Phage Therapy for Sludge Bulking Using a Novel Bacteriophage Infecting Filamentous Bacterium, Sphaerotilus Natans

Over the past three decades, it has become apparent that bacteriophages are ubiquitous, abundant and ecologically important in the environment. Phages have been used in medical applications and meat industry where the primary objective has been to kill pathogenic bacteria using lytic phages. Biomass bulking due to the overgrowth of filamentous bacteria in activated sludge bioreactors is a common worldwide problem. Considering that phages are abundant in wastewater treatment plants, surprisingly little is known about their biological control of sludge bulking using bacteriophages infecting filamentous bacteria. This research demonstrated the application of lytic bacteriophage-mediated biocontrol of sludge bulking in the activated sludge process using Sphaerotilus Natans as the filamentous organism. Based on the morphology bacteriophages belong to the family Myoviridae with a hexagonal head, a contractile tail, helical symmetry, a collar and filaments. Phage to host ratio for optical infection was founded to be 1:1000 with 61 % host death. The application of phage did not affect nutrient removal efficiency, suggesting no collateral damage. Bacteriophage-mediated biocontrol promises a great potential for large-scale application as economic agent in the control of filamentous overgrowth and foaming.