title: Comparison of sludge characteristics and PCR-DGGE based microbial diversity of nanofiltration and microfiltration membrane bioreactors.
abstract: The objective of this study was to compare the sludge characteristics and microbial community diversity between the submerged nanofiltration membrane bioreactor (NF MBR) and microfiltration membrane bioreactor (MF MBR) treating the same municipal wastewater. The influence of a higher concentration of organic matter and salt was investigated. The results of water qualities showed that the dissolved organic carbon (DOC), total phosphorus (T-P) and salt concentrations of the supernatant in the NF MBR were three, four and two times as high as those in the MF MBR, respectively. The specific oxygen uptake rate of the NF MBR (2.9+/-0.4 mg O(2)g(-1)MLSSh(-1)) was lower than that of the MF MBR (4.3+/-1.1 mg O(2)g(-1)MLSS h(-1)). Result of extractable extracellular polymeric substances showed that the NF MBR sludge had more protein and less polysaccharide compared to the MF MBR sludge, whereas specific amount of total organic carbon were the same in both MBRs. The median floc diameters of the NF MBR and the MF MBR were 72+/-12 microm and 59+/-12 microm, respectively, which could be attributable to the different polysaccharide concentrations between both MBR mixed liquor. A higher concentration of materials (DOC, T-P and salt) in the bioreactor, determined by the high rejection rate of the NF membrane, did not significantly affect the microbial diversity under similar operation conditions.
authors.affiliation: Department of Urban Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan. jaehoonchoi2@hanmail.net <jaehoonchoi2@hanmail.net>
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Choi
authors.forename: Sang Hyon
authors.initials: SH
authors.lastname: Lee
authors.forename: Kensuke
authors.initials: K
authors.lastname: Fukushi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D004275:DNA, Ribosomal / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005374:Filtration / Q000379:methods; D036103:Nanotechnology / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods; D012722:Sewage / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D004275:DNA, Ribosomal; D012722:Sewage