What do we need to do with produced water before we can re-use, recycle or dispose of it? We must treat it. We can reuse it for hydraulic fracturing with minimal treatment because the hydraulic fracturing process has evolved to use clean brines with minimal treatment.1Scanlon, B. R., Reedy, R. C., Xu, P., Engle, M., Nicot, J. P., Yoxtheimer, D., Yang, Q. & Ikonnikova, S. (2020). Can We Beneficially Reuse Produced Water from Oil and Gas Extraction in the US? Science of the Total Environment, 717. However, treating produced water for other purposes is a complicated and expensive process, and research activities funded by organizations such as The U.S. Department of Energy (DOE) are investigating innovative treatment techniques. These investments by DOE support the Water Security Grand Challenge, a White House-initiated, DOE-led framework that advances transformational technology to meet the global need for safe, secure, and affordable water.
Research on produced water treatment has also heightened at higher-ed institutions across the country, including The University of Texas at Austin, to arrive at the best solutions. One of these techniques includes desalination of produced water for municipal and irrigation reuse. However, desalination is currently a costly procedure—an issue that has contributed to the controversy over this treatment solution. With innovation and technological advancements, treatment and re-use techniques for produced water may become more affordable, reducing the risk of water scarcity in the future.
The Society of Petroleum Engineers2Society of Petroleum Engineers. (n.d.). challenges-in-reusing-produced-water. Retrieved July 11, 2021, from https://www.spe.org/en/industry/challenges-in-reusing-produced-water/. highlights several methods that currently can be used to treat produced water. Removal of contaminants such as radioactive materials, heavy metals, and dissolved organic compounds require various techniques, such as:
- Adsorption: Use of activated carbon or other material to remove organic compounds
- Sand filtration: Filtration technique used to extract and remove heavy metals
- Reverse osmosis: Filtration through membranes to remove organic compounds, heavy metals, and other contaminants
- Thermal desalination: required to treat water with TDS exceeding that of seawater
The above techniques occur throughout three main stages, but specifically during the main treatment stage, of produced water treatment:3Society of Petroleum Engineers. (n.d.). challenges-in-reusing-produced-water. Retrieved July 11, 2021, from https://www.spe.org/en/industry/challenges-in-reusing-produced-water/.
- Pre-treatment stage: Initial removal
- Main treatment stage: Secondary removal and treatment techniques deployed such as reverse osmosis and thermal desalination
- Polishing treatment stage: Final removal