Experimental Study of PhiX174 Resuspension from Mobile Bed Sediment

PhiX174 (or φX174) is a spherical single-stranded DNA bacteriophage used as a surrogate to study viral enteric pathogens in the environment. The resuspension of viral pathogen from bed sediment in irrigation canals impairs the quality of overlaying water and can result in the contamination of produce. We conducted a series of laboratory experiments to evaluate the resuspension of PhiX174 from bed sediment in an open channel flume. Different flow conditions (e.g., flow rate, velocity, shear stress) and three types of sediment mixtures (i.e., loam, sand, sandy loam) were investigated. Results revealed that the resuspension rate increases with the dimensionless bed shear stress. Based on these results, for the first time, we proposed two models to correlate the concentration of PhiX174 with the dimensionless bed shear stress for different sediment. One model was proposed for sandy loam and loam, was verified favorably by the experimental data, and yielded a Nash-Sutcliffe efficiency coefficient (NSE) of 0.71 and R2 value of 0.72. The other model was proposed for sand, with NSE of 0.20 and R2 of 0.26. The application of these models also indicated viruses are more easily resuspended from sand than sandy loam or loam sediments. The models shed a light for studying the correlation between the viruses in water and sediment and will benefit the management of irrigation water quality.