Fluid hydrodynamics in submerged and sidestream membrane bioreactors

Abstract

As with all membrane processes, turbulence, as promoted by aeration in submerged membrane bioreactors (MBRs) or pumping in sidestream (SS) systems to produce somewhat higher effective cross-flow velocities, increases mass transfer and reduces fouling. This is manifested in an elevated critical flux, the flux at which the membrane permeability is sustained. However, the non-Newtonian nature of the sludge makes precise rheological characterisation difficult. In this study, a calculation of the appropriate hydrodynamics parameters for a SS MBR configuration is presented. Optimisation of the aeration in a submerged MBR system has been attained by defining the minimum air velocity required for Taylor bubble formation.

Recent developments in forward osmosis membrane bioreactors: a comprehensive review

“…Comparing to the industrial standards for high-quality potable reuse applications (bioreactor, clarifier, microfiltration, RO, and advanced oxidation), FOMBR systems (bioreactor, FO, and DS reconcentration) have a better potential for producing high-quality water with fewer processes, reduced footprint [61]. As seen by all membrane processes, turbulence promoted by aeration in submerged MBRs or by pumping in sidestream systems results somewhat higher effective cross-flow velocities increasing the mass transfer and reducing the fouling [62]. Some comparative operational parameters in FOMBR and conventional MBR are presented in terms of energy consumption in Table 1.…”

Effect of bubble flow velocity on drag-force and shear stress working on submerged hollow fibre membrane

“…Laborie et al (1998) reported that slug flow of air and water inside a hollow fibre can maintain stable permeate flux. Le-Clech et al (2003) studied the optimization of aeration in a submerged MBR defining minimum air velocity requirement. Nagaoka et al (2001Nagaoka et al ( , 2003 measured directly shear stress on a wall in bubble flows and concluded that interaction between bubbles and a wall could induce strong shear stress on a wall and is an important factor for submerged MBRs using flat-sheet membranes to maintain stable flux.…”

Investigation of the effect of viscosity on slug flow in airlift tubular membranes in search of a sludge surrogate

“…In this type of MBR configuration, the sludge is pumped from the bioreactor to the membrane module and air is introduced at the base of the membranes to achieve a two-phase slug flow in the vertical tubes by an appropriate choice of sludge and air flow rates (Le-Clech et al 2003.…”