Horizontal drilling and hydraulic fracturing techniques have experienced a rapid increase over the past decade with regard to conventional and unconventional energy production. The produced water generated contains a broad variety of hazardous substances classified as a major concern for the environment and human health. In this sense, many countries have implemented stringent regulatory standards for discharging produced water from oil and gas extraction process. For their treatment, most of the technologies studied have presented unveiled disadvantages mainly due to their acquisition and exploitation costs. The use of eco-friendly water technologies can contribute to decrease the load of hazardous chemicals entering into the environment whilst minimizing the energy consumption. However, while many studies have evaluated the elimination of target pollutants, few attention has been paid to the study of the transformation products (TPs) generated.  In this study, eco-friendly microalgae treatments have been performed for the elimination of the surfactant benzalkonium chloride in spiked seawater and produced water. The experiments were carried out in an own-design photobioreactor using eight different marine microalgae strains. Samples were analyzed in a liquid-chromatography system coupled to high-resolution mass spectrometry (LC-HRMS) using in-source ion fragmentation for the identification of the isomer intermediates generated. Results reveal complete elimination of benzalkonium chloride after 14 days of treatment using <i>T. suecica</i> microalga stain in fortified seawater. However, this microalga achieved lower removal rates (54%) treating real produced water. In both cases, the major intermediates generated were isomeric hydroxyl compounds and unsaturated intermediates generated through further dehydration step. The intermediates generated were evaluated in terms of anticorrosion activity regarding their estimated hydrophobicity in water. As a conclusion, <i>T. suecica</i> was the only microalgae capable to biodegrade the parent compound into a more hydrophilic intermediates decreasing their amphiphilic properties, and thus, their activity as surfactants and corrosion inhibitors.

Microalgae-based technology for removal of benzalkonium chloride in oil and gas produced water: Biotransformation and environmental effects

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.