In the previous two chapters we have highlighted two sets of important environmental approaches namely; greener chemistry and cleaner technologies (chapter 10) and greener choices in process industry (chapter 11). Clearly, cleaner production by means of waste minimization, recycling of water and solvents, application of greener chemistry and cleaner technologies (in the context of chemical process industry) and making environmentally defendable choices belong to the set of preventive programmes that could potentially be undertaken by the process industry as in-house projects.

However, many of the interventions highlighted in chapters 10 and 11 might be more relevant during setting up of new process plants or up gradation or modernization of existing process plant by discarding the existing technology and equipment. In these contexts, the practitioners of PEM encounter diverse challenges. First, a typical small-scale (and even at times medium scale) manufacturer would like to discard the prevailing technology or equipment only after the initial investment has paid back dividends. Thus, any suggestions for discarding or scrapping of potentially useful equipment or technology may not be implemented readily by the entrepreneurs, even though the technology substitution or modernization could make sense from an environment point of view.

In this chapter, we focus on tapping the potential retrofitting of unit operations and processes within a given process industry to facilitate a service or manufacturing a product at a lower environmental cost. To achieve this, process integration and redesigning could be among the best of approaches.