Wastewater treatment modeling software is commonly used to aid in the design and operation of wastewater treatment facilities. This modeling software commonly utilizes activated sludge models that predict bacterial growth based on the Monod equation, which has a number of limitations. These limitations restrict the accuracy of the software and could lead to higher costs due to the overdesign of a wastewater treatment plant. An improved activated sludge model (IASM) was developed by Xu (2010) to address some of the problems associated with the Monod equation. In this study, the IASM is implemented into commercially available wastewater treatment modeling software. In this study, the BioWin simulation software is used as a reference for modeling software that incorporates the Activated Sludge Model No. 1 (ASM 1) and Activated Sludge Model No. 3 (ASM 3) as part of the overall modeling program. The equations within ASM 1 and ASM 3 that utilize the Monod equation were identified by evaluating which equations were used to model bacteriological growth. After identifying the appropriate equations, BioWin's built in Model Editor was used to modify the equations by replacing the Monod equation with the IASM equation. Simulations were then run on BioWin using ASM 1 and ASM 3 as well as the IASM modified versions of the models. Since BioWin was able to run the simulation using the modified models and no mathematical errors were encountered during the simulation, we can conclude that the IASM was successfully implemented into ASM 1 and ASM 3 within BioWin.