A new holistic framework for design of cost effective minimum water network

Abstract

Water pinch analysis (WPA) is a well-established tool for the design of a maximum water recovery (MWR) network. MWR, which is primarily concerned with water recovery and regeneration only partly addresses water minimisation problem. Strictly speaking, WPA only leads to MWR targets and not the minimum water targets as widely claimed by researchers over the years. The minimum water targets could be achieved when all options for water minimisation including elimination, reduction, reuse/recycling, outsourcing and regeneration have been holistically applied. To date, research towards water conservation from the holistic water minimisation viewpoint has lagged behind. This thesis presents the development of a new holistic framework for designing a minimum water network for industry and urban systems. The framework consists of five key steps, i.e. (1) Specify the limiting data, (2) Determine the MWR targets, (3) Screen process changes using water management hierarchy (WMH), (4) Apply Systematic Hierarchical Approach for Resilient Process Screening (SHARPS) strategy, and (5) Network design. Six key contributions have emerged from this work. First is the development of a minimum water targeting and design procedures for urban system. Second is the development of a new holistic framework to systematically guide, prioritise and quantitatively evaluate water minimisation options for grassroots and retrofit designs for urban and industrial systems. Third is the introduction of a unique and comprehensive water management hierarchy for screening process changes. Fourth is the new SHARPS technique which provides a quick and efficient means to screen inferior process changes and to predict the fresh water savings and desirable investment limits prior to design/retrofit. Fifth is the multiple utility targeting method using source-sink composite curves and the sixth contribution is the new network design technique using source-sink composite curves. The methods were successfully implemented on semiconductor and mosque case studies and yielded significant savings within designers’ payback period criterion.