Process For Converting Nitrates To Nitrogen Gas

Now researchers at the Department of Energy's Los Alamos National Laboratory have developed an inexpensive, potentially revolutionary process for converting solid and liquid nitrate wastes into harmless nitrogen gas. The inventors will demonstrate the new process to potential industrial partners in workshops scheduled for February.

Nitrates are essentially salts or compounds of nitric acid. They can cause excessive biological activity, vegetation growth and precipitation of organic residue once they come into contact with bodies of water such as lakes. Excessive nitrate concentrations can transform healthy bodies of water into decaying marshes. If consumed in sufficient quantities, nitrates can cause harm to humans, especially infants. Studies have shown that nitrates in sufficient amounts can cause a disease commonly called Blue Baby Syndrome, a congenital heart disease characterized by such signs as bluish discoloration of the skin, breathing difficulty and heart murmur.

Several methods currently are used worldwide to destroy or remove nitrate wastes, such as reverse osmosis, evaporation and thermal or biological destruction. But they are often energy-intensive --- thus expensive to use -- and may still leave harmful waste residues. The new nonthermal, nonbiological process developed by researchers Jacek Dziewinski, Joel Anderson and Stas Marczak of Los Alamos' Environmental

Systems and Waste Characterization Group utilizes a unique transition metal/acid mixture that strips oxygen atoms from nitrates, converting them first to nitrites and ultimately to nitrogen gas. The gas can then either be recaptured or released into the atmosphere.

"One of the beauties about this new process is its simplicity and ease of use," said Dziewinski.

Under its current test configuration, nitrate-laced wastewater is pumped into a chamber filled with the metal/acid catalysts. As the

wastewater flows through the chamber, the metal catalyst strips away one oxygen atom from each nitrate, while the acid catalyst strips away the remaining two oxygen atoms. The end result is nitrate-free wastewater. Solid nitrate salts or heterogeneous solids containing nitrates can be treated with the same process simply by mixing them with water.

During the stripping process, the metal dissolves into a solution that's mixed with the wastewater. That mixture is pumped into an electrolytic cell, where the metal ions are converted back to their original metallic form, then pumped back into the chamber reactor tank. "As a result, we can reuse the metal countless times for future stripping, so the new process is very cost-effective," explained Dziewinski. "The process is safe, and the equipment is inexpensive compared to the other technologies because it runs at ambient temperatures and pressures."

Dziewinski also said Los Alamos is interested in implementing the technology on a large scale. The Laboratory currently is pilot testing the process at Los Alamos' Liquid Radioactive Waste Treatment Facility.

Los Alamos produces nitrate waste daily as part of normal operations.

WORKSHOPS FOR INDUSTRIAL PARTNERS ANNOUNCED

Those interested in learning more about the new process should attend one of the Nitrate Conversion Commercialization Workshops scheduled for Feb. 1, 2, 8 and 9 in Los Alamos' Civilian and Industrial Technology Program Office. Each workshop is limited to 30 registrants and the fee is $75, which covers food, transportation, workshop materials and a one-on-one session with technical staff at Los Alamos for those interested in licensing the technology.

For more information or to register for a workshop, contact Laura Barber or Andrea Pistone at 505-665-9090. Or write to ljbb@lanl.gov or apistone@lanl.gov by electronic mail.

Los Alamos National Laboratory is managed by the University of California for the U.S. Department of Energy.

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