Pressure losses across sand media filters in microirrigation systems when using reclaimed effluents

The location and evolution of the pressure losses across sand media filters commonly used in microirrigation have not been extensively studied. However, understanding these patterns may allow identifying feasible redesign strategies that reduce energy consumption and, therefore, enhance the sustainability of this irrigation equipment. The pressure loss in the main regions (diffuser, upper and lower bed media, underdrain and collector) of three media filters with different underdrain types (collector arms, inserted domes and porous media) was measured in filtration operation with two sand bed heights (0.2 and 0.3 m) and two filtration velocities (30 and 60 m/h). Each combination of filter, bed height and filtration velocity was tested for 250 h using reclaimed effluents. Higher pressure losses were observed at the greatest filtration velocity and the deepest media bed. Overall, the highest pressure loss was observed in the sand bed, with the diffuser showing the second largest loss. The evolution of pressure loss throughout each filtration cycle showed a progressive increase across the media, attributed to the accumulation of retained solids. New designs of diffusers are advisable to reduce pressure loss in both the inserted domes and porous underdrain filters, while for the arm collector filters a redesign of the underdrain should be prioritized.