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As drip irrigation develops rapidly worldwide, the need for a standardized method to evaluate emitters' clogging sensitivity is reinforced. Methodologies for evaluating the sensitivity of emitters to clogging enable identification of trends in the change in performance of emitters operated under clogging risk, selection of emitter designs with higher performance for a given set of water characteristics, and recommendation of a consistent filtration method and maintenance routines. In this study, a clogging test protocol for evaluating the sensitivity of emitters to clogging caused by suspended solid particles was assessed to improve the reliability of test results and analyze the impact of sample size (number of emitters) on clogging result accuracy. Two models of integrated non-pressure-compensating emitters were tested in three replications. The 160-h clogging test procedure consisted of four 40-h stages that varied in size and concentration of solid suspended particles. The results enabled accurate assessment of the combination of size and concentration of particles that caused clogging in each emitter model, thereby revealing trends in the sensitivity of emitters to clogging, which were not dependent on emitter sample size. Recommendations for an international standardized clogging test protocol are proposed. [ABSTRACT FROM AUTHOR]

To better understand the physical and biological clogging in drip-irrigation, a study was conducted on the impacts of hydrodynamic conditions on clay particle deposition and biofilm development in drippers using an optical method. A transparent milli-fluidic system composed of labyrinth channels was used to identify areas most susceptible to particle clogging using two different types of clay suspensions: sodium bentonite and kaolin. The impact of salt addition [(NaCl) = 200 mg L− 1] on the clay deposition was also analyzed. Biofilm development was studied using the same methodology using a nutritive solution (chemical oxygen demand, COD = 200 mg L−1). In addition, fluid dynamics simulations were performed along the labyrinth channel to understand the effect of flow behaviour on the fouling. Computational fluid dynamics results show two types of flow topology: high velocity in the main flow (around 1 m s− 1) and low velocity in the vortex zones (less than 0.2 m s− 1) found in the channel corners. Using an optical method, kaolin deposition and biofilm growth in the dripper were observed to occur mainly in the inlet channel and initial vortex zones, which are characterized by lower mean velocity and turbulent kinetic energy values. This part of the dripper can be considered as a bottleneck that amplifies the fouling phenomena and which should be optimized. With the addition of NaCl, kaolin particles tend to form bigger flocs. Therefore, more significant particle deposition is observed, but this is not the case of bentonite for which no fouling is observed along the dripper. [ABSTRACT FROM AUTHOR]

Emitter clogging is a major problem in microirrigation systems, which may result from the isolated or combined effects of physical, chemical, and biological agents. Clogging caused by suspended solid particles is the most common plugging form of emitters. Water quality and emitter geometry are key aspects in clogging processes. Any suitable test procedure to assess the sensitivity of drippers to clogging should take into account the predominant factors that influence clogging and must reproduce the field conditions. This research set out to assess the performance and suitability of a laboratory clogging test procedure in order to validate a methodology and to provide scientific results that may support the standardization of a clogging test method. The evaluated methodology has been used by the IRSTEA laboratory since 1974 (Platform of Research and experiment on Science and Technology for Irrigation - PReSTI, formerly LERMI) and its contents are currently being discussed by the ISO TC23/SC18 committee. The aim is to define a standardized testing protocol to evaluate the sensitivity of emitters to clogging due to solid particles. Replications analyzing the clogging resistance of four models of emitting pipes were carried out in a laboratory. The clogging test procedure enabled an accurate assessment of the combinations of concentration and size of particles that caused clogging in each model of dripper. However, a significant variability in degree of clogging was identified when the results of replications for each model of dripper were compared. Several requirements, concerns, and improvements related to the clogging test protocol were discussed. [ABSTRACT FROM AUTHOR]