Estudo de dimensionamento de filtro lento retrolavável de camada simples (areia) e dupla camada filtrante (areia e antracito).

Abstract

Backwashed slow sand filtration (FLR) is an excellent alternative for treating supply water in rural areas, on a household scale or for small communities. The present study aims to dimension the already consolidated FLR with a single layer (sand) and the innovative FLR with a double filter layer (sand + anthracite), with the aim of comparing important parameters such as head loss in the clean filter medium, minimum speed of fluidization of the filtering medium, percentage of expansion of the filtering layer during backwashing, volume of water for washing and the height of the water reservoir for backwashing. Using the specific literature, the sizing was based on a filtration rate of 4 m³/m². d, in a 100 mm filter, producing around 31 liters of treated water per day. The results showed that the head loss between the clean filter media was 0.05 m for the single-layer FLR, and 0.08 m for the double-layer FLR. The minimum fluidization velocity of the single-layer FLR was 3.4x10-3 m/s, and the double-layer FLR was 2.5x10-3 m/s, leading to an excessive expansion of the anthracite, when compared to recommendations of literature. Thus, the FLR-single layer filter media expanded 42% and the FLR-double layer 32% for sand and 143% for anthracite. The volume of water for backwashing the single-layer FLR was 9.7 liters, higher than the double-layer FLR, which was 7.1 liters. Finally, the height of the water reservoir for backwashing in relation to the double-layer FLR gutter was 0.40 m, lower than the single-layer FLR, which was 0.56 m. It was concluded that the FLR-double layer is more economical from the point of view of the volume of water for backwashing, in addition to producing water faster, after cleaning the filter medium, due to the lower height of the reservoir in relation to the collection chute. wash water. At the end of the sizing, recommendations and technical notes were made available.