title: Diffusivity of oxygen in aerobic granules.
abstract: This work for the first time estimated apparent oxygen diffusivity (D(app)) of two types of aerobic granules, acetate-fed and phenol-fed, by probing the dissolved oxygen (DO) level at the granule center with a sudden change in the DO of the bulk liquid. With a high enough flow velocity across the granule to minimize the effects of external mass transfer resistance, the diffusivity coefficients of the two types of granules were estimated with reference to a one-dimensional diffusion model. The carbon source has a considerable effect on the granule diameter (d) and the oxygen diffusivity. The diffusivity coefficients were noted 1.24-2.28 x 10(-9) m2/s of 1.28-2.50 mm acetate-fed granules, and 2.50-7.65 x 10(-10) m2/s of 0.42-0.78 mm phenol-fed granules. Oxygen diffusivity declined with decreasing granule diameter, in particular, the diffusivity of acetate-fed granules is proportional to the size, whereas the diffusivity of phenol-fed granules is proportional to the square of granule diameter. The existence of large pores in granule, evidenced by FISH-CLSM imaging, was proposed to correspond to the noted size-dependent oxygen diffusivity. The phenol-fed granules exhibited a higher excellular polymer (ECP) content than the acetate-fed granules, hence yielding a lower oxygen diffusivity.
authors.affiliation: Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Z C
authors.initials: ZC
authors.lastname: Chiu
authors.forename: M Y
authors.initials: MY
authors.lastname: Chen
authors.forename: D J
authors.initials: DJ
authors.lastname: Lee
authors.forename: S T-L
authors.initials: ST
authors.lastname: Tay
authors.forename: J H
authors.initials: JH
authors.lastname: Tay
authors.forename: K Y
authors.initials: KY
authors.lastname: Show
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000332:Aerobiosis; D019149:Bioreactors / Q000382:microbiology; D004058:Diffusion; D018613:Microscopy, Confocal; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D019800:Phenol / Q000378:metabolism*; D012722:Sewage; D014871:Water Microbiology; D018508:Water Purification
chemical_list: D000085:Acetates; D012722:Sewage; D019800:Phenol; D010100:Oxygen