Wastewater surveillance is a noninvasive and flexible approach for monitoring various public health concerns at the community level. Electronegative membranes are a commonly used passive sampling material to collect viral material in a wastewater stream. Although passive sampling has been evaluated in the field, a clear relationship between the adsorption kinetics of viruses and various factors, such as exposure time, pH, and concentration of viral material, are difficult to quantify. Pepper Mild Mottle Virus (PMMoV) is a plant pathogen common in the human diet and is used as a biomarker in wastewater surveillance. In this study, PMMoV was extracted from Tabasco sauce to study the adsorption kinetics of PMMoV onto cellulose nitrate membranes in a controlled environment. Dynamic Light Scattering (DLS) was used to approximate the length and width of the rod-shaped PMMoV particles and is proposed as an effective characterization tool when accounting for the spherical-particle assumption of DLS measurements and the shape of the particles using the Full Width Half Maximum approach, as opposed to taking the maximum when analyzing peaks. Pseudo second-order kinetics was found to best describe the adsorption of PMMoV onto membranes. Concentration influenced adsorption, and a higher concentration of PMMoV yielded greater initial uptake and higher equilibrium concentration (qe*k2=0.343 h-1 for the higher concentration and qe*k2=0.199 h-1 for the lower concentration). However, pH (pH 5 versus pH 7) did not have a significant influence on adsorption, and there was no noticeable difference in initial uptake and equilibrium concentration with a decrease in pH (qe*k2=0.126 h-1 for pH 7 and qe*k2=0.169 h-1 for pH 5). This work highlights the significance of concentration for recovery efficiency and notes the various compounding factors besides pH that can impact adsorption, which are important considerations for the interpretation of passive sampling data and, ultimately, for the development of a robust and quantitative method.
Niro et al. (2026) studied this question.