Investigating the Clogging Mechanism in Membrane Discharge Irrigation Systems Using Reclaimed Water: A Comparative Case Study of Trace Quantity Irrigation and Moistube Irrigation

Abstract

Trace quantity irrigation (TQI) and moistube irrigation (MTI) are membrane discharge irrigation (MDI) systems designed to minimize water use and prevent clogging. When laboratory-prepared reclaimed water (similar to the China Class I-B standard) was used, emitter clogging (EC) occurred faster in the TQI, escalating within 216 h, compared to 312 h for the MTI. Analysis of dry weight (DW), extracellular polysaccharides (PSs) and proteins (PNs) in different parts of the irrigation pipes revealed that the PS and PN contents contributed to the EC, with the end part being the most affected. High-throughput sequencing identified Proteobacteria as a key factor in clogging, with Aquabacterium being dominant in TQI and Pseudomonas in MTI, whereas Methylophilus was common to both, suggesting that aerobic and anaerobic alternations exist in the irrigation pipe. Computational fluid dynamic (CFD) simulations indicated that the TQI had a faster flow velocity and greater water shear, leading to greater DWs in MTI (1.79–2.27 times higher than the TQI) but similar PS (1.06–1.47 times) and PN (0.87–1.03 times) levels. To manage clogging, MDI systems should apply chlorination with pressure flushing before clogging intensifies, adjusting the flushing duration according to the water quality.