Wastewater-Based Epidemiology: Detection of SARS-CoV-2 RNA in Different Stages of Domestic Wastewater Treatment in Santa Fe, Argentina

Abstract

The COVID-19 pandemic affected human life at every level. In this study, we analyzed genetic markers (N and ORF1ab, RNA genes) of SARS-CoV-2 in domestic wastewaters (DWW) in San Justo City (Santa Fe, Argentina), using reverse transcription-quantitative real-time PCR. Out of the 30 analyzed samples, 30% were positive for SARS-CoV-2 RNA. Of the total positive samples, 77% correspond to untreated DWW, 23% to pre-chlorination, and no SARS-CoV-2 RNA was registered at the post-chlorination sampling site. The viral loads of N and OFR1ab genes decreased significantly along the treatment process, and the increase in the number of viral copies of the N gene could anticipate, by 6 days, the number of clinical cases in the population. The concentration of chlorine recommended by the WHO (≥ 0.5 mg L^-1 after at least 30 min of contact time at pH 8.0) successfully removed SARS-CoV-2 RNA from DWW. The efficiency of wastewater-based epidemiology (WBE) confirms the need to control and increase DWW treatment systems on a regional and global scale. This work could contribute to building a network for WBE to monitor SARS-CoV-2 in wastewaters during the pandemic waves and the epidemic remission phase.

Supplementary information: The online version contains supplementary material available at 10.1007/s11270-022-05772-w.

Keywords: Domestic wastewater treatment; Reverse transcription-quantitative real-time PCR; SARS-CoV-2 RNA; Wastewater-based epidemiology.

Fig. 1

Study area. A Location of the WWTP. B Sampling sites at the different stages of the treatment (S1, S2, and S3)

Fig. 2

Relationship between daily active cases of COVID-19 and the number of genetic copies of SARS-CoV-2 100 mL.⁻¹ of DWW (principal Y-axis) and positivity of DWW samples for both genetic markers, N (yellow squares), and ORF1ab (green triangles)