TY - JOUR
T1 - Characterization of the fouling layer on the membrane surface in a membrane bioreactor
T2 - Evolution of the foulants’ composition and aggregation ability
AU - Yan, Linlin
AU - Li, Ruixue
AU - Song, Yu
AU - Jia, Yanping
AU - Li, Zheng
AU - Song, Lianfa
AU - Zhang, Haifeng
N1 - Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2019/7
Y1 - 2019/7
N2 - 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.
AB - 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.
KW - Aggregation
KW - Extracellular polymeric substances
KW - Membrane bioreactor
KW - Membrane foulants
KW - Transmembrane pressure
UR - http://www.scopus.com/inward/record.url?scp=85070746763&partnerID=8YFLogxK
U2 - 10.3390/membranes9070085
DO - 10.3390/membranes9070085
M3 - Article
AN - SCOPUS:85070746763
SN - 2077-0375
VL - 9
JO - Membranes
JF - Membranes
IS - 7
M1 - 85
ER -