Minimum water network design for fixed schedule and cyclic operation batch processes with minimum storage capacity and inter-connections

Mathematical programming techniques have been widely used to solve water minimisation problems. Yet, to date, there is lack of research on water minimisation for fixed schedule and cyclic operation batch processes that also targets the minimum storage capacity as well as inter-connections, and considers mass-transfer based (MTB) and non-mass transfer-based (NMTB) operations, for problems with multiple contaminants. In this study, a four-stage mathematical model is formulated to address the aforementioned problem, by considering water minimisation options within a Water Management Hierarchy (WMH). The developed model was employed on an urban and an industrial facility to demonstrate the effectiveness of proposed model to solve the minimum water network with minimum storage tank capacity and network inter-connections. For the urban facility case study involving a mosque, the maximum potential freshwater and wastewater reductions are 99.89% and 65.7%. Setting the minimum number of inter-connections (MNI) as the objective function has further reduced the MNI by 13%. For the industrial case study, the maximum potential freshwater and wastewater reductions are 59.53% and 16.43%. Imposing the MNI constraint as the objective function further reduced the number of inter-connections by 20.83%.