Resources, Conservation and Recycling 55 (2011) 730–737 Contents lists available at ScienceDirect Resources, Conservation and Recycling journal homepage: www.elsevier.com/locate/resconrec Emergy-based fuzzy optimization approach for water reuse in an eco-industrial park Mohammad Sadegh Taskhiri a , Raymond R. Tan b,c,∗ , Anthony S.F. Chiu a,b a Industrial Engineering Department, De La Salle University, Manila, Philippines b Center for Engineering and Sustainable Development Research, De La Salle University, Manila, Philippines c Chemical Engineering Department, De La Salle University, Manila, Philippines article info Article history: Received 21 October 2010 Received in revised form 5 March 2011 Accepted 8 March 2011 Keywords: Emergy Eco-industrial park Interplant water reuse Fuzzy mixed integer linear programming abstract The establishment of an eco-industrial park (EIP) provides opportunity for individual plants to cooperate with each other in order to utilize resources efficiently and thus reduce waste. The goal of an EIP is to “close the loop” through recycling and reuse of material and energy streams. Studies show with current freshwater consumption trends there would be water stress aggravated by global warming in the near future. This paper presents a model to design an EIP water reuse network that considers overall system sustainability as measured with emergy, as well as cost saving desired by individual plants. Case studies from literature are then solved to illustrate the advantage of this method in decision making. The illus- trative examples show how the model achieves a compromise among the potentially conflicting fuzzy goals of the various EIP stakeholders. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Recent research shows that with current trends, global freshwa- ter consumption may soon approach the sustainable limit, and thus lead to water stress in many countries in the near future (Rockstrom et al., 2009). Lack of freshwater could have significant impact on the industrial sector, since it might affect the supply chain management of the companies. It is thus important for companies to reduce their freshwater consumption. Water reuse in industrial plant is a strat- egy which has been considered by many studies in recent decades. Although it is possible to conserve freshwater by direct water reuse, further savings can be realized by regenerating wastewater prior to reuse. However, there would be other environmental impacts due to energy consumption and greenhouse gas (GHG) emissions for building and operating water reuse networks (Ku-Pineda and Tan, 2006; Tan et al., 2007; Lim and Park, 2008; Taskhiri et al., in press). Thus, it is necessary to balance water conservation goals with other environmental aspects, in order to optimize the sustainability of an industrial system. The eco-industrial park (EIP) is a concept that could takes advan- tage of cooperation among companies to achieve environmental ∗ Corresponding author at: Center for Engineering and Sustainable Development Research, De La Salle University, Manila, Philippines. Tel.: +63 2 536 0260; fax: +63 2 536 0260. E-mail addresses: m sadegh1@yahoo.com (M.S. Taskhiri), raymond.tan@dlsu.edu.ph, natdnomyar@gmail.com (R.R. Tan), anthony.chiu@dlsu.edu.ph (A.S.F. Chiu). improvements. The concept has been implemented in many coun- tries (Ehrenfeld and Gertler, 1997; Schwarz and Steininger, 1997; Chiu and Yong, 2004; Heeres et al., 2004; Roberts, 2004; Gibbs and Deutz, 2005; Park et al., 2008; Geng and Zhao, 2009; Geng et al., 2010; Zhang et al., 2010). According to Lowe (2001), an EIP is “char- acterized by closely cooperating manufacturing and service businesses that work together to improve their environmental and economic per- formance by reducing waste and increasing resource efficiency. More specifically, EIP can be composed of firms or facilities that coordinate their activities to increase efficient use of raw materials, reduce outputs of waste, conserve energy and water resources, and reduce transporta- tion requirements.” According to Chertow (2007), wastewater exchange in an EIP is often a starting point for sharing other resources among the participating plants. For this reason, water exchange is the main focus of this work. Secondly, statistical data shows that with cur- rent trend of freshwater withdrawal coupled with climate change, there would be water stress in many countries in the near future. Recent research illustrates the advantages of water exchange in EIP’s (Geng et al., 2007; Chew et al., 2008; Lim and Park, 2008; Tian, 2008; Chew and Foo, 2009; Chew et al., 2009; Lovelady and El-Halwagi, 2009; Lovelady et al., 2009; Chew et al., 2010a,b; Aviso et al., 2010a,b, 2011; Tan et al., 2011). Note that water integra- tion in an EIP differs from conventional plant integration because it involves firms and facilities which are not owned by a single entity. There is hence the need for cooperation among the plants involved, often facilitated by a higher level authority such as the government, industrial park owner, or tenant association. In a typ- ical scenario, the plants are concerned with minimizing internal 0921-3449/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.resconrec.2011.03.001