Integrated Assessment of Whole Effluent Toxicity Tests and Chemical Characterization of Treated Permian Basin Produced Water

Abstract

Produced water (PW) from energy extraction operations in the Permian basin is managed using a range of treatment, recycle, and disposal options. There is interest in the research community to evaluate the beneficial use of treated PW outside the oil field. The present work provides a detailed chemical characterization of the PW that has undergone treatment to remove salts, organics, and other constituents. The treated PW was further evaluated using a range of whole effluent toxicity test species, such as fish and invertebrates, terrestrial species, and in vitro bioassays. Toxicity modeling was used to integrate analysis of the chemical and toxicology data to estimate the relative contribution of different chemical constituents in the treated PW. The results indicate that ammonia is the largest contributor to the observed aquatic toxicity in the treated PW and that other constituent classes like hydrocarbons and metals are minor contributors to the observed toxicity to aquatic organisms. There was no observed cytotoxicity tested with extracts of the organic chemicals from the treated PW, which is consistent with the aquatic toxicity tests, and the terrestrial species were less sensitive than the aquatic species. These results can inform management options for the treated PW including potential end-use considerations.

We demonstrate that chemical concentration data can be used to interpret whole effluent toxicity data to evaluate safety of treated produced water.