Bacteria play an important role in oxidation and stabilization of organic and inorganic matter
in wastewater treatment plant. This paper presents the development of mathematical model to study the
effect of chromium on heterotrophic bacteria in waste stabilization pond. The governing equation of the
model is based on the Haldane equation. The model developed reflects the mortality rate of heterotrophic
bacteria at variable pH and concentration of chromium. To verify the computed results a series of laboratory
experiments has been carried out, the predicted mortality rate was obtained from these models and compared
with experimental data. The correlation coefficient R2 was 0.87.