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theses

Pharmaceuticals and personal care products (PPCPs) are used on a daily basis by people worldwide and are released into the environment by human excretion as well as improper disposal. These emerging contaminants make their way to a wastewater treatment plant where they are incompletely removed and are released into the environment via wastewater effluent. Atenolol, a beta-blocker, is commonly found in wastewater, treated effluent, and in the open environment. This research investigated the microbial transformation of atenolol under methanogenic conditions. Two sets of enrichment cultures were established with sediment from Iona marsh and from anaerobic digester sludge from a wastewater treatment plant as inoculum; both were fed 0.5 mM of atenolol. The Iona marsh primary enrichment cultures completely removed atenolol by day 45 with the formation of the metabolite atenolol acid. The anaerobic sludge enrichment cultures completely removed atenolol by day 98 with the formation of atenolol acid. Atenolol amended cultures produced more total gas and methane than the unamended backgrounds in both enrichment culture set-ups. Results from the Anaerobic Toxicity Assay (ATA) and Biochemical Methane Potential (BMP) showed that atenolol was not chronically toxic and has the potential to be biodegraded. However, atenolol was only transformed. Using 16S rDNA, the microbial community was characterized via Illumina sequencing and displayed a difference between the atenolol transforming communities compared to unamended background controls; addition of atenolol selected for a fermentative and methanogenic community. This is the first demonstration of the transformation of atenolol to atenolol acid under anaerobic conditions to our knowledge. Atenolol acid was not further degraded or transformed in either culture set-up throughout the course of the experiment. These findings indicate atenolol can be transformed to atenolol acid in methanogenic environments such as anaerobic sediments, digesters, and the rumen, but the metabolite atenolol acid is recalcitrant in these environments. This finding provides further support that pharmaceutical metabolites remain in the environment and that these metabolites should also be tested like pharmaceuticals to see if they elicit adverse effects on the organisms living in the environment. Another set of enrichment cultures were set up in the same manner but with the pharmaceutical ibuprofen, a Nonsteroidal anti-inflammatory drug (NSAID), that is also found throughout the environment and in wastewater treatment plants. Ibuprofen was not degraded in either set of cultures, but the ibuprofen amended cultures had higher total gas and methane production than the unamended backgrounds. Results from the Anaerobic Toxicity Assay (ATA) and Biochemical Methane Potential (BMP) showed that ibuprofen was not chronically toxic and has the potential to be biodegraded; however, it was not biodegraded. Community analysis of the ibuprofen amended Iona cultures revealed that ibuprofen selected for a methanogenic community.

ETD_7846

M.S.

Includes bibliographical references

by Julia K. Campbell

doi:10.7282/T3RR21PN

ETD graduate

The author owns the copyright to this work.