Mathematical modeling of activated sludge systems is used widely for plant design, optimization, operator training, model-based process control system design and in research. The quality of simulation studies can vary strongly depending on the project objectives, resources spent and expertise available. Consideration has to be given to the model accuracy and the amount of time required to carry out a simulation project with the aim to produce the required accuracy. A great variety of approaches and insufficient documentation make quality assessment and comparability of simulation results difficult or almost impossible. A general framework for the application of activated sludge models is needed in order to overcome these obstacles.
Several guidelines have been developed during the last years around the world focusing on different aspects of simulation projects. To synthesize the available experience into an internationally recognized industry standard, the International Water Association (IWA) formed a Task Group on "Good Modelling Practice - Guidelines for Use of Activated Sludge Models" (GMP Task Group). The objective of the GMP Task Group was to prepare a Scientific and Technical Report that describes a Good Modeling Practice with activated sludge systems. Publication of the report is foreseen for 2012 (Rieger et al., 2012).