Effects of lateral flushing on emitter clogging and biofilm components in drip irrigation systems with reclaimed water

Emitter clogging has become one of the main restrictions in the development of drip irrigation with reclaimed water. Numerous studies have found that emitter clogging is closely related to the formation and growth of biofilms attached within the emitter wall, raising the question of how to effectively control the formation of biofilms, which is the key to solving emitter clogging. Lateral flushing could promote the rapid shedding of biofilms and wash the irrigation system by increasing the hydraulic shear force within the laterals; this would reduce the frequent shedding of biofilms from the lateral walls into the emitter during the irrigation operation and the clogging of the emitter. Therefore, we conducted an in situ drip irrigation experiment with reclaimed water in a sewage treatment plant under three conditions of lateral flushing frequency (triweekly, biweekly, and weekly), and the dynamic changes in emitter clogging and biofilm components were studied. We found that lateral flushing can effectively slow down emitter clogging in a reclaimed water drip irrigation system. The values for the discharge ratio variation and coefficient of uniformity were the highest, and those for solid particles and phospholipid fatty acids were the lowest for the biweekly lateral flushing frequency. However, lateral flushing failed to completely solve the emitter clogging problem, and some additional measures must be combined with this process to control emitter clogging problems.