Evaluating the Toxicity of Produced Water for Beneficial Reuse

Shale Oil and Gas
Oral Presentation

Prepared by Y. Zhang, L. Hu, P. Xu
New Mexico State University, 3035 S Espina St, Las Cruces, NM, 88003, United States

Contact Information: zhangy@nmsu.edu; 575-646-5246


The rapid development of unconventional shale oil and gas industry has brought the problems of intense freshwater consumption and significant hazardous wastewater production. Chemical parameters alone cannot ensure the safe discharge and reuse of the treated produced water due to the complexity of produced water composition. In this study, acute and chronic toxicity of produced water were assessed using marine luminescent bacterium (Vibrio fischeri), freshwater algae (Scenedesmus obliquus and Selenastrum capricornutum), and a rainbow trout (Oncorhynchus mykiss) gill epithelial cell line (RTgill-W1) to provide a rapid and effective screen for the potential impacts of untreated and treated PW. Moreover, contaminants groups including the suspended solids, soluble organics and inorganics were separated from PW and evaluated their contributions to toxicological behaviors of PW. The use of proposed toxicity assays in this study provided a rapid and effective screen for the potential impacts of untreated and treated PW. Strong correlations were found between chemical components and toxicity results. The high salinity and dissolved organics associated with PW were the foremost toxicological drivers to various organisms. Heavy metals and ammonium in PW also contributed to the overall toxicity of exposed organisms. The sensitivity of toxicity assays associated with PW exposure was deemed to be contaminant species-specific, thus, toxicity assays should be selected based on the target compounds in PW. The linkage between the chemical profiles and potential toxicity impacts explored in this study could help pinpoint target contaminants and develop effective treatment processes to achieve species-specific removal.