title: Effect of dissolved oxygen concentration on the bioflocculation process in high loaded MBRs.
abstract: High-loaded membrane bioreactors (HL-MBRs), i.e. MBRs which are operated at extremely short sludge and hydraulic retention times, can be applied to flocculate and concentrate sewage organic matter. The concentrated organics can be used for energy recovery, or for the production of more valuable organic chemicals. Little is known about the effect of the dissolved oxygen concentration (DO) on this bioflocculation process. To examine this effect, two HL-MBRs were operated, respectively at a low (1 mg L(-1)) and a higher (4 mg L(-1)) DO. The higher DO resulted in a better flocculation efficiency, i.e. 92% of the colloidal COD in the sewage flocculated compared to 69% at the lower DO. The difference was attributed to a higher microbial production of extracellular polymeric substances at a DO of 4 mg L(-1) and to more multivalent cations (calcium, iron and aluminium) being distributed to the floc matrix. In addition, the HL-MBR that was operated at a DO of 4 mg L(-1) gave a bigger mean floc size, a lower supernatant turbidity, better settleability and better membrane filterability than the HL-MBR that was operated at a DO of 1 mg L(-1).
authors.affiliation: Wetsus-Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands; Sub-department of Environmental Technology, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands. Electronic address: lena.faust1@gmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Faust
authors.affiliation: Wetsus-Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands; Sub-department of Environmental Technology, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Temmink
authors.affiliation: Wetsus-Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Zwijnenburg
authors.affiliation: Membrane Science & Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: A J B
authors.initials: AJB
authors.lastname: Kemperman
authors.affiliation: Sub-department of Environmental Technology, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: H H M
authors.initials: HHM
authors.lastname: Rijnaarts
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D008567:Membranes, Artificial; D010100:Oxygen / Q000378:metabolism*
chemical_list: D008567:Membranes, Artificial; D010100:Oxygen
keywords: Bioflocculation; Dissolved oxygen; Extracellular polymeric substances; Membrane bioreactor