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Recycled crab shells treat acid mine drainage

Mining for coal or precious metals can result in the release of sulfuric acid and dangerous metals into downstream waters, often making them unsuitable for supporting life. However, researchers at Penn State University have demonstrated that recycled crab shells containing chitin can significantly improve the treatment of acid mine drainage.

One of the most abundant natural materials in the world, chitin is used to make paper, fabrics, weight-loss pills and joint care supplements, among other products. In crustaceans like crab and shrimp, chitin combines with calcium carbonate, the same chemical in limestone. Results from the Penn State research indicate that this combination may be extremely effective at cleaning acid mine drainage.

The drainage from abandoned mines contaminates tens of thousands of miles of streams in the U.S. alone, and the majority goes untreated. The development of new methods to efficiently clean acidic, metal-laden water is sorely needed to restore these valuable water resources. 

Encouraged by the positive results of initial laboratory tests, the researchers are now extending the application of crab shells to "high risk" discharges where other treatment remedies have failed, like the Klondike-1 (KL-1) site in Cambria County, Pa. In the laboratory, researchers tested the KL-1 water with different crab shell loadings to find the most cost-effective solution. Building on preliminary designs developed by students in a new "Field Methods for Remediation Design" class supported by this project, the research team is now field-testing crab shell substrates at the KL-1 site. This pilot test is a necessary step towards validating the technology for full-scale application. 

Images (1 of )

  • acid mine drainage seeps into water in cambria, pennsylvania
  • a researcher monitors different materials to treat acid mine drainage
  • pilot reactors at an acid mine drainage site
Acid mine drainage seeps into waters in Cambria County, Pennsylvania.
Rachel Brennan, Penn State
A researcher monitors several substrate combinations to treat mine drainage.
Sara Brennen, Penn State
Pilot reactors at the Klondike-1 mine drainage site.
Rachel Brennan, Penn State

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