Amsterdam Water Supply uses ozonation as a barrier for bacteria, Giardia and viruses
at two of its water treatment plants: Leiduin and Weesperkarspel. In addition to being used for disinfection,
ozone is also used to eliminate organic micro-pollutants and to stimulate biological activity on
the activated carbon filters following the ozone process. More stringent legislation and
the allowance to put cattle to pasture in the dune infiltration area lead to an increase of
the required disinfection capacity. To improve the disinfection capacity, increasing the
ozone dose is considered (Hijnen et al, 2001). However, higher ozone doses also will lead
to higher bromate concentrations (Orlandini et al, 1997). Further optimization of the
ozone systems is therefore required.
In general, an ozone system can be divided into two parts, the dosing equipment and the
reactive flow part, where the reaction with the dissolved ozone residual takes place.
Ozone can be added to the water stream by bubble columns, or injection devices. The full
scale installations in the Netherlands all apply bubble columns for ozone addition. The hydraulic characteristics of the ozone system influence both parts; mass
transfer and mixing in the bubble column as well as residence time distribution in the
reactive flow part largely determine the disinfection performance and the byproducts
formation. In the bubble column, mixing is required to get a uniform ozone residual
concentration. On the other hand plug flow is desired to get better disinfection results
(prevent short residence times by short-circuiting). However, plug flow lacks mixing
capabilities.
Application of Computational Fluid Dynamics (CFD) offers the possibility of accurately
describing the hydraulic conditions. CFD results are compared to experimental data from
pilot and bench scale experiments. Also full scale experiments were done to determine
the residence time distribution of the ozone system at the Leiduin water treatment plant of
Amsterdam Water Supply. The pilot plant experiments were conducted at the Berenplaat
water treatment plant of the Evides water company. Lab-scale data were collected in a
plug-flow reactor at Kiwa Water Research. Includes 10 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 230 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 7 |
| Published : | 11/01/2005 |
