SARS-CoV-2 (RNA) in municipal wastewater: hazards and opportunities

COVID-19 and sewage water

During the outbreak of the new COVID-19 viral disease it was discovered that the virus was also excreted in stools, that it ended up in the sewage, and that the viral RNA was detectable in municipal wastewater. This finding raised questions about the possible health hazards for people who were directly or indirectly exposed to sewage water – for instance: How long does the viral RNA signal remain intact in sewage water? And in sludge? Is it removed by the treatment processes? Does it get into receiving surface water through discharges or faulty connections? Does this present a health hazard? But the finding also offered opportunities to use sewage water to monitor the trends in the circulation of the virus among the population, making it possible to assess a whole city (or parts of it) in one go. Sewage water can thus supply valuable information for new policy measures. In order to implement wastewater surveillance as a reliable monitoring system, a good connection with the measurement of COVID-19 in the population needs to be established.

Validation of wastewater surveillance

Wastewater surveillance is a method that enables the early detection and monitoring of the introduction and development of the coronavirus.  The first experiences in the spring of 2020 demonstrated that wastewater surveillance could constitute a sensitive instrument. In order to implement wastewater surveillance to show the increase or decrease of infections, both the occurrence of COVID-19 in the population as well as of the viral RNA in the sewage network must be precisely characterised, and complemented with hydrodynamic modelling of the viral RNA in sewage water.

The present research focuses on the combination and validation of the underground and above-ground data.

The project combines four real-time monitoring systems in the Rijnmond region, namely:

1. Low-threshold testing through general practitioners.
2. Monitoring of clinical data via medical registers (syndrome surveillance).
3. Reports from virological laboratories.
4. Sewage water sampling.

By combining different techniques, which will be further developed and integrated into a unique monitoring system, we aim to define the optimal approach for the early and accurate detection of changes in COVID-19 cases in the population.