INNOVATION IN PASSIVE SAMPLING FOR VIRAL DETECTION IN WATER RESOURCES: TOWARDS ACCESSIBLE AND SENSITIVE MONITORING TECHNIQUES

Abstract

In response to the escalating challenges of viruses, this research focuses on advancing passive sampling methods to enhance public health security through improved viral surveillance in water resources. Effective surveillance hinges on the deployment of efficient sampling techniques that yield accurate and timely insights. Traditional sampling techniques, such as grab and composite methods, struggle to either capture temporal variations and often underestimate viral levels with grab samples or the logistical challenges with processing large volumes or significant costs and technical limitations of autosamplers in remote regions. This research focuses on leveraging various adsorbent materials to determine the most effective yet accessible method for capturing viruses in water resources. This work aims to overcome the constraints of current sampling methods by enhancing pathogen detection with novel passive sampling and innovative molecular techniques, enabling rapid, sensitive, and accessible viral monitoring. The use of accessible adsorbent materials like gauze, sponges, cheesecloth, and electronegative cellulose-nitrate membrane filters were evaluated for capturing SARS-CoV-2 from wastewater. These materials, especially electronegative membrane filters, demonstrated their potential for effective sampling of the virus in low-prevalence regions. However, bench-scale batch adsorption experiments revealed that these membrane filters align with pseudo-first-order kinetics reaching adsorption capacity within 24 to 48 hours. Also, the presence of total suspended solids in wastewater influenced the equilibrium adsorption dynamics of the filters, potentially due to the inhibitory effects of organic matter on subsequent analyses. Granular activated carbon (GAC) emerged as an enhanced adsorbent, in field-scale comparisons GAC adsorbed SARS-CoV-2 in wastewater more effectively than the electronegative filters. GAC's adsorption peaked at ~60 hours, suggesting its feasibility for longer deployments. The introduction of a multiplex RT-qPCR assay for simultaneous virus detection represents an advancement in surveillance, offering a rapid, economical alternative to other detection methods. The application of GAC-based passive sampling to a freshwater lake further confirmed the method's versatility and efficacy over grab sampling techniques for viral detection in diverse matrices. As such, GAC presents a scalable and convenient alternative for capturing viruses in water and wastewater, urging further investigation into adsorptive properties of GAC and further application for improved water safety.