Guidelines based on life cycle assessment for solvent selection during the process design and evaluation of treatment alternatives†
The aim of this paper is to develop guidelines in order to assist in decision making with respect to treatment options of waste solvents, and more importantly for the choice of solvent in the design of the process a priori, from an environmental point of view based on the composition of a mixture. Life cycle assessment (LCA) was used to evaluate two treatment alternatives: continuous distillation and incineration. The software Ecosolvent® v.1.0.1 was used to perform the LCA, considering two scenarios (the best and worst scenarios) and five environmental indicators: Eco-indicator 99, UBP-97, global warming potential, cumulative energy demand and CO2-balance. From the results, it can be concluded that the environmental impact originating from the production of the solvents is the main issue to consider for the selection of distillation or incineration as the treatment method during the process design. In general, those solvents with a low impact during their production stage were found to be candidates for incineration. Moreover, those compounds that yield a great environmental burden during the production step should be always recovered in order to minimize the total impact. A series of charts is presented as guidelines to select the most environmentally favorable alternative for mixtures of solvents, and to select which solvent to use considering the environmental effects that are produced. Regarding the information given by the different indicators, it was observed that all the studied indicators lead to the same conclusions for the evaluated mixtures with some exceptions for UBP-97.