Process Kinetics of Upflow Anaerobic Sludge Bed Reactors Treating Inhibitory Substrate

A kinetic model that accounts for the distributed fraction of methanogens (f) and granule-size distribution of upflow anaerobic sludge bed (UASB) reactors is proposed. In addition, the anaerobic degradation of phenol in four UASB reactors with various superficial flow velocity (u(s) = 0.5. 1.0, 2.0, and 4.0 m/h) was performed to generate experimental data. When using the proposed kinetic model, the calculated residual concentrations of phenol, volatile fatty acids, and chemical oxygen demand are in fairly good agreement with the experimental data. With an increase in either u(s) or volumetric loading, the granule size of the UASB reactor increases. The experimental f values decrease with an increase in volumetric loading: the f values in the lower and middle part of the sludge bed tend to be larger than those in the upper part of the sludge bed.