Avaliação da remoção de turbidez em filtros do tipo rápido de fluxo descendente sob diferentes concentrações de pré-cloração

Abstract

The quality of public water supply directly affects the health of the population. For this reason, the Ministry of Health through Ordinance 2914/11 requires the control of turbidity through the maximum limits established for water after filtration, which for the fast filters is 0.5 uT and 1.0 uT for the slow filters, aiming the removal of pathogenic microorganisms present in raw water. The study of the quality of raw water and filtered water is fundamental in the identification of flaws and consequent proposition of improvements to meet the current Ordinance. The present study developed in the Water Treatment Station - ETA Alto Sertão consisted in the evaluation of the efficiency of turbidity removal in ten descending rapids filters, as a function of different pre-chlorination concentrations. This evaluation by means of the analyzes carried out by collecting the turbidity of the water in the entrances and exits of the filters at different times allowed to observe the behavior of these units under the operational conditions. The turbidity removal efficiency of the filters with a relatively low pre-chlorination ranging from 20 kg / d for 25 kg / d in which only two units showed a 51% removal, while the eight units reached removals of less than 32%, when using a concentration greater than 40kg / d there was 50kg / d in chlorination, it was observed higher percentages of turbidity removal in the filtration process, with a difference of up to 30%. Although the turbidity reduction is representative, it is concluded that the filtered water does not meet, on average, the Potability standard for this parameter.