GreenPro: a new methodology for cleaner and greener process design

Chemical and allied industries have shown interest in reducing pollution by implementing cleaner technologies or processes that use, or generate, lower amounts of or less harmful pollutants. However, abatement processes are still required at many plants to reduce the discharge of pollutants at the end-of-the-pipe. It has been observed many times that efforts made to optimise the abatement process reduce the quality and/or quantity of waste discharge at the end-of-the-pipe, but increase the total environmental burden and impact. Therefore. it is very important to consider the environmental burden and adverse impacts caused due to any change or modification in the process and allied facilities for the complete system (up- and downstream of the process). Moreover, these measures have generally been taken only after fully fledged design of the process or at the operating stage, thus making the preventive/abatement measure a costly affair. Therefore, there is great need for a design process (applicable to the early design and decision-making stages) that not only considers economy and technology as the basic input for the design, but also considers environmental soundness as one of the important parameters. This paper proposes a systematic methodology for process design that considers the assessment and minimisation of the environmental impacts of the complete process system (including upstream processes), It incorporates life cycle analysis (LCA) principles within a formal design process and optimisation framework. This proposed process design methodology with minimum environmental impact extends to a complete description of the environmental impact of the process and its associated activities. It has good real-life application potential, as it includes environmental objectives together with technology and economics at the design stage so as to determine a cost-efficient solution. Further, by employing process modelling and optimisation techniques. it yields optimal design/operating conditions with minimum environmental impact. The applicability of the proposed methodology has been demonstrated through a real case study. The most interesting observation made in the case study is that the total cost of the optimised operation is minimum when the process is designed and optimised considering the global boundary (the "cradle to the grave" approach) in contrast to the conventional boundary (process boundary). (C) 2001 Elsevier Science Ltd. All rights reserved.