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Comparison of the advantages and disadvantages of reverse osmosis dry membrane and wet membrane

Update time : 2021-11-15 14:54:21

The difference in the use of reverse osmosis membranes: The manufacturing process of conventional aromatic polyamide reverse osmosis composite membranes is similar, that is, polyester non-woven fabric is used as the structural strength base layer, and a layer of high-permeability micro-layer is pre-coated on the non-woven fabric. The porous polysulfone is used as the support layer, and then the separation function layer of the ultra-thin film is formed by the interface recondensation method, which is generally a wet film. If a dry film is required, the wet film must also be fed into the drying unit. Therefore, the difference between the dry film and the wet film is that the dry film is made by drying the wet film.

The difference in the rolling process of the reverse osmosis membrane element: the membrane used in the dry membrane element is a dry membrane, and the membrane used in the wet membrane element is a wet membrane. There is no significant difference in the rolling process of the two.

The advantages of dry reverse osmosis membrane elements:

1. The manufacturing technology and equipment of dry-type membrane elements are relatively more complicated, but dry-type membrane elements do not require protective liquid or other special protective measures, are light in weight, relatively low in transportation costs, and have a longer storage time for membrane elements.

2. Because dry membrane elements are not humid, special vehicles are not needed for transportation below freezing point in winter, which is convenient for transportation and has low requirements for storage conditions.

Disadvantages of dry reverse osmosis membrane elements:

1. Sampling inspections are used before the membrane elements leave the factory. It cannot be guaranteed that the performance of the membrane elements of each factory will meet the standard, and there is the possibility of defects in the membrane elements that leave the factory.

2. The initial performance of the membrane element is low after it is installed in the system. It takes a long time to soak and rinse, and the performance of the membrane element can gradually reach the best state, which wastes time and flushing water.

3. The basic reverse osmosis performance of the membrane element, that is, the water production and the salt rejection rate are generally slightly lower than that of the wet membrane element.

The advantages of wet reverse osmosis membrane elements:

1. Wet-type reverse osmosis membrane elements are generally tested for the performance of each membrane element before leaving the factory, which can ensure that the performance of the membrane element of each plant reaches the standard, and eliminates the delivery of defective membrane element products.

2. The initial performance of the wet reverse osmosis membrane element is superior, and the best performance of the membrane element can be achieved after a simple flushing after on-site installation, saving start-up time and flushing water source.

3. The basic reverse osmosis performance of wet membrane elements is generally better than that of dry membrane elements, that is, membrane elements have a slight advantage in desalination rate and water production.

Disadvantages of wet reverse osmosis membrane elements:

1. Wet membrane elements need to use protective liquid or other protective measures. Membrane elements need to be kept moist and free from microbial contamination.

2. Since the membrane element is in a humid state, it is better to use insulated vehicles for transportation below the freezing point in winter or it needs to be stored in a place above the freezing point after arriving at the destination.

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