Precautions for the generation and maintenance of membrane pollution in brackish water desalination

Precautions for the generation and maintenance of membrane pollution in brackish water desalination equipment?

by:Ocpuritech     2021-03-21
Precautions for the generation and maintenance of membrane pollution in brackish water desalination equipment? Author: brackish water desalination equipment reverse osmosis membrane is very susceptible to contamination, once the contaminated water quality will affect the results. What is the cause of membrane pollution in brackish water desalination equipment? 1. Ion fouling During the reverse osmosis process, the less soluble salts such as CaCO3, CaSO4, BaSO4 in the feed water are concentrated, causing the concentration of these salts in the concentrated water to exceed the solubility to precipitate, resulting in sediments and staying on the surface of the membrane. And the formation of scale in the membrane pores makes the membrane contaminated, resulting in a decrease in the water permeability of the reverse osmosis device, a significant increase in pressure difference, and a rapid decrease in efficiency. 2. Silica precipitation The solubility of silica is affected by many factors, such as temperature and pH, and the maximum solubility of silica is usually 150mg/L, while the content of silica in many raw waters exceeds 20mg/L. Therefore, for operational safety, the concentration of silica in the concentrated water should be strictly controlled, and silica should not be allowed to precipitate on the reverse osmosis membrane during operation. 3. Deposition of metal oxides Groundwater often contains free ions such as iron and manganese. After they come into contact with air or oxidants, they can be oxidized into difficult sols and block the membrane pores, causing the pressure difference of the reverse osmosis membrane to rise and the water production to drop. 4. Suspended particles and colloidal pollution. When the security filter in the reverse osmosis water pretreatment system is short-circuited or malfunctions, the security filter loses its filtering function, and the suspended particles and colloids in the influent water cannot be removed, causing the suspended particles and colloids to be on the membrane surface. Amorphous precipitation is formed, which blocks the water inlet channel of the reverse osmosis membrane and causes the membrane to be contaminated. 5. The breeding of microorganisms The reverse osmosis membrane is an organic material, which itself can cause the breeding and reproduction of microorganisms. There are more organic substances (CODMn) in the reverse osmosis water, which will also promote the growth of organisms. If phosphorus-based scale inhibitors are added to the water, and the temperature of the reverse osmosis water supply is appropriate, the microorganisms will grow faster.
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