Comparative Optimization and Equipment Development of Enrichment and Concentration Methods for SARS-CoV-2 in Wastewater from Inbound Flights
This study systematically compared three virus enrichment and concentration methods—polyethylene glycol (PEG) precipitation, aluminum salt coagulation, and centrifugal ultrafiltration—for detecting SARS-CoV-2 in high-turbidity, high-strength wastewater from inbound flights. The aluminum salt coagulation method exhibited the best overall performance, achieving an average recovery rate of 25.95% for SARS-CoV-2 pseudovirus, significantly higher than PEG precipitation (12.91%) and centrifugal ultrafiltration (0.22%) (P<0.05). Its detection limit reached 10 copies·mL⁻¹, whereas centrifugal ultrafiltration suffered severe membrane fouling, limiting detection to 1,000 copies·mL⁻¹. Considering the high pH buffering of flight wastewater, the aluminum salt method was optimized by adjusting pH to 6.00±0.4, employing rapid magnetic stirring, and reducing mixing time to 1 minute, yielding an average recovery of 27.56% (not significantly different from the original 25.95%, P>0.05). An automated enrichment device was developed based on the optimized method, reducing processing time per sample from 115 min to 60 min while maintaining comparable recovery and improved repeatability. Applied to 1,309 wastewater samples from inbound flights between January 2024 and May 2025, the average detection rate of SARS-CoV-2 was 45.45%, with trends consistent with national COVID-19 epidemiological data. The automated device demonstrates suitability for routine surveillance, providing technical support for port epidemic prevention.