Seepage irrigation has been one of the most concerned irrigation technologies in recent years, due to its energy saving, high yield, and water use efficiency. However, the performance of ceramic emitter varies greatly under different water quality conditions. Particularly, there are various working modes in the ceramic emitter and conventional maze channel emitter. This study aims to explore the anti-clogging performance and clogging mechanism between the ceramic emitters and labyrinth channel emitters under different water quality irrigation conditions. The test platforms were also composed of the water storage bucket, electric pump whirlpool type self-priming electric pump, pressure gauge, mesh filter (125 microns), control valve, emitter, capillary, and return tank. The experiment was selected as brackish water (A1), fertilizer water (A2), and brackish water with fertilizer (A3). The ceramic emitters and six types of labyrinth channel emitters were selected for the continuous irrigation experiments. The discharge ratio variation (Dra) was then monitored under different irrigation conditions of water quality. An X-ray diffractometer (XRD) test was conducted to identify the clogging substance. A Scanning Electron Microscopy (SEM) was then utilized to characterize the surface morphology and growth process of the clogging substances. The results showed that: 1) The excellent anti-clogging performance was achieved in the ceramic emitter under saline irrigation. The anti-clog time of the ceramic emitter was prolonged compared with the maze channel emitter. The chemical blockage was the main cause of the blockage, which was produced CaCO3 by chemical reactions of ions in brine. The chemical blockage was gradually reunited from the loose crystals to combine into the larger particles in the process of irrigation. Although the microhole was not completely covered in the inner wall of the ceramic emitter, the cross-section of labyrinth channels of the emitter was quickly reduced to plug the inner wall of the ceramic emitter rather than the pores. The tiny runner of the labyrinth channel emitters was then deposited to rapidly reduce the flow in the labyrinth channel emitter. 2) The ceramic emitter dropped rapidly at the high temperature and humidity under the fertilizer water irrigation, indicating the low clogging resistance on the whole. The blockage was mainly (NH4)2SO4 under the fertilizer water irrigation. That was because the proteins secreted by microorganisms were separated out in a highly saturated ammonium sulfate solution, and (NH4)2SO4 was wrapped in the protein and deposited on the inner wall of the emitter or in the flow channel. The blockage type was mainly a physical blockage, together with a biological blockage. Once the ceramic emitter flowed out from the inner wall, the precipitated protein flocculent cannot be discharged to deposit in the inner wall. As such, a dense layer of the membrane was formed on the inner wall. The very small microhole was fully clogged on the inner wall, resulting in the serious blockage of the ceramic emitter. The protein was suspended in the labyrinth channel emitters, then discharged with the water flow. Only a thin layer of membrane was attached to the runner wall, which was less impact on the area of the cross-section area. In addition, the ptfe tape was found to clog the water inlet in the labyrinth channel emitters, leading to a rapid early decline in the emitter flow. 3) The flow rate of ceramic emitter also decreased rapidly, when the temperature and humidity were higher under the saline water with the fertilizer irrigation. There was the most serious blockage at the end of the test, indicating a lower anti-blockage performance. The blockage was mainly (NH4)2SO4 Similar to fertilizer water irrigation, the physical blockage was dominated to accompany by biological blockage. The blockage process was also similar to fertilizer water irrigation. The dense membrane was formed on the inner wall of the ceramic emitter, where the flow rate decreased rapidly. At the same time, there was a thin blockage attached to the runner wall of the labyrinth channel emitters, where the flow rate decreased slowly. A large amount of EDTA chelator in the fertilizer was combined with the calcium and magnesium ions to form a chelation state soluble in water, which can effectively reduce the generation of chemical precipitation. The research results can also provide a theoretical basis to promote the anti-clogging performance of ceramic emitters. © 2022 Chinese Society of Agricultural Engineering. All rights reserved.
