What is a UF membrane? Structure and application of UF

Water purifier is an extremely important device in modern life. Today, there are many different brands and types of water filters on the market. In particular, the UF membrane is a technological solution that brings high efficiency, is easy to operate, install and is suitable for the economic conditions of the majority of households.

What is a UF membrane?

UF stands for Ultrafiltration. The UF membrane is also known as the permeable hollow fiber ultrafiltration membrane.

The filter fiber of the UF membrane is white, the pore size is only from 0.1 to 0.001 micrometer, so it is easy to remove impurities and bring pure water, salt, and minerals through. To make it easy to imagine, the filter hole of the UF membrane is 5000 times smaller than that of a human hair, so most of the suspended substances in the water are removed in this process.

Structure and working principle of UF 

The UF membrane is composed of:

• Hollow, white filter fibers of Hydrophilic UPVC material.
• The outer shell and the filter element’s terminals and devices are made of Epoxy Resin or Stainless Steel.
• 3 ports with PVC valve: water inlet, waste water outlet and clean water outlet.

The process of filtering water through the UF membrane is carried out at normal temperature, with a pressure of 1.5 to 3 kg/m2. The water valves are closed and opened automatically according to the operating cycle of the filter.

Ultrafiltration membrane (UF) has 2 operating principles:

• From the outside to the inside – the filter layer is on the outside of the membrane: The source water is pushed from the outside, the filter tube will retain impurities and extract the purified water inside.
• From the inside out – the filter layer is inside the membrane: Contrary to the above principle, the source water is now pumped from the inside, the filter tube will retain impurities and extract the pure water to the outside.

Application of a UF membrane

UF membranes are not only used in household activities but also in industrial production.

Household UF membranes are used in:

• Household drinking water purifier.
• Whole house water filtration system.
• Plant watering system, aquarium water pump, …
• Pre-filtration system for RO machine.

In addition, industrial UF membranes are also applied to water supply systems for: chemical production, pharmaceuticals, beverage and food processing, wastewater treatment, etc.

What is the difference between UF membrane and RO membrane?

Both UF or RO membranes have their own advantages and disadvantages. To make it easier to analyze the difference, you can compare the following table:

COMPARISON TABLE OF UF MEMBRANE AND RO MEMBRANE

	UF Membrane	RO Membrane
Technology	Extracted through microfiber filter	Reverse osmosis across membranes
Structure	Membrane shell Fiber UF membrane 3 Valves to receive and discharge water Flowmeter Pressure gauges	Protective case Multiple stacked RO membranes Water shaft Isolation Gaskets
Filtering ability	Removes impurities larger than 0.001 micrometer. The water after filtration is relatively clean with a few minerals.	The filter mesh has a pore size as small as 0.0001 micrometer. Water after filtration is up to 95% pure and can be drunk directly
Working principle	Use pressure to push the water through the filter from the outside or inside. Purified water is obtained through each valve opening cycle.	Based on the principle of gradual osmosis through the membrane filter, pure water molecules are collected at the filter core.

Based on the comparison table above, it can be seen that the UF membrane does not remove impurities as well as the RO membrane. However, due to the principle of pressure extraction, the performance of UF membranes is higher. In addition, UF membranes also have outstanding features such as:

• Has a lifespan of 3 to 5 years, which is relatively high.
• Cheaper than other membranes.
• Consume less power.
• The installation and operation process is relatively simple.
• Does not discharge too much water, helping to save maximum water.

Efficiency of water samples after UF membrane filtration test

To easily visualize the cleaning ability of UF membranes, customers can refer to the results from the following 1 experiment:

WATER SAMPLE COMPARISON TABLE BEFORE AND AFTER FILTER THROUGH UF MEMBRANES

Parameters	Source water	Water after UF
Turbidity (NTU)	10,2 NTU	0,2 NTU
Phenol molecule	0,018 mg/l	<0,002 mg/l
CODcr	3,46 mg/l	1,46 mg/l
Chloroform	347 mg/l	4,5 mg/l
Intestinal Coliform	350 mg/l	0
Fecal Coliform	350 mg/l	0

In there:

• Phenol is a substance that is harmful to the body. If phenol is absorbed higher than 0.037mg/kg body weight, it will cause convulsions, coma, arrhythmia, drop in blood pressure, etc. and affect brain structure.
• CODcr is the chemical oxygen demand required to decompose organic and inorganic compounds in water. The higher the CODcr, the more impurities, microorganisms, etc. are present in the water.
• Chloroform is a chemical compound found in polluted water. This compound affects the human sense of smell, more dangerous, Chloroform can cause liver and kidney cancer if long-term exposure.
• Intestinal Coliform infection will cause the body to experience a number of conditions such as abdominal pain, fever, fatigue, digestive disorders. In addition, this is also a source of transmission of diseases from animals to humans.
• Fecal Coliform bacteria are often found in domestic wastewater, feces, etc. This is the source of infection of various diseases and causes symptoms such as vomiting, headache, fever, diarrhea, etc.

Hopefully, the above article has provided you with specific information about UF membranes. If there is a need to use or install water purification equipment, please contact Song Phung Environmental Company for the best advice!

Learn more: What is TDS in water? Using TDS to design water treatment system

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Translator: Duong Nguyen Hoang Khang