Student Research: Thomas J. Theno

Microbial Assay of Toxicity Associated with Biological Treatment of Water Contaminated with Chlorinated Organics


Chlorinated organic compounds are a class of pollutants which have been released into the environment in large quantities from a multitude of sources. Because of their physical and chemical properties, these compounds possess sufficient mobility to reach groundwater and sediments. In these environmental compartments chlorinated organics exert toxicity and selective pressures on the indigenous microbial populations. Due to the growing dependence of public water waupplies on groundwaters, their contamination by chlorinated organic hydrocarbons is a public health concern. Biological assays have been developed, in response to this concern, to determine the toxicity of water containing such chemicals. In this study, the Microtox Bioassay has been used as a means of quantifying toxicity in contaminated waters before and after biological treatment.

Biological reactor schemes have been develped to investigate biodegradability, mechanisms and kinetics of chlorinated organic compounds by microbial populations in mixed and pure cultures. Assessment of reactor performance in degradation studies traditionally involves monitoring the disappearance of contaminant concentrations as a measure of treatment effectiveness. Given the potential for the production of toxic intermediates and end products of biotransformation, simply obseving contaminant disappearance may not adequately characterize bioreactor performance with regard to environmental impacts of bioreactor effluents.

Taken from the beginning of thesis.