A Comprehensive Analysis of Ultrafiltration Membrane Technology: From Principles to Applications

Definition and Working Principle of Ultrafiltration Membranes

Ultrafiltration membranes, among the earliest developed polymeric membranes, have their nominal pore size precisely controlled within the range of 0.01 to 0.2 micrometers. What sets these microporous filtration membranes apart is their unique filtration mechanism: when appropriate pressure is applied to one side of the membrane, solvents and certain low-molecular-weight solutes in the solution can pass through the membrane’s tiny pores and permeate to the other side, while higher-molecular-weight solutes—or even certain emulsified micelle aggregates—are efficiently retained on the original side, effectively achieving filtration and separation.

In the field of water treatment, ultrafiltration membrane technology has demonstrated outstanding filtration performance. With a filtration accuracy as high as 99%, it effectively removes a wide range of harmful substances from water while minimizing or eliminating the need for chemical additives. This not only prevents secondary contamination of the water but also ensures that the treated water is exceptionally pure. Additionally, the technology is easy to operate—ultrafiltration-based systems are highly automated, requiring just two simple actions: turning them on and off. Thanks to the superior chemical stability of ultrafiltration membrane materials, these membranes can withstand both acid and alkali corrosion and even endure high temperatures, making them ideal for advanced sterilization and disinfection processes. As a result, this technology boasts an incredibly broad range of applications.

Applications of Ultrafiltration Membranes

Oil-Containing Wastewater Treatment

Oil-containing wastewater primarily originates from crude oil spills, slaughterhouse effluents, and domestic sewage, among other sources. It typically includes components such as floating oil, dispersed oil, emulsified oil, and heavy oil. While grease traps are commonly used as a treatment device, they often struggle to effectively handle emulsified oil. To address this challenge more efficiently, air flotation is frequently employed as an auxiliary method. Given that emulsified oil molecules are relatively large, ultrafiltration membrane technology proves highly effective under pressurized conditions, trapping emulsified oil along with other large-molecule contaminants on the membrane’s exterior—and thereby significantly enhancing removal efficiency.

Urban wastewater reuse

Facing growing urban water demand, wastewater reuse has emerged as a crucial solution strategy. Treated domestic wastewater that meets reuse standards can be effectively utilized for urban landscaping and in municipal reclaimed water systems. Ultrafiltration membrane technology plays a pivotal role in this process, enabling rapid and efficient treatment of urban sewage to achieve compliance with reuse criteria. Given the typically favorable biochemical properties of urban wastewater, the CASS (Cyclic Activated Sludge System) process is often combined with ultrafiltration membrane technology in practical applications. Under a hydraulic retention time of 12 hours, this approach achieves a COD removal rate exceeding 86% and an ammonia nitrogen removal rate surpassing 90%, while maintaining the effluent pH within the range of 25 to 89—fully meeting the stringent standards for urban water reuse.