Bacteriophage Disinfection of Engineered Waste Streams BACTERIOPHAGE DISINFECTION OF ENGINEERED WASTE STREAMS

The threat of bacterial contaminants in water distribution systems and in the environment is of unremitting concern for environmental engineers. This problem is compounded by the overuse of antibiotics and the resulting increased prevalence of antibiotic resistant pathogens in engineered waste streams and hospital wastewater effluents. Through defects in sewer systems these pathogens are further transferred into the environment. Thus, there is a need to investigate novel and cost effective technologies that can be used to disinfect bacterial pathogens on-site. Enclosed herein is the investigation of bacteriophages (phages) as a novel disinfection agent for engineered waste streams and the resulting design implications for a continuous stirred-tank reactor (CSTR) and a plug flow reactor (PFR). Bacterial disinfection rates were determined for Escherichia coli K12 under a variety of concentrations over the course of 4 h with the phage Ec2. Disinfection rates ranged from 0.16 + 0.1 to 1.8 + 0.1 h. These rates were found to be dependent on the initial bacterial concentration and initial bacterial concentrations below 7 log CFU/mL were found to significantly inhibit disinfection rates compared to higher concentrations (p < 0.05). Using the highest rate obtained at 1.8 + 0.1 h, an assumed volumetric flow of 500 m/day (0.13 MGD), and assuming a desired 3 log reduction, the minimum required reactor volume for a CSTR was found to be 11,540 + 643 m and for a PFR was 80 + 4 m. Taken together these results suggest that at higher bacterial concentrations phages might be suitable for bacterial disinfection in PFRs. However, further work is needed to characterize a broader range of disinfection rates for a wider variety of phages and host systems.