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ORNL PILOT PLANT HELPS EVALUATE AND IMPROVE WASTEWATER TREATMENT METHODS

 OAK RIDGE, Tenn., Jan. 28 /PRNewswire/ -- In recent years, the Department of Energy (DOE) has strengthened its efforts to clean up hazardous waste resulting from past operations and to greatly reduce the amount of new waste produced at its facilities nationwide.
 As part of the efforts, chemical engineers in Oak Ridge have designed a unique facility to monitor and evaluate methods of treating wastewater. The work is being funded by DOE's Office of Environmental Restoration and Waste Management.
 Called the Wastewater Treatment Test Facility (WTTF), it was designed to be a scaled-down, combined version of two elaborate wastewater treatment systems at DOE's Oak Ridge National Laboratory (ORNL) -- the Process Waste Treatment Plant and the Nonradiological Wastewater Treatment Plant.
 "It was made to simulate, on a small scale, the operations at both plants," said Cliff Brown, a section head in ORNL's Chemical Technology Division.
 ORNL researchers use the mini-plant to test certain wastewater samples before full-scale treatment operations begin. "It gives an indication of how effective a full-scale plant will be at treating certain liquid wastes expected to come from present and future cleanup activities," Brown explained, adding that it also reveals ways to improve treatment processes.
 The test facility is a rectangular trailer, 48 feet long and sided with aluminum. Sitting idle in a paved lot, it looks like a trailer from an eighteen-wheeler. But inside is a high-tech laboratory in which small stainless-steel tanks and tall plastic columns filled with carbon chips and purifying resins treat samples of wastewater to remove contaminants.
 The first phase of treatment in the laboratory simulates the Process Waste Treatment Plant. In the small stainless-steel tanks, calcium, magnesium and other minerals are separated out to soften the water, and any radioactive contaminants, such as cesium-137 and strontium-90, are removed by a purifying resin.
 Then begins a second round of purification, imitating operations at the Nonradiological Wastewater Treatment Plant.
 In a process called air stripping, wastewater is pumped to the top of clear, plastic columns and allowed to trickle down through about ten feet of packing material that resembles chips of seashells. This increases the water's surface area, making it easier for organics, such as toluene and xylene, to move out of the water and into a flow of air that is continually pumped up through the columns, which are floor-to- ceiling tall. The air, which carries and disperses the chemicals in a more environmentally safe manner than does water, is then siphoned away through an exhaust system. (If large amounts of contaminants were being stripped, the air from the columns would undergo additional treatment before being discharged to the outside.) To further ensure purification, the water is filtered again, this time through a column filled with chips of activated carbon. This removes large organic molecules and any mercury that may be present.
 The step-by-step treatment precisely mimics the operations in the two full-scale facilities. "But because of its operating scale, the pilot-plant testing is much less expensive and greatly reduces risks to the environment," Brown said.
 The wastewater most recently tested at the pilot plant came from ORNL's Solid Waste Storage Area number six (SWSA-6), which is scheduled for closure activities by Martin Marietta Energy System's Environmental Restoration organization. During closure, full-scale wastewater treatment will be necessary, and plans are to use the Process and Nonradiological Plants for that purpose.
 "The pilot plant worked just great in testing the SWSA-6 samples," said Tim Kent, principal investigator at the test facility. He said the tests answered one of the most important questions about the closure of the storage area: whether the two full-scale plants could treat the wastewater without producing mixed waste, a combination of wastes that are regulated individually as "hazardous" or "radioactive."
 "Mixed waste poses the biggest challenge, both from a regulatory and a disposal standpoint," Kent said. "We were really pleased to find that treating the SWSA-6 wastewater with our existing methods did not produce any mixed waste."
 The new test facility is transportable and has a system design that can be altered for various studies without a major expenditure, which could make it useful to other sites involved with waste treatment. It will be used extensively in the future to evaluate treatment of other cleanup-related waste streams and to perform process improvement studies for the ORNL liquid-waste treatment plants.
 Currently, the system is being altered for process improvement studies at the Process Wastewater Treatment Plant.
 At ORNL, improving the full-scale treatment processes through pilot plant experiments will mean continuous improvement in the quality of water treated and put back into the environment. Additionally, because water that is treated experimentally is recycled back to the full-scale plants, the process improvement studies can be performed with no risk to aquatic life or surrounding communities.
 ORNL is one of five energy-related research and production facilities managed by Martin Marietta Energy Systems for the Department of Energy.
 -0- 1/28/93
 EDITOR'S NOTE: Photo and caption are available upon request by calling 615-574-4160 and asking for ORNL Pilot Plant photo.
 /CONTACT: L. Darryl Armstrong, Public Affairs Department, Oak Ridge National Laboratory, Martin Marietta Energy Systems, Inc., 615-574-4160/
 (ML)


CO: Oak Ridge National Laboratory, Martin Marietta Energy Systems, Inc. ST: Tennessee IN: CHM SU: PDT

CM -- CH001 -- 0048 01/28/93 08:32 EST
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Date:Jan 28, 1993
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