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SARS-CoV-2 Virus in Wastewater: Situation Brief Information for the Wastewater Treatment Industry and Municipal Governments

This article provides a cursory review of current literature relevant to the municipal wastewater treatment community and our present understanding of their unique risks and opportunities.

What You Need to Know

‣ Human waste from people with Covid-19 contains the virus SARS-CoV-2 that causes the disease. This viral load may remain for several days after a patient’s respiratory tract tests negative for the virus.

‣ During the pandemic, huge viral loads are present in municipal wastewater systems.

‣ Data support the notion that the virus is viable in the environment for prolonged periods under some conditions, facilitating environmental contamination and potential transmission from direct exposure to untreated waste, including the inhalation of aerosols.

‣ Standard occupational safety measures are thought to be effective in protecting against the corona virus in sewage; however, municipal wastewater facilities are advised to:

  • Review occupational safety measures in light of this new information and uncertainty, adjusting measures as required;
  • Ensure staff have adequate personal protective equipment (PPE); and,
  • Promote awareness among facility operators and the use of PPE to avoid inadvertent contact with sewage, including the inhalation of very fine particles suspended in the air.

The Opportunity

‣ Analysis of sewage at municipal wastewater facilities enables local governments to monitor the sewage to detect the relative presence of the disease in a population, including asymptomatic carriers, and to act as an early warning system for resurgent out-breaks.

‣ This information will inform healthcare and economic mitigation efforts and policy.

Research Gaps

‣ Research to determine the potential for fecal–oral transmission of SARS-CoV-2 and the viability of the virus in various environmental conditions.

‣ Research to quantify the presence SARS-CoV-2 in sewage and calibrate surveillance data, enhancing its utility as a tool in the fight against this latest coronavirus and its circulation.

The Bigger Problem

‣ While typical disinfection practices of wastewater treatment facilities effectively eliminate the viral load in treated wastewater before it is returned to the environment, populations without adequate sanitation may face increased risk of transmission.

‣ Populations with inadequate water and wastewater treatment may serve as a refuge for the virus, potentially sustaining the pandemic.

Purpose

This article is somewhat of a divergence from my recent writings on sustainability, innovation and water treatment. While consistent in subject matter, its form and purpose are markedly different. My writings generally focus on a specific strategic or operational topic related to water treatment, with key insights illustrated using case studies presented in the classic “situation – complication – resolution” framework. This is not that.

I write to promote awareness and an abundance of caution among wastewater treatment (WWT) professionals and municipal treatment facilities regarding SARS-CoV-2, the virus that causes the disease Covid–19.

I also write to highlight potential opportunities for municipal WWT facilities and industry professionals to partner with researchers and contribute to the information and tools that will enable our communities to eventually emerge from our shelter-in-place economy – gathering data and developing models that will enable municipal WWT facilities to serve as distributed network for monitoring changes in the abundance of the SARS-CoV-2 virus in our communities.

Lastly, I write to highlight a global issue that may threaten the already tenuous health of the billions of people living without adequate sanitation, and the potential for these vulnerable, underserved populations to act as an endemic refuge for the virus, perpetuating the risk of resurgent outbreaks.

All of these subjects are in need of additional research and collaboration to better understand and quantify the risks and opportunities we face and our potential contribution in charting a course towards “resolution.”

Context

I was writing an article on emerging contaminants¹ and the relative ability of various wastewater disinfection methods to remove the broad array of endocrine disruptors, pharmaceutically active compounds, personal care products and the hormones in our water supply. It’s a worrying gap in our municipal water treatment regulations, one that every community relying only on traditional biological treatment, without advanced processes such as granular activated carbon and/or ozonation, should be aware of – particularly since proven mitigation measures exist.

In the course of my research, a Brazilian researcher sent me a Technical Notice published on March 30, 2020 regarding another type of emerging contaminant.² The Notice promotes awareness of the potential for transmission and infection from contaminated wastewater and an abundance of caution among wastewater practitioners until more research is undertaken on the viability of this transmission pathway. It also raises another concern – the significant number of people living without adequate sanitation and the effect this pandemic may have on them.

"As a consequence, the spread of Sars-CoV-2 in the environment and the infection of the most vulnerable part of the population, which does not have access to adequate basic sanitation infrastructure, may increase," says the technical note, which is signed by Carlos Chernicharo, a professor at the Federal University of Minas Gerais (UFM) associated with the School's Department of Sanitary and Environmental Engineering Department, and colleagues César Mota and Juliana Araújo, who authored the notice.

The content presented herein, along with additional sources and research, is a summary of preliminary articles and published notices – a cursory review of current information. The case study featuring Brazil serves to highlight additional concerns for populations living without adequate sanitation – the effects of the pandemic on them, and in-turn, their potential effects on the pandemic.

The Evolving Situation

On February 19, 2020, the Lancet Gastroenterol Hepatol Magazine published an advance article from its forthcoming April edition on the novel corona virus that stimulated significant discussion among medical and water researchers and practitioners alike.

The authors remind us that coronaviruses are a family of single-stranded, enveloped RNA (ribonucleic acid) viruses and note that SARS-CoV-2 – the virus that causes Covid-19 – is 82% similar to SARS-CoV, the virus associated with the 2002-03 SARS pandemic. Of greater concern was the potential for viable viral RNA of SARS-CoV-2 to be present in human feces, as is the case with other SARS viruses. For example, during the 2002-03 SARS-CoV outbreak, researchers detected viable viral RNA in the digestive tract and feces of patients from the fifth day of illness onwards for up to 30 days – even after the respiratory tract tests negative.

The authors note that viable SARS-CoV RNA is also known to occur in sewage water for days, with longevity inversely correlated with the temperature of the sewage; that is, the higher the sewage temperature, the shorter the time the virus remains viable in the environment. For example, experiments carried out with sewage from hospitals in Beijing during the 2002-03 SARS pandemic demonstrate its ability to remain infectious for up to 14 days at 4°C; up to five days in conditions of 22–25°C and 40–50% relative humidity; and, up to two-weeks after drying. Similarly, the authors note that the Middle East respiratory syndrome coronavirus (MERS-CoV) also actively replicates within the gastrointestinal tract and remains viable in environmental conditions with low temperatures and humidity. The data suggest that the gastrointestinal tract may even be the primary source of infection. Thus, the researchers hypothesized that these characteristics may also be true for the latest virus, SARS-CoV-2.

The potential for the SARS-CoV-2 virus to also be present in human waste and viable in the environment for prolonged periods under some conditions raised concern for those working in municipal wastewater treatment facilities, as this is a potential pathway for fecal–oral transmission from environmental contamination and direct exposure to untreated waste, including the inhalation of aerosols – droplets of contaminated sewage generated during aeration and other common processes used in the biological treatment of wastewater.

In short, although unproven, the viability of SARS-CoV and MERS-CoV under various conditions and their prolonged presence in the environment suggests the potential for the SARS-CoV-2 virus to be transmitted via inadvertent contact with sewage, including the inhalation of very fine particles suspended in the air.

Human waste from people with Covid-19 contains the virus SARS-CoV-2 that causes the disease.

On March 5, 2020, the New England Journal of Medicine published a brief, case report documenting the first case of Covid-19 in the United States, including the presence of SARS-CoV-2 RNA in the patent’s feces. Several other reports published since then confirm persistent fecal viral shedding of SARS-CoV-2 in the stool samples of patients in China.

During the Pandemic, Huge Viral Loads are Present in Municipal Wastewater of an infected Population.

On March 29, 2020, researchers from the Water Research Institute, Netherlands, published the first report of SARS-CoV-2 in sewage, documenting its presence in multiple domestic WWT facilities during the early stages of the Covid-19 epidemic in that country.

Specifically, the authors detected an abundant viral load in six of the seven municipals wastewater treatment facilities sampled. Preliminary research quantified the viral load – 10⁷ RNA copies/gram feces were measured one week after symptom onset and decreased to 10³ RNA copies/gram three weeks after symptom onset, with viable Sars-CoV-2 present in samples with a larger amount of viral RNA.

Although it is thought that municipal wastewater is unlikely to become a primary pathway for SARS-CoV-2, the authors note that “the increasing circulation of the virus in the population will increase the virus load into the sewer systems of our cities” and highlight the need for additional “information about the occurrence and fate of this new virus in sewage to understand if there is no risk to sewage workers.”

To clarify, there is still no scientific evidence to prove that the presence of the virus in sewage can cause Covid-19 by inadvertent ingestion, inhalation of aerosols containing droplets of contaminated sewage or even penetration through the mucous membranes of the eyes or openings in the skin. Nonetheless, the data are limited and the risk associated with uncertainty is such that researchers and practitioners alike promote an abundance of caution until more information is known about the potential risk to those operating WWT facilities.

Data support the notion that the SARS-CoV-2 virus may be viable in the environment for prolonged periods under some conditions, facilitating transmission from direct exposure to untreated waste and environmental contamination.⁴

Review Occupational Safety Measures

Professor Carlos Chernicharo, coordinator of the Federal University of Minas Gerais’s National Institute of Science and Technology in Brazil underscores the importance of care required by workers and researchers in the sector.

“Professionals who work in the sanitary sewage area, such as those who operate collection networks and treatment plants and researchers who handle sewage samples, cannot give up measures – such as the use of personal protective equipment to avoid inadvertent ingestion of sewage, even the ingestion of aerosols [very fine solid or liquid particles suspended in the air] – to avoid contamination.”

While standard occupational safety measures are thought to be effective in protecting against coronavirus and other pathogens present in the sewage, I echo my colleagues in promoting caution in light of uncertainty. Specifically:

  • Municipal wastewater treatment (WWT) facilities should consider reviewing current occupational safety measures and adjust accordingly, ensuring staff have adequate personal protective equipment (PPE); and,
  • Operators of municipal wastewater treatment facilities should be mindful of the potential for transmission and are advised to use PPE to avoid inadvertent contact with sewage, including the inhalation of very fine particles suspended in the air.

My synopsis of the current situation is this:

  • The fact that there are viruses in water may not necessarily present an acute health problem for WWT workers; however, if inadvertent ingestion is a viable pathway for infection, the virus is more likely to be inhaled as a source of infection.
  • There can be tremendous aerosol formation in a WWT plant from different methods of aeration – bubbles rising out the water from diffused or jet systems, surface mixers churning water and atmospheric air, as well as cascade systems, brush rollers and many other traditional aeration systems.

Chris Milligan, CEO and Chief Engineer at BlueInGreen – a water cleantech company based in Fayetteville, AR – sums up the current situation.

“The issue at the moment is uncertainty. We just don’t know the risks, so municipal WWT workers may want to err on the side of caution. If research finds that ingestion is a pathway for the disease, then technologies that don’t splash or bubble up - like what we provide at BlueInGreen - will be of paramount importance.”

An Opportunity to Contribute

The publications from the New England Journal of Medicine, the Netherlands Water Research Institute, the Lancet Gastroenterol Hepatol Magazine and the various technical notices and articles point to a common opportunity for municipal governments, wastewater professionals and researchers to collaborate and contribute to the monitoring and management of the SARS-CoV-2 pandemic.

Domestic wastewater treatment is a local, geographically constrained service, supporting a specific population. That is, the population served by a municipal wastewater treatment facility is defined by the municipality’s physical collection infrastructure – its sewer systems. Since, the virus may be detected in sewage, even when the COVID-19 prevalence is low and before Covid-19 cases are reported in a population, “sewage surveillance” may be a sensitive tool to monitor the circulation of the virus in a population.

As novel as “sewage surveillance” may sound to some, it is a proven approach used in poliovirus surveillance as well as monitoring antibiotic-resistant bacteria and use of illicit and prescription medications.

On April 5, 2020, researcher published findings demonstrating the potential value of this approach.⁵ Samples recently collected from a WWT facility serving a large Massachusetts metropolitan area contain more SARS-CoV-2 in the sewage than what one would expect, given the confirmed number of cases reported in the area. This suggests that many more people are likely infected with Covid-19 than reported in the area.

Although the preliminary data from the researchers demonstrate that sewage surveillance can detect the presence of SARS-CoV-2 in sewage samples when the observed COVID-19 prevalence is as little as 1.0 confirmed case in 100,000 people, more data under a variety of conditions is required than just the limited number of locations studied thus far.

  • Research to quantify the presence SARS-CoV-2 in sewage and calibrate surveillance data, enhancing its utility as a tool in the fight against this latest coronavirus and its circulation.

With better information, WWT facilities may function as an early warning system, monitoring the presence and abundance of the virus within a community, including asymptomatic carriers.

Mobilization

On April 13, 2020, the Brazilian Association of Sanitary and Environmental Engineering’s Thematic Chamber of Sewage Treatment, published a Technical Notice on the coronavirus and sewage systems in Brazil, emphasizing caution while outlining a course of action.

In Brazil, research is underway to help track the presence of SARS-CoV-2 in municipal sewage systems as a method for assessing the degree of contamination within population. The premise – that sewage surveillance can broadly cover the presence of the coronavirus and thus be a complementary tool to conventional testing carried out on people, has significant merit for several reasons:

  • Traditional testing is limited and may remain so for some populations;
  • Many people are likely infected, untested and asymptomatic, spreading infections; and,
  • Sewage surveillance may be a long-term method of monitoring communities for a resurgence of the disease, potentially alerting communities as much as a week prior to the onset of symptoms, subsequent testing and confirmation using direct testing methods such as respiratory swabs and blood samples.

As illustrated in the following case study, this research is particularly vital for countries like Brazil, in which half the population is estimated to be living without wastewater sanitation services.⁶

The April 13 Technical Notice highlights the non-trivial procedures for establishing a sewage surveillance network, including the use of molecular microbiology techniques, the current strain on resources, and current priorities to test the clinical samples of patients being tested for the virus.

The specific goals of the research are to:

  1. Detect the presence of a viral load in sewage;
  2. Determining its viability by concentrating and extraction viral RNA from sewage samples; and,
  3. Quantify using quantitative Polymerase Chain Reaction techniques.

Unfortunately, the procedures are such that only a few laboratories and research centers in Brazil are currently able to carry out such determinations.

The Bigger Problem – Populations without Sanitation

Of greater concern beyond those operating municipal wastewater treatment facilities is the world’s underserved populations living without adequate sanitation. Brazil serves as a poignant case study in this respect. Their perilous situation is likely why this issue has garnered greater visibility, earlier among practitioners in Brazil compared to what I have observed in North America.

Historically, Brazilian sanitation has been relatively undeveloped as compared to other emerging Countries.⁷ In 2018, the percentage of the Brazilian population with water and sewage service was 83.6% and 53.2%, respectively; however, only 46.3% of the sewage volume is effectively treated.⁸

Worldwide, Brazil ranks 112th out of 200 Countries in this respect and thus its situation has had a negative effect on health indicators. For example, in 2017, the number of hospitalizations due to waterborne diseases was 12.46 per 10,000 inhabitants.⁹ Moreover, Brazil has 13.6 million people living in slums, according to the Data Favela Research Institute.¹⁰ Most of these communities source water from, and discharge sewage directly into streams and rivers.

As noted in the Technical Notice published by Brazilian authorities on March 30, this situation highlights another important implication of potential fecal-oral transmission of Sars-CoV-2 that is directly related to the health situation in Brazil. Specifically, because only 46% of the country's sewage is treated, during the pandemic huge viral loads are likely pouring into the country’s streams and the rivers.

Thus, populations without adequate sanitation may face increased risk of transmission from environmental contamination and direct exposure to untreated waste. According to the Data Favela Research Institute, 70% of families living in Brazil’s slums have already experienced a drop in income due to the coronavirus outbreak. Furthermore, these populations are unlikely to have access to adequate health care and are likely to be far more vulnerable to the disease than surrounding populations.

While the vulnerability of these populations to disease has been so for some time, an emerging consequence of the status quo in the current context of the global Covid-19 pandemic may provide the tipping point needed for action. The nature of the disease – a pre-symptomatic contagious period with a proportion of the infected population functioning as asymptomatic carriers – in combination with much of Brazil’s underserved population living in favelas that are both geographically and economically integrated into the larger, urban population, yields additional concerns. Specifically:

Populations with inadequate wastewater treatment may serve as a refuge for the virus, potentially sustaining the pandemic.

Thus, the latest Brazilian Notice calls for “urgent, coordinated actions by professionals in the areas of health, sanitation, academia and government”, noting that the social inequality and extreme deficit of sanitation services in Brazil will likely aggravate the current scenario of the public health emergency.¹¹

To put this issue into perspective, approximately 100 million Brazilians do not have access to sewage collection services and 35 million do not have access to treated water.¹² See figure 1.

Figure 1. Sewage Coverage as a Percent of Population¹³

Acknowledgements

Special thanks to Dr. Paula A.D. Vilela, PhD from the University of São Paulo (USP) for directing me to various technical notices and information sources contained herein, including many discussions about the current situation in Brazil and the deliberations among her peers on the subject. Dr. Vilela is a professional engineer and respected authority in the subjects of Wastewater, Water Reuse and Project Management in Latin America, working with multinational industrial clients and Municipalities.

Sources

¹ US Environmental Protection Agency: An emerging contaminant is a chemical or material characterized by a perceived, potential, or real threat to human health or the environment or by a lack of published health standards. [Emphasis added.]

² US Geological Survey: Any synthetic or naturally occurring chemical or any microorganism that is not commonly monitored in the environment but has the potential to enter the environment and cause known or suspected adverse ecological and (or) human effects. [Emphasis added.]

³ English Translation of Portuguese Technical Notice.

⁴ English Translation of Portuguese Technical Notice, March 30, 2020.

⁵ Wu Fuqing et. al. 2020, SARS-CoV-2 titers in wastewater are higher than expected from clinically confirmed cases; MedRxiv, Reprint Server for Health Sciences.

⁶ National Sanitation Information System Water and Sewage Services Diagnostic Report – 2016.

⁷ 2016, National Sanitation Information System, Water and Sewage Services Diagnostic Report.

⁸ 2018, National Sanitation Information System, Water and Sewage Services Diagnostic Report.

⁹ Ibid.

¹⁰ Favella: A shantytown in or near a city, especially in Brazil; a slum area.

¹¹ English translation of Portuguese Technical Notice, March 30th, 2020.

¹² 2018, National Sanitation Information System.

¹³ “Industry Scenario.” Aegea.

About the Author

Tyler Elm, BSc. MRM, MBA

Tyler is a strategic advisor to start-ups and seasoned management teams, working with them to develop, implement and scale sustainably-driven innovation strategies, new businesses and functions that engage the internal and external stakeholders of brands and value chains.

Tyler has led the development, implementation and scaling of innovation strategies for the American Automobile Association, the Sustainable Forestry Initiative, Canadian Tire Corporation Ltd., Walmart Stores Inc. and Office Depot Inc., creating entirely new subsidiaries or functions that provide new sources of sustainable value.

Summary

‣ Human waste from people with Covid-19 contains the virus SARS-CoV-2 that causes the disease.

‣ Data support the notion that the SARS-CoV-2 virus may be viable in the environment for prolonged periods under some conditions, facilitating fecal–oral transmission from direct exposure to untreated waste and environmental contamination.

‣ During the Pandemic, Huge Viral Loads are Present in Municipal Wastewater of an infected Population.

‣ Review Occupational Safety Measures – Municipal wastewater facilities are advised to:

  • Review occupational safety measures in light of this new information and uncertainty, adjusting measures accordingly;
  • Ensure staff have adequate personal protective equipment (PPE); and,
  • Promote awareness among facility operators and the use of PPE to avoid inadvertent contact with sewage, including the inhalation of very fine particles suspended in the air.

An Opportunity to Contribute

  • With better information, WWT facilities may function as an early warning system, monitoring the presence and abundance of the virus within a community, including asymptomatic carriers.

Research Gaps

  • Research to determine the potential for fecal–oral transmission of SARS-CoV-2 and the viability of the virus in various environmental conditions.
  • Research to quantify the presence SARS-CoV-2 in sewage and calibrate surveillance data, enhancing its utility as a tool in the fight against this latest coronavirus and its circulation.
  • Research to determine the efficacy of conventional WWT systems in removing SARS-CoV-2 from sewage as well as comparative studies on alternative treatments that may be more effective at a lower cost.

The Bigger Problem

  • Populations without adequate sanitation may face increased risk of transmission.
  • Populations without treated water and wastewater services may serve as a refuge for the virus, potentially sustaining the pandemic.