Porous shell quorum quenching balls for enhanced anti-biofouling efficacy and media durability in membrane bioreactors

Microbial quorum quenching (QQ) has been recognized as an effective anti-biofouling strategy for membrane bioreactors (MBRs), but long-term hydrogel QQ media durability is uncertain. In this study, we propose a new media design to enhance anti-biofouling efficacy and mechanical media stability. Mobile porous hard-shell balls to hold QQ sheets (named QQ balls) were found to be superior in QQ stability to both fixed and freely moving QQ sheets. Fouling mitigation by QQ balls was significant even at the lowest aeration intensity tested (51 s(-1)), in contrast to other QQ media. QQ balls saved substantive energy (similar to 50%) at similar or lower fouling rates (2.8-3.2 kPa/d) compared to the others tested at the higher aeration intensity (72 s(-1)). QQ balls maintained their initial high level of QQ activity (similar to 3.0 h(-1)) during long-term use (greater than160 d), whereas other types of QQ media did not (< 1.3 h(-1)). The mechanical strength of free QQ media significantly deteriorated over time (similar to 87-100% losses after 160-d use), but QQ balls prevented the active media from such damage. QQ media had no impacts on treatment efficiencies. A QQ media structure comprising a hard porous shell and inner active media encapsulating QQ bacteria is a promising QQ media architecture for sustainable MBR applications.

Automated summary

The new design of QQ balls showed superior stability in quorum quenching, significantly reduced biofouling, saved energy, maintained high QQ activity during long-term use, and proved to be a promising structure for sustainable MBR applications.