Membrane fouling caused by sub-micron particles in a mixed liquor suspension of an MBR

Abstract

Membrane fouling needs to be mitigated for widespread use of membrane bioreactors (MBRs). It has been pointed out that particles with small sizes found in supernatants (sub-micron particles) of mixed liquor suspensions of MBRs are important in the evolution of membrane fouling of this technology. However, information on characteristics of sub-micron particles in MBRs is still insufficient. In this study, a pilot-scale MBR treating municipal wastewater was used to investigate and characterize sub-micron particles in an MBR and to identify the size fraction(s) responsible for irreversible fouling in an MBR. It was clearly shown that characteristics of sub-micron particles in the MBR varied considerably depending on their sizes. Results of Fourier transform infrared (FTIR) analysis and monosaccharide analysis suggested that irreversible fouling in this study was mainly caused by the specific size fraction of 0.1-0.45 μm, which was close to the size of micropores of the membrane used. Pore plugging might explain this to some extent.

Characterization and Significance of Sub-Visible Particles and Colloids in a Submerged Anaerobic Membrane Bioreactor (SAnMBR)

“…It is expected that the particles and colloids in the subvisible range could contain a large amount of bacterial cells and cell debris, especially in bioreactor systems . However, the few studies examining particles and colloids in MBR systems focused mainly on the organic analysis (i.e., composition and functional groups), and rarely considered their microbiological and morphological composition. , The bacteria in these subvisible particles and colloids could potentially be pioneer species that attach to membranes to alter the formation of the fouling layer/biofilm, and hence there is a need to study the presence and distribution of bacterial cells in/on the subvisible particles and colloids in AnMBRs. This type of research is important for understanding membrane fouling in AnMBRs, and may lead to better strategies to control fouling.…”

Biological treatment and thickening with a hollow fibre membrane bioreactor

“…3000 mg L -1 NaOCl did not significantly recover the membrane permeability over an extended term. This is assumed to be indicative of irreversible pore plugging (Kimura et al, 2013;Shen et al, 2010).…”