Relative Efficacy of Intrinsic and Extant Parameters for Modeling Biodegradation of Synthetic Organic Compounds in Activated Sludge: Steady-State Systems

The performance of intrinsic and extant kinetic parameters as predictors of synthetic organic compound (SOC) concentration in biotreatment systems operated at steady state was evaluated. Two laboratory-scale, completely mixed activated-sludge systems were sampled on a routine basis, and SOC concentrations were quantified using gas chromatography with flame-ionization detection coupled with solid-phase microextraction for analyte concentration. At the same time, intrinsic and extant respirometric tests were performed periodically, and the kinetic parameter estimates obtained were used to predict effluent SOC concentrations for comparison with the measured values. Out of 28 comparisons that could be made between intrinsic and extant predictions, extant parameters were superior in 27 cases and intrinsic parameters were comparable, at best, to extant parameters in the remaining case. Given their superior performance and relative ease of measurement, extant parameters are preferable for use in design and operational decision-making.