Effects of microorganisms on clogging process and clogging substances accumulation of drip irrigation emitters using the high-sediment water sources

The microorganisms in the water sources are closely related to drip irrigation emitter clogging and clogging substances accumulation. However, few studies quantitatively considered the role of microorganisms in the emitter clogging process, especially in the high-sediment water source. The coupling process and mechanism between solid particles and microorganisms are not clear yet. Based on these, the Yellow River water (CK), general high sediment water (GHS) and artificial simulated Yellow River water (SYR) was applied in an indoor controllable experiment to study the long-term dynamic drip irrigation emitter clogging process, microorganism growth and its secretions as well as clogging substances accumulation. The results showed that the presence of microorganisms could accelerate the clogging process, with smaller discharge ratio variation (Dra) and Christiansen coefficient of uniformity (CU), and higher accumulation of clogging substances. Among them, the Dra and CU of the SYR treatment were the smallest at the end of the experiment (14.7% and 30.5%, respectively) and those of the GHS treatment were the largest (21.2% and 33.9%, respectively). Meanwhile, the total amounts of phospholipid fatty acids (PLFAs), extracellular polymer substances (EPS) and dry weight (DW) in SYR treatment were the highest, which were 110.2%, 23.8% and 16.7% higher than those in GHS treatment, respectively. The clogging parameters and clogging substances accumulated from the CK treatment were in a state of in-betweenness. However, the differences between CK and SYR treatments did not reach a significant level, while they were both significantly different from GHS treatment (p < 0.05). This mainly resulted from the interactions between solid particles and microorganisms in the drip irrigation emitter clogging process. Ignoring the existence of microorganisms may overestimate the Dra and CU by 6.5% and 3.4%, respectively. This offered theoretical references to the application of high-sediment water in the drip irrigation system.