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ASIM Software

ASIM (Activated Sludge SIMulation Program) is a simulation program, which allows for the simulation of a variety of different biological wastewater treatment systems:
Activated sludge systems with up to 10 different reactors in series (aerobic, anoxic, anaerobic), including sludge return and internal recirculation streams, batch reactors, chemostat reactors, etc.
The program allows for the definition of process control loops (simple proportional controllers and on/off type binary controllers) and dynamic simulation of load variation (diurnal or seasonal load variation, temperature variation, variation of operational parameters such as aeration, excess sludge removal, recycle rates etc.).
Data analysis is supported by the possibility to compare observed data with simulation results in easy to use graphic support routines. Simulated results may be exported to spreadsheets for further treatment.
A menu driven user interface with context sensitive help information (by pressing F1 key), graphic support and simple file handling makes the program easy to use in class rooms, research and commercial applications.
The special feature of ASIM is that biokinetic models (the different materials or components used to characterize the wastewater and the transformation processes with relevant stoichiometry and kinetics) may be freely defined, stored and edited by the user. This allows the researcher to develop his own specific model and it allows the student to learn modelling by stepwise increase of model complexity. Simple as well as complex models are distributed together with the program in the model library. The distribution file includes copies of the Activated Sludge Model No.1 (adapted), No.2d as well as ASM3 as proposed by the IAWQ Task Group for Mathematical Modelling for Design and Operation of Biological Wastewater Treatment.

A description of the program can be found at EAWAG homepage

Examples of the application of ASIM are documented in the following publications:

W. Gujer and M. Henze (1991): Activated Sludge Modelling and Simulation, Wat. Sci. Tech., 24, Kyoto, pp 1011-1023.

W. Gujer and T. A. Larsen (1995): The Implementation of Biokinetics and Conservation Principles in ASIM, Wat. Sci. Tech, 31, No. 2, 257 - 266.

The teaching and research version of ASIM 5 is now available free of charge.
Any commercial application of ASIM requires that you obtain a commercial licence from EAWAG (order form).

English and german tutorials are available as pdf files from our download page.


İEawag, last update 27.05.2014, Manuela Frei, back to top