Research Needs for Wastewater Handling in Virus Outbreak Response

This paper is the fourth and final scientific opinion piece, published as a non-peer reviewed contribution to the Environmental Science and Technology virtual issue on the fate and behaviour of enveloped viruses in the environment.

The authors are Kyle Bibby (University of Pittsburgh, USA), Nathalia Aquino de Carvalho (University of Pittsburgh, USA), and Krista Wigginton (University of Michigan, USA). Together, they provide an expert viewpoint on the current research needs for wastewater handling in virus outbreak response.

Bibby has published extensively on issues relating particularly to Ebola virus in hospital and municipal wastewater. de Carvalho is a PhD candidate working with Bibby and has been a co-author on a number of papers addressing enveloped viruses in wastewater. Wigginton has developed a research focus on understanding the presence and significance on enveloped viruses in the urban water cycle and this focus has particularly included the coronaviruses SARS-CoV and MERS-CoV, both closely related to SARS-CoV-2 (She was the lead author of this prescient paper on the source and fate of pandemic viruses in the urban water cycle in 2015).

This scientific opinion piece was originally published in 2017, thus it does not directly address the COVID-19 outbreak, or the SARS-CoV-2 virus responsible for it. Instead, it was produced in response to the 2014/15 Ebola epidemic, so the identification of “research needs” should be understood in that context.

During the Ebola epidemic, official health advisories promoted the direct disposal of Ebola-contaminated liquid waste into sewage systems and latrines without disinfection. This recommendation was based partially on the assumption of short survival of the enveloped virus in the environment, expected inactivation and dilution in wastewater systems. However, it subsequently became evident that very little research was available on which to base such important assumptions.

Later studies found that Ebola virus persisted longer than expected in the wastewater environment with an approximate T90 (time for 90% inactivation) of 2 days in sterilised wastewater. The authors of this scientific opinion piece argue that this experience exposed shortcomings in knowledge and regulation about appropriate handling of wastewater contaminated with highly infectious pathogens in both resource-rich and resource-poor outbreak settings.

To summarise research conducted on Ebola virus in wastewater and prepare for future viral outbreaks, these authors organised a U.S. National Science Foundation sponsored workshop in 2016. The goal of the workshop was to synthesise current research findings on the behaviour of Ebola virus and its surrogates in the environment, and to develop recommendations for future outbreak response and research needs. The research needs identified included the following:

  • Move toward a Mechanistic Model of Viral Inactivation. Mechanistic, rather than descriptive, models will enable the more rapid extension of observed inactivation behaviour to emerging pathogens and exposure scenarios.
  • Better Characterisation of Exposure and Transmission Pathways in the Wastewater Environment. Potential exposure pathways for both wastewater workers and the general public to untreated wastewater are poorly characterised.
  • Reconsider Surrogate Evaluation of Emerging Pathogens. It has become apparent that the current limited suite of virus surrogates will be inadequate for fine-scale, mechanistic understanding of viral persistence and inactivation in the wastewater environment.
  • Appropriate Disinfection Approaches for High-Strength Waste. Disinfection of pathogen release at the source would be desirable to limit potential downstream exposure and public concern; but, hyperchlorination of high organic content wastes has been found insufficient to ensure effective pathogen inactivation. Therefore, evaluation of alternative disinfection methods, such as pH adjustment or heat, as well as a more mechanistic understanding of chlorine action in high strength waste, are required.
  • Communication. Forthcoming and accurate risk communication is necessary to build both industry and public trust in infectious waste management. Multiple factors must be addressed, including the public’s ability to understand risk, and regionally and socially appropriate risk communication.

The authors concluded that the emergence of multiple viral pathogen outbreaks in recent years has highlighted the value of continued investigation into viral pathogen fate and inactivation in the water environment, as well as appropriate wastewater handling and disinfection. They argued that continued investment in, and attention to, this research area is necessary to better inform future outbreak responses, both minimising the potential for secondary transmission of high consequence pathogens and public concern.

REFERENCE:

Bibby, K., Aquino de Carvalho, N. and Wigginton, K. (2017) Research Needs for Wastewater Handling in Virus Outbreak Response. Environ. Sci. Technol., 51(5), 2534-2535.

https://doi.org/10.1021/acs.est.6b06492

Published by Stuart Khan

Professor of Civil & Environmental Engineering, University of New South Wales

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