Static and dynamic dissolved oxygen distributions in algal–bacterial granular sludge
mapping intragranular oxygen profile and penetration under different oxygenation strategies
Zhichen Li (University of Tsukuba)
Qian Wang (TU Delft - Electrical Engineering, Mathematics and Computer Science, Ocean University of China)
Xinyu Lyu (University of Tsukuba)
Tian Yuan (University of Tsukuba)
Motoo Utsumi (University of Tsukuba)
Chul Park (University of Massachusetts)
Duu Jong Lee (City University of Hong Kong)
Mark C.M. van Loosdrecht (TU Delft - BT/Environmental Biotechnology)
Zhongfang Lei (University of Tsukuba)
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Abstract
Algal–bacterial granular sludge (ABGS) exhibits pronounced intragranular dissolved oxygen (DO) heterogeneity. However, the internal DO microenvironments under different oxygenation strategies remain insufficiently understood. In this study, intragranular DO distributions in ABGS were characterized under darkness, illumination, and artificial aeration. Results show that intragranular DO distributions varied with granule size and were differently influenced by artificial aeration and photosynthetic oxygenation. After 60 min of artificial aeration at an air uplift velocity of 2.8 cm s−1, DO at a depth of approximately 0.8 mm in granules with a diameter of around 3 mm remained nearly 0 mg L−1. In contrast, oxygen generated in situ via photosynthesis rapidly elevated intragranular DO levels, exceeding 4 mg L−1 at the same depth after 30-min illumination. This study shows that intragranular DO in ABGS can be dynamically restructured in response to distinct oxygen supply and consumption processes, which also provides an in-depth insight into better ABGS design and operation.
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File under embargo until 01-10-2026