Micro-patterned membranes with enzymatic quorum quenching activity to control biofouling in an MBR for wastewater treatment

In this study, a patterned quorum quenching (QQ) membrane with anti-biofouling characteristics was prepared via a patterning process of an oxidized multiwall carbon nanotube (o-MWCNT) composite membrane followed by immobilization of QQ enzymes. We verified that the o-MWCNTs with a high specific surface area helped the patterned membrane retain 32% more enzyme compared to the case without the o-MWCNTs. Furthermore, the micro-pattern on the membrane surface increased the effective membrane area (similar to 1.6 times), offsetting the membrane resistance additionally caused by enzyme immobilization. The patterned QQ membrane kept the relative activity at above 40% of the initial activity for 39 days due to the cross-linking. It was also confirmed in a flow cell test that the patterned QQ membrane had much more control over biofilm formation by effectively disrupting quorum sensing compared to the patterned membrane. Due to the combined effect of the QQ activity and the pattern effect (e.g., low permeation drag), the patterned QQ membrane (2.2 times) significantly lengthened the time between chemical cleanings compared to the non-patterned membrane. The combined effect also reduced the specific filtration energy consumption of the patterned QQ membrane to less than half of that of the non-patterned membrane as the two membranes were used to produce the same amount of the treated water during the same period. We expect that the patterned QQ membrane will open and facilitate interdisciplinary research combining patterned membranes with technologies in other areas to improve the antifouling properties of patterned membranes.