**2.3 Survival of coronavirus in water and wastewater effluents**

The onset of respiratory infections on a large scale in the human population informs the need for detailed information concerning the survival of coronavirus in water and wastewater effluents. The persistence of several coronaviruses, such as feline infectious peritonitis virus (FIPV) and human coronavirus 229E (HCoV-229E), has been analyzed in tap water and wastewater samples [37]. Filtered tap water showed a lesser number of viruses [37]. Moreover, the study also revealed that coronavirus persistence in wastewater depended on temperature and levels of organic matter. To inactivate the coronaviruses in tap water at the level of 99.9% at 23°C, 10 days were required. Further study revealed that these viruses may survive up to 588 days in tap water at 4°C [37]. However, the time required to inactivate the coronaviruses in wastewater plant effluents up to 99.9% varied between 2.3 to 3.5 days at 23°C [37]. This study also revealed that the transmission risk of coronavirus through water is less in comparison to enteroviruses, such as poliovirus 1, due to the faster inactivation of coronaviruses in wastewater effluents at ambient temperature.

However, with the current inactivation and persistence estimates on surrogate viruses, it is difficult to predict the fate of SARS-CoV-2 in water and wastewater. Several researchers have initiated study of SARS-CoV-2 persistence in water and wastewater. In one of the studies, 90% reduction (T90) in infectious SARS-CoV-2 in tap water and wastewater at room temperature was observed after 1.5 and 1.7 days, respectively [38]. However, in wastewater the T90 values for infectious SARS-CoV-2 were reported as 15 min and 2 min at 50°C and 70°C, respectively [38]. Researchers have identified SARS-CoV-2 RNA in river water. However, no infectivity detected in cultured cells was observed for the recovered SARS-CoV-2 [39]. As mentioned before, this emphasizes that the identification of viral RNA in the environment does not equate to presence of infectious virus. In another study, it was revealed that SARS-CoV-2 may survive up to 14 days under laboratory conditions at 4°C in a virus transport medium. SARS-CoV-2 was incubated in a virus transport medium at a final concentration ~ 6·8 log10 TCID50 per mL at 4°C. After 14 days, there was only a 0·7 log10 reduction in infectious titer observed [9].

#### **2.4 SARS-CoV-2 persistence in hospital and industrial wastewater**

Apart from enteric viruses, certain species of coronaviruses may also remain present in wastewater [40]. However, the persistence of SARS-CoV-2 in wastewater and the potential for transmission through the fecal-oral route has yet to be confirmed. The studies have confirmed the inhibiting effect of wastewater on the persistence of coronaviruses [41]. In contrast to this, in one of the studies it was also demonstrated that coronavirus surrogates may survive for a longer duration in non-filtered primary effluents in comparison to filtered samples [37]. The longer

#### *Environmental Persistence of SARS-CoV-2 and Disinfection of Work Surfaces in View… DOI: http://dx.doi.org/10.5772/intechopen.104520*

survival duration in non-filtered water is primarily attributed to the presence of organic sediments which may provide protection from chemical or biological inactivating agents present in water. In contrast, the available data on surrogate viruses for SARS-COV-2 suggest that the novel coronavirus may be less persistent in wastewater, primarily due to the presence of organic substances as well as inhibiting matrix autochthonous flora, including protozoa, which may contribute proteases and nucleases resulting in faster inactivation of the virus [42].

As a response to the SARS-CoV-2 pandemic and relatively high transmissibility of SARS-CoV-2, several countries have implemented the monitoring of wastewater streams to confirm the presence of the virus in the community, with special reference to asymptomatic individuals and the possibility of risk to contamination of wastewater and risk to solid waste treatment plant employees [43].

SARS-CoV-2 RNA has been detected in human feces [44] and in raw sewage and sludge [45, 46]. The levels correlate with the COVID-19 epidemiological curve and increased number of hospital admissions [46]. Again, the detection of viral RNA does not necessarily indicate the presence of infectious virus particles; rather it indicates the viral prevalence in community.

SARS-CoV-2 RNA was also detected in the wastewater at the Amsterdam Schiphol Airport (Netherlands) and the wastewater treatment plant in Kaatsheuvel (Netherlands) in 2020. This was a crucial finding, since the first case of COVID-19 was reported in February 2020 and viral genetic materials in wastewater samples were detected in March 2020 in Netherland [47]. In one of the studies, SARS-CoV was found to remain infectious at 20°C in wastewater for up to 2 days and viral genomic RNA was isolated for about 8 days [48]. It is not unexpected that SARS-CoV RNA can be detected in wastewater following disinfection protocols using chlorine [48].

Most of these reports are discussing the detection of viral RNA in hospital and sewage water, which does not necessarily confirm the presence of infectious virus. The real challenge is to identify and prevent the transmission of infectious SARS-CoV-2 particles in bioaerosols created during flushing of toilets. Several studies have reported the presence of high concentrations of SARS-CoV-2 in aerosols from patients' toilets and the neighboring environment in hospitals [11, 49, 50]. Thus, toilets may represent one of the most highly contaminated areas of the hospital and may play a potential role in COVID-19 transmission in hospitals. The above studies justify the requirement for adequate disinfection protocols in hospital premises when treating COVID-19 patients, with the aim of inactivating the virus and mitigating possible subsequent spread in hospital wastewater.

## **2.5 Viral persistence in sewage and biological solids**

The possibility of transmission of SARS-CoV-2 from asymptomatic patients via the fecal-oral route is under study. Wastewater-based viral epidemiology and surveillance of sewage material may provide valuable information regarding the prevalence of SARS-CoV-2 in the human population, which may be used as an early warning system in disease forecasting. In biological waste materials and specimens, such as in human serum, plasma, feces, and sputum, SARS-CoV may survive up to 96 hours. However, in human urine, the virus survives for a lesser time, probably due to the presence of urea and adverse pH conditions [51]. Although in one of the experiments SARS-CoV-2 was cultured from feces of confirmed positive patients in the laboratory, still no cases of SARS-CoV-2 infections have been attributed to sewage transmission [52]. The stringency of biological waste treatment also contributes to inactivation of the virus, limiting the amount of infectious virus remaining in these waste streams [53].

Other biological waste materials, such as personal protective equipment (PPE) including masks, gloves, etc., may play roles in the individual-to-individual transmission of SARS-CoV-2. These biowaste materials should be properly segregated according to waste type, and should be subjected to disinfection modalities to minimize the risk of the spread of infection in the environment [54]. For recycling of PPE (gowns, medical gloves, masks and other face and eye shields) waste into value-added products, several advanced processes, such as aminolysis, glycolysis, pyrolysis, hydrogenation, hydrolysis, and gasification are now in practice at the industrial level [55].

Currently, there are only few robust studies that have been reported on reuse of PPE. Thus, the reuse of PPE may harm the healthcare worker via accidental contamination. Therefore, to avoid the possibility of accidental infection, the direct reuse of PPE (i.e., rendering contaminated PPE non-infectious) is not advisable even during acute shortages of PPE [56].
