Influence of particle size and concentration of sediment on clogging of labyrinth channels emitters

Abstract: Drip irrigation technology is widely used due to its advantages including high efficiency water saving, ability to adapt to the terrain and so on, but the problem of emitter clogging has been always a baffled to researchers. Emitter clogging basically has three classes, respectively is physical clogging, chemical clogging and biological clogging, of which the most common is physical clogging and it is represented by sediment clogging. Studies show that even if the irrigation water after precipitation filtration, there is still have particle size of sediment particles which are less than 0.1mm get into the emitters causing emitter clogging. However, previous studies on this problem multi-use of computer simulation method to research the influence of emitter anti-clogging by emitter structures, test verification is relatively rare and most studies only from a macro perspective to observe emitters clogging, no in-depth study on the clogging mechanism. In addition, the previous researches presents the sediment particle size range which are easily lead to cause emitters clogging need further verification, sediment concentration corresponding in different size which are easily to cause emitters clogging needs to be studied in-depth. So in order to investigate the influence of sediment particle size and sediment concentration on the clogging processes of labyrinth channels emitters, periodic intermittent drip irrigation experiments were carried out using muddy water containing particles with 6 different particle ranges (all less than 0.1 mm) which were screened by means of sieving method, each particle size range of sediment are formulated to 0.5,1.0,1.5 g/L of muddy water. Each irrigation time is 30min as same as the test interval, emitters flow collect real-time and replace new pipes after the end of each group of treatment. In these experiments, the changes of flow discharges were measured under a constant pressure and after the end of the trial clogging emitters are cut to dried in the natural state, then collect the sediment which depositing in the labyrinth channel, at least the locations of sediment clogging were observed using electron microscopy and take picture to compare the difference between the status quo sediment and the clogging sediment to proven mechanisms that cause clogging of sediment particle size in different range, it also provide a theoretical basis for how to select the appropriate filter. The results show that, the sensitive sediment particle range that cause easy clogging is depending on the sediment concentration. When the sediment concentration is less than 1.3 g/L, particle size is considered as the main cause of clogging. The most easily cause clogging particle ranges are between 0.075-0.1 mm and 0.03-0.038 mm; particle ranges from 0.05-0.075 mm and 0.02-0.03 mm are lesser; while the ranges that most difficult to cause clogging are 0.038-0.05 mm and less than 0.02 mm. When the sediment concentration is greater than the critical value that between 1.2-1.3 g/L, the effect of sediment particle size on clogging is weaker and sediment concentration becomes the main factor to cause clogging. The results also appeal that sediments can easily condense into aggregates to get drippers clogged when the sediment particle size range is less than 0.038 mm.