Existing water disinfection processes, such as chlorination, have frequently
failed to comply with the Safe Drinking Water Standards because of the formation of
disinfectant byproducts (DBP). The formation of undesirable DBPs can be prevented by
using ultraviolet light (UV), which can inactivate microorganisms by damaging their
DNA. The major disadvantages of UV disinfection are: UV intensity decreases
sharply with its passage in water and its decrease is even more significant with high water
turbidity; microorganisms attached (hidden) to suspended particles may escape UV
irradiation reducing the UV treatment efficiency; and, microbial DNA, once damaged
by UV, can be repaired via enzyme repair systems (e.g., photlyase and excision repair)
resulting in survival of the microorganisms. In this study, a water disinfection process
using UV in conjunction with ultrasound (US) was investigated. A series of experiments
were carried out to test the following hypotheses: Hypothesis 1 - UV and US interact
synergistically to enhance the disinfection efficiency; Hypothesis 2 - the rates of
disinfection by UV, US, and their combination (UVUS) follow the first order or pseudo-first-
order kinetics. Experiments were performed in a 4-liter batch reactor equipped with
UV and US sources. Water containing Escherichia coli (K-12 strains), as surrogate
bacteria, was run through the reactor. Using the total viable count data and mathematical
model, the inactivation rate constants, kuv, kus, and kuvus for the UV, US, and UVUS
treatments, respectively, were determined. The results suggest that the combined effect of
UV and US are likely synergistic, and that the rate of inactivation by UV, US, and UVUS
can be explained by the first-order kinetics. Includes 12 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.3 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 43 |
| Published : | 06/01/2007 |
