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UF membrane technology and filtration principle

Author: Site Editor     Publish Time: 2022-09-23      Origin: Site


Ultrafiltration (UF) technology is a membrane separation technology between microfiltration and nanofiltration, with an average pore size of 3~100 nm, and has the function of purification, separation and concentration of solutions. Its retention mechanism mainly consists of membrane sieving and electrostatic effect, the filtration medium is ultrafiltration membrane, driven by the pressure difference between the two sides, only low molecular weight solutes and water can pass through the ultrafiltration membrane, so as to achieve the purpose of purification, separation and concentration. There are about 6 billion micro-pores of 0.01 micron on the wall of each metre of ultrafiltration membrane filament, whose pore size only allows water molecules, beneficial minerals and trace elements in water to pass through, while smaller bacteria are above 0.02 micron in size, so bacteria as well as colloids, rust, suspended matter, sediment and macromolecular organic matter, which are much larger than bacteria, can be retained by the ultrafiltration membrane, thus realising the purification process.

Ultrafiltration membrane technology is used in a wide range of applications. The first ultrafiltration membranes used were natural animal organ films, and initially ultrafiltration remained undeveloped as an experimental work until the 1970s, when ultrafiltration technology entered a phase of rapid development for industrial applications. At present (2018), ultrafiltration membrane materials have expanded from cellulose acetate (CA) to polystyrene (PS), polyvinylidene fluoride (PVDF), polycarbonate (PC), polyacrylonitrile (PAN), polyethersulfone (PES) and nylon (PA), with MWCOs developing from 103 to 106. because ultrafiltration has simple equipment, small footprint, constant phase state, low operating pressure, low Because of its simple equipment, small footprint, constant phase, low operating pressure, low material requirements, simple equipment and other characteristics, its application range also extends rapidly from research to practical applications, such as electronics, medicine, electrophoresis paint, beverages, food and chemical, medical and wastewater treatment and recycling, etc.

1. The water production process of ultrafiltration membrane

Tap water first enters the ultrafiltration membrane tube, under the action of water pressure difference, many 0.01 micron micro-pores on the surface of the membrane only allow water molecules, beneficial minerals and trace elements through, become purified water. Bacteria, rust, colloid, sediment, suspended matter, macromolecular organic matter and other harmful substances are retained in the ultrafiltration membrane tube and discharged when the ultrafiltration membrane is flushed.

2. Ultrafiltration membrane flushing process

After the ultrafiltration membrane has been used for a period of time, the bacteria, rust, colloid, suspended matter, macromolecular organic matter and other harmful substances retained will adhere to the inner surface of the ultrafiltration membrane, so that the water yield of the ultrafiltration membrane gradually decreases, especially when the tap water quality is seriously polluted, it is more likely to cause clogging of the ultrafiltration membrane, and regular flushing of the ultrafiltration membrane can effectively restore the water yield of the membrane.

water treatment

3. Ultrafiltration membrane cartridge

The bundled ultrafiltration membrane is made into an ultrafiltration cartridge after casting process as shown below. The cartridge consists of ABS shell, epoxy head at both ends of the shell and bundled ultrafiltration membrane. The epoxy head fills the gap between the membrane filament and the membrane filament, forming an isolation between the original liquid and the permeate. The original liquid first enters the pore of the ultrafiltration membrane and becomes the permeate after being filtered by the ultrafiltration membrane, preventing the original liquid from entering the permeate directly without filtration.

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