Difference Between RO Membrane and UF Membrane

Concept of RO membrane and UF membrane

A RO membrane is an artificial semi-permeable membrane with certain characteristics that mimics a biological semi-permeable membrane. Generally, they are made of high polymer materials such as cellulose acetate membrane, aromatic polyamide membrane, and aromatic polysulfone membrane. Some high polymer materials have good salt-rejecting properties but do not have good water permeability. Some high polymer materials have a chemical structure that has a relatively large number of hydrophilic groups, which results in a relatively faster water permeation rate.

An UF membrane is a microfiltration membrane with a uniform pore size and a nominal pore size range of 0.001 to 0.02 micrometers. By applying appropriate pressure on one side of the membrane, solute molecules that are smaller than the pore size can be screened out, and particles with a molecular weight greater than 500 daltons (atomic mass units) and a particle size greater than 10 nanometers can be separated. The UF membrane was one of the earliest developed high polymer separation membranes, and UF devices were industrialized in the 1960s.

Characteristic differences between RO membrane and UF membrane

RO membranes should have the following features: have high desalination efficiency under high flow rate; have high mechanical strength and service life; be able to function at low operating pressures; be able to withstand the effects of chemical or biochemical reactions; be less affected by factors such as pH value and temperature; have easily sourced membrane materials, simple processing, and low cost.

UF membrane application characteristics: no qualitative changes occur during the UF process, and it can operate stably at room temperature; UF membrane equipment has a sophisticated structure, small footprint, and is easy to operate; UF separation process is simple, and the equipment has a high degree of automation; it can classify substances of different molecular weights; UF membranes have strong applicability to water quality and a wide range of applications.

Application scope of RO membrane and UF membrane

The application scope of RO membranes includes fields such as power, petrochemical, steel, electronics, medicine, food and beverage, municipal and environmental protection. They play an important role in sea and brackish water desalination, boiler feedwater, industrial pure water and electronic-grade ultrapure water preparation, the production of drinking pure water, wastewater treatment, and special separation processes.

The application scope of UF membranes includes: pretreatment for RO and terminal treatment for ultrapure water in pure water and ultrapure water preparation processes; separation of bacteria, heat sources, colloids, suspended impurities, and large molecular organic matter in industrial water treated with UF membranes; purification of drinking water and mineral water; concentration, purification, and clarification in industries such as UF membranes in the fermentation, enzyme preparation, and pharmaceutical industries; separation, concentration, and clarification in industries such as soybean, dairy, sugar, wine, tea, vinegar, etc.; purification and recycling of industrial wastewater and domestic sewage; and recovery of electrophoretic paint.