Characterization of the fouling layer on the membrane surface in a membrane bioreactor: Evolution of the foulants’ composition and aggregation ability

Linlin Yan, Ruixue Li, Yu Song, Yanping Jia, Zheng Li, Lianfa Song, Haifeng Zhang

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2 Scopus citations

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.

Original languageEnglish
Article number85
JournalMembranes
Volume9
Issue number7
DOIs
StatePublished - Jul 2019

Keywords

  • Aggregation
  • Extracellular polymeric substances
  • Membrane bioreactor
  • Membrane foulants
  • Transmembrane pressure

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