Optimum reliable operation of water distribution networks by minimising energy cost and chlorine dosage

Abstract

In recent decades much attention has been paid to optimal operation of water distribution networks (WDNs). In this regard, the system operation costs, including energy and disinfection chemicals, as well as system reliability should be simultaneously considered in system performance optimisation, to provide the minimum required level of performance in failure condition and to manage economic limitations. In this study, multi-objective optimisation of water distribution network performance in 3 different scenarios was considered. In these scenarios the effects of time-dependent chlorine injection and pump speed, as well as different combinations of objective functions for minimising energy and disinfection costs and for maximising hydraulic reliability and quality-based reliability are incorporated. As the optimisation method, a multi-objective ant colony optimisation (ACO) algorithm was used because of its high efficiency. For better managing the hydraulic behaviour and water quality in the WDN, considering temporal variations of demand, it is suggested to use variable speed pumps (VSP) as well as to inject chlorine at a variable rate. Application of VSP and time-dependent chlorine injection results in improvements such as reduction in energy and disinfection costs, and decrease in disinfection costs in application of HDSM (head-driven simulation method). In HDSM simulation of WDN, a decrease in hydraulic reliability because of shortages in water supply can be mitigated through extra chlorine injection and increase in qualitybased reliability. To deal with this challenge, it is recommended to satisfy the hydraulic reliability first and then to evaluate the quality reliability. Furthermore it is necessary to modify the hydraulic reliability relationship to incorporate different components of the WDN other than pumps. This will provide more reliable results for evaluation of the system performance.

Investigation of Optimum Sustainable Designs for Water Distribution Systems from Multiple Economic, Operational, and Health Perspectives

“…In Ref. [16], the authors optimized the design of WDSs in a multiobjective manner, incorporating both the hydraulic design (by optimizing the pump speed) and water quality design (by optimizing the chlorine dosage). They proposed three scenarios to minimize energy and chlorine costs while maximizing the network's hydraulic reliability.…”

Energy–water and GHG nexus: A South African water industry case

“…The objective of this study is to review the SA energy-water-GHG nexus and compare it to international best practice. The use of international best practises assisted in the construction of a off-peak hours the same pump will apply excess pressure to the network, resulting in a higher energy consumption than required (Babaei 2015). VSDs are able to align the pump output flow/pressure directly to the process requirements, which improves the process performance.…”

“…VSDs are able to align the pump output flow/pressure directly to the process requirements, which improves the process performance. Thus, the use of VSDs on motor pumps, which rotate at a lower speed at off-peak hours, are recommended as one method for water networks to save energy (Babaei 2015).…”

<b>Artificial neural networks to control chlorine dosing in a water treatment plant

“…Predicted rate was calculated from physical and chemical parameters of previous periods forwarded during the training of artificial neural networks (Rodriguez & Sérodes, 1996;Rodriguez, West, Powell & Sérodes, 1997). Alternative studies on measurement and management of free residual chlorine have been performed, such as decentralized monitoring in a distribution system to investigate the possibility of reducing residual rates (Soyupak et al, 2011;Chang, Gao, Wu, & Yuan, 2011;Islam, Sadiq, & Rodriguez, 2013;Ammar, Abid, El-Bindary & El-Sonbati, 2014;Babaei, Tabesh, & Nazif, 2015).…”