A cloração é o método mais utilizado para promover a desinfecção da água para consumo humano. Durante a passagem de água clorada em sistemas de abastecimento de água, a concentração de cloro residual livre (CRL) decai, cuja taxa de reação depende das características da água natural. Neste trabalho, foi avaliado a decadência da concentração de residual de cloro livre em dois tipos de água, subterrânea e superficial, com diferentes concentrações de matéria orgânica, sob a perspectiva da influência do tempo de deslocamento da água, dependente dos cenários de consumo nas redes de distribuição, cujos módulos de abastecimento são caracterizados por baixa adensamento populacional e operam sob as condições iniciais de demanda previstas nos projetos. Foi considerado o efeito da temperatura e do carbono orgânico total (COT) sobre os valores das constantes cinéticas de decaimento de massa (kb), utilizadas nos modelos matemáticos que simulam a qualidade da água. Os tempos de viagem nos nós mais críticos e as concentrações mínimas de desinfetante na entrada do módulo de abastecimento para cumprir a legislação foram iguais a 40 horas e 0,27-0,28 mg L-1 para as redes de distribuição do condomínio Vale dos Pássaros e 144 horas e 0,30-0,36 mg L-1 para o condomínio Terras Alphaville.
Palavras-chave: COT; desinfecção; qualidade da água
Chlorination is the most widely used method for disinfecting water for human consumption. While the chlorinated water travels through a distribution system, the concentration of free residual chlorine (FRC) declines depending on the natural water characteristics. This study investigated FRC decay in two types of water sources - ground and surface water - with varied concentrations of organic compounds. The travel time variable depended on water consumption patterns of both distribution systems which attend low density populations and their initial project needs. Based on mathematical simulation techniques of water quality models, the study also investigated the effects of water temperature and total organic carbon (TOC) on the kinetic constants (kb) of chlorine decay. Results show that travel time in the most critical locations in the water networks and the minimum disinfectant concentrations required at the entry points were 40 hours and 0.27-0.28 mg L-1 at Vale dos Pássaros housing complex, and 144 hours and 0.30-0.36 mg L-1 at Terras Alphaville housing complex.
Keywords: disinfection, TOC, water quality
Chlorination is the most widely used method for disinfecting water for human consumption. While the chlorinated water travels through a distribution system, the concentration of free residual chlorine (FRC) declines depending on the natural water characteristics. This study investigated FRC decay in two types of water sources - ground and surface water - with varied concentrations of organic compounds. The travel time variable depended on water consumption patterns of both distribution systems which attend low density populations and their initial project needs. Based on mathematical simulation techniques of water quality models, the study also investigated the effects of water temperature and total organic carbon (TOC) on the kinetic constants (kb) of chlorine decay. Results show that travel time in the most critical locations in the water networks and the minimum disinfectant concentrations required at the entry points were 40 hours and 0.27-0.28 mg L-1 at Vale dos Pássaros housing complex, and 144 hours and 0.30-0.36 mg L-1 at Terras Alphaville housing complex.
Keywords: disinfection, TOC, water quality
