Degradation of particulate organic matter – a comparison of different model concepts

From the results of investigations at full-scale and pilot plants, it has been found that with ‘usual’ parameters the ASM1 is only valid for a small range of SRT as well as of oxic reactor section (V_OX/V). To make ASM1 applicable to a wider range of SRT the very slowly biodegradable particulate organic matter has to be taken into consideration. This fraction can be interpreted as part of the ‘heterotrophic biomass’ X_B,H which requires modification of the values for the ‘heterotrophic decay rate’ b_H and for the fraction of X_I in the influent. In order to distinguish between ‘active heterotrophic biomass’ (X_B,H) and the very slowly biodegradable substrate it seems to be useful to inkoduce the latter mass fraction as a new model component (X_V) into the ASM1. This extended simulation model has given reasonable results for different activated sludge systems.