning promoter, a chelating agent, a pH regulator and water, the cleaning promoter is any one or a mixture of two of oxalic acid and citric acid, the concentration of the cleaning promoter in the cleaning agent is 1.1mmol/L, the chelating agent is any one or a mixture of two of diethylenetriaminepentaacetic acid and ethylenediamine tetraacetic acid, the concentration of the chelating agent in the cleaning agent is 0.001-1 mol/L, the pH regulator is any one or a mixture of more than two of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate, the pH value of the cleaning agent is 10-14 after the pH value regulator is added, the cleaning is carried out by a soaking type and/or a cross flow type, the flow rate of the surface of the filtering membrane 1 is 0.1-5 m/s during the cleaning, and the soaking type cleaning time is 2-200h, the cross-flow cleaning time is 5-500 min.
The acid washing and the cleaning agent can remove scales such as calcium carbonate, magnesium hydroxide, barium sulfate and the like deposited on the surface of the filtering membrane 1 and in the gap for a long time. The combination of daily cleaning and deep cleaning can completely and quickly recover the membrane flux loss and accelerate the regeneration of the filtering membrane 1 system; the membrane cleaning frequency is reduced, and the system stability of the filtering membrane 1 is improved; no damage to the membrane is caused, and the consistency of the performance of the filtering membrane 1 before and after cleaning is ensured.
The specific cleaning mode can be forward washing or back washing, and is determined according to the properties of the membrane.
A cleaning device for realizing the cleaning method comprises an ozone generator 2, an air compressor 3, a water pump 4, a pickling tank 5, a cleaning agent tank 6, a water production tank 7, a mixer 8 and a filtering device, wherein a filtering membrane 1 is arranged in the filtering device, the first end of the filtering device is connected with a raw water pipeline 9, the second end of the filtering device is connected with an inlet of the water production tank 7 through a pipeline, a water supply end of the water production tank 7 is connected with a water supply pipeline 10, the second end of the filtering device is also connected with outlets of the mixer 8, the pickling tank 5 and the cleaning agent tank 6 through pipelines respectively, a first inlet of the mixer 8 is connected with outlets of the ozone generator 2 and the air compressor 3 through pipelines respectively, a second inlet of the mixer 8 is connected with an outlet of the water pump 4 through a pipeline, and an inlet of the water pump 4 is connected with an outlet of the water production tank 7 through a pipeline.
Specifically, the ozone generator 2, the air compressor 3, the water pump 4, the pickling tank 5, the cleaning agent tank 6, the water production tank 7, the mixer 8, the filtering device, and the like in this embodiment all adopt known solutions in the prior art, and those skilled in the art are aware of these solutions and will not be described herein again.
Claims (7)
1. A cleaning method of a water purification process filtering membrane is characterized by comprising the following steps:
the first step, daily cleaning is carried out on the filtering membrane, and when the working operation time of the filtering membrane reaches a first set time or the pressure difference of the filtering membrane exceeds 15-20%, the operation is stoppedProducing water, starting an ozone generator and an air compressor, setting the ozone concentration of the ozone generator to be 1-10mg/L and setting the air volume of compressed air of the air compressor to be 10-20L/(m) 2 S), setting the air washing time to be 1-3min, adding ozone into compressed air to wash the filtering membrane, starting a water pump after the air washing is finished, mixing water in a water production tank with ozone in an ozone generator and compressed air in an air compressor by using a mixing device, and then carrying out air-water combined washing on the filtering membrane, wherein the combined washing time is set to be 5-10 min;
secondly, deeply cleaning the filtering membrane, stopping water production when the working operation time of the filtering membrane reaches a second set time and/or the daily cleaning frequency reaches a set frequency and/or the transmembrane pressure difference exceeds 30%, and performing acid cleaning on the filtering membrane by using an acid cleaning tank, wherein the flow rate of the surface of the filtering membrane is 0-5 m/s during cleaning, and the cleaning time is 10-100 min; and after the pickling is finished, cleaning the filtering membrane by using a cleaning agent in a cleaning agent pool, and cleaning by soaking and/or cross flow, wherein the flow speed of the membrane surface is 0.1-5 m/s during cleaning, the soaking cleaning time is 2-200h, and the cross flow cleaning time is 5-500 min.
2. The method for cleaning the filtering membrane of the water purification process according to claim 1, wherein the first set time is 12-24 hours.
3. The method for cleaning the filtering membrane of the water purification process according to claim 1, wherein the second set time is 4-8 weeks.
4. The method for cleaning the filtering membrane of the water purification process according to claim 1, wherein the set frequency is 30-60 times.
5. The method for cleaning the filtering membrane of the water purification process according to claim 1, wherein the acid washing tank uses one or a mixture of two of organic acid and inorganic acid, the inorganic acid is at least one of hydrochloric acid, nitric acid or sulfuric acid, the mass percentage concentration of the organic acid or the inorganic acid is 1-20%, and the pH value is 2-3.
6. The method for cleaning the filtering membrane in the water purification process according to claim 1, wherein the cleaning agent comprises a cleaning promoter, a chelating agent, a pH regulator and water, wherein the cleaning promoter is any one or a mixture of two of oxalic acid and citric acid, the concentration of the cleaning promoter in the cleaning agent is 1.1mmol/L, the chelating agent is any one or a mixture of two of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid, the concentration of the chelating agent in the cleaning agent is 0.001-1 mol/L, the pH regulator is one or a mixture of more than two of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate, and the pH value of the cleaning agent is 10-14 after the pH regulator is added.
7. The cleaning device for the filtering membrane of the water purification process for realizing the cleaning method of claim 1 is characterized by comprising an ozone generator, an air compressor, a water pump, a pickling tank, a cleaning agent tank, a water production tank, a mixer and a filtering device, wherein the filtering device is internally provided with the filtering membrane, the first end of the filtering device is connected with a raw water pipeline, the second end of the filtering device is connected with an inlet of the water production tank through a pipeline, a water supply end of the water production tank is connected with a water supply pipeline, the second end of the filtering device is also respectively connected with outlets of the mixer, the pickling tank and the cleaning agent tank through pipelines, the first inlet of the mixer is respectively connected with outlets of the ozone generator and the air compressor through pipelines, the second inlet of the mixer is connected with an outlet of the water pump through a pipeline, and an inlet of the water pump is connected with an outlet of the water production tank through a pipeline.
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| CN202210579407.9A CN114797483A (en) | 2022-05-26 | 2022-05-26 | Cleaning method and device for filtering membrane of water purification process |
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| CN202210579407.9A CN114797483A (en) | 2022-05-26 | 2022-05-26 | Cleaning method and device for filtering membrane of water purification process |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117443197A (en) * | 2023-12-22 | 2024-01-26 | 天津工业大学 | Method for offline cleaning MBR hollow fiber membrane by utilizing ozone micro-nano bubbles |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117443197A (en) * | 2023-12-22 | 2024-01-26 | 天津工业大学 | Method for offline cleaning MBR hollow fiber membrane by utilizing ozone micro-nano bubbles |
| CN117443197B (en) * | 2023-12-22 | 2024-03-29 | 天津工业大学 | Method for offline cleaning MBR hollow fiber membrane by utilizing ozone micro-nano bubbles |
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