Effect of selected antibiotics and NSAIDs on nitrogen cycling in wastewater environments

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Resident microbial populations are an integral part of the wastewater secondary treatment process and degrade many of the complex organic compounds thereby reducing the biological oxygen demand (BOD) of the wastewater. Nitrogen (ammonia) must be removed from the wastewater since high concentrations of ammonia can be toxic and low concentrations can cause the system to stop functioning. Release of effluent containing nitrogen can cause eutrophication of the lakes and streams it is released into. Previous research has acknowledged the vast diversity of microbes in the microbial communities and has identified many of the organisms in these systems. Ammonia oxidation is carried out by ammonia-oxidizing bacteria (AOB) and recently by a second group, ammonia-oxidizing archaea (AOA). This proposal will help to understand the significance of this functional redundancy. Wastewater samples and reactors containing wastewater effluent will be sampled and subjected to chemical and molecular analysis to determine the relative abundances of each of the groups and the corresponding activity of each group. Phylogenetic shifts of AOA and AOB have been seen in soils to be caused by different environmental parameters, therefore, the activity of each group will be assessed in the presence of the antibiotics and NSAIDS, contaminants that are detected more and more frequently in municipal sewage waste streams. This research will serve to advance our knowledge of AOA in wastewater system and their role in ammonia oxidation in pharmaceutical contaminated wastewater. The apparent redundancy of ammonia oxidizers may be necessary to maintain nitrification under changing conditions seen by municipal wastewater plants.