Silica reinforced core-shell quorum quenching beads to control biofouling in an MBR

Abstract

Quorum quenching (QQ) is a strategy to alleviate membrane biofouling in membrane bioreactors (MBRs). As a stable inorganic material with a large specific surface area, silica is often used to prepare of microbial immobilization composites. This study selected two different sizes of silica materials (silica beads and Nano-silica) to make the core encapsulate a QQ bacterial strain (Rhodococcus sp. BH4). The compressive strength and stability under extreme environments were characterized, and the positive effect of silica on QQ beads was verified. The results showed that both QQ beads could resist the impact of high pressure, acid, alkali, salt and EDTA buffer. It was proved that they have the potential to quench effectively continuously. Both beads were still more than 70 % QQ activity after five months of use. In the lab-scale continuous MBR experiment, the time of transmembrane pressure (TMP) reaching 50 kPa in both experimental groups was more than 3 times that in the blank group. The TMP contamination time was extended from 5 to 6 days in the blank group to 18–19 days. Among them, silica beads greatly improve the compressive strength of the beads, and also have a better performance in QQ.