Water treatment by membrane filtration is one of the most reliable treatment process in water purification. However, microbial biofouling is one of the major obstacles for achieving high permeability and high purity over a long-time operation. Microbial biofouling on the water filtration membrane is a main risk for public health due to the recontamination by pathogenic bacteria, viruses and fungi in the biofouling.

This work provides a solution to resist microbes growing by developing anti-microbial and anti-adhesion coating which can reduce bacteria survive in filtration setup and prevent adhesion of microbes.

Quaternary ammonium cation is known to have a good bactericidal ability and zwitterionic compound is a good surfactant for anti-adhesion. Here 2-(diethylamino)ethyl meth...[ Read more ]

Water treatment by membrane filtration is one of the most reliable treatment process in water purification. However, microbial biofouling is one of the major obstacles for achieving high permeability and high purity over a long-time operation. Microbial biofouling on the water filtration membrane is a main risk for public health due to the recontamination by pathogenic bacteria, viruses and fungi in the biofouling.

This work provides a solution to resist microbes growing by developing anti-microbial and anti-adhesion coating which can reduce bacteria survive in filtration setup and prevent adhesion of microbes.

Quaternary ammonium cation is known to have a good bactericidal ability and zwitterionic compound is a good surfactant for anti-adhesion. Here 2-(diethylamino)ethyl methacrylate and [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt were used as antimicrobial and anti-adhesion agents respectively. Poly (ethylene glycol) diacrylate (PEGDA) was chosen to form a strong cross-linked copolymer coating with the antimicrobial and anti-adhesion agents on the water filtration membrane. The membrane with antimicrobial and anti-adhesion coating is challenged with a high concentration of E.coli in water. High disinfection ability was obtained in the liquid disinfection test. The coating was characterized by FTIR, TOF-SIMS and XPS elementary analysis. SEM was applied for biofouling observation. The result shows that structure of the water filter membrane is beneficial to the biofilm formation, and the membrane with anti-adhesion coating can reduce the biofouling with the charged surface from zwitterionic polymer coating.

Antimicrobial and anti-adhesion coating were further combined as a two-level antimicrobial coating. Two-level antimicrobial coated membrane facilitated an increased water flux as the hydrophilicity of membrane increase. It reduced fouling and flux drop by natural water. The coating did not affect the separation ability which were then tested by dye rejection test.

Two-level antimicrobial coating was successfully adapted to microfiltration membrane. It was installed in point-of-use water filtration setup for field test. Field test was done and results proved the high antimicrobial ability of the coated membrane in real application. It can also lengthen the lifetime of microfiltration membrane in dead-end filtration.