Imperial College London


Faculty of EngineeringDepartment of Chemical Engineering

Professor of Process Systems Engineering



b.chachuat Website




609Roderic Hill BuildingSouth Kensington Campus






BibTex format

author = {Chachuat, B and Roche, N and Latifi, MA},
doi = {10.7202/705496ar},
journal = {Revue des Sciences de l'Eau},
pages = {5--26},
title = {Reduction of the ASM 1 model for optimal control of small-size activated sludge treatment plants},
url = {},
volume = {16},
year = {2003}

RIS format (EndNote, RefMan)

AB - In order to meet the stricter wastewater effluent guidelines adopted by the European Union, wastewater treatment plants require better management strategies. Wastewater treatment process models have become a major tool to design closed-loop control schemes. However, the dynamic models that are currently used in the simulation of activated sludge treatment plants (ASM 1, ASM 2 and, more recently, ASM 3 models) are highly dimensional and are not appropriate for on-line implementation (e.g., for model predictive control or optimal control). It is therefore important to develop reduced models that could be used for this purpose. A reduced model was developed to describe the behaviour of alternating activated sludge treatment plants, with the aim of applying it to the optimal control of an aeration system. The reduction scheme was based on appropriate simplifications to the ASM 1 model (which is more appropriate for open-loop control). The objective was to verify if accurate predictions could be made time periods of several hours (about 8 h). The present results are related to an existing small-size wastewater treatment plant. This plant was designed for 15000 population-equivalents (p.e.) and consists of a primary treatment stage (screening, grit removal, primary sedimentation), followed by a secondary treatment stage (biological treatment). The latter consists of a single aeration tank of about 2050 m3 equipped with 3 turbines which are operated cyclically to create alternating aerobic and anoxic conditions. Ammonia is converted into nitrate during air-on periods (nitrification step) and nitrate is subsequently removed during air-off periods (denitrification step). It is important to note that a dynamic model, based on the ASM 1 model and calibrated from a set of input/output measurements over a one-day period (CHACHUAT, 2001), was used here as a reference to perform model reduction. The following two-level simplification procedure was applied: • A homotopy method
AU - Chachuat,B
AU - Roche,N
AU - Latifi,MA
DO - 10.7202/705496ar
EP - 26
PY - 2003///
SN - 0992-7158
SP - 5
TI - Reduction of the ASM 1 model for optimal control of small-size activated sludge treatment plants
T2 - Revue des Sciences de l'Eau
UR -
VL - 16
ER -