Avaliação de risco da qualidade da água de abastecimento distriuída num setor confinado de uma rede de distribuição antiga de cimento amianto

Abstract

Demands for drinking water with both large quantity and good quality have been increasingly difficulty to attend satisfactorily throughout the world. Due to its characteristics raw water has to be treated in order to attend potability standards, but quality of treated water tends to deteriorate as it is piped and distributed to consumers. This work aimed evaluating the risks associated with the water from a confined sector of the water distribution network of Campina Grande City, Paraíba state, northeast Brazil. Sentinel indicators (free residual chlorine and turbidity), combined residual chlorine, heterotrophic bacteria, pH and total coliform were analyzed in grab sample collected from nine monitoring points between March and December 2013. Failure Mode and Effects Analysis (FMEA) methodology was applied for drinking water risk evaluation which based the construction of a risk hierarchization scale. Estimation of total risk in each monitoring point was based on water quality indicator mean values and also on the hierarchical importance of evaluated risks. All points analyzed in the confined sector were classified as high risk being low free residual chlorine , high concentration of heterotrophic bacteria and the presence of total coliform the most influential hazards for such a classification.