Chlorination of public water supply is the most common and widely used system for
disinfection; Brazilian law has mandatory parameters for the presence of free residual
chlorine in water supply systems, ranging from 0.2mgL-1 to 2.0mgL-1. The major
problem associated with chlorination is the presence of solubilized organic matter in
water, which reacting with free residual chlorine forms halogenated by-products known
as trihalomethanes (Bromodichloromethane, Dibromochloromethane, Bromoform,
Chloroform). In this context, the use of hydraulic models for water quality emerges as
a tool to identify distribution network locations with high detention time and
consequently higher trihalomethane formation rate. This study evaluated the chlorine
decay patterns and trihalomethane formation throughout the water distribution network
in the southern region of the city of Palmas-TO. With data associated with an adequate
geographic information system it was possible to understand the chlorine decay
patterns and all the formation and diffusion of the trihalomethanes originated in the
network. Trihalomethane concentrations were found to be significantly higher in
September; and chlorine, despite higher concentrations, tends to decline more rapidly
this month. The results have proved useful as benchmarks for future interventions in
the system aiming at an increase in operating efficiency.
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