Clogging formation and an anti-clogging method in subsurface irrigation system with porous ceramic emitter

Abstract

Emitter clogging negatively affects the performance of subsurface drip irrigation systems. The porous ceramic emitters of a subsurface irrigation system were investigated to identify the reasons for emitters clogging. Using 2-year operational data in an apple orchard, the soil water content and the emitters discharge were measured, the position and composition of the clogging substance were investigated, and the thickness of the adhesion layer in the channel of the emitter was calculated. Further, a flushing experiment using acid water with a pH of 6 was carried out to assess emitter clogging. The primary reason for the emitter clogging was substances precipitated at the inlet of the emitter, resulting in reducing the discharge of the emitter. At the same time, the water flow was affected by the clogging substance inside the micropore close to the channels. The main compounds of the clogging substances were SiO2, CaCO3, and MgAl2O4. Fe, Cl and K were also observed. Bacteria, fungus and microalgae secreted PLFAs to form biofilm. We have tested 4 flushing times (3 min, 10 min, 15 min, 20 min) and found that when the flushing time lasted 15 min, the corresponding emitter discharge were 0.046 L h−1 and 0.136 L h−1 under the working pressure of 2 kPa and 5 kPa, and discharge recovery rate were 51.11% and 75.56%, respectively. However, when the flushing time increased to 20 min, the discharge recovery was similar to that of 15 min. Therefore, it is recommended to flush with an acid solution for 15 min at flushing pressure of 100 kPa pressure to minimize the emitter clogging.