title: Biological nitrogen and phosphorus removal and changes in microbial community structure in a membrane bioreactor: effect of different carbon sources.
abstract: Bacterial community structures in four sequencing anoxic/anaerobic-aerobic membrane bioreactors (SAMs) that were fed with synthetic medium composed of different organic compounds in substrate as carbon source; acetate-dominant (acetate/propionate = 4/1), propionate-dominant (acetate/propionate = 1/4), glucose-dominant (glucose/acetate = 4/1) and methanol-dominant (methanol/acetate/propionate = 6/3/1) were analyzed by respiratory quinone profile and fluorescent in situ hybridization (FISH) techniques. The SAMs were operated at controlled pH range 7-8.5 and at constant temperature 25 degrees C. Total nitrogen (TN), total phosphorus (TP) and COD removal performances were also evaluated and compared. In addition, trans-membrane pressure was monitored to observe the impact of substrate composition on membrane fouling. The dominance of the mole fraction of ubiquinone (UQ-8) in the SAMs indicated dominance of the beta-subclass of Proteobacteria; however, its population comparatively decreased when the substrate was glucose dominant or methanol dominant. A relatively higher and stable enhanced biological phosphorus removal performance was observed when methanol-dominant substrate was used concurrently with an increase in the gamma-subclass of Proteobacteria. The population of the alpha-subclass of Proteobacteria slightly increased along with a decrease in phosphate removal activity when the substrate was glucose-dominant. Results from FISH analysis also supported the findings of the quinone profile. The trans-membrane pressure variation in the SAMs indicated that fouling was relatively rapid when propionate-dominant or methanol-dominant substrate was used and most stable when glucose-dominant substrate was used. A combination of methanol and acetate would be a better choice as an external carbon source when nutrients removals, as well as fouling, are considered in the membrane bioreactor- (MBR-) coupled biological nutrients removing (BNR) process.
authors.affiliation: Center for Environmental Technology Research, Energy & Environment Research Division, Korea Institute of Science and Technology, Seoul 130-650, Republic of Korea. ahmed@kist.re.kr
authors.forename: Zubair
authors.initials: Z
authors.lastname: Ahmed
authors.forename: Byung-Ran
authors.initials: BR
authors.lastname: Lim
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Cho
authors.forename: Kyung-Guen
authors.initials: KG
authors.lastname: Song
authors.forename: Ki-Pal
authors.initials: KP
authors.lastname: Kim
authors.forename: Kyu-Hong
authors.initials: KH
authors.lastname: Ahn
mesh_terms: D000085:Acetates / Q000378:metabolism; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D000432:Methanol / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D011809:Quinones / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D000085:Acetates; D011809:Quinones; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen; D000432:Methanol