Municipal Wastewater Reuse: Is it a Competitive Alternative to Seawater Desalination?

Dafne Crutchik,José Luis Campos

doi:10.3390/su13126815

Abstract

Water scarcity is becoming a global challenge to attempts to narrow the water demand–supply gap. To overcome this problem, it is sensible to consider alternative technologies that can exploit non-conventional water resources. The choice of such technologies should be, however, carefully analyzed, because any choice might be unfeasible from an economic point of view. In this work, a methodology to select the most appropriate non-conventional water resource, out of municipal wastewater and seawater, was proposed. Specifically, we attempted to determine which alternative provides cheaper water supply and production costs for domestic uses, depending on the wastewater treatment system used and the water plant capacity. The production of water under three scenarios was analyzed: (i) a city that has a conventional wastewater treatment plant (WWTP); (ii) a city that uses primary treatment and submarine outfalls to treat municipal wastewater; (iii) seawater desalination. The proposed methodology was tested in Chilean cities that are located in areas where water is a scarce resource. The results showed that the reuse of municipal wastewater represents a cost-competitive alternative to seawater desalination, mainly when municipal wastewater is treated in a conventional WWTP and when water flow demand is higher than 1500 m3/d. In contrast, seawater desalination becomes more profitable than wastewater reuse when the treatment of municipal wastewater is based on the use of submarine outfalls. This study provides a useful economic tool for promoting municipal wastewater reuse as a non-conventional water source for supplying water to cities that suffer from water scarcity in Chile and in similar areas of the world.

Highlights

Water scarcity has been recognized as a serious global issue of this century
Even when seawater desalination has considerable water supply potential, for countries like Chile due to its abundance and availability, the reuse of municipal wastewater represents an economical alternative to seawater desalination for the production of water
When the treatment of municipal wastewater is based on the use of submarine outfalls, seawater desalination becomes more profitable than wastewater reuse for the production of water flow rates lower than 70,000 m3 /d

Summary

Introduction

Water scarcity has been recognized as a serious global issue of this century. At present, around 25% of the world’s population live in areas that experience water stress, and it is estimated that more than half of the global population will experience severe water scarcity in the coming years [1]. In the context of water scarcity, it is imperative to use water more efficiently This is not enough, and it is necessary to explore alternative and sustainable technologies to exploit non-conventional water resources (e.g., seawater, wastewater, rainwater, fog, among others) [3,4,5]. Among these alternative water supply technologies, membrane-based separation processes, reverse osmosis, provide an opportunity to deal with water scarcity in many water-stressed regions around the world [6,7,8,9].

Methods

Results

Conclusion