Fate of Endocrine Disruptors, Antibiotics and Pharmaceuticals in Wastewater Treatment Plants

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Project Period: 
Collaborating Institution(s): 
Iowa Department of Natural Resources (IDNR)
Project Investigator(s): 
Gene Parkin, Craig Just, Department of Civil and Environmental Engineering, The University of Iowa

Biosolids are generally defined as the end-product of production and treatment of sludges generated during wastewater treatment. Beneficial uses of biosolids (e.g., land application, landfill covers, etc.) are expected to increase in the coming years. Wastewaters from domestic and industrial sources are known to contain relatively low concentrations of endocrine disruptors, antibiotics and pharmaceuticals. Most of what is known about the fate of these compounds comes from measurements taken before and after treatment of the liquid component of the wastewater. Very little is known about the fate of these compounds during processing of the solids generated during wastewater treatment. Many of these compounds are likely to partition onto particulate matter due to their hydrophobic nature. Thus, it is important to understand the fate of these compounds during the production and use of biosolids. Aqueous samples collected at points throughout a wastewater treatment plant were processed and analyzed for acetaminophen, caffeine, cotinine, ibuprofen, 4-nonylphenol, sulfamethoxazole, triclosan, and trimethoprim. Most aqueous phase removal occurred during primary clarification and/or activated sludge treatment while little or no aqueous phase removal resulted from secondary clarification or chlorination/dechlorination. Sorption isotherms determined for each compound on biosolids from the plant indicated compound specific sorption behavior. Caffeine, cotinine and acetaminophen were significantly removed from the aqueous phase during activated sludge treatment. This implicates biotransformation as a primary removal process given the low sorption potential of these chemicals. Sulfamethoxazole and trimethoprim also have low sorption potential, but are more chemically stabile such that only a small quantity of each was removed during activated sludge treatment. Ibuprofen, 4-nonylphenol and triclosan were significantly removed from the aqueous phase during activated sludge treatment, likely as a result of sorption processes as evidenced by high log Kow values and high concentrations of triclosan and 4-nonylphenol in analyzed biosolids.