Diagnosing chlorine industrial metabolism by evaluating the potential of chlorine recovery from polyvinyl chloride wastes—A case study in Japan

Abstract

A case study was conducted in Japan in 2012 using material flow analysis (MFA) over a series of processes (salt import, chlor-alkali industry, polyvinyl chloride (PVC) production, PVC waste management, and advanced chlorine recovery process) that are steps in the chlorine life cycle, to reveal the potential of Cl recovery from PVC wastes. This study indicated that 335kt of the Cl exist in PVC waste are targeted for Cl recovery because almost all the Cl fraction in this waste is undesired during its recycling and disposal. Cl recovery potential was estimated to be 293 kt, which corresponds to 40% of Cl demand in PVC resin production, 9% of Cl2 production in the chlor-alkali industry, and 7% of the imported salt. Advanced chlorine recovery process from PVC waste makes it possible to dechlorinate PVC and to recover Cl as a salt (NaCl). This process reduces risks accompanying Cl removal during PVC waste treatment, and it improves the value of PVC waste as a hydrocarbon source. Recovered NaCl can replace part of the imported salt in the chlor-alkali industry. This will reduce salt supply problems that occur because salt is produced in a limited number of countries. This advanced process will link the PVC industry with the chlor-alkali industry in what can be called the “chlorine circulation system.” It is an efficient system that can create a win–win situation for both industries while reducing the environmental burdens.