Novel aeration of a large‐scale flat sheet MBR: A CFD and experimental investigation

Abstract

Having previously established that the hydrodynamic effect introduced by slug bubbles is more effective and economic in fouling amelioration in flat sheet MBRs (FSMBR) than conventional bubbling, this work is focused on its implementation in a commercial FSMBR. The overall objective is to enhance the hydrodynamic effect on fouling control through the use of two‐stage large‐sized bubble development (coalescence and split). Computational Fluid Dynamics (CFD) was used to predict hydrodynamic features and substantial agreement was observed with experimental measurements. The critical height for bubble development space was determined to be circa 250 mm. Slug bubbles could be introduced into 14 channels, resulting in six‐fold stronger shear stress than that from single bubbles. Energy demand could be reduced by circa 50% compared with industry average usage and the shear stresses developed would, for most applications, be sufficient to ameliorate fouling. Furthermore, the specific air demand per permeate would be halved. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2721–2736, 2018

Computational fluid dynamics simulation as a tool for optimizing the hydrodynamic performance of membrane bioreactors

“…For example, PIV is widely used throughout the chemical industry for the study of ow eld distributions in stirred tank reactors, 24 at gas-evolving electrodes, 25 in bubble columns 26 and at sheet MBR. 27 For example, Liu et al 28 have used PIV to investigate the hydrodynamic characteristics of two-phase ow elds at gas-evolving electrodes, whilst Leslie et al 29 used PIV to determine the ow states in an aerated bench scale MBR.…”

Optimization of aeration variables in a commercial large-scale flat-sheet MBR operated with slug bubbling

“…Previous electrochemical experiments had showed that shear stress from over 60 mL slug bubble could produce excellent spanwise sheer stress of more than 1.0 Pa on the flat membrane [12]. Having established that the hydrodynamic effect introduced by slug bubbles is more effective and economic in fouling amelioration between two membranes in flat sheet MBRs (FSMBR) than conventional bubbling, our recent work has been focused on its implementation in a commercial-scale FSMBR [13,14], consisting of 100 membranes of the size normally used in industry. Recently a novel slug bubble production method has been developed through a two-stage process of bubble coalescence above the aerator followed by bubble splitting to 'feed' a number of channels [13].…”

“…Having established that the hydrodynamic effect introduced by slug bubbles is more effective and economic in fouling amelioration between two membranes in flat sheet MBRs (FSMBR) than conventional bubbling, our recent work has been focused on its implementation in a commercial-scale FSMBR [13,14], consisting of 100 membranes of the size normally used in industry. Recently a novel slug bubble production method has been developed through a two-stage process of bubble coalescence above the aerator followed by bubble splitting to 'feed' a number of channels [13]. This has proven to be fundamental to the implementation of slug bubbling hydrodynamics to large-scale FSMBRs [13].…”

“…Recently a novel slug bubble production method has been developed through a two-stage process of bubble coalescence above the aerator followed by bubble splitting to 'feed' a number of channels [13]. This has proven to be fundamental to the implementation of slug bubbling hydrodynamics to large-scale FSMBRs [13]. In our recent work it has been established that the combination of membrane plate thickness of 5mm and a channel gap of 6mm gave a uniform distribution of slug bubbles and high shear stress in all of the channels [14].…”

“…For FSMBR, Wei et al studied the slug bubbling between two membranes in various conditions by CFD simulation and image analyses [12]. Later Wang et al built a novel slug bubbling process through CFD simulation for a large-scale FSMBR with 100 membranes [13]. Subsequently an optimal condition of membrane plate thickness and channel gap was reported; again based on a combination of both CFD calculations and image analyses [14].…”