New composite sustainability indices for Cradle-to-Cradle process design: Case study on thinner recovery from waste paint in auto industries

In a conventional chemical process design, the main focus is on the process economy resulting in the generation of huge amounts of waste materials within the process. Such design approach demands end-of-pipe treatment, which is neither profitable due to the hefty costs of the installation and operation of large scale waste treatment facilities, nor environmentally conscious due to the potential impacts of the generated wastes within the process on the environment. The recent approach to sustainable process design has surmounted this challenge. This paper presents a new application of an already introduced composite sustainability index (CSI) that requires minimum amount of data to monitor the sustainability performance of a chemical process and troubleshoot, if necessary. Then, the CSI is applied to an existing process for the purpose of Cradle-to-Cradle design by significant reduction of the environmental impacts of the process, and the escalation of the plant profitability due to sustainable retrofitting of the plant. The CSI methodology can be applied to chemical, refinery, petrochemical, oil & energy, fuel and biofuel processes. The three main advocates have been considered in the CSI, which are the impacts of “energy” and “material” on the environment as well as “risk assessment”. The CSI is technically imperative at all engineering stages of above process plants with the aim of source reduction and environmental protection. The CSI gives process and safety engineers a competitive edge, making their designed process stand out amongst other design array. The current study proves that the CSI methodology is a powerful tool for process and safety designers, and that the process sustainability and profitability are strongly linked. So, it is specifically decisive at managerial level pursuant to strategic planning towards company's sustainability.