Innovative Biofouling Control for Membrane Bioreactors in Cold Regions by Inducing Environmental Adaptation in Quorum-Quenching Bacteria

Abstract

Bacterial quorum quenching (QQ), whose mechanism involves the degradation of quorum-sensing signal molecules, is an effective strategy for controlling biofouling in membrane bioreactors (MBRs). However, MBRs operated at low temperatures, either due to cold climates or seasonal variations, exhibit severe deterioration in QQ efficiency. In this study, a modified culture method for Rhodococcus sp. BH4, a QQ bacterium, was developed to induce environmental adaptation in cold regions. BH4-L, which was prepared by the modified culture method, showed enhancement in QQ efficiency at low temperatures. The higher QQ efficiency obtained by employing BH4-L at 10 °C (compared with that obtained by employing BH4 at 10 °C) was attributed to the higher live/dead cell ratio in the BH4-L-entrapping beads. When BH4-L-entrapping beads were applied to lab-scale MBRs operated at low temperatures, membrane biofouling in MBRs at low temperatures was successfully mitigated because BH4-L could substantially reduce the concentration of signal molecules (N-acyl homoserine lactones) in the biocake. Employing BH4-L in QQ-MBRs could offer a novel solution to the problem of severe membrane biofouling in MBRs in cold regions.

Application of psychrotolerant quorum quenching Planococcus versutus sp. L10.15T to membrane bioreactors for biofouling control at low temperatures

“…The solution was used to prepare the polymeric beads, as described previously. 22 In this study, beads entrapping L10.15 T and BH4 were named L10.15 T -beads and BH4-beads, respectively. Polymeric beads with no bacteria (named NB-beads) were also prepared using DI water instead of QQ bacterial resuspension.…”

“…Specifically, the polysaccharide concentration in the biocake was 24.5 (±1.67) mg g −1 for the L10.15 T -MBR, corresponding to 42.6% reduction in comparison In some previous studies, the concentration of polysaccharides decreased more greatly than that of proteins, which is similar to the results of this study. 20,22 However, the degree of reduction in polysaccharide and protein concentrations varied.…”

“…These results are consistent with those of several previous studies. 22,36,37 Therefore, the greater anti-biofouling efficiency of L10.15 T -beads is attributed mainly to the more effective reduction in the polysaccharide content resulting from its higher QQ activity than that of BH4 at 10 °C.…”

“…10 To overcome the reduction in QQ efficiency at low temperatures, Min et al developed a modified culture method including low-temperature subcultivation for the adaptation of BH4 to low temperatures and reported that BH4 cultivated by the method mitigated biofouling of MBRs at low temperatures. 22 Alternatively, a viable option is to introduce psychrotolerant bacteria naturally possessing QQ activity at low temperatures into MBRs operated in cold climates, a method yet unexplored.…”

Maintaining Antibacterial Activity against Biofouling Using a Quaternary Ammonium Membrane Coupling with Electrorepulsion

“…Biofouling is a significant challenge for membrane filtration, which deteriorates water quality and increases energy consumption, particularly after long-term operation. 1,2 The formation of a biofouling layer and the subsequent production of biopolymers can cause severe membrane fouling, 3,4 irrespective of the treatment of drinking water, domestic wastewater, or industrial wastewater. The inactivation technology (e.g., oxidation, contact biocide, and electroporation) is an advantageous alternative to prevent the adhesion and growth of bacteria on the membrane surface.…”