NMSU Student Studies the Recovery of Rare Earth Elements and Potable Water from Produced Water

By Marcus Gay, NM WRRI Student Program Coordinator

New Mexico is facing water challenges due to increasing water demand and chronic drought. Water researchers and managers are constantly looking for new ideas about freshwater resources. Produced water— a fluid that is an incidental byproduct from drilling for or the production of oil and gas —is the largest waste stream generated during oil and gas production. A potential solution to address some of New Mexico’s water challenges is to develop low-cost, energy-efficient systems that generate clean water from produced water sources.

In some New Mexico produced water sources, rare earth elements such as lanthanum (La), neodymium (Nd), and europium (Eu) have been detected. If these rare earth elements could be recovered in an efficient way, there is a high potential for earnings that could subsidize the cost of generating clean potable water from produced water sources.

In response to these challenges, Lin Chen, a PhD candidate in New Mexico State University’s Department of Civil Engineering, has been working on a project that provides an environmentally friendly and economically attractive solution to water scarcity issues. Under the guidance of his faculty advisors, Dr. Frank Ramos and Dr. Pei Xu, the project aims to produce clean water while recovering rare earth elements in the process. NM WRRI has awarded Lin a Student Water Research Grant for a project entitled, Recovery of Rare Earth Elements and Potable Water from Produced Water, which will develop an energy-efficient and low-cost treatment system to produce clean water while optimizing the extraction of rare earth elements from produced water collected from the Permian Basin.

The first task of the project is clean water production which includes the development of bench-scale high-performance solar driven distillation system: a single-basin, single-slope solar still used to generate clean water with total dissolved solids concentration no greater than 500 mg/L. As the water evaporates in the solar still, rare earth elements will begin to concentrate, which will facilitate separation and extraction in the next step. The second task of the project is the multi-stage process to recover rare earth elements. This task includes building a bench-scale system and conducting laboratory experiments under controlled conditions for rare earth element separation and extraction.

The project aims to generate clean water from produced water that meets drinking water standards, and minimal recovery of 70 percent of rare earth elements La, Nd, and Eu using the multi-stage process for extraction and separation. According to Lin, the study provides a promising sustainable process for producing clean water, reducing produced water disposal, and recovering rare earth elements with significant economic and environmental benefits. As Lin explains, “potable water and resource recovery from produced water is vitally important to subsidizing the treatment cost of produced water and providing a method to reuse a large amount of produced water. This also mitigates the risk of discharging produced water and contaminating groundwater via deep-well injection.”

Lin presented this project at the 65th Annual New Mexico Water Conference in October 2020. Originally from China, Lin earned his bachelor’s and master’s degree in Environmental Engineering working on the biological removal of nitrogen from surface water. Lin hopes to complete his PhD in Environmental Engineering this year, and plans to become a postdoctoral researcher after graduation.