UPGRADING THE PERFORMANCE OF GROUNDWATER VOC AIR STRIPPERS

Rocketdyne's Santa Susana Field Laboratory has been treating groundwat er to remove chlorinated solvents since 1987. Six air stripping treatm ent installations, using vapor-phase carbon to control air emissions, have consistently met effluent quality standards over nine years of op eration. In 1995, Rocketdyne embarked on an inspection and maintenance program to thoroughly check tower equipment and packing condition and to improve treatment efficiency using new packing technology now avai lable. Baseline removal efficiency measurements were made on one large -capacity air stripper, which was then shut down for inspection. The o riginal random packing was found to be fouled, and had settled too far below the level of the spray nozzle. The packing was removed, and rep laced with a newer, high-efficiency packing. As a result, single-stage removal efficiency for trichloroethylene increased from 98.5% to >99. 6%. Aside from demonstrating the improvement attainable by upgrading t he packing media, Rocketdyne's maintenance program also highlighted th e critical importance of proper liquid distribution. At one point, the refurbished air stripper was overpacked, resulting in concentration o f the water spray near the center of the packed section. The liquid di stribution was found to remain grossly nonuniform even after the water had trickled down over 8.2 meters of packing in a 91-cm diameter colu mn.