A new activated sludge model, called MantisIW, has been developed for industrial wastewater treatment plants (WWTPs). The model provides a general modeling framework for industrial activated sludge plants and allows for flexibility in handling a wide variety of industrial wastewaters such as those encountered in the petroleum, petrochemical, organic chemical, pulp and paper, pharmaceutical, and food and beverage industries. MantisIW combines the ASM1 biological model (Henze et al., 2000) with a revised categorization of the influent COD, multiple degradation and transformation pathways for the new COD categories, the modeling of sulfur compounds, colloidal material, and toxics, and the modeling of nutrient and alkalinity limitations on biological growth. The addition of partitioning to different media, including effluent, air emissions and residual solids captures the unique nature of the fate of industrial wastes. The default kinetic and stoichiometric parameter values in the model are taken from the literature and the TOXCHEM+ (Hydromantis, Inc., 2006b) predictive fate modeling package. Future work will include fine-tuning of the kinetic and stoichiometric parameter values using historical dynamic operating data from industrial WWTPs.