New Mexico Geological Society Annual Spring Meeting — Abstracts

Extracting crude oil from shale and tight oil resources using horizontal drilling and hydraulic fracturing generates a significant waste stream called produced water (PW). Thoroughly treated PW could be an alternative water resource in water scarcity regions. In addition to the conventional water quality analysis, toxicological assessments are needed for the safe discharge and reuse of treated PW. Herein, this study aims to evaluate the toxicological effects of treated PW by thermal and membrane processes on viability, estrogenic activity (EA), and the activation of the aryl hydrocarbon receptor (AhR) of multiple human cell lines (MCF-7, HEK293, HepG-2, and A-549) utilizing in vitro bioassays. Raw PW from permian basin, partially desalinated effluent (PDE), thermal distillate (TD), and final effluents (FE) from treatment trains were collected to assess the toxicity. The CellTiter-Glo® 2.0 assay was performed to assess viable cell count after exposing raw and treated PW. The EA and activation of the AhR were obtained by gene expressions of the CYP19A1 and CYP1B1 of MCF-7 cells. Exposure of 6.25 % raw PW used in the study caused approximately 10 - 50 % reduced cell viability for all cell types, indicating the high toxicity of untreated PW. The TD and FE did not cause reduced viability for all for cell types. However, PDE caused significantly reduced cell viability due to its high salinity (TDS = 26,100 mg/L). The estrogenic activity was increased when exposure to raw PW, as indicated by upregulated CYP19A1, whereas no estrogenic activity was detected in all treated PW samples. The CYP1B1 gene were also upregulated by raw PW, TD, and PDE, revealing the presence of AhR activation compounds. The FE after the membrane process had unchanged CYP1B1 gene expressions compared to the control.