Characteristics and deposition pattern of clogging material on cylindrical drip emitters was studied using nondestructive methods of evaluation. Two sets of four cylindrical emitter samples were collected from farm lands. One set of sample emitters was analyzed using Computed Tomography (CT). Other set was dissected and the clogging material extracted was analyzed using Energy Dispersive X-Ray Fluorescence (EDXRF) and X-Ray Diffraction (XRD). CT scans revealed the geometric properties of emitters and the spread of clogging material on the emitter surface. EDXRF analysis found statistically significant inverse relationship between the proportion of physical clogging and chemical clogging materials. XRD analysis indicated presence of physical and chemical clogging materials in their crystalline forms. Emitters having transverse flow path and the boundary optimized with curvature found with the least deposition of physical clogging materials. Corresponding proportion of chemical clogging (as Ca) was found to be much higher. All the samples were found with more clogging material closer to the outlets. Efforts to optimize emitter geometry shall also take into account the outlet area optimization and chemical clogging for obtaining best results.

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Various new and innovative methods of prevention and treatment of emitter clogging were demonstrated by researchers in recent years. A total of nine such innovative approaches were reviewed, classifying them under three broad categories, viz., physical, chemical and biological methods. Though flushing of laterals is a known method, it was found that increasing its frequency and at higher pressures improved the emission rate and uniformity of the emitters significantly. When Treated Waste Water (TWW) is used for irrigation, flushing with fresh water after every five irrigations effectively removed the emitter clogging. Among the various physical methods reviewed, use of MERUS ring, application of pulsating pressure with triangular wavefront and ultrasound treatment were found to be effective in removing composite clogging problem in drip emitters. Among the chemical methods, fertigation using Urea Phosphate (UP) at low concentrations for longer periods reduced the pH of irrigation water and contributed to the removal of chemical precipitates from the lateral pipes and emitters. Use of antagonist Bacillus bacterial strains helped in removing not only CaCO3 precipitation but also biofouling due to the use of TWW in the drip systems. However, this method needs to be further developed and optimized for its effectiveness and replicability.

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