Calibração do coeficiente de decaimento do cloro (kw) em redes de abastecimento de água utilizando o método iterativo do gradiente hidráulico alternativo adaptado para gradiente de concentração

Abstract

The presence of free residual chlorine (FRC) in water supply networks has two lines: one is to ensure the quality of water in case of possible contamination in the network, and the other is the formation of trihalomethanes (substances considered carcinogenic in the scientific environment) when natural organic matter is present in the network. Against this background the Ministry of Health issued Ordinance No. 2914/2011 establishing the obligation of monitoring the concentration of FRC limited to a minimum of 0.2mg/L and a maximum of 2.0mg/L at any point in the distribution network. This requirement has become a problem for water supply companies, because FRC is a non-conservative substance and its decay is influenced by several factors, the main contributors among them being the chlorine decay coefficient in the liquid (kb) and the chlorine decay coefficient in the pipe wall (k W). The purpose of this work is to calibrate the chlorine decay coefficient in the pipe wall (kW) using as a calibration tool the Iterative Method of Hydraulic Alternative Gradient (MIGHA) developed by Schuster (2004) adapted to the concentration gradient, and as hydraulic and water quality model the EPANET software.