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Demonstration of Pilot-Scale Prevaporation Systems for Volatile Organic Compound Removal from a Surfactant Enhanced Aquifer Remediation Fluid. I. Spiral Wound Membrane Modules
Citation:
Alvarez*, F R., L M. Vane*, AND L Hitchens*. Demonstration of Pilot-Scale Prevaporation Systems for Volatile Organic Compound Removal from a Surfactant Enhanced Aquifer Remediation Fluid. I. Spiral Wound Membrane Modules. Environmental Progress & Sustainable Energy 20(1):53-63, (2001).
Description:
During the summer of 1996, a pilot-scale demonstration of a surfactant enhanced aquifer remediation (SEAR) process for removal of dense non-aqueous phase liquids (DNAPLs) from soils was conducted at Hill Air Force Base in Layton, Utah. Five thousand gallons of the extracted DNAPL-surfactant solution were transported to Cincinnati, Ohio to be processed at the USEPA's Test & Evaluation Facility. A pervaporation pilot-scale unit equipped with spiral wound modules was used to process this waste streams. The main DNAPLs in the extracted SEAR fluid were trichloroethylene (TCE) at 3,000 mg/L, 1,1,1-trichloroethane (TCA) at 450 mg/L, and tetrachloroethylene (PCE) at 400 mg/L. The solution also contained 2.5 wt% anionic surfactant, 1.5 wt% isopropyl alcohol, and 1.0 wt% salt. This demonstration highlighted complications posed by secondary contaminants to this application of spiral wound modules. At this site, the chlorinated compounds were used as degreasing solvents for parts cleaning operations. As a result, the DNAPL contained a small amount of non-volatile oils which, by themselves, were not soluble in the surfactant solution although they were soluble when TCE was present. The deposition of this oil in the pervaporation modules was prevented by the addition of a non-ionic surfactant, Triton X-100, to the feed stream. Thirteen runs were performed with commercially available spiral wound pervaporation modules at various flow rates and temperatures. Single-pass VOC removal ranged from 50% to 98% depending on the VOC and the conditions of the experiment. In all cases, TCE removal was almost identical to TCA removal and both were easier to remove than PCE. Most of the runs during the demonstration lasted between 8 and 9 hours. A single 28 hour run was performed to see how the performance of the unit would be affected during an extended period of operation. After 28 hours, the percentage removal of VOCs was similar to that obtained during the shorter runs.