Biological Treatment of Perchlorate and Nitrate Contaminated Drinking Water - Optimization of System Performance Using Microbial Community Characterization.

Abstract

Among many strategies to solve water quality problems, environmental biotechnology provides attractive solutions to remove contaminants from drinking water sources in more sustainable ways than traditional methods. In this dissertation, efforts were presented to optimize and apply biologically active carbon (BAC) reactors to remove inorganic contaminants (i.e., perchlorate and nitrate) from groundwater and synthetic groundwater. The optimization strategies included promoting biological activity by adding phosphorus, utilizing the activated carbon adsorption capacity and an intracellular storage mechanism to control effluent electron donor residual, and controlling microbial contamination by disinfecting reactor effluent with monochloramine. In order to study the perchlorate reducing bacterial populations insides bioreactors, a solution-based hybridization assay using peptide nucleic acid molecular beacon probes was developed to quantify 16S ribosomal RNA of Dechloromonas and Azospira. In addition, molecular techniques such as clone library and real-time polymerase chain reaction were applied to monitor specific microbial populations in BAC and other biofilm reactors after changes in various reactor operating conditions. With the knowledge obtained from the microbial studies, the correlation among reactor operation, microbial community, and reactor performance was elucidated. The use of environmental biotechnology, complemented by molecular studies of the microbial communities involved, as demonstrated in this dissertation, provides a promising avenue to mitigate a variety of water quality problems.