CHEMICAL ENGINEERING TRANSACTIONS VOL. 70, 2018 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Timothy G. Walmsley, Petar S. Varbanov, Rongxin Su, Jiří J. Klemeš Copyright © 2018, AIDIC Servizi S.r.l. ISBN 978-88-95608-67-9; ISSN 2283-9216 A Multiple Input Type Optimization Model Integrating Reuse and Disposal Options for a Wastewater Treatment Facility Michael Ang, Jensen Duyag, Kimberly Tee, Charlle Sy* Department of Industrial Egineering, De La Salle University, 2401 Taft Avenue, Malate, Manila, Philippines, 1004 charlle.sy@dlsu.edu.ph In the last few years, rapid industrial development coupled with globalization have brought about significant environmental impacts from both the industrial and urban settlements. Inadequate treatment and improper disposal of wastewater is a growing problem, causing health hazards and endangering nearby marine life. As such, it is more important to implement a sustainable strategy to reduce the harmful environmental impact of untreated wastewater. Optimizing wastewater treatment operations while tapping into the reuse potential of wastewater can improve the economic viability of a treatment plant. This study presents a mathematical model formulated to optimize the treatment process of wastewater. The model takes into account different input types in terms of quantity and quality, and various output or disposal options. Also, this study introduces the use of different input treatment options – mixed, parallel, and series – to better optimize according to the stakeholder’s objectives. This integrated view of the system from input to output strengthens the model’s capability to meet stakeholder requirements and optimize operations. 1. Introduction The last decade has ushered significant global industrial development. It is estimated that an additional 2.5 billion people will be living in urban cities by the year 2050 (United Nations, 2014). The increasing world population coupled with the increasing concentration in urban cities have also led to the increase of waste generation annually, including municipal wastewater and sludge (Mateo-Sagasta et al., 2015). In some cities, wastewater and sludge are collected, treated, and beneficially reused. However, cities in developing countries are still unable to properly treat and dispose of the wastewater that growing urban cities generate. Disposal into the environment in water bodies without proper treatment causes pollution of surface and groundwater sources. Optimizing wastewater treatment operations while tapping into the reuse potential of wastewater improves the viability of the treatment process while supporting the lack of clean water supply in several regions. Typically, wastewater treatment plants have several stakeholders with varying priorities ( Belia et al., 2009). As stakeholders, the government imposes regulations for the necessary types of treatment permissible in an area and the required water quality levels allowed for disposal for each water body ( Grady et al., 2011). Another consideration for the government is the economical upliftment of the nearby community. This can be attributed through the employment opportunities that the development and operations of a wastewater treatment facility offer (Boix et al., 2015). There are various disposal and reuse options available for the wastewater treatment, which significantly affect both environmental and economic benefits of a wastewater treatment facility. However, there is a lack of integration in the current literature on wastewater regarding disposal and reuse options. As shown by Siy et al. (2016), considering both economic and environmental issues allow the model to optimize a more realistic facility setup. The environmental benefits of the optimization model can be better maximized with an integration as it matches the effluent water quality to the best suited disposal site or reuse option while taking into account the different disposal constraints set by local authorities. Disposal to water bodies that are not appropriate even after treatment can still cause environmental impact depending on the uses and composition of the water body. The treated water should be disposed to sites that would most fit its properties in order to maximize overall environmental benefit. Such integration will be demonstrated in this paper. DOI: 10.3303/CET1870034 Please cite this article as: Ang M., Duyag J., Tee K., Sy C.L., 2018, A multiple input type optimization model integrating reuse and disposal options for a wastewater treatment facility , Chemical Engineering Transactions, 70, 199-204 DOI:10.3303/CET1870034 199