Effect of Oxygen Partial Pressure and Chemical Oxygen Demand Loading on the Biofilm Properties in Membrane-Aerated Bioreactors

Membrane-aerated biofilms with oxygen and nutrients diffusing from the opposite sides possess distinct properties, including the ability to couple aerobic and anaerobic processes. The objective of this study was to examine the effects of oxygen partial pressure and chemical oxygen demand (COD) loadi...

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Bibliographic Details
Published in:Water environment research 2009-03, Vol.81 (3), p.289-297
Main Authors: Zhu, I. X., Allen, D. G., Liss, S. N.
Format: Article
Language:English
Subjects:
Activated sludge
Air
Air - analysis
Applied sciences
Bacteria
biofilm structure
Biofilms
Biological and medical sciences
Biomass
Biotechnology
Chemical engineering
Chemical oxygen demand
confocal laser scanning microscopy
Exact sciences and technology
extracellular polymeric substances
Fundamental and applied biological sciences. Psychology
Hydrophobicity
membrane aerated bioreactor
Methods. Procedures. Technologies
Microbiology
nitrification
Others
Oxygen
Oxygen - chemistry
Oxygen partial pressure
P branes
Pollution
Porosity
Reactors
surface property
Various methods and equipments
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Summary:Membrane-aerated biofilms with oxygen and nutrients diffusing from the opposite sides possess distinct properties, including the ability to couple aerobic and anaerobic processes. The objective of this study was to examine the effects of oxygen partial pressure and chemical oxygen demand (COD) loading on biofilm properties. Two laboratory-scale membrane-aerated bioreactors were operated for a total of 283 days, with one reactor operated at 42, 60, and 89 kPa (0.41, 0.59, and 0.88 atm) oxygen, and the other reactor at 25 kPa (0.25 atm) oxygen (air control). The biofilm detached at the oxygen partial pressures of 60 and 89 kPa (0.59 and 0.88 atm) at a COD loading of 11.3 kg COD/1000 m²/d, but was sustained at the oxygen partial pressures of 25 and 42 kPa (0.25 and 0.41 atm), with a porous structure at the membrane interface at the COD loading of 11.3 kg COD/1000 m²/d. Biofilm formation was improved at a higher COD loading. It is proposed that the loss of extracellular polymeric substances at the biofilm bottom is the cause for the biofilm detachment subjected to a higher oxygen partial pressure.
ISSN:1061-4303
1554-7531
DOI:10.2175/106143008X325647