TY - JOUR
T1 - Impact of sludge retention time on the fine composition of the microbial community and extracellular polymeric substances in a membrane bioreactor
AU - Silva, Ana F.
AU - Antunes, Sílvia
AU - Saunders, Aaron
AU - Freitas, Maria Filomena Andrade de
AU - Vieira, Anabela
AU - Loureiro, Cláudia Filipa Reis Galinha
AU - Nielsen, Per H.
AU - Goulão Crespo, Maria Teresa Barreto
AU - Carvalho, Gilda
N1 - sem pdf conforme despacho.
Fundacao para a Ciencia e Tecnologia (UID/Multi/04462/2013 ; UCBIO-UID/Multi/04378/2013).
PY - 2016/10/1
Y1 - 2016/10/1
N2 - Membrane bioreactors (MBRs) are an advanced technology for wastewater treatment whose wide application has been hindered by rapid fouling of the membranes. MBRs can be operated with long sludge retention time (SRT), a crucial parameter impacting microbial selection in the reactor. This also affects filtration performance, since a major fouling agent are the extracellular polymeric substances (EPS). In this study, the impact of the SRT on the ecophysiology of the MBRs and, consequently, on membrane fouling was evaluated. A MBR was operated under a SRT of 60 days followed by a SRT of 20 days. A comprehensive analysis of the microbial community structure and EPS proteins and polysaccharide profiles of the mixed liquor and cake layer was carried out throughout both operation periods. The results of this study showed that the imposition of a shorter SRT led to a shift in the dominant bacterial populations. The mixed liquor and cake layer communities were very different, with Actinomycetales order standing out in the cake layer at SRT of 20 days. Overall, higher EPS concentrations (particularly proteins) were found at this SRT. Furthermore, EPS profiles were clearly affected by the SRT: it was possible to correlate a group of soluble EPS proteins with the SRT of 60 days, and a lower sludge age led to a lower diversity of polysaccharide sugar monomers, with an increase of glucose and galactose in the cake layer. This study improves our knowledge regarding the molecular reasons for fouling, which may contribute to improve MBR design and operation.
AB - Membrane bioreactors (MBRs) are an advanced technology for wastewater treatment whose wide application has been hindered by rapid fouling of the membranes. MBRs can be operated with long sludge retention time (SRT), a crucial parameter impacting microbial selection in the reactor. This also affects filtration performance, since a major fouling agent are the extracellular polymeric substances (EPS). In this study, the impact of the SRT on the ecophysiology of the MBRs and, consequently, on membrane fouling was evaluated. A MBR was operated under a SRT of 60 days followed by a SRT of 20 days. A comprehensive analysis of the microbial community structure and EPS proteins and polysaccharide profiles of the mixed liquor and cake layer was carried out throughout both operation periods. The results of this study showed that the imposition of a shorter SRT led to a shift in the dominant bacterial populations. The mixed liquor and cake layer communities were very different, with Actinomycetales order standing out in the cake layer at SRT of 20 days. Overall, higher EPS concentrations (particularly proteins) were found at this SRT. Furthermore, EPS profiles were clearly affected by the SRT: it was possible to correlate a group of soluble EPS proteins with the SRT of 60 days, and a lower sludge age led to a lower diversity of polysaccharide sugar monomers, with an increase of glucose and galactose in the cake layer. This study improves our knowledge regarding the molecular reasons for fouling, which may contribute to improve MBR design and operation.
KW - Extracellular polymeric substances
KW - Membrane bioreactor
KW - Microbial community
KW - Polysaccharide
KW - Protein
KW - Sludge retention time
UR - http://www.scopus.com/inward/record.url?scp=84986557051&partnerID=8YFLogxK
U2 - 10.1007/s00253-016-7617-2
DO - 10.1007/s00253-016-7617-2
M3 - Article
AN - SCOPUS:84986557051
SN - 0175-7598
VL - 100
SP - 8507
EP - 8521
JO - Applied Microbiology and Biotechnology
JF - Applied Microbiology and Biotechnology
IS - 19
ER -