TY - JOUR
T1 - Membrane biofouling in a wastewater nitrification reactor
T2 - Microbial succession from autotrophic colonization to heterotrophic domination
AU - Lu, Huijie
AU - Xue, Zheng
AU - Saikaly, Pascal
AU - Nunes, Suzana P.
AU - Bluver, Ted R.
AU - Liu, Wen Tso
N1 - This study was funded by King Abdullah University of Science and Technology under Award Number: 65317 (KAUST, Thuwal, Saudi Arabia). We would like to thank Chris Wright at the Roy J. Carver Biotechnology Center for performing Illumina Miseq sequencing. We also thank Dr. Husnul Maab and Pradeep Neelakanda at KAUST Biological and Environmental Science and Engineering Division for their assistance in membrane preparation.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles.
AB - Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles.
KW - Bacterial succession
KW - Biofilm structure
KW - Biofouling
KW - Nitrification
KW - Submerged MBR
UR - https://www.scopus.com/pages/publications/84945980744
UR - https://www.scopus.com/pages/publications/84945980744#tab=citedBy
U2 - 10.1016/j.watres.2015.10.013
DO - 10.1016/j.watres.2015.10.013
M3 - Article
C2 - 26512812
AN - SCOPUS:84945980744
SN - 0043-1354
VL - 88
SP - 337
EP - 345
JO - Water Research
JF - Water Research
ER -