ASIM (Activated Sludge SIMulation Program) is a simulation program, which
allows for the simulation of a variety of different biological wastewater
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