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Blog in the Time of Corona, and more potential benefits of wastewater

30 Apr 2020 8:59 PM | Natalie Love (Administrator)

Hi! We hope this finds you and yours safe and healthy during this time!

In this era of COVID, most drinking water professionals, wastewater professionals, and those that work in labs and other professions that provide assistance to maintain critical infrastructure have been classified as “necessary”, and most are required to go in to work, even if it is on a modified schedule. This requirement exposes many to vectors that those that are working from home are not exposed to. Most are not ‘on the front lines’, but their services keep permit requirements intact, water quality high,   and reassure the public that a new public health crisis does not evolve from failing water treatment. Remember, through all of the craziness your contribution matters, and we appreciate all that you do!

One positive thing about coronavirus; it does not ‘survive’ water treatment. There have been no cases of coronavirus in drinking water. Likewise, standard wastewater disinfection also renders coronavirus incapable of transmitting disease. Just imagine how much worse everything would be if this was not the case!

However, coronavirus is known to be present in wastewater. This can cause extra concern for wastewater operators, lab analysts, and others exposed to raw wastewater. Whether or not the coronavirus in wastewater can cause disease is still an open question that needs more study. Some studies show that coronavirus can survive for several days in wastewater, while other testing has shown that coronavirus is inactivated by going through a human gut. In any case, the good news is that no known case of COVID 19 is known to have been transmitted via wastewater. The CDC calls wastewater ‘low risk’ for COVID 19. The CDC, OSHA, and WEF all agree that the normal engineered and administrative measures, PPE, and hygiene measures protect wastewater workers sufficiently from COVID 19. While the risk is low, wastewater workers must exercise extra diligence at work, even while already taking added measures like wearing masks and social distancing. Additionally, WRRFs are not assured of being able to get sufficient PPE because of the higher world demand.

While we hope that wastewater does not have extra risks for workers, the coronavirus in wastewater has the possibility of becoming an important weapon in the fight against COVID 19. Because coronavirus is excreted in the feces and urine of affected persons, coronavirus in a sewer can be an early warning of COVID 19, and can be representative of the spread in the sewershed. It can also give important and timely information to public health decision-makers. This is known as Water Based Epidemiology (WBE), or Environmental Surveillance (ES). This is a developing field related to COVID 19 and has several hurdles before becoming relevant, but it is looking hopeful.

Researchers in The Netherlands are credited for being first to test wastewater for coronavirus. They found coronavirus in wastewater even before the first reported COVID infection in the sewershed. Thus, they established that coronavirus in the wastewater can be an early warning of COVID 19 in the population.

There are also currently several efforts to analyze levels of coronavirus in wastewater, and then to correlate those levels to an estimated number of affected people in the service area. Wastewater is a different and more complex matrix that those normally used in virology labs and is analytically challenging. Additionally there is an unknown distribution of the viral pieces between liquid and solid in the wastewater. Known levels of quantification are not yet known, but would have to be low enough to be able to compensate for the dilution of the virus in the wastewater in order to be useful. Already a researcher at Arizona State University (ASU) claims to be able to detect one affected individual in a population of 2 million. Others estimate 1-3 cases per 100,000 people. Additional problems on the analytical side are getting representative samples, developing rigorous QA/QC protocols, unknown matrix effects, and unknown fate and transport of coronavirus.

Once detected in wastewater, there are additional formidable challenges of correlating the level of coronavirus in the wastewater to the level of COVID infection in the population. This requires knowledge of the population, flow, temperature, time in the sewer, industrial/residential discharge ratios, the fecal shedding rate per person, and many other factors. It will apparently also require knowledge of the average size of human poop. (No need to set up a study for this though. A professor at MIT has already determined this. It is 200 grams.)

Despite the challenges, the promise of WBE/ES - that wastewater could give us both an early warning of, and an accurate measure of COVID in the population – is enticing. It could detect COVID 19 in a population before there have been any confirmed cases. It could indicate when a second or third wave is beginning. It would be faster than individual testing. It would include asymptomatic carriers and would be more representative of the spread of the disease than the current biased numbers that are low since they are hindered by testing availability. It would be specific to each sewershed, so response measures could better meet specific needs. It could be scalable; from the entire service area of a large WRRF down to a sewer from a single neighborhood, school, or assisted living facility. Testing would be cheap, the sample abundantly available.

The study of analytes in wastewater as they relate to current issues in the service population is not new. Illicit drugs, malaria, salmonella, other viruses, etc. have all been looked at in wastewater. Each case provides its own challenges, but they all confirm the interesting hidden value of wastewater, and its important relationship to its service area. And in this current crisis, it is another reminder of the important work that everyone in the water field does!

Please find references below. I also used some information from the Closing Ceremony of the WRF Virtual International Water Research Summit on Environmental Surveillance of Indicators of COVID 19 in Sewersheds, April 30, 2020. Please let me know if you would like more information, or if you have an interesting addition!

Rich MacAlpine is a Laboratory Supervisor at Metro Wastewater Reclamation District. 





Arizona State University. "Novel coronavirus detected, monitored in wastewater." ScienceDaily. ScienceDaily, 23 April 2020. <www.sciencedaily.com/releases

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