Effects of Minimum Cost Optimization in Water Distribution Networks on Residual Chlorine and Trihalomethanes Dynamics

Abstract

Water distribution networks (WDNs) are designed under parameters and restrictions that guarantee compliance with hydraulic and water quality conditions in the system. The optimized design of WDNs ensures a lower cost for the network, maintaining an adequate supply of the demand. The optimization process leads to the reduction of some diameters compared with those in nonoptimal networks, thus changing the hydraulic behavior and hence affecting the water quality performance. This study aims to evaluate the relationship between optimal and nonoptimal WDN designs concerning residual chlorine levels and the formation of disinfection byproducts, specifically total trihalomethanes (TTHMs). Seventeen networks were optimized using the optimal power use surface, and for each one of them four nonoptimal alternatives were generated using genetic algorithms. Residual chlorine and TTHM concentrations were analyzed in the different configurations of the networks according to their geometrical characteristics. Results indicate that optimized networks exhibit reduced chlorine consumption, consequently leading to lower TTHM formation. In particular, the optimized design achieved a reduction of up to 20.6% in chlorine consumption compared to the more expensive alternative. Future work will focus on evaluating water quality dynamics, considering event-based operational changes.