Removal of adenovirus in biosolids treatment

Vesuvanathan, S.1, Chellappan, S.1, Rouch, D.A.1, Smith, S.R.2 and Deighton, M1, 1RMIT University, Australia, 2Imperial College London, UK


We aim to examine microbial safety for using biosolids as fertilizers in temperate climate regions, such as southern Australia. This report is concerned with numbers of enteric viruses that survive biosolids treatment. Among enteric viruses generally present in sludge, adenoviruses act as conservative indicator due to their resistance to inactivation. Hence it is important to determine the die off of adenoviruses in sludge treatment. Porcine adenovirus (PAdV 3) was selected as a suitable indicator for the removal of adenoviruses in biosolids treatment. Preliminary treatment simulations of mesophilic anaerobic digestion (MAD) and pan drying were performed. These involved incubation of MAD sludge spiked with PAdV 3 in assay chambers over two weeks, which gave 0.16 log10 per week removal at 35 °C (mesophilic anaerobic digestion) and 0.083 log10 per week removal at 20 °C (pan drying). Further simulation at 20 °C showed a 3-4 log10 removal of virus over a 21-week period.

Key words:

Biosolids, Adenovirus, drying pan simulation.



Biosolids, treated sewage sludge produced in wastewater treatment, contain organic matter and nutrients. Biosolids are applied in agriculture as fertilizers and soil conditioners. They improve the water holding capacity of the soil. However, their microbial quality has to be assured for safe recycling as fertilizers.  This paper reports on microbial safety of biosolids by estimating the number of infectious viruses that survive the wastewater treatment.

Viruses in biosolids

There are 140 different types of viruses in wastewater that can potentially affect humans by causing respiratory diseases, acute gastroenteritis and hepatitis (Gerba et al., 2002). They adsorb to the surfaces of the sewage sludge (Brewster et al., 2005)


Adenoviruses are non-enveloped, icosahedral viruses with ds DNA. Based on their site of infection, they are categorized into 6 subgroups A-F containing 51 serotypes (Hayashi and Hogg, 2007). Among enteric viruses, adenoviruses are the second most important pathogen causing gastroenteritis in children and they have shown higher prevalence in wastewater than most other enteric viruses (Fong et al., 2010).

Drying pan simulation

In sludge treatment, pan drying and stockpiling are processes commonly used in Australia. We developed a drying pan simulation system to determine the treatment efficiency of pan drying in removing viruses in biosolids. This type of simulation provides a safe environment to perform experiments. This will also help in identifying environmental factors that cause the destruction of infectious viruses in sludge.

Porcine adenovirus as indicator

Porcine adenovirus 3 (PAdV 3) was selected as suitable indicator for the simulation. PAdV 3 shares high level of homology with human adenovirus (Reddy et al., 1998).  Moreover, PAdV 3 has a low risk of infection to humans compared to human adenoviruses (Bangari, 2004).

Detection methods

Traditional cell culture assay fails to propagate some groups of enteric viruses and the methods are laborious, inconsistent and expensive (Fong  et al., 2005). RT PCR is widely prescribed for quantitative detection of adenoviruses in environmental samples, (Mattison and Bidawid et al., 2009). RT PCR used closed system which avoids cross contamination and it is also timely in providing quantitative data (Fong  et al., 2005).

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