The filtration method of ultrafiltration membranes
Ultrafiltration membrane technology is a membrane separation technology based on screening and filtration, with pressure difference as the main driving force. The main principle is to create a tiny pressure difference on both sides of the filter membrane, providing the driving force for water molecules to pass through the small pores of the filter membrane and blocking impurities on the other side of the filter membrane, ensuring that the treated water quality meets relevant standards.
Generally speaking, ultrafiltration membranes can be classified into internal pressure ultrafiltration membranes and external pressure ultrafiltration membranes based on the different ways of water inflow. The internal pressure ultrafiltration membrane technology first injects wastewater into a hollow fiber membrane, and then pushes the pressure difference to make water molecules seep out of the membrane, while impurities remain inside the hollow fiber membrane. The external pressure ultrafiltration membrane technology is the opposite of the internal pressure. Under the push of pressure, water molecules penetrate the hollow fiber membrane, while other impurities are blocked outside.
Ultrafiltration membranes play an important role in the application of ultrafiltration membrane technology. Ultrafiltration membranes are mainly made of materials such as polyacrylonitrile, polyvinylidene fluoride, polyvinyl chloride, and polysulfone. The properties of these materials determine the characteristics of ultrafiltration membranes. In the practical application process, relevant operators need to fully consider factors such as temperature, operating pressure, water production volume, and water purification effect, to maximize the performance of ultrafiltration membrane technology and achieve the conservation and recycling of water resources.
At present, the application of ultrafiltration membrane technology usually has two filtration methods: dead-end filtration and cross-flow filtration. Dead-end filtering is also known as full filtering. When the suspended solids, turbidity and colloidal content of the raw water are relatively low, such as in tap water, groundwater, surface water, etc., or when there is a strict pretreatment system design before ultrafiltration, ultrafiltration can adopt the full filtration method for operation. During full filtration, all water passes through the membrane surface to become product water, while all pollutants are retained on the membrane surface. It needs to be discharged from the membrane module through regular air washing, backwashing and forward washing with water, as well as regular chemical cleaning. In addition to dead end filtering, cross-flow filtering is also a relatively common filtering method. When the suspended solids and turbidity of the raw water are relatively high, such as in reclaimed water reuse projects, cross-flow filtration is usually adopted. During cross-flow filtration, a portion of the feed water passes through the membrane surface to become product water, while the other part is discharged as concentrated water or returned to the membrane after being re-pressurized in a circulation mode. Cross-flow filtration enables water to circulate continuously on the membrane surface. The high-speed water flow prevents the aggregation of particles on the membrane surface, reduces the influence of concentration polarization, and alleviates the rapid fouling of the membrane.
Although ultrafiltration membrane technology has incomparable advantages in application, this does not mean that in the process of wastewater resource treatment, ultrafiltration membrane technology can only be used alone to purify wastewater. In fact, when confronted with the issue of treating polluted water resources, relevant personnel can attempt to flexibly combine various treatment technologies. Effectively enhance the treatment efficiency of contaminated water resources to ensure the quality of treated water resources is effectively guaranteed.
Due to the different causes of water pollution, not all polluted water resources are suitable for the same type of pollution treatment. Staff members should enhance the rationality of the ultrafiltration membrane technology combination and select the most suitable water purification treatment method. Only in this way can the quality of the purified sewage be further improved while ensuring the efficiency of water pollution control.
2026
