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• A novel method of electrospinning was employed to enhance quorum quenching hydrogel. • QQ-ECHB performs excellent physical stability and environmental-tolerance. • Stable and long-lasting quorum quenching can be effected at low dosage of QQ-ECHB. • MBR biofouling greatly mitigated and extended service cycle with QQ media addition. Bacterial quorum quenching (QQ) is an effective strategy for controlling biofouling in membrane bioreactor (MBR) by interfering the releasing and degradation of signal molecules during quorum sensing (QS) process. However, due to the framework feature of QQ media, the maintenance of QQ activity and the restriction of mass transfer threshold, it has been difficult to design a more stable and better performing structure in a long period of time. In this research, electrospun fiber coated hydrogel QQ beads (QQ-ECHB) were fabricated by using electrospun nanofiber coated hydrogel to strengthen layers of QQ carriers for the first time. The robust porous PVDF 3D nanofiber membrane was coated on the surface of millimeter-scale QQ hydrogel beads. Biocompatible hydrogel entrapping quorum quenching bacteria (sp.BH4) was employed as the core of the QQ-ECHB. In MBR with the addition of QQ-ECHB, the time to reach transmembrane pressure (TMP) of 40 kPa was 4 times longer than conventional MBR. The robust coating and porous microstructure of QQ-ECHB contributed to keeping a lasting QQ activity and stable physical washing effect at a very low dosage (10g beads/5L MBR). Physical stability and environmental-tolerance tests also verified that the carrier can maintain the structural strength and keep the core bacteria stable when suffering long-term cyclic compression and great fluctuations in sewage quality. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The BH4 immobilized media were prepared using nano-silica and silica beads as core reinforcements. • The inclusion of two types of silicon in the beads ensured they were ready for prolonged use. • The application of two quorum quenching media effectively mitigated MBR biofouling. 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Double-layer gel beads were prepared to promote the synergistic effect of QQ bacteria and PAC. • The surface of the porous shell-with PAC layer was rough and uneven. • The core part QQ bacteria embedded was a dense sponge structure. • The addition of PAC into the shell can improve the mass transfer conditions and adsorption capacity. Quorum quenching (QQ) has been proven to be an effective method to reduce MBR membrane biological contamination. In this paper, a novel and efficient QQ-PAC core-shell beads were prepared for mitigating the membrane contamination. The bead was composed of two parts: QQ bacteria embedded in the core and PAC in the shell. The microstructure of the bead was observed by scanning electron microscopy (SEM) and the functional groups were revealed by Fourier transform infrared spectroscopy (FTIR). Meanwhile, the mechanical strength, swelling property, penetration property and QQ activity of the core bead, the core shell-without PAC bead and the core shell-with PAC bead were compared. The core shell-with PAC structure improved the adsorption capacity under good mass transfer conditions. Besides, the combined effect of QQ bacteria and PAC enhanced the QQ effect and alleviated the process of MBR membrane biological contamination consequently. Therefore, the QQ-PAC core-shell beads have a potential possibility in MBR membrane fouling control as the immobilization technology of QQ bacteria. [ABSTRACT FROM AUTHOR]