Single Collector Attachment Efficiency of Colloid Capture by a Cylindrical Collector in Laminar Overland Flow

Abstract

Little research has been conducted to investigate the fate and transport of colloids in shallow overland flow through dense vegetation under unfavorable chemical conditions. In this work, the single collector attachment efficiency (α) of colloid capture by a simulated plant stem (i.e., cylindrical collector) in laminar overland flow was measured directly in laboratory flow chamber experiments. Fluorescent microspheres of two sizes were used as experimental colloids. The colloid suspensions flowed toward a glass cylindrical rod installed in a small size flow channel at different laminar flow rates. Different solution ionic strengths (IS) were used in the experiments to simulate unfavorable attachment conditions. Our results showed that α increased with IS and decreased with flow velocity. Existing theoretical and empirical models of colloid attachment efficiency for porous media were used to simulate the experimental measurements in α and found to fall short in matching the experimental data. A new dimensionless (regression) equation was proposed that predicts the α of colloid capture by a cylindrical collector in laminar overland flow with reasonable accuracy. In addition, the equation was also effective in predicting the attachment efficiency of colloid deposition in porous media.

Spontaneous Detachment of Colloids from Primary Energy Minima by Brownian Diffusion

“…These theoretical results provide plausible explanations for a distribution of colloid detachment rate coefficients observed in the columns experiments conducted over long-time periods [ 69 , 70 ]. However, it should be noted that the previous study employed the balance of hydrodynamic and adhesive torques as the sole criteria for determining detachment of colloids from primary minima, similar to previous studies [ 3 , 5 , 15 , 29 , 31 , 32 , 52 , 71 , 72 ]. Our results indicate that this approach could underestimate the detachment of colloids from primary minima because the spontaneous detachment by Brownian diffusion (i.e., the slow detachment stage) was not taken into consideration.…”

Release and Removal of Microorganisms from Land-Deposited Animal Waste and Animal Manures: A Review of Data and Models

“…Plants and litter can decrease runoff partitioning and can retain manure-borne bacteria on the surface; thus, accumulating microorganisms at an earlier stage of release or runoff can serve as a source for microbial release at a later time . Surface filtration of colloidal contaminants (e.g., bacterial indicators and pathogens) by vegetation is controlled by the physical contact processes and chemical attachment processes that are interacting during laminar overland flow (Wu et al, 2012;Wu et al, 2014). Colloidal attachment efficiencies are affected by Van der Waals attractive forces, electrostatic double-layer forces, and hydrodynamic forces (Wu et al, 2012;Wu et al, 2014).…”

“…Surface filtration of colloidal contaminants (e.g., bacterial indicators and pathogens) by vegetation is controlled by the physical contact processes and chemical attachment processes that are interacting during laminar overland flow (Wu et al, 2012;Wu et al, 2014). Colloidal attachment efficiencies are affected by Van der Waals attractive forces, electrostatic double-layer forces, and hydrodynamic forces (Wu et al, 2012;Wu et al, 2014). Organic matter that coats vegetation has been shown to play an important role in colloidal attachment efficiency as well (Wu et al, 2014).…”

Colloidal transport and deposition through dense vegetation

“…Typically, it is modeled using first-order deposition kinetics (Kretzschmar et al, 1997;Molnar et al, 2015). Classical filtration theory, used to explain the colloid deposition mechanism in porous media (Jin et al, 2018), is also appropriate to describe the retention of colloids by dense vegetation (Wu et al, 2012;Yu et al, 2012Yu et al, , 2019. In this context, the deposition rate coefficient ( ) is the key parameter quantifying colloid filtration by vegetation.…”

“…Reported studies on plant filtration of colloids in the literature involve small-scale setups, such as the scale of single plant stem or several centimeters of vegetation (Wu et al, 2011;Wu et al, 2012;Wu et al, 2014;Yu et al, 2012;Yu et al, 2013).…”