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 stochiometry 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.

Keywords:

• Activated sludge model No. 1
• ASM1
• activated sludge model No. 3
• ASM3
• modeling
• substrate storage
• tannery wastewaters

Acknowledgments

This study was conducted as part of the sponsored research activities of The Environmental Biotechnology Centre of the Scientific and Technical Council of Turkey (TUBITAK). The authors deeply acknowledge colleagues, Didem Okutman Tas, Hakan Dulkadiroglu and Ebru Dülekgürgen at ITU Enviromental Biotechnology Group for their contribution to the experimental work carried out for this study.