The most widely used method of wastewater treatment is biological treatment. The use of kinetic models to describe the behavior of a biological wastewater treatment process has become widely accepted practice. The most often used kinetic models include those developed by Eckenfelder, McKinney, Lawrence and McCarty, and Gaudy. All of these models contain kinetic constants, and the usefulness of each model is a function of the reliability of the kinetic constants. However, there has not been enough information available to establish reliable values for these kinetic constants for industrial wastewaters. This continued project has determined the biokinetic constants and fate for twelve additional toxic organic pollutants when present in a highly biodegradable wastewater. The normal approach for determining biokinetic constants has been to plot the average values. This approach masks the actual scatter of the data. This study has produced a methodology for analysis of the test results from biological activated sludge systems for determining the biological variability inherent in these types of systems. This study also investigated the possibility of predicting the fate and effluent concentrations of the various priority pollutants. It was found that good predictions for the priority pollutants can be made.