This study evaluates the synergistic effects of UV coupled with secondary
disinfectants using a model distribution system. In particular, the research employs eight
annular reactors (ARs), which have been widely used in the water industry for evaluating
biofilm growth under conditions representative of drinking water distribution systems.
The chemical disinfectants that are being evaluated for residual disinfection are chlorine
dioxide, monochloramine, and free chlorine. Results indicate that there are synergistic
effects between UV and the chemical disinfectants for controlling microbiological
regrowth in drinking water distribution systems. In particular, in the reactors containing
UV treated water both chlorine dioxide (ClO2) and free chlorine (Cl2) performed better at
reducing the suspended heterotrophic bacteria. When operated with either a low or high
disinfection residual the ClO2 reactor (UV treated) resulted in a greater than 2-log
reduction in heterotrophic plate counts (HPCs) over the reactor that was not treated with
UV light. The Cl2 reactor (UV treated) resulted in approximately 2-log reduction of
HPCs over the reactor that was not treated with UV light. In terms of biofilm reduction,
UV disinfection resulted in a reduction of approximately 0.5-log difference for the ClO2
and NH2Cl ARs. No measurable difference of UV disinfection was detected for the
AR receiving free chlorine. ARs receiving no chemical disinfection resulted in similar
biofilm and suspended HPC levels regardless of whether UV disinfection was present or
not. Overall, these findings indicate that UV prior to chemical disinfection enhances
microbial control in distribution systems. Practically, these results would indicate that a
dual-barrier disinfection system should be considered for pathogen protection at the plant
and distribution system.
Includes 10 references, tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 250 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 8 |
| Published : | 11/01/2002 |
