Article

A holistic framework for design of cost-effective minimum water utilization network

Chemical Engineering Department, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia.
Journal of Environmental Management (Impact Factor: 2.72). 08/2008; 88(2):219-52. DOI: 10.1016/j.jenvman.2007.02.011
Source: PubMed

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 minimization problem. Strictly speaking, WPA can only lead to maximum water recovery targets as opposed to the minimum water targets as widely claimed by researchers over the years. The minimum water targets can be achieved when all water minimization options including elimination, reduction, reuse/recycling, outsourcing and regeneration have been holistically applied. Even though WPA has been well established for synthesis of MWR network, research towards holistic water minimization has lagged behind. This paper describes a new holistic framework for designing a cost-effective minimum water network (CEMWN) for industry and urban systems. The framework consists of five key steps, i.e. (1) Specify the limiting water data, (2) Determine MWR targets, (3) Screen process changes using water management hierarchy (WMH), (4) Apply Systematic Hierarchical Approach for Resilient Process Screening (SHARPS) strategy, and (5) Design water network. Three key contributions have emerged from this work. First is a hierarchical approach for systematic screening of process changes guided by the WMH. Second is a set of four new heuristics for implementing process changes that considers the interactions among process changes options as well as among equipment and the implications of applying each process change on utility targets. Third is the SHARPS cost-screening technique to customize process changes and ultimately generate a minimum water utilization network that is cost-effective and affordable. The CEMWN holistic framework has been successfully implemented on semiconductor and mosque case studies and yielded results within the designer payback period criterion.

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    • "One approach for water resource management in waterintensive industries is water network design, which includes design in both production and secondary use levels. Design of water network , by means of graphical methodologies (Alwi et al., 2008; Manan et al., 2006), mathematical programming (Feng et al., 2007) and synthesis of mass exchange networks (Shafiei et al., 2004), has been applied to allocate streams between operational units within the water system, due to the increased interests for sustainable development in industries (Boix et al., 2012). The purpose of water network design is to maximize water generation and reuse water into the industrial processes (El-Halwagi et al., 2003). "
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    Full-text · Article · Jan 2015 · Resources Conservation and Recycling
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    • "Although this may seem like an impossible task, if it is seen as a best practice end goal, it can drive innovation and achievement in water use minimisation (Lens et al., 2002). Wan Alwi et al. (2008) suggest that ZLD is most likely to be achieved by following the water minimisation hierarchy (WMH), where water use should focus on, in decreasing priority; 1. Source elimination: Remove water requirements; 2. Source reduction: Reduce water requirements; 3. Reuse water: Reuse water directly without treatment; 4. Regenerate water: Reuse water following treatment (also known as recycling); 5. Use fresh water: When the use of 'new' water cannot be avoided. "
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    ABSTRACT: Water is economically cheap, which fails to consider its intrinsic environmental and social value. However, given the uncertain future around the availability of water resources to provide industrial, environmental and social services, water conservation is now of significant concern to industries across the globe. Recently, an extension of water conservation has emerged as zero liquid discharge, whereby no water at all is released from industrial processes, regardless of its quality. Water auditing is a tool that can be used to identify water conservation strategies, ideally leading to zero liquid discharge. This article discusses a water audit conducted on a sodium cyanide plant, where flows were determined using historical data, proxy data, and known scientific relationships. Water quality throughout the process was defined as contaminated or uncontaminated. From this simple audit, two major water conservation measures were identified and modelled which could reduce inputs and outputs by ~40 %. These were the reuse of rainwater falling throughout the plant’s boundaries instead of demineralised scheme water, and the improvement of the efficiency of one of the cooling towers. Such a methodology could be easily applied by other industries so as to improve their water conservation. The auditing method may lead to suggestions of conservation techniques for implementation either through retrofitting existing plants or contributing to the design of new ones.
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    • "On the other hand, the minimum water targets can only be achieved when all possible methods are employed to holistically reduce fresh water consumption through elimination, reduction, outsourcing and regeneration. A systematic water reductions technique through water management hierarchy (WMH) was introduced by Wan Alwi and Manan [1] to give new insight in process modification and its application was further demonstrated in Wan Alwi et al. [2]. The process changes are systematically implemented in terms of priority through a clear guidance. "
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    ABSTRACT: This work presents the development of a new systematic technique to target fresh water consumption and wastewater generation for systems involving multiple contaminants when all options of water minimization including source elimination, reduction, reuse/recycle, outsourcing and regeneration are considered simultaneously. This problem is formulated as mixed integer linear programming (MILP) and implemented in Generalized Algebraic Modeling System (GAMS). The consideration of process changes will lead to optimal design of minimum water utilization network. The MILP model proposed in this work can be used to simultaneously generate the minimum water targets and design the minimum water network for global water-using operations for buildings and industry. The approach is illustrated by using an industrial involving a chlor-alkali plant. Significant water savings for the industrial case study is achieved, illustrating the effectiveness of the proposed approach.
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