CN101402021B - Pressurizing dissolved air flotation cleaning method for organic pollutant on reverse osmosis membrane - Google Patents
Pressurizing dissolved air flotation cleaning method for organic pollutant on reverse osmosis membrane Download PDFInfo
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Abstract
The invention relates to a pressurized dissolved air flotation cleaning method for organic pollutant on a reverse osmosis membrane, which belongs to the technical field of membrane separation in the chemical engineering science. The pressurized dissolved air flotation cleaning method adopts a high-pressure pump to send a cleaning liquid into a pressurized dissolved air flotation device from a raw water tank; the cleaning liquid is mixed with air which is then dissolved in the cleaning liquid; after the pressure is reached, an outlet valve is opened and the air is released into microbubbles in the state of dissolution; the bubbles are fully mixed with the cleaning liquid, and mixed gas-liquid mixture is sent into the raw water tank for circulation; generated gas-liquid mixed cleaning liquid is inputted into a reverse osmosis membrane machine from the other high-pressure pump, so as to clean the organic pollutant on the membrane; and the cleaning liquid is circulated into the raw water tank. The pressurized dissolved air flotation cleaning method achieves the cleaning efficiency by recording of the time variation of parameters of the cleaning liquid and the variation of the permeation flux of standard water before and after the reverse osmosis membrane is polluted. The pressurized dissolved air flotation cleaning method obviously improves the cleaning efficiency of the organic pollutant of the reverse osmosis membrane, prolongs the service life of the membrane, and reduces the cost of a medicine for cleaning the membrane.
Description
Technical field
The present invention relates to a kind of pressurizing dissolved air flotation cleaning method of organic pollutant on reverse osmosis membrane, be specifically related to a kind of gas-liquid mixture that includes countless microbubbles that utilizes the pressurized dissolved air flotation device to produce is strengthened cleaning to the organic pollution on the reverse osmosis membrane method.Belong to membrane separation technique field in the chemical engineering science.
Background technology
Counter-infiltration since have easy to operate, system's floor space is little, energy consumption is low, the outstanding advantage of product water stabilization and operating cost economic dispatch, has been widely used in the preparation of electronics industry ultra-pure water, wastewater treatment and fields such as drinking-water, beverage and Chemical Manufacture.Along with the improvement of masking technique and reverse osmosis process constantly increase in economical, technical competitiveness, will become one of leading new and high technology of 21 century desalination and other water treatment field.
Yet in the actual application of reverse osmosis membrane separation technology, membrane pollution problem is one of bottleneck of further developing of reverse osmosis technology.Film pollutes not only to make and produces water water quality deterioration, producing water ratio decline, system pressure drop increase, energy consumption increases, and is used for the drug expenditure increase that film cleans, and can causes irreversible damage to film, shorten the life-span of film, influenced the economy of reverse osmosis technology to a certain extent.
Reverse osmosis membrane pollutes and mainly is divided into inorganic pollution, colloid pollution, organic matter pollution and biological pollution.Because the organic matter that is dissolved in the water body has electric charge mostly, can be adsorbed on the film surface securely and form the organic matter thin layer, therefore to pollute be that to allow the counter-infiltration industry have a headache most at present also be the problem that is difficult to solve most to organic matter, it not only can cause reverse osmosis membrane performance to fail fast, the salt rejection rate, producing water ratio that makes reverse osmosis membrane fast, significantly reduce, and the film after being polluted by organic matter is difficult to clean up, and is reversible hardly.Therefore the organic matter of film pollutes to clean and more and more causes people's attention.Being used for reverse osmosis membrane organic matter pollution cleaning way at present mainly is chemical cleaning method, comprises NaOH cleaning, EDTA (disodium ethylene diamine tetraacetate) cleaning etc.But these methods generally clean concentration higher, cleaning performance preferably just arranged when the pH value is higher, it is higher to clean drug expenditure on the one hand, cause reverse osmosis membrane operating cost to increase, Chemical cleaning can cause to a certain degree damage to reverse osmosis membrane for a long time on the other hand.Therefore, research and develop new suitable reverse osmosis membrane organic matter and pollute the method for cleaning, have great significance for the normal operation that prolongs membrane lifetime and reverse osmosis unit.
Summary of the invention
The objective of the invention is at the deficiencies in the prior art, a kind of pressurizing dissolved air flotation cleaning method of organic pollutant on reverse osmosis membrane is provided, can significantly improve the permeation flux regeneration rate of reverse osmosis membrane and the cleaning efficiency of film, prolong the life-span of film, reduce counter-infiltration system operating cost.
For realizing such purpose, in the technical scheme of the present invention, adopt high-pressure pump that the cleaning fluid for preparing is sent into the pressurized dissolved air flotation device from former tank, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, and make air dissolves in cleaning fluid, reach the outlet valve on the device for opening behind the certain pressure, make air under dissolved state, be released into microbubble, and by the outlet shower nozzle bubble is fully mixed with cleaning fluid, mixed gas-liquid mixture is sent back in the former tank to circulate.Then, the gas-liquid mixed cleaning fluid that said process generates is input to the cleaning of carrying out organic pollution on the film in the reverse osmosis membrane device by another high-pressure pump, the Hydrodynamic turbulence power and the bubble adhesive force that utilize in the cleaning fluid existence because of microbubble to increase, reach the purpose that strengthens cleaning efficiency, cleaning fluid loops back former tank then.The parameters such as permeation flux regeneration rate of temperature, reverse osmosis membrane by the record cleaning fluid over time, and reverse osmosis membrane pollute before and after the permeation flux of standard water change, obtain cleaning efficiency.
The concrete implementation step of the inventive method is as follows:
The first step, employing standard water (activated carbon filtration running water, deionized water etc.) test reverse osmosis membrane initial aquifer yield Jv0 value before organic contamination takes place keep temperature constant (15-35 ℃), constant pressure (0.8-4Mpa) during test.
Second step, preparation organic pollution solution, regulate the cooling water flow in concentrate control valve, bypass valve and the heat exchanger in the counter-infiltration system pipeline, making this system is that 15-35 ℃, pressure are operation 1-20 hour under the condition of 0.8-4Mpa in temperature, makes the organic pollution that generates on the reverse osmosis membrane cause product to fall 15-85% under water.
The 3rd step, according to the organic pollution that generates on the film, by membrane technology handbook (as LG-DOW reverse osmosis membrane technology handbook etc.) configuration corresponding cleaning solution.By first high-pressure pump this cleaning fluid is sent in the pressurized dissolved air flotation device, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, when treating that pressure in the pressurized dissolved air flotation device is 0.2-0.6MPa, open the valve of air and liquid mixer, send gas-liquid mixture back to former tank by shower nozzle.
The 4th step, startup counter-infiltration system clean the gas-liquid mixture that said process generates by second high-pressure pump in former tank input reverse osmosis membrane device.Temperature constant (15-35 ℃) when keeping cleaning, cleaning pressure P1 constant (0-0.4MPa).Heightened the second high-pressure pump pressure to setting value P2 (0.8-4Mpa) every 2 minutes in the cleaning process, read in the infiltration aquifer yield of reverse osmosis membrane under the P2 pressure after, again the second high-pressure pump pressure is recalled to former cleaning pressure P1 and proceeds to clean.Like this repeatable operation, the infiltration aquifer yield that obtains reverse osmosis membrane under the P2 pressure obtains the permeation flux regeneration rate over time.
After the 5th step, reverse osmosis membrane clean half an hour, adopt the aquifer yield Jv of condition test reverse osmosis membrane after cleaning in the first step.Calculate Jv/Jv0 thus, obtain the cleaning efficiency of gas-liquid mixture.
The above-mentioned counter-infiltration system of the present invention, pipeline, air and liquid mixer, reverse osmosis membrane device, high-pressure pump etc. all are common components of the prior art.
The type of organic pollution of the present invention is humic acid, alginates, protein, aliphatic acid, dissolved organic matter, dissolubility microbial product etc., can be one or more mixtures in these organic pollutions.Reverse osmosis membrane can adopt 8 inches of present commercial diameters, 4 inches, 2.5 inches membrane component, hollow fibre membrane component and flat membrane component.
The pressurizing dissolved air flotation cleaning method that the inventive method adopts, the bubble that produces is owing to be to disengage under dissolved state, can reach very thin, can be with the size Control of bubble at the 10-40 micron, therefore the gas-liquid mixture that produces is very even, no gas phase skewness problem, the less turbulence and the bubble adhesive force of cleaning fluid fluid have been increased thus, can significantly improve the cleaning efficiency and the permeation flux regeneration rate of organic pollutant on reverse osmosis membrane, for alleviating the reverse osmosis membrane organic contamination, prolong membrane lifetime, reduce film cleaning cost of drugs a kind of simple and easy to do method is provided.
Description of drawings
Fig. 1 is experimental provision structure of the present invention and experiment flow figure.
Fig. 2 is the result of the embodiment of the invention 1 and embodiment 2.
Fig. 3 is the result of the embodiment of the invention 3.
Fig. 4 is the result of the embodiment of the invention 4.
The specific embodiment
Below in conjunction with drawings and Examples, polluting with the organic pollution humic acid that extensively exists is that example is further described technical scheme of the present invention.Following examples do not constitute limitation of the invention.
Fig. 1 is experimental provision structure and the experiment flow figure that the inventive method adopted.As shown in Figure 1, whole system is divided into 2 sub-circulatory systems again: one is reverse osmosis membrane system, is used for film pollution and film and cleans; Another is the gas-liquid mixed system, produces the gas-liquid mixed cleaning fluid by the pressurized dissolved air flotation device.Two shared former tanks of system.In reverse osmosis membrane system, adopt low pressure flat plate reverse osmosis film, membrane area is 1.39 * 10
-2m
2, reverse osmosis membrane concentrate port is installed control valve, flow is taken into account heat exchanger, and the concentrate that comes out from reverse osmosis membrane all is back to former tank and circulates.In the reverse osmosis membrane permeate port range of flow meter in a small amount is installed, and is made whole penetrating fluids be back to former tank to circulate.Second high-pressure pump-membrane pump is installed between former tank and the reverse osmosis membrane, bypass and bypass valve are installed behind membrane pump, be used to regulate the inlet flow rate and the pressure of reverse osmosis membrane.In the gas-liquid mixed system, first high-pressure pump is installed between former tank and the pressurized dissolved air flotation device, mounting heat exchanger behind first high-pressure pump is used to keep cleaning process Central Plains tank rinse liquid temperature constant.
Embodiment 1
Whole system is divided into 2 sub-circulatory systems, and as shown in Figure 1: one is reverse osmosis membrane system, is used for film pollution and film and cleans; Another is the gas-liquid mixed system, produces the gas-liquid mixed cleaning fluid by the pressurized dissolved air flotation device.Two shared former tanks of system.
In reverse osmosis membrane system, adopt low pressure flat plate reverse osmosis film, flat sheet membrane is taken from the TW30-1812 film that Beijing peace moral film separates company, and membrane area is 1.39 * 10
-2m
2The reverse osmosis concentrated liquid port is installed control valve, flow is taken into account heat exchanger, and the concentrate that comes out from reverse osmosis membrane all is back to former tank and circulates.In the reverse osmosis membrane permeate port range of flow meter in a small amount is installed, and is made whole penetrating fluids be back to former tank to circulate.Second high-pressure pump-membrane pump is installed between former tank and the reverse osmosis membrane, bypass and bypass valve are installed behind membrane pump, be used to regulate the inlet flow rate and the pressure of reverse osmosis membrane.
In the gas-liquid mixed system, first high-pressure pump is installed between former tank and the pressurized dissolved air flotation device, mounting heat exchanger behind first high-pressure pump is used to keep cleaning process Central Plains tank rinse liquid temperature constant.
Adopt activated carbon filtration running water test reverse osmosis membrane initial aquifer yield Jv0 value before organic contamination takes place, keeping temperature constant during test is 20 ℃, and constant pressure is 1Mpa.
Take by weighing 0.8g humic acid powder, be dissolved in the ultra-pure water, and add concentrated hydrochloric acid solution adjusting pH=1, stirred one hour, make it abundant mixing, and then use NaOH solution, regulate pH=13, stirred one hour, after leaving standstill two hours, filter twice with quantitative filter paper, undissolved humic acid sediment filters out, the humic acid solution for preparing is poured in the former tank, and added 8.88g CaCl
2With 32.8gNaCl in former tank, regulating pH with concentrated hydrochloric acid is 4, is mixed with the 10L foul solution, carries out the humic acid pollution course of reverse osmosis membrane.Regulate the cooling water flow in concentrate control valve, bypass valve and the heat exchanger in the reverse osmosis membrane system pipeline, making system is that 30 ℃, pressure are that 0.8Mpa, concentrated solution discharge are operation 1-2 hour under the condition of 60L/h in temperature, and makes the organic pollution that generates on the reverse osmosis membrane cause aquifer yield to descend 50%.
Foul solution in the system of then draining adds the running water of 30L behind activated carbon filtration and cleans as cleaning fluid in former tank.Adopt two kinds of methods to carry out during cleaning, the one, directly adopt this cleaning fluid to carry out, the 2nd, this cleaning fluid after handling, the pressurized dissolved air flotation device is carried out.When handling with the pressurized dissolved air flotation device, start the gas-liquid mixed system, by first high-pressure pump this cleaning fluid is sent in the pressurized dissolved air flotation device, the first high-pressure pump flow is 650L/h, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, when treating that pressure in the pressurized dissolved air flotation device is 0.2MPa, open the valve of air and liquid mixer, sending gas-liquid mixture back to former tank by shower nozzle circulates, open heat exchanger in the processing procedure, be used for keeping former tank constant through the rinse liquid temperature of circulation.
When cleaning, start reverse osmosis membrane system, will clean in the above-mentioned cleaning fluid input reverse osmosis membrane device by second high-pressure pump, the cleaning flow is 60L/h, and cleaning temperature is 25 ℃, and cleaning fluid loops back former tank.Open the bypass valve in the reverse osmosis membrane system during cleaning, plus-pressure does not carry out, and opens heat exchanger, keeps rinse liquid temperature constant.Heightened the second high-pressure pump pressure to 1Mpa every 2 minutes in the cleaning process, read in the infiltration aquifer yield of reverse osmosis membrane under the 1Mpa pressure after, again the second high-pressure pump pressure is recalled to former cleaning pressure and proceeds to clean.Like this repeatable operation, the infiltration aquifer yield that obtains reverse osmosis membrane under the 1Mpa pressure obtains the permeation flux regeneration rate over time.
After reverse osmosis membrane cleans half an hour, adopt with reverse osmosis membrane and pollute the preceding identical aquifer yield Jv of condition test film after cleaning.Calculate Jv/Jv0 thus, obtain cleaning efficiency.
Result of implementation as shown in Figure 2.As can be seen from Figure 2, running water is handled the simple running water height of cleaning efficiency of the gas-liquid mixture that the back produces through the pressurized dissolved air flotation device, and the cleaning efficiency of gas-liquid mixture is 51.3%, and the efficient during simple running water cleaning only is 31.6%.
The present embodiment explanation, cleaning for the organic pollutant on reverse osmosis membrane humic acid, when adopting running water directly non-chemically to clean, the gas-liquid mixture that pressurized dissolved air flotation produces has invigoration effect to the cleaning of reverse osmosis membrane, can increase cleaning efficiency, improve reverse osmosis membrane permeation flux regeneration rate.
Embodiment 2
It is that EDTA tests that present embodiment changes the cleaning fluid kind.System disposition as shown in Figure 1.
Adopt activated carbon filtration running water test reverse osmosis membrane initial aquifer yield Jv0 value before organic contamination takes place, keeping temperature constant during test is 20 ℃, and constant pressure is 1Mpa.
Take by weighing 0.8g humic acid powder, be dissolved in the ultra-pure water, and add concentrated hydrochloric acid solution adjusting pH=1, stirred one hour, make it abundant mixing, and then use NaOH solution, regulate pH=13, stirred one hour, after leaving standstill two hours, filter twice with quantitative filter paper, undissolved humic acid sediment filters out, the humic acid solution for preparing is poured in the former tank, and added 8.88g CaCl
2With 32.8gNaCl in former tank, regulating pH with concentrated hydrochloric acid is 4, is mixed with the 10L foul solution, carries out the humic acid pollution course of reverse osmosis membrane.Regulate the cooling water flow in concentrate control valve, bypass valve and the heat exchanger in the reverse osmosis membrane system pipeline, making system is that 30 ℃, pressure are that 0.8Mpa, concentrated solution discharge are operation 1-2 hour under the condition of 60L/h in temperature, and makes the organic pollution that generates on the reverse osmosis membrane cause aquifer yield to descend 50%.
Foul solution in the system of then draining adds the running water of 30L behind activated carbon filtration in former tank, the preparation cleaning fluid.Cleaning fluid adopts 0.1mM EDTA solution.Adopt two kinds of methods to carry out during cleaning, the one, directly adopt this cleaning fluid to carry out, the 2nd, this cleaning fluid after handling, the pressurized dissolved air flotation device is carried out.When handling with the pressurized dissolved air flotation device, start the gas-liquid mixed system, by first high-pressure pump this cleaning fluid is sent in the pressurized dissolved air flotation device, the first high-pressure pump flow is 650L/h, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, when treating that pressure in the pressurized dissolved air flotation device is 0.2MPa, open the valve of air and liquid mixer, sending gas-liquid mixture back to former tank by shower nozzle circulates, open heat exchanger in the processing procedure, be used for keeping former tank constant through the rinse liquid temperature of circulation.
When cleaning, start reverse osmosis membrane system, will clean in the above-mentioned cleaning fluid input film device by second high-pressure pump, the cleaning flow is 60L/h, and cleaning temperature is 25 ℃, and cleaning fluid loops back former tank.Open the bypass valve in the reverse osmosis membrane system during cleaning, plus-pressure does not carry out, and opens heat exchanger, keeps rinse liquid temperature constant.Heightened the second high-pressure pump pressure to 1Mpa every 2 minutes in the cleaning process, read in the infiltration aquifer yield of reverse osmosis membrane under the 1Mpa pressure after, again the second high-pressure pump pressure is recalled to former cleaning pressure and proceeds to clean.Like this repeatable operation, the infiltration aquifer yield that obtains reverse osmosis membrane under the 1Mpa pressure obtains the permeation flux regeneration rate over time.
After reverse osmosis membrane cleans half an hour, adopt with film and pollute the preceding identical aquifer yield Jv of condition test reverse osmosis membrane after cleaning.Calculate Jv/Jv0 thus, obtain cleaning efficiency.
Result of implementation as shown in Figure 2.As can be seen from Figure 2,0.1mM the more simple 0.1mM EDTA cleaning fluid height of cleaning efficiency of the gas-liquid mixture that the EDTA cleaning fluid produces after the pressurized dissolved air flotation device is handled, 0.1mM/L the cleaning efficiency of EDTA gas-liquid mixture is 70.1%, and the efficient of simple 0.1mM EDTA when cleaning only is 54.4%, and is almost suitable with the cleaning efficiency 51.3% of running water gas-liquid mixture.
The present embodiment explanation, for the cleaning of organic pollutant on reverse osmosis membrane humic acid, when adopting chemical agent to carry out Chemical cleaning, the gas-liquid mixture that pressurized dissolved air flotation produces has invigoration effect to the cleaning of reverse osmosis membrane, cleaning efficiency can be strengthened, the expense of cleaning medicine can be saved.
Embodiment 3
Present embodiment test cleaning fluid pH value is to the influence of cleaning efficiency.System disposition as shown in Figure 1.
Adopt activated carbon filtration running water test reverse osmosis membrane initial aquifer yield Jv0 value before organic contamination takes place, keeping temperature constant during test is 20 ℃, and constant pressure is 1Mpa.
Take by weighing 0.4g humic acid powder, be dissolved in the ultra-pure water, and add concentrated hydrochloric acid solution adjusting pH=1, stirred one hour, make it abundant mixing, and then use NaOH solution, regulate pH=13, stirred one hour, after leaving standstill two hours, filter twice with quantitative filter paper, undissolved humic acid sediment filters out, the humic acid solution for preparing is poured in the former tank, and added 4.44g CaCl
2With 16.4g NaCl in former tank, regulating pH with concentrated hydrochloric acid is 4, is mixed with the 10L foul solution, carries out the humic acid pollution course of reverse osmosis membrane.Regulate the cooling water flow in concentrate control valve, bypass valve and the heat exchanger in the reverse osmosis membrane system pipeline, making system is that 30 ℃, pressure are that 0.8Mpa, concentrated solution discharge are operation 1-2 hour under the condition of 60L/h in temperature, and makes the organic pollution that generates on the film cause aquifer yield to descend 30%.
Foul solution in the system of then draining adds the running water of 30L behind activated carbon filtration in former tank, the EDTA cleaning fluid of preparation 0.5mM, and its pH is respectively 4,6 and 11, cleans after the pressurized dissolved air flotation device is handled.When handling with the pressurized dissolved air flotation device, start the gas-liquid mixed system, by first high-pressure pump this cleaning fluid is sent in the pressurized dissolved air flotation device, the first high-pressure pump flow is 650L/h, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, when treating that pressure in the pressurized dissolved air flotation device is 0.2MPa, open the valve of air and liquid mixer, sending gas-liquid mixture back to former tank by shower nozzle circulates, open heat exchanger in the processing procedure, be used for keeping former tank constant through the rinse liquid temperature of circulation.
When cleaning, start reverse osmosis membrane system, will clean in the above-mentioned cleaning fluid input film device by second high-pressure pump, the cleaning flow is 60L/h, and cleaning temperature is 25 ℃, and cleaning fluid loops back former tank.Open the bypass valve in the reverse osmosis membrane system during cleaning, plus-pressure does not carry out, and opens heat exchanger, keeps rinse liquid temperature constant.Heightened the second high-pressure pump pressure to 1Mpa every 2 minutes in the cleaning process, read in the infiltration aquifer yield of reverse osmosis membrane under the 1Mpa pressure after, again the second high-pressure pump pressure is recalled to former cleaning pressure and proceeds to clean.Like this repeatable operation, the infiltration aquifer yield that obtains reverse osmosis membrane under the 1Mpa pressure obtains the permeation flux regeneration rate over time.
After reverse osmosis membrane cleans half an hour, adopt with reverse osmosis membrane and pollute the preceding identical aquifer yield Jv of condition test reverse osmosis membrane after cleaning.Calculate Jv/Jv0 thus, obtain cleaning efficiency.
Result of implementation as shown in Figure 3.As can be seen from Figure 3, rising along with cleaning fluid pH, cleaning efficiency also increases, cleaning efficiency is 58.7% during pH=4, and the cleaning efficiency of gas-liquid mixture is 130.9% during pH=11, explanation not only can recover the permeation flux of reverse osmosis membrane fully when so the EDTA cleaning fluid gas-liquid mixture of low concentration cleans, and makes the reverse osmosis membrane surface hydrophilicity stronger and increased the permeation flux of film to a certain extent.
Present embodiment shows that when adopting EDTA solution pressurized dissolved air flotation method to clean organic contamination, the pH value of rising cleaning fluid can improve cleaning efficiency.
Present embodiment test cleaning fluid flow velocity is to the influence of cleaning efficiency.System disposition as shown in Figure 1.
Adopt activated carbon filtration running water test reverse osmosis membrane initial aquifer yield Jv0 value before organic contamination takes place, keeping temperature constant during test is 20 ℃, and constant pressure is 1Mpa.
Take by weighing 0.4g humic acid powder, be dissolved in the ultra-pure water, and add concentrated hydrochloric acid solution adjusting pH=1, stirred one hour, make it abundant mixing, and then use NaOH solution, regulate pH=13, stirred one hour, after leaving standstill two hours, filter twice with quantitative filter paper, undissolved humic acid sediment filters out, the humic acid solution for preparing is poured in the former tank, and added 4.44g CaCl
2With 16.4g NaCl in former tank, regulating pH with concentrated hydrochloric acid is 4, is mixed with the 10L foul solution, carries out the humic acid pollution course of reverse osmosis membrane.Regulate the cooling water flow in concentrate control valve, bypass valve and the heat exchanger in the reverse osmosis membrane system pipeline, making system is that 30 ℃, pressure are that 0.8Mpa, concentrated solution discharge are operation 1-2 hour under the condition of 60L/h in temperature, and makes the organic pollution that generates on the reverse osmosis membrane cause aquifer yield to descend 30%.
Foul solution in the system of then draining adds the running water of 30L behind activated carbon filtration in former tank, the EDTA cleaning fluid of preparation 0.5mM cleans after the pressurized dissolved air flotation device is handled.When handling with the pressurized dissolved air flotation device, start the gas-liquid mixed system, by first high-pressure pump this cleaning fluid is sent in the pressurized dissolved air flotation device, the first high-pressure pump flow is 650L/h, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, when treating that pressure in the pressurized dissolved air flotation device is 0.2MPa, open the valve of air and liquid mixer, sending gas-liquid mixture back to former tank by shower nozzle circulates, open heat exchanger in the processing procedure, be used for keeping former tank constant through the rinse liquid temperature of circulation.
When cleaning, start reverse osmosis membrane system, will clean in the above-mentioned cleaning fluid input film device by second high-pressure pump, the cleaning fluid flow velocity is respectively 40L/h, and 60L/h and 80L/h, cleaning temperature are 25 ℃, and cleaning fluid loops back former tank.Open the bypass valve in the reverse osmosis membrane system during cleaning, plus-pressure does not carry out, and opens heat exchanger, keeps rinse liquid temperature constant.Heightened the second high-pressure pump pressure to 1Mpa every 2 minutes in the cleaning process, read in the infiltration aquifer yield of reverse osmosis membrane under the 1Mpa pressure after, again the second high-pressure pump pressure is recalled to former cleaning pressure and proceeds to clean.Like this repeatable operation, the infiltration aquifer yield that obtains reverse osmosis membrane under the 1Mpa pressure obtains the permeation flux regeneration rate over time.
After reverse osmosis membrane cleans half an hour, adopt with reverse osmosis membrane and pollute the preceding identical aquifer yield Jv of condition test reverse osmosis membrane after cleaning.Calculate Jv/Jv0 thus, obtain cleaning efficiency.
Result of implementation as shown in Figure 4.As can be seen from Figure 4, along with the rising of cleaning flow velocity, cleaning efficiency also increases, and cleaning efficiency is 52.2% when cleaning flow velocity 40L/h, and cleaning efficiency is 71.0% when cleaning flow velocity 80L/h, illustrate to increase the cleaning performance that the cleaning flow velocity can enlarge markedly gas-liquid mixture.
Present embodiment shows, when adopting EDTA solution pressurized dissolved air flotation method to clean organic contamination, increases and cleans flow velocity, can improve cleaning efficiency.
Claims (3)
1. the pressurizing dissolved air flotation cleaning method of an organic pollutant on reverse osmosis membrane is characterized in that comprising following concrete steps:
1) adopt standard water test reverse osmosis membrane initial aquifer yield Jv0 value before organic contamination takes place, keep temperature constant at 15-35 ℃ during test, constant pressure is at 0.8-4Mpa;
2) preparation organic pollution solution, regulate the cooling water flow in concentrate control valve, bypass valve and the heat exchanger in the reverse osmosis membrane system pipeline, making this system is that 15-35 ℃, pressure are operation 1-20 hour under the condition of 0.8-4Mpa in temperature, makes the organic pollution that generates on the reverse osmosis membrane cause product to fall 15-85% under water;
3) according to the organic pollution that generates on the film, configuration corresponding cleaning liquid in former tank, first high-pressure pump is installed between former tank and the pressurized dissolved air flotation device, and mounting heat exchanger behind first high-pressure pump is used for keeping cleaning process Central Plains tank rinse liquid temperature constant; By first high-pressure pump cleaning fluid in the former tank is sent in the pressurized dissolved air flotation device, cleaning fluid fully mixes with air in the pressurized dissolved air flotation device, when treating that pressure in the pressurized dissolved air flotation device is 0.2-0.6MPa, open the valve of air and liquid mixer, send gas-liquid mixture back to former tank by shower nozzle;
4) start counter-infiltration system, by second high-pressure pump gas-liquid mixture that said process generates is cleaned in former tank input reverse osmosis membrane device, temperature constant is at 15-35 ℃ when keeping cleaning, cleaning pressure P1 is constant in 0-0.4Mpa, heightened the second high-pressure pump pressure to setting value P2 every 2 minutes in the cleaning process, P2 is 0.8-4Mpa, read in the infiltration aquifer yield of reverse osmosis membrane under the P2 pressure after, again the second high-pressure pump pressure is recalled to former cleaning pressure P1 and proceeds to clean; Like this repeatable operation, the infiltration aquifer yield that obtains reverse osmosis membrane under the P2 pressure obtains the permeation flux regeneration rate over time;
5) after reverse osmosis membrane cleans half an hour, adopt the aquifer yield Jv of condition test reverse osmosis membrane after cleaning in the first step, calculate Jv/Jv0 thus, obtain the cleaning efficiency of gas-liquid mixture.
2. the pressurizing dissolved air flotation cleaning method of organic pollutant on reverse osmosis membrane according to claim 1 is characterized in that described reverse osmosis membrane is 8 inches of commercial diameters, 4 inches, 2.5 inches rolled film element, hollow fibre membrane component and flat membrane component.
3. the pressurizing dissolved air flotation cleaning method of organic pollutant on reverse osmosis membrane according to claim 1 is characterized in that described organic pollution is one or more in humic acid, alginates, protein, aliphatic acid, dissolved organic matter, the dissolubility microbial product.
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| CN106770403B (en) * | 2016-11-15 | 2020-07-14 | 中国科学院上海高等研究院 | Method for detecting influence of different pollutants on reverse osmosis membrane on performance of membrane device |
| CN106552512A (en) * | 2016-11-23 | 2017-04-05 | 德兰梅勒（北京）分离技术股份有限公司 | A kind of organic acid decolorization purification device |
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| CN107198970A (en) * | 2017-07-24 | 2017-09-26 | 金科水务工程(北京)有限公司 | A kind of full waterpower is made up a prescription Membrane cleaning system |
| CN114288865B (en) * | 2021-12-31 | 2022-09-20 | 河南同生环境工程有限公司 | Offline air vibration cleaning method for reverse osmosis membrane |
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