Use of fluidised beds as turbulence promotors in tubular membrane systems

Abstract

INTRODUCTIOPS

Coupled effects of colloidal deposition and salt concentration polarization on reverse osmosis membrane performance

“…Large "fluidized particles" have been successfully applied in ultrafiltration with tubular membranes: mass transfer was shown to improve when 0.7 mm and smaller glass particles were used as turbulence promoters in ultrafiltration of polyethylene glycol [47] and when 3 mm stainless steel particles were used in the separation of gelatin solutions [48]. As our results indicate, colloid-sized particles can be used to achieve improvements in flux and rejection for salt rejecting membranes as well.…”

The Performance and Fouling Control of Submerged Hollow Fiber (HF) Systems: A Review

“…As early as the 1970s, the beneficial impact of the fluidization of particles for membrane processes was recognized as being attributable to both the mixing action of the particles to reduce the solute concentration gradient, and the mechanical action of the particles to both vibrate and clean the membrane surface [236][237][238][239]. These studies predate the submerged HF.…”

“…However, various types of inert solids subsequently have been shown to be beneficial for the mitigation of membrane fouling in submerged HF applications via the scouring mechanism [240][241][242][243][244], although negative effects such as the break-up of sludge flocs [240] and poor filterability of the activated sludge suspension [241] also have been noted. Another potential effect is membrane damage [238,242], which necessitates careful selection of scouring conditions. The use of powdered activated carbon (PAC) is primarily targeted for mitigating organic accumulation, biological degradation, and reducing the cake-resistance (e.g., [245][246][247][248][249][250][251][252][253]), all of which contribute towards improving the permeate flux.…”

“…A membrane autopsy performed by Zappia et al concluded that the unexpected presence of silicon dioxide spicules (needle-like structures) resulted in multiple membrane occlusions and punctures, leading to a loss in membrane integrity [321]. The erosive effect of fluidized particles [322][323][324][325] in the feed stream is also known to compromise the membrane integrity by impacting the membrane surface [123,238,242,[326][327][328][329]. Patterns of particle scraping was clearly observed [238,279], as well as a decrease in the membrane rejection for the larger fluidized glass beads (3 mm) [242].…”

Membrane assisted fluidized bed reactors: Potentials and hurdles

“…Use of a fluidized bed to promote turbulence in tubular membrane systems dates back to 1977 ( Van der Waal et al, 1977). The authors used a fluidized bed to suppress the concentration of polarization in tubular membrane modules for hyperfiltration and ultrafiltration processes.…”