A multi-objective optimization model to plan city-scale water systems with economic and environmental objectives: A case study in santiago, Chile

Abstract

Climate Change and its effects in water scarcity has become an important challenge for cities with water management problems. These problems require an integral planning of the city, which can be supported by optimization. The main goal of the research is to provide a regional optimization model for water networks, including new treatment options. The model is formulated as a multi objective mixed integer programming problem, focused on environmental and economic impact of the network, minimizing water extracted from natural sources and total cost. The formulation is developed with the goal programming methodology. The model covers a complete existing city scale water network, including 4 different options of water reuse within the city: drinking water, fresh water, irrigation, and discharge in natural courses. The case study is Santiago, capital of Chile, which is the political, economic, and insti tutional center of Chile. If both objective functions have equal importance to configure the solution, the following ideas characterize the optimal water network: (i) it is more environmentally and economically convenient to reuse water within the network rather than recycling water to the natural source; (ii) the reuse of water is preferred in the form of irrigation and drinking qualities rather than industrial qualities to reduce transport costs, and (iii) the modification of the current treatment plants is preferred, because of the high cost of installation of new plants. An environmental and cost effective solution for Santiago, Chile, can reduce the source water extraction in 35.7%. The model can be implemented in other contexts, providing orientations to decision makers so as to plan city scale water networks with simultaneous environmental and economic considerations.

Modeling Frictional Head Loss in the Redesign of City-Scale Water Networks through Multiobjective Optimization: Strategies to Deal with Nonlinear Terms

“…This paper is based on a previous one where the simplified smallscale problem is presented. 5 In that research, a multiobjective optimization model was developed, applying the elimination of nonlinearities as a simplification strategy. The point is whether this strategy is the best among the available.…”

“…The model applied to this problem is based on the previous paper by Gormaz-Cuevas et al 5 The proposed model is based on the superstructure shown in Figure 2. As described in Gormaz- Cuevas et al, 5 the model consists of a set of mass balances in the treatment plant nodes, distribution and collection nodes, and consumption nodes.…”

“…2−,4 A proper optimization model can help to reduce costs and environmental impacts, using alternative sources or improving treatments. 5 The optimization of water networks has been covered in the literature. 6 These problems are numerically hard to solve because of their nonlinear equations.…”

“…Then, the problem structure is presented, based on a previous paper. 5 The following section presents the case study, and the next sections present the results of this research, their discussion, and conclusions.…”

Sensitivity analysis of parameters affecting suspended growth in industrial wastewater treatment plants; with emphasis on economic performance criteria

“…No one doubts the necessity of wastewater treatment due to its high amount of physical, chemical, and biological pollution which is only reachable through treatment plants. However, the high costs of these large-scale projects have led experts Citation: Gheibi to fi nd the most appropriate process that, besides meeting quality parameters, optimally satisfi es the technical, economic, and environmental goals [12][13][14][15][16]. On the other hand, each of these treatment plants and related processes has special characteristics and attitudes.…”