Evaluation of Thirty-Eight Models of Drippers Using Reclaimed Water: Effect on Distribution Uniformity and Emitter Clogging

Abstract

Emitter clogging is a problem in drip irrigation systems, and it is accentuated when using reclaimed water. The objective of this work was to evaluate the different commercial models of drippers used for irrigation with reclaimed water in greenhouse horticultural crops. Thirty-eight commercial emitter models were selected. The selection was based on recommended models from different irrigation installation companies and manufacturers for this type of water. These emitters had different types of pipeline insertion (inter-line, in-line, and on-line) and different pressure compensation (compensating and non-compensating pressure). The emitter models were analyzed in the laboratory, determining the manufacturing variation coefficient (Cv) and the emitter equation (Ee), and subsequently two consecutive tests were established in the greenhouse, with a period of irrigation inactivation between tests, as well as different reclaimed water qualities. The reclaimed water was regenerated urban wastewater from the city of Almería. Distribution uniformity coefficient (DU) and clogging of the emitter (Ec) were evaluated in the greenhouse tests. Of the 38 models analyzed, only one of them did not comply with the International Organization for Standardization (ISO) standard, providing a Cv greater than 0.07. At the commencement of the greenhouse trial (0 h of irrigation), 14 dripper models performed with an excellent DU, above 95%, and all emitter models presented a DU above 85%. At the end of the second greenhouse trial (206 h of irrigation), three models recorded a DU of less than 85%. The application of reclaimed wastewater produced events of clogging and reducing uniformity in the studied models. On-line pressure-compensating emitter models had the worst performance. The irrigation inactivation period produced an improvement in uniformity values. By improving the quality of reclaimed water, all types of emitters showed a better performance during the irrigation season. Notably, pressure-compensating emitter models even showed some cleaning capacity, because their clogging was reduced in the second trial.