Coronaviruses in wastewater processes: Source, fate and potential risks

Graphical abstract A graphical representation of the source and fate of Coronavirus in wastewater, showing the potential viral load in feces and urine and their survival removal by during wastewater/sludge treatment. The potential exposure points are represented by the letter ‘E’ in a red background. These exposure points include; the home setting due to faulty plumbing, general public exposure to untreated sewage due to inadequate sanitation and burst sewer pipes. Exposure for WWTW workers from aerosols and direct contact due to sludge collection and treatment. The final exposure scenario is for the general public due to the potential presence of infectious viral particles in treated sewage. Highlights • Viral particle shedding in feces and urine has been reported in people infected with Coronaviruses. • The viral particles in wastewater and may remain infectious for up to 2 days at 20 °C. • Exposure to untreated wastewater within 2 days of viral shedding may potentially cause infections. • Conventional wastewater treatment processes can remove or inactivate these virus particles in wastewater. The last 17 years have seen three major outbreaks caused by coronaviruses, with the latest outbreak, COVID-19, declared a pandemic by the World Health Organization. The frequency of these outbreaks, their mortality and associated disruption to normal life calls for concerted efforts to understand their occurrence and fate in different environments. There is an increased interest in the occurrence of coronaviruses in wastewater from the perspective of wastewater-based epidemiology. However, there is no comprehensive review of the knowledge on coronavirus occurrence, fate and potential transmission in wastewater. This paper, provides a review of the literature on the occurrence of coronaviruses in wastewater treatment processes. We discuss the presence of viral RNA in feces as a result of diarrhoea caused by gastrointestinal infections. We also reviewed the literature on the presence, survival and potential removal of coronaviruses in common wastewater treatment processes. The detection of infectious viral particles in feces of patients raises questions on the potential risks of infection for people exposed to untreated sewage/wastewater. We, therefore, highlighted the potential risk of infection with coronaviruses for workers in wastewater treatment plants and the public that may be exposed through faulty plumbing or burst sewer networks. The mortalities and morbidities associated with the current COVID-19 pandemic warrants a much more focused research on the role of environments, such as wastewater and surface water, in disease transmission. The current wealth of knowledge on coronaviruses in wastewater based on the reviewed literature is scant and therefore calls for further studies.