Novel economical three‐stage slug bubbling process in a large‐scale flat‐sheet membrane bioreactor of double deck configuration

Abstract

Slug bubbling in single deck flat sheet membrane bioreactor (FSMBR) is effective in controlling membrane fouling. Here the primary focus is on the employment of the slug bubbling method, with its more economical air consumption, to a double‐deck large‐scale FSMBR with 100 membrane plates on each deck. The analysis of a new design concept shows that sufficient hydrodynamic effect could be induced by a novel economical three‐stage slug aeration process of formation‐breakup‐reformation. Computational fluid dynamics simulation was applied to examine both the development of the slug bubble and especially its reformation. It was found that the combination of a gap between two decks of 400 mm with an air velocity of 16 m/s was an optimal condition to achieve good hydrodynamic conditions in both decks. The corresponding SADm is 0.098 Nm3m−2 hr−1, which is a reduction of 66% compared to the most advanced single deck FSMBR.

Wastewater treatment in large-scale novel corrugated-sheet MBR

“…After determining the optimal aeration pipe design, the variation of gap distance between the bottom two decks (ground decks) and the top two decks (top decks) of a CS-MBR was studied. In one of our previous studies, it is shown that slug bubble could induce effective hydrodynamics for a FS membrane height of 1500 mm [30]. Now considering that the CS membrane height is 725 mm, the ground two decks in a CS-MBR were arranged together with no gap distance (h1), and the same was done for the upper two decks, i.e.…”

“…Thus the distance h2 between the middle two decks (i.e., space between the second and third deck in Fig. S3) was the key variable because the processes of bubble recombination and redistribution into the upper layer of membrane modules is strongly influenced by the height of this region [30]. The distance h2 was varied from 100 to 600 mm, with nozzle air velocity fixed at 13 m/s.…”

“…Issues addressed in our study included the aeration system and the spacing between decks. The spacing is known to influence the two-phase flow in the upper part [30]. Moreover, although there is a link between the hydrodynamics and fouling [31][32][33][34], it is important to assess if the new design created unexpected dead-zones which might cause unexpected fouling.…”

Aeration pipe design for free bubbling hydrodynamic optimization of flat sheet MBRs

“…More recently within our group, Wang and coworkers proposed, and studied through CFD and experimental methods, an intermittent bubbling process with large-coalescence bubbles [22][23][24][25]. In addition to this work on slug bubbling they have also proposed new aeration designs for free bubbling process [26] and this is also the subject addressed herein.…”

Innovation and optimization of aeration in free bubbling flat sheet MBRs

“…With the increase of the number of super large MBR (≥100,000 m 3 /d), the two decks FSMBR system, which has a higher capacity of water treatment is the focus in industry. Hence, three-stage intermittent bubbling process (bubble coalescence-split-reunion) in a double-deck FSMBR configuration was studied therein to provide sufficient shear stress onto all membranes whilst economically decreasing the air consumption [30]. The process has been applied commercially by Oxiamembrane Co. Ltd (http://www.oxiamem.com).…”