Recently, spherical beads entrapping quorum quenching (QQ) bacteria have been reported as effective moving QQ-media for biofouling control in MBRs for wastewater treatment owing to their combined effects of biological (i.e., quorum quenching) and physical washing. Taking into account both the mass t...
Recently, spherical beads entrapping quorum quenching (QQ) bacteria have been reported as effective moving QQ-media for biofouling control in MBRs for wastewater treatment owing to their combined effects of biological (i.e., quorum quenching) and physical washing. Taking into account both the mass transfer of signal molecules through the QQ-medium and collision efficiencies of the QQ-medium against the filtration membranes in a bioreactor, a cylindrical medium (QQ-cylinder) was developed as a new shape of moving QQ-medium. The QQ-cylinders were compared with previous QQ-beads in terms of the QQ activity and the physical washing effect under identical loading volumes of each medium in batch tests. It was found that the QQ activity of a QQ-medium was highly dependent on its specific surface area, regardless of the shape of the medium. In contrast, the physical washing effect of a QQ-medium was greatly affected by its geometric structure. The enhanced anti-biofouling property of the QQ-cylinders relative to QQ-beads was confirmed in a continuous laboratory-scale MBR with a flat-sheet membrane module.
Recently, spherical beads entrapping quorum quenching (QQ) bacteria have been reported as effective moving QQ-media for biofouling control in MBRs for wastewater treatment owing to their combined effects of biological (i.e., quorum quenching) and physical washing. Taking into account both the mass transfer of signal molecules through the QQ-medium and collision efficiencies of the QQ-medium against the filtration membranes in a bioreactor, a cylindrical medium (QQ-cylinder) was developed as a new shape of moving QQ-medium. The QQ-cylinders were compared with previous QQ-beads in terms of the QQ activity and the physical washing effect under identical loading volumes of each medium in batch tests. It was found that the QQ activity of a QQ-medium was highly dependent on its specific surface area, regardless of the shape of the medium. In contrast, the physical washing effect of a QQ-medium was greatly affected by its geometric structure. The enhanced anti-biofouling property of the QQ-cylinders relative to QQ-beads was confirmed in a continuous laboratory-scale MBR with a flat-sheet membrane module.
The anti-biofouling capability of the QQ-cylinders was also evaluated in a continuous laboratory-scale MBR with a flat-sheet membrane module. Based on those results, the effects of shape and size on the performance of the QQ-medium were investigated to determine the dominant parameters affecting its performance in QQ-MBRs.
Three sizes of QQ-beads (diameter: 3.1-5.6 mm) and four sizes of QQ-cylinders (diameter: 1.3-5.2 mm; length: 4.7-75.4 cm) were prepared to investigate the effect of the shape and size of the media on QQ activity. Having a total volume of QQ-media fixed at 1 ml (i.
이론/모형
Mixed liquor suspended solids (MLSS) and chemical oxygen demand (COD) were measured according to standard methods [10].
성능/효과
In Fig. 5, the physical washing effect of bead B, with a smaller diameter (3.1mm ) but higher number (N = 355), was approximately 30% greater than that of bead A, with a larger diameter (4.3 mm) but lower number (N = 1 31). However, when the shape was changed from bead to cylinder (diameter: 1.
9D). As demonstrated in batch studies, the improved inhibition of biofouling in the QQ-cylinder MBR may be attributed to the higher QQ activity and physical washing effect of the QQ-cylinders compared with QQ-beads.
Based on the contradictory results from observing the two different cylinders, it had been concluded that the presence of BH4 (QQ bacteria) limits the diffusion of signal molecules toward the center of the medium because most AHLs were degraded by the BH4 located near the surface of the medium. Consequently, QQ bacteria at the inner part of a medium may be deprived of opportunities to encounter and decompose signal molecules.
5. Because the physical washing effect was the same with vacant-cylinders and QQ-cylinders, the delay of TMP rise-up in the QQ-cylinder MBR could be attributed to the biological QQ activity of the QQ-cylinders. In phase 3, the vacant-cylinder MBR was compared with the vacant-bead MBR (Fig.
In summary, substances attached to the PC plate could be expected to be detached, at least partly, by collisions between the PC plate and the media. Consequently, the QQ-cylinders are expected to have a greater physical washing effect than the QQ-beads owing to their higher contact frequency.
5, indicating that the rate of TMP rise-up in the vacant-cylinder MBR was delayed approximately 150% longer than that in the vacant-bead MBR. Consequently, the better physical washing effect of the cylinders compared with the beads was confirmed in continuous MBR.
In this study, the effects of the shape and size of QQ-medium on QQ activity and physical washing effect were separately investigated in different batch tests. However, there might be a synergistic effect between the QQ activity and the physical washing, in that the efficiency of QQ activity would be improved owing to detachment of the biofilm by physical washing.
The QQ activities and physical washing effect of beads and cylinders of different sizes were compared in batch tests. It was found that the QQ activity of the QQ-medium was highly dependent on its total surface area regardless of the medium shape. In contrast, the physical washing effect of the media was greatly affected by the medium shape.
the aspect ratio. It was found that the physical washing effect of the cylinders tended to show a positive relationship with the aspect ratio (Fig. S2).
5% (v/v)), cylinders with identical diameters but different lengths and numbers were compared with each other in terms of their physical washing effect. The physical washing effect of the cylinders increased with the increase in their length, despite a decrease in number (Fig. 8A), indicating that the length of the cylinder is more important than the number in terms of the physical washing effect.
8 l/min. The ratio of TTMP value of the QQ-cylinder MBR to that of the QQ-bead MBR was calculated to be 1.6, which indicates that the TMP rise-up of the QQ-cylinder MBR was delayed more by about 60% compared with that of the QQ-bead MBR (Fig. 9D).
S1. This indicates that the net QQ activity of the QQ-media, excluding the physical washing effect, was not dependent on the shape of the media (bead or cylinder) under the identical loading volume of QQ-media. However, the total surface area was found to be important for the biological QQ activity under identical loading volume.
3). Under an identical loading volume of QQ-media (1 ml), the QQ activities of the beads increased as the number of beads increased, but their diameters decreased. In contrast, the QQ activities of the cylinders increased as their diameters decreased, but their lengths increased even though the number of cylinders was the same (i.
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