The University of Texas at Austin

Department of Civil Engineering


A Steady-State Wastewater Treatment Plant Modeling Program

By Luis Aburto Garnica and Gerald E. Speitel Jr., 1999

What is Steady?

Steady is a computer program that provides a generalized model to represent wastewater treatment plants. The model assumes steady-state conditions for the influents to a given plant and characterizes wastewater with the traditional environmental engineering parameters (BOD5, TSS, VSS, TKN, and NH3-N). Once a valid plant layout has been created, Steady can calculate the plant-wide mass balance and the general dimensions of the unit processes involved. Also, once the mass balance has been calculated, Steady can display the calculations performed for each unit process.

Steady provides a graphical user interface where the user can create a plant layout just by drawing a flow diagram. The interface provides dialog boxes to edit the parameters of each unit, and a menu and toolbar to access the program's commands.

Snapshots of Steady:

Figure 1 - Sample of A Plant Layout



Figure 2 - Mass Balance Summary



Figure 3 - Calculations Summary


In this version of Steady, the following unit processes have been included:

Getting Steady

Steady is available online, just click the link below to download it. You will need a decompression utility, such as WinZip or Stuffit, to expand the compressed installation files.

Download (3.7 MB)

Once you have decompressed the file, run Setup.exe to start the installation of Steady. To complete the installation you need to have write access to the Windows/System or WinNT/System directory.

For questions and comments contact Dr. Gerald E. Speitel Jr. (