Substrate consumption and excess sludge reduction of activated sludge in the presence of uncouplers: a modeling approach
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A mathematical model with a consideration of energy spilling is developed to describe the activated sludge in the presence of different levels of metabolic uncouplers. The consumption of substrate and oxygen via energy spilling process is modeled with a Monod term, which is dependent on substrate and inhibitor. The sensitivity of the developed model is analyzed. Three parameters, maximum specific growth rate (μ max), energy spilling coefficient (q max), and sludge yield coefficient (Y H) are estimated with experimental data of different studies. The values of μ max, q max, and Y H are found to be 6.72 day-1, 5.52 day-1, and 0.60 mg COD mg-1 COD for 2, 4-dinitrophenol and 7.20 day-1, 1.58 day-1, and 0.62 mg COD mg-1 COD for 2, 4-dichlorophenol. Substrate degradation and sludge yield could be predicted with this model. The activated sludge process in the presence of uncouplers that is described more reasonably by the new model with a consideration of energy spilling. The effects of uncouplers on substrate consumption inhibition and excess sludge reduction in activated sludge are quantified with this model.
KeywordsActivated sludge Energy spilling Modeling Sludge yield Substrate consumption Uncoupler
The authors wish to thank the Natural Science Foundation of China (50625825 and 50738006) and the Key Special Program on the Science and Technology for the Pollution Control and Treatment of Water Bodies (2008ZX07316-002 and 2008ZX07010-005) for the partial support of this study.
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