Surveillance of SARS-CoV-2 in sewage and wastewater treatment plants in Mexico. (April 2021)

• Record Type: Journal Article
• Authors: Carrillo-Reyes, Julián; Barragán-Trinidad, Martín; Buitrón, Germán
• Is Part Of: Journal of water process engineering. Volume 40(2021)
• Publication Date: 2021-04
• Subjects: COVID-19 -- SARS-CoV-2 -- Wastewater -- Sewer system -- Wastewater-based epidemiology; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2020.101815
• Languages: English
• ISSNs: 2214-7144

Abstract

Graphical abstract: Highlights: First report of SARS-CoV-2 RNA in sewage in Mexico. Surveillance in WWTP and two RNA-concentration methods were evaluated. The solid fraction from sewage plays a crucial role in adsorbing viral RNA. Adsorption method resulted in higher RNA titration values than with ultrafiltration. The surveillance of RNA in WWTP matched the cumulative COVID-19 cases. Abstract: The SARS-CoV-2 virus causing COVID-19 is spread in sewage by the stool of infected individuals, and viral material in sewage can be quantified using molecular tools. This study aimed to monitor the presence of SARS-CoV-2 RNA in sewage in Mexico based on RdRP, S, and N gene analysis. The influent, effluent, and activated sludge from two domestic wastewater treatment plants (WWTP) were evaluated from the early stage of the epidemic to July 2020. Additionally, sampling points in sewer systems were examined, comparing two different RNA-concentration methods: centrifugal ultrafiltration and adsorption-based methods. The adsorption method resulted in RNA titration that was two orders of magnitude higher than with ultrafiltration (up to 3.38 log10 copies RdRP gene/mL of sewage). The surveillance of SARS-CoV-2 RNA in the influent of two WWTP correlated with the cumulative COVID-19 cases in Queretaro city. The higher RNA level in secondary sludge compared to influent suggests that viral RNA becomes concentrated in activated sludge. This result supports SARS-CoV-2 RNA removal in WWTP, where all effluent samples were negative for virus quantification. This work proves that wastewater-based epidemiology is a very valuable tool in developing countries where diagnostic tests for COVID-19 are limited.