CARBON ADSORPTION/MEMBRANE REGENERATION HYBRID SYSTEM

CURRENT AND FUTURE LEGISLATION WILL REQUIRE U.S. INDUSTRY TO TREAT MANY ORGANIC SOLVENT-CONTAINING AIR STREAMS NOW BEING DISCHARGED TO THE ATMOSPHERE. STREAMS OF THIS TYPE ARE PRODUCED BY PROCESSES SUCH AS PAINT REMOVAL AND METAL DEGREASING, AND IN PAINTING AND COATING OPERATIONS. MEMBRANE TECHNOLOGY AND RESEARCH (MTR) HAS DEVELOPED A MEMBRANE VAPOR RECOVERY PROCESS THAT IS ABLE TO REMOVE SOLVENT VAPORS FROM EFFLUENT AIR STREAMS, AND TO RECOVER A CONDENSED LIQUID SUITABLE FOR REUSE. HOWEVER, THE MEMBRANE SEPARATION TECHNOLOGY IS NOT ECONOMICALLY VIABLE FOR STREAMS CONTAINING LESS THAT 0.5% SOLVENT VAPOR. CARBON ADSORPTION IS USUALLY USED TO TREAT THESE STREAMS. CARBON ADSORPTION IS A RELATIVELY COST EFFECTIVE AND EFFICIENT PROCESS, AND IS PARTICULARLY SUITED TO LOW-CONCENTRATION WASTE STREAMS. HOWEVER, REGENERATION PROCEDURES USE STEAM AND PRODUCE A FINAL WASTE STREAM CONTAINING 5-10% SOLVENT IN WATER. THIS STREAM IS TOO DILUTE TO BE EASILY REUSED AND DISPOSAL IS USUALLY AS A HAZARDOUS WASTE. THE PROCESS MTR PROPOSES TO DEVELOP USES A MEMBRANE VAPOR SEPARATION SYSTEM AS AN INNOVATIVE METHOD OF REGENERATING THE CARBON BED USING HOT NITROGEN, WHICH CAN BE RECYCLED, AND ALLOWING RECOVERY OF THE SOLVENT AS A PURE PRODUCT. SECONDARY WASTE STREAMS ARE ELIMINATED. IN THE PROPOSED PROCESS BOTH TECHNOLOGIES OPERATE IN THEIR MOST FAVORABLE RANGE. THE ECONOMICS OF THE PROCESS APPEAR TO BE ATTRACTIVE.