title: Biomass characteristics of two types of submerged membrane bioreactors for nitrogen removal from wastewater.
abstract: Biomass characteristics and microbial community diversity between a submerged membrane bioreactor with mixed liquor recirculation (MLE/MBR) and a membrane bioreactor with the addition of integrated fixed biofilm medium (IFMBR) were compared for organic carbon and nitrogen removal from wastewater. The two bench-scale MBRs were continuously operated in parallel at a hydraulic retention time (HRT) of 24h and solids retention time (SRT) of 20d. Both MBRs demonstrated good COD removal efficiencies (>97.7%) at incremental inflow organic loading rates. The total nitrogen removal efficiencies were 67% for MLE/MBR and 41% for IFMBR. The recirculation of mixed liquor from aerobic zone to anoxic zone in the MLE/MBR resulted in higher microbial activities of heterotrophic (46.96mgO(2)/gVSSh) and autotrophic bacteria (30.37mgO(2)/gVSSh) in the MLE/MBR compared to those from IFMBR. Terminal Restriction Fragment Length Polymorphism analysis indicated that the higher nitrifying activities were correlated with more diversity of nitrifying bacterial populations in the MLE/MBR. Membrane fouling due to bacterial growth was evident in both the reactors. Even though the trans-membrane pressure and flux profiles of MLE/MBR and IFMBR were different, the patterns of total membrane resistance changes had no considerable difference under the same operating conditions. The results suggest that metabolic selection via alternating anoxic/aerobic processes has the potential of having higher bacterial activities and improved nutrient removal in MBR systems.
authors.affiliation: Department of Civil and Environmental Engineering, University of Missouri, E2509 Lafferre Hall, Columbia, MO 65211, USA.
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Liang
authors.forename: Atreyee
authors.initials: A
authors.lastname: Das
authors.forename: Daniel
authors.initials: D
authors.lastname: Beerman
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Hu
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D005374:Filtration; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D002244:Carbon; D009584:Nitrogen