Decay of Free Residual Chlorine in Wells Water of Northern Brazil




Ferreira Vargas, Taise
Ceolin Baía, Célia
Lemos da Silva Machado, Tatiana
Chang Dórea, Caetano
Rodrigues Bastos, Wanderley

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The concentration of chlorine in water declines as it reacts with various substances, causing decay of the residual free chlorine until its total consumption. In light of the typical characteristics of the water from protected dug wells and tube wells, this study aimed to evaluate the decay kinetics of free chlorine in the water of alternative individual supply (AIS) solutions used in the city of Porto Velho in the Brazilian Amazon region. The free chlorine decay constant in the water was evaluated by “bottle tests,” applying a first-order model. According to the results, the type of well and initial chlorine concentration significantly influences the free chlorine decay speed. The water samples from the tubular wells had lower chlorine demand levels, attributed to their better water quality. The simulation of the residual chlorine decay in the different supply sources is an important tool to support safe disinfection processes.



drinking water quality, disinfection, chlorine kinetics, Brazilian Amazon, free chlorination


Ferreira Vargas, T., Ceolin Baía, C., Lemos da Silva Machado, T., Chang Dórea, C., & Rodrigues Bastos, W. (2021). Decay of Free Residual Chlorine in Wells Water of Northern Brazil. Water, 13(7), 1-13.