Waste-Solvent Management as an Element of Green Chemistry: A Comprehensive Study on the Swiss Chemical Industry

Abstract

The treatment of organic waste solvents is an important issue in the chemical industry as large amounts accrue annually. As all treatment options are associated with specific environmental impacts, a sound management of waste solvents can therefore lead to large ecological benefits. The goal of this work was therefore to identify opportunities and requirements for an environmentally sound waste-solvent management. To this end, a survey was carried out together with the Swiss chemical industry. The results show that only a few technologies are used on a grand scale, such as incineration and distillation for solvent recovery. But waste-solvent management is strongly influenced by boundary conditions such as costs, logistics, legislation and guidelines, storage capacity, safety considerations, and the existing technologies on the production site. Thus, we identified that the best opportunity to optimize waste-solvent management would be in an early stage of process design, for instance, before scale-up for the launching of the production or when production campaigns change. Two actual case studies from the chemical industry show how environmentally sound waste-solvent management can be integrated in the planning of a chemical company and lead to ecological benefits. In the first case study a company investigates different routes of waste-solvent treatment for waste streams which are treated outside the plant by third parties. In the second case study different options for the treatment of a dimethoxy ethane mixture are assessed, taking into account environmental impacts by a life-cycle perspective.