Biofouling control based on bacterial quorum quenching with a new application: Rotary microbial carrier frame

Bacterial quorum quenching (QQ) is a new approach for controlling of membrane fouling in membrane bioreactors (MBRs). In this study, a novel bacterial immobilization medium named rotary microbial carrier frame (RMCF) was applied to inhibit biofilm formation in an MBR. RMCF was prepared by entrapping QQ bacteria (Rhodococcus sp. BH4) onto polycarbonate frame covered with microfiltration membrane. RMCF was submerged into the MBR using a rotational axle and rotated independently of the filtration module. QQ effect was examined with short- and long-term MBR operations. In MBRs operated with RMCF, transmembrane pressure (TMP) increasing rate was decreased with 65% efficiency. The prevention of biofouling resulted from both physical (shear forces) and biological (quorum quenching) effects of RMCF, and it was seen that RMCF could sustain its QQ effect over long-term operations. Biofilm formation inhibition by RMCF was confirmed visually using Confocal Laser Scanning Microscopy (CLSM). In addition, microbial population dynamics in MBRs were examined and it was found that RMCF had an effect on microbial diversity. The novelty of RMCF is to immobilize QQ bacteria into a rotating apparatus. With the application of RMCF, the anti-biofouling effect in an MBR had been investigated.