Characterization of the Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Evolution of the Foulants’ Composition and Aggregation Ability

Abstract

In this study, the characteristics of membrane foulants were analyzed with regard to morphology, composition, and aggregation ability during the three stages of transmembrane pressure (TMP) development (fast–slow–fast rise in TMP) in a steady operational membrane bioreactor (MBR). The results obtained show that the fouling layer at the slow TMP-increase stage possessed a higher average roughness (71.27 nm) and increased fractal dimension (2.33), which resulted in a low membrane fouling rate (0.87 kPa/d). A higher extracellular DNA (eDNA) proportion (26.12%) in the extracellular polymeric substances (EPS) resulted in both higher zeta potential (-23.3 mV) and higher hydrophobicity (82.3%) for initial foulants, which induced and increased the protein proportion in the subsequent fouling layer (74.11%). Furthermore, the main composition of the EPS shifted from protein toward polysaccharide dominance in the final fouling layer. The aggregation test confirmed that eDNA was essential for foulant aggregation in the initial fouling layer, whereas ion interaction significantly affected foulant aggregation in the final fouling layer.

Coupling of Immobilized Photosynthetic Bacteria with a Graphene Oxides/PSF Composite Membrane for Textile Wastewater Treatment: Biodegradation Performance and Membrane Anti-Fouling Behavior

“…Moreover, it was demonstrated that large numbers of PSB cells were immobilized into porous macrospheres, which could be beneficial to enhancing the performance of the MBR in treating wastewater. It was noted that the filtration capacity of the membrane was closely related to the characteristics of sludge flocs in the bioreactor [ 44 , 45 ]. Therefore, in order to understand what influences immobilized photosynthetic bacteria in terms of membrane fouling, the various characteristics of the immobilized microorganism were investigated in detail.…”

Recent Advances in Superhydrophobic and Antibacterial Cellulose-Based Fibers and Fabrics: Bio-inspiration, Strategies, and Applications

“…5c). It was found that these disordered nanostructures on the dragonfly wing were more effective in reducing protein adhesion than the ordered cicada replicated surface, thus the dragonfly wing surface was highly effective in inhibiting the adhesion of bacteria (i.e., Gram-negative and -positive) due to the disruption of cell surface in contact with the nanostructures [80][81][82][83]. Figure 5d shows the four stages of E. coli death process, respectively.…”

Characterization of the Initial Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Effects of Permeation Drag

“…However, membrane fouling, especially biofouling, has been the main obstacle for the wide application of MBRs [3]. It is widely known that biofouling starts with the deposition of foulants during the initial stages of membrane filtration, resulting in the development of additional fouling layers on the membrane surface [4]. The initial fouling layer affects the intrinsic properties of the membrane and thereby the subsequent development of additional layers [5].…”