COMPREHENSIVE CHEMICAL AND TOXICOLOGICAL CHARACTERIZATION OF THE TREATED HYPERSALINE-PRODUCED WATER FROM AN INTEGRATED TREATMENT TRAIN

The constituents of concern in produced water (PW) could pose a significant impact on public health and the environment due to spills and disposal. One of the barriers to using treated PW as an alternative water source is the lack of comprehensive assessment of its impacts on the environment and public health. In this study, we conducted a comprehensive chemical and toxicology assessment to determine the safe use of the treated PW in the Permian Basin after thermal distillation. Our toxicity assays involved the use of various aquatic organisms, including the luminescent bacterium Vibrio fisheri, microalgae Selenastrum capricornutum, daphnid Ceriodaphnia dubia, and zebrafish Danio rerio. We also conducted post-treatments, including zeolite adsorption, and granular activated carbon (GAC) adsorption, to further polish the thermal distillate generated from Permian Basin PW to remove residual organics and ammonia before toxicity assays. Raw PW and distillate effluents failed to meet National Pollutant Discharge Elimination System (NPDES) toxicological criteria, causing adverse effects on P. subcapitata, C. dubia and V. fischeri ranging from 84% to 100% at 100% effluent. Characterization identified 64 individual analytes in the raw PW, including 17 VOCs, 12 SVOCs, 1 PFAS, and 7 radionuclides; 65 analytes were identified in the distillate, including 15 VOCs, 14 SVOCs, 5 furans, 4 PFAs, and 5 radionuclides. Overall, the post-treatment with GAC and zeolite reduced most of the identified constituents to levels below method detection limits (MDL). This resulted in a consistent toxicity reduction across the WET tests. Specifically, there were no observable adverse effects for P. subcapitata, C. dubia, and V. fischeri (no observed effect concentration >100%). Our findings demonstrate that PW, after appropriate treatment, has good potential to be discharged or reused safely.