Occurrence and biodegradability studies of selected pharmaceuticals and personal care products in sewage effluent

Abstract

It is important to determine the behavior of constituents in treated sewage during soil aquifer treatment for water recycling. A collaborative project with Herman Bouwer published in 1984 documented the fate and occurrence of Priority Pollutants during groundwater recharge using wastewater with application to water reuse and agricultural systems. New compounds are continually being manufactured and released to the environment. The interest today has shifted to the behavior of emerging contaminants. One important class of emerging contaminants is pharmaceuticals and personal care products (PPCPs). The hazards to the environment and human health of trace levels of PPCPs in water supplies are poorly understood. A multi compound method using solid phase extraction and chemical derivatization with pentafluorobenzylbromide, followed by analysis via gas chromatography/mass spectrometry was used to study the occurrence and removals of 18 PPCPs in a local wastewater treatment plant (WWTP). Overall, 16 out of the 18 selected PPCPs, which span a range of therapeutic classes and some commonly used personal care products, were detected in raw sewage samples collected from the Baltimore Back River WWTP. Ten of the 18 selected PPCPs were detected in the treated sewage effluent, signifying incomplete removal for the majority of the PPCPs during the wastewater treatment processes. The majority of the target analytes were detected in both the influent and effluent WWTP samples at μg/L levels, although some PPCPs (e.g., naproxen and ibuprofen) were encountered at μg/L levels. Biodegradation is an important process for wastewater and soil aquifer treatment. Aerobic batch biodegradation (using activated sludge as microbial inocula) experiments were conducted to gain insight into the biodegradation behavior of our target PPCPs at initial concentrations of 50, 10, and 1 μg/L. Sterile control studies showed no loss of our target PPCPs during the entire incubation period, and sorption to the biomass was found to be negligible for all testing conditions. Biodegradation results were not sensitive to the initial concentration and showed that 13 of the 18 PPCPs tested exhibited biotransformations greater than 80% after 50 days of incubation. Phenytoin, 5-fluorouracil, and diclofenac were the only three compounds with removals less than 60%. The occurrence study revealed the presence of PPCPs in sewage effluents, and the biodegradation study suggests that biotransformation is a possible removal mechanism for PPCPs during groundwater recharge or soil aquifer treatment for water recycling.