As industrialization and urbanization advance, a variety of complex and persistent emerging pollutants (EPs)-such as antibiotics, endocrine-disrupting chemicals, microplastics, and per- and polyfluoroalkyl substances (PFAS)-are increasingly found in the environment. These contaminants are persistent, bioaccumulative, and toxic, posing risks to ecosystems and human health. Membrane Separation Technology (MST) has emerged as a promising solution due to its high efficiency, low energy consumption, and sustainability.
1. Limitations of Conventional Treatments and the Rise of Membrane Separation
Conventional physical, chemical, and biological treatment processes are often ineffective against trace or highly stable pollutants. Activated sludge systems fail to remove pharmaceutical residues, while chemical oxidation may generate harmful byproducts. In contrast, membrane separation relies on selective physical permeation, enabling precise separation of contaminants without chemical alteration.
2. Applications of Membrane Separation in Emerging Pollutant Control
Nanofiltration (NF) and Reverse Osmosis (RO) membranes effectively remove antibiotics, hormones, and pharmaceutical residues from wastewater. Studies show that RO membranes achieve over 95% removal efficiency. Combined with biological treatment, MBR systems (Membrane Bioreactors) are now widely used in hospital and pharmaceutical wastewater treatment.
Ultrafiltration (UF) and Microfiltration (MF) membranes effectively capture microplastics smaller than 1 μm, preventing their discharge into aquatic environments. With surface modification and backwash systems, fouling can be reduced and membrane lifespan extended.
PFAS, known as "forever chemicals," are resistant to degradation. RO membranes with dense polyamide layers achieve PFAS removal rates above 90%. Advanced nanofiltration for PFAS treatment has become a major research and application direction globally.
Beyond pollutant removal, membranes also enable resource recovery. In acidic metal wastewater, acid-resistant nanofiltration and RO hybrid systems can separate metal ions and recover acids, providing both environmental and economic benefits.
3. Challenges and Innovations
While membrane separation offers significant advantages, challenges such as fouling, energy demand, and material durability persist. Future developments include:
- Novel membrane materials using graphene, MXene, and photocatalytic coatings for higher selectivity and fouling resistance.
- Integrated systems combining adsorption, oxidation, and biodegradation for synergistic removal.
- AI-driven monitoring for predictive maintenance and membrane health management.
- Energy-efficient design, developing low-pressure, high-flux membranes to optimize RO membrane wastewater reuse systems.
