Abstract
In membrane bioreactors (MBRs), N-acyl homoserine lactones
(AHLs)-related quorum sensing (QS) has been described as one of the main
causes of biofouling during wastewater treatment. Quorum-quenching (QQ)
bacteria for the mitigation of QS in MBRs have been applied but limited
to entrapping methods only. Thus, this study investigates the direct
injection of different doses (0–77.2 mg/d) of unentrapped QQ strains (Rhodococcus sp.
BH4) into a probiotic QQ MBR (i.e., bioaugmented reactor) while
monitoring the changes in fouling rates as well as microbial
communities, biopolymers, signal molecules, and treatment performances.
The QQ bacteria show effective biofouling mitigation in diverse MBR
phases, but a halt in QQ bacteria injection leads to increased fouling
rates in the probiotic QQ MBR. The QQ bacteria exhibit a noticeable AHL
degradation rate during BH4 inoculation as opposed to when inoculation
is halted. They also have significant inhibitory effects on the
generation of soluble carbohydrates and proteins. However, cell-bound
extracellular polymeric substance (EPS) concentrations are relatively
higher in the probiotic QQ reactor despite decreased fouling rates. This
can be ascribed to the production of EPS by injected BH4, as revealed
in pure BH4 batch cultures. Probiotic QQ has impacts on both the
relative bacterial abundance and the overall microbial composition. Thiothrix
is identified as the most dominant genus in the mixed liquor of both
MBRs; however, its relative abundance becomes low in the probiotic MBR
during QQ bacteria injection. These findings provide valuable
information that will foster the development of improved QQ strategies
in MBRs.
Original language | English |
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Article number | 135572 |
Journal | Chemical Engineering Journal |
Volume | 438 |
Number of pages | 12 |
ISSN | 1385-8947 |
DOIs | |
Publication status | Published - 2022 |
Keywords
- Membrane biofouling
- Microbial community
- Rhodococcus sp. BH4
- Quorum quenching
- Quorum sensing