21. Can reverse osmosis remove microorganisms such as viruses and bacteria?

Reverse Osmosis (RO) is very dense and has a very high removal rate of viruses, phages and bacteria, at least 3log or more (removal rate>99.9%). However, it should also be noted that in many cases, microorganisms may still breed on the water-producing side of the membrane, which mainly depends on the method of assembly, monitoring and maintenance, that is, the ability of a certain system to remove microorganisms is critically determined by the method of assembly, monitoring and maintenance. It depends on the proper system design, operation and management, not on the nature of the membrane element itself.

22. Should I use reverse osmosis process or ion exchange process for general influent water?

Under many water inlet conditions, the use of ion exchange resin or reverse osmosis is technically feasible, and the choice of process should be determined by economic comparison. In general, the higher the salt content, the more economical the reverse osmosis. The lower the amount, the more economical the ion exchange. Due to the widespread popularity of reverse osmosis technology, the use of reverse osmosis + ion exchange process or multi-stage reverse osmosis or reverse osmosis + other deep desalination technology combination process has become a recognized technical and economic more reasonable water treatment program, if you need to Understand, please consult the representative of the water treatment engineering company

23. How to remove silicon from water?

Silicon in water exists in two forms, active silicon (monomer silicon) and colloidal silicon (multiple silicon):
Colloidal silicon does not have the characteristics of ions, but the scale is relatively large. Colloidal silicon can be intercepted by fine physical filtration processes, such as reverse osmosis, and the content of water can also be reduced through coagulation techniques, such as coagulation clarifiers, but those need to rely on Separation techniques with ionic charge characteristics, such as ion exchange resins and continuous electrodeionization (CDI), have very limited effects on the removal of colloidal silicon.
The size of active silicon is much smaller than that of colloidal silicon, so most physical filtration techniques such as coagulation clarification, filtration and air flotation cannot remove active silicon. The processes that can effectively remove active silicon are reverse osmosis, ion exchange and Continuous electrodeionization process.

24. What effect does pH have on removal rate, water production and membrane life?

The corresponding pH range of reverse osmosis membrane products is generally 2-11. pH has little effect on the membrane performance itself. This is one of the significant characteristics different from other membrane products. However, the characteristics of many ions in the water are greatly affected by pH. For example, when weak acids such as citric acid are mainly in a non-ionic state under low pH conditions, they dissociate and become ionic under high pH values. Because the same ion has a high degree of charge, the removal rate of the membrane is high, and the removal rate of the membrane is low if the charge level is low or no charge. Therefore, pH has a huge impact on the removal rate of certain impurities.

25. What is the relationship between influent TDS and conductivity?

When the influent conductivity value is obtained, it must be converted into a TDS value so that it can be input in the software design. For most water sources, the ratio of conductivity/TDS is between 1.2 and 1.7. In order to carry out ROSA design, use 1.4 ratio for seawater and 1.3 ratio for brackish water for conversion, usually a good approximate conversion rate can be obtained.

26. How do I know if the membrane has been contaminated?

The following are the common symptoms of pollution:
Under standard pressure, water production drops
In order to achieve the standard water production, the operating pressure must be increased
Increased pressure drop between feed water and concentrated water
The weight of the membrane element increases
Obvious change in membrane removal rate (increased or decreased)
When the element is taken out from the pressure vessel, pour water on the water inlet side of the erected membrane element. The water cannot flow through the membrane element and only overflows from the end surface (indicating that the water inlet channel is completely blocked).

27. When should I choose membrane elements with low energy consumption or very low energy consumption?

Dow FILMTEC’s low energy consumption membrane elements are LE and LP types, and the extremely low energy consumption is XLE. They are used for customers who require the lowest energy consumption while still achieving high salt rejection and water production as their main purpose. For example, the energy consumption of our extremely low-energy XLE is only 50% of the corresponding energy consumption of standard BW products, but the salt rejection rate is low. Please consult a Dow representative or refer to product specifications.

28. What is the relationship between influent TDS and conductivity?

When the influent conductivity value is obtained, it must be converted into a TDS value so that it can be input in the software design. For most water sources, the ratio of conductivity/TDS is between 1.2 and 1.7. In order to carry out ROSA design, use 1.4 ratio for seawater and 1.3 ratio for brackish water for conversion, usually a good approximate conversion rate can be obtained.

29. How do I know if the membrane has been contaminated?

The following are the common symptoms of pollution: 1 Under the standard pressure, the water production volume drops; 2 In order to reach the standard water production volume, the operating pressure must be increased; 3 The pressure drop between the inlet water and the concentrated water increases; 4 The weight of the membrane element increases; 5 Membrane The removal rate changes significantly (increased or decreased)
When the element is taken out from the pressure vessel, pour water on the water inlet side of the erected membrane element. The water cannot flow through the membrane element and only overflows from the end surface (indicating that the water inlet channel is completely blocked).

30. When do I need to detect the membrane system and how to do it?

The reduction in the desalination rate of the system may be the uniform change of the elements, or it may be limited to a few membrane elements at the front or end. It may be the failure of each pressure vessel in the entire system, or it may be limited to a few pressure vessels. Therefore, it is necessary to determine the TDS value of the water produced by a single pressure vessel and the performance of a single membrane element. Please refer to the relevant chapters of this manual to understand the performance detection method of the membrane element.

Vontron LP21-4040 RO membrane

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