Bruce Rittmann's research combines concepts and techniques from engineering with those from microbiology, biochemistry, microbial ecology, and geochemistry. His work ranges from fundamental studies, such as on the genetics and ecology of nitrifying bacteria, to applied studies, such as evaluating the performance of in situ bioremediation. His work with the Institute was to examine bioremediation as a cost-effective option for remediation of contaminated soils encountered in transportation activities.