Technology Transfer

Hazardous Waste Recycled to Commercial Fertilizer

A JOINT EFFORT BETWEEN KENNEDY SPACE Center and I-NET Inc. (the engineering support contractor, now held by Dynacs Engineering Co.) has resulted in an innovative control system and process that recovers and converts unused rocket propellant oxidizer into a useful fertilizer. The Improved Nitrogen Oxide (NO_x) Scrubber is projected to save Kennedy about $80,000 per year in waste disposal and fertilizer costs. The scrubber also provides safety and environmental improvements by reducing workers' risk of exposure to toxic NO_x emissions by a factor of 10 to 200.

Developed from a concept by Kennedy engineer Dr. Dale Lueck and designed by Dr. Clyde Parrish of I-NET, the innovation eliminates Kennedy's second largest waste stream and associated waste disposal costs. "The resulting fertilizer replaces 10 percent of the potassium nitrate fertilizer purchased at Kennedy and does not add significantly to the raw material costs," Parrish said, adding that the "overall cost savings at Kennedy is approximately $80,000 per year."

Kennedy plans to install the system at several scrubbers. The control system could also be used at Vandenberg Air Force Base in California, White Sands Test Facility in New Mexico, Cape Canaveral Air Station in Florida, Titan Launch Complex 40 or any location where the quantity of oxidizer requires a scrubber. Any commercial industries in which NO_x is released, such as metal finishing operations, could also use the technology. NASA has a pending patent application for this technology.

A Space Shuttle steering rocket uses nitrogen tetroxide as its propellant. When the toxic oxidizer (nitrogen tetroxide) is transferred from storage tanks into rockets, or vice versa, the nitrogen dioxide vapor is captured in a device called a scrubber to prevent it from venting to the air.

A control system was developed to convert the hazardous NO_x scrubber liquor to a useful, beneficial and marketable fertilizer. The chemical process captures nitrogen tetroxide in water, in which hydrogen peroxide oxidizes the resulting nitrous acid into nitric acid. The nitric acid is neutralized with potassium hydroxide to form the product potassium nitrate. No commercial controller exists that can provide hydrogen peroxide in the concentration range of 0.5 to 5.0 percent.

NASA needed to design and build a controller that could handle the particulate residues known to exist in the oxidizer and distinguish the difference between hydrogen peroxide and the oxides of nitrogen. The controller uses the oxidation of hydrogen peroxide with sodium hypochlorite (bleach) to produce oxygen, then measures the resulting pressure. The pressure is directly proportional to the hydrogen peroxide concentration, and the controller monitors the pressure and adds hydrogen peroxide as required to maintain the required pressure. Other requirements were to integrate the pH controller, level controller and remote control of the system from the operations control panel.

For more information, contact Tom Gould at Kennedy Space Center.
Call: 407/867-6238, Fax: 407/867-2050, E-mail: Thomas.Gould-1@kmail.ksc. nasa.gov
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