Inactivation of animal viruses during sewage sludge treatment

Abstract

Using a previously developed filter adsorption technique, the inactivation of a human rotavirus, a coxsackievirus B5, and a bovine parvovirus was monitored during sludge treatment processes. During conventional anaerobic mesophilic digestion at 35 to 36°C, only minor inactivation of all three viruses occurred. The k' values measured were 0.314 log10 unit/day for rotavirus, 0.475 lglo unit/day for coxsackievirus B5, and 0.944 log10 unit/day for parvovirus. However, anaerobic thermophilic digestion at 54 to 56°C led to rapid inactivation of rotavirus (k' > 8.5 log10 units/h) and of coxsackievirus B5 (k' > 0.93 loglo unit/min). Similarly, aerobic thermophilic fermentation at 60 to 61°C rapidly inactivated rotavirus (k' = 0.75 loglo unit/min) and coxsackievirus B5 (k' > 1.67 log1o units/min). Infectivity of parvovirus, however, was only reduced by 0.213 loglo unit/h during anaerobic thermophilic digestion and by 0.353 lglo unit/h during aerobic thermophilic fermentation. Furthermore, pasteurization at 70°C for 30 min inactivated the parvovirus by 0.72 log10 unit/30 min. In all experiments the contribution of temperature to the total inactivation was determined separately and was found to be predominant at process temperatures above 54°C. In conclusion, the most favorable treatment to render sludge hygienically safe from the virological point of view would be a thermal treatment (60°C) to inactivate thermolabile viruses, followed by an anaerobic mesophilic digestion to eliminate thermostable viruses that are more sensitive to chemical and microbial inactivations.

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

“…While our data as well as those of other studies (34,79) thus showed a reduction in the heterogeneity among viruses under extreme conditions, other works have demonstrated that some heterogeneity in virus inactivation kinetics is conserved even under high-pH and -temperature conditions (29,57,63,80,81). Very resistant viruses include phage (82) and ⌽X174 (this study) for high pH and parvovirus and Salmonella phage 28B for high temperature (30,(83)(84)(85)(86). The reasons for these resistant behaviors remain unknown.…”

Occurrence and levels of phages proposed as surrogate indicators of enteric viruses in different types of sludges

“…Although more experimentation is needed, it seems that bacteriophages may be potential model organisms for determining the fate of human viruses in different kinds of sludges, as in the different types of sludges studied, they seem to behave like viruses. Bacteriophages inactivate differently according to the various treatment conditions, as has been described for human viruses (Kock and Strauch 1981;Spillman et al 1987;Straub et al 1994). Therefore, the use of more resistant phages is likely to be recommended.…”

In situ inactivation of animal viruses and a coliphage in nonaerated liquid and semiliquid animal wastes

“…The microbiological requirements can be achieved by various means, notably by pasteurization of the raw sewage sludge followed by mesophilic anaerobic fermentation. Besides inactivating bacteria and parasitic ova, these processes were shown to inactivate enteric viruses of concern for humans (28,31).…”

“…In the present study, we adopted a previously described filter sandwich technique (28,31) to determine the in situ inactivation kinetics of several viruses in various animal excreta that were stored under nonaerated conditions. The results show that, at ambient temperature, some viruses withstand inactivation for extended periods.…”