Diffusivity of oxygen in aerobic granules

✍ Scribed by Z.C. Chiu; M.Y. Chen; D.J. Lee; S.T.-L. Tay; J.H. Tay; K.Y. Show

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 303 KB
• Volume: 94
• Category: Article
• ISSN: 0006-3592
• DOI: 10.1002/bit.20862

✦ Synopsis

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 × 10^−9^ m^2^/s of 1.28–2.50 mm acetate‐fed granules, and 2.50–7.65 × 10^−10^ m^2^/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. © 2006 Wiley Periodicals, Inc.