Framework for evaluating the "greenness" of chemical processes: case studies for a novel VOC recovery technology

A system of metrics is proposed for a rough-guide evaluation of the greenness of new and existing chemical technologies as well as for the analysis of flow sheets of new processes. The proposed methodology is based on a hierarchical approach. The main feature of the proposed system is the reflection of the stakeholder relevance of various aspects of green chemistry at different levels of the hierarchy and the corresponding system boundaries. Therefore, the developed methodology provides a basis for the multiobjective comparison of alternative technologies in terms of their greenness. A novel technology for recovery of volatile organic chemicals (VOCs) using monolithic adsorbents has been evaluated in terms of its environmental efficiency using a small set of indicators assembled into a hierarchical metric. A comparison between incineration and recovery of VOCs via adsorption has been performed using the proposed methodology. The comparison highlights considerable environmental advantages of the recovery technology. Flow sheet analysis points out which stages of the adsorption process could be further improved. Indicators have been evaluated within defined system boundaries.