The responses of Escherichia coli, Vibrio cholerae, Aeromonas hydrophila and Pseudomonas aeruginosa to pulsed Ultra-volet light inactivation

Abstract

The effect of pulse ultra violet (PUV) light on 107cfu/mL and 103cfu/mL concentrations of Escherichia coli, Vibrio cholerae, Aeromonas hydrophila and Pseudomonas aeruginosa were investigated. Further experiments investigated how the efficiency of PUV may be affected by water depth. For 107cfu/mL, E. coli, A. hydrophila, P. aeruginosa and V. cholerae were inactivated completely after 10, 20, 40 and 80 pulses respectively. Treatment of E. coli, A. hydrophila, P. aeruginosa and V. cholerae with 5 pulses however resulted in 100% inactivation for E. coli and 99.99% for the other bacteria. For 103cfu/mL, 3 pulses of UV light treatment were required to inactivate completely all four bacteria. Efficacy of PUV disinfection decreased with increased depth of water. E. coli was more susceptible to PUV light treatment than V. cholerae. The use of E. coli as indicator of potability after disinfection with PUV light may not be appropriate