New techniques for solvent recovery and elimination of wastewater emissions during vacuum process operations

Abstract

AbstractThe pharmaceutical and chemical process industries are concerned with controlling volatile organic compound (VOC) emissions for several reasons: to meet environmental regulations, for increased worker safety, and to minimize product losses. Various methods can be used including flaring and carbon adsorption. These techniques are end‐of‐the‐pipe solutions and are not integral with the process operation itself.An improved technique for the recovery of solvents during reaction, distillation, evaporation, drying, filtration, mixing, and other vacuum operations is the APO‐VAC vacuum/gas compressor system. The skid‐mounted, engineered package is based upon a single stage liquid ring vacuum pump. The system allows for the recovery and reuse of clean solvent with minimum air emissions and zero liquid emissions. VOC and biological oxygen demand (BOD) regulations are met by this technology.The paper reviews the technical details of the system and presents test results and on‐site operational data. Specific case histories involving methylene chloride recovery and acid/toxic gas neutralizations are also included.In the chemical processing industry (CPI) the generation of vacuum is a necessity. Many chemical processes take place more easily, more quickly and more efficiently under vacuum than under atmospheric pressure, thus allowing better product quality at lower production cost. If it is a “wet” process involving the use of solvents then solvent recovery becomes an important consideration because of cost savings associated with its recovery as well as environmental benefits.These objectives have stimulated the development of the APOVAC system concept which is based on the principle of closed loops or circuits. Since its development, the APOVAC system has enhanced today's chemical process technology through solvent recovery and recycling, elimination of wastewater effluent, and reduction of gas emissions thus contributing to a technically efficient and environmentally acceptable operation.