Demonstration of pilot-scale pervaporation systems for volatile organic compound removal from a surfactant enhanced aquifer remediation fluid II: Hollow fiber membrane modules

Abstract

Pilot-scale demonstration of pervaporation-based removal of volatile organic compounds from a surfactant enhanced aquifer remediation (SEAR) fluid has been conducted at U.S. EPA's Test & Evaluation Facility using hollow fiber membrane modules. The membranes consisted of microporous hydrophobic polypropylene fibers having a thin plasmapolymerized silicone layer on the outside surface. The SEAR fluid was allowed to flow through the fiber bores at 35-45°C, while vacuum was pulled on the shell side. The SEAR fluid was obtained from a pilot-scale demonstration at Hill Air Force Base, Layton, Utah, and contained trichloroethylene (TCE) at 3,000 mg/L, 1,1,1-trichloroethane (TCA) at 450 mg/L and tetrachloroethylene (PCE) at 400 mg/L along with 2.5 wt% anionic surfactant, 1.5 wt% isopropyl alcohol, 1 wt% salt and a small amount of nonvolatile oil/grease. The hollow fiber modules were run at flow rates of 0.25-1 gpm for a period of 8-10 hours every day for a total of six weeks along with a continuous 40-hour run using the SEAR fluid. The modules were never washed with any fluid. The performance of the hollow fiber modules was stable and satisfactory vis-à-vis VOC removal and pressure drop considerations.