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Kinetic model of a granular sludge SBR: Influences on nutrient removal
Author(s) -
de Kreuk M.K.,
Picioreanu C.,
Hosseini M.,
Xavier J.B.,
van Loosdrecht M.C.M.
Publication year - 2007
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.21196
Subject(s) - granule (geology) , anoxic waters , sequencing batch reactor , chemistry , effluent , oxygen , chemical oxygen demand , denitrification , pulp and paper industry , phosphate , nitrogen , nutrient , ammonia , batch reactor , environmental engineering , environmental chemistry , sewage treatment , environmental science , materials science , biochemistry , catalysis , organic chemistry , engineering , composite material
A mathematical model was developed that can be used to describe an aerobic granular sludge reactor, fed with a defined influent, capable of simultaneously removing COD, nitrogen and phosphate in one sequencing batch reactor (SBR). The model described the experimental data from this complex system sufficiently. The effect of process parameters on the nutrient removal rates could therefore be reliably evaluated. The influence of oxygen concentration, temperature, granule diameter, sludge loading rate, and cycle configuration were analyzed. Oxygen penetration depth in combination with the position of the autotrophic biomass played a crucial role in the conversion rates of the different components and thus on overall nutrient removal efficiencies. The ratio between aerobic and anoxic volume in the granule strongly determines the N‐removal efficiency as it was shown by model simulations with varying oxygen concentration, temperature, and granule size. The optimum granule diameter for maximum N‐ and P‐removal in the standard case operating conditions (DO 2 mg L −1 , 20°C) was found between 1.2 and 1.4 mm and the optimum COD loading rate was 1.9 kg COD m −3 day −1 . When all ammonia is oxidized, oxygen diffuses to the core of the granule inhibiting the denitrification process. In order to optimize the process, anoxic phases can be implemented in the SBR‐cycle configuration, leading to a more efficient overall N‐removal. Phosphate removal efficiency mainly depends on the sludge age; if the SRT exceeds 30 days not enough biomass is removed from the system to keep effluent phosphate concentrations low. Biotechnol. Bioeng. 2007;97: 801–815. © 2006 Wiley Periodicals, Inc.