COVID-19 in Wastewater: A new frontier for research

Despite the few days remaining until the long-awaited end of this unprecedented year, we unfortunately know that there is no magic spell that will make the COVID-19 pandemic disappear when the clock strikes midnight. We are now busy waiting for an effective worldwide vaccination campaign that will allow us to go back to our daily routines – what we used to call “normality”-, while governments continue to contend with a relentless spread of the virus and its harsh impact on society. But, since the 2019 novel coronavirus SARS-CoV-2 has come to stay, it got me thinking: what will happen next?

My name is Sara Feijoo Moreira, PhD Candidate at KU Leuven investigating in the European H2020 MSCA-ETN InnovEOX project and this is my personal contribution to the InnovEOX blog series. Spoiler alert: I do not have the answer to that question. Nonetheless, what I do know is that science and research are the key to knowing more about this virus and developing strategies to mitigate its effects. In order to live with this pathogen in the coming years, we need to learn how to keep it under control, not only in terms of medical treatment, but also in all other areas where it is present.  One of these areas is water and wastewater treatment, which is very much close to the core of our InnovEOX focus, as our work is aimed at addressing the contamination of water resources by emerging contaminants.

Figure 1. Survival time of SARS-CoVs (squares) and other enveloped viruses (circles) for 90% inactivation (T90) in water samples including: deionized and sterilized tap water (RO + UV tap); tap water after chlorine removal (Dechlor. tap); phosphate buffered saline solution (PBS); lake water and human excretions (urine and stool); pasteurized (Past.) wastewater (WW) after settling; past. raw WW; primary or secondary effluent (Pri., sec. eff); and raw WW [1].

Previous studies have reported that coronaviruses (i.e., SARS-CoVs) can be found in wastewater, originating primarily from the excretions of infected patients, and remain infectious for several days after entry into the sewage system (Figure 1) [1─4]. The novel SARS-CoV-2 has already been detected in wastewater up to concentrations above 106 gene copies per liter [4─6], and similarly to other SARS-CoVs, its presence in aquatic environments is determined by multiple factors, including temperature, light exposure, organic content, pH, and the occurrence of chemicals, disinfectants and other microorganisms [1, 2, 4]. Nonetheless, several studies have shown that according to the survival rate of SARS-CoVs, these pathogens are highlighted as persistent [4, 7─9] and their transport to the urban water cycle (Figure 2) becomes a potential risk to human health [1, 9].

Coronavirus-containing water can affect humans, not only by drinking it directly, but also through its use for agricultural and recreation purposes, or even its aerosolization in the droplets from shower heads [1, 2]. It has been postulated that treated water effluents may therefore be a route of infection for SARS-CoV-2 outbreaks, especially given the higher viral load in wastewater during pandemic times and the fact that there is no evidence that conventional wastewater treatment technologies (which rely on disinfectants such as chlorine and ozone) can provide a complete virus removal [1, 2, 4].

Figure 2. Overview of potential SARS-CoV-2 dissemination in industrialized countries [1].

Even though the primary route of SARS-CoV-2 infections is through oral and nasal secretions when in close contact with an infected patient, these findings put in the spotlight the importance of investigating other pathways of indirect transmission. Developing more effective viral disinfection measures, both in drinking water and in sewage treatment plants, is another crucial procedure to prevent further spreads. Furthermore, it is necessary to improve our current urban infrastructure with surveillance techniques specifically aimed at coronaviruses, so that the presence in the urban water cycle can be characterized and kept under control, not only because of the challenge we face today, but also in light of possible future viral outbreaks.

 

References

[1] A. Bogler, A. Packman, A. Furman, A. Gross, A. Kushmaro, A. Ronen, C. Dagot, C. Hill, D. Vaizel-Ohayon, E. Morgenroth, E. Bertuzzo, G. Wells, H. R. Kiperwas, H. Horn, I. Negev, I. Zucker, I. Bar-Or, J. Moran-Gilad, J. L. Balcazar, K. Bibby, M. Elimelech, N. Weisbrod, O. Nir, O. Sued, O. Gillor, P. J. Alvarez, S. Crameri, S. Arnon, S. Walker, S. Yaron, T. H. Nguyen, Y. Berchenko, Y. Hu, Z. Ronen and E. Bar-Zeev, “Rethinking wastewater risks and monitoring in light of the COVID-19 pandemic,” Nature Sustainability, vol. 3, pp. 981-990, 2020.

[2] V. Naddeo and H. Liu, “Editorial Perspectives: 2019 novel coronavirus (SARS-CoV-2): what is its fate in urban water cycle and how can the water research community respond?,” Environmental Science: Water Research & Technology, vol. 6, no. 5, pp. 1213-1216, 2020.

[3] D. A. Larsen and K. R. Wigginton, “Tracking COVID-19 with wastewater,” Nature Biotechnology, vol. 38, pp. 1151-1153, 2020.

[4] M. Kitajima, W. Ahmed, K. Bibby, A. Carducci, C. P. Gerba, K. A. Hamilton, E. Haramoto and J. B. Rose, “SARS-CoV-2 in wastewater: State of the knowledge and research needs,” Science of The Total Environment, vol. 739, p. 139076, 2020.

[5] G. Medema, L. Heijnen, G. Elsinga, R. Italiaander and A. Brouwer, “Presence of SARS-Coronavirus 2 RNA in Sewage and Correlation with Reported COVID-19 Prevalence in the Early Stage of the Epidemic in The Netherlands,” nvironmental Science & Technology Letters, vol. 7, pp. 511-516, 2020.

[6] W. Randazzo, P. Trunchado, E. Cuevas-Ferrando, P. Simón, A. Allende and G. Sánchez, “SARS-CoV-2 RNA in wastewater anticipated COVID-19 occurrence in a low prevalence area,” Water Research, vol. 181, p. 115942, 2020.

[7] L. Casanova, W. A. Rutala, D. J. Weber and M. D. Sobsey, “Survival of surrogate coronaviruses in water,” Water Research, vol. 43, no. 7, pp. 1893-1898, 2009.

[8] T.-T. Fong and E. K. Lipp, “Enteric Viruses of Humans and Animals in Aquatic Environments: Health Risks, Detection, and Potential Water Quality Assessment Tools,” Microbiology and Molecular Biology Reviews, vol. 69, no. 2, pp. 357-371, 2005.

[9] K. R. Wigginton, Y. Ye and R. M. Ellenberg, “Emerging investigators series: the source and fate of pandemic viruses in the urban water cycle,” Environmental Science: Water Research & Technology, vol. 1, pp. 735-746, 2015.

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