Personal tools
You are here: Home GMP GUIDELINES



More information on ordering a copy can be found here.

Guidelines are needed to enhance the quality and efficiency of activated sludge (AS) modelling projects. These guidelines should include practical protocols on how to use AS models and specific aspects concerning the interaction between modellers and clients. Providing this information is the main objective of the IWA Task Group 'Good Modelling Practice (GMP) - Guidelines for Use of Activated Sludge Models'. Therefore, a unified protocol was developed combining (i) existing guidelines developed in the wastewater treatment field and (ii) key elements pointed out in more general procedures elaborated in the context of water management. The proposed protocol includes 5 main steps:

  1. Project definition
  2. Data collection and reconciliation
  3. Plant model set-up
  4. Calibration and validation

  5. Simulation and result interpretation

The unified protocol forms the framework of the complete GMP Guidelines which will be published as an IWA Scientific Technical Report. Click here to get more publishing information on the GMP STR or see below for a Table of Contents.



Error-free Gujer Matrices

One task of the GMP work was to check and correct published biokinetic models. A PhD student from Cemagref/Université Laval, Hélène Hauduc, investigated 7 published models for typing errors, inconsistencies and gaps in the model publications. Be careful, there are plenty of errors! The results were published in Water Science & Technology:

H. Hauduc, L. Rieger, I. Takács, A. Héduit, P.A. Vanrolleghem and S. Gillot (2010). A systematic approach for model verification: application on seven published Activated Sludge Models. Water Science & Technology, 61(4), 825-839.


The quality of simulation results can be significantly affected by errors in the published model (typing, inconsistencies, gaps or conceptual errors) and/or in the underlying numerical model description. Seven of the most commonly used activated sludge models have been investigated to point out the typing errors, inconsistencies and gaps in the model publications: (1) ASM1 (Henze et al., 1987; republished in Henze et al., 2000a); (2) ASM2d (Henze et al., 1999;  republished in Henze et al., 2000b); (3) ASM3 (Gujer et al., 1999; corrected version published in Gujer et al., 2000); (4) ASM3+Bio-P (Rieger et al., 2001); (5) ASM2d+TUD (Meijer, 2004); (6) New General (Barker and Dold, 1997); (7) UCTPHO+ (Hu et al., 2007).

A systematic approach to verify models by tracking typing errors and inconsistencies in model development and software implementation is proposed. Then, stoichiometry and kinetic rate expressions are checked for each model and the errors found are reported in detail. A spreadsheet (found at provides corrected matrices with the calculations of all stoichiometric coefficients for the discussed biokinetic models and gives an example of proper continuity checks.

The corrected Gujer matrices can be downloaded as an MS Excel spread-sheet. A comparison of different parameter naming rules including the new IWA Notation (Corominas et al., 2010) can be found here.


 IWA Scientific Technical Report


A.    Acknowledgements
B.    List of GMP Task Group Members

1    Introduction
2    State-of-the-Art in Activated Sludge Modelling

3    Available Protocols
4    The GMP Unified Protocol
5    Unified Protocol Steps

   5.1    Project Definition

   5.2    Data Collection and Reconciliation

   5.3    Plant Model Set-up

   5.4    Calibration and Validation

   5.5    Simulation and Result Interpretation

6    The GMP Application Matrix
7    Using the GMP Unified Protocol by Example
8    Use of Activated Sludge Models for Industrial Wastewater
9    FAQs
10  Glossary

Appendices A-H


There is also an IWA WaterWiki website with additional material


Document Actions