Effect of Aeration Intensity on Performance of Lab-Scale Quorum-Quenching Membrane Bioreactor

Abstract

Biofouling is one of the main drawbacks of membrane bioreactors (MBRs). Among the different methods, the quorum-quenching (QQ) technique is a novel method as it delays biofilm formation on the membrane surface through disruption of bacterial cell-to-cell communication and thus effectively mitigates membrane biofouling. QQ bacteria require a certain concentration of dissolved oxygen to show their best activities. Despite the importance of the amount of aeration, there have not been enough studies on aeration condition utilizing the separate determination of pure QQ effect and physical cleaning effect. This research aimed to find the optimum aeration intensity by separation of the two effects from QQ and physical cleaning. Three bead type conditions (no bead, vacant bead, and QQ beads) at three aeration intensities (1.5, 2.5, and 3.5 L/min representing low, medium, and high aeration intensity) were applied. From the results, no QQ effect and small QQ effect were observed at low and high aeration, while the greatest QQ effect (48.2% of 737 h improvement) was observed at medium aeration. The best performance was observed at high aeration with QQ beads having a 1536 h operational duration (303% improvement compared to the no bead condition); however, this excellent performance was attributed more to the physical cleaning effect than to the QQ effect.

Preparation and Characterization of Novel Polyvinyl Alcohol-Alginate Beads for Quorum Quenching Application in Membrane Bioreactors

“…where the polymer mixture is composed of a 10:1 ratio of PVA and SA. Nevertheless, Islam et al [12] took a slightly different approach, forming beads with 8% w/v PVA and 1% w/v SA, utilizing PVA with a degree of polymerization close to that reported by Lee. Despite existing research on the fabrication of PVA-ALG beads, a study to date has yet to explore the effect of change in PVA and SA composition, mainly the concentration of PVA, in relation with the structural, textural properties and AHL incorporation capacity of beads.…”

“…The frequent collision of mobile QQ-medias with the ltration membrane enhances bio lm detachment in conjunction with AHL degradation by QQ-bacteria [11]. Of all the mentioned mobile QQ media, QQ-beads are common due to their relative ease of preparation compared to hollow cylinders and sheets [12]. Hydrogel-based QQ bacteria cell entrapping beads (CEBs) composed of only Sodium Alginate (SA) were rst introduced by Kim et al [4].…”

“…Chemical crosslinking of PVA and SA by using boric acid (H 3 BO 3 ) and calcium chloride (CaCl 2 ) is the most common, easy, and cost-effective method to produce durable beads [12]. QQ-beads formed using only boric acid and calcium chloride crosslinking agents are not suitable for direct use in MBRs due to the reversible nature of the boric acid-PVA complex upon immersion in water, as reported by Zain et al [15].…”

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

“…Biofouling reduces membrane permeability and increases the number of chemical cleaning and membrane replacement, leading to an increase in the operating costs of MBR processes and potential impacts on the environment due to disposal of used chemicals. [1][2][3] Through quorum sensing (QS), which is densitydependent cellular signaling, microorganisms can form biofilms. Cells secrete and sense signaling molecules (e.g., N-acyl homoserine lactones or AHLs) to detect their population density.…”

“…Biofouling reduces membrane permeability and increases the number of chemical cleaning and membrane replacement, leading to an increase in the operating costs of MBR processes and potential impacts on the environment due to disposal of used chemicals. 1–3…”