INTRINSIC KINETIC-PARAMETERS OF SUBSTRATE UTILIZATION BY IMMOBILIZED ANAEROBIC SLUDGE

This article presents a method for evaluating the intrinsic kinetic pa rameters of the specific substrate utilization rate (r) equation and d iscusses the results obtained for anaerobic sludge-bed samples taken f rom a horizontal-flow anaerobic immobilized sludge (HAIS) reactor. Thi s method utilizes a differential reactor filled with polyurethane foam matrices containing immobilized anaerobic sludge which is subjected t o a range of feeding substrate flow rates. The range of liquid superfi cial velocities thus obtained are used for generating data of observed specific substrate utilization rates (r(obs)) under a diversity of ex ternal mass transfer resistance conditions. The r(obs) curves are then adjusted to permit their extrapolation for the condition of no extern al mass transfer resistance, and the values determined are used as a t est for the condition of absence of limitation of internal mass transf er. The intrinsic parameters r(max), the maximum specific substrate ut ilization rate, and K-S, the half-velocity coefficient, are evaluated from the r values under no external mass transfer resistance and no in ternal mass transfer limitation. The application of such a method for anaerobic sludge immobilized in polyurethane foam particles treating a glucose substrate at 30 degrees C resulted in intrinsic r(max) and K- S, respectively, of 0.330 mg chemical oxygen demand (COD) . mg(-1) vol atile suspended solids (VSS) . h(-1) and 72 mg COD . L(-1). In compari son with the values found in the literature, intrinsic r(max) is signi ficantly high and intrinsic K-S is relatively low. (C) 1997 John Wiley & Sons, Inc.