This repository contains the different Activated Sludge Models implementations developed between Lund University and the Technical University of Denmark.

1. ASM1, 2d and 3 implemented in BSM1

This implementation of ASM1, 2d and 3 account implemented in the BSM1 layout accounts for 1) reactive settling and 2) electron dependency. The Main developers are: Xavier Flores-Alsina, Krist V. Gernaey, and Ulf Jeppsson. The model is described in the following paper:

Flores-Alsina X., Gernaey K.V. and Jeppsson, U. (2012). Benchmarking biological nutrient removal in wastewater treatment plants: influence of mathematical model assumptions. Water Sci. Technol., 65 (8): 1496-1505.

This version of the model is adapted to be run in Matlab 2019b (or newer).

2. ASM1, 2d and 3 implemented in BSM1 (with pH calculations)

The previous implementation is upgraded with aqueous phase chemistry models accounting for 1) ion pairing and 2) activity corrections. The latter allows you to predict weak-acid base conditions and therefor pH. The main developers are: Xavier Flores-Alsina, Christian Kazadi Mbamba, Kimberly Solon, Darko Vrecko, Stephan Tait, Damien J Batstone, Ulf Jeppsson, Krist V. Gernaey. The model is described in the following paper:

Flores-Alsina X, Kazadi-Mbama C., Solon K., Vrecko D., Tait S., Batstone D., Jeppsson U. and Gernaey K.V. (2015). A plant wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment models. Water Research, 85, 255-265.

This version of the model is adapted to be run in Matlab 2019b (or newer).

3. ASM2d implemented in an industrial bio-reactor (with N2O emissions)

The process kinetics and stoichiometry are adapted from the Activated Sludge Model No. 2d (ASM2d). The original mathematical structure was modified to incorporate ammonium oxidizing bacteria (AOB) inhibition by NO2−. To comprehensively capture N2O production, the model includes three biological N2O production pathways: 1) Nitrifier nitrification pathway (NN pathway), 2) Nitrifier denitrification pathway (ND pathway) and 3) Heterotrophic denitrification pathway (DEN pathway). The gas-liquid (G-L) transfer processes, are modeled differently across 1) anoxic and 2) aerobic stages. The Main developers are: The Main developers are: , and Tianyu Lei, Xavier Flores-Alsina, Krist V. Gernaey. The model is described in the following paper:

Lei, T., Whale-Obrero, J., Larsen, S. B., Kjellberg, K., Gernaey, K. V., & Flores-Alsina, X. (2025). Dynamically predicting nitrous oxide emissions in a full-scale industrial activated sludge reactor under multiple aeration patterns and COD/N ratios. Water Research. 123379.

This version of the model is adapted to be run in Matlab 2022b (or newer).