Development of a powdered activated charcoal sodium alginate hydrogel bead concentration method for detecting viruses in wastewater†

Existing techniques for concentrating viruses from wastewater are often time consuming, costly, and usually involve cumbersome laboratory methods, limiting their practical application for routine use. As such, the need for simpler concentration methods that do not forfeit efficacy are crucial for permitting more accessible detection of viruses from wastewater. This study introduces a rapid concentration method using powdered activated charcoal sodium alginate (PAC-NaA) hydrogel beads, optimized for capturing viruses from wastewater. Through scanning electron microscopy and bench-scale experiments, we optimized hydrogel bead formulation and identified a Tween®20-based buffer as the most effective elution buffer for recovering SARS-CoV-2 from the hydrogel beads. Kinetic adsorption parameters were also evaluated, establishing a 5 min exposure duration for maximum viral recovery. Model fitting of the experimental data indicated that the adsorption process adheres to a non-linear pseudo-second-order model, indicative of physiochemical adsorption mechanisms likely facilitating viral capturing from wastewater. Additionally, successful detection of endogenous SARS-CoV-2 and Adenovirus was achieved using the PAC-NaA hydrogel concentration method. The advantages of this approach lie in its adaptability and simplicity, as hydrogel beads can be modified to enhance viral adsorption efficiency in various environmental contexts.