The control of waterborne pathogenic bacteria in fresh water using a biologically active filter

Abstract

The aim of this study was to investigate the control of three species of bacteria commonly associated with biologically contaminated water, using biofiltration. In this study, a laboratory-scale biofilter system was used to investigate the control of Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa in fresh water. Simulated fresh water was inoculated with the test pathogens at a starting inocula of ~1000 CFU 100 mL−1 to challenge the biofilters. Biofilter systems operating within a recirculation configuration demonstrated significant reduction of E. coli (99%), E. faecalis (99%), and P. aeruginosa (92%) after 24 h. Conversely, all sterile control systems did not show any significant reduction in pathogens. Subsequent analysis of the biofilter media after circulation showed that 0% of E. coli was recovered from the biofilter, whereas 0.06% and 1.26% of E. faecalis and P. aeruginosa were recovered respectively. Further investigation demonstrated the reduction of E. coli and enterococci from an environmentally-derived surface water of 99.8% and 99.4% respectively. In conclusion, this work demonstrates that biofilter systems can be used to significantly reduce waterborne pathogenic bacteria within fresh water. The potential application of low-cost, energy efficient biofilter systems for the management of waterborne bacterial pathogens in water supplies is discussed.