Stoichiometric and kinetic model parameters for microbial transformations of suspended solids in combined sewer systems

Biotransformation of wastewater particles with different settling velocitie s has been investigated based on analysis of long term oxygen uptake rate ( OUR) measurements and a conceptual model describing aerobic transformations of organic matter has been used for interpretation. No significant changes in the biodegradability of wastewater particles with different settling ve locities were found. In this respect wastewater particles differed from ear lier findings for sewer sediments. Methods for determination of model param eters describing aerobic heterotrophic biomass growth and wastewater substr ate transformations have been derived and values estimated by adding readil y biodegradable substrate to wastewater particles and sewer sediments. The validity of modeling results was subsequently tested. The model was capable of predicting biomass growth for long term measurements correctly and to s imulate the OUR satisfactorily, however, peaks in OUR were difficult to sim ulate, probably because of a simplified description of hydrolysis used in t he concept. Generally, it can be recommended to use OUR measurements, inter preted by a conceptual model describing aerobic transformations df organic matter, as a valuable methodology for characterization of wastewater partic les as well as suspended sewer sediments in terms of GOD-fractions and rela ted biotransformations. (C) 1999 Elsevier Science Ltd. All rights reserved.