Can SO2 breed microorganisms to block reverse osmosis membranes?

1. General analysis.

According to my engineering experience, the process of pH adjustment of hydrochloric acid is very fast, and at such a low content (17-30ppm) and after dilution to adjust the pH value, the reaction between the two will be more difficult, even if the amount of reaction produced is very small. Therefore, there should be no need to worry about this;

Second, the application of the project.

Many engineering projects have added sodium bisulfite reducing agent after adding acid to adjust pH value, and there has not been a saying that "sulfur dioxide SO2 breeds microorganisms to plug the reverse osmosis membrane", so from a practical point of view, it should not be fouled by the reverse osmosis membrane.

3. Possible situation of the project.

According to the water quality provided, the inlet water quality of the system is relatively poor, so the operation of reverse osmosis may cause serious pollution, especially the inlet water of the system is wastewater after treatment (such as circulating water, reclaimed water reuse, etc.), after adding sodium bisulfite, there will be some viscous pollutants similar to yellowish, which is basically not brought by the reaction, mainly may be that some pollutants have flocculation, precipitation, polymerization and other phenomena after dosing and stick to the inner wall of the pipeline or the inlet section of the membrane. It should be checked from the pretreatment situation and the dosing situation.

If something is wrong, please advise! Thank you!

SO2 is sulfuric acid when dissolved in water, and microorganisms will be corroded.

It's hard to say about organic pollution, but if the water hardness is relatively high, it is dangerous.

What environmental conditions, equipment conditions.

No, no! This requires a catalyst and strong pressure. Don't believe you?

According to the technical information provided by the membrane manufacturer, the focus of the two anti-pollution membranes is different, and the anti-pollution concept of the anti-pollution membrane is to make the membrane wrinkled, which greatly increases the membrane area and increases the anti-pollution performance of the membrane (this is what I heard in the lecture a long time ago, not necessarily correct, please understand); The anti-fouling concept of Dow's anti-fouling film is to make the diaphragm the same as a mirror, and the contaminants are difficult to adhere to and increase the anti-fouling performance of the membrane.

Hyde Energy adopts the theory of electric neutrality and hydrophilic pollution resistance, and by changing the charge and hydrophilicity of the membrane surface, cationic and amphoteric pollutants are not easy to adsorb with the membrane.

The anti-fouling membrane element not only has the characteristics of low pressure, high flux and high desalination rate of the composite membrane, but also has the characteristics of hydrophilic and electrically neutral.

Usually there are many positively charged substances in wastewater and sewage, if they are in contact with the traditional reverse osmosis membrane element with negative charge on the surface, it is easy to adsorb on the surface of the membrane and cause pollution to the membrane element, which will lead to the decrease of water yield and desalination rate of the membrane system of the reverse osmosis system, increase the cleaning frequency of the system, and shorten the life of the reverse osmosis membrane element. Reverse osmosis systems with anti-fouling membrane elements can reduce the occurrence of such adsorption phenomena and thus play an anti-fouling role.

The most commonly used brands are Hydeneng, GE, and Dow, which account for more than 90% of the market; There are also some Japanese Toray and other ones that are rarely used.

Look at the change of the boy here, change the nuclear Hu.

The life of a reverse osmosis membrane is not measured by time, we have to look at its operating indicators, such as desalination rate, water production, etc. Of course, the longer it takes, the more its indicators will naturally decline. In order to extend its service life, system design and daily maintenance are very important, a good system design, the premise is to have objective data analysis of water source conditions, reasonable room rate.

In daily maintenance, pay attention to cleaning and decalcification and other operations. If you want to make the best use of the membrane and maximize the efficiency of the membrane, it should be checked regularly, and if it is found that the desalination rate and water yield indicators have decreased and cannot be restored through cleaning and disinfection, it must be replaced. If you have more questions, you are willing to learn together.

No. This has a certain impact on the membrane itself and the water quality. Water flux and water quality TDS value, etc. It cannot be used frequently, and it can be washed if it is not too long. Increase the amount of water throughput.

Cleaning method for reverse osmosis membrane contamination It is recommended to use a special cleaning solution for the membrane when cleaning the reverse osmosis membrane. It is very important to carry out chemical analysis of contaminants before determining the cleaning solution, and the detailed analysis and comparison of the analysis results can ensure the selection of the best cleaning agent and cleaning method, and the cleaning method and cleaning effect obtained during each cleaning should be recorded, so as to provide a basis for finding the best cleaning method under specific feed water conditions.

For inorganic contaminants, it is recommended to use a citric acid cleaning solution; For calcium sulfate and organic matter, it is recommended to use sodium tripolyphosphate and EDTA tetrasodium salt cleaning solution; For serious organic contamination, it is recommended to use sodium tripolyphosphate and sodium dodecylbenzene sulfonate cleaning solution. All cleaning solutions can be washed for up to 60 minutes at a maximum temperature of 104 degrees Fahrenheit (40 degrees Celsius), the amount of supplies required is measured in 100 gallons (379 liters), the cleaning solution is prepared in proportion to the chemicals and cleaning water, and the solution should be prepared and mixed with free chlorine-free reverse osmosis products.

Chemical cleaning and water flushing of reverse osmosis membrane elements During cleaning, the cleaning solution is circulated in the concentrated water channel of the membrane at low pressure and high flow, and the membrane element is still installed in the pressure vessel and a special cleaning device is required to complete the work.

General steps for cleaning reverse osmosis membrane elements:

1.Clean, free chlorine-free reverse osmosis product water is pumped from the cleaning tank (or equivalent water source) into the pressure vessel and discharged for a few minutes.

2.Prepare the cleaning solution in the cleaning chamber with clean product water.

3.Circulate the wash fluid in the pressure vessel for 1 hour or a pre-set time, with a flow rate of 35 to 40 gallons for 8 or 40 gallon minutes (133 to 151 liter minutes), 15 to 20 gallon minutes (57 to 76 liters for 6-inch pressure vessels), and 9 to 10 gallon minutes (34 to 38 liters for 4-inch pressure vessels).

4.After cleaning, drain and rinse the cleaning chamber, then fill the chamber with clean product water for further rinsing.

5.Use a pump to pump clean, chlorine-free product water from the cleaning tank or corresponding water source into the pressure vessel and discharge it for a few minutes.

6.After flushing the reverse osmosis system, run the reverse osmosis system with the product water drain valve open until the product water is clean, foam-free, or detergent-free (typically 15 to 30 minutes).

Three physical cleaning methods for Drammel reverse osmosis membranes!

Citric acid mixed with water. First, the cleaning liquid is backflushed from the permeate end. Forward again, repeat twice. The membrane can also be removed to soak.

Reverse osmosis cleaning needs to determine the cleaning plan according to the pollution source, organic matter fouling, microbial fouling, scaling component analysis, etc.

The focus is on adjusting the operating parameters and reducing the number of cleanings according to the occurrence of fouling.

1.When the reverse osmosis system does not suffer from serious pollution, but only regularly cleans the case, the conventional cleaning method is used immediately, which is also one of the methods to test the RO membrane after contamination, and is generally used first. There are generally two ways of cleaning, physical cleaning and chemical cleaning.

Physical cleaning of reverse osmosis membrane is the use of mechanical scouring to remove the pollutants in the membrane element, restore the performance of the membrane element, and sometimes use various physical methods such as full flow, vibration, gas-water mixing, until ultrasonic and other physical methods to flush out the adsorbed pollutants.

3.Chemical cleaning is the use of corresponding chemicals to react with contaminants to dissolve them in water, and then discharge the membrane element to restore the performance of the membrane element. Particle-like pollutants with low adsorption, such as mechanical impurity particles, sand particles, activated carbon, iron filings, etc., can be washed to achieve a certain effect, and it is difficult to achieve the expected effect by using the method of washing for pollutants with serious pollution or strong adsorption of glue.

When rinsing has made it difficult to remove contaminants, the grate should be stopped and chemically cleaned. In order to improve the effect of chemical cleaning, choosing the right cleaning agent is the key issue for successful cleaning.

Evaluation indexes and influencing factors of reverse osmosis membrane.

Evaluation indicators. Generally speaking, reverse osmosis membranes should have the following properties:

The permeability per unit area is large and the desalination rate is high;

The mechanical strength is good, and the compaction effect of the porous support layer is small;

Good chemical stability, resistance to acid, alkali corrosion and microbial erosion;

Uniform structure, long service life, slow performance decay;

It is easy to make film, cheap, and the raw materials are sufficient.

For detailed analysis, you can take a look at Hydenen's membrane**, reverse osmosis membrane technology support section...

Hydeneng's unanimous reputation is good.

Hyde Neng's reverse osmosis membrane is better.

Given the oxidizing nature of nitric acid, I think hypothesis 1 may be true.

Equation: 3AG2SO3+2HNO3=3AG2SO4+2NO +H2O

But I think the following reaction is probably a bit greater:

Sulfur dioxide is first dissolved in the solution, and the weak hydrogen ions ionized by sulfurous acid activate the oxidation of nitrate, so sulfite is oxidized to sulfate and forms silver sulfate precipitate with silver ions, and nitrate is reduced to nitric oxide. Because I remember hearing that when the redox reaction and the metathesis reaction exist at the same time, the redox reaction takes precedence. Reactive:

3so2+2h2o+2no3- =3so42- +4h+ +2no

2ag+ +so42- =ag2so4↓

If you can't understand it, you can think: if it is really Mr. silver sulfite, but silver sulfite is soluble in nitric acid and releases sulfur dioxide, so sulfur dioxide gas is oxidized in solution to become sulfate, and then with silver ions to form silver sulfate precipitation, and nitrate is still reduced to nitric oxide.

If your teacher said it, there is only one ion equation called 3SO2 + 2H2O + 2NO3- =3SO42- +4H+ +2NO (in fact, you should have asked the teacher directly at that time).

My understanding is that SO2 is a polar molecule, and water is also a polar molecule, similar to each other; And it can also form a certain amount of H2SO3 with water

Supplementary to the question: Hydrogen bonds are generally formed only by N, O, and F, that is, generally speaking, H bonds exist between the molecules of NH3, H2O, and Hf, and SO2 does not form hydrogen bonds when dissolved in water.

1.High solubility, 1:40

2.Soluble in water to form sulfurous acid.

There are many reasons for membrane blockage, water quality changes, pretreatment aging, improper operation, and system design defects.

It is recommended that you give a specific phenomenon, and then we will analyze it slowly. Such a general statement will not solve the problem.

For example, when you go to the doctor for a headache, you need to make a comprehensive diagnosis before you prescribe the right medicine.

It may be that your water source is different! Especially the water sources of the north! Hardness! It is also possible that the reverse osmosis membrane desalination rate is low! Such a situation! Or a technician! Check it out for yourself!

Performance requirements and indicators for reverse osmosis membranes.

In order to meet the needs of water treatment applications, reverse osmosis membranes must have the reliability of application and the economy of forming regularity, and its general requirements are as follows:

1. The permeability to water should be large and the desalination rate should be high.

2. It has a certain degree of strength and firmness, and will not be deformed or broken due to the pressure and tension of water. The membrane is compacted to the smallest possible extent and the water flux is attenuated, ensuring a stable water yield.

3. The structure should be uniform and can be made into the required structure.

4. It can adapt to large changes in pressure, temperature and water quality.

5. It has good temperature resistance, acid and alkali resistance, oxidation resistance, hydrolysis resistance, and biological pollution resistance.

6. The service life should be long.

7. The cost should be low.

The reverse osmosis membrane is blocked and cleaned. It's normal. Hydeneng provides reverse osmosis membrane cleaning solutions. You can refer to it.