To investigate the impact of ultraviolet (UV) disinfection on water distribution system biofilms, two model
distribution systems were operated in parallel: one received a simulated potable water disinfected
with UV light, whereas the control system received the same influent without treatment. In each
of five experiments, the bulk and biofilm populations were monitored until the density of
heterotrophic bacteria reached steady-state, at which time an opportunistic pathogen was added
to the systems to simulate an intrusion event. In addition, the microbial composition of the
biofilm and bulk fluid communities of each system were investigated using intergenic
transcribed spacer (ITS) analysis, a method of DNA fingerprinting. UV disinfection did not
consistently decrease the density of heterotrophic bacteria in the biofilm; densities were
consistently greater in the UV system in 2-hour HRT experiments, but greater in the control
system in 12-hour HRT experiments. The DNA fingerprints from the UV system varied greatly
among the experiments. The variety of strains surviving UV irradiation to form a part of the
biofilm in the UV system, despite the high UV dose applied, may be due to particle shielding of
susceptible strains of bacteria. Collimated beam tests of isolates from the UV system confirmed
that bacteria that were susceptible to UV irradiation in planktonic form were present in the
biofilm of the UV system.
Includes 2 references.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 220 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 3 |
| Published : | 11/01/2002 |
