Chiu Z.C.Chen M.Y.Lee D.J.Tay S.T.-L.Tay J.H.Show K.Y.2019-05-142019-05-14200600063592https://scholars.lib.ntu.edu.tw/handle/123456789/408027This 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 ¡Ñ 10-9 m 2/s of 1.28-2.50 mm acetate-fed granules, and 2.50-7.65 ¡Ñ 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. ? 2006 Wiley Periodicals, Inc.Aerobic granuleCarbon sourceDynamic testOxygen diffusivitySize[SDGs]SDG6[SDGs]SDG14journal article10.1002/bit.208622-s2.0-33745184872https://www.scopus.com/inward/record.uri?eid=2-s2.0-33745184872&doi=10.1002%2fbit.20862&partnerID=40&md5=ce701124d97cb7f77133d0e523b2813a