Recycling and recovery of solvents is an important downstream issue that should be considered. Solvent recovery can have a positive effect on the environmental impact and hence the metrics of a given process. Studies have been carried out to determine whether solvent recovery is viable depending upon factors such as the energy required to achieve this. ETH Zurich has also developed an LCA based tool that allows the environmental impact of waste-solvent treatment to be quantified.
The incineration of spent solvent as opposed to their recovery has been shown to considerably increase the life cycle impacts. However this depends on the complexity of the production of the solvent itself and its boiling point, for solvents such as diethyl ether incineration is a more preferable option than distillation in terms of Total Cumulative Energy Demand (CED).
Where solvent recovery is deemed to be uneconomical, other options include down-cycling the solvent for example for heat recovery or use in other industrial applications.
Other approaches could include solvent ‘leasing’ whereby used solvent is collected by supplier and cleaned up for reuse.