Substrate storage concepts in modeling activated sludge systems for tannery wastewaters

Abstract

In spite of a variety of model structures proposed for activated sludge systems, calibration of these models for industrial wastewaters still stands untouched. In the scope of this study, a conceptual framework for the application of ASM1, ASM3 and 3 models, involving simultaneous growth and storage under dynamic conditions is presented and these models have been used for simulating biodegradation/tannery wastewaters. A comparative representation of the modeling results obtained with 5 different models is provided. The comparison of the simulation results showed that the possibility of describing the real case increases as the model gets more detailed. Although structured models are supposed to provide a better description of the dynamic behavior observed for tannery effluents, the insufficiency experienced in the experimental determination of all the storage products when complex substrate compositions are concerned, hindered the accurate determination of model coefficients. Furthermore, modeling results for different F/M ratios clearly emphasized the challenge in the definition of readily biodegradable COD. Process stoichiometry and wastewater fractionation should be defined cautiously with additional data in order to provide substantial basis for the evaluation of the respirometric response in batch tests for model calibration.