Avaliação de um filtro lento com meio filtrante alternativo no tratamento de água de rio.

Abstract

Slow filtration is a water treatment system indicated, mainly, for serving rural and isolated communities, where access to drinking water is more difficult. With the use of slow filtration, it is possible to efficiently remove impurities contained in the water, including suspended and dissolved particles and pathogenic microorganisms, by passing through the filter medium. That said, this work aimed to evaluate the treatment of river water in a slow filter with an alternative filtering medium of kaolin residue, as well as the use of backwashing to benefit the cleaning of the filters. For this purpose, a pilot-scale slow filter was used, with a triple layer of kaolin residue in different particle sizes, descending flow and intermittent operation. The filter was fed daily with river water, except on weekends and holidays, and the filtration rate of 6 m³/m².day was maintained by controlling the flow in a rotameter installed at the filter inlet. To evaluate the efficiency of the treatment, the parameters turbidity, apparent color, pH, electrical conductivity, total coliforms and Escherichia coli (E. coli) were analyzed. The results showed that the filter removed 58.04 ± 1.91% of turbidity, 49.84 ± 4.69% of apparent color, the pH remained between ranges 6 to 9, electrical conductivity averaged 273.11 ± 3 .49 μS/cm, also removed 1.24 ± 0.01 log of total coliforms and 1.19 ± 0.01 log of E. coli. Therefore, the results were important to encourage and point out a possible use of kaolin residue, contributing to the sustainability of this activity, in addition to collaborating with the understanding of water treatment in slow filters with an alternative filtering medium, covering possibilities of water potability in regions of difficult access and in situations of sand scarcity.