A HYBRID OF VAPOR PERMEATION AND MEMBRANE-BASED ABSORPTION-STRIPPING FOR VOC REMOVAL AND RECOVERY FROM GASEOUS EMISSIONS

A hybrid process that combines a vapor permeation process with a recen tly developed membrane-based absorption and stripping process using an inert essentially nonvolatile absorbent oil is described here for a v ery high degree of removal of volatile organic compounds (VOCs) from v ented gas streams. The combined and continuous process of this study u ses the same utility, a vacuum pump, and achieves a very high level of VOC removal, for example, 99.57-99.97% from a N-2 feed stream contain ing 6,000 ppmv of methylene chloride. The performance is illustrated h ere using hollow fiber membrane modules of two kinds: microporous poly propylene hollow fibers having an ultrathin nonporous silicone coating used for vapor permeation first and then later for regenerating the V OC-loaded absorbent by VOC stripping via vacuum; microporous polypropy lene hollow fibers without any nonporous coating for nondispersive abs orption of VOCs from the waste gas stream.