Dynamic effects of chemical precipitates on drip irrigation system clogging using water with high sediment and salt loads

Introducing low quality water to micro irrigation system comes up with higher risk of emitter clogging and affects its practical applications in fields. Assessment of major components growth process of clogging substances and its influence on clogging to reveal the clogging mechanism become unavoidable. A drip irrigation experiment with four irrigation and flushing treatments was conducted to study the chemical precipitates dynamic variations of chemical precipitates in clogging substances. 8 types of flat emitters subjected, and clogging samples were collected when emitter clogging degrees reached 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, respectively. X-ray diffractometer was applied to identify the mineral components. The results showed that both chemical and physical clogging occurred in all 4 operation modes and the primary chemical precipitates such as quartz and silicate (muscovite, alkali feldspar, chlorite and carbonate, dolomite, calcite) were found in emitter clogging substances. At the end of the experiment, their quantity accounted for more than 98%. Flushing treatment would slow down the accumulation of clogging substances in emitters. Although mixing these two water sources in same volume was equal to reduce the sediment and salinity concentrations to a half, the clogging degrees did not reduce as much as expected. On the other hand, positive linear correlations were observed between all three kinds of chemical precipitates and the clogging degrees, in which relative radius (A(1/2)/L) and mean velocity of flow path cross-section (v) showed significant impact, and thus affected the dynamic growth of chemical precipitates in clogging substances.