Efficiency of pressurized sand filters in removing different particle sizes from irrigation water

Abstract

The objective of this work was to evaluate the efficiency of sand filters of different granulometry in removing different particles sizes from irrigation water, as well as the pressure loss due to the filtration rate and sand particle size of the filter bed. The trials were conducted with three sand filters of the same commercial model, tested with different combinations of sand particle sizes (fine, 0.55 mm; medium, 0.77 mm; and coarse sand, 1.04 mm diameter) and filtration rates (20, 40, 60, and 75 m3 m^-2 h^-1), repeated in three 4‑hour filtration cycles (C1, C2, and C3, carried out in 3 consecutive days). The evaluated sand filter is effective in the removal of particles starting at the fine sand size (>60 µm). In this particle removal range, the influence of the filtration rate increases with decreasing particle size in the water. The increase in the filtration rate, associated with the reduction in sand granulometry, increases removal efficiency, but accentuates pressure loss in time, which decreases the removal of smaller particles during the filtration process.