Characterization of virucidal agents in activated sludge

Area of Science:

• Environmental microbiology
• Water treatment
• Virology

Background:

• Mixed-liquor suspended solids (MLSS) in activated sludge exhibit virus inactivation properties.
• Enteric viruses, including poliovirus and rotavirus, lose infectivity in MLSS.

Purpose of the Study:

• To identify the agents responsible for virus inactivation in activated sludge.
• To characterize the properties of these virucidal agents.

Main Methods:

• Testing virus infectivity in MLSS under various conditions (temperature, aeration, solids concentration).
• Fractionation of MLSS to localize virucidal activity.
• Assessing the impact of heat, antibiotics, and microbial seeding on activity.

Main Results:

• MLSS irreversibly inactivates enteric viruses.
• Virucidal activity is temperature-dependent but significant at 4°C.
• Activity is primarily associated with the particulate fraction and microorganisms.
• Autoclaved effluent seeded with MLSS can produce virucidal activity.

Conclusions:

• Microorganisms within MLSS are responsible for the observed virucidal activity.
• The virucidal components are likely microbial and may be short-lived or cell-bound.