(678c) Green Engineering Analysis of a Multi-Use Solvent Recovery System for Small Volume Waste Steams in the Pharmaceutical Industry

A green engineering study has been conducted to analyze the economic viability and quantify the environmental benefits of a small solvent recovery system as an alternative to incineration for addressing smaller volume waste streams.

Solvent recovery is a routine practice in the pharmaceutical industry when it is technically and economically viable for the particularly waste stream. Capital investment in the required piping, tank farms and recovery equipment is more easily justified when dealing with large volumes, high cost solvents and high equipment utilization rates, and when solvents from multiple products can be pooled together ? i.e. the don't require segregation by product. The use of recovered solvents, and pooling of solvents, must be appropriately qualified to assure product quality and avoid cross contamination. Economic justification to recover small-volume, ?non-poolable?, and intermittently generated waste streams remains challenging, but a potential recovery opportunity.

A case study was performed on the waste streams being generated at an API synthesis building at the Pfizer Kalamazoo, Michigan plant. The goal was to investigate those streams that could be most easily recovered with simple phase or equilibrium-based separations. As a first step in that analysis, the recovery of acetonitrile from a waste stream in the selamectin synthesis was considered. Selamectin is the active ingredient in the veterinary drug Revolution®. This stream was initially chosen due to the relative high cost (and value) of acetonitrile and the ability to separate acetonitrile from the acetone impurity.

A small-scale distillation solvent recovery system was designed and the proposed operation compared with the current waste disposal practice. The case study estimates the environmental benefits, using life cycle assessment tools, and the financial metrics for the proposed improvement. To increase the economic feasibility of a capital investment and improve the environmental footprint further, the proposed design was evaluated for use with the other waste streams in the facility. The simulation included isopropanol recovery from the manufacture of nelfinavir, an antiretroviral drug (Viracept®); and toluene recovery from hydrocortisone manufacture.

An overall environmental analysis was performed evaluating the impact of utilities (and resulting emissions) needed to operate the distillation unit versus the savings from not having to manufacture the virgin solvent and incinerate it. These were then analyzed through a cost/benefit analysis.