Application of membrane technology (such as reverse osmosis membrane, ultrafiltration membrane) in water treatment

Membrane technology, especially reverse osmosis membrane (RO membrane) and ultrafiltration membrane (UF membrane), is widely used in water treatment, especially in drinking water treatment and industrial wastewater treatment, playing an important role.

1. Reverse osmosis membrane (RO membrane)

Principle:
Reverse osmosis membrane uses the filtration principle of a semi-permeable membrane to remove impurities such as dissolved salts, heavy metals, organic matter, and microorganisms in water by using the osmotic pressure difference of water to obtain relatively pure water. This technology requires external pressure (usually the pressure of a water pump) to push water through the membrane pores.

Application areas:
Drinking water treatment: Reverse osmosis membrane can effectively remove inorganic salts (such as sodium, calcium, magnesium, chloride ions, etc.), organic matter, bacteria, viruses and other impurities in water. It is a common technology for drinking water purification, especially seawater desalination and groundwater treatment.
Industrial wastewater reuse: Many industrial fields (such as chemical, electronic, pharmaceutical and other industries) contain a large amount of soluble salts and toxic substances in wastewater. Reverse osmosis membranes can effectively remove these pollutants and realize wastewater reuse.
Improved water quality after wastewater treatment: After municipal sewage treatment, RO membranes can further purify water quality to meet the needs of industrial reuse or agricultural irrigation.
Advantages:
Good removal effect: It has high efficiency in removing most dissolved substances (including salts, heavy metals, etc.).
Wide application: It can treat various water sources, including seawater, brackish water, groundwater, etc.
Disadvantages:
High energy consumption: Reverse osmosis requires a higher operating pressure and consumes more energy.
Membrane pollution problem: It is easily contaminated by organic matter, bacteria, etc. and needs to be cleaned regularly.

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2. Ultrafiltration membrane (UF membrane)
Principle:
Ultrafiltration membrane is a filter membrane with pore size as the standard, and its pore size is usually between 0.01 and 0.1 microns. It mainly removes macromolecular substances, suspended matter, bacteria, viruses, etc. in water through the principle of physical filtration, but does not remove dissolved salts and low molecular substances.

Application areas:
Drinking water pretreatment: Ultrafiltration membrane is often used as a pretreatment link before reverse osmosis membrane to remove suspended matter, sediment, organic matter, etc. in water and protect the reverse osmosis membrane from pollution.
Wastewater treatment: In industrial wastewater treatment, ultrafiltration membrane can remove large particle impurities, grease, suspended matter, etc. in water, and is one of the common technologies in wastewater reuse.
Food and beverage industry: used for filtering liquids such as milk and juice to remove bacteria, yeast and other microorganisms.
Water resource recovery and reuse: In many industrial fields, ultrafiltration membranes are used for wastewater reuse, especially when the water quality is relatively clean, such as cooling water treatment, chemical wastewater treatment, etc.
Advantages:
Low energy consumption: Compared with reverse osmosis membranes, ultrafiltration membranes have lower energy consumption and do not require high pressure operation.
Easy operation and maintenance: The cleaning cycle of ultrafiltration membranes is longer, the membrane is less polluted, and the operation and maintenance are relatively simple.
Retain minerals: Ultrafiltration membranes do not remove minerals from water, maintaining the natural composition of water.
Disadvantages:
Limited removal effect: For dissolved salts, dissolved organic matter, and small molecules in water, the removal effect is poor, and it is not suitable for occasions requiring high-purity water.
Membrane pore blockage: The pore size of ultrafiltration membranes is large, so they may be affected by larger particle impurities and need to be cleaned regularly.