Development of Packed-Tower Air Strippers for Trichloroethylene Removal at Wurtsmith Air Force Base, Michigan

摘要

Packed-tower air stripping was researched and developed to treat trichloroethylene (TCE)-contaminated groundwater at Wurtsmith Air Force Base (Oscoda), Michigan. A leaking underground storage tank has caused a 1000 meters (3200 feet) long, 500 meters (1600 feet) wide, and 18 meters (60 feet) deep plume, with a maximum concentration approaching 10,000 ppb. While activated carbon could have produced treated water with an effluent TCE concentration below Michigan's 1.5 ppb discharge standard, the projected $1.5 million capital cost and the annual $400,000 operating and maintenance costs were prohibitive. At the request of HQ Strategic Air Command, the Engineering and Services Center investigated alternate groundwater treatment techniques. Laboratory studies were performed to determine removal efficiencies and mass transfer coefficients for TCE on 16 mm (5/8-inch) (and 25 mm (1-inch)) polypropylene Pall rings at various liquid and air flows, and at temperatures ranging from 10-30 C (50-86 F). Performance equations and removal efficiencies were combined to provide relationships for determining the required packing volume. Based on these studies, twin packed-tower air strippers were built onsite at Wurtsmith AFB. The strippers were performance-tested from May 1982 to May 1983, with removal efficiencies averaging better than 99.9 percent.