In the arid expanses of the Ordos Basin, where coal mining is both a lifeline and a threat to fragile ecosystems, a breakthrough is quietly reshaping how the energy sector manages one of its most persistent challenges: highly mineralized mine water. Researchers led by Xin LI from the School of Resources and Geosciences at China University of Mining and Technology have developed a cost-effective, sustainable solution that could redefine water management in western China’s coalfields.
The problem is both economic and environmental. Traditional membrane-based treatment of high-TDS (total dissolved solids) mine water is prohibitively expensive in regions like Inner Mongolia and Shaanxi, where mineralization levels often exceed 10,000 mg/L. Meanwhile, unchecked reinjection risks contaminating groundwater, a critical but dwindling resource in an already water-stressed region.
LI and his team turned to an unconventional yet elegant strategy: deep storage and reinjection of untreated or minimally treated mine water into the Liujiagou Formation sandstone, a geological layer buried deep beneath the surface. “We’re not just storing water—we’re using the earth itself as a natural filtration and containment system,” LI explained. “This approach leverages the natural low permeability and porosity of the sandstone to safely isolate mineralized water while preserving surface water quality.”
Their research, published in *Meitan xuebao* (Journal of China Coal Society), began with a rigorous geological screening process. By analyzing multiple strata, they identified the Liujiagou Formation as the optimal reinjection target due to its favorable hydrogeological properties and isolation from potable aquifers. The team then mapped the formation’s internal structure in unprecedented detail, dividing it into seven distinct layers using CT scanning and seepage experiments.
“What surprised us was the internal heterogeneity,” said LI. “While the entire formation is classified as a low-permeability aquifer, certain layers—especially the third and fifth—showed unexpectedly high static storage capacity and permeability. That means we can target injection zones with precision, maximizing storage efficiency.”
To validate the concept, the team built a 3D hydrogeological model using GMS software, simulating seven decades of continuous reinjection from a single well. The results were striking: after 700 days, the system could store 1.8054 million cubic meters of water, with a maximum hydraulic influence radius of 466.1 meters—without compromising groundwater safety.
But the real innovation lies in the operational model. Instead of relying solely on energy-intensive membrane treatment, the team proposes a hybrid system: “micro-treatment on the surface, deep reinjection underground.” This hybrid approach reduces costs by approximately 40% compared to conventional methods, making sustainable mine water management financially viable even in low-margin coal operations.
The technology is already gaining traction. Successful pilot applications have been reported in mines like Hujierte and Nalinhe in the Ordos Basin, where coordinated exploitation of coal and water resources is now possible under China’s stringent “zero discharge” policy for mine water.
For the energy sector, this research signals a paradigm shift. It offers a scalable, cost-competitive pathway to comply with environmental regulations while unlocking value from previously untreatable water. As water scarcity tightens its grip on arid mining regions, technologies that enable resource recovery without prohibitive costs will define the next generation of sustainable mining.
In a landscape where every drop counts, LI’s work suggests that the solution may not lie in purifying water at all costs, but in using the earth’s own architecture to store, isolate, and eventually—perhaps—recover it.