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Title: Temporal trends of perfluoroalkyl substances in limed biosolids from a large municipal water resource recovery facility

item ARMSTRONG, DANA - University Of Maryland
item LOZANO, NURIA - Cantabria University
item Rice, Clifford
item RAMIREZ, MARK - District Of Columbia Water & Sewer Authority (DCWASA)
item TORRENTS, ALBA - University Of Maryland

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2015
Publication Date: 1/15/2016
Citation: Armstrong, D.L., Lozano, N., Rice, C., Ramirez, M., Torrents, A. 2016. Temporal trends of perfluoroalkyl substances in limed biosolids from a large municipal water resource recovery facility. Journal of Environmental Management. 165:88-95.

Interpretive Summary: Land application of biosolids as a soil amendment has numerous benefits, including nutrient addition, soil structure improvement, and reuse of a waste that encourages sustainability. However, negative qualities in biosolids are also present. Notable for this study are perfluoroalkyl (PFAS) substances which are widely used industrial products that are released in large quantities to waste water treatment plants. This mixed compound group moves almost entirely into the biosolids. These PFAS polymer materials release smaller molecular forms that are of great concern toxicologically. Because of the possible release of these toxic PFAS compounds from the land applied biosolids, this study examined the concentrations that were occurring in biosolids and determined whether their levels were changing over a nine year period. Samples of biosolids from a local waste water treatment plant were collected 4-6 times per year from 2005 to 2013 and analyzed for 22 likely PFAS compounds. Seven were found at levels above detection on a routine basis and the highest three were measured in the mid 20 ppb levels. None were found to show any statistical time trend for increase our decrease over the sampled period, even though restrictions had been imposed to limit their production starting as early as the year 2000. Information on the emission rates of PFAS materials from biosolids is needed by managers of these treatment facilities in order to improve treatment designs to reduce their release.

Technical Abstract: While the recycling of wastewater biosolids via land-application is a commonly used practice for nutrient recovery and soil reclamation, concerns remain that they may become sources of toxic, persistent organic pollutants to the environment. This study concentrates on assessing the presence and the temporal trends of 12 perfluoroalkyl substances (PFASs) in limed, Class B biosolids from a WWTP in the Mid-Atlantic region of the United States. PFASs are of significant concern due to their extensive presence and persistence in environmental and biotic samples worldwide, most notably human blood samples. Class B biosolids were collected from the WWTP, prior to land-application, approximately every two to three months, from 2005 to 2013. Overall, this study illustrates that concentrations of the 7 detectable PFAS compounds remained unchanged over the 8-year period, a result that is consistent with other temporal studies of these compounds in sewage sludges. From these analyzed compounds, the highest mean concentrations observed over the study period were 25.1 ng/g dw, 23.5 ng/g dw, and 22.5 ng/g dw for perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS), respectively, and these compounds were detected at concentrations 2.5 to 5 times higher than the remaining, detectable, PFASs. Furthermore, it was observed that PFOS, while demonstrating no overall change during the study, exhibited a visible spike in concentration from late 2006 to early 2007. This study also demonstrates that the use of glass jars with polytetrafluoroethylene-lined lids, a common storage method for environmental samples, will not influence PFOA and PFNA concentrations in archived biosolids samples.