Is there a grade of reverse osmosis membrane? Thank you

It should be said that there is still a difference.

The main indicator to measure the performance of reverse osmosis membranes.

Salt rejection rate. Desalination rate = (1 salt content of produced water salt content of inlet water) 100% The desalination rate of the membrane element has been determined at the time of its manufacturing and forming, and the desalination rate depends on the density of the ultra-thin desalination layer on the surface of the membrane element, the denser the desalination layer, the higher the desalination rate, and the lower the water production. The desalination rate of reverse osmosis for different substances is mainly determined by the structure and molecular weight of the substance, and the desalination rate of ** ions and complex monovalent ions can exceed 99%, such as monovalent ions

The desalination rate of sodium, potassium and chloride ions is slightly lower, but it can also exceed 98% (the longer the membrane is used, the more chemical cleanings are made, the lower the desalination rate of the reverse osmosis membrane.) ）；The removal rate of organic matter with a molecular weight greater than 100 can also be over 98%, but the removal rate of organic matter with a molecular weight less than 100 is lower.

Transmission speed. Water flux – refers to the water production capacity of a reverse osmosis system, i.e. the amount of water permeated through the membrane per unit of time, usually expressed in tonnes per hour or gallon-day. Salt permeability rate - the amount of salt permeable per unit time and per unit membrane area, also known as salt permeability and salt flux.

**Rate. **Rate – Refers to the percentage of feed water in the membrane system that is converted into permeate or permeate. It depends on the quality of the pretreated influent water and the water requirements. The rate of the membrane system has been determined at the time of design, **rate = (permeate flow rate inlet water flow) 100%.

Yes, in terms of operating pressure, there are high pressure, low pressure, ultra-low pressure, according to the appearance of the plate membrane, roll membrane, (now the general roll membrane is more used, because of his large area and small volume operation and application is convenient), according to the application of seawater desalination membrane and general tap water, river water purification membrane,,, according to the size of the four-inch membrane each eight-inch membrane.

In principle, there is no grade, no matter what products, including reverse osmosis membrane, nanofiltration membrane, ultrafiltration membrane, are suitable is the best.

The single-stage reverse osmosis and the two-stage reverse osmosis are usually referred to as the treatment process of the water treatment system.

What is a reverse osmosis membrane

Reverse osmosis membrane is an artificial semi-permeable membrane made of simulated biological semi-permeable membrane with certain characteristics, which is the core element to achieve reverse osmosis, generally made of polymer materials, and is widely used in large, medium and small water treatment systems. The diameter of the micropores on the surface of the reverse osmosis membrane is generally between, and the size of the permeability is related to the chemical structure of the membrane itself. Some polymer materials have good repulsion to salt, but the permeability of water is not good.

Some polymer materials have more hydrophilic groups in their chemical structures, so the permeability of water is relatively fast. In the development of modern industry, reverse osmosis membrane is recognized by the industry as the most economical and effective core component of membrane water treatment due to its excellent desalination performance, higher water yield, lower operating pressure and longer service life in the treatment of brackish water and seawater.

Reverse osmosis membrane features

1.Due to the large KW of the composite membrane, its working pressure is low, and the electricity consumption of the reverse osmosis feed pump is reduced by more than half compared with the cellulose acetate membrane.

2.The reverse osmosis membrane uses a new self-locking link technology that eliminates the risk of degradation of permeate water quality due to O-ring leakage.

3.The reverse osmosis membrane adopts fully automatic membrane rolling technology. Ensure that the filtration area of all membrane modules and the thickness of the inlet flow channel are the same, and the elements with accurate membrane area ensure the effective filtration area.

4.In the manufacturing process of reverse osmosis membranes, the membrane elements are not treated with any oxidizing chlorine. It reduces the occurrence of membrane performance degradation caused by oxidation on the membrane surface, and ensures the filtration effect.

4.The wider the inlet flow channel of the reverse osmosis membrane, the lower the operating cost, and the more relaxed the requirements of the system for the influent water quality and the abnormal working conditions of the pretreatment equipment.

The difference between the two is relatively simple. The equipment of reverse osmosis membrane filtration once is called first-stage reverse osmosis, and the water treated twice by reverse osmosis membrane is called second-stage reverse osmosis equipment. The difference between the two is relatively simple.

The equipment of reverse osmosis membrane filtration once is called first-stage reverse osmosis, and the water treated twice by reverse osmosis membrane is called second-stage reverse osmosis equipment. Generally, the conductivity of the first-class reverse osmosis equipment is about 30, and the second-level reverse osmosis equipment is below 10. Another difference between the two is that the process flow and equipment accessories of the manufacturing equipment are different, and the reverse osmosis equipment is a kind of equipment used to prepare pure water.

Raw water (tap water, groundwater, etc.) ) is filtered twice by reverse osmosis membrane to meet the standard of direct drinking water. The filtration accuracy of reverse osmosis membranes is microns, which can effectively remove colloids, bacteria and heavy metals in water.

In the production process of reverse osmosis equipment, whether the effluent is qualified or not is generally expressed by the conductivity of the hidden reed. Conductivity is not an instrument to measure the purity of water, but mainly to measure the ion content of water after reverse osmosis membrane filtration. The lower the content, the fewer ions will be in the filtered water.

Comparatively speaking, the higher the purity. Reverse osmosis equipment can be divided into first-stage reverse osmosis (single-stage reverse osmosis) and second-stage reverse osmosis equipment (two-stage reverse osmosis equipment) according to different manufacturing processes.

1. As far as the reverse osmosis membrane is concerned, in addition to the different types of membranes that may be used, they are all reverse osmosis membranes, such as the first-stage reverse osmosis membrane adopts brackish water membrane, and the second-stage reverse osmosis membrane adopts ultra-low pressure and high desalination rate membrane.

2. The difference between primary and secondary levels. In layman's terms, the raw water passes through a reverse osmosis device, which is divided into produced water and concentrated water, and this device is called the first stage; If the inlet water of another set of reverse osmosis device is the permeate of the previous reverse osmosis, or the first-stage permeable water cannot meet the requirements, and then it is treated by the first-stage reverse osmosis, and the latter reverse osmosis device is called the second stage.

Hope that clarifies it! Thank you

Generally, it should be considered from three aspects: desalination rate, water yield and specifications.

1. Select according to the water production.

Water yield refers to the amount of water permeable to the RO reverse osmosis membrane per unit time after the use of the reverse osmosis system. Therefore, when choosing the model of RO reverse osmosis membrane, we should pay attention to this parameter of the selected membrane type, and also consider the actual water demand.

2. Select the type according to the size and specification of the membrane element.

This is mainly due to the design of the reverse osmosis equipment system, if the reverse osmosis system is designed with a 4-inch membrane, then only a 4040 specification reverse osmosis membrane can be selected, if it is an 8-inch or other size membrane shell, then it is necessary to choose the appropriate model or replace the membrane shell.

3. Select the type according to the desalination rate.

The denser the desalination layer on the surface of RO reverse osmosis membrane, the higher the desalination rate, but since the desalination rate of RO reverse osmosis membrane has been determined at the time of manufacturing, we should fully understand what the selected membrane desalination rate is when purchasing RO reverse osmosis membrane models, and what is the desalination rate required by yourself, and select according to the matching between the two.

4. Select the model according to the best rate.

The rate is the percentage of water converted into permeate or permeate and is based on the quality and water requirements of the pre-treated influent in the reverse osmosis system. Therefore, if you want to buy a suitable RO reverse osmosis membrane model, you must fully understand how much the larger and smaller ** rate can reach, and whether it can meet the needs of the enterprise's permeate use.

When selecting and using reverse osmosis membranes, it is necessary to understand and master the physical and chemical properties of the membrane and the separation characteristics of the membrane. (1) Chemical stability of the membrane: The chemical stability of the membrane mainly depends on the anti-oxidation and hydrolysis properties of the membrane, which depends not only on the chemical properties of the membrane itself, but also on the properties of the separating fluid.

Usually the aqueous solution contains oxidizing substances such as sodium hypochlorite, dissolved oxygen, hydrogen peroxide and hexavalent chromium, which are easy to produce active free radicals and carry out chain initiation reaction and chain transfer reaction with polymer membrane materials, resulting in the oxidation of the membrane and affecting the performance and life of the membrane. In addition, when the hydrolysis and oxidation of the membrane are carried out at the same time, when the polymer backbone used for molding contains hydrolyzed chemical groups - conh-,-coor-,-CN2-O-, etc., these groups are prone to hydrolysis and degradation reaction under the action of acid or alkali, so that the performance of the membrane is damaged. (2) Heat resistance and mechanical strength of the membrane:

In addition, the improvement of the heat resistance of the membrane means that the solution with higher temperature can be separated, the increase of the temperature of the solution, the increase of the water permeability rate, and the mass transfer coefficient and the permeability coefficient of salt on the high pressure side of the membrane also increase slightly. Therefore, membrane materials with good heat resistance should be selected as much as possible, and the properties of the solution to be measured, the use time and the requirements for membrane properties should be considered in use.

How to choose the type of reverse osmosis membrane?1. Select the model of the membrane according to the inlet water quality of the membrane

Inlet TDS 1000ppm can be used for ultra-low pressure membrane element inlet

3000ppm TDS 1000ppm can be selected with anti-fouling membrane element inlet water;

TDS 3000ppm can be used with brackish water desalination membrane elements;

The influent TDS 5000ppm can be selected with seawater desalination membrane elements.

2. Select the membrane element according to the water yield (consider choosing a large membrane or a small membrane):

In general, 4040 membrane elements are mostly used for HIDENENG reverse osmosis equipment with a water yield of < 4t hFor reverse osmosis equipment per ton hour, select 1 membrane of 4040, 2 membranes per ton hour, 4 reverse osmosis per ton hour, and so on.

Hyde can reverse osmosis equipment with a water yield of 4t h mostly uses 8040 membrane elements. The 8040 membrane element is about 1 ton per hour, and 4 8040 membrane elements are selected for the 4 ton hour reverse osmosis equipment.

How to choose the model of reverse osmosis membrane, in general, 4040 membrane elements are mostly used for reverse osmosis equipment with a water yield of 4t h;For reverse osmosis equipment per ton hour, select 1 membrane of 4040, 2 membranes per ton hour, 4 reverse osmosis per ton hour, and so on.

In order to let customers better understand the reverse osmosis equipment, introduce the selection of the reverse osmosis membrane model 1, and select the membrane model according to the influent water quality of the membrane

Inlet TDS 1000ppm can be selected ultra-low pressure membrane element inlet water 3000ppm TDS 1000ppm can be selected anti-pollution membrane element inlet TDS 3000ppm can be selected brackish water desalination membrane element inlet TDS 5000ppm can be selected seawater desalination membrane element 2, according to the water production to select the membrane element (consider the choice of large membrane or small membrane):

In general, 4040 membrane elements are mostly used for reverse osmosis equipment with a water yield of 4t h; For reverse osmosis equipment per ton hour, select 1 membrane of 4040, 2 membranes per ton hour, 4 reverse osmosis per ton hour, and so on.

The reverse osmosis equipment with a water yield of 4t h mostly uses 8040 membrane elements. The 8040 membrane element is about 1 ton per hour, and 4 8040 membrane elements are selected for the 4 ton hour reverse osmosis equipment.

Reverse osmosis membranes should have the following characteristics:

1) It should have an efficient desalination rate at high flow rate;

2) It has high mechanical strength and service life;

3) It can function at lower operating pressures;

4) Able to tolerate the effects of chemical or biochemical effects;

5) It is less affected by pH value, temperature and other factors;

6) The raw materials for film making are easy, easy to process, and low cost.

Main performance indicators of reverse osmosis:

1. Desalination rate: Under normal circumstances, the desalination rate is above 98%, and the salt penetration rate is 1 - desalination rate = 1-98% = 2%.

2. Water permeability: generally the design flux of first-level reverse osmosis is 8-14gfd, the design flux of second-level reverse osmosis is 20-30gfd, 1gfd =, the water yield of a single membrane element = membrane area * design flux, such as 400ft2, that is, the design flux is 14gfd, then the permeability of this membrane is.

3. Increase in salt permeability: 10% per year, if the salt permeability rate in the first year is 2% and the desalination rate is 98% at this time, then the salinity permeability rate in the second year is 2% * (1 + 10% + =, the desalination rate at this time.

4. Water attenuation: 7% per year, the calculation method is the same as above.

5. ** rate. That is, the conversion rate of the water supply to the permeate directly affects the cost of the desalination system. For bitter saline, the ** rate is about 90%; High bitter saline water reduced to 60% to 65%; The rate of industrial seawater systems** is 35% to 45%.

6. Membrane flux. is the velocity of water flow through a specific area of the membrane surface.

1. The above performance is based on the detection data after 30 minutes of operation under the following test conditions: NaCl concentration: 200mg L, pressure 60psi, ** rate 15%, temperature 25,.

2. The minimum desalination rate is 96%.

3. The vacuum leakage test of dry membrane elements is based on the San Diego regulations, and its performance is also stable.

4. The possible variation range of water yield of a single element is 20%.

5. All membrane elements are packaged in vacuum and independent cartons, and 1% sodium bisulfite protective solution is injected into the wet membrane elements. All dry film products are packaged in polyethylene bags without vacuum.