Ammonia as an In Situ Sanitizer: Influence of Virus Genome Type on Inactivation

Abstract

Treatment. DNA and dsRNA viruses were considerably more resistant than ssRNA viruses, resulting in up to 1,000-fold-longer treatment times to reach a 4-log inactivation. The apparently slower inactivation of DNA viruses was rationalized by the higher stability of DNA than that of ssRNA in HEAM. Pushing the system toward harsher pH (>9) and temperature (>35°C) conditions, such as those encountered in thermophilic digestion and alkaline treatments, led to more consistent inactivation kinetics among ssRNA and other viruses. This suggests that the dependence of inactivation on genome type disappeared in favor of protein-mediated inactivation mechanisms common to all viruses. Finally, we recommend the use of MS2 as a conservative indicator to assess the inactivation of ssRNA viruses and the stable ⌽X174 or dsDNA phages as indicators for persistent viruses. IMPORTANCEViruses are among the most environmentally persistent pathogens. They can be present in high concentrations in human excreta and animal manure (HEAM). Therefore, appropriate treatment of HEAM is important prior to its reuse or discharge into the environment. Here, we investigated the factors that determine the persistence of viruses in HEAM, and we determined the main mechanisms that lead to their inactivation. Unlike other organisms, viruses can have four different genome types (double-or single-stranded RNA or DNA), and the viruses studied herein represent all four types. Genome type appeared to be the major determinant for persistence. Single-stranded RNA viruses are the most labile, because this genome type is susceptible to degradation in HEAM. In contrast, the other genome types are more stable; therefore, inactivation is slower and mainly driven by the degradation of viral proteins. Overall, this study allows us to better understand the behavior of viruses in HEAM.

Virus inactivation in stored human urine, sludge and animal manure under typical conditions of storage or mesophilic anaerobic digestion

“…Inactivation kinetics were assessed in a subset of stored urine, sludge and manure samples at 35°C, and were compared to those obtained in laboratory solution with and without NH 3 . 15,16 As expected, the ssRNA virus MS2 was inactivated more readily than the DNA viruses in most matrices, ( Fig. 1 and ESI † Table S2).…”

“…This ability of the model to accurately predict MS2 inactivation supports the notion that the dominant underlying mechanism of inactivation is basecatalyzed transesterification of the ssRNA genome. 15,16 This appears to be the case in both synthetic solutions and in real matrices such as stored urine, and sludge and manure. Consistent with our results, Gao et al 31 recently reported that during mesophilic anaerobic treatment of Coxsackievirus, the viral genome was the main inactivating target.…”

“…56 Overall, the influence of solids content on the inactivation of different virus types remains poorly understood and needs to be further elucidated. In particular, more research is needed on matrices 16 except for HAdV at pH 9.0 (phosphate buffer [pH 9.0, 50 mmol L −1 carbonate, 40 mmol L −1 phosphate]). The exact rate constants for U4, U12, S2 and M4 are listed in Table S2.…”

“…More extreme conditions of pH or temperature, such as those encountered in thermophilic digestion or alkaline treatment, were required to achieve appreciable inactivation rates. 16 Compared to laboratory solutions, real HEAM matrices exhibit a higher level of complexity: they contain particles, additional chemical constituents (e.g., metals or organic acids), as well as live communities of microorganisms that may contribute to virus inactivation. The current study extends our understanding of virus inactivation from laboratory solutions to real matrices associated with on-site HEAM storage (sludge, stored human urine, animal manure).…”

Struvite Recovery From Source-Separated Urine Utilizing Fluidized Bed Technology

“…Doublestranded RNA and both single-and double-stranded DNA have a higher resistance to inactivation from exposure to high concentrations of ammonia with respect to single-stranded RNA, most likely because of higher stability with respect to its genomes (Decrey et al 2016, Decrey et al 2015.…”