Inactivation of hepatitis A HM-175/18f, reovirus T1 Lang and MS2 during alkaline stabilization of human biosolids

To compare the inactivation rates of male-specific bacteriophage-2 (MS2), hepatitis A HM-175/18f (HM-175) and reovirus T1 Lang (T1 L) during alkaline stabilization of wastewater residues.

A bench scale alkaline stabilization model was used to evaluate the inactivation of MS2 seeded into raw sludge simultaneously with HM-175 or T1 L. Stabilization was performed in triplicate at 28 and 4 degrees C for both viral combinations. During stabilization at 28 and 4 degrees C, MS2 and T1 L concentrations were similar at each time point (t = 0.1, 2, 12 and 24 h). MS2 and HM-175 concentrations were also similar at each time point during stabilization at 28 degrees C. At 4 degrees C, MS2 and HM-175 concentrations were not similar at the first two time points (t = 0.1 and 2 h), but were similar at later time points (t = 12 and 24 h).

The inactivation rates of T1 L at 4 degrees C and both T1 L and HM-175 at 28 degrees C were similar to the inactivation rate of MS2 at all time points. At 4 degrees C, MS2 was inactivated at a faster rate during the first two time points (t = 0.1 and 2 h) than HM-175, but was inactivated similarly at later time points (t = 12 and 24 h).

Phages, such as MS2, would be ideal indicators for the presence of enteric viruses in wastewater residues because of their ubiquity, nonpathogenic nature, low cost and time associated with their detection. The findings of this study suggest that MS2 could serve as an indicator for monitoring the persistence of enteric viruses, such as HM-175 and T1 L, during alkaline stabilization performed at moderate temperatures (28 degrees C), but may not serve as an indicator for HM-175 at reduced temperature (4 degrees C). The utility of MS2 as an indicator of viral persistence during biosolids treatment should be further evaluated, as the increased efficiency and frequency of pathogen monitoring associated with their use may reduce the potential public health risk associated with biosolids, facilitating a greater acceptance for their land application.