Critical review of activated sludge modeling: State of process knowledge, modeling concepts, and limitations

• Published in: Biotechnology and bioengineering Vol. 110; no. 1; pp. 24 - 46
• Main Authors: Hauduc, H., Rieger, L., Oehmen, A., van Loosdrecht, M.C.M., Comeau, Y., Héduit, A., Vanrolleghem, P.A., Gillot, S.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-01-2013; Wiley Subscription Services, Inc; Wiley
• Subjects: Activated sludge; ASM; Bacteria; Biochemistry; Bioengineering; biological nutrient removal; Decay; Environmental Sciences; Fermentation; Hydrogen-Ion Concentration; Hydrolysis; Icons; Kinetics; model selection; modeling concepts; Models, Biological; Organisms; Phosphorus - chemistry; Representations; Sewage; Sludge; Waste Disposal, Fluid; Water Purification; Water treatment; MODELLING CONCEPTS; ASM; BIOLOGICAL NUTRIENT REMOVAL; MODEL SELECTION
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.24624

This work critically reviews modeling concepts for standard activated sludge wastewater treatment processes (e.g., hydrolysis, growth and decay of organisms, etc.) for some of the most commonly used models. Based on a short overview on the theoretical biochemistry knowledge this review should help model users to better understand (i) the model concepts used; (ii) the differences between models, and (iii) the limits of the models. The seven analyzed models are: (1) ASM1; (2) ASM2d; (3) ASM3; (4) ASM3 + BioP; (5) ASM2d + TUD; (6) Barker & Dold model; and (7) UCTPHO+. Nine standard processes are distinguished and discussed in the present work: hydrolysis; fermentation; ordinary heterotrophic organisms (OHO) growth; autotrophic nitrifying organisms (ANO) growth; OHO & ANO decay; poly‐hydroxyalkanoates (PHA) storage; polyphosphate (polyP) storage; phosphorus accumulating organisms PAO) growth; and PAO decay. For a structured comparison, a new schematic representation of these processes is proposed. Each process is represented as a reaction with consumed components on the left of the figure and produced components on the right. Standardized icons, based on shapes and color codes, enable the representation of the stoichiometric modeling concepts and kinetics. This representation allows highlighting the conceptual differences of the models, and the level of simplification between the concepts and the theoretical knowledge. The model selection depending on their theoretical limitations and the main research needs to increase the model quality are finally discussed. Biotechnol. Bioeng. 2013; 110: 24–46. © 2012 Wiley Periodicals, Inc.
The modeling concepts of seven of the most commonly used activated sludge models (ASM1, ASM2d, ASM3, Barker & Dold, UCTPHO+, ASM2d+TU Delft, ASM3+Eawag Bio‐P) are reviewed process by process. Based on a short overview of the relevant biochemistry knowledge, the modeled processes are critically compared through a new schematic representation. Theoretical limitations and the main research needed to increase model quality are discussed.