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Posted 1/1/1993

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By Richard Broussard
Release No. 93-1


Hanover--Dedication and startup of a new temporary water treatment plant for the removal of trichloroethylene (TCE) from the Cold Regions Research and Engineering Laboratory's industrial water supply is scheduled for early February at a site behind the Main Laboratory building. CRREL is located at 72 Lyme Rd (Rt. 10) in Hanover.

This $300,000 interim treatment plant will continue in operation until a permanent plant is completed in January 1994. Construction of the temporary and permanent treatment plants is a rememdial action under the Department of Defense's Installation Restoration Program put in place to clean up TCE discovered in CRREL's groundwater two years ago.

The temporary facility that is being dedicated is termed a "packed tower" ground water treatment plant. It is designed to strip volatile organic gases out of liquid (i.e., TCE out of CRREL's groundwater).
How the sytem works: First, water-bearing TCE is introduced at the top of the tower, which is packed with plastic media (small, irregular-surfaced balls about the size of ping pong balls) that maximize the surface area of water. Then air is blown up from the bottom. This sets up a water/air counter-current flow which optimizes conditions for vo litization or evaporation. TCE is forced out of the water and into the air. 11,e water is now clean and can be used in CRREL's refrigeration systems and then discharged into the river. 11le air passes from the packed tower to a granular-activated carbon unit (GAC). The GAC has many absorption surfaces where the TCE will be absorbed out of the air by the carbon.

The air is finally clean and released. The GAC can be used for a long time until fully saturated; it is then regenerated by heating until the TCE is destroyed.

The permanent plant will cost approximately $1.6 million ($240,000 will have been invested in equipment for the temporary plant) and will have an additional process called a "green sand filter" to remove iron and manganese that are common in area groundwater.